text: /*
   * Copyright 2010-present Facebook, Inc.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *   http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include <folly/io/async/test/AsyncSocketTest2.h>
  
  #include <folly/ConstexprMath.h>
  #include <folly/ExceptionWrapper.h>
  #include <folly/Random.h>
  #include <folly/SocketAddress.h>
  #include <folly/io/async/AsyncSocket.h>
  #include <folly/io/async/AsyncTimeout.h>
  #include <folly/io/async/EventBase.h>
  
  #include <folly/experimental/TestUtil.h>
  #include <folly/io/IOBuf.h>
  #include <folly/io/async/test/AsyncSocketTest.h>
  #include <folly/io/async/test/Util.h>
  #include <folly/portability/GMock.h>
  #include <folly/portability/GTest.h>
  #include <folly/portability/Sockets.h>
  #include <folly/portability/Unistd.h>
  #include <folly/test/SocketAddressTestHelper.h>
  
  #include <boost/scoped_array.hpp>
  #include <fcntl.h>
  #include <sys/types.h>
  #include <iostream>
  #include <thread>
  
  using namespace boost;
  
  using std::string;
  using std::vector;
  using std::min;
  using std::cerr;
  using std::endl;
  using std::unique_ptr;
  using std::chrono::milliseconds;
  using boost::scoped_array;
  
  using namespace folly;
  using namespace folly::test;
  using namespace testing;
  
  namespace fsp = folly::portability::sockets;
  
  class DelayedWrite: public AsyncTimeout {
   public:
    DelayedWrite(const std::shared_ptr<AsyncSocket>& socket,
        unique_ptr<IOBuf>&& bufs, AsyncTransportWrapper::WriteCallback* wcb,
        bool cork, bool lastWrite = false):
      AsyncTimeout(socket->getEventBase()),
      socket_(socket),
      bufs_(std::move(bufs)),
      wcb_(wcb),
      cork_(cork),
      lastWrite_(lastWrite) {}
  
   private:
    void timeoutExpired() noexcept override {
      WriteFlags flags = cork_ ? WriteFlags::CORK : WriteFlags::NONE;
      socket_->writeChain(wcb_, std::move(bufs_), flags);
      if (lastWrite_) {
        socket_->shutdownWrite();
      }
    }
  
    std::shared_ptr<AsyncSocket> socket_;
    unique_ptr<IOBuf> bufs_;
    AsyncTransportWrapper::WriteCallback* wcb_;
    bool cork_;
    bool lastWrite_;
  };
  
  ///////////////////////////////////////////////////////////////////////////
  // connect() tests
  ///////////////////////////////////////////////////////////////////////////
  
  /**
   * Test connecting to a server
   */
  TEST(AsyncSocketTest, Connect) {
    // Start listening on a local port
    TestServer server;
  
    // Connect using a AsyncSocket
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback cb;
    socket->connect(&cb, server.getAddress(), 30);
  
    evb.loop();
  
    ASSERT_EQ(cb.state, STATE_SUCCEEDED);
    EXPECT_LE(0, socket->getConnectTime().count());
    EXPECT_EQ(socket->getConnectTimeout(), std::chrono::milliseconds(30));
  }
  
  enum class TFOState {
    DISABLED,
    ENABLED,
  };
  
  class AsyncSocketConnectTest : public ::testing::TestWithParam<TFOState> {};
  
  std::vector<TFOState> getTestingValues() {
    std::vector<TFOState> vals;
    vals.emplace_back(TFOState::DISABLED);
  
  #if FOLLY_ALLOW_TFO
    vals.emplace_back(TFOState::ENABLED);
  #endif
    return vals;
  }
  
  INSTANTIATE_TEST_CASE_P(
      ConnectTests,
      AsyncSocketConnectTest,
      ::testing::ValuesIn(getTestingValues()));
  
  /**
   * Test connecting to a server that isn't listening
   */
  TEST(AsyncSocketTest, ConnectRefused) {
    EventBase evb;
  
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
  
    // Hopefully nothing is actually listening on this address
    folly::SocketAddress addr("127.0.0.1", 65535);
    ConnCallback cb;
    socket->connect(&cb, addr, 30);
  
    evb.loop();
  
    EXPECT_EQ(STATE_FAILED, cb.state);
    EXPECT_EQ(AsyncSocketException::NOT_OPEN, cb.exception.getType());
    EXPECT_LE(0, socket->getConnectTime().count());
    EXPECT_EQ(std::chrono::milliseconds(30), socket->getConnectTimeout());
  }
  
  /**
   * Test connection timeout
   */
  TEST(AsyncSocketTest, ConnectTimeout) {
    EventBase evb;
  
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
  
    // Try connecting to server that won't respond.
    //
    // This depends somewhat on the network where this test is run.
    // Hopefully this IP will be routable but unresponsive.
    // (Alternatively, we could try listening on a local raw socket, but that
    // normally requires root privileges.)
    auto host =
        SocketAddressTestHelper::isIPv6Enabled() ?
        SocketAddressTestHelper::kGooglePublicDnsAAddrIPv6 :
        SocketAddressTestHelper::isIPv4Enabled() ?
        SocketAddressTestHelper::kGooglePublicDnsAAddrIPv4 :
        nullptr;
    SocketAddress addr(host, 65535);
    ConnCallback cb;
    socket->connect(&cb, addr, 1); // also set a ridiculously small timeout
  
    evb.loop();
  
    ASSERT_EQ(cb.state, STATE_FAILED);
    ASSERT_EQ(cb.exception.getType(), AsyncSocketException::TIMED_OUT);
  
    // Verify that we can still get the peer address after a timeout.
    // Use case is if the client was created from a client pool, and we want
    // to log which peer failed.
    folly::SocketAddress peer;
    socket->getPeerAddress(&peer);
    ASSERT_EQ(peer, addr);
    EXPECT_LE(0, socket->getConnectTime().count());
    EXPECT_EQ(socket->getConnectTimeout(), std::chrono::milliseconds(1));
  }
  
  /**
   * Test writing immediately after connecting, without waiting for connect
   * to finish.
   */
  TEST_P(AsyncSocketConnectTest, ConnectAndWrite) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
  
    if (GetParam() == TFOState::ENABLED) {
      socket->enableTFO();
    }
  
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // write()
    char buf[128];
    memset(buf, 'a', sizeof(buf));
    WriteCallback wcb;
    socket->write(&wcb, buf, sizeof(buf));
  
    // Loop.  We don't bother accepting on the server socket yet.
    // The kernel should be able to buffer the write request so it can succeed.
    evb.loop();
  
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  
    // Make sure the server got a connection and received the data
    socket->close();
    server.verifyConnection(buf, sizeof(buf));
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
    EXPECT_EQ(socket->getConnectTimeout(), std::chrono::milliseconds(30));
  }
  
  /**
   * Test connecting using a nullptr connect callback.
   */
  TEST_P(AsyncSocketConnectTest, ConnectNullCallback) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    if (GetParam() == TFOState::ENABLED) {
      socket->enableTFO();
    }
  
    socket->connect(nullptr, server.getAddress(), 30);
  
    // write some data, just so we have some way of verifing
    // that the socket works correctly after connecting
    char buf[128];
    memset(buf, 'a', sizeof(buf));
    WriteCallback wcb;
    socket->write(&wcb, buf, sizeof(buf));
  
    evb.loop();
  
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  
    // Make sure the server got a connection and received the data
    socket->close();
    server.verifyConnection(buf, sizeof(buf));
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test calling both write() and close() immediately after connecting, without
   * waiting for connect to finish.
   *
   * This exercises the STATE_CONNECTING_CLOSING code.
   */
  TEST_P(AsyncSocketConnectTest, ConnectWriteAndClose) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    if (GetParam() == TFOState::ENABLED) {
      socket->enableTFO();
    }
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // write()
    char buf[128];
    memset(buf, 'a', sizeof(buf));
    WriteCallback wcb;
    socket->write(&wcb, buf, sizeof(buf));
  
    // close()
    socket->close();
  
    // Loop.  We don't bother accepting on the server socket yet.
    // The kernel should be able to buffer the write request so it can succeed.
    evb.loop();
  
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  
    // Make sure the server got a connection and received the data
    server.verifyConnection(buf, sizeof(buf));
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test calling close() immediately after connect()
   */
  TEST(AsyncSocketTest, ConnectAndClose) {
    TestServer server;
  
    // Connect using a AsyncSocket
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Hopefully the connect didn't succeed immediately.
    // If it did, we can't exercise the close-while-connecting code path.
    if (ccb.state == STATE_SUCCEEDED) {
      LOG(INFO) << "connect() succeeded immediately; aborting test "
                         "of close-during-connect behavior";
      return;
    }
  
    socket->close();
  
    // Loop, although there shouldn't be anything to do.
    evb.loop();
  
    // Make sure the connection was aborted
    ASSERT_EQ(ccb.state, STATE_FAILED);
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test calling closeNow() immediately after connect()
   *
   * This should be identical to the normal close behavior.
   */
  TEST(AsyncSocketTest, ConnectAndCloseNow) {
    TestServer server;
  
    // Connect using a AsyncSocket
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Hopefully the connect didn't succeed immediately.
    // If it did, we can't exercise the close-while-connecting code path.
    if (ccb.state == STATE_SUCCEEDED) {
      LOG(INFO) << "connect() succeeded immediately; aborting test "
                         "of closeNow()-during-connect behavior";
      return;
    }
  
    socket->closeNow();
  
    // Loop, although there shouldn't be anything to do.
    evb.loop();
  
    // Make sure the connection was aborted
    ASSERT_EQ(ccb.state, STATE_FAILED);
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test calling both write() and closeNow() immediately after connecting,
   * without waiting for connect to finish.
   *
   * This should abort the pending write.
   */
  TEST(AsyncSocketTest, ConnectWriteAndCloseNow) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Hopefully the connect didn't succeed immediately.
    // If it did, we can't exercise the close-while-connecting code path.
    if (ccb.state == STATE_SUCCEEDED) {
      LOG(INFO) << "connect() succeeded immediately; aborting test "
                         "of write-during-connect behavior";
      return;
    }
  
    // write()
    char buf[128];
    memset(buf, 'a', sizeof(buf));
    WriteCallback wcb;
    socket->write(&wcb, buf, sizeof(buf));
  
    // close()
    socket->closeNow();
  
    // Loop, although there shouldn't be anything to do.
    evb.loop();
  
    ASSERT_EQ(ccb.state, STATE_FAILED);
    ASSERT_EQ(wcb.state, STATE_FAILED);
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test installing a read callback immediately, before connect() finishes.
   */
  TEST_P(AsyncSocketConnectTest, ConnectAndRead) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    if (GetParam() == TFOState::ENABLED) {
      socket->enableTFO();
    }
  
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    if (GetParam() == TFOState::ENABLED) {
      // Trigger a connection
      socket->writeChain(nullptr, IOBuf::copyBuffer("hey"));
    }
  
    // Even though we haven't looped yet, we should be able to accept
    // the connection and send data to it.
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
    uint8_t buf[128];
    memset(buf, 'a', sizeof(buf));
    acceptedSocket->write(buf, sizeof(buf));
    acceptedSocket->flush();
    acceptedSocket->close();
  
    // Loop, although there shouldn't be anything to do.
    evb.loop();
  
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
    ASSERT_EQ(rcb.buffers.size(), 1);
    ASSERT_EQ(rcb.buffers[0].length, sizeof(buf));
    ASSERT_EQ(memcmp(rcb.buffers[0].buffer, buf, sizeof(buf)), 0);
  
    ASSERT_FALSE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test installing a read callback and then closing immediately before the
   * connect attempt finishes.
   */
  TEST(AsyncSocketTest, ConnectReadAndClose) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Hopefully the connect didn't succeed immediately.
    // If it did, we can't exercise the close-while-connecting code path.
    if (ccb.state == STATE_SUCCEEDED) {
      LOG(INFO) << "connect() succeeded immediately; aborting test "
                         "of read-during-connect behavior";
      return;
    }
  
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    // close()
    socket->close();
  
    // Loop, although there shouldn't be anything to do.
    evb.loop();
  
    ASSERT_EQ(ccb.state, STATE_FAILED); // we aborted the close attempt
    ASSERT_EQ(rcb.buffers.size(), 0);
    ASSERT_EQ(rcb.state, STATE_SUCCEEDED); // this indicates EOF
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test both writing and installing a read callback immediately,
   * before connect() finishes.
   */
  TEST_P(AsyncSocketConnectTest, ConnectWriteAndRead) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    if (GetParam() == TFOState::ENABLED) {
      socket->enableTFO();
    }
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // write()
    char buf1[128];
    memset(buf1, 'a', sizeof(buf1));
    WriteCallback wcb;
    socket->write(&wcb, buf1, sizeof(buf1));
  
    // set a read callback
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    // Even though we haven't looped yet, we should be able to accept
    // the connection and send data to it.
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
    uint8_t buf2[128];
    memset(buf2, 'b', sizeof(buf2));
    acceptedSocket->write(buf2, sizeof(buf2));
    acceptedSocket->flush();
  
    // shut down the write half of acceptedSocket, so that the AsyncSocket
    // will stop reading and we can break out of the event loop.
    shutdown(acceptedSocket->getSocketFD(), SHUT_WR);
  
    // Loop
    evb.loop();
  
    // Make sure the connect succeeded
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
  
    // Make sure the AsyncSocket read the data written by the accepted socket
    ASSERT_EQ(rcb.state, STATE_SUCCEEDED);
    ASSERT_EQ(rcb.buffers.size(), 1);
    ASSERT_EQ(rcb.buffers[0].length, sizeof(buf2));
    ASSERT_EQ(memcmp(rcb.buffers[0].buffer, buf2, sizeof(buf2)), 0);
  
    // Close the AsyncSocket so we'll see EOF on acceptedSocket
    socket->close();
  
    // Make sure the accepted socket saw the data written by the AsyncSocket
    uint8_t readbuf[sizeof(buf1)];
    acceptedSocket->readAll(readbuf, sizeof(readbuf));
    ASSERT_EQ(memcmp(buf1, readbuf, sizeof(buf1)), 0);
    uint32_t bytesRead = acceptedSocket->read(readbuf, sizeof(readbuf));
    ASSERT_EQ(bytesRead, 0);
  
    ASSERT_FALSE(socket->isClosedBySelf());
    ASSERT_TRUE(socket->isClosedByPeer());
  }
  
  /**
   * Test writing to the socket then shutting down writes before the connect
   * attempt finishes.
   */
  TEST(AsyncSocketTest, ConnectWriteAndShutdownWrite) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Hopefully the connect didn't succeed immediately.
    // If it did, we can't exercise the write-while-connecting code path.
    if (ccb.state == STATE_SUCCEEDED) {
      LOG(INFO) << "connect() succeeded immediately; skipping test";
      return;
    }
  
    // Ask to write some data
    char wbuf[128];
    memset(wbuf, 'a', sizeof(wbuf));
    WriteCallback wcb;
    socket->write(&wcb, wbuf, sizeof(wbuf));
    socket->shutdownWrite();
  
    // Shutdown writes
    socket->shutdownWrite();
  
    // Even though we haven't looped yet, we should be able to accept
    // the connection.
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
  
    // Since the connection is still in progress, there should be no data to
    // read yet.  Verify that the accepted socket is not readable.
    struct pollfd fds[1];
    fds[0].fd = acceptedSocket->getSocketFD();
    fds[0].events = POLLIN;
    fds[0].revents = 0;
    int rc = poll(fds, 1, 0);
    ASSERT_EQ(rc, 0);
  
    // Write data to the accepted socket
    uint8_t acceptedWbuf[192];
    memset(acceptedWbuf, 'b', sizeof(acceptedWbuf));
    acceptedSocket->write(acceptedWbuf, sizeof(acceptedWbuf));
    acceptedSocket->flush();
  
    // Loop
    evb.loop();
  
    // The loop should have completed the connection, written the queued data,
    // and shutdown writes on the socket.
    //
    // Check that the connection was completed successfully and that the write
    // callback succeeded.
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  
    // Check that we can read the data that was written to the socket, and that
    // we see an EOF, since its socket was half-shutdown.
    uint8_t readbuf[sizeof(wbuf)];
    acceptedSocket->readAll(readbuf, sizeof(readbuf));
    ASSERT_EQ(memcmp(wbuf, readbuf, sizeof(wbuf)), 0);
    uint32_t bytesRead = acceptedSocket->read(readbuf, sizeof(readbuf));
    ASSERT_EQ(bytesRead, 0);
  
    // Close the accepted socket.  This will cause it to see EOF
    // and uninstall the read callback when we loop next.
    acceptedSocket->close();
  
    // Install a read callback, then loop again.
    ReadCallback rcb;
    socket->setReadCB(&rcb);
    evb.loop();
  
    // This loop should have read the data and seen the EOF
    ASSERT_EQ(rcb.state, STATE_SUCCEEDED);
    ASSERT_EQ(rcb.buffers.size(), 1);
    ASSERT_EQ(rcb.buffers[0].length, sizeof(acceptedWbuf));
    ASSERT_EQ(memcmp(rcb.buffers[0].buffer,
                             acceptedWbuf, sizeof(acceptedWbuf)), 0);
  
    ASSERT_FALSE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test reading, writing, and shutting down writes before the connect attempt
   * finishes.
   */
  TEST(AsyncSocketTest, ConnectReadWriteAndShutdownWrite) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Hopefully the connect didn't succeed immediately.
    // If it did, we can't exercise the write-while-connecting code path.
    if (ccb.state == STATE_SUCCEEDED) {
      LOG(INFO) << "connect() succeeded immediately; skipping test";
      return;
    }
  
    // Install a read callback
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    // Ask to write some data
    char wbuf[128];
    memset(wbuf, 'a', sizeof(wbuf));
    WriteCallback wcb;
    socket->write(&wcb, wbuf, sizeof(wbuf));
  
    // Shutdown writes
    socket->shutdownWrite();
  
    // Even though we haven't looped yet, we should be able to accept
    // the connection.
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
  
    // Since the connection is still in progress, there should be no data to
    // read yet.  Verify that the accepted socket is not readable.
    struct pollfd fds[1];
    fds[0].fd = acceptedSocket->getSocketFD();
    fds[0].events = POLLIN;
    fds[0].revents = 0;
    int rc = poll(fds, 1, 0);
    ASSERT_EQ(rc, 0);
  
    // Write data to the accepted socket
    uint8_t acceptedWbuf[192];
    memset(acceptedWbuf, 'b', sizeof(acceptedWbuf));
    acceptedSocket->write(acceptedWbuf, sizeof(acceptedWbuf));
    acceptedSocket->flush();
    // Shutdown writes to the accepted socket.  This will cause it to see EOF
    // and uninstall the read callback.
    shutdown(acceptedSocket->getSocketFD(), SHUT_WR);
  
    // Loop
    evb.loop();
  
    // The loop should have completed the connection, written the queued data,
    // shutdown writes on the socket, read the data we wrote to it, and see the
    // EOF.
    //
    // Check that the connection was completed successfully and that the read
    // and write callbacks were invoked as expected.
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
    ASSERT_EQ(rcb.state, STATE_SUCCEEDED);
    ASSERT_EQ(rcb.buffers.size(), 1);
    ASSERT_EQ(rcb.buffers[0].length, sizeof(acceptedWbuf));
    ASSERT_EQ(memcmp(rcb.buffers[0].buffer,
                             acceptedWbuf, sizeof(acceptedWbuf)), 0);
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  
    // Check that we can read the data that was written to the socket, and that
    // we see an EOF, since its socket was half-shutdown.
    uint8_t readbuf[sizeof(wbuf)];
    acceptedSocket->readAll(readbuf, sizeof(readbuf));
    ASSERT_EQ(memcmp(wbuf, readbuf, sizeof(wbuf)), 0);
    uint32_t bytesRead = acceptedSocket->read(readbuf, sizeof(readbuf));
    ASSERT_EQ(bytesRead, 0);
  
    // Fully close both sockets
    acceptedSocket->close();
    socket->close();
  
    ASSERT_FALSE(socket->isClosedBySelf());
    ASSERT_TRUE(socket->isClosedByPeer());
  }
  
  /**
   * Test reading, writing, and calling shutdownWriteNow() before the
   * connect attempt finishes.
   */
  TEST(AsyncSocketTest, ConnectReadWriteAndShutdownWriteNow) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Hopefully the connect didn't succeed immediately.
    // If it did, we can't exercise the write-while-connecting code path.
    if (ccb.state == STATE_SUCCEEDED) {
      LOG(INFO) << "connect() succeeded immediately; skipping test";
      return;
    }
  
    // Install a read callback
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    // Ask to write some data
    char wbuf[128];
    memset(wbuf, 'a', sizeof(wbuf));
    WriteCallback wcb;
    socket->write(&wcb, wbuf, sizeof(wbuf));
  
    // Shutdown writes immediately.
    // This should immediately discard the data that we just tried to write.
    socket->shutdownWriteNow();
  
    // Verify that writeError() was invoked on the write callback.
    ASSERT_EQ(wcb.state, STATE_FAILED);
    ASSERT_EQ(wcb.bytesWritten, 0);
  
    // Even though we haven't looped yet, we should be able to accept
    // the connection.
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
  
    // Since the connection is still in progress, there should be no data to
    // read yet.  Verify that the accepted socket is not readable.
    struct pollfd fds[1];
    fds[0].fd = acceptedSocket->getSocketFD();
    fds[0].events = POLLIN;
    fds[0].revents = 0;
    int rc = poll(fds, 1, 0);
    ASSERT_EQ(rc, 0);
  
    // Write data to the accepted socket
    uint8_t acceptedWbuf[192];
    memset(acceptedWbuf, 'b', sizeof(acceptedWbuf));
    acceptedSocket->write(acceptedWbuf, sizeof(acceptedWbuf));
    acceptedSocket->flush();
    // Shutdown writes to the accepted socket.  This will cause it to see EOF
    // and uninstall the read callback.
    shutdown(acceptedSocket->getSocketFD(), SHUT_WR);
  
    // Loop
    evb.loop();
  
    // The loop should have completed the connection, written the queued data,
    // shutdown writes on the socket, read the data we wrote to it, and see the
    // EOF.
    //
    // Check that the connection was completed successfully and that the read
    // callback was invoked as expected.
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
    ASSERT_EQ(rcb.state, STATE_SUCCEEDED);
    ASSERT_EQ(rcb.buffers.size(), 1);
    ASSERT_EQ(rcb.buffers[0].length, sizeof(acceptedWbuf));
    ASSERT_EQ(memcmp(rcb.buffers[0].buffer,
                             acceptedWbuf, sizeof(acceptedWbuf)), 0);
  
    // Since we used shutdownWriteNow(), it should have discarded all pending
    // write data.  Verify we see an immediate EOF when reading from the accepted
    // socket.
    uint8_t readbuf[sizeof(wbuf)];
    uint32_t bytesRead = acceptedSocket->read(readbuf, sizeof(readbuf));
    ASSERT_EQ(bytesRead, 0);
  
    // Fully close both sockets
    acceptedSocket->close();
    socket->close();
  
    ASSERT_FALSE(socket->isClosedBySelf());
    ASSERT_TRUE(socket->isClosedByPeer());
  }
  
  // Helper function for use in testConnectOptWrite()
  // Temporarily disable the read callback
  void tmpDisableReads(AsyncSocket* socket, ReadCallback* rcb) {
    // Uninstall the read callback
    socket->setReadCB(nullptr);
    // Schedule the read callback to be reinstalled after 1ms
    socket->getEventBase()->runInLoop(
        std::bind(&AsyncSocket::setReadCB, socket, rcb));
  }
  
  /**
   * Test connect+write, then have the connect callback perform another write.
   *
   * This tests interaction of the optimistic writing after connect with
   * additional write attempts that occur in the connect callback.
   */
  void testConnectOptWrite(size_t size1, size_t size2, bool close = false) {
    TestServer server;
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
  
    // connect()
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Hopefully the connect didn't succeed immediately.
    // If it did, we can't exercise the optimistic write code path.
    if (ccb.state == STATE_SUCCEEDED) {
      LOG(INFO) << "connect() succeeded immediately; aborting test "
                         "of optimistic write behavior";
      return;
    }
  
    // Tell the connect callback to perform a write when the connect succeeds
    WriteCallback wcb2;
    scoped_array<char> buf2(new char[size2]);
    memset(buf2.get(), 'b', size2);
    if (size2 > 0) {
      ccb.successCallback = [&] { socket->write(&wcb2, buf2.get(), size2); };
      // Tell the second write callback to close the connection when it is done
      wcb2.successCallback = [&] { socket->closeNow(); };
    }
  
    // Schedule one write() immediately, before the connect finishes
    scoped_array<char> buf1(new char[size1]);
    memset(buf1.get(), 'a', size1);
    WriteCallback wcb1;
    if (size1 > 0) {
      socket->write(&wcb1, buf1.get(), size1);
    }
  
    if (close) {
      // immediately perform a close, before connect() completes
      socket->close();
    }
  
    // Start reading from the other endpoint after 10ms.
    // If we're using large buffers, we have to read so that the writes don't
    // block forever.
    std::shared_ptr<AsyncSocket> acceptedSocket = server.acceptAsync(&evb);
    ReadCallback rcb;
    rcb.dataAvailableCallback = std::bind(tmpDisableReads,
                                          acceptedSocket.get(), &rcb);
    socket->getEventBase()->tryRunAfterDelay(
        std::bind(&AsyncSocket::setReadCB, acceptedSocket.get(), &rcb),
        10);
  
    // Loop.  We don't bother accepting on the server socket yet.
    // The kernel should be able to buffer the write request so it can succeed.
    evb.loop();
  
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
    if (size1 > 0) {
      ASSERT_EQ(wcb1.state, STATE_SUCCEEDED);
    }
    if (size2 > 0) {
      ASSERT_EQ(wcb2.state, STATE_SUCCEEDED);
    }
  
    socket->close();
  
    // Make sure the read callback received all of the data
    size_t bytesRead = 0;
    for (vector<ReadCallback::Buffer>::const_iterator it = rcb.buffers.begin();
         it != rcb.buffers.end();
         ++it) {
      size_t start = bytesRead;
      bytesRead += it->length;
      size_t end = bytesRead;
      if (start < size1) {
        size_t cmpLen = min(size1, end) - start;
        ASSERT_EQ(memcmp(it->buffer, buf1.get() + start, cmpLen), 0);
      }
      if (end > size1 && end <= size1 + size2) {
        size_t itOffset;
        size_t buf2Offset;
        size_t cmpLen;
        if (start >= size1) {
          itOffset = 0;
          buf2Offset = start - size1;
          cmpLen = end - start;
        } else {
          itOffset = size1 - start;
          buf2Offset = 0;
          cmpLen = end - size1;
        }
        ASSERT_EQ(memcmp(it->buffer + itOffset, buf2.get() + buf2Offset,
                                 cmpLen),
                          0);
      }
    }
    ASSERT_EQ(bytesRead, size1 + size2);
  }
  
  TEST(AsyncSocketTest, ConnectCallbackWrite) {
    // Test using small writes that should both succeed immediately
    testConnectOptWrite(100, 200);
  
    // Test using a large buffer in the connect callback, that should block
    const size_t largeSize = 32 * 1024 * 1024;
    testConnectOptWrite(100, largeSize);
  
    // Test using a large initial write
    testConnectOptWrite(largeSize, 100);
  
    // Test using two large buffers
    testConnectOptWrite(largeSize, largeSize);
  
    // Test a small write in the connect callback,
    // but no immediate write before connect completes
    testConnectOptWrite(0, 64);
  
    // Test a large write in the connect callback,
    // but no immediate write before connect completes
    testConnectOptWrite(0, largeSize);
  
    // Test connect, a small write, then immediately call close() before connect
    // completes
    testConnectOptWrite(211, 0, true);
  
    // Test connect, a large immediate write (that will block), then immediately
    // call close() before connect completes
    testConnectOptWrite(largeSize, 0, true);
  }
  
  ///////////////////////////////////////////////////////////////////////////
  // write() related tests
  ///////////////////////////////////////////////////////////////////////////
  
  /**
   * Test writing using a nullptr callback
   */
  TEST(AsyncSocketTest, WriteNullCallback) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket =
      AsyncSocket::newSocket(&evb, server.getAddress(), 30);
    evb.loop(); // loop until the socket is connected
  
    // write() with a nullptr callback
    char buf[128];
    memset(buf, 'a', sizeof(buf));
    socket->write(nullptr, buf, sizeof(buf));
  
    evb.loop(); // loop until the data is sent
  
    // Make sure the server got a connection and received the data
    socket->close();
    server.verifyConnection(buf, sizeof(buf));
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test writing with a send timeout
   */
  TEST(AsyncSocketTest, WriteTimeout) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket =
      AsyncSocket::newSocket(&evb, server.getAddress(), 30);
    evb.loop(); // loop until the socket is connected
  
    // write() a large chunk of data, with no-one on the other end reading.
    // Tricky: the kernel caches the connection metrics for recently-used
    // routes (see tcp_no_metrics_save) so a freshly opened connection can
    // have a send buffer size bigger than wmem_default.  This makes the test
    // flaky on contbuild if writeLength is < wmem_max (20M on our systems).
    size_t writeLength = 32 * 1024 * 1024;
    uint32_t timeout = 200;
    socket->setSendTimeout(timeout);
    scoped_array<char> buf(new char[writeLength]);
    memset(buf.get(), 'a', writeLength);
    WriteCallback wcb;
    socket->write(&wcb, buf.get(), writeLength);
  
    TimePoint start;
    evb.loop();
    TimePoint end;
  
    // Make sure the write attempt timed out as requested
    ASSERT_EQ(wcb.state, STATE_FAILED);
    ASSERT_EQ(wcb.exception.getType(), AsyncSocketException::TIMED_OUT);
  
    // Check that the write timed out within a reasonable period of time.
    // We don't check for exactly the specified timeout, since AsyncSocket only
    // times out when it hasn't made progress for that period of time.
    //
    // On linux, the first write sends a few hundred kb of data, then blocks for
    // writability, and then unblocks again after 40ms and is able to write
    // another smaller of data before blocking permanently.  Therefore it doesn't
    // time out until 40ms + timeout.
    //
    // I haven't fully verified the cause of this, but I believe it probably
    // occurs because the receiving end delays sending an ack for up to 40ms.
    // (This is the default value for TCP_DELACK_MIN.)  Once the sender receives
    // the ack, it can send some more data.  However, after that point the
    // receiver's kernel buffer is full.  This 40ms delay happens even with
    // TCP_NODELAY and TCP_QUICKACK enabled on both endpoints.  However, the
    // kernel may be automatically disabling TCP_QUICKACK after receiving some
    // data.
    //
    // For now, we simply check that the timeout occurred within 160ms of
    // the requested value.
    T_CHECK_TIMEOUT(start, end, milliseconds(timeout), milliseconds(160));
  }
  
  /**
   * Test writing to a socket that the remote endpoint has closed
   */
  TEST(AsyncSocketTest, WritePipeError) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket =
      AsyncSocket::newSocket(&evb, server.getAddress(), 30);
    socket->setSendTimeout(1000);
    evb.loop(); // loop until the socket is connected
  
    // accept and immediately close the socket
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
    acceptedSocket->close();
  
    // write() a large chunk of data
    size_t writeLength = 32 * 1024 * 1024;
    scoped_array<char> buf(new char[writeLength]);
    memset(buf.get(), 'a', writeLength);
    WriteCallback wcb;
    socket->write(&wcb, buf.get(), writeLength);
  
    evb.loop();
  
    // Make sure the write failed.
    // It would be nice if AsyncSocketException could convey the errno value,
    // so that we could check for EPIPE
    ASSERT_EQ(wcb.state, STATE_FAILED);
    ASSERT_EQ(wcb.exception.getType(),
                      AsyncSocketException::INTERNAL_ERROR);
  
    ASSERT_FALSE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test writing to a socket that has its read side closed
   */
  TEST(AsyncSocketTest, WriteAfterReadEOF) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket =
        AsyncSocket::newSocket(&evb, server.getAddress(), 30);
    evb.loop(); // loop until the socket is connected
  
    // Accept the connection
    std::shared_ptr<AsyncSocket> acceptedSocket = server.acceptAsync(&evb);
    ReadCallback rcb;
    acceptedSocket->setReadCB(&rcb);
  
    // Shutdown the write side of client socket (read side of server socket)
    socket->shutdownWrite();
    evb.loop();
  
    // Check that accepted socket is still writable
    ASSERT_FALSE(acceptedSocket->good());
    ASSERT_TRUE(acceptedSocket->writable());
  
    // Write data to accepted socket
    constexpr size_t simpleBufLength = 5;
    char simpleBuf[simpleBufLength];
    memset(simpleBuf, 'a', simpleBufLength);
    WriteCallback wcb;
    acceptedSocket->write(&wcb, simpleBuf, simpleBufLength);
    evb.loop();
  
    // Make sure we were able to write even after getting a read EOF
    ASSERT_EQ(rcb.state, STATE_SUCCEEDED); // this indicates EOF
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  }
  
  /**
   * Test that bytes written is correctly computed in case of write failure
   */
  TEST(AsyncSocketTest, WriteErrorCallbackBytesWritten) {
    // Send and receive buffer sizes for the sockets.
    constexpr size_t kSockBufSize = 8 * 1024;
  
    TestServer server(false, kSockBufSize);
  
    AsyncSocket::OptionMap options{
        {{SOL_SOCKET, SO_SNDBUF}, kSockBufSize},
        {{SOL_SOCKET, SO_RCVBUF}, kSockBufSize},
        {{IPPROTO_TCP, TCP_NODELAY}, 1},
    };
  
    // The current thread will be used by the receiver - use a separate thread
    // for the sender.
    EventBase senderEvb;
    std::thread senderThread([&]() { senderEvb.loopForever(); });
  
    ConnCallback ccb;
    std::shared_ptr<AsyncSocket> socket;
  
    senderEvb.runInEventBaseThreadAndWait([&]() {
      socket = AsyncSocket::newSocket(&senderEvb);
      socket->connect(&ccb, server.getAddress(), 30, options);
    });
  
    // accept the socket on the server side
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
  
    // Send a big (45KB) write so that it is partially written. The first write
    // is 16KB (8KB on both sides) and subsequent writes are 8KB each. Reading
    // just under 24KB would cause 3-4 writes for the total of 32-40KB in the
    // following sequence: 16KB + 8KB + 8KB (+ 8KB). This ensures that not all
    // bytes are written when the socket is reset. Having at least 3 writes
    // ensures that the total size (45KB) would be exceeed in case of overcounting
    // based on the initial write size of 16KB.
    constexpr size_t kSendSize = 45 * 1024;
    auto const sendBuf = std::vector<char>(kSendSize, 'a');
  
    WriteCallback wcb;
  
    senderEvb.runInEventBaseThreadAndWait(
        [&]() { socket->write(&wcb, sendBuf.data(), kSendSize); });
  
    // Reading 20KB would cause three additional writes of 8KB, but less
    // than 45KB total, so the socket is reset before all bytes are written.
    constexpr size_t kRecvSize = 20 * 1024;
    uint8_t recvBuf[kRecvSize];
    int bytesRead = acceptedSocket->readAll(recvBuf, sizeof(recvBuf));
    ASSERT_EQ(kRecvSize, bytesRead);
  
    constexpr size_t kMinExpectedBytesWritten = // 20 ACK + 8 send buf
        kRecvSize + kSockBufSize;
    static_assert(kMinExpectedBytesWritten == 28 * 1024, "bad math");
    static_assert(kMinExpectedBytesWritten > kRecvSize, "bad math");
  
    constexpr size_t kMaxExpectedBytesWritten = // 24 ACK + 8 sent + 8 send buf
        constexpr_ceil(kRecvSize, kSockBufSize) + 2 * kSockBufSize;
    static_assert(kMaxExpectedBytesWritten == 40 * 1024, "bad math");
    static_assert(kMaxExpectedBytesWritten < kSendSize, "bad math");
  
    // Need to delay after receiving 20KB and before closing the receive side so
    // that the send side has a chance to fill the send buffer past.
    using clock = std::chrono::steady_clock;
    auto const deadline = clock::now() + std::chrono::seconds(2);
    while (wcb.bytesWritten < kMinExpectedBytesWritten &&
           clock::now() < deadline) {
      std::this_thread::yield();
    }
    acceptedSocket->closeWithReset();
  
    senderEvb.terminateLoopSoon();
    senderThread.join();
  
    ASSERT_EQ(STATE_FAILED, wcb.state);
    ASSERT_LE(kMinExpectedBytesWritten, wcb.bytesWritten);
    ASSERT_GE(kMaxExpectedBytesWritten, wcb.bytesWritten);
  }
  
  /**
   * Test writing a mix of simple buffers and IOBufs
   */
  TEST(AsyncSocketTest, WriteIOBuf) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Accept the connection
    std::shared_ptr<AsyncSocket> acceptedSocket = server.acceptAsync(&evb);
    ReadCallback rcb;
    acceptedSocket->setReadCB(&rcb);
  
    // Check if EOR tracking flag can be set and reset.
    EXPECT_FALSE(socket->isEorTrackingEnabled());
    socket->setEorTracking(true);
    EXPECT_TRUE(socket->isEorTrackingEnabled());
    socket->setEorTracking(false);
    EXPECT_FALSE(socket->isEorTrackingEnabled());
  
    // Write a simple buffer to the socket
    constexpr size_t simpleBufLength = 5;
    char simpleBuf[simpleBufLength];
    memset(simpleBuf, 'a', simpleBufLength);
    WriteCallback wcb;
    socket->write(&wcb, simpleBuf, simpleBufLength);
  
    // Write a single-element IOBuf chain
    size_t buf1Length = 7;
    unique_ptr<IOBuf> buf1(IOBuf::create(buf1Length));
    memset(buf1->writableData(), 'b', buf1Length);
    buf1->append(buf1Length);
    unique_ptr<IOBuf> buf1Copy(buf1->clone());
    WriteCallback wcb2;
    socket->writeChain(&wcb2, std::move(buf1));
  
    // Write a multiple-element IOBuf chain
    size_t buf2Length = 11;
    unique_ptr<IOBuf> buf2(IOBuf::create(buf2Length));
    memset(buf2->writableData(), 'c', buf2Length);
    buf2->append(buf2Length);
    size_t buf3Length = 13;
    unique_ptr<IOBuf> buf3(IOBuf::create(buf3Length));
    memset(buf3->writableData(), 'd', buf3Length);
    buf3->append(buf3Length);
    buf2->appendChain(std::move(buf3));
    unique_ptr<IOBuf> buf2Copy(buf2->clone());
    buf2Copy->coalesce();
    WriteCallback wcb3;
    socket->writeChain(&wcb3, std::move(buf2));
    socket->shutdownWrite();
  
    // Let the reads and writes run to completion
    evb.loop();
  
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb2.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb3.state, STATE_SUCCEEDED);
  
    // Make sure the reader got the right data in the right order
    ASSERT_EQ(rcb.state, STATE_SUCCEEDED);
    ASSERT_EQ(rcb.buffers.size(), 1);
    ASSERT_EQ(rcb.buffers[0].length,
        simpleBufLength + buf1Length + buf2Length + buf3Length);
    ASSERT_EQ(
        memcmp(rcb.buffers[0].buffer, simpleBuf, simpleBufLength), 0);
    ASSERT_EQ(
        memcmp(rcb.buffers[0].buffer + simpleBufLength,
            buf1Copy->data(), buf1Copy->length()), 0);
    ASSERT_EQ(
        memcmp(rcb.buffers[0].buffer + simpleBufLength + buf1Length,
            buf2Copy->data(), buf2Copy->length()), 0);
  
    acceptedSocket->close();
    socket->close();
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  TEST(AsyncSocketTest, WriteIOBufCorked) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Accept the connection
    std::shared_ptr<AsyncSocket> acceptedSocket = server.acceptAsync(&evb);
    ReadCallback rcb;
    acceptedSocket->setReadCB(&rcb);
  
    // Do three writes, 100ms apart, with the "cork" flag set
    // on the second write.  The reader should see the first write
    // arrive by itself, followed by the second and third writes
    // arriving together.
    size_t buf1Length = 5;
    unique_ptr<IOBuf> buf1(IOBuf::create(buf1Length));
    memset(buf1->writableData(), 'a', buf1Length);
    buf1->append(buf1Length);
    size_t buf2Length = 7;
    unique_ptr<IOBuf> buf2(IOBuf::create(buf2Length));
    memset(buf2->writableData(), 'b', buf2Length);
    buf2->append(buf2Length);
    size_t buf3Length = 11;
    unique_ptr<IOBuf> buf3(IOBuf::create(buf3Length));
    memset(buf3->writableData(), 'c', buf3Length);
    buf3->append(buf3Length);
    WriteCallback wcb1;
    socket->writeChain(&wcb1, std::move(buf1));
    WriteCallback wcb2;
    DelayedWrite write2(socket, std::move(buf2), &wcb2, true);
    write2.scheduleTimeout(100);
    WriteCallback wcb3;
    DelayedWrite write3(socket, std::move(buf3), &wcb3, false, true);
    write3.scheduleTimeout(140);
  
    evb.loop();
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb1.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb2.state, STATE_SUCCEEDED);
    if (wcb3.state != STATE_SUCCEEDED) {
      throw(wcb3.exception);
    }
    ASSERT_EQ(wcb3.state, STATE_SUCCEEDED);
  
    // Make sure the reader got the data with the right grouping
    ASSERT_EQ(rcb.state, STATE_SUCCEEDED);
    ASSERT_EQ(rcb.buffers.size(), 2);
    ASSERT_EQ(rcb.buffers[0].length, buf1Length);
    ASSERT_EQ(rcb.buffers[1].length, buf2Length + buf3Length);
  
    acceptedSocket->close();
    socket->close();
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test performing a zero-length write
   */
  TEST(AsyncSocketTest, ZeroLengthWrite) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket =
      AsyncSocket::newSocket(&evb, server.getAddress(), 30);
    evb.loop(); // loop until the socket is connected
  
    auto acceptedSocket = server.acceptAsync(&evb);
    ReadCallback rcb;
    acceptedSocket->setReadCB(&rcb);
  
    size_t len1 = 1024*1024;
    size_t len2 = 1024*1024;
    std::unique_ptr<char[]> buf(new char[len1 + len2]);
    memset(buf.get(), 'a', len1);
    memset(buf.get(), 'b', len2);
  
    WriteCallback wcb1;
    WriteCallback wcb2;
    WriteCallback wcb3;
    WriteCallback wcb4;
    socket->write(&wcb1, buf.get(), 0);
    socket->write(&wcb2, buf.get(), len1);
    socket->write(&wcb3, buf.get() + len1, 0);
    socket->write(&wcb4, buf.get() + len1, len2);
    socket->close();
  
    evb.loop(); // loop until the data is sent
  
    ASSERT_EQ(wcb1.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb2.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb3.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb4.state, STATE_SUCCEEDED);
    rcb.verifyData(buf.get(), len1 + len2);
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  TEST(AsyncSocketTest, ZeroLengthWritev) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket =
      AsyncSocket::newSocket(&evb, server.getAddress(), 30);
    evb.loop(); // loop until the socket is connected
  
    auto acceptedSocket = server.acceptAsync(&evb);
    ReadCallback rcb;
    acceptedSocket->setReadCB(&rcb);
  
    size_t len1 = 1024*1024;
    size_t len2 = 1024*1024;
    std::unique_ptr<char[]> buf(new char[len1 + len2]);
    memset(buf.get(), 'a', len1);
    memset(buf.get(), 'b', len2);
  
    WriteCallback wcb;
    constexpr size_t iovCount = 4;
    struct iovec iov[iovCount];
    iov[0].iov_base = buf.get();
    iov[0].iov_len = len1;
    iov[1].iov_base = buf.get() + len1;
    iov[1].iov_len = 0;
    iov[2].iov_base = buf.get() + len1;
    iov[2].iov_len = len2;
    iov[3].iov_base = buf.get() + len1 + len2;
    iov[3].iov_len = 0;
  
    socket->writev(&wcb, iov, iovCount);
    socket->close();
    evb.loop(); // loop until the data is sent
  
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
    rcb.verifyData(buf.get(), len1 + len2);
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  ///////////////////////////////////////////////////////////////////////////
  // close() related tests
  ///////////////////////////////////////////////////////////////////////////
  
  /**
   * Test calling close() with pending writes when the socket is already closing.
   */
  TEST(AsyncSocketTest, ClosePendingWritesWhileClosing) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // accept the socket on the server side
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
  
    // Loop to ensure the connect has completed
    evb.loop();
  
    // Make sure we are connected
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
  
    // Schedule pending writes, until several write attempts have blocked
    char buf[128];
    memset(buf, 'a', sizeof(buf));
    typedef vector< std::shared_ptr<WriteCallback> > WriteCallbackVector;
    WriteCallbackVector writeCallbacks;
  
    writeCallbacks.reserve(5);
    while (writeCallbacks.size() < 5) {
      std::shared_ptr<WriteCallback> wcb(new WriteCallback);
  
      socket->write(wcb.get(), buf, sizeof(buf));
      if (wcb->state == STATE_SUCCEEDED) {
        // Succeeded immediately.  Keep performing more writes
        continue;
      }
  
      // This write is blocked.
      // Have the write callback call close() when writeError() is invoked
      wcb->errorCallback = std::bind(&AsyncSocket::close, socket.get());
      writeCallbacks.push_back(wcb);
    }
  
    // Call closeNow() to immediately fail the pending writes
    socket->closeNow();
  
    // Make sure writeError() was invoked on all of the pending write callbacks
    for (WriteCallbackVector::const_iterator it = writeCallbacks.begin();
         it != writeCallbacks.end();
         ++it) {
      ASSERT_EQ((*it)->state, STATE_FAILED);
    }
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  ///////////////////////////////////////////////////////////////////////////
  // ImmediateRead related tests
  ///////////////////////////////////////////////////////////////////////////
  
  /* AsyncSocket use to verify immediate read works */
  class AsyncSocketImmediateRead : public folly::AsyncSocket {
   public:
    bool immediateReadCalled = false;
    explicit AsyncSocketImmediateRead(folly::EventBase* evb) : AsyncSocket(evb) {}
   protected:
    void checkForImmediateRead() noexcept override {
      immediateReadCalled = true;
      AsyncSocket::handleRead();
    }
  };
  
  TEST(AsyncSocket, ConnectReadImmediateRead) {
    TestServer server;
  
    const size_t maxBufferSz = 100;
    const size_t maxReadsPerEvent = 1;
    const size_t expectedDataSz = maxBufferSz * 3;
    char expectedData[expectedDataSz];
    memset(expectedData, 'j', expectedDataSz);
  
    EventBase evb;
    ReadCallback rcb(maxBufferSz);
    AsyncSocketImmediateRead socket(&evb);
    socket.connect(nullptr, server.getAddress(), 30);
  
    evb.loop(); // loop until the socket is connected
  
    socket.setReadCB(&rcb);
    socket.setMaxReadsPerEvent(maxReadsPerEvent);
    socket.immediateReadCalled = false;
  
    auto acceptedSocket = server.acceptAsync(&evb);
  
    ReadCallback rcbServer;
    WriteCallback wcbServer;
    rcbServer.dataAvailableCallback = [&]() {
      if (rcbServer.dataRead() == expectedDataSz) {
        // write back all data read
        rcbServer.verifyData(expectedData, expectedDataSz);
        acceptedSocket->write(&wcbServer, expectedData, expectedDataSz);
        acceptedSocket->close();
      }
    };
    acceptedSocket->setReadCB(&rcbServer);
  
    // write data
    WriteCallback wcb1;
    socket.write(&wcb1, expectedData, expectedDataSz);
    evb.loop();
    ASSERT_EQ(wcb1.state, STATE_SUCCEEDED);
    rcb.verifyData(expectedData, expectedDataSz);
    ASSERT_EQ(socket.immediateReadCalled, true);
  
    ASSERT_FALSE(socket.isClosedBySelf());
    ASSERT_FALSE(socket.isClosedByPeer());
  }
  
  TEST(AsyncSocket, ConnectReadUninstallRead) {
    TestServer server;
  
    const size_t maxBufferSz = 100;
    const size_t maxReadsPerEvent = 1;
    const size_t expectedDataSz = maxBufferSz * 3;
    char expectedData[expectedDataSz];
    memset(expectedData, 'k', expectedDataSz);
  
    EventBase evb;
    ReadCallback rcb(maxBufferSz);
    AsyncSocketImmediateRead socket(&evb);
    socket.connect(nullptr, server.getAddress(), 30);
  
    evb.loop(); // loop until the socket is connected
  
    socket.setReadCB(&rcb);
    socket.setMaxReadsPerEvent(maxReadsPerEvent);
    socket.immediateReadCalled = false;
  
    auto acceptedSocket = server.acceptAsync(&evb);
  
    ReadCallback rcbServer;
    WriteCallback wcbServer;
    rcbServer.dataAvailableCallback = [&]() {
      if (rcbServer.dataRead() == expectedDataSz) {
        // write back all data read
        rcbServer.verifyData(expectedData, expectedDataSz);
        acceptedSocket->write(&wcbServer, expectedData, expectedDataSz);
        acceptedSocket->close();
      }
    };
    acceptedSocket->setReadCB(&rcbServer);
  
    rcb.dataAvailableCallback = [&]() {
      // we read data and reset readCB
      socket.setReadCB(nullptr);
    };
  
    // write data
    WriteCallback wcb;
    socket.write(&wcb, expectedData, expectedDataSz);
    evb.loop();
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  
    /* we shoud've only read maxBufferSz data since readCallback_
     * was reset in dataAvailableCallback */
    ASSERT_EQ(rcb.dataRead(), maxBufferSz);
    ASSERT_EQ(socket.immediateReadCalled, false);
  
    ASSERT_FALSE(socket.isClosedBySelf());
    ASSERT_FALSE(socket.isClosedByPeer());
  }
  
  // TODO:
  // - Test connect() and have the connect callback set the read callback
  // - Test connect() and have the connect callback unset the read callback
  // - Test reading/writing/closing/destroying the socket in the connect callback
  // - Test reading/writing/closing/destroying the socket in the read callback
  // - Test reading/writing/closing/destroying the socket in the write callback
  // - Test one-way shutdown behavior
  // - Test changing the EventBase
  //
  // - TODO: test multiple threads sharing a AsyncSocket, and detaching from it
  //   in connectSuccess(), readDataAvailable(), writeSuccess()
  
  
  ///////////////////////////////////////////////////////////////////////////
  // AsyncServerSocket tests
  ///////////////////////////////////////////////////////////////////////////
  
  /**
   * Make sure accepted sockets have O_NONBLOCK and TCP_NODELAY set
   */
  TEST(AsyncSocketTest, ServerAcceptOptions) {
    EventBase eventBase;
  
    // Create a server socket
    std::shared_ptr<AsyncServerSocket> serverSocket(
        AsyncServerSocket::newSocket(&eventBase));
    serverSocket->bind(0);
    serverSocket->listen(16);
    folly::SocketAddress serverAddress;
    serverSocket->getAddress(&serverAddress);
  
    // Add a callback to accept one connection then stop the loop
    TestAcceptCallback acceptCallback;
    acceptCallback.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          serverSocket->removeAcceptCallback(&acceptCallback, &eventBase);
        });
    acceptCallback.setAcceptErrorFn([&](const std::exception& /* ex */) {
      serverSocket->removeAcceptCallback(&acceptCallback, &eventBase);
    });
    serverSocket->addAcceptCallback(&acceptCallback, &eventBase);
    serverSocket->startAccepting();
  
    // Connect to the server socket
    std::shared_ptr<AsyncSocket> socket(
        AsyncSocket::newSocket(&eventBase, serverAddress));
  
    eventBase.loop();
  
    // Verify that the server accepted a connection
    ASSERT_EQ(acceptCallback.getEvents()->size(), 3);
    ASSERT_EQ(acceptCallback.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(acceptCallback.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(acceptCallback.getEvents()->at(2).type,
                      TestAcceptCallback::TYPE_STOP);
    int fd = acceptCallback.getEvents()->at(1).fd;
  
    // The accepted connection should already be in non-blocking mode
    int flags = fcntl(fd, F_GETFL, 0);
    ASSERT_EQ(flags & O_NONBLOCK, O_NONBLOCK);
  
  #ifndef TCP_NOPUSH
    // The accepted connection should already have TCP_NODELAY set
    int value;
    socklen_t valueLength = sizeof(value);
    int rc = getsockopt(fd, IPPROTO_TCP, TCP_NODELAY, &value, &valueLength);
    ASSERT_EQ(rc, 0);
    ASSERT_EQ(value, 1);
  #endif
  }
  
  /**
   * Test AsyncServerSocket::removeAcceptCallback()
   */
  TEST(AsyncSocketTest, RemoveAcceptCallback) {
    // Create a new AsyncServerSocket
    EventBase eventBase;
    std::shared_ptr<AsyncServerSocket> serverSocket(
        AsyncServerSocket::newSocket(&eventBase));
    serverSocket->bind(0);
    serverSocket->listen(16);
    folly::SocketAddress serverAddress;
    serverSocket->getAddress(&serverAddress);
  
    // Add several accept callbacks
    TestAcceptCallback cb1;
    TestAcceptCallback cb2;
    TestAcceptCallback cb3;
    TestAcceptCallback cb4;
    TestAcceptCallback cb5;
    TestAcceptCallback cb6;
    TestAcceptCallback cb7;
  
    // Test having callbacks remove other callbacks before them on the list,
    // after them on the list, or removing themselves.
    //
    // Have callback 2 remove callback 3 and callback 5 the first time it is
    // called.
    int cb2Count = 0;
    cb1.setConnectionAcceptedFn([&](int /* fd */,
                                    const folly::SocketAddress& /* addr */) {
      std::shared_ptr<AsyncSocket> sock2(
          AsyncSocket::newSocket(&eventBase, serverAddress)); // cb2: -cb3 -cb5
    });
    cb3.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {});
    cb4.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          std::shared_ptr<AsyncSocket> sock3(
              AsyncSocket::newSocket(&eventBase, serverAddress)); // cb4
        });
    cb5.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          std::shared_ptr<AsyncSocket> sock5(
              AsyncSocket::newSocket(&eventBase, serverAddress)); // cb7: -cb7
  
        });
    cb2.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          if (cb2Count == 0) {
            serverSocket->removeAcceptCallback(&cb3, nullptr);
            serverSocket->removeAcceptCallback(&cb5, nullptr);
          }
          ++cb2Count;
        });
    // Have callback 6 remove callback 4 the first time it is called,
    // and destroy the server socket the second time it is called
    int cb6Count = 0;
    cb6.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          if (cb6Count == 0) {
            serverSocket->removeAcceptCallback(&cb4, nullptr);
            std::shared_ptr<AsyncSocket> sock6(
                AsyncSocket::newSocket(&eventBase, serverAddress)); // cb1
            std::shared_ptr<AsyncSocket> sock7(
                AsyncSocket::newSocket(&eventBase, serverAddress)); // cb2
            std::shared_ptr<AsyncSocket> sock8(
                AsyncSocket::newSocket(&eventBase, serverAddress)); // cb6: stop
  
          } else {
            serverSocket.reset();
          }
          ++cb6Count;
        });
    // Have callback 7 remove itself
    cb7.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          serverSocket->removeAcceptCallback(&cb7, nullptr);
        });
  
    serverSocket->addAcceptCallback(&cb1, &eventBase);
    serverSocket->addAcceptCallback(&cb2, &eventBase);
    serverSocket->addAcceptCallback(&cb3, &eventBase);
    serverSocket->addAcceptCallback(&cb4, &eventBase);
    serverSocket->addAcceptCallback(&cb5, &eventBase);
    serverSocket->addAcceptCallback(&cb6, &eventBase);
    serverSocket->addAcceptCallback(&cb7, &eventBase);
    serverSocket->startAccepting();
  
    // Make several connections to the socket
    std::shared_ptr<AsyncSocket> sock1(
        AsyncSocket::newSocket(&eventBase, serverAddress)); // cb1
    std::shared_ptr<AsyncSocket> sock4(
        AsyncSocket::newSocket(&eventBase, serverAddress)); // cb6: -cb4
  
    // Loop until we are stopped
    eventBase.loop();
  
    // Check to make sure that the expected callbacks were invoked.
    //
    // NOTE: This code depends on the AsyncServerSocket operating calling all of
    // the AcceptCallbacks in round-robin fashion, in the order that they were
    // added.  The code is implemented this way right now, but the API doesn't
    // explicitly require it be done this way.  If we change the code not to be
    // exactly round robin in the future, we can simplify the test checks here.
    // (We'll also need to update the termination code, since we expect cb6 to
    // get called twice to terminate the loop.)
    ASSERT_EQ(cb1.getEvents()->size(), 4);
    ASSERT_EQ(cb1.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(cb1.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(cb1.getEvents()->at(2).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(cb1.getEvents()->at(3).type,
                      TestAcceptCallback::TYPE_STOP);
  
    ASSERT_EQ(cb2.getEvents()->size(), 4);
    ASSERT_EQ(cb2.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(cb2.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(cb2.getEvents()->at(2).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(cb2.getEvents()->at(3).type,
                      TestAcceptCallback::TYPE_STOP);
  
    ASSERT_EQ(cb3.getEvents()->size(), 2);
    ASSERT_EQ(cb3.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(cb3.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_STOP);
  
    ASSERT_EQ(cb4.getEvents()->size(), 3);
    ASSERT_EQ(cb4.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(cb4.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(cb4.getEvents()->at(2).type,
                      TestAcceptCallback::TYPE_STOP);
  
    ASSERT_EQ(cb5.getEvents()->size(), 2);
    ASSERT_EQ(cb5.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(cb5.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_STOP);
  
    ASSERT_EQ(cb6.getEvents()->size(), 4);
    ASSERT_EQ(cb6.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(cb6.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(cb6.getEvents()->at(2).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(cb6.getEvents()->at(3).type,
                      TestAcceptCallback::TYPE_STOP);
  
    ASSERT_EQ(cb7.getEvents()->size(), 3);
    ASSERT_EQ(cb7.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(cb7.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(cb7.getEvents()->at(2).type,
                      TestAcceptCallback::TYPE_STOP);
  }
  
  /**
   * Test AsyncServerSocket::removeAcceptCallback()
   */
  TEST(AsyncSocketTest, OtherThreadAcceptCallback) {
    // Create a new AsyncServerSocket
    EventBase eventBase;
    std::shared_ptr<AsyncServerSocket> serverSocket(
        AsyncServerSocket::newSocket(&eventBase));
    serverSocket->bind(0);
    serverSocket->listen(16);
    folly::SocketAddress serverAddress;
    serverSocket->getAddress(&serverAddress);
  
    // Add several accept callbacks
    TestAcceptCallback cb1;
    auto thread_id = std::this_thread::get_id();
    cb1.setAcceptStartedFn([&](){
      CHECK_NE(thread_id, std::this_thread::get_id());
      thread_id = std::this_thread::get_id();
    });
    cb1.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          ASSERT_EQ(thread_id, std::this_thread::get_id());
          serverSocket->removeAcceptCallback(&cb1, &eventBase);
        });
    cb1.setAcceptStoppedFn([&](){
      ASSERT_EQ(thread_id, std::this_thread::get_id());
    });
  
    // Test having callbacks remove other callbacks before them on the list,
    serverSocket->addAcceptCallback(&cb1, &eventBase);
    serverSocket->startAccepting();
  
    // Make several connections to the socket
    std::shared_ptr<AsyncSocket> sock1(
        AsyncSocket::newSocket(&eventBase, serverAddress)); // cb1
  
    // Loop in another thread
    auto other = std::thread([&](){
      eventBase.loop();
    });
    other.join();
  
    // Check to make sure that the expected callbacks were invoked.
    //
    // NOTE: This code depends on the AsyncServerSocket operating calling all of
    // the AcceptCallbacks in round-robin fashion, in the order that they were
    // added.  The code is implemented this way right now, but the API doesn't
    // explicitly require it be done this way.  If we change the code not to be
    // exactly round robin in the future, we can simplify the test checks here.
    // (We'll also need to update the termination code, since we expect cb6 to
    // get called twice to terminate the loop.)
    ASSERT_EQ(cb1.getEvents()->size(), 3);
    ASSERT_EQ(cb1.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(cb1.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(cb1.getEvents()->at(2).type,
                      TestAcceptCallback::TYPE_STOP);
  
  }
  
  void serverSocketSanityTest(AsyncServerSocket* serverSocket) {
    EventBase* eventBase = serverSocket->getEventBase();
    CHECK(eventBase);
  
    // Add a callback to accept one connection then stop accepting
    TestAcceptCallback acceptCallback;
    acceptCallback.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          serverSocket->removeAcceptCallback(&acceptCallback, eventBase);
        });
    acceptCallback.setAcceptErrorFn([&](const std::exception& /* ex */) {
      serverSocket->removeAcceptCallback(&acceptCallback, eventBase);
    });
    serverSocket->addAcceptCallback(&acceptCallback, eventBase);
    serverSocket->startAccepting();
  
    // Connect to the server socket
    folly::SocketAddress serverAddress;
    serverSocket->getAddress(&serverAddress);
    AsyncSocket::UniquePtr socket(new AsyncSocket(eventBase, serverAddress));
  
    // Loop to process all events
    eventBase->loop();
  
    // Verify that the server accepted a connection
    ASSERT_EQ(acceptCallback.getEvents()->size(), 3);
    ASSERT_EQ(acceptCallback.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(acceptCallback.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(acceptCallback.getEvents()->at(2).type,
                      TestAcceptCallback::TYPE_STOP);
  }
  
  /* Verify that we don't leak sockets if we are destroyed()
   * and there are still writes pending
   *
   * If destroy() only calls close() instead of closeNow(),
   * it would shutdown(writes) on the socket, but it would
   * never be close()'d, and the socket would leak
   */
  TEST(AsyncSocketTest, DestroyCloseTest) {
    TestServer server;
  
    // connect()
    EventBase clientEB;
    EventBase serverEB;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&clientEB);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // Accept the connection
    std::shared_ptr<AsyncSocket> acceptedSocket = server.acceptAsync(&serverEB);
    ReadCallback rcb;
    acceptedSocket->setReadCB(&rcb);
  
    // Write a large buffer to the socket that is larger than kernel buffer
    size_t simpleBufLength = 5000000;
    char* simpleBuf = new char[simpleBufLength];
    memset(simpleBuf, 'a', simpleBufLength);
    WriteCallback wcb;
  
    // Let the reads and writes run to completion
    int fd = acceptedSocket->getFd();
  
    acceptedSocket->write(&wcb, simpleBuf, simpleBufLength);
    socket.reset();
    acceptedSocket.reset();
  
    // Test that server socket was closed
    folly::test::msvcSuppressAbortOnInvalidParams([&] {
      ssize_t sz = read(fd, simpleBuf, simpleBufLength);
      ASSERT_EQ(sz, -1);
      ASSERT_EQ(errno, EBADF);
    });
    delete[] simpleBuf;
  }
  
  /**
   * Test AsyncServerSocket::useExistingSocket()
   */
  TEST(AsyncSocketTest, ServerExistingSocket) {
    EventBase eventBase;
  
    // Test creating a socket, and letting AsyncServerSocket bind and listen
    {
      // Manually create a socket
      int fd = fsp::socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
      ASSERT_GE(fd, 0);
  
      // Create a server socket
      AsyncServerSocket::UniquePtr serverSocket(
          new AsyncServerSocket(&eventBase));
      serverSocket->useExistingSocket(fd);
      folly::SocketAddress address;
      serverSocket->getAddress(&address);
      address.setPort(0);
      serverSocket->bind(address);
      serverSocket->listen(16);
  
      // Make sure the socket works
      serverSocketSanityTest(serverSocket.get());
    }
  
    // Test creating a socket and binding manually,
    // then letting AsyncServerSocket listen
    {
      // Manually create a socket
      int fd = fsp::socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
      ASSERT_GE(fd, 0);
      // bind
      struct sockaddr_in addr;
      addr.sin_family = AF_INET;
      addr.sin_port = 0;
      addr.sin_addr.s_addr = INADDR_ANY;
      ASSERT_EQ(bind(fd, reinterpret_cast<struct sockaddr*>(&addr),
                               sizeof(addr)), 0);
      // Look up the address that we bound to
      folly::SocketAddress boundAddress;
      boundAddress.setFromLocalAddress(fd);
  
      // Create a server socket
      AsyncServerSocket::UniquePtr serverSocket(
          new AsyncServerSocket(&eventBase));
      serverSocket->useExistingSocket(fd);
      serverSocket->listen(16);
  
      // Make sure AsyncServerSocket reports the same address that we bound to
      folly::SocketAddress serverSocketAddress;
      serverSocket->getAddress(&serverSocketAddress);
      ASSERT_EQ(boundAddress, serverSocketAddress);
  
      // Make sure the socket works
      serverSocketSanityTest(serverSocket.get());
    }
  
    // Test creating a socket, binding and listening manually,
    // then giving it to AsyncServerSocket
    {
      // Manually create a socket
      int fd = fsp::socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
      ASSERT_GE(fd, 0);
      // bind
      struct sockaddr_in addr;
      addr.sin_family = AF_INET;
      addr.sin_port = 0;
      addr.sin_addr.s_addr = INADDR_ANY;
      ASSERT_EQ(bind(fd, reinterpret_cast<struct sockaddr*>(&addr),
                               sizeof(addr)), 0);
      // Look up the address that we bound to
      folly::SocketAddress boundAddress;
      boundAddress.setFromLocalAddress(fd);
      // listen
      ASSERT_EQ(listen(fd, 16), 0);
  
      // Create a server socket
      AsyncServerSocket::UniquePtr serverSocket(
          new AsyncServerSocket(&eventBase));
      serverSocket->useExistingSocket(fd);
  
      // Make sure AsyncServerSocket reports the same address that we bound to
      folly::SocketAddress serverSocketAddress;
      serverSocket->getAddress(&serverSocketAddress);
      ASSERT_EQ(boundAddress, serverSocketAddress);
  
      // Make sure the socket works
      serverSocketSanityTest(serverSocket.get());
    }
  }
  
  TEST(AsyncSocketTest, UnixDomainSocketTest) {
    EventBase eventBase;
  
    // Create a server socket
    std::shared_ptr<AsyncServerSocket> serverSocket(
        AsyncServerSocket::newSocket(&eventBase));
    string path(1, 0);
    path.append(folly::to<string>("/anonymous", folly::Random::rand64()));
    folly::SocketAddress serverAddress;
    serverAddress.setFromPath(path);
    serverSocket->bind(serverAddress);
    serverSocket->listen(16);
  
    // Add a callback to accept one connection then stop the loop
    TestAcceptCallback acceptCallback;
    acceptCallback.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          serverSocket->removeAcceptCallback(&acceptCallback, &eventBase);
        });
    acceptCallback.setAcceptErrorFn([&](const std::exception& /* ex */) {
      serverSocket->removeAcceptCallback(&acceptCallback, &eventBase);
    });
    serverSocket->addAcceptCallback(&acceptCallback, &eventBase);
    serverSocket->startAccepting();
  
    // Connect to the server socket
    std::shared_ptr<AsyncSocket> socket(
        AsyncSocket::newSocket(&eventBase, serverAddress));
  
    eventBase.loop();
  
    // Verify that the server accepted a connection
    ASSERT_EQ(acceptCallback.getEvents()->size(), 3);
    ASSERT_EQ(acceptCallback.getEvents()->at(0).type,
                      TestAcceptCallback::TYPE_START);
    ASSERT_EQ(acceptCallback.getEvents()->at(1).type,
                      TestAcceptCallback::TYPE_ACCEPT);
    ASSERT_EQ(acceptCallback.getEvents()->at(2).type,
                      TestAcceptCallback::TYPE_STOP);
    int fd = acceptCallback.getEvents()->at(1).fd;
  
    // The accepted connection should already be in non-blocking mode
    int flags = fcntl(fd, F_GETFL, 0);
    ASSERT_EQ(flags & O_NONBLOCK, O_NONBLOCK);
  }
  
  TEST(AsyncSocketTest, ConnectionEventCallbackDefault) {
    EventBase eventBase;
    TestConnectionEventCallback connectionEventCallback;
  
    // Create a server socket
    std::shared_ptr<AsyncServerSocket> serverSocket(
        AsyncServerSocket::newSocket(&eventBase));
    serverSocket->setConnectionEventCallback(&connectionEventCallback);
    serverSocket->bind(0);
    serverSocket->listen(16);
    folly::SocketAddress serverAddress;
    serverSocket->getAddress(&serverAddress);
  
    // Add a callback to accept one connection then stop the loop
    TestAcceptCallback acceptCallback;
    acceptCallback.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          serverSocket->removeAcceptCallback(&acceptCallback, nullptr);
        });
    acceptCallback.setAcceptErrorFn([&](const std::exception& /* ex */) {
      serverSocket->removeAcceptCallback(&acceptCallback, nullptr);
    });
    serverSocket->addAcceptCallback(&acceptCallback, &eventBase);
    serverSocket->startAccepting();
  
    // Connect to the server socket
    std::shared_ptr<AsyncSocket> socket(
        AsyncSocket::newSocket(&eventBase, serverAddress));
  
    eventBase.loop();
  
    // Validate the connection event counters
    ASSERT_EQ(connectionEventCallback.getConnectionAccepted(), 1);
    ASSERT_EQ(connectionEventCallback.getConnectionAcceptedError(), 0);
    ASSERT_EQ(connectionEventCallback.getConnectionDropped(), 0);
    ASSERT_EQ(
        connectionEventCallback.getConnectionEnqueuedForAcceptCallback(), 1);
    ASSERT_EQ(connectionEventCallback.getConnectionDequeuedByAcceptCallback(), 1);
    ASSERT_EQ(connectionEventCallback.getBackoffStarted(), 0);
    ASSERT_EQ(connectionEventCallback.getBackoffEnded(), 0);
    ASSERT_EQ(connectionEventCallback.getBackoffError(), 0);
  }
  
  TEST(AsyncSocketTest, CallbackInPrimaryEventBase) {
    EventBase eventBase;
    TestConnectionEventCallback connectionEventCallback;
  
    // Create a server socket
    std::shared_ptr<AsyncServerSocket> serverSocket(
        AsyncServerSocket::newSocket(&eventBase));
    serverSocket->setConnectionEventCallback(&connectionEventCallback);
    serverSocket->bind(0);
    serverSocket->listen(16);
    folly::SocketAddress serverAddress;
    serverSocket->getAddress(&serverAddress);
  
    // Add a callback to accept one connection then stop the loop
    TestAcceptCallback acceptCallback;
    acceptCallback.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          serverSocket->removeAcceptCallback(&acceptCallback, nullptr);
        });
    acceptCallback.setAcceptErrorFn([&](const std::exception& /* ex */) {
      serverSocket->removeAcceptCallback(&acceptCallback, nullptr);
    });
    bool acceptStartedFlag{false};
    acceptCallback.setAcceptStartedFn([&acceptStartedFlag](){
      acceptStartedFlag = true;
    });
    bool acceptStoppedFlag{false};
    acceptCallback.setAcceptStoppedFn([&acceptStoppedFlag](){
      acceptStoppedFlag = true;
    });
    serverSocket->addAcceptCallback(&acceptCallback, nullptr);
    serverSocket->startAccepting();
  
    // Connect to the server socket
    std::shared_ptr<AsyncSocket> socket(
        AsyncSocket::newSocket(&eventBase, serverAddress));
  
    eventBase.loop();
  
    ASSERT_TRUE(acceptStartedFlag);
    ASSERT_TRUE(acceptStoppedFlag);
    // Validate the connection event counters
    ASSERT_EQ(connectionEventCallback.getConnectionAccepted(), 1);
    ASSERT_EQ(connectionEventCallback.getConnectionAcceptedError(), 0);
    ASSERT_EQ(connectionEventCallback.getConnectionDropped(), 0);
    ASSERT_EQ(
        connectionEventCallback.getConnectionEnqueuedForAcceptCallback(), 0);
    ASSERT_EQ(connectionEventCallback.getConnectionDequeuedByAcceptCallback(), 0);
    ASSERT_EQ(connectionEventCallback.getBackoffStarted(), 0);
    ASSERT_EQ(connectionEventCallback.getBackoffEnded(), 0);
    ASSERT_EQ(connectionEventCallback.getBackoffError(), 0);
  }
  
  
  
  /**
   * Test AsyncServerSocket::getNumPendingMessagesInQueue()
   */
  TEST(AsyncSocketTest, NumPendingMessagesInQueue) {
    EventBase eventBase;
  
    // Counter of how many connections have been accepted
    int count = 0;
  
    // Create a server socket
    auto serverSocket(AsyncServerSocket::newSocket(&eventBase));
    serverSocket->bind(0);
    serverSocket->listen(16);
    folly::SocketAddress serverAddress;
    serverSocket->getAddress(&serverAddress);
  
    // Add a callback to accept connections
    TestAcceptCallback acceptCallback;
    acceptCallback.setConnectionAcceptedFn(
        [&](int /* fd */, const folly::SocketAddress& /* addr */) {
          count++;
          ASSERT_EQ(4 - count, serverSocket->getNumPendingMessagesInQueue());
  
          if (count == 4) {
            // all messages are processed, remove accept callback
            serverSocket->removeAcceptCallback(&acceptCallback, &eventBase);
          }
        });
    acceptCallback.setAcceptErrorFn([&](const std::exception& /* ex */) {
      serverSocket->removeAcceptCallback(&acceptCallback, &eventBase);
    });
    serverSocket->addAcceptCallback(&acceptCallback, &eventBase);
    serverSocket->startAccepting();
  
    // Connect to the server socket, 4 clients, there are 4 connections
    auto socket1(AsyncSocket::newSocket(&eventBase, serverAddress));
    auto socket2(AsyncSocket::newSocket(&eventBase, serverAddress));
    auto socket3(AsyncSocket::newSocket(&eventBase, serverAddress));
    auto socket4(AsyncSocket::newSocket(&eventBase, serverAddress));
  
    eventBase.loop();
  }
  
  /**
   * Test AsyncTransport::BufferCallback
   */
  TEST(AsyncSocketTest, BufferTest) {
    TestServer server;
  
    EventBase evb;
    AsyncSocket::OptionMap option{{{SOL_SOCKET, SO_SNDBUF}, 128}};
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30, option);
  
    char buf[100 * 1024];
    memset(buf, 'c', sizeof(buf));
    WriteCallback wcb;
    BufferCallback bcb;
    socket->setBufferCallback(&bcb);
    socket->write(&wcb, buf, sizeof(buf), WriteFlags::NONE);
  
    evb.loop();
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  
    ASSERT_TRUE(bcb.hasBuffered());
    ASSERT_TRUE(bcb.hasBufferCleared());
  
    socket->close();
    server.verifyConnection(buf, sizeof(buf));
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  TEST(AsyncSocketTest, BufferCallbackKill) {
    TestServer server;
    EventBase evb;
    AsyncSocket::OptionMap option{{{SOL_SOCKET, SO_SNDBUF}, 128}};
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30, option);
    evb.loopOnce();
  
    char buf[100 * 1024];
    memset(buf, 'c', sizeof(buf));
    BufferCallback bcb;
    socket->setBufferCallback(&bcb);
    WriteCallback wcb;
    wcb.successCallback = [&] {
      ASSERT_TRUE(socket.unique());
      socket.reset();
    };
  
    // This will trigger AsyncSocket::handleWrite,
    // which calls WriteCallback::writeSuccess,
    // which calls wcb.successCallback above,
    // which tries to delete socket
    // Then, the socket will also try to use this BufferCallback
    // And that should crash us, if there is no DestructorGuard on the stack
    socket->write(&wcb, buf, sizeof(buf), WriteFlags::NONE);
  
    evb.loop();
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
  }
  
  #if FOLLY_ALLOW_TFO
  TEST(AsyncSocketTest, ConnectTFO) {
    // Start listening on a local port
    TestServer server(true);
  
    // Connect using a AsyncSocket
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    socket->enableTFO();
    ConnCallback cb;
    socket->connect(&cb, server.getAddress(), 30);
  
    std::array<uint8_t, 128> buf;
    memset(buf.data(), 'a', buf.size());
  
    std::array<uint8_t, 3> readBuf;
    auto sendBuf = IOBuf::copyBuffer("hey");
  
    std::thread t([&] {
      auto acceptedSocket = server.accept();
      acceptedSocket->write(buf.data(), buf.size());
      acceptedSocket->flush();
      acceptedSocket->readAll(readBuf.data(), readBuf.size());
      acceptedSocket->close();
    });
  
    evb.loop();
  
    ASSERT_EQ(cb.state, STATE_SUCCEEDED);
    EXPECT_LE(0, socket->getConnectTime().count());
    EXPECT_EQ(socket->getConnectTimeout(), std::chrono::milliseconds(30));
    EXPECT_TRUE(socket->getTFOAttempted());
  
    // Should trigger the connect
    WriteCallback write;
    ReadCallback rcb;
    socket->writeChain(&write, sendBuf->clone());
    socket->setReadCB(&rcb);
    evb.loop();
  
    t.join();
  
    EXPECT_EQ(STATE_SUCCEEDED, write.state);
    EXPECT_EQ(0, memcmp(readBuf.data(), sendBuf->data(), readBuf.size()));
    EXPECT_EQ(STATE_SUCCEEDED, rcb.state);
    ASSERT_EQ(1, rcb.buffers.size());
    ASSERT_EQ(sizeof(buf), rcb.buffers[0].length);
    EXPECT_EQ(0, memcmp(rcb.buffers[0].buffer, buf.data(), buf.size()));
    EXPECT_EQ(socket->getTFOFinished(), socket->getTFOSucceded());
  }
  
  TEST(AsyncSocketTest, ConnectTFOSupplyEarlyReadCB) {
    // Start listening on a local port
    TestServer server(true);
  
    // Connect using a AsyncSocket
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    socket->enableTFO();
    ConnCallback cb;
    socket->connect(&cb, server.getAddress(), 30);
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    std::array<uint8_t, 128> buf;
    memset(buf.data(), 'a', buf.size());
  
    std::array<uint8_t, 3> readBuf;
    auto sendBuf = IOBuf::copyBuffer("hey");
  
    std::thread t([&] {
      auto acceptedSocket = server.accept();
      acceptedSocket->write(buf.data(), buf.size());
      acceptedSocket->flush();
      acceptedSocket->readAll(readBuf.data(), readBuf.size());
      acceptedSocket->close();
    });
  
    evb.loop();
  
    ASSERT_EQ(cb.state, STATE_SUCCEEDED);
    EXPECT_LE(0, socket->getConnectTime().count());
    EXPECT_EQ(socket->getConnectTimeout(), std::chrono::milliseconds(30));
    EXPECT_TRUE(socket->getTFOAttempted());
  
    // Should trigger the connect
    WriteCallback write;
    socket->writeChain(&write, sendBuf->clone());
    evb.loop();
  
    t.join();
  
    EXPECT_EQ(STATE_SUCCEEDED, write.state);
    EXPECT_EQ(0, memcmp(readBuf.data(), sendBuf->data(), readBuf.size()));
    EXPECT_EQ(STATE_SUCCEEDED, rcb.state);
    ASSERT_EQ(1, rcb.buffers.size());
    ASSERT_EQ(sizeof(buf), rcb.buffers[0].length);
    EXPECT_EQ(0, memcmp(rcb.buffers[0].buffer, buf.data(), buf.size()));
    EXPECT_EQ(socket->getTFOFinished(), socket->getTFOSucceded());
  }
  
  /**
   * Test connecting to a server that isn't listening
   */
  TEST(AsyncSocketTest, ConnectRefusedImmediatelyTFO) {
    EventBase evb;
  
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
  
    socket->enableTFO();
  
    // Hopefully nothing is actually listening on this address
    folly::SocketAddress addr("::1", 65535);
    ConnCallback cb;
    socket->connect(&cb, addr, 30);
  
    evb.loop();
  
    WriteCallback write1;
    // Trigger the connect if TFO attempt is supported.
    socket->writeChain(&write1, IOBuf::copyBuffer("hey"));
    WriteCallback write2;
    socket->writeChain(&write2, IOBuf::copyBuffer("hey"));
    evb.loop();
  
    if (!socket->getTFOFinished()) {
      EXPECT_EQ(STATE_FAILED, write1.state);
    } else {
      EXPECT_EQ(STATE_SUCCEEDED, write1.state);
      EXPECT_FALSE(socket->getTFOSucceded());
    }
  
    EXPECT_EQ(STATE_FAILED, write2.state);
  
    EXPECT_EQ(STATE_SUCCEEDED, cb.state);
    EXPECT_LE(0, socket->getConnectTime().count());
    EXPECT_EQ(std::chrono::milliseconds(30), socket->getConnectTimeout());
    EXPECT_TRUE(socket->getTFOAttempted());
  }
  
  /**
   * Test calling closeNow() immediately after connecting.
   */
  TEST(AsyncSocketTest, ConnectWriteAndCloseNowTFO) {
    TestServer server(true);
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    socket->enableTFO();
  
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    // write()
    std::array<char, 128> buf;
    memset(buf.data(), 'a', buf.size());
  
    // close()
    socket->closeNow();
  
    // Loop, although there shouldn't be anything to do.
    evb.loop();
  
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  /**
   * Test calling close() immediately after connect()
   */
  TEST(AsyncSocketTest, ConnectAndCloseTFO) {
    TestServer server(true);
  
    // Connect using a AsyncSocket
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    socket->enableTFO();
  
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    socket->close();
  
    // Loop, although there shouldn't be anything to do.
    evb.loop();
  
    // Make sure the connection was aborted
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  class MockAsyncTFOSocket : public AsyncSocket {
   public:
    using UniquePtr = std::unique_ptr<MockAsyncTFOSocket, Destructor>;
  
    explicit MockAsyncTFOSocket(EventBase* evb) : AsyncSocket(evb) {}
  
    MOCK_METHOD3(tfoSendMsg, ssize_t(int fd, struct msghdr* msg, int msg_flags));
  };
  
  TEST(AsyncSocketTest, TestTFOUnsupported) {
    TestServer server(true);
  
    // Connect using a AsyncSocket
    EventBase evb;
    auto socket = MockAsyncTFOSocket::UniquePtr(new MockAsyncTFOSocket(&evb));
    socket->enableTFO();
  
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
  
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    EXPECT_CALL(*socket, tfoSendMsg(_, _, _))
        .WillOnce(SetErrnoAndReturn(EOPNOTSUPP, -1));
    WriteCallback write;
    auto sendBuf = IOBuf::copyBuffer("hey");
    socket->writeChain(&write, sendBuf->clone());
    EXPECT_EQ(STATE_WAITING, write.state);
  
    std::array<uint8_t, 128> buf;
    memset(buf.data(), 'a', buf.size());
  
    std::array<uint8_t, 3> readBuf;
  
    std::thread t([&] {
      std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
      acceptedSocket->write(buf.data(), buf.size());
      acceptedSocket->flush();
      acceptedSocket->readAll(readBuf.data(), readBuf.size());
      acceptedSocket->close();
    });
  
    evb.loop();
  
    t.join();
    EXPECT_EQ(STATE_SUCCEEDED, ccb.state);
    EXPECT_EQ(STATE_SUCCEEDED, write.state);
  
    EXPECT_EQ(0, memcmp(readBuf.data(), sendBuf->data(), readBuf.size()));
    EXPECT_EQ(STATE_SUCCEEDED, rcb.state);
    ASSERT_EQ(1, rcb.buffers.size());
    ASSERT_EQ(sizeof(buf), rcb.buffers[0].length);
    EXPECT_EQ(0, memcmp(rcb.buffers[0].buffer, buf.data(), buf.size()));
    EXPECT_EQ(socket->getTFOFinished(), socket->getTFOSucceded());
  }
  
  TEST(AsyncSocketTest, ConnectRefusedDelayedTFO) {
    EventBase evb;
  
    auto socket = MockAsyncTFOSocket::UniquePtr(new MockAsyncTFOSocket(&evb));
    socket->enableTFO();
  
    // Hopefully this fails
    folly::SocketAddress fakeAddr("127.0.0.1", 65535);
    EXPECT_CALL(*socket, tfoSendMsg(_, _, _))
        .WillOnce(Invoke([&](int fd, struct msghdr*, int) {
          sockaddr_storage addr;
          auto len = fakeAddr.getAddress(&addr);
          int ret = connect(fd, (const struct sockaddr*)&addr, len);
          LOG(INFO) << "connecting the socket " << fd << " : " << ret << " : "
                    << errno;
          return ret;
        }));
  
    // Hopefully nothing is actually listening on this address
    ConnCallback cb;
    socket->connect(&cb, fakeAddr, 30);
  
    WriteCallback write1;
    // Trigger the connect if TFO attempt is supported.
    socket->writeChain(&write1, IOBuf::copyBuffer("hey"));
  
    if (socket->getTFOFinished()) {
      // This test is useless now.
      return;
    }
    WriteCallback write2;
    // Trigger the connect if TFO attempt is supported.
    socket->writeChain(&write2, IOBuf::copyBuffer("hey"));
    evb.loop();
  
    EXPECT_EQ(STATE_FAILED, write1.state);
    EXPECT_EQ(STATE_FAILED, write2.state);
    EXPECT_FALSE(socket->getTFOSucceded());
  
    EXPECT_EQ(STATE_SUCCEEDED, cb.state);
    EXPECT_LE(0, socket->getConnectTime().count());
    EXPECT_EQ(std::chrono::milliseconds(30), socket->getConnectTimeout());
    EXPECT_TRUE(socket->getTFOAttempted());
  }
  
  TEST(AsyncSocketTest, TestTFOUnsupportedTimeout) {
    // Try connecting to server that won't respond.
    //
    // This depends somewhat on the network where this test is run.
    // Hopefully this IP will be routable but unresponsive.
    // (Alternatively, we could try listening on a local raw socket, but that
    // normally requires root privileges.)
    auto host = SocketAddressTestHelper::isIPv6Enabled()
        ? SocketAddressTestHelper::kGooglePublicDnsAAddrIPv6
        : SocketAddressTestHelper::isIPv4Enabled()
            ? SocketAddressTestHelper::kGooglePublicDnsAAddrIPv4
            : nullptr;
    SocketAddress addr(host, 65535);
  
    // Connect using a AsyncSocket
    EventBase evb;
    auto socket = MockAsyncTFOSocket::UniquePtr(new MockAsyncTFOSocket(&evb));
    socket->enableTFO();
  
    ConnCallback ccb;
    // Set a very small timeout
    socket->connect(&ccb, addr, 1);
    EXPECT_EQ(STATE_SUCCEEDED, ccb.state);
  
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    EXPECT_CALL(*socket, tfoSendMsg(_, _, _))
        .WillOnce(SetErrnoAndReturn(EOPNOTSUPP, -1));
    WriteCallback write;
    socket->writeChain(&write, IOBuf::copyBuffer("hey"));
  
    evb.loop();
  
    EXPECT_EQ(STATE_FAILED, write.state);
  }
  
  TEST(AsyncSocketTest, TestTFOFallbackToConnect) {
    TestServer server(true);
  
    // Connect using a AsyncSocket
    EventBase evb;
    auto socket = MockAsyncTFOSocket::UniquePtr(new MockAsyncTFOSocket(&evb));
    socket->enableTFO();
  
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
  
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    EXPECT_CALL(*socket, tfoSendMsg(_, _, _))
        .WillOnce(Invoke([&](int fd, struct msghdr*, int) {
          sockaddr_storage addr;
          auto len = server.getAddress().getAddress(&addr);
          return connect(fd, (const struct sockaddr*)&addr, len);
        }));
    WriteCallback write;
    auto sendBuf = IOBuf::copyBuffer("hey");
    socket->writeChain(&write, sendBuf->clone());
    EXPECT_EQ(STATE_WAITING, write.state);
  
    std::array<uint8_t, 128> buf;
    memset(buf.data(), 'a', buf.size());
  
    std::array<uint8_t, 3> readBuf;
  
    std::thread t([&] {
      std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
      acceptedSocket->write(buf.data(), buf.size());
      acceptedSocket->flush();
      acceptedSocket->readAll(readBuf.data(), readBuf.size());
      acceptedSocket->close();
    });
  
    evb.loop();
  
    t.join();
    EXPECT_EQ(0, memcmp(readBuf.data(), sendBuf->data(), readBuf.size()));
  
    EXPECT_EQ(STATE_SUCCEEDED, ccb.state);
    EXPECT_EQ(STATE_SUCCEEDED, write.state);
  
    EXPECT_EQ(STATE_SUCCEEDED, rcb.state);
    ASSERT_EQ(1, rcb.buffers.size());
    ASSERT_EQ(buf.size(), rcb.buffers[0].length);
    EXPECT_EQ(0, memcmp(rcb.buffers[0].buffer, buf.data(), buf.size()));
  }
  
  TEST(AsyncSocketTest, TestTFOFallbackTimeout) {
    // Try connecting to server that won't respond.
    //
    // This depends somewhat on the network where this test is run.
    // Hopefully this IP will be routable but unresponsive.
    // (Alternatively, we could try listening on a local raw socket, but that
    // normally requires root privileges.)
    auto host = SocketAddressTestHelper::isIPv6Enabled()
        ? SocketAddressTestHelper::kGooglePublicDnsAAddrIPv6
        : SocketAddressTestHelper::isIPv4Enabled()
            ? SocketAddressTestHelper::kGooglePublicDnsAAddrIPv4
            : nullptr;
    SocketAddress addr(host, 65535);
  
    // Connect using a AsyncSocket
    EventBase evb;
    auto socket = MockAsyncTFOSocket::UniquePtr(new MockAsyncTFOSocket(&evb));
    socket->enableTFO();
  
    ConnCallback ccb;
    // Set a very small timeout
    socket->connect(&ccb, addr, 1);
    EXPECT_EQ(STATE_SUCCEEDED, ccb.state);
  
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    EXPECT_CALL(*socket, tfoSendMsg(_, _, _))
        .WillOnce(Invoke([&](int fd, struct msghdr*, int) {
          sockaddr_storage addr2;
          auto len = addr.getAddress(&addr2);
          return connect(fd, (const struct sockaddr*)&addr2, len);
        }));
    WriteCallback write;
    socket->writeChain(&write, IOBuf::copyBuffer("hey"));
  
    evb.loop();
  
    EXPECT_EQ(STATE_FAILED, write.state);
  }
  
  TEST(AsyncSocketTest, TestTFOEagain) {
    TestServer server(true);
  
    // Connect using a AsyncSocket
    EventBase evb;
    auto socket = MockAsyncTFOSocket::UniquePtr(new MockAsyncTFOSocket(&evb));
    socket->enableTFO();
  
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
  
    EXPECT_CALL(*socket, tfoSendMsg(_, _, _))
        .WillOnce(SetErrnoAndReturn(EAGAIN, -1));
    WriteCallback write;
    socket->writeChain(&write, IOBuf::copyBuffer("hey"));
  
    evb.loop();
  
    EXPECT_EQ(STATE_SUCCEEDED, ccb.state);
    EXPECT_EQ(STATE_FAILED, write.state);
  }
  
  // Sending a large amount of data in the first write which will
  // definitely not fit into MSS.
  TEST(AsyncSocketTest, ConnectTFOWithBigData) {
    // Start listening on a local port
    TestServer server(true);
  
    // Connect using a AsyncSocket
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    socket->enableTFO();
    ConnCallback cb;
    socket->connect(&cb, server.getAddress(), 30);
  
    std::array<uint8_t, 128> buf;
    memset(buf.data(), 'a', buf.size());
  
    constexpr size_t len = 10 * 1024;
    auto sendBuf = IOBuf::create(len);
    sendBuf->append(len);
    std::array<uint8_t, len> readBuf;
  
    std::thread t([&] {
      auto acceptedSocket = server.accept();
      acceptedSocket->write(buf.data(), buf.size());
      acceptedSocket->flush();
      acceptedSocket->readAll(readBuf.data(), readBuf.size());
      acceptedSocket->close();
    });
  
    evb.loop();
  
    ASSERT_EQ(cb.state, STATE_SUCCEEDED);
    EXPECT_LE(0, socket->getConnectTime().count());
    EXPECT_EQ(socket->getConnectTimeout(), std::chrono::milliseconds(30));
    EXPECT_TRUE(socket->getTFOAttempted());
  
    // Should trigger the connect
    WriteCallback write;
    ReadCallback rcb;
    socket->writeChain(&write, sendBuf->clone());
    socket->setReadCB(&rcb);
    evb.loop();
  
    t.join();
  
    EXPECT_EQ(STATE_SUCCEEDED, write.state);
    EXPECT_EQ(0, memcmp(readBuf.data(), sendBuf->data(), readBuf.size()));
    EXPECT_EQ(STATE_SUCCEEDED, rcb.state);
    ASSERT_EQ(1, rcb.buffers.size());
    ASSERT_EQ(sizeof(buf), rcb.buffers[0].length);
    EXPECT_EQ(0, memcmp(rcb.buffers[0].buffer, buf.data(), buf.size()));
    EXPECT_EQ(socket->getTFOFinished(), socket->getTFOSucceded());
  }
  
  #endif // FOLLY_ALLOW_TFO
  
  class MockEvbChangeCallback : public AsyncSocket::EvbChangeCallback {
   public:
    MOCK_METHOD1(evbAttached, void(AsyncSocket*));
    MOCK_METHOD1(evbDetached, void(AsyncSocket*));
  };
  
  TEST(AsyncSocketTest, EvbCallbacks) {
    auto cb = std::make_unique<MockEvbChangeCallback>();
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
  
    InSequence seq;
    EXPECT_CALL(*cb, evbDetached(socket.get())).Times(1);
    EXPECT_CALL(*cb, evbAttached(socket.get())).Times(1);
  
    socket->setEvbChangedCallback(std::move(cb));
    socket->detachEventBase();
    socket->attachEventBase(&evb);
  }
  
  TEST(AsyncSocketTest, TestEvbDetachWtRegisteredIOHandlers) {
    // Start listening on a local port
    TestServer server;
  
    // Connect using a AsyncSocket
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    ConnCallback cb;
    socket->connect(&cb, server.getAddress(), 30);
  
    evb.loop();
  
    ASSERT_EQ(cb.state, STATE_SUCCEEDED);
    EXPECT_LE(0, socket->getConnectTime().count());
    EXPECT_EQ(socket->getConnectTimeout(), std::chrono::milliseconds(30));
  
    // After the ioHandlers are registered, still should be able to detach/attach
    ReadCallback rcb;
    socket->setReadCB(&rcb);
  
    auto cbEvbChg = std::make_unique<MockEvbChangeCallback>();
    InSequence seq;
    EXPECT_CALL(*cbEvbChg, evbDetached(socket.get())).Times(1);
    EXPECT_CALL(*cbEvbChg, evbAttached(socket.get())).Times(1);
  
    socket->setEvbChangedCallback(std::move(cbEvbChg));
    EXPECT_TRUE(socket->isDetachable());
    socket->detachEventBase();
    socket->attachEventBase(&evb);
  
    socket->close();
  }
  
  #ifdef FOLLY_HAVE_MSG_ERRQUEUE
  /* copied from include/uapi/linux/net_tstamp.h */
  /* SO_TIMESTAMPING gets an integer bit field comprised of these values */
  enum SOF_TIMESTAMPING {
    SOF_TIMESTAMPING_SOFTWARE = (1 << 4),
    SOF_TIMESTAMPING_OPT_ID = (1 << 7),
    SOF_TIMESTAMPING_TX_SCHED = (1 << 8),
    SOF_TIMESTAMPING_OPT_CMSG = (1 << 10),
    SOF_TIMESTAMPING_OPT_TSONLY = (1 << 11),
  };
  
  class TestErrMessageCallback : public folly::AsyncSocket::ErrMessageCallback {
   public:
    TestErrMessageCallback()
        : exception_(folly::AsyncSocketException::UNKNOWN, "none") {}
  
    void errMessage(const cmsghdr& cmsg) noexcept override {
      if (cmsg.cmsg_level == SOL_SOCKET && cmsg.cmsg_type == SCM_TIMESTAMPING) {
        gotTimestamp_++;
        checkResetCallback();
      } else if (
          (cmsg.cmsg_level == SOL_IP && cmsg.cmsg_type == IP_RECVERR) ||
          (cmsg.cmsg_level == SOL_IPV6 && cmsg.cmsg_type == IPV6_RECVERR)) {
        gotByteSeq_++;
        checkResetCallback();
      }
    }
  
    void errMessageError(
        const folly::AsyncSocketException& ex) noexcept override {
      exception_ = ex;
    }
  
    void checkResetCallback() noexcept {
      if (socket_ != nullptr && resetAfter_ != -1 &&
          gotTimestamp_ + gotByteSeq_ == resetAfter_) {
        socket_->setErrMessageCB(nullptr);
      }
    }
  
    folly::AsyncSocket* socket_{nullptr};
    folly::AsyncSocketException exception_;
    int gotTimestamp_{0};
    int gotByteSeq_{0};
    int resetAfter_{-1};
  };
  
  TEST(AsyncSocketTest, ErrMessageCallback) {
    TestServer server;
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
  
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
    LOG(INFO) << "Client socket fd=" << socket->getFd();
  
    // Let the socket
    evb.loop();
  
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
  
    // Set read callback to keep the socket subscribed for event
    // notifications. Though we're no planning to read anything from
    // this side of the connection.
    ReadCallback rcb(1);
    socket->setReadCB(&rcb);
  
    // Set up timestamp callbacks
    TestErrMessageCallback errMsgCB;
    socket->setErrMessageCB(&errMsgCB);
    ASSERT_EQ(socket->getErrMessageCallback(),
              static_cast<folly::AsyncSocket::ErrMessageCallback*>(&errMsgCB));
  
    errMsgCB.socket_ = socket.get();
    errMsgCB.resetAfter_ = 3;
  
    // Enable timestamp notifications
    ASSERT_GT(socket->getFd(), 0);
    int flags = SOF_TIMESTAMPING_OPT_ID
                | SOF_TIMESTAMPING_OPT_TSONLY
                | SOF_TIMESTAMPING_SOFTWARE
                | SOF_TIMESTAMPING_OPT_CMSG
                | SOF_TIMESTAMPING_TX_SCHED;
    AsyncSocket::OptionKey tstampingOpt = {SOL_SOCKET, SO_TIMESTAMPING};
    EXPECT_EQ(tstampingOpt.apply(socket->getFd(), flags), 0);
  
    // write()
    std::vector<uint8_t> wbuf(128, 'a');
    WriteCallback wcb;
    // Send two packets to get two EOM notifications
    socket->write(&wcb, wbuf.data(), wbuf.size() / 2);
    socket->write(&wcb, wbuf.data() + wbuf.size() / 2, wbuf.size() / 2);
  
    // Accept the connection.
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
    LOG(INFO) << "Server socket fd=" << acceptedSocket->getSocketFD();
  
    // Loop
    evb.loopOnce();
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  
    // Check that we can read the data that was written to the socket
    std::vector<uint8_t> rbuf(1 + wbuf.size(), 0);
    uint32_t bytesRead = acceptedSocket->read(rbuf.data(), rbuf.size());
    ASSERT_TRUE(std::equal(wbuf.begin(), wbuf.end(), rbuf.begin()));
    ASSERT_EQ(bytesRead, wbuf.size());
  
    // Close both sockets
    acceptedSocket->close();
    socket->close();
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  
    // Check for the timestamp notifications.
    ASSERT_EQ(errMsgCB.exception_.type_, folly::AsyncSocketException::UNKNOWN);
    ASSERT_GT(errMsgCB.gotByteSeq_, 0);
    ASSERT_GT(errMsgCB.gotTimestamp_, 0);
    ASSERT_EQ(
        errMsgCB.gotByteSeq_ + errMsgCB.gotTimestamp_, errMsgCB.resetAfter_);
  }
  #endif // FOLLY_HAVE_MSG_ERRQUEUE
  
  TEST(AsyncSocket, PreReceivedData) {
    TestServer server;
  
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    socket->connect(nullptr, server.getAddress(), 30);
    evb.loop();
  
    socket->writeChain(nullptr, IOBuf::copyBuffer("hello"));
  
    auto acceptedSocket = server.acceptAsync(&evb);
  
    ReadCallback peekCallback(2);
    ReadCallback readCallback;
    peekCallback.dataAvailableCallback = [&]() {
      peekCallback.verifyData("he", 2);
      acceptedSocket->setPreReceivedData(IOBuf::copyBuffer("h"));
      acceptedSocket->setPreReceivedData(IOBuf::copyBuffer("e"));
      acceptedSocket->setReadCB(nullptr);
      acceptedSocket->setReadCB(&readCallback);
    };
    readCallback.dataAvailableCallback = [&]() {
      if (readCallback.dataRead() == 5) {
        readCallback.verifyData("hello", 5);
        acceptedSocket->setReadCB(nullptr);
      }
    };
  
    acceptedSocket->setReadCB(&peekCallback);
  
    evb.loop();
  }
  
  TEST(AsyncSocket, PreReceivedDataOnly) {
    TestServer server;
  
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    socket->connect(nullptr, server.getAddress(), 30);
    evb.loop();
  
    socket->writeChain(nullptr, IOBuf::copyBuffer("hello"));
  
    auto acceptedSocket = server.acceptAsync(&evb);
  
    ReadCallback peekCallback;
    ReadCallback readCallback;
    peekCallback.dataAvailableCallback = [&]() {
      peekCallback.verifyData("hello", 5);
      acceptedSocket->setPreReceivedData(IOBuf::copyBuffer("hello"));
      acceptedSocket->setReadCB(&readCallback);
    };
    readCallback.dataAvailableCallback = [&]() {
      readCallback.verifyData("hello", 5);
      acceptedSocket->setReadCB(nullptr);
    };
  
    acceptedSocket->setReadCB(&peekCallback);
  
    evb.loop();
  }
  
  TEST(AsyncSocket, PreReceivedDataPartial) {
    TestServer server;
  
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    socket->connect(nullptr, server.getAddress(), 30);
    evb.loop();
  
    socket->writeChain(nullptr, IOBuf::copyBuffer("hello"));
  
    auto acceptedSocket = server.acceptAsync(&evb);
  
    ReadCallback peekCallback;
    ReadCallback smallReadCallback(3);
    ReadCallback normalReadCallback;
    peekCallback.dataAvailableCallback = [&]() {
      peekCallback.verifyData("hello", 5);
      acceptedSocket->setPreReceivedData(IOBuf::copyBuffer("hello"));
      acceptedSocket->setReadCB(&smallReadCallback);
    };
    smallReadCallback.dataAvailableCallback = [&]() {
      smallReadCallback.verifyData("hel", 3);
      acceptedSocket->setReadCB(&normalReadCallback);
    };
    normalReadCallback.dataAvailableCallback = [&]() {
      normalReadCallback.verifyData("lo", 2);
      acceptedSocket->setReadCB(nullptr);
    };
  
    acceptedSocket->setReadCB(&peekCallback);
  
    evb.loop();
  }
  
  TEST(AsyncSocket, PreReceivedDataTakeover) {
    TestServer server;
  
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
    socket->connect(nullptr, server.getAddress(), 30);
    evb.loop();
  
    socket->writeChain(nullptr, IOBuf::copyBuffer("hello"));
  
    auto acceptedSocket =
        AsyncSocket::UniquePtr(new AsyncSocket(&evb, server.acceptFD()));
    AsyncSocket::UniquePtr takeoverSocket;
  
    ReadCallback peekCallback(3);
    ReadCallback readCallback;
    peekCallback.dataAvailableCallback = [&]() {
      peekCallback.verifyData("hel", 3);
      acceptedSocket->setPreReceivedData(IOBuf::copyBuffer("hello"));
      acceptedSocket->setReadCB(nullptr);
      takeoverSocket =
          AsyncSocket::UniquePtr(new AsyncSocket(std::move(acceptedSocket)));
      takeoverSocket->setReadCB(&readCallback);
    };
    readCallback.dataAvailableCallback = [&]() {
      readCallback.verifyData("hello", 5);
      takeoverSocket->setReadCB(nullptr);
    };
  
    acceptedSocket->setReadCB(&peekCallback);
  
    evb.loop();
  }
  
  #ifdef MSG_NOSIGNAL
  TEST(AsyncSocketTest, SendMessageFlags) {
    TestServer server;
    TestSendMsgParamsCallback sendMsgCB(
        MSG_DONTWAIT|MSG_NOSIGNAL|MSG_MORE, 0, nullptr);
  
    // connect()
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb);
  
    ConnCallback ccb;
    socket->connect(&ccb, server.getAddress(), 30);
    std::shared_ptr<BlockingSocket> acceptedSocket = server.accept();
  
    evb.loop();
    ASSERT_EQ(ccb.state, STATE_SUCCEEDED);
  
    // Set SendMsgParamsCallback
    socket->setSendMsgParamCB(&sendMsgCB);
    ASSERT_EQ(socket->getSendMsgParamsCB(), &sendMsgCB);
  
    // Write the first portion of data. This data is expected to be
    // sent out immediately.
    std::vector<uint8_t> buf(128, 'a');
    WriteCallback wcb;
    sendMsgCB.reset(MSG_DONTWAIT | MSG_NOSIGNAL);
    socket->write(&wcb, buf.data(), buf.size());
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
    ASSERT_TRUE(sendMsgCB.queriedFlags_);
    ASSERT_FALSE(sendMsgCB.queriedData_);
  
    // Using different flags for the second write operation.
    // MSG_MORE flag is expected to delay sending this
    // data to the wire.
    sendMsgCB.reset(MSG_DONTWAIT | MSG_NOSIGNAL | MSG_MORE);
    socket->write(&wcb, buf.data(), buf.size());
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
    ASSERT_TRUE(sendMsgCB.queriedFlags_);
    ASSERT_FALSE(sendMsgCB.queriedData_);
  
    // Make sure the accepted socket saw only the data from
    // the first write request.
    std::vector<uint8_t> readbuf(2 * buf.size());
    uint32_t bytesRead = acceptedSocket->read(readbuf.data(), readbuf.size());
    ASSERT_TRUE(std::equal(buf.begin(), buf.end(), readbuf.begin()));
    ASSERT_EQ(bytesRead, buf.size());
  
    // Make sure the server got a connection and received the data
    acceptedSocket->close();
    socket->close();
  
    ASSERT_TRUE(socket->isClosedBySelf());
    ASSERT_FALSE(socket->isClosedByPeer());
  }
  
  TEST(AsyncSocketTest, SendMessageAncillaryData) {
    int fds[2];
    EXPECT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, fds), 0);
  
    // "Client" socket
    int cfd = fds[0];
    ASSERT_NE(cfd, -1);
  
    // "Server" socket
    int sfd = fds[1];
    ASSERT_NE(sfd, -1);
    SCOPE_EXIT { close(sfd); };
  
    // Instantiate AsyncSocket object for the connected socket
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb, cfd);
  
    // Open a temporary file and write a magic string to it
    // We'll transfer the file handle to test the message parameters
    // callback logic.
    TemporaryFile file(StringPiece(),
                       fs::path(),
                       TemporaryFile::Scope::UNLINK_IMMEDIATELY);
    int tmpfd = file.fd();
    ASSERT_NE(tmpfd, -1) << "Failed to open a temporary file";
    std::string magicString("Magic string");
    ASSERT_EQ(write(tmpfd, magicString.c_str(), magicString.length()),
              magicString.length());
  
    // Send message
    union {
      // Space large enough to hold an 'int'
      char control[CMSG_SPACE(sizeof(int))];
      struct cmsghdr cmh;
    } s_u;
    s_u.cmh.cmsg_len = CMSG_LEN(sizeof(int));
    s_u.cmh.cmsg_level = SOL_SOCKET;
    s_u.cmh.cmsg_type = SCM_RIGHTS;
    memcpy(CMSG_DATA(&s_u.cmh), &tmpfd, sizeof(int));
  
    // Set up the callback providing message parameters
    TestSendMsgParamsCallback sendMsgCB(
        MSG_DONTWAIT | MSG_NOSIGNAL, sizeof(s_u.control), s_u.control);
    socket->setSendMsgParamCB(&sendMsgCB);
  
    // We must transmit at least 1 byte of real data in order
    // to send ancillary data
    int s_data = 12345;
    WriteCallback wcb;
    socket->write(&wcb, &s_data, sizeof(s_data));
    ASSERT_EQ(wcb.state, STATE_SUCCEEDED);
  
    // Receive the message
    union {
      // Space large enough to hold an 'int'
      char control[CMSG_SPACE(sizeof(int))];
      struct cmsghdr cmh;
    } r_u;
    struct msghdr msgh;
    struct iovec iov;
    int r_data = 0;
  
    msgh.msg_control = r_u.control;
    msgh.msg_controllen = sizeof(r_u.control);
    msgh.msg_name = nullptr;
    msgh.msg_namelen = 0;
    msgh.msg_iov = &iov;
    msgh.msg_iovlen = 1;
    iov.iov_base = &r_data;
    iov.iov_len = sizeof(r_data);
  
    // Receive data
    ASSERT_NE(recvmsg(sfd, &msgh, 0), -1) << "recvmsg failed: " << errno;
  
    // Validate the received message
    ASSERT_EQ(r_u.cmh.cmsg_len, CMSG_LEN(sizeof(int)));
    ASSERT_EQ(r_u.cmh.cmsg_level, SOL_SOCKET);
    ASSERT_EQ(r_u.cmh.cmsg_type, SCM_RIGHTS);
    ASSERT_EQ(r_data, s_data);
    int fd = 0;
    memcpy(&fd, CMSG_DATA(&r_u.cmh), sizeof(int));
    ASSERT_NE(fd, 0);
    SCOPE_EXIT { close(fd); };
  
    std::vector<uint8_t> transferredMagicString(magicString.length() + 1, 0);
  
    // Reposition to the beginning of the file
    ASSERT_EQ(0, lseek(fd, 0, SEEK_SET));
  
    // Read the magic string back, and compare it with the original
    ASSERT_EQ(
        magicString.length(),
        read(fd, transferredMagicString.data(), transferredMagicString.size()));
    ASSERT_TRUE(std::equal(
        magicString.begin(),
        magicString.end(),
        transferredMagicString.begin()));
  }
  
  TEST(AsyncSocketTest, UnixDomainSocketErrMessageCB) {
    // In the latest stable kernel 4.14.3 as of 2017-12-04, Unix Domain
    // Socket (UDS) does not support MSG_ERRQUEUE. So
    // recvmsg(MSG_ERRQUEUE) will read application data from UDS which
    // breaks application message flow.  To avoid this problem,
    // AsyncSocket currently disables setErrMessageCB for UDS.
    //
    // This tests two things for UDS
    // 1. setErrMessageCB fails
    // 2. recvmsg(MSG_ERRQUEUE) reads application data
    //
    // Feel free to remove this test if UDS supports MSG_ERRQUEUE in the future.
  
    int fd[2];
    EXPECT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, fd), 0);
    ASSERT_NE(fd[0], -1);
    ASSERT_NE(fd[1], -1);
    SCOPE_EXIT {
      close(fd[1]);
    };
  
    EXPECT_EQ(fcntl(fd[0], F_SETFL, O_NONBLOCK), 0);
    EXPECT_EQ(fcntl(fd[1], F_SETFL, O_NONBLOCK), 0);
  
    EventBase evb;
    std::shared_ptr<AsyncSocket> socket = AsyncSocket::newSocket(&evb, fd[0]);
  
    // setErrMessageCB should fail for unix domain socket
    TestErrMessageCallback errMsgCB;
    ASSERT_NE(&errMsgCB, nullptr);
    socket->setErrMessageCB(&errMsgCB);
    ASSERT_EQ(socket->getErrMessageCallback(), nullptr);
  
  #ifdef FOLLY_HAVE_MSG_ERRQUEUE
    // The following verifies that MSG_ERRQUEUE does not work for UDS,
    // and recvmsg reads application data
    union {
      // Space large enough to hold an 'int'
      char control[CMSG_SPACE(sizeof(int))];
      struct cmsghdr cmh;
    } r_u;
    struct msghdr msgh;
    struct iovec iov;
    int recv_data = 0;
  
    msgh.msg_control = r_u.control;
    msgh.msg_controllen = sizeof(r_u.control);
    msgh.msg_name = nullptr;
    msgh.msg_namelen = 0;
    msgh.msg_iov = &iov;
    msgh.msg_iovlen = 1;
    iov.iov_base = &recv_data;
    iov.iov_len = sizeof(recv_data);
  
    // there is no data, recvmsg should fail
    EXPECT_EQ(recvmsg(fd[1], &msgh, MSG_ERRQUEUE), -1);
    EXPECT_TRUE(errno == EAGAIN || errno == EWOULDBLOCK);
  
    // provide some application data, error queue should be empty if it exists
    // However, UDS reads application data as error message
    int test_data = 123456;
    WriteCallback wcb;
    socket->write(&wcb, &test_data, sizeof(test_data));
    recv_data = 0;
    ASSERT_NE(recvmsg(fd[1], &msgh, MSG_ERRQUEUE), -1);
    ASSERT_EQ(recv_data, test_data);
  #endif // FOLLY_HAVE_MSG_ERRQUEUE
  }
  #endif
  