text: /*
   *
   * Copyright 2017 gRPC authors.
   *
   * 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 <atomic>
  #include <memory>
  #include <mutex>
  #include <random>
  #include <sstream>
  #include <thread>
  
  #include <gmock/gmock.h>
  
  #include <grpc/grpc.h>
  #include <grpc/support/alloc.h>
  #include <grpc/support/log.h>
  #include <grpc/support/string_util.h>
  #include <grpc/support/time.h>
  #include <grpcpp/channel.h>
  #include <grpcpp/client_context.h>
  #include <grpcpp/create_channel.h>
  #include <grpcpp/impl/codegen/sync.h>
  #include <grpcpp/server.h>
  #include <grpcpp/server_builder.h>
  
  #include "src/core/ext/filters/client_channel/lb_policy/grpclb/grpclb_balancer_addresses.h"
  #include "src/core/ext/filters/client_channel/parse_address.h"
  #include "src/core/ext/filters/client_channel/resolver/fake/fake_resolver.h"
  #include "src/core/ext/filters/client_channel/server_address.h"
  #include "src/core/lib/gprpp/ref_counted_ptr.h"
  #include "src/core/lib/gprpp/thd.h"
  #include "src/core/lib/iomgr/sockaddr.h"
  
  #include "test/core/util/port.h"
  #include "test/core/util/test_config.h"
  
  namespace {
  
  void TryConnectAndDestroy() {
    auto response_generator =
        grpc_core::MakeRefCounted<grpc_core::FakeResolverResponseGenerator>();
    // Return a grpclb address with an IP address on the IPv6 discard prefix
    // (https://tools.ietf.org/html/rfc6666). This is important because
    // the behavior we want in this test is for a TCP connect attempt to "hang",
    // i.e. we want to send SYN, and then *not* receive SYN-ACK or RST.
    // The precise behavior is dependant on the test runtime environment though,
    // since connect() attempts on this address may unfortunately result in
    // "network unreachable" errors in some test runtime environments.
    const char* uri_str = "ipv6:[0100::1234]:443";
    grpc_uri* lb_uri = grpc_uri_parse(uri_str, true);
    ASSERT_NE(lb_uri, nullptr);
    grpc_resolved_address address;
    ASSERT_TRUE(grpc_parse_uri(lb_uri, &address));
    grpc_uri_destroy(lb_uri);
    grpc_core::ServerAddressList addresses;
    addresses.emplace_back(address.addr, address.len, nullptr);
    grpc_core::Resolver::Result lb_address_result;
    grpc_error* error = GRPC_ERROR_NONE;
    lb_address_result.service_config = grpc_core::ServiceConfig::Create(
        "{\"loadBalancingConfig\":[{\"grpclb\":{}}]}", &error);
    ASSERT_EQ(error, GRPC_ERROR_NONE) << grpc_error_string(error);
    grpc_arg arg = grpc_core::CreateGrpclbBalancerAddressesArg(&addresses);
    lb_address_result.args = grpc_channel_args_copy_and_add(nullptr, &arg, 1);
    response_generator->SetResponse(lb_address_result);
    grpc::ChannelArguments args;
    args.SetPointer(GRPC_ARG_FAKE_RESOLVER_RESPONSE_GENERATOR,
                    response_generator.get());
    // Explicitly set the connect deadline to the same amount of
    // time as the WaitForConnected time. The goal is to get the
    // connect timeout code to run at about the same time as when
    // the channel gets destroyed, to try to reproduce a race.
    args.SetInt("grpc.testing.fixed_reconnect_backoff_ms",
                grpc_test_slowdown_factor() * 100);
    std::ostringstream uri;
    uri << "fake:///servername_not_used";
    auto channel = ::grpc::CreateCustomChannel(
        uri.str(), grpc::InsecureChannelCredentials(), args);
    // Start connecting, and give some time for the TCP connection attempt to the
    // unreachable balancer to begin. The connection should never become ready
    // because the LB we're trying to connect to is unreachable.
    channel->GetState(true /* try_to_connect */);
    ASSERT_FALSE(
        channel->WaitForConnected(grpc_timeout_milliseconds_to_deadline(100)));
    ASSERT_EQ("grpclb", channel->GetLoadBalancingPolicyName());
    channel.reset();
  };
  
  TEST(DestroyGrpclbChannelWithActiveConnectStressTest,
       LoopTryConnectAndDestroy) {
    grpc_init();
    std::vector<std::unique_ptr<std::thread>> threads;
    // 100 is picked for number of threads just
    // because it's enough to reproduce a certain crash almost 100%
    // at this time of writing.
    const int kNumThreads = 100;
    threads.reserve(kNumThreads);
    for (int i = 0; i < kNumThreads; i++) {
      threads.emplace_back(new std::thread(TryConnectAndDestroy));
    }
    for (int i = 0; i < threads.size(); i++) {
      threads[i]->join();
    }
    grpc_shutdown();
  }
  
  }  // namespace
  
  int main(int argc, char** argv) {
    grpc::testing::TestEnvironment env(argc, argv);
    ::testing::InitGoogleTest(&argc, argv);
    auto result = RUN_ALL_TESTS();
    return result;
  }
  