text: /*
   * Copyright 2015 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 <gtest/gtest.h>
  
  #include <folly/futures/Future.h>
  #include <folly/io/async/EventBase.h>
  #include <folly/Baton.h>
  
  using namespace folly;
  using std::vector;
  using std::chrono::milliseconds;
  
  TEST(Wait, waitImmediate) {
    makeFuture().wait();
    auto done = makeFuture(42).wait().value();
    EXPECT_EQ(42, done);
  
    vector<int> v{1,2,3};
    auto done_v = makeFuture(v).wait().value();
    EXPECT_EQ(v.size(), done_v.size());
    EXPECT_EQ(v, done_v);
  
    vector<Future<void>> v_f;
    v_f.push_back(makeFuture());
    v_f.push_back(makeFuture());
    auto done_v_f = collectAll(v_f).wait().value();
    EXPECT_EQ(2, done_v_f.size());
  
    vector<Future<bool>> v_fb;
    v_fb.push_back(makeFuture(true));
    v_fb.push_back(makeFuture(false));
    auto fut = collectAll(v_fb);
    auto done_v_fb = std::move(fut.wait().value());
    EXPECT_EQ(2, done_v_fb.size());
  }
  
  TEST(Wait, wait) {
    Promise<int> p;
    Future<int> f = p.getFuture();
    std::atomic<bool> flag{false};
    std::atomic<int> result{1};
    std::atomic<std::thread::id> id;
  
    std::thread t([&](Future<int>&& tf){
        auto n = tf.then([&](Try<int> && t) {
            id = std::this_thread::get_id();
            return t.value();
          });
        flag = true;
        result.store(n.wait().value());
      },
      std::move(f)
      );
    while(!flag){}
    EXPECT_EQ(result.load(), 1);
    p.setValue(42);
    t.join();
    // validate that the callback ended up executing in this thread, which
    // is more to ensure that this test actually tests what it should
    EXPECT_EQ(id, std::this_thread::get_id());
    EXPECT_EQ(result.load(), 42);
  }
  
  struct MoveFlag {
    MoveFlag() = default;
    MoveFlag& operator=(const MoveFlag&) = delete;
    MoveFlag(const MoveFlag&) = delete;
    MoveFlag(MoveFlag&& other) noexcept {
      other.moved = true;
    }
    bool moved{false};
  };
  
  TEST(Wait, waitReplacesSelf) {
    // wait
    {
      // lvalue
      auto f1 = makeFuture(MoveFlag());
      f1.wait();
      EXPECT_FALSE(f1.value().moved);
  
      // rvalue
      auto f2 = makeFuture(MoveFlag()).wait();
      EXPECT_FALSE(f2.value().moved);
    }
  
    // wait(Duration)
    {
      // lvalue
      auto f1 = makeFuture(MoveFlag());
      f1.wait(milliseconds(1));
      EXPECT_FALSE(f1.value().moved);
  
      // rvalue
      auto f2 = makeFuture(MoveFlag()).wait(milliseconds(1));
      EXPECT_FALSE(f2.value().moved);
    }
  
    // waitVia
    {
      folly::EventBase eb;
      // lvalue
      auto f1 = makeFuture(MoveFlag());
      f1.waitVia(&eb);
      EXPECT_FALSE(f1.value().moved);
  
      // rvalue
      auto f2 = makeFuture(MoveFlag()).waitVia(&eb);
      EXPECT_FALSE(f2.value().moved);
    }
  }
  
  TEST(Wait, waitWithDuration) {
   {
    Promise<int> p;
    Future<int> f = p.getFuture();
    f.wait(milliseconds(1));
    EXPECT_FALSE(f.isReady());
    p.setValue(1);
    EXPECT_TRUE(f.isReady());
   }
   {
    Promise<int> p;
    Future<int> f = p.getFuture();
    p.setValue(1);
    f.wait(milliseconds(1));
    EXPECT_TRUE(f.isReady());
   }
   {
    vector<Future<bool>> v_fb;
    v_fb.push_back(makeFuture(true));
    v_fb.push_back(makeFuture(false));
    auto f = collectAll(v_fb);
    f.wait(milliseconds(1));
    EXPECT_TRUE(f.isReady());
    EXPECT_EQ(2, f.value().size());
   }
   {
    vector<Future<bool>> v_fb;
    Promise<bool> p1;
    Promise<bool> p2;
    v_fb.push_back(p1.getFuture());
    v_fb.push_back(p2.getFuture());
    auto f = collectAll(v_fb);
    f.wait(milliseconds(1));
    EXPECT_FALSE(f.isReady());
    p1.setValue(true);
    EXPECT_FALSE(f.isReady());
    p2.setValue(true);
    EXPECT_TRUE(f.isReady());
   }
   {
    auto f = makeFuture().wait(milliseconds(1));
    EXPECT_TRUE(f.isReady());
   }
  
   {
     Promise<void> p;
     auto start = std::chrono::steady_clock::now();
     auto f = p.getFuture().wait(milliseconds(100));
     auto elapsed = std::chrono::steady_clock::now() - start;
     EXPECT_GE(elapsed, milliseconds(100));
     EXPECT_FALSE(f.isReady());
     p.setValue();
     EXPECT_TRUE(f.isReady());
   }
  
   {
     // Try to trigger the race where the resultant Future is not yet complete
     // even if we didn't hit the timeout, and make sure we deal with it properly
     Promise<void> p;
     folly::Baton<> b;
     auto t = std::thread([&]{
       b.post();
       /* sleep override */ std::this_thread::sleep_for(milliseconds(100));
       p.setValue();
     });
     b.wait();
     auto f = p.getFuture().wait(std::chrono::seconds(3600));
     EXPECT_TRUE(f.isReady());
     t.join();
   }
  }
  