text: /*
   * Copyright 2017 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/Baton.h>
  #include <folly/futures/Future.h>
  #include <folly/futures/InlineExecutor.h>
  #include <folly/futures/ManualExecutor.h>
  #include <folly/futures/QueuedImmediateExecutor.h>
  #include <folly/portability/GTest.h>
  
  using namespace folly;
  
  TEST(ManualExecutor, runIsStable) {
    ManualExecutor x;
    size_t count = 0;
    auto f1 = [&]() { count++; };
    auto f2 = [&]() { x.add(f1); x.add(f1); };
    x.add(f2);
    x.run();
  }
  
  TEST(ManualExecutor, scheduleDur) {
    ManualExecutor x;
    size_t count = 0;
    std::chrono::milliseconds dur {10};
    x.schedule([&]{ count++; }, dur);
    EXPECT_EQ(count, 0);
    x.run();
    EXPECT_EQ(count, 0);
    x.advance(dur/2);
    EXPECT_EQ(count, 0);
    x.advance(dur/2);
    EXPECT_EQ(count, 1);
  }
  
  TEST(ManualExecutor, laterThingsDontBlockEarlierOnes) {
    ManualExecutor x;
    auto first = false;
    std::chrono::milliseconds dur{10};
    x.schedule([&] { first = true; }, dur);
    x.schedule([] {}, 2 * dur);
    EXPECT_FALSE(first);
    x.advance(dur);
    EXPECT_TRUE(first);
  }
  
  TEST(ManualExecutor, orderWillNotBeQuestioned) {
    ManualExecutor x;
    auto first = false;
    auto second = false;
    std::chrono::milliseconds dur{10};
    x.schedule([&] { first = true; }, dur);
    x.schedule([&] { second = true; }, 2 * dur);
    EXPECT_FALSE(first);
    EXPECT_FALSE(second);
    x.advance(dur);
    EXPECT_TRUE(first);
    EXPECT_FALSE(second);
    x.advance(dur);
    EXPECT_TRUE(first);
    EXPECT_TRUE(second);
  }
  
  TEST(ManualExecutor, evenWhenYouSkipAheadEventsRunInProperOrder) {
    ManualExecutor x;
    auto counter = 0;
    auto first = 0;
    auto second = 0;
    std::chrono::milliseconds dur{10};
    x.schedule([&] { first = ++counter; }, dur);
    x.schedule([&] { second = ++counter; }, 2 * dur);
    EXPECT_EQ(first, 0);
    EXPECT_EQ(second, 0);
    x.advance(3 * dur);
    EXPECT_EQ(first, 1);
    EXPECT_EQ(second, 2);
  }
  
  TEST(ManualExecutor, clockStartsAt0) {
    ManualExecutor x;
    EXPECT_EQ(x.now(), x.now().min());
  }
  
  TEST(ManualExecutor, scheduleAbs) {
    ManualExecutor x;
    size_t count = 0;
    x.scheduleAt([&]{ count++; }, x.now() + std::chrono::milliseconds(10));
    EXPECT_EQ(count, 0);
    x.advance(std::chrono::milliseconds(10));
    EXPECT_EQ(count, 1);
  }
  
  TEST(ManualExecutor, advanceTo) {
    ManualExecutor x;
    size_t count = 0;
    x.scheduleAt([&]{ count++; }, std::chrono::steady_clock::now());
    EXPECT_EQ(count, 0);
    x.advanceTo(std::chrono::steady_clock::now());
    EXPECT_EQ(count, 1);
  }
  
  TEST(ManualExecutor, advanceBack) {
    ManualExecutor x;
    size_t count = 0;
    x.advance(std::chrono::microseconds(5));
    x.schedule([&]{ count++; }, std::chrono::microseconds(6));
    EXPECT_EQ(count, 0);
    x.advanceTo(x.now() - std::chrono::microseconds(1));
    EXPECT_EQ(count, 0);
  }
  
  TEST(ManualExecutor, advanceNeg) {
    ManualExecutor x;
    size_t count = 0;
    x.advance(std::chrono::microseconds(5));
    x.schedule([&]{ count++; }, std::chrono::microseconds(6));
    EXPECT_EQ(count, 0);
    x.advance(std::chrono::microseconds(-1));
    EXPECT_EQ(count, 0);
  }
  
  TEST(ManualExecutor, waitForDoesNotDeadlock) {
    ManualExecutor east, west;
    folly::Baton<> baton;
    auto f = makeFuture()
      .via(&east)
      .then([](Try<Unit>){ return makeFuture(); })
      .via(&west);
    std::thread t([&]{
      baton.post();
      west.waitFor(f);
    });
    baton.wait();
    east.run();
    t.join();
  }
  
  TEST(ManualExecutor, getViaDoesNotDeadlock) {
    ManualExecutor east, west;
    folly::Baton<> baton;
    auto f = makeFuture().via(&east).then([](Try<Unit>) {
      return makeFuture();
    }).via(&west);
    std::thread t([&] {
      baton.post();
      f.getVia(&west);
    });
    baton.wait();
    east.run();
    t.join();
  }
  
  TEST(ManualExecutor, clear) {
    ManualExecutor x;
    size_t count = 0;
    x.add([&] { ++count; });
    x.scheduleAt([&] { ++count; }, x.now() + std::chrono::milliseconds(10));
    EXPECT_EQ(0, count);
  
    x.clear();
    x.advance(std::chrono::milliseconds(10));
    x.run();
    EXPECT_EQ(0, count);
  }
  
  TEST(Executor, InlineExecutor) {
    InlineExecutor x;
    size_t counter = 0;
    x.add([&]{
      x.add([&]{
        EXPECT_EQ(counter, 0);
        counter++;
      });
      EXPECT_EQ(counter, 1);
      counter++;
    });
    EXPECT_EQ(counter, 2);
  }
  
  TEST(Executor, QueuedImmediateExecutor) {
    QueuedImmediateExecutor x;
    size_t counter = 0;
    x.add([&]{
      x.add([&]{
        EXPECT_EQ(1, counter);
        counter++;
      });
      EXPECT_EQ(0, counter);
      counter++;
    });
    EXPECT_EQ(2, counter);
  }
  
  TEST(Executor, Runnable) {
    InlineExecutor x;
    size_t counter = 0;
    struct Runnable {
      std::function<void()> fn;
      void operator()() { fn(); }
    };
    Runnable f;
    f.fn = [&]{ counter++; };
    x.add(f);
    EXPECT_EQ(counter, 1);
  }
  
  TEST(Executor, RunnablePtr) {
    InlineExecutor x;
    struct Runnable {
      std::function<void()> fn;
      void operator()() { fn(); }
    };
    size_t counter = 0;
    auto fnp = std::make_shared<Runnable>();
    fnp->fn = [&]{ counter++; };
    x.addPtr(fnp);
    EXPECT_EQ(counter, 1);
  }
  
  TEST(Executor, ThrowableThen) {
    InlineExecutor x;
    auto f = Future<Unit>().via(&x).then([](){
      throw std::runtime_error("Faildog");
    });
    EXPECT_THROW(f.value(), std::exception);
  }
  
  class CrappyExecutor : public Executor {
   public:
    void add(Func /* f */) override { throw std::runtime_error("bad"); }
  };
  
  TEST(Executor, CrappyExecutor) {
    CrappyExecutor x;
    bool flag = false;
    auto f = folly::via(&x).onError([&](std::runtime_error& e) {
      EXPECT_STREQ("bad", e.what());
      flag = true;
    });
    EXPECT_TRUE(flag);
  }
  
  class DoNothingExecutor : public Executor {
   public:
    void add(Func f) override {
      storedFunc_ = std::move(f);
    }
  
   private:
    Func storedFunc_;
  };
  
  TEST(Executor, DoNothingExecutor) {
    DoNothingExecutor x;
  
    // Submit future callback to DoNothingExecutor
    auto f = folly::via(&x).then([] { return 42; });
  
    // Callback function is stored in DoNothingExecutor, but not executed.
    EXPECT_FALSE(f.isReady());
  
    // Destroy the function stored in DoNothingExecutor. The future callback
    // will never get executed.
    x.add({});
  
    EXPECT_TRUE(f.isReady());
    EXPECT_THROW(f.get(), folly::BrokenPromise);
  }
  