C++ EventBase::runInLoop方法代码示例

/**
 * Test that EventBase::loop() correctly detects when there are no more events
 * left to run.
 *
 * This uses a single callback, which alternates registering itself as a loop
 * callback versus a EventHandler callback.  This exercises a regression where
 * EventBase::loop() incorrectly exited if there were no more fd handlers
 * registered, but a loop callback installed a new fd handler.
 */
TEST(EventBaseTest, LoopTermination) {
  EventBase eventBase;

  // Open a pipe and close the write end,
  // so the read endpoint will be readable
  int pipeFds[2];
  int rc = pipe(pipeFds);
  ASSERT_EQ(rc, 0);
  close(pipeFds[1]);
  TerminateTestCallback callback(&eventBase, pipeFds[0]);

  // Test once where the callback will exit after a loop callback
  callback.reset(10, 100);
  eventBase.runInLoop(&callback);
  eventBase.loop();
  ASSERT_EQ(callback.getLoopInvocations(), 10);
  ASSERT_EQ(callback.getEventInvocations(), 9);

  // Test once where the callback will exit after an fd event callback
  callback.reset(100, 7);
  eventBase.runInLoop(&callback);
  eventBase.loop();
  ASSERT_EQ(callback.getLoopInvocations(), 7);
  ASSERT_EQ(callback.getEventInvocations(), 7);

  close(pipeFds[0]);
}

// Test cancelling runInLoop() callbacks
TEST(EventBaseTest, CancelRunInLoop) {
  EventBase eventBase;

  CountedLoopCallback c1(&eventBase, 20);
  CountedLoopCallback c2(&eventBase, 20);
  CountedLoopCallback c3(&eventBase, 20);

  std::function<void()> cancelC1Action =
    std::bind(&EventBase::LoopCallback::cancelLoopCallback, &c1);
  std::function<void()> cancelC2Action =
    std::bind(&EventBase::LoopCallback::cancelLoopCallback, &c2);

  CountedLoopCallback cancelC1(&eventBase, 10, cancelC1Action);
  CountedLoopCallback cancelC2(&eventBase, 10, cancelC2Action);

  // Install cancelC1 after c1
  eventBase.runInLoop(&c1);
  eventBase.runInLoop(&cancelC1);

  // Install cancelC2 before c2
  eventBase.runInLoop(&cancelC2);
  eventBase.runInLoop(&c2);

  // Install c3
  eventBase.runInLoop(&c3);

  ASSERT_EQ(c1.getCount(), 20);
  ASSERT_EQ(c2.getCount(), 20);
  ASSERT_EQ(c3.getCount(), 20);
  ASSERT_EQ(cancelC1.getCount(), 10);
  ASSERT_EQ(cancelC2.getCount(), 10);

  // Run the loop
  eventBase.loop();

  // cancelC1 and cancelC3 should have both fired after 10 iterations and
  // stopped re-installing themselves
  ASSERT_EQ(cancelC1.getCount(), 0);
  ASSERT_EQ(cancelC2.getCount(), 0);
  // c3 should have continued on for the full 20 iterations
  ASSERT_EQ(c3.getCount(), 0);

  // c1 and c2 should have both been cancelled on the 10th iteration.
  //
  // Callbacks are always run in the order they are installed,
  // so c1 should have fired 10 times, and been canceled after it ran on the
  // 10th iteration.  c2 should have only fired 9 times, because cancelC2 will
  // have run before it on the 10th iteration, and cancelled it before it
  // fired.
  ASSERT_EQ(c1.getCount(), 10);
  ASSERT_EQ(c2.getCount(), 11);
}

BENCHMARK(timeMeasurementsOn, n) {
  EventBase eventBase;

  while (n--) {
    CountedLoopCallback c(&eventBase, 10);
    eventBase.runInLoop(&c);
    eventBase.loop();
  }
}

// Test that EventBase::loop() doesn't exit while there are
// still LoopCallbacks remaining to be invoked.
TEST(EventBaseTest, RepeatedRunInLoop) {
  EventBase eventBase;

  CountedLoopCallback c(&eventBase, 10);
  eventBase.runInLoop(&c);
  // The callback shouldn't have run immediately
  ASSERT_EQ(c.getCount(), 10);
  eventBase.loop();

  // loop() should loop until the CountedLoopCallback stops
  // re-installing itself.
  ASSERT_EQ(c.getCount(), 0);
}

void QueueTest::maxReadAtOnce() {
  // Add 100 messages to the queue
  for (int n = 0; n < 100; ++n) {
    queue.putMessage(n);
  }

  EventBase eventBase;

  // Record how many messages were processed each loop iteration.
  uint32_t messagesThisLoop = 0;
  std::vector<uint32_t> messagesPerLoop;
  std::function<void()> loopFinished = [&] {
    // Record the current number of messages read this loop
    messagesPerLoop.push_back(messagesThisLoop);
    // Reset messagesThisLoop to 0 for the next loop
    messagesThisLoop = 0;

    // To prevent use-after-free bugs when eventBase destructs,
    // prevent calling runInLoop any more after the test is finished.
    // 55 == number of times loop should run.
    if (messagesPerLoop.size() != 55) {
      // Reschedule ourself to run at the end of the next loop
      eventBase.runInLoop(loopFinished);
    }
  };
  // Schedule the first call to loopFinished
  eventBase.runInLoop(loopFinished);

  QueueConsumer consumer;
  // Read the first 50 messages 10 at a time.
  consumer.setMaxReadAtOnce(10);
  consumer.fn = [&](int value) {
    ++messagesThisLoop;
    // After 50 messages, drop to reading only 1 message at a time.
    if (value == 50) {
      consumer.setMaxReadAtOnce(1);
    }
    // Terminate the loop when we reach the end of the messages.
    if (value == 99) {
      eventBase.terminateLoopSoon();
    }
  };
  consumer.startConsuming(&eventBase, &queue);

  // Run the event loop until the consumer terminates it
  eventBase.loop();

  // The consumer should have read all 100 messages in order
  EXPECT_EQ(100, consumer.messages.size());
  for (int n = 0; n < 100; ++n) {
    EXPECT_EQ(n, consumer.messages.at(n));
  }

  // Currently EventBase happens to still run the loop callbacks even after
  // terminateLoopSoon() is called.  However, we don't really want to depend on
  // this behavior.  In case this ever changes in the future, add
  // messagesThisLoop to messagesPerLoop in loop callback isn't invoked for the
  // last loop iteration.
  if (messagesThisLoop > 0) {
    messagesPerLoop.push_back(messagesThisLoop);
    messagesThisLoop = 0;
  }

  // For the first 5 loops it should have read 10 messages each time.
  // After that it should have read 1 messages per loop for the next 50 loops.
  EXPECT_EQ(55, messagesPerLoop.size());
  for (int n = 0; n < 5; ++n) {
    EXPECT_EQ(10, messagesPerLoop.at(n));
  }
  for (int n = 5; n < 55; ++n) {
    EXPECT_EQ(1, messagesPerLoop.at(n));
  }
}