base/timer_unittest.cc

// Copyright 2008, Google Inc.
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#include "base/message_loop.h"
#include "base/task.h"
#include "base/timer.h"
#include "testing/gtest/include/gtest/gtest.h"

namespace {
  class TimerTest : public testing::Test {
  };
};

// A base class timer task that sanity-checks timer functionality and counts
// the number of times it has run.  Handles all message loop and memory
// management issues.
class TimerTask : public Task {
 public:
  // Runs all timers to completion.  This returns only after all timers have
  // finished firing.
  static void RunTimers();

  // Creates a new timer.  If |repeating| is true, the timer will repeat 10
  // times before terminating.
  //
  // All timers are managed on the message loop of the thread that calls this
  // function the first time.
  TimerTask(int delay, bool repeating);

  virtual ~TimerTask();

  int iterations() const { return iterations_; }
  const Timer* timer() const { return timer_; }

  // Resets the timer, if it exists.
  void Reset();

  // Task
  virtual void Run();

 protected:
  // Shuts down the message loop if necessary.
  static void QuitMessageLoop();

 private:
  static MessageLoop* message_loop() {
    static MessageLoop* loop = MessageLoop::current();
    return loop;
  }

  static int timer_count_;
  static bool loop_running_;

  bool timer_running_;
  int delay_;
  TimeTicks start_ticks_;
  int iterations_;
  Timer* timer_;
};

// static
void TimerTask::RunTimers() {
  if (timer_count_ && !loop_running_) {
    loop_running_ = true;
    message_loop()->Run();
  }
}

TimerTask::TimerTask(int delay, bool repeating)
    : timer_running_(false),
      delay_(delay),
      start_ticks_(TimeTicks::Now()),
      iterations_(0),
      timer_(NULL) {
  Reset();  // This will just set up the variables to indicate we have a
            // running timer.
  timer_ = message_loop()->timer_manager()->StartTimer(delay, this, repeating);
}

TimerTask::~TimerTask() {
  if (timer_) {
    message_loop()->timer_manager()->StopTimer(timer_);
    delete timer_;
  }
  if (timer_running_) {
    timer_running_ = false;
    if (--timer_count_ <= 0)
      QuitMessageLoop();
  }
}

void TimerTask::Reset() {
  if (!timer_running_) {
    timer_running_ = true;
    ++timer_count_;
  }
  if (timer_) {
    start_ticks_ = TimeTicks::Now();
    message_loop()->timer_manager()->ResetTimer(timer_);
  }
}

void TimerTask::Run() {
  ++iterations_;

  // Test that we fired on or after the delay, not before.
  const TimeTicks ticks = TimeTicks::Now();
  EXPECT_LE(delay_, (ticks - start_ticks_).InMilliseconds());
  // Note: Add the delay rather than using the ticks recorded.
  //       Repeating timers have already started ticking before
  //       this callback; we pretend they started *now*, then
  //       it might seem like they fire early, when they do not.
  start_ticks_ += TimeDelta::FromMilliseconds(delay_);

  // If we're done running, shut down the message loop.
  if (timer_->repeating() && (iterations_ < 10))
    return;  // Iterate 10 times before terminating.
  message_loop()->timer_manager()->StopTimer(timer_);
  timer_running_ = false;
  if (--timer_count_ <= 0)
    QuitMessageLoop();
}

// static
void TimerTask::QuitMessageLoop() {
  if (loop_running_) {
    message_loop()->Quit();
    loop_running_ = false;
  }
}

int TimerTask::timer_count_ = 0;
bool TimerTask::loop_running_ = false;

// A task that deletes itself when run.
class DeletingTask : public TimerTask {
 public:
  DeletingTask(int delay, bool repeating) : TimerTask(delay, repeating) { }

  // Task
  virtual void Run();
};

void DeletingTask::Run() {
  delete this;

  // Can't call TimerTask::Run() here, we've destroyed ourselves.
}

// A class that resets another TimerTask when run.
class ResettingTask : public TimerTask {
 public:
  ResettingTask(int delay, bool repeating, TimerTask* task)
      : TimerTask(delay, repeating),
        task_(task) {
  }

  virtual void Run();

 private:
  TimerTask* task_;
};

void ResettingTask::Run() {
  task_->Reset();

  TimerTask::Run();
}

// A class that quits the message loop when run.
class QuittingTask : public TimerTask {
 public:
  QuittingTask(int delay, bool repeating) : TimerTask(delay, repeating) { }

  virtual void Run();
};

void QuittingTask::Run() {
  QuitMessageLoop();

  TimerTask::Run();
}

void RunTimerTest() {
  // Make sure oneshot timers work correctly.
  TimerTask task1(100, false);
  TimerTask::RunTimers();
  EXPECT_EQ(1, task1.iterations());

  // Make sure repeating timers work correctly.
  TimerTask task2(10, true);
  TimerTask task3(100, true);
  TimerTask::RunTimers();
  EXPECT_EQ(10, task2.iterations());
  EXPECT_EQ(10, task3.iterations());
}

TEST(TimerTest, TimerComparison) {
  // Make sure TimerComparison sorts correctly.
  const TimerTask task1(10, false);
  const Timer* timer1 = task1.timer();
  const TimerTask task2(200, false);
  const Timer* timer2 = task2.timer();
  TimerComparison comparison;
  EXPECT_FALSE(comparison(timer1, timer2));
  EXPECT_TRUE(comparison(timer2, timer1));
}

TEST(TimerTest, TimerCase) {
  RunTimerTest();
}

TEST(TimerTest, BrokenTimerCase) {
  // Simulate faulty early-firing timers. The tasks in RunTimerTest should
  // nevertheless be invoked after their specified delays, regardless of when
  // WM_TIMER fires.
  TimerManager* manager = MessageLoop::current()->timer_manager();
  manager->set_use_broken_delay(true);
  RunTimerTest();
  manager->set_use_broken_delay(false);
}

TEST(TimerTest, DeleteFromRun) {
  // Make sure TimerManager correctly handles a Task that deletes itself when
  // run.
  DeletingTask* deleting_task1 = new DeletingTask(50, true);
  TimerTask timer_task(150, false);
  DeletingTask* deleting_task2 = new DeletingTask(250, true);
  TimerTask::RunTimers();
  EXPECT_EQ(1, timer_task.iterations());
}

TEST(TimerTest, Reset) {
  // Make sure resetting a timer after it has fired works.
  TimerTask timer_task1(250, false);
  TimerTask timer_task2(100, true);
  ResettingTask resetting_task1(600, false, &timer_task1);
  TimerTask::RunTimers();
  EXPECT_EQ(2, timer_task1.iterations());
  EXPECT_EQ(10, timer_task2.iterations());

  // Make sure resetting a timer before it has fired works.  This will reset
  // two timers, then stop the message loop between when they should have
  // finally fired.
  TimerTask timer_task3(100, false);
  TimerTask timer_task4(600, false);
  ResettingTask resetting_task3(50, false, &timer_task3);
  ResettingTask resetting_task4(50, false, &timer_task4);
  QuittingTask quitting_task(300, false);
  TimerTask::RunTimers();
  EXPECT_EQ(1, timer_task3.iterations());
  EXPECT_EQ(0, timer_task4.iterations());
}

TEST(TimerTest, FifoOrder) {
  // Creating timers with the same timeout should
  // always compare to result in FIFO ordering.

  // Derive from the timer so that we can set it's fire time.
  // We have to do this, because otherwise, it's possible for
  // two timers, created back to back, to have different times,
  // and in that case, we aren't really testing what we want
  // to test!
  class MockTimer : public Timer {
   public:
    MockTimer(int delay) : Timer(delay, NULL, false) {}
    void set_fire_time(const Time& t) { fire_time_ = t; }
  };

  class MockTimerManager : public TimerManager {
   public:
    MockTimerManager() : TimerManager(MessageLoop::current()) {
    }
    
    // Pops the most-recent to fire timer and returns its timer id.
    // Returns -1 if there are no timers in the list.
    int pop() {
      int rv = -1;
      Timer* top = PeekTopTimer();
      if (top) {
        rv = top->id();
        StopTimer(top);
        delete top;
      }
      return rv;
    }
  };

  MockTimer t1(0);
  MockTimer t2(0);
  t2.set_fire_time(t1.fire_time());
  TimerComparison comparison;
  EXPECT_TRUE(comparison(&t2, &t1));

  // Issue a tight loop of timers; most will have the
  // same timestamp; some will not.  Either way, since
  // all are created with delay(0), the second timer
  // must always be greater than the first.  Then, pop
  // all the timers and verify that it's a FIFO list.
  MockTimerManager manager;
  const int kNumTimers = 1024;
  for (int i=0; i < kNumTimers; i++)
    Timer* timer = manager.StartTimer(0, NULL, false);

  int last_id = -1;
  int new_id = 0;
  while((new_id = manager.pop()) > 0)
    EXPECT_GT(new_id, last_id);
}