TaskScheduler: Add FlushForTesting().

base/task_scheduler/task_tracker_unittest.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/task_scheduler/task_tracker.h"
 
 #include <stdint.h>
 
 #include <memory>
 #include <vector>
 
 #include "base/bind.h"
+#include "base/callback.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/sequence_token.h"
 #include "base/sequenced_task_runner.h"
 #include "base/single_thread_task_runner.h"
+#include "base/synchronization/atomic_flag.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/task_scheduler/scheduler_lock.h"
 #include "base/task_scheduler/task.h"
 #include "base/task_scheduler/task_traits.h"
 #include "base/test/gtest_util.h"
 #include "base/test/test_simple_task_runner.h"
+#include "base/test/test_timeouts.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/sequenced_task_runner_handle.h"
 #include "base/threading/simple_thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 namespace internal {
 
 namespace {
 
 constexpr size_t kLoadTestNumIterations = 100;
 
-// Calls TaskTracker::Shutdown() asynchronously.
-class ThreadCallingShutdown : public SimpleThread {
+// Invokes a closure asynchronously.
+class CallbackThread : public SimpleThread {
  public:
-  explicit ThreadCallingShutdown(TaskTracker* tracker)
-      : SimpleThread("ThreadCallingShutdown"),
-        tracker_(tracker),
-        has_returned_(WaitableEvent::ResetPolicy::MANUAL,
-                      WaitableEvent::InitialState::NOT_SIGNALED) {}
+  explicit CallbackThread(const Closure& closure)
+      : SimpleThread("CallbackThread"), closure_(closure) {}
 
   // Returns true once the async call to Shutdown() has returned.

[danakj, 2016/09/23 20:51:41]

Comment needs updating

[fdoray, 2016/09/23 21:09:46]

Done.

-  bool has_returned() { return has_returned_.IsSignaled(); }
+  bool has_returned() { return has_returned_.IsSet(); }
 
  private:
   void Run() override {
-    tracker_->Shutdown();
-    has_returned_.Signal();
+    closure_.Run();
+    has_returned_.Set();
   }
 
-  TaskTracker* const tracker_;
-  WaitableEvent has_returned_;
+  const Closure closure_;
+  AtomicFlag has_returned_;
 
-  DISALLOW_COPY_AND_ASSIGN(ThreadCallingShutdown);
+  DISALLOW_COPY_AND_ASSIGN(CallbackThread);
 };
 
 class ThreadPostingAndRunningTask : public SimpleThread {
  public:
   enum class Action {
     WILL_POST,
     RUN,
     WILL_POST_AND_RUN,
   };
 
@@ skipping 52 matching lines @@
         FROM_HERE,
         Bind(&TaskSchedulerTaskTrackerTest::RunTaskCallback, Unretained(this)),
         TaskTraits().WithShutdownBehavior(shutdown_behavior), TimeDelta());
   }
 
   // Calls tracker_->Shutdown() on a new thread. When this returns, Shutdown()
   // method has been entered on the new thread, but it hasn't necessarily
   // returned.
   void CallShutdownAsync() {
     ASSERT_FALSE(thread_calling_shutdown_);
-    thread_calling_shutdown_.reset(new ThreadCallingShutdown(&tracker_));
+    thread_calling_shutdown_.reset(new CallbackThread(
+        Bind(&TaskTracker::Shutdown, Unretained(&tracker_))));
     thread_calling_shutdown_->Start();
     while (!tracker_.HasShutdownStarted())
       PlatformThread::YieldCurrentThread();
   }
 
   void WaitForAsyncIsShutdownComplete() {
     ASSERT_TRUE(thread_calling_shutdown_);
     thread_calling_shutdown_->Join();
     EXPECT_TRUE(thread_calling_shutdown_->has_returned());
     EXPECT_TRUE(tracker_.IsShutdownComplete());
   }
 
   void VerifyAsyncShutdownInProgress() {
     ASSERT_TRUE(thread_calling_shutdown_);
     EXPECT_FALSE(thread_calling_shutdown_->has_returned());
     EXPECT_TRUE(tracker_.HasShutdownStarted());
     EXPECT_FALSE(tracker_.IsShutdownComplete());
   }
 
+  // Calls tracker_->FlushForTesting() on a new thread.
+  void CallFlushForTestingAsync() {
+    ASSERT_FALSE(thread_calling_flush_for_testing_);
+    thread_calling_flush_for_testing_.reset(new CallbackThread(
+        Bind(&TaskTracker::FlushForTesting, Unretained(&tracker_))));
+    thread_calling_flush_for_testing_->Start();
+  }
+
+  void WaitForAsyncFlushForTestingReturned() {
+    ASSERT_TRUE(thread_calling_flush_for_testing_);
+    thread_calling_flush_for_testing_->Join();
+    EXPECT_TRUE(thread_calling_flush_for_testing_->has_returned());
+  }
+
+  void VerifyAsyncFlushForTestingInProgress() {
+    ASSERT_TRUE(thread_calling_flush_for_testing_);
+    EXPECT_FALSE(thread_calling_flush_for_testing_->has_returned());
+  }
+
   size_t NumTasksExecuted() {
     AutoSchedulerLock auto_lock(lock_);
     return num_tasks_executed_;
   }
 
   TaskTracker tracker_;
 
  private:
   void RunTaskCallback() {
     AutoSchedulerLock auto_lock(lock_);
     ++num_tasks_executed_;
   }
 
-  std::unique_ptr<ThreadCallingShutdown> thread_calling_shutdown_;
+  std::unique_ptr<CallbackThread> thread_calling_shutdown_;
+  std::unique_ptr<CallbackThread> thread_calling_flush_for_testing_;
 
   // Synchronizes accesses to |num_tasks_executed_|.
   SchedulerLock lock_;
 
   size_t num_tasks_executed_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(TaskSchedulerTaskTrackerTest);
 };
 
 #define WAIT_FOR_ASYNC_SHUTDOWN_COMPLETED() \
   do {                                      \
     SCOPED_TRACE("");                       \
     WaitForAsyncIsShutdownComplete();       \
   } while (false)
 
 #define VERIFY_ASYNC_SHUTDOWN_IN_PROGRESS() \
   do {                                      \
     SCOPED_TRACE("");                       \
     VerifyAsyncShutdownInProgress();        \
   } while (false)
 
+#define WAIT_FOR_ASYNC_FLUSH_FOR_TESTING_RETURNED() \
+  do {                                              \
+    SCOPED_TRACE("");                               \
+    WaitForAsyncFlushForTestingReturned();          \
+  } while (false)
+
+#define VERIFY_ASYNC_FLUSH_FOR_TESTING_IN_PROGRESS() \
+  do {                                               \
+    SCOPED_TRACE("");                                \
+    VerifyAsyncFlushForTestingInProgress();          \
+  } while (false)
+
 }  // namespace
 
 TEST_P(TaskSchedulerTaskTrackerTest, WillPostAndRunBeforeShutdown) {
   std::unique_ptr<Task> task(CreateTask(GetParam()));
 
   // Inform |task_tracker_| that |task| will be posted.
   EXPECT_TRUE(tracker_.WillPostTask(task.get()));
 
   // Run the task.
   EXPECT_EQ(0U, NumTasksExecuted());
@@ skipping 249 matching lines @@
   // being set on it.
   std::unique_ptr<Task> verify_task(
       new Task(FROM_HERE, Bind(&VerifyThreadTaskRunnerHandle,
                                base::Unretained(test_task_runner.get())),
                TaskTraits().WithShutdownBehavior(GetParam()), TimeDelta()));
   verify_task->single_thread_task_runner_ref = test_task_runner;
 
   RunTaskRunnerHandleVerificationTask(&tracker_, std::move(verify_task));
 }
 
+TEST_P(TaskSchedulerTaskTrackerTest, FlushForTestingPendingDelayedTask) {
+  const Task delayed_task(FROM_HERE, Bind(&DoNothing),
+                          TaskTraits().WithShutdownBehavior(GetParam()),
+                          TimeDelta::FromDays(1));
+  tracker_.WillPostTask(&delayed_task);
+  // FlushForTesting() should return even if the delayed task didn't run.
+  tracker_.FlushForTesting();
+}
+
+TEST_P(TaskSchedulerTaskTrackerTest, FlushForTestingPendingUndelayedTask) {
+  const Task undelayed_task(FROM_HERE, Bind(&DoNothing),
+                            TaskTraits().WithShutdownBehavior(GetParam()),
+                            TimeDelta());
+  tracker_.WillPostTask(&undelayed_task);
+
+  // FlushForTesting() shouldn't return before the undelayed task runs.
+  CallFlushForTestingAsync();
+  PlatformThread::Sleep(TestTimeouts::tiny_timeout());
+  VERIFY_ASYNC_FLUSH_FOR_TESTING_IN_PROGRESS();
+
+  // FlushForTesting() should return after the undelayed task runs.
+  tracker_.RunTask(&undelayed_task, SequenceToken::Create());
+  WAIT_FOR_ASYNC_FLUSH_FOR_TESTING_RETURNED();
+}
+
+TEST_P(TaskSchedulerTaskTrackerTest, PostTaskDuringFlushForTesting) {
+  const Task undelayed_task(FROM_HERE, Bind(&DoNothing),
+                            TaskTraits().WithShutdownBehavior(GetParam()),
+                            TimeDelta());
+  tracker_.WillPostTask(&undelayed_task);
+
+  // FlushForTesting() shouldn't return before the undelayed task runs.
+  CallFlushForTestingAsync();
+  PlatformThread::Sleep(TestTimeouts::tiny_timeout());
+  VERIFY_ASYNC_FLUSH_FOR_TESTING_IN_PROGRESS();
+
+  // Simulate posting another undelayed task.
+  const Task other_undelayed_task(FROM_HERE, Bind(&DoNothing),
+                                  TaskTraits().WithShutdownBehavior(GetParam()),
+                                  TimeDelta());
+  tracker_.WillPostTask(&other_undelayed_task);
+
+  // Run the first undelayed task.
+  tracker_.RunTask(&undelayed_task, SequenceToken::Create());
+
+  // FlushForTesting() shouldn't return before the second undelayed task runs.
+  PlatformThread::Sleep(TestTimeouts::tiny_timeout());
+  VERIFY_ASYNC_FLUSH_FOR_TESTING_IN_PROGRESS();
+
+  // FlushForTesting() should return after the second undelayed task runs.
+  tracker_.RunTask(&other_undelayed_task, SequenceToken::Create());
+  WAIT_FOR_ASYNC_FLUSH_FOR_TESTING_RETURNED();
+}
+
+TEST_P(TaskSchedulerTaskTrackerTest, RunDelayedTaskDuringFlushForTesting) {
+  // Simulate posting a delayed and an undelayed task.
+  const Task delayed_task(FROM_HERE, Bind(&DoNothing),
+                          TaskTraits().WithShutdownBehavior(GetParam()),
+                          TimeDelta::FromDays(1));
+  tracker_.WillPostTask(&delayed_task);
+  const Task undelayed_task(FROM_HERE, Bind(&DoNothing),
+                            TaskTraits().WithShutdownBehavior(GetParam()),
+                            TimeDelta());
+  tracker_.WillPostTask(&undelayed_task);
+
+  // FlushForTesting() shouldn't return before the undelayed task runs.
+  CallFlushForTestingAsync();
+  PlatformThread::Sleep(TestTimeouts::tiny_timeout());
+  VERIFY_ASYNC_FLUSH_FOR_TESTING_IN_PROGRESS();
+
+  // Run the delayed task.
+  tracker_.RunTask(&delayed_task, SequenceToken::Create());
+
+  // FlushForTesting() shouldn't return since there is still a pending undelayed
+  // task.
+  PlatformThread::Sleep(TestTimeouts::tiny_timeout());
+  VERIFY_ASYNC_FLUSH_FOR_TESTING_IN_PROGRESS();
+
+  // Run the undelayed task.
+  tracker_.RunTask(&undelayed_task, SequenceToken::Create());
+
+  // FlushForTesting() should now return.
+  WAIT_FOR_ASYNC_FLUSH_FOR_TESTING_RETURNED();
+}
+
+TEST_P(TaskSchedulerTaskTrackerTest, FlushForTestingAfterShutdown) {
+  if (GetParam() == TaskShutdownBehavior::BLOCK_SHUTDOWN)
+    return;
+
+  // Simulate posting a task.
+  const Task undelayed_task(FROM_HERE, Bind(&DoNothing),
+                            TaskTraits().WithShutdownBehavior(GetParam()),
+                            TimeDelta());
+  tracker_.WillPostTask(&undelayed_task);
+
+  // Shutdown() should return immediately since there are no pending
+  // BLOCK_SHUTDOWN tasks.
+  tracker_.Shutdown();
+
+  // FlushForTesting() should return immediately after shutdown, even if an
+  // undelayed task hasn't run.
+  tracker_.FlushForTesting();
+}
+
+TEST_P(TaskSchedulerTaskTrackerTest, ShutdownDuringFlushForTesting) {
+  if (GetParam() == TaskShutdownBehavior::BLOCK_SHUTDOWN)
+    return;
+
+  // Simulate posting a task.
+  const Task undelayed_task(FROM_HERE, Bind(&DoNothing),
+                            TaskTraits().WithShutdownBehavior(GetParam()),
+                            TimeDelta());
+  tracker_.WillPostTask(&undelayed_task);
+
+  // FlushForTesting() shouldn't return before the undelayed task runs or
+  // shutdown completes.
+  CallFlushForTestingAsync();
+  PlatformThread::Sleep(TestTimeouts::tiny_timeout());
+  VERIFY_ASYNC_FLUSH_FOR_TESTING_IN_PROGRESS();
+
+  // Shutdown() should return immediately since there are no pending
+  // BLOCK_SHUTDOWN tasks.
+  tracker_.Shutdown();
+
+  // FlushForTesting() should now return, even if an undelayed task hasn't run.
+  WAIT_FOR_ASYNC_FLUSH_FOR_TESTING_RETURNED();
+}
+
 INSTANTIATE_TEST_CASE_P(
     ContinueOnShutdown,
     TaskSchedulerTaskTrackerTest,
     ::testing::Values(TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN));
 INSTANTIATE_TEST_CASE_P(
     SkipOnShutdown,
     TaskSchedulerTaskTrackerTest,
     ::testing::Values(TaskShutdownBehavior::SKIP_ON_SHUTDOWN));
 INSTANTIATE_TEST_CASE_P(
     BlockShutdown,
@@ skipping 152 matching lines @@
 
   // Unblock shutdown by running |block_shutdown_task|.
   EXPECT_TRUE(
       tracker_.RunTask(block_shutdown_task.get(), SequenceToken::Create()));
   EXPECT_EQ(kLoadTestNumIterations + 1, NumTasksExecuted());
   WAIT_FOR_ASYNC_SHUTDOWN_COMPLETED();
 }
 
 }  // namespace internal
 }  // namespace base