Implementation of SequencedTaskRunner based on SequencedWorkerPool.

base/test/sequenced_task_runner_test_template.h

+// Copyright (c) 2012 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.
+
+// This class defines tests that implementations of SequencedTaskRunner should
+// pass in order to be conformant.  Here's how you use it to test your
+// implementation.
+//
+// See task_runner_test_template.h for a description of how to use the
+// constructs in this file; these work the same.
+
+#ifndef BASE_SEQUENCED_TASK_RUNNER_TEST_TEMPLATE_H_
+#define BASE_SEQUENCED_TASK_RUNNER_TEST_TEMPLATE_H_
+#pragma once
+
+#include <cstddef>
+
+#include <algorithm>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
+#include "base/synchronization/lock.h"
+#include "base/tracked_objects.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace internal {
+
+// Utility class used in the tests below.
+class SequencedTaskTracker : public RefCountedThreadSafe<SequencedTaskTracker> {
+ public:
+  SequencedTaskTracker();
+
+  int GetNextPostOrdinal();
+
+  void TaskPosted(int i);
+  void TaskStarted(int i);
+  void TaskEnded(int i);
+
+  const std::vector<int>& GetPostOrder() const;
+  const std::vector<int>& GetStartOrder() const;
+  const std::vector<int>& GetEndOrder() const;
+
+  void FastTask(int i);
+  void SlowTask(int i);
+
+  // Task which posts a fast, non-nestable task.
+  void PostFastNonNestableFromSlowNonNestable(
+      scoped_refptr<SequencedTaskRunner> task_runner,
+      const int base_status_i,
+      const int child_count);
+
+ private:
+  friend class RefCountedThreadSafe<SequencedTaskTracker>;
+
+  ~SequencedTaskTracker();
+
+ public:
+  std::vector<int> post_events_;
+  mutable Lock post_lock_;
+
+ private:
+  std::vector<int> start_events_;
+  mutable Lock start_lock_;
+
+  std::vector<int> end_events_;
+  mutable Lock end_lock_;
+
+  int next_post_i_;
+
+  DISALLOW_COPY_AND_ASSIGN(SequencedTaskTracker);
+};
+
+}  // namespace internal
+
+template <typename TaskRunnerTestDelegate>
+class SequencedTaskRunnerTest : public testing::Test {
+ protected:
+  SequencedTaskRunnerTest()
+  : task_tracker_(new internal::SequencedTaskTracker()) {}
+
+  const scoped_refptr<internal::SequencedTaskTracker> task_tracker_;
+  TaskRunnerTestDelegate delegate_;
+};
+
+TYPED_TEST_CASE_P(SequencedTaskRunnerTest);
+
+// This test posts N non-nestable tasks in sequence, and expects them to run
+// in FIFO order, with no part of any two tasks' execution overlapping.
+//
+// It checks that task0 was done by the time task1 started, and task2 only
+// started after task1 had executed to completion, etc.
+//
+// The first task it starts is a slow one which runs for a second, giving the
+// subsequent ones plenty of time to run if the implementation fails to
+// enforce the non-nestable property.
+TYPED_TEST_P(SequencedTaskRunnerTest, SequentialNonNestable) {
+  const int task_count = 1000;
+
+  this->delegate_.StartTaskRunner();
+  scoped_refptr<SequencedTaskRunner> task_runner =
+      this->delegate_.GetTaskRunner();
+
+  for (int i = 0; i < task_count; ++i) {
+    Closure task;
+    if (i == 0) {
+      task = Bind(&internal::SequencedTaskTracker::SlowTask,
+                  this->task_tracker_, i);
+    } else {
+      task = Bind(&internal::SequencedTaskTracker::FastTask,
+                  this->task_tracker_, i);
+    }
+    this->task_tracker_->TaskPosted(i);
+    task_runner->PostNonNestableTask(FROM_HERE, task);
+  }
+
+  this->delegate_.StopTaskRunner();
+
+  EXPECT_EQ(this->task_tracker_->GetPostOrder(),
+            this->task_tracker_->GetStartOrder());
+  EXPECT_EQ(this->task_tracker_->GetEndOrder(),
+            this->task_tracker_->GetStartOrder());
+}
+
+// This test posts N nestable tasks in sequence, and expects them to run in
+// FIFO order; overlapping execution is allowed.
+//
+// It checks only that task_i had started by the time task_i+1 started, for
+// increasing values of i. Thus it verifies the SequencedTaskRunner guarantee
+// that nested tasks are run in FIFO order.
+//
+// The first task it starts is a slow one which runs for a second, giving the
+// subsequent ones plenty of time to run in if the implementation fails to
+// enforce the FIFO property for nestable tasks.
+TYPED_TEST_P(SequencedTaskRunnerTest, FAILS_SequentialNestable) {
+  const int task_count = 10;
+
+  this->delegate_.StartTaskRunner();
+  scoped_refptr<SequencedTaskRunner> task_runner =
+      this->delegate_.GetTaskRunner();
+
+  for (int i = 0; i < task_count; ++i) {
+    Closure task;
+    if (i == 0) {
+      task = Bind(&internal::SequencedTaskTracker::SlowTask,
+                  this->task_tracker_, i);
+    } else {
+      task = Bind(&internal::SequencedTaskTracker::FastTask,
+                  this->task_tracker_, i);
+    }
+    this->task_tracker_->TaskPosted(i);
+    task_runner->PostTask(FROM_HERE, task);
+  }
+
+  this->delegate_.StopTaskRunner();
+
+  const std::vector<int>& post_events = this->task_tracker_->GetPostOrder();
+  const std::vector<int>& end_events = this->task_tracker_->GetEndOrder();
+
+  EXPECT_EQ(post_events, this->task_tracker_->GetStartOrder());
+
+  // Check that all posted tasks finished.
+  for (std::size_t i = 0; i < post_events.size(); ++i) {
+    EXPECT_NE(std::find(end_events.begin(), end_events.end(), post_events[i]),
+              end_events.end());
+  }
+}
+
+// This test posts non-nestable tasks in order of increasing delay, and checks
+// that that the tasks are run in FIFO order and that there is no execution
+// overlap whatsoever between any two tasks.
+//
+// If there are 10 tasks, task1 is posted first with a delay of zero, followed
+// by task2 with a delay of, say, 1, and so forth, until task10 is posted with
+// a delay of 10. It then checks that task2 started after task1, and only
+// after task1 had finished, and so forth.
+TYPED_TEST_P(SequencedTaskRunnerTest, SequentialDelayedNonNestable) {
+  const int task_count = 20;
+  const int delay_increment_ms = 50;
+
+  this->delegate_.StartTaskRunner();
+  scoped_refptr<SequencedTaskRunner> task_runner =
+      this->delegate_.GetTaskRunner();
+
+  for (int i = 0; i < task_count; ++i) {
+    Closure task = Bind(&internal::SequencedTaskTracker::FastTask,
+                        this->task_tracker_, i);
+    this->task_tracker_->TaskPosted(i);
+    task_runner->PostNonNestableDelayedTask(
+        FROM_HERE,
+        task,
+        TimeDelta::FromMilliseconds(delay_increment_ms * i));
+  }
+
+  this->delegate_.StopTaskRunner();
+
+  EXPECT_EQ(this->task_tracker_->GetPostOrder(),
+            this->task_tracker_->GetStartOrder());
+  EXPECT_EQ(this->task_tracker_->GetStartOrder(),
+            this->task_tracker_->GetEndOrder());
+}
+
+// This test posts a fast, non-nestable task from within each of a number of
+// slow, non-nestable tasks and checks that they all run in the sequence they
+// were posted in and that there is no execution overlap whatsoever.
+TYPED_TEST_P(SequencedTaskRunnerTest, NonNestablePostFromNonNestableTask) {
+  const int parent_count = 1000;
+  const int children_per_parent = 2;
+
+  this->delegate_.StartTaskRunner();
+  scoped_refptr<SequencedTaskRunner> task_runner =
+      this->delegate_.GetTaskRunner();
+
+  const int end = parent_count;
+  for (int i = 0; i < end; ++i) {
+    base::PlatformThread::YieldCurrentThread();
+    AutoLock post_lock(this->task_tracker_->post_lock_);
+    const int post_i = this->task_tracker_->GetNextPostOrdinal();
+    Closure task = Bind(
+        &internal::SequencedTaskTracker::PostFastNonNestableFromSlowNonNestable,
+        this->task_tracker_,
+        task_runner,
+        post_i,
+        children_per_parent);
+    this->task_tracker_->post_events_.push_back(post_i);
+    task_runner->PostNonNestableTask(FROM_HERE, task);

[Francois, 2012/03/18 16:28:29]

The loop body is messy, but I want to hear your comments before I change this.

+  }
+
+  this->delegate_.StopTaskRunner();
+
+  EXPECT_EQ(this->task_tracker_->GetPostOrder(),
+            this->task_tracker_->GetStartOrder());
+  EXPECT_EQ(this->task_tracker_->GetEndOrder(),
+            this->task_tracker_->GetStartOrder());
+}
+
+// TODO(francoisk777@gmail.com) Add a test, similiar to the above, which which
+// runs some tasked nestedly (which should be implemented in the test
+// delegate). Also add, to the the test delegate, a predicate which checks
+// whether the implementation supports nested tasks.
+
+REGISTER_TYPED_TEST_CASE_P(SequencedTaskRunnerTest,
+                           SequentialNonNestable,
+                           FAILS_SequentialNestable,
+                           SequentialDelayedNonNestable,
+                           NonNestablePostFromNonNestableTask);
+
+}  // namespace base
+
+#endif  // BASE_TASK_RUNNER_TEST_TEMPLATE_H_