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. 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 <iosfwd>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
+#include "base/synchronization/lock.h"
+#include "base/time.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace internal {
+
+struct TaskEvent {
+  enum Type { POST, START, END };
+  TaskEvent(int i, Type type);
+  int i;
+  Type type;
+};
+
+// Utility class used in the tests below.
+class SequencedTaskTracker : public RefCountedThreadSafe<SequencedTaskTracker> {
+ public:
+  SequencedTaskTracker();
+
+  // Posts the non-nestable task |task|, and records its post event.
+  void PostWrappedNonNestableTask(
+      const scoped_refptr<SequencedTaskRunner>& task_runner,
+      const Closure& task);
+
+  // Posts the nestable task |task|, and records its post event.
+  void PostWrappedNestableTask(
+      const scoped_refptr<SequencedTaskRunner>& task_runner,
+      const Closure& task);
+
+  // Posts the delayed non-nestable task |task|, and records its post event.
+  void PostWrappedDelayedNonNestableTask(
+      const scoped_refptr<SequencedTaskRunner>& task_runner,
+      const Closure& task,
+      TimeDelta delay);
+
+  // Posts |task_count| non-nestable tasks.
+  void PostNonNestableTasks(
+      const scoped_refptr<SequencedTaskRunner>& task_runner,
+      int task_count);
+
+  const std::vector<TaskEvent>& GetTaskEvents() const;
+
+ private:
+  friend class RefCountedThreadSafe<SequencedTaskTracker>;
+
+  ~SequencedTaskTracker();
+
+  // A task which runs |task|, recording the start and end events.
+  void RunTask(const Closure& task, int task_i);
+
+  // Records a post event for task |i|. The owner is expected to be holding
+  // |lock_| (unlike |TaskStarted| and |TaskEnded|).
+  void TaskPosted(int i);
+
+  // Records a start event for task |i|.
+  void TaskStarted(int i);
+
+  // Records a end event for task |i|.
+  void TaskEnded(int i);
+
+  // Protects events_ and next_post_i_.
+  Lock lock_;
+
+  // The events as they occurred for each task (protected by lock_).
+  std::vector<TaskEvent> events_;
+
+  // The ordinal to be used for the next task-posting task (protected by
+  // lock_).
+  int next_post_i_;
+
+  DISALLOW_COPY_AND_ASSIGN(SequencedTaskTracker);
+};
+
+void PrintTo(const TaskEvent& event, std::ostream* os);
+
+void SleepForOneSecond();
+
+// Checks the non-nestable task invariants for all tasks in |events|.
+//
+// The invariants are:
+// 1) Events started and ended in the same order that they were posted.
+// 2) Events for an individual tasks occur in the order {POST, START, END},
+//    and there is only one instance of each event type for a task.
+// 3) The only events between a task's START and END events are the POSTs of
+//    other tasks. I.e. tasks were run sequentially, not interleaved.
+::testing::AssertionResult CheckNonNestableInvariants(
+    const std::vector<TaskEvent>& events,
+    int task_count);
+
+}  // 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. I.e. that each task starts only after the previously-posted
+// one has finished.
+TYPED_TEST_P(SequencedTaskRunnerTest, SequentialNonNestable) {
+  const int task_count = 1000;
+
+  this->delegate_.StartTaskRunner();
+  const scoped_refptr<SequencedTaskRunner> task_runner =
+      this->delegate_.GetTaskRunner();
+
+  this->task_tracker_->PostWrappedNonNestableTask(
+      task_runner, Bind(&internal::SleepForOneSecond));
+  for (int i = 1; i < task_count; ++i) {
+    this->task_tracker_->PostWrappedNonNestableTask(task_runner, Closure());
+  }
+
+  this->delegate_.StopTaskRunner();
+
+  EXPECT_TRUE(CheckNonNestableInvariants(this->task_tracker_->GetTaskEvents(),
+                                         task_count));
+}
+
+// This test posts N nestable tasks in sequence. It has the same expectations
+// as SequentialNonNestable because even though the tasks are nestable, they
+// will not be run nestedly in this case.
+TYPED_TEST_P(SequencedTaskRunnerTest, SequentialNestable) {
+  const int task_count = 1000;
+
+  this->delegate_.StartTaskRunner();
+  const scoped_refptr<SequencedTaskRunner> task_runner =
+      this->delegate_.GetTaskRunner();
+
+  this->task_tracker_->PostWrappedNestableTask(
+      task_runner,
+      Bind(&internal::SleepForOneSecond));
+  for (int i = 1; i < task_count; ++i) {
+    this->task_tracker_->PostWrappedNestableTask(task_runner, Closure());
+  }
+
+  this->delegate_.StopTaskRunner();
+
+  EXPECT_TRUE(CheckNonNestableInvariants(this->task_tracker_->GetTaskEvents(),
+                                         task_count));
+}
+
+// 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.
+TYPED_TEST_P(SequencedTaskRunnerTest, SequentialDelayedNonNestable) {
+  if (!this->delegate_.TaskRunnerHandlesNonZeroDelays()) {
+    DLOG(INFO) << "This SequencedTaskRunner doesn't handle "
+        "non-zero delays; skipping";
+    return;
+  }
+
+  const int task_count = 20;
+  const int delay_increment_ms = 50;
+
+  this->delegate_.StartTaskRunner();
+  const scoped_refptr<SequencedTaskRunner> task_runner =
+      this->delegate_.GetTaskRunner();
+
+  for (int i = 0; i < task_count; ++i) {
+    this->task_tracker_->PostWrappedDelayedNonNestableTask(
+        task_runner,
+        Closure(),
+        TimeDelta::FromMilliseconds(delay_increment_ms * i));
+  }
+
+  this->delegate_.StopTaskRunner();
+
+  EXPECT_TRUE(CheckNonNestableInvariants(this->task_tracker_->GetTaskEvents(),
+                                         task_count));
+}
+
+// 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 = 10;
+  const int children_per_parent = 10;
+
+  this->delegate_.StartTaskRunner();
+  const scoped_refptr<SequencedTaskRunner> task_runner =
+      this->delegate_.GetTaskRunner();
+
+  for (int i = 0; i < parent_count; ++i) {
+    Closure task = Bind(
+        &internal::SequencedTaskTracker::PostNonNestableTasks,
+        this->task_tracker_,
+        task_runner,
+        children_per_parent);
+    this->task_tracker_->PostWrappedNonNestableTask(task_runner, task);
+  }
+
+  this->delegate_.StopTaskRunner();
+
+  EXPECT_TRUE(CheckNonNestableInvariants(
+      this->task_tracker_->GetTaskEvents(),
+      parent_count * (children_per_parent + 1)));
+}
+
+// TODO(francoisk777@gmail.com) Add a test, similiar to the above, 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,
+                           SequentialNestable,
+                           SequentialDelayedNonNestable,
+                           NonNestablePostFromNonNestableTask);
+
+}  // namespace base
+
+#endif  // BASE_TASK_RUNNER_TEST_TEMPLATE_H_