Implementation of SequencedTaskRunner based on SequencedWorkerPool.

base/test/sequenced_task_runner_test_template.cc

+// 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.
+
+#include "base/test/sequenced_task_runner_test_template.h"
+
+#include <ostream>

[Francois, 2012/03/26 09:33:21]

For SequencedTaskTracker::TaskEvent::PrintTo, which takes a std::ostream
argument.

+
+#include "base/tracked_objects.h"

[akalin, 2012/03/26 18:44:08]

looks like this should be base/location.h (this changed recently)

[Francois, 2012/03/28 14:32:42]

Done.

+
+namespace base {
+
+namespace internal {
+
+SequencedTaskTracker::TaskEvent::TaskEvent(int i_in, Type type_in)

[akalin, 2012/03/26 18:44:08]

don't use _in, just name them the same; C++'s variable lookup rules are such
that ": i(i), type(type)" works correctly.

[Francois, 2012/03/28 14:32:42]

Done.

+  : i(i_in), type(type_in) {
+}
+
+SequencedTaskTracker::SequencedTaskTracker() : next_post_i_(0) {
+}
+
+void SequencedTaskTracker::PostWrappedNonNestableTask(
+    const scoped_refptr<SequencedTaskRunner>& task_runner,
+    const Closure& task) {
+  AutoLock event_lock(lock_);
+  const int post_i = next_post_i_++;
+  Closure wrapped_task = Bind(&SequencedTaskTracker::RunTask, this,
+                              task, post_i);
+  task_runner->PostNonNestableTask(FROM_HERE, wrapped_task);
+  TaskPosted(post_i);
+}
+
+void SequencedTaskTracker::PostWrappedNestableTask(
+    const scoped_refptr<SequencedTaskRunner>& task_runner,
+    const Closure& task) {
+  AutoLock event_lock(lock_);
+  const int post_i = next_post_i_++;
+  Closure wrapped_task = Bind(&SequencedTaskTracker::RunTask, this,
+                              task, post_i);
+  task_runner->PostTask(FROM_HERE, wrapped_task);
+  TaskPosted(post_i);
+}
+
+void SequencedTaskTracker::PostWrappedDelayedNonNestableTask(
+    const scoped_refptr<SequencedTaskRunner>& task_runner,
+    const Closure& task,
+    TimeDelta delay) {
+  AutoLock event_lock(lock_);
+  const int post_i = next_post_i_++;
+  Closure wrapped_task = Bind(&SequencedTaskTracker::RunTask, this,
+                              task, post_i);
+  task_runner->PostNonNestableDelayedTask(FROM_HERE, wrapped_task, delay);
+  TaskPosted(post_i);
+}
+
+void SequencedTaskTracker::PostNonNestableTasks(
+    const scoped_refptr<SequencedTaskRunner>& task_runner,
+    int task_count) {
+  for (int i = 0; i < task_count; ++i) {
+    PostWrappedNonNestableTask(task_runner, Closure());
+  }
+}
+
+void SequencedTaskTracker::RunTask(const Closure& task, int task_i) {
+  TaskStarted(task_i);
+  if (!task.is_null())
+    task.Run();
+  TaskEnded(task_i);
+}
+
+void SequencedTaskTracker::TaskPosted(int i) {
+  // Caller must own |lock_|.
+  events_.push_back(TaskEvent(i, TaskEvent::POST));
+}
+
+void SequencedTaskTracker::TaskStarted(int i) {
+  AutoLock lock(lock_);
+  events_.push_back(TaskEvent(i, TaskEvent::START));
+}
+
+void SequencedTaskTracker::TaskEnded(int i) {
+  AutoLock lock(lock_);
+  events_.push_back(TaskEvent(i, TaskEvent::END));
+}
+
+const std::vector<SequencedTaskTracker::TaskEvent>&
+SequencedTaskTracker::GetTaskEvents() const {
+  return events_;
+}
+
+SequencedTaskTracker::~SequencedTaskTracker() {
+}
+
+void PrintTo(const SequencedTaskTracker::TaskEvent& event, std::ostream* os) {
+  *os << "(i=" << event.i << ", type=";
+  switch (event.type) {
+    case SequencedTaskTracker::TaskEvent::POST: *os << "POST"; break;
+    case SequencedTaskTracker::TaskEvent::START: *os << "START"; break;
+    case SequencedTaskTracker::TaskEvent::END: *os << "END"; break;
+  }
+  *os << ")";
+}
+
+void SleepForOneSecond() {
+  base::PlatformThread::Sleep(base::TimeDelta::FromSeconds(1));
+}
+
+typedef SequencedTaskTracker::TaskEvent TaskEvent;
+
+namespace {
+
+// Returns the task ordinals for the task event type |type| in the order that
+// they were recorded.
+std::vector<int> GetEventTypeOrder(const std::vector<TaskEvent>& events,
+                                   TaskEvent::Type type) {
+  std::vector<int> tasks;
+  std::vector<TaskEvent>::const_iterator event;
+  for (event = events.begin(); event != events.end(); ++event) {
+    if (event->type == type)
+      tasks.push_back(event->i);
+  }
+  return tasks;
+}
+
+// Returns all task events for task |task_i|.
+std::vector<TaskEvent::Type> GetEventsForTask(
+    const std::vector<TaskEvent>& events,
+    int task_i) {
+  std::vector<TaskEvent::Type> task_event_orders;
+  std::vector<TaskEvent>::const_iterator event;
+  for (event = events.begin(); event != events.end(); ++event) {
+    if (event->i == task_i)
+      task_event_orders.push_back(event->type);
+  }
+  return task_event_orders;
+}
+
+// Checks that the task events for each task in |events| occur in the order
+// {POST, START, END}, and that there is only one instance of each event type
+// per task.
+::testing::AssertionResult CheckEventOrdersForEachTask(
+    const std::vector<TaskEvent>& events,
+    int task_count) {
+  std::vector<TaskEvent::Type> expected_order;
+  expected_order.push_back(TaskEvent::POST);
+  expected_order.push_back(TaskEvent::START);
+  expected_order.push_back(TaskEvent::END);
+
+  for (int i = 0; i < task_count; ++i) {

[akalin, 2012/03/26 18:44:08]

This takes n^2 time, which isn't great but probably not worth optimizing.  But
should still add a comment about it.

[Francois, 2012/03/28 14:32:42]

Done.

+    const std::vector<TaskEvent::Type> task_events =
+        GetEventsForTask(events, i);
+    if (task_events != expected_order) {
+      return ::testing::AssertionFailure()
+          << "Events for task " << i << " are out of order; expected: "
+          << ::testing::PrintToString(expected_order) << "; actual: "
+          << ::testing::PrintToString(task_events);
+    }
+  }
+  return ::testing::AssertionSuccess();
+}
+
+// Checks that no two tasks were running at the same time. I.e. the only
+// events allowed between the START and END of a task are the POSTs of other
+// tasks.
+::testing::AssertionResult CheckNoTaskRunsOverlap(
+    const std::vector<TaskEvent>& events) {
+  // If > -1, we're currently inside a START, END pair.
+  int current_task_i = -1;
+
+  std::vector<TaskEvent>::const_iterator event;
+  for (event = events.begin(); event != events.end(); ++event) {
+    bool spurious_event_found = false;
+
+    if (current_task_i == -1) {  // Not inside a START, END pair.
+      switch (event->type) {
+        case TaskEvent::POST:
+          break;
+        case TaskEvent::START:
+          current_task_i = event->i;
+          break;
+        case TaskEvent::END:
+          spurious_event_found = true;
+          break;
+      }
+
+    } else {  // Inside a START, END pair.
+      bool interleaved_task_detected = false;
+
+      switch (event->type) {
+        case TaskEvent::POST:
+          if (event->i == current_task_i)
+            spurious_event_found = true;
+          break;
+        case TaskEvent::START:
+          interleaved_task_detected = true;
+          break;
+        case TaskEvent::END:
+          if (event->i != current_task_i)
+            interleaved_task_detected = true;
+          else
+            current_task_i = -1;
+          break;
+      }
+
+      if (interleaved_task_detected) {
+        return ::testing::AssertionFailure()
+            << "Found event " << ::testing::PrintToString(*event)
+            << " between START and END events for task " << current_task_i
+            << "; event dump: " << ::testing::PrintToString(events);
+      }
+    }
+
+    if (spurious_event_found) {
+      const int event_i = event - events.begin();
+      return ::testing::AssertionFailure()
+          << "Spurious event " << ::testing::PrintToString(*event)
+          << " at position " << event_i << "; event dump: "
+          << ::testing::PrintToString(events);
+    }
+  }
+
+  return ::testing::AssertionSuccess();
+}
+
+}  // namespace
+
+::testing::AssertionResult CheckNonNestableInvariants(
+    const std::vector<TaskEvent>& events,
+    int task_count) {
+  const std::vector<int> post_order =
+      GetEventTypeOrder(events, TaskEvent::POST);
+  const std::vector<int> start_order =
+      GetEventTypeOrder(events, TaskEvent::START);
+  const std::vector<int> end_order =
+      GetEventTypeOrder(events, TaskEvent::END);
+
+  if (start_order != post_order) {
+    return ::testing::AssertionFailure()
+        << "Expected START order (which equals actual POST order): \n"
+        << ::testing::PrintToString(post_order)
+        << "\n Actual START order:\n"
+        << ::testing::PrintToString(start_order);
+  }
+
+  if (end_order != post_order) {
+    return ::testing::AssertionFailure()
+        << "Expected END order (which equals actual POST order): \n"
+        << ::testing::PrintToString(post_order)
+        << "\n Actual END order:\n"
+        << ::testing::PrintToString(end_order);
+  }
+
+  const ::testing::AssertionResult result =
+      CheckEventOrdersForEachTask(events, task_count);
+  if (!result)
+    return result;
+
+  return CheckNoTaskRunsOverlap(events);
+}
+
+}  // namespace internal
+
+}  // namespace base