TaskScheduler: Add TRACE_TASK_EXECUTION to TaskTracker::RunTask.

base/task_scheduler/task_tracker.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 "base/callback.h"
 #include "base/debug/task_annotator.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/threading/thread_restrictions.h"
+#include "base/trace_event/trace_event.h"
 
 namespace base {
 namespace internal {
 
 namespace {
 
 const char kQueueFunctionName[] = "base::PostTask";
+const char kRunFunctionName[] = "base::RunTask";

[fdoray, 2016/05/02 19:50:08]

I don't want to call this TaskTracker::RunTask because TaskTracker is an
implementation detail of the task scheduler.

[gab, 2016/05/02 20:31:22]

Okay but base::RunTask isn't a thing... Maybe just "TaskSchedulerRunTask"? At
least not making it look like a base:: method.

[fdoray, 2016/05/03 14:06:36]

Done.

 
 // Upper bound for the
 // TaskScheduler.BlockShutdownTasksPostedDuringShutdown histogram.
 const HistogramBase::Sample kMaxBlockShutdownTasksPostedDuringShutdown = 1000;
 
 void RecordNumBlockShutdownTasksPostedDuringShutdown(
     HistogramBase::Sample value) {
   UMA_HISTOGRAM_CUSTOM_COUNTS(
       "TaskScheduler.BlockShutdownTasksPostedDuringShutdown", value, 1,
       kMaxBlockShutdownTasksPostedDuringShutdown, 50);
@@ skipping 44 matching lines @@
 }
 
 void TaskTracker::RunTask(const Task* task) {
   DCHECK(task);
 
   const TaskShutdownBehavior shutdown_behavior =
       task->traits.shutdown_behavior();
   if (!BeforeRunTask(shutdown_behavior))
     return;
 
+  TRACE_TASK_EXECUTION(kRunFunctionName, *task);

[gab, 2016/05/02 20:31:22]

https://codereview.chromium.org/1911023002/ is scoping line 94's RunTask, this
should probably go in there (or is it using a singleton and forced to be above
the SetSingletonAllowed call?)

[robliao, 2016/05/02 20:32:34]

Should this occur right after we SetSingletonAllowed?

[fdoray, 2016/05/03 14:06:36]

I initially included SetSingletonAllowed into TRACE_TASK_EXECUTION's scope
because it usually includes a little bit more than the task execution itself
[1][2][3]. Not sure we really want that though so the scope now includes the
task execution only.

[1]
https://code.google.com/p/chromium/codesearch#chromium/src/base/message_loop/...
[2]
https://code.google.com/p/chromium/codesearch#chromium/src/base/threading/wor...
[3]
https://code.google.com/p/chromium/codesearch#chromium/src/components/schedul...

+
   // All tasks run through here and the scheduler itself doesn't use singletons.
   // Therefore, it isn't necessary to reset the singleton allowed bit after
   // running the task.
   ThreadRestrictions::SetSingletonAllowed(
       task->traits.shutdown_behavior() !=
       TaskShutdownBehavior::CONTINUE_ON_SHUTDOWN);
 
   debug::TaskAnnotator task_annotator;
   task_annotator.RunTask(kQueueFunctionName, *task);
 
@@ skipping 87 matching lines @@
     AutoSchedulerLock auto_lock(lock_);
     DCHECK_GT(num_tasks_blocking_shutdown_, 0U);
     --num_tasks_blocking_shutdown_;
     if (num_tasks_blocking_shutdown_ == 0 && shutdown_cv_)
       shutdown_cv_->Signal();
   }
 }
 
 }  // namespace internal
 }  // namespace base