base/debug/task_annotator.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/debug/task_annotator.h"
   6
   7 #include "base/debug/alias.h"
   8 #include "base/pending_task.h"
   9 #include "base/trace_event/trace_event.h"
  10 #include "base/tracked_objects.h"
  11
  12 namespace base {
  13 namespace debug {
  14
  15 TaskAnnotator::TaskAnnotator() {
  16 }
  17
  18 TaskAnnotator::~TaskAnnotator() {
  19 }
  20
  21 void TaskAnnotator::DidQueueTask(const char* queue_function,
  22                                  const PendingTask& pending_task) {
  23   TRACE_EVENT_WITH_FLOW0(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
  24                           queue_function,
  25                           TRACE_ID_MANGLE(GetTaskTraceID(pending_task)),
  26                           TRACE_EVENT_FLAG_FLOW_OUT);
  27 }
  28
  29 void TaskAnnotator::RunTask(const char* queue_function,
  30                             const PendingTask& pending_task) {
  31   tracked_objects::TaskStopwatch stopwatch;
  32   stopwatch.Start();
  33   tracked_objects::Duration queue_duration =
  34       stopwatch.StartTime() - pending_task.EffectiveTimePosted();
  35
  36   TRACE_EVENT_WITH_FLOW1(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
  37                           queue_function,
  38                           TRACE_ID_MANGLE(GetTaskTraceID(pending_task)),
  39                           TRACE_EVENT_FLAG_FLOW_IN,
  40                           "queue_duration",
  41                           queue_duration.InMilliseconds());
  42
  43   // Before running the task, store the program counter where it was posted
  44   // and deliberately alias it to ensure it is on the stack if the task
  45   // crashes. Be careful not to assume that the variable itself will have the
  46   // expected value when displayed by the optimizer in an optimized build.
  47   // Look at a memory dump of the stack.
  48   const void* program_counter = pending_task.posted_from.program_counter();
  49   debug::Alias(&program_counter);
  50
  51   pending_task.task.Run();
  52
  53   stopwatch.Stop();
  54   tracked_objects::ThreadData::TallyRunOnNamedThreadIfTracking(
  55       pending_task, stopwatch);
  56 }
  57
  58 uint64 TaskAnnotator::GetTaskTraceID(const PendingTask& task) const {
  59   return (static_cast<uint64>(task.sequence_num) << 32) |
  60          ((static_cast<uint64>(reinterpret_cast<intptr_t>(this)) << 32) >> 32);
  61 }
  62
  63 }  // namespace debug
  64 }  // namespace base