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_FLOW_BEGIN0(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
  24                           queue_function,
  25                           TRACE_ID_MANGLE(GetTaskTraceID(pending_task)));
  26 }
  27
  28 void TaskAnnotator::RunTask(const char* queue_function,
  29                             const char* run_function,
  30                             const PendingTask& pending_task) {
  31   tracked_objects::ThreadData::PrepareForStartOfRun(pending_task.birth_tally);
  32   tracked_objects::TaskStopwatch stopwatch;
  33   stopwatch.Start();
  34   tracked_objects::Duration queue_duration =
  35       stopwatch.StartTime() - pending_task.EffectiveTimePosted();
  36
  37   TRACE_EVENT_FLOW_END1(TRACE_DISABLED_BY_DEFAULT("toplevel.flow"),
  38                         queue_function,
  39                         TRACE_ID_MANGLE(GetTaskTraceID(pending_task)),
  40                         "queue_duration",
  41                         queue_duration.InMilliseconds());
  42
  43   // When tracing memory for posted tasks it's more valuable to attribute the
  44   // memory allocations to the source function than generically to the task
  45   // runner.
  46   TRACE_EVENT_WITH_MEMORY_TAG2(
  47       "toplevel",
  48       run_function,
  49       pending_task.posted_from.function_name(),  // Name for memory tracking.
  50       "src_file",
  51       pending_task.posted_from.file_name(),
  52       "src_func",
  53       pending_task.posted_from.function_name());
  54
  55   // Before running the task, store the program counter where it was posted
  56   // and deliberately alias it to ensure it is on the stack if the task
  57   // crashes. Be careful not to assume that the variable itself will have the
  58   // expected value when displayed by the optimizer in an optimized build.
  59   // Look at a memory dump of the stack.
  60   const void* program_counter = pending_task.posted_from.program_counter();
  61   debug::Alias(&program_counter);
  62
  63   pending_task.task.Run();
  64
  65   stopwatch.Stop();
  66   tracked_objects::ThreadData::TallyRunOnNamedThreadIfTracking(
  67       pending_task, stopwatch);
  68 }
  69
  70 uint64 TaskAnnotator::GetTaskTraceID(const PendingTask& task) const {
  71   return (static_cast<uint64>(task.sequence_num) << 32) |
  72          ((static_cast<uint64>(reinterpret_cast<intptr_t>(this)) << 32) >> 32);
  73 }
  74
  75 }  // namespace debug
  76 }  // namespace base