cc/scheduler/begin_frame_tracker.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 "cc/scheduler/begin_frame_tracker.h"
   6
   7 namespace cc {
   8
   9 BeginFrameTracker::BeginFrameTracker(const tracked_objects::Location& location)
  10     : location_(location),
  11       location_string_(location.ToString()),
  12       current_updated_at_(),
  13       current_args_(),
  14       current_finished_at_(base::TimeTicks::FromInternalValue(-1)) {
  15 }
  16
  17 BeginFrameTracker::~BeginFrameTracker() {
  18 }
  19
  20 void BeginFrameTracker::Start(BeginFrameArgs new_args) {
  21   // Trace the frame time being passed between BeginFrameTrackers.
  22   TRACE_EVENT_FLOW_STEP0(
  23       TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.frames"), "BeginFrameArgs",
  24       new_args.frame_time.ToInternalValue(), location_string_);
  25
  26   // Trace this specific begin frame tracker Start/Finish times.
  27   TRACE_EVENT_ASYNC_BEGIN2(
  28       TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.frames"),
  29       location_string_.c_str(), new_args.frame_time.ToInternalValue(),
  30       "new args", new_args.AsValue(), "current args", current_args_.AsValue());
  31
  32   // Check the new BeginFrameArgs are valid and monotonically increasing.
  33   DCHECK(new_args.IsValid());
  34   DCHECK_LE(current_args_.frame_time, new_args.frame_time);
  35
  36   DCHECK(HasFinished())
  37       << "Tried to start a new frame before finishing an existing frame.";
  38   current_updated_at_ = base::TimeTicks::NowFromSystemTraceTime();
  39   current_args_ = new_args;
  40   current_finished_at_ = base::TimeTicks();
  41
  42   // TODO(mithro): Add UMA tracking of delta between current_updated_at_ time
  43   // and the new_args.frame_time argument. This will give us how long after a
  44   // BeginFrameArgs message was created before we started processing it.
  45 }
  46
  47 const BeginFrameArgs& BeginFrameTracker::Current() const {
  48   DCHECK(!HasFinished())
  49       << "Tried to use BeginFrameArgs after marking the frame finished.";
  50   DCHECK(current_args_.IsValid())
  51       << "Tried to use BeginFrameArgs before starting a frame!";
  52   return current_args_;
  53 }
  54
  55 void BeginFrameTracker::Finish() {
  56   DCHECK(!HasFinished()) << "Tried to finish an already finished frame";
  57   current_finished_at_ = base::TimeTicks::NowFromSystemTraceTime();
  58   TRACE_EVENT_ASYNC_END0(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.frames"),
  59                          location_string_.c_str(),
  60                          current_args_.frame_time.ToInternalValue());
  61 }
  62
  63 const BeginFrameArgs& BeginFrameTracker::Last() const {
  64   DCHECK(current_args_.IsValid())
  65       << "Tried to use last BeginFrameArgs before starting a frame!";
  66   DCHECK(HasFinished())
  67       << "Tried to use last BeginFrameArgs before the frame is finished.";
  68   return current_args_;
  69 }
  70
  71 base::TimeDelta BeginFrameTracker::Interval() const {
  72   base::TimeDelta interval = current_args_.interval;
  73   // Normal interval will be ~16ms, 200Hz (5ms) screens are the fastest
  74   // easily available so anything less than that is likely an error.
  75   if (interval < base::TimeDelta::FromMilliseconds(1)) {
  76     interval = BeginFrameArgs::DefaultInterval();
  77   }
  78   return interval;
  79 }
  80
  81 void BeginFrameTracker::AsValueInto(
  82     base::TimeTicks now,
  83     base::trace_event::TracedValue* state) const {
  84   state->SetInteger("updated_at_us", current_updated_at_.ToInternalValue());
  85   state->SetInteger("finished_at_us", current_finished_at_.ToInternalValue());
  86   if (HasFinished()) {
  87     state->SetString("state", "FINISHED");
  88     state->BeginDictionary("current_args_");
  89   } else {
  90     state->SetString("state", "USING");
  91     state->BeginDictionary("last_args_");
  92   }
  93   current_args_.AsValueInto(state);
  94   state->EndDictionary();
  95
  96   base::TimeTicks frame_time = current_args_.frame_time;
  97   base::TimeTicks deadline = current_args_.deadline;
  98   base::TimeDelta interval = current_args_.interval;
  99   state->BeginDictionary("major_timestamps_in_ms");
 100   state->SetDouble("0_interval", interval.InMillisecondsF());
 101   state->SetDouble("1_now_to_deadline", (deadline - now).InMillisecondsF());
 102   state->SetDouble("2_frame_time_to_now", (now - frame_time).InMillisecondsF());
 103   state->SetDouble("3_frame_time_to_deadline",
 104                    (deadline - frame_time).InMillisecondsF());
 105   state->SetDouble("4_now", (now - base::TimeTicks()).InMillisecondsF());
 106   state->SetDouble("5_frame_time",
 107                    (frame_time - base::TimeTicks()).InMillisecondsF());
 108   state->SetDouble("6_deadline",
 109                    (deadline - base::TimeTicks()).InMillisecondsF());
 110   state->EndDictionary();
 111 }
 112
 113 const BeginFrameArgs& BeginFrameTracker::DangerousMethodCurrentOrLast() const {
 114   if (!HasFinished()) {
 115     return Current();
 116   } else {
 117     return Last();
 118   }
 119 }
 120
 121 }  // namespace cc