cc/scheduler/scheduler.cc

   1 // Copyright 2011 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/scheduler.h"
   6
   7 #include <algorithm>
   8
   9 #include "base/auto_reset.h"
  10 #include "base/logging.h"
  11 #include "base/profiler/scoped_tracker.h"
  12 #include "base/single_thread_task_runner.h"
  13 #include "base/trace_event/trace_event.h"
  14 #include "base/trace_event/trace_event_argument.h"
  15 #include "cc/debug/devtools_instrumentation.h"
  16 #include "cc/debug/traced_value.h"
  17 #include "cc/scheduler/delay_based_time_source.h"
  18 #include "ui/gfx/frame_time.h"
  19
  20 namespace cc {
  21
  22 BeginFrameSource* SchedulerFrameSourcesConstructor::ConstructPrimaryFrameSource(
  23     Scheduler* scheduler) {
  24   if (scheduler->settings_.use_external_begin_frame_source) {
  25     TRACE_EVENT1("cc",
  26                  "Scheduler::Scheduler()",
  27                  "PrimaryFrameSource",
  28                  "ExternalBeginFrameSource");
  29     DCHECK(scheduler->primary_frame_source_internal_)
  30         << "Need external BeginFrameSource";
  31     return scheduler->primary_frame_source_internal_.get();
  32   } else {
  33     TRACE_EVENT1("cc",
  34                  "Scheduler::Scheduler()",
  35                  "PrimaryFrameSource",
  36                  "SyntheticBeginFrameSource");
  37     scoped_ptr<SyntheticBeginFrameSource> synthetic_source =
  38         SyntheticBeginFrameSource::Create(scheduler->task_runner_.get(),
  39                                           scheduler->Now(),
  40                                           BeginFrameArgs::DefaultInterval());
  41
  42     DCHECK(!scheduler->vsync_observer_);
  43     scheduler->vsync_observer_ = synthetic_source.get();
  44
  45     DCHECK(!scheduler->primary_frame_source_internal_);
  46     scheduler->primary_frame_source_internal_ = synthetic_source.Pass();
  47     return scheduler->primary_frame_source_internal_.get();
  48   }
  49 }
  50
  51 BeginFrameSource*
  52 SchedulerFrameSourcesConstructor::ConstructBackgroundFrameSource(
  53     Scheduler* scheduler) {
  54   TRACE_EVENT1("cc",
  55                "Scheduler::Scheduler()",
  56                "BackgroundFrameSource",
  57                "SyntheticBeginFrameSource");
  58   DCHECK(!(scheduler->background_frame_source_internal_));
  59   scheduler->background_frame_source_internal_ =
  60       SyntheticBeginFrameSource::Create(
  61           scheduler->task_runner_.get(), scheduler->Now(),
  62           scheduler->settings_.background_frame_interval);
  63   return scheduler->background_frame_source_internal_.get();
  64 }
  65
  66 BeginFrameSource*
  67 SchedulerFrameSourcesConstructor::ConstructUnthrottledFrameSource(
  68     Scheduler* scheduler) {
  69   TRACE_EVENT1("cc", "Scheduler::Scheduler()", "UnthrottledFrameSource",
  70                "BackToBackBeginFrameSource");
  71   DCHECK(!scheduler->unthrottled_frame_source_internal_);
  72   scheduler->unthrottled_frame_source_internal_ =
  73       BackToBackBeginFrameSource::Create(scheduler->task_runner_.get());
  74   return scheduler->unthrottled_frame_source_internal_.get();
  75 }
  76
  77 Scheduler::Scheduler(
  78     SchedulerClient* client,
  79     const SchedulerSettings& scheduler_settings,
  80     int layer_tree_host_id,
  81     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner,
  82     scoped_ptr<BeginFrameSource> external_begin_frame_source,
  83     SchedulerFrameSourcesConstructor* frame_sources_constructor)
  84     : frame_source_(),
  85       primary_frame_source_(NULL),
  86       background_frame_source_(NULL),
  87       primary_frame_source_internal_(external_begin_frame_source.Pass()),
  88       background_frame_source_internal_(),
  89       vsync_observer_(NULL),
  90       authoritative_vsync_interval_(base::TimeDelta()),
  91       last_vsync_timebase_(base::TimeTicks()),
  92       throttle_frame_production_(scheduler_settings.throttle_frame_production),
  93       settings_(scheduler_settings),
  94       client_(client),
  95       layer_tree_host_id_(layer_tree_host_id),
  96       task_runner_(task_runner),
  97       state_machine_(scheduler_settings),
  98       inside_process_scheduled_actions_(false),
  99       inside_action_(SchedulerStateMachine::ACTION_NONE),
 100       weak_factory_(this) {
 101   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 102                "Scheduler::Scheduler",
 103                "settings",
 104                settings_.AsValue());
 105   DCHECK(client_);
 106   DCHECK(!state_machine_.BeginFrameNeeded());
 107
 108   begin_retro_frame_closure_ =
 109       base::Bind(&Scheduler::BeginRetroFrame, weak_factory_.GetWeakPtr());
 110   begin_impl_frame_deadline_closure_ = base::Bind(
 111       &Scheduler::OnBeginImplFrameDeadline, weak_factory_.GetWeakPtr());
 112   poll_for_draw_triggers_closure_ = base::Bind(
 113       &Scheduler::PollForAnticipatedDrawTriggers, weak_factory_.GetWeakPtr());
 114   advance_commit_state_closure_ = base::Bind(
 115       &Scheduler::PollToAdvanceCommitState, weak_factory_.GetWeakPtr());
 116
 117   frame_source_ = BeginFrameSourceMultiplexer::Create();
 118   frame_source_->AddObserver(this);
 119
 120   // Primary frame source
 121   primary_frame_source_ =
 122       frame_sources_constructor->ConstructPrimaryFrameSource(this);
 123   frame_source_->AddSource(primary_frame_source_);
 124   primary_frame_source_->SetClientReady();
 125
 126   // Background ticking frame source
 127   background_frame_source_ =
 128       frame_sources_constructor->ConstructBackgroundFrameSource(this);
 129   frame_source_->AddSource(background_frame_source_);
 130
 131   // Unthrottled frame source
 132   unthrottled_frame_source_ =
 133       frame_sources_constructor->ConstructUnthrottledFrameSource(this);
 134   frame_source_->AddSource(unthrottled_frame_source_);
 135 }
 136
 137 Scheduler::~Scheduler() {
 138   if (frame_source_->NeedsBeginFrames())
 139     frame_source_->SetNeedsBeginFrames(false);
 140 }
 141
 142 base::TimeTicks Scheduler::Now() const {
 143   base::TimeTicks now = gfx::FrameTime::Now();
 144   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.now"),
 145                "Scheduler::Now",
 146                "now",
 147                now);
 148   return now;
 149 }
 150
 151 void Scheduler::CommitVSyncParameters(base::TimeTicks timebase,
 152                                       base::TimeDelta interval) {
 153   if (authoritative_vsync_interval_ != base::TimeDelta()) {
 154     interval = authoritative_vsync_interval_;
 155   } else if (interval == base::TimeDelta()) {
 156     // TODO(brianderson): We should not be receiving 0 intervals.
 157     interval = BeginFrameArgs::DefaultInterval();
 158   }
 159
 160   last_vsync_timebase_ = timebase;
 161
 162   if (vsync_observer_)
 163     vsync_observer_->OnUpdateVSyncParameters(timebase, interval);
 164 }
 165
 166 void Scheduler::SetEstimatedParentDrawTime(base::TimeDelta draw_time) {
 167   DCHECK_GE(draw_time.ToInternalValue(), 0);
 168   estimated_parent_draw_time_ = draw_time;
 169 }
 170
 171 void Scheduler::SetCanStart() {
 172   state_machine_.SetCanStart();
 173   ProcessScheduledActions();
 174 }
 175
 176 void Scheduler::UpdateActiveFrameSource() {
 177   if (state_machine_.visible()) {
 178     if (throttle_frame_production_) {
 179       frame_source_->SetActiveSource(primary_frame_source_);
 180     } else {
 181       frame_source_->SetActiveSource(unthrottled_frame_source_);
 182     }
 183   } else {
 184     frame_source_->SetActiveSource(background_frame_source_);
 185   }
 186   ProcessScheduledActions();
 187 }
 188
 189 void Scheduler::SetVisible(bool visible) {
 190   state_machine_.SetVisible(visible);
 191   UpdateActiveFrameSource();
 192 }
 193
 194 void Scheduler::SetCanDraw(bool can_draw) {
 195   state_machine_.SetCanDraw(can_draw);
 196   ProcessScheduledActions();
 197 }
 198
 199 void Scheduler::NotifyReadyToActivate() {
 200   state_machine_.NotifyReadyToActivate();
 201   ProcessScheduledActions();
 202 }
 203
 204 void Scheduler::NotifyReadyToDraw() {
 205   // Empty for now, until we take action based on the notification as part of
 206   // crbugs 352894, 383157, 421923.
 207 }
 208
 209 void Scheduler::SetThrottleFrameProduction(bool throttle) {
 210   throttle_frame_production_ = throttle;
 211   UpdateActiveFrameSource();
 212 }
 213
 214 void Scheduler::SetNeedsCommit() {
 215   state_machine_.SetNeedsCommit();
 216   ProcessScheduledActions();
 217 }
 218
 219 void Scheduler::SetNeedsRedraw() {
 220   state_machine_.SetNeedsRedraw();
 221   ProcessScheduledActions();
 222 }
 223
 224 void Scheduler::SetNeedsAnimate() {
 225   state_machine_.SetNeedsAnimate();
 226   ProcessScheduledActions();
 227 }
 228
 229 void Scheduler::SetNeedsPrepareTiles() {
 230   DCHECK(!IsInsideAction(SchedulerStateMachine::ACTION_PREPARE_TILES));
 231   state_machine_.SetNeedsPrepareTiles();
 232   ProcessScheduledActions();
 233 }
 234
 235 void Scheduler::SetMaxSwapsPending(int max) {
 236   state_machine_.SetMaxSwapsPending(max);
 237 }
 238
 239 void Scheduler::DidSwapBuffers() {
 240   state_machine_.DidSwapBuffers();
 241
 242   // There is no need to call ProcessScheduledActions here because
 243   // swapping should not trigger any new actions.
 244   if (!inside_process_scheduled_actions_) {
 245     DCHECK_EQ(state_machine_.NextAction(), SchedulerStateMachine::ACTION_NONE);
 246   }
 247 }
 248
 249 void Scheduler::DidSwapBuffersComplete() {
 250   state_machine_.DidSwapBuffersComplete();
 251   ProcessScheduledActions();
 252 }
 253
 254 void Scheduler::SetImplLatencyTakesPriority(bool impl_latency_takes_priority) {
 255   state_machine_.SetImplLatencyTakesPriority(impl_latency_takes_priority);
 256   ProcessScheduledActions();
 257 }
 258
 259 void Scheduler::NotifyReadyToCommit() {
 260   TRACE_EVENT0("cc", "Scheduler::NotifyReadyToCommit");
 261   state_machine_.NotifyReadyToCommit();
 262   ProcessScheduledActions();
 263 }
 264
 265 void Scheduler::BeginMainFrameAborted(CommitEarlyOutReason reason) {
 266   TRACE_EVENT1("cc", "Scheduler::BeginMainFrameAborted", "reason",
 267                CommitEarlyOutReasonToString(reason));
 268   state_machine_.BeginMainFrameAborted(reason);
 269   ProcessScheduledActions();
 270 }
 271
 272 void Scheduler::DidPrepareTiles() {
 273   state_machine_.DidPrepareTiles();
 274 }
 275
 276 void Scheduler::DidLoseOutputSurface() {
 277   TRACE_EVENT0("cc", "Scheduler::DidLoseOutputSurface");
 278   begin_retro_frame_args_.clear();
 279   begin_retro_frame_task_.Cancel();
 280   state_machine_.DidLoseOutputSurface();
 281   ProcessScheduledActions();
 282 }
 283
 284 void Scheduler::DidCreateAndInitializeOutputSurface() {
 285   TRACE_EVENT0("cc", "Scheduler::DidCreateAndInitializeOutputSurface");
 286   DCHECK(!frame_source_->NeedsBeginFrames());
 287   DCHECK(begin_impl_frame_deadline_task_.IsCancelled());
 288   state_machine_.DidCreateAndInitializeOutputSurface();
 289   ProcessScheduledActions();
 290 }
 291
 292 void Scheduler::NotifyBeginMainFrameStarted() {
 293   TRACE_EVENT0("cc", "Scheduler::NotifyBeginMainFrameStarted");
 294   state_machine_.NotifyBeginMainFrameStarted();
 295 }
 296
 297 base::TimeTicks Scheduler::AnticipatedDrawTime() const {
 298   if (!frame_source_->NeedsBeginFrames() ||
 299       begin_impl_frame_args_.interval <= base::TimeDelta())
 300     return base::TimeTicks();
 301
 302   base::TimeTicks now = Now();
 303   base::TimeTicks timebase = std::max(begin_impl_frame_args_.frame_time,
 304                                       begin_impl_frame_args_.deadline);
 305   int64 intervals = 1 + ((now - timebase) / begin_impl_frame_args_.interval);
 306   return timebase + (begin_impl_frame_args_.interval * intervals);
 307 }
 308
 309 base::TimeTicks Scheduler::LastBeginImplFrameTime() {
 310   return begin_impl_frame_args_.frame_time;
 311 }
 312
 313 void Scheduler::SetupNextBeginFrameIfNeeded() {
 314   // Never call SetNeedsBeginFrames if the frame source already has the right
 315   // value.
 316   if (frame_source_->NeedsBeginFrames() != state_machine_.BeginFrameNeeded()) {
 317     if (state_machine_.BeginFrameNeeded()) {
 318       // Call SetNeedsBeginFrames(true) as soon as possible.
 319       frame_source_->SetNeedsBeginFrames(true);
 320     } else if (state_machine_.begin_impl_frame_state() ==
 321                SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE) {
 322       // Call SetNeedsBeginFrames(false) in between frames only.
 323       frame_source_->SetNeedsBeginFrames(false);
 324       client_->SendBeginMainFrameNotExpectedSoon();
 325     }
 326   }
 327
 328   PostBeginRetroFrameIfNeeded();
 329 }
 330
 331 // We may need to poll when we can't rely on BeginFrame to advance certain
 332 // state or to avoid deadlock.
 333 void Scheduler::SetupPollingMechanisms() {
 334   bool needs_advance_commit_state_timer = false;
 335   // Setup PollForAnticipatedDrawTriggers if we need to monitor state but
 336   // aren't expecting any more BeginFrames. This should only be needed by
 337   // the synchronous compositor when BeginFrameNeeded is false.
 338   if (state_machine_.ShouldPollForAnticipatedDrawTriggers()) {
 339     DCHECK(!state_machine_.SupportsProactiveBeginFrame());
 340     if (poll_for_draw_triggers_task_.IsCancelled()) {
 341       poll_for_draw_triggers_task_.Reset(poll_for_draw_triggers_closure_);
 342       base::TimeDelta delay = begin_impl_frame_args_.IsValid()
 343                                   ? begin_impl_frame_args_.interval
 344                                   : BeginFrameArgs::DefaultInterval();
 345       task_runner_->PostDelayedTask(
 346           FROM_HERE, poll_for_draw_triggers_task_.callback(), delay);
 347     }
 348   } else {
 349     poll_for_draw_triggers_task_.Cancel();
 350
 351     // At this point we'd prefer to advance through the commit flow by
 352     // drawing a frame, however it's possible that the frame rate controller
 353     // will not give us a BeginFrame until the commit completes.  See
 354     // crbug.com/317430 for an example of a swap ack being held on commit. Thus
 355     // we set a repeating timer to poll on ProcessScheduledActions until we
 356     // successfully reach BeginFrame. Synchronous compositor does not use
 357     // frame rate controller or have the circular wait in the bug.
 358     if (IsBeginMainFrameSentOrStarted() &&
 359         !settings_.using_synchronous_renderer_compositor) {
 360       needs_advance_commit_state_timer = true;
 361     }
 362   }
 363
 364   if (needs_advance_commit_state_timer) {
 365     if (advance_commit_state_task_.IsCancelled() &&
 366         begin_impl_frame_args_.IsValid()) {
 367       // Since we'd rather get a BeginImplFrame by the normal mechanism, we
 368       // set the interval to twice the interval from the previous frame.
 369       advance_commit_state_task_.Reset(advance_commit_state_closure_);
 370       task_runner_->PostDelayedTask(FROM_HERE,
 371                                     advance_commit_state_task_.callback(),
 372                                     begin_impl_frame_args_.interval * 2);
 373     }
 374   } else {
 375     advance_commit_state_task_.Cancel();
 376   }
 377 }
 378
 379 // BeginFrame is the mechanism that tells us that now is a good time to start
 380 // making a frame. Usually this means that user input for the frame is complete.
 381 // If the scheduler is busy, we queue the BeginFrame to be handled later as
 382 // a BeginRetroFrame.
 383 bool Scheduler::OnBeginFrameMixInDelegate(const BeginFrameArgs& args) {
 384   TRACE_EVENT1("cc,benchmark", "Scheduler::BeginFrame", "args", args.AsValue());
 385
 386   // Deliver BeginFrames to children.
 387   if (state_machine_.children_need_begin_frames()) {
 388     BeginFrameArgs adjusted_args_for_children(args);
 389     // Adjust a deadline for child schedulers.
 390     // TODO(simonhong): Once we have commitless update, we can get rid of
 391     // BeginMainFrameToCommitDurationEstimate() +
 392     // CommitToActivateDurationEstimate().
 393     adjusted_args_for_children.deadline -=
 394         (client_->BeginMainFrameToCommitDurationEstimate() +
 395          client_->CommitToActivateDurationEstimate() +
 396          client_->DrawDurationEstimate() + EstimatedParentDrawTime());
 397     client_->SendBeginFramesToChildren(adjusted_args_for_children);
 398   }
 399
 400   BeginFrameArgs adjusted_args(args);
 401   adjusted_args.deadline -= EstimatedParentDrawTime();
 402
 403   // We have just called SetNeedsBeginFrame(true) and the BeginFrameSource has
 404   // sent us the last BeginFrame we have missed. As we might not be able to
 405   // actually make rendering for this call, handle it like a "retro frame".
 406   // TODO(brainderson): Add a test for this functionality ASAP!
 407   if (adjusted_args.type == BeginFrameArgs::MISSED) {
 408     begin_retro_frame_args_.push_back(adjusted_args);
 409     PostBeginRetroFrameIfNeeded();
 410     return true;
 411   }
 412
 413   bool should_defer_begin_frame;
 414   if (settings_.using_synchronous_renderer_compositor) {
 415     should_defer_begin_frame = false;
 416   } else {
 417     should_defer_begin_frame =
 418         !begin_retro_frame_args_.empty() ||
 419         !begin_retro_frame_task_.IsCancelled() ||
 420         !frame_source_->NeedsBeginFrames() ||
 421         (state_machine_.begin_impl_frame_state() !=
 422          SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 423   }
 424
 425   if (should_defer_begin_frame) {
 426     begin_retro_frame_args_.push_back(adjusted_args);
 427     TRACE_EVENT_INSTANT0(
 428         "cc", "Scheduler::BeginFrame deferred", TRACE_EVENT_SCOPE_THREAD);
 429     // Queuing the frame counts as "using it", so we need to return true.
 430   } else {
 431     BeginImplFrame(adjusted_args);
 432   }
 433   return true;
 434 }
 435
 436 void Scheduler::SetChildrenNeedBeginFrames(bool children_need_begin_frames) {
 437   state_machine_.SetChildrenNeedBeginFrames(children_need_begin_frames);
 438   ProcessScheduledActions();
 439 }
 440
 441 void Scheduler::SetAuthoritativeVSyncInterval(const base::TimeDelta& interval) {
 442   authoritative_vsync_interval_ = interval;
 443   if (vsync_observer_)
 444     vsync_observer_->OnUpdateVSyncParameters(last_vsync_timebase_, interval);
 445 }
 446
 447 // BeginRetroFrame is called for BeginFrames that we've deferred because
 448 // the scheduler was in the middle of processing a previous BeginFrame.
 449 void Scheduler::BeginRetroFrame() {
 450   TRACE_EVENT0("cc,benchmark", "Scheduler::BeginRetroFrame");
 451   DCHECK(!settings_.using_synchronous_renderer_compositor);
 452   DCHECK(!begin_retro_frame_args_.empty());
 453   DCHECK(!begin_retro_frame_task_.IsCancelled());
 454   DCHECK_EQ(state_machine_.begin_impl_frame_state(),
 455             SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 456
 457   begin_retro_frame_task_.Cancel();
 458
 459   // Discard expired BeginRetroFrames
 460   // Today, we should always end up with at most one un-expired BeginRetroFrame
 461   // because deadlines will not be greater than the next frame time. We don't
 462   // DCHECK though because some systems don't always have monotonic timestamps.
 463   // TODO(brianderson): In the future, long deadlines could result in us not
 464   // draining the queue if we don't catch up. If we consistently can't catch
 465   // up, our fallback should be to lower our frame rate.
 466   base::TimeTicks now = Now();
 467
 468   while (!begin_retro_frame_args_.empty()) {
 469     const BeginFrameArgs& args = begin_retro_frame_args_.front();
 470     base::TimeTicks expiration_time = args.frame_time + args.interval;
 471     if (now <= expiration_time)
 472       break;
 473     TRACE_EVENT_INSTANT2(
 474         "cc", "Scheduler::BeginRetroFrame discarding", TRACE_EVENT_SCOPE_THREAD,
 475         "expiration_time - now", (expiration_time - now).InMillisecondsF(),
 476         "BeginFrameArgs", begin_retro_frame_args_.front().AsValue());
 477     begin_retro_frame_args_.pop_front();
 478     frame_source_->DidFinishFrame(begin_retro_frame_args_.size());
 479   }
 480
 481   if (begin_retro_frame_args_.empty()) {
 482     TRACE_EVENT_INSTANT0("cc",
 483                          "Scheduler::BeginRetroFrames all expired",
 484                          TRACE_EVENT_SCOPE_THREAD);
 485   } else {
 486     BeginFrameArgs front = begin_retro_frame_args_.front();
 487     begin_retro_frame_args_.pop_front();
 488     BeginImplFrame(front);
 489   }
 490 }
 491
 492 // There could be a race between the posted BeginRetroFrame and a new
 493 // BeginFrame arriving via the normal mechanism. Scheduler::BeginFrame
 494 // will check if there is a pending BeginRetroFrame to ensure we handle
 495 // BeginFrames in FIFO order.
 496 void Scheduler::PostBeginRetroFrameIfNeeded() {
 497   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 498                "Scheduler::PostBeginRetroFrameIfNeeded",
 499                "state",
 500                AsValue());
 501   if (!frame_source_->NeedsBeginFrames())
 502     return;
 503
 504   if (begin_retro_frame_args_.empty() || !begin_retro_frame_task_.IsCancelled())
 505     return;
 506
 507   // begin_retro_frame_args_ should always be empty for the
 508   // synchronous compositor.
 509   DCHECK(!settings_.using_synchronous_renderer_compositor);
 510
 511   if (state_machine_.begin_impl_frame_state() !=
 512       SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE)
 513     return;
 514
 515   begin_retro_frame_task_.Reset(begin_retro_frame_closure_);
 516
 517   task_runner_->PostTask(FROM_HERE, begin_retro_frame_task_.callback());
 518 }
 519
 520 // BeginImplFrame starts a compositor frame that will wait up until a deadline
 521 // for a BeginMainFrame+activation to complete before it times out and draws
 522 // any asynchronous animation and scroll/pinch updates.
 523 void Scheduler::BeginImplFrame(const BeginFrameArgs& args) {
 524   bool main_thread_is_in_high_latency_mode =
 525       state_machine_.MainThreadIsInHighLatencyMode();
 526   TRACE_EVENT2("cc,benchmark",
 527                "Scheduler::BeginImplFrame",
 528                "args",
 529                args.AsValue(),
 530                "main_thread_is_high_latency",
 531                main_thread_is_in_high_latency_mode);
 532   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 533                  "MainThreadLatency",
 534                  main_thread_is_in_high_latency_mode);
 535   DCHECK_EQ(state_machine_.begin_impl_frame_state(),
 536             SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 537   DCHECK(state_machine_.HasInitializedOutputSurface());
 538
 539   advance_commit_state_task_.Cancel();
 540
 541   begin_impl_frame_args_ = args;
 542   begin_impl_frame_args_.deadline -= client_->DrawDurationEstimate();
 543
 544   if (!state_machine_.impl_latency_takes_priority() &&
 545       main_thread_is_in_high_latency_mode &&
 546       CanCommitAndActivateBeforeDeadline()) {
 547     state_machine_.SetSkipNextBeginMainFrameToReduceLatency();
 548   }
 549
 550   state_machine_.OnBeginImplFrame();
 551   devtools_instrumentation::DidBeginFrame(layer_tree_host_id_);
 552   client_->WillBeginImplFrame(begin_impl_frame_args_);
 553
 554   ProcessScheduledActions();
 555
 556   state_machine_.OnBeginImplFrameDeadlinePending();
 557
 558   if (settings_.using_synchronous_renderer_compositor) {
 559     // The synchronous renderer compositor has to make its GL calls
 560     // within this call.
 561     // TODO(brianderson): Have the OutputSurface initiate the deadline tasks
 562     // so the synchronous renderer compositor can take advantage of splitting
 563     // up the BeginImplFrame and deadline as well.
 564     OnBeginImplFrameDeadline();
 565   } else {
 566     ScheduleBeginImplFrameDeadline();
 567   }
 568 }
 569
 570 void Scheduler::ScheduleBeginImplFrameDeadline() {
 571   // The synchronous compositor does not post a deadline task.
 572   DCHECK(!settings_.using_synchronous_renderer_compositor);
 573
 574   begin_impl_frame_deadline_task_.Cancel();
 575   begin_impl_frame_deadline_task_.Reset(begin_impl_frame_deadline_closure_);
 576
 577   begin_impl_frame_deadline_mode_ =
 578       state_machine_.CurrentBeginImplFrameDeadlineMode();
 579
 580   base::TimeTicks deadline;
 581   switch (begin_impl_frame_deadline_mode_) {
 582     case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE:
 583       // We are ready to draw a new active tree immediately.
 584       // We don't use Now() here because it's somewhat expensive to call.
 585       deadline = base::TimeTicks();
 586       break;
 587     case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR:
 588       // We are animating on the impl thread but we can wait for some time.
 589       deadline = begin_impl_frame_args_.deadline;
 590       break;
 591     case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE:
 592       // We are blocked for one reason or another and we should wait.
 593       // TODO(brianderson): Handle long deadlines (that are past the next
 594       // frame's frame time) properly instead of using this hack.
 595       deadline =
 596           begin_impl_frame_args_.frame_time + begin_impl_frame_args_.interval;
 597       break;
 598   }
 599
 600   TRACE_EVENT1(
 601       "cc", "Scheduler::ScheduleBeginImplFrameDeadline", "deadline", deadline);
 602
 603   base::TimeDelta delta = deadline - Now();
 604   if (delta <= base::TimeDelta())
 605     delta = base::TimeDelta();
 606   task_runner_->PostDelayedTask(
 607       FROM_HERE, begin_impl_frame_deadline_task_.callback(), delta);
 608 }
 609
 610 void Scheduler::RescheduleBeginImplFrameDeadlineIfNeeded() {
 611   if (settings_.using_synchronous_renderer_compositor)
 612     return;
 613
 614   if (state_machine_.begin_impl_frame_state() !=
 615       SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME)
 616     return;
 617
 618   if (begin_impl_frame_deadline_mode_ !=
 619       state_machine_.CurrentBeginImplFrameDeadlineMode())
 620     ScheduleBeginImplFrameDeadline();
 621 }
 622
 623 void Scheduler::OnBeginImplFrameDeadline() {
 624   TRACE_EVENT0("cc,benchmark", "Scheduler::OnBeginImplFrameDeadline");
 625   begin_impl_frame_deadline_task_.Cancel();
 626   // We split the deadline actions up into two phases so the state machine
 627   // has a chance to trigger actions that should occur durring and after
 628   // the deadline separately. For example:
 629   // * Sending the BeginMainFrame will not occur after the deadline in
 630   //     order to wait for more user-input before starting the next commit.
 631   // * Creating a new OuputSurface will not occur during the deadline in
 632   //     order to allow the state machine to "settle" first.
 633
 634   // TODO(robliao): Remove ScopedTracker below once crbug.com/461509 is fixed.
 635   tracked_objects::ScopedTracker tracking_profile1(
 636       FROM_HERE_WITH_EXPLICIT_FUNCTION(
 637           "461509 Scheduler::OnBeginImplFrameDeadline1"));
 638   state_machine_.OnBeginImplFrameDeadline();
 639   ProcessScheduledActions();
 640   state_machine_.OnBeginImplFrameIdle();
 641   ProcessScheduledActions();
 642
 643   client_->DidBeginImplFrameDeadline();
 644   frame_source_->DidFinishFrame(begin_retro_frame_args_.size());
 645 }
 646
 647 void Scheduler::PollForAnticipatedDrawTriggers() {
 648   TRACE_EVENT0("cc", "Scheduler::PollForAnticipatedDrawTriggers");
 649   poll_for_draw_triggers_task_.Cancel();
 650   state_machine_.DidEnterPollForAnticipatedDrawTriggers();
 651   ProcessScheduledActions();
 652   state_machine_.DidLeavePollForAnticipatedDrawTriggers();
 653 }
 654
 655 void Scheduler::PollToAdvanceCommitState() {
 656   TRACE_EVENT0("cc", "Scheduler::PollToAdvanceCommitState");
 657   advance_commit_state_task_.Cancel();
 658   ProcessScheduledActions();
 659 }
 660
 661 void Scheduler::DrawAndSwapIfPossible() {
 662   DrawResult result = client_->ScheduledActionDrawAndSwapIfPossible();
 663   state_machine_.DidDrawIfPossibleCompleted(result);
 664 }
 665
 666 void Scheduler::SetDeferCommits(bool defer_commits) {
 667   TRACE_EVENT1("cc", "Scheduler::SetDeferCommits",
 668                 "defer_commits",
 669                 defer_commits);
 670   state_machine_.SetDeferCommits(defer_commits);
 671   ProcessScheduledActions();
 672 }
 673
 674 void Scheduler::ProcessScheduledActions() {
 675   // We do not allow ProcessScheduledActions to be recursive.
 676   // The top-level call will iteratively execute the next action for us anyway.
 677   if (inside_process_scheduled_actions_)
 678     return;
 679
 680   base::AutoReset<bool> mark_inside(&inside_process_scheduled_actions_, true);
 681
 682   SchedulerStateMachine::Action action;
 683   do {
 684     action = state_machine_.NextAction();
 685     TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 686                  "SchedulerStateMachine",
 687                  "state",
 688                  AsValue());
 689     VLOG(2) << "Scheduler::ProcessScheduledActions: "
 690             << SchedulerStateMachine::ActionToString(action) << " "
 691             << state_machine_.GetStatesForDebugging();
 692     state_machine_.UpdateState(action);
 693     base::AutoReset<SchedulerStateMachine::Action>
 694         mark_inside_action(&inside_action_, action);
 695     switch (action) {
 696       case SchedulerStateMachine::ACTION_NONE:
 697         break;
 698       case SchedulerStateMachine::ACTION_ANIMATE:
 699         client_->ScheduledActionAnimate();
 700         break;
 701       case SchedulerStateMachine::ACTION_SEND_BEGIN_MAIN_FRAME:
 702         client_->ScheduledActionSendBeginMainFrame();
 703         break;
 704       case SchedulerStateMachine::ACTION_COMMIT: {
 705         // TODO(robliao): Remove ScopedTracker below once crbug.com/461509 is
 706         // fixed.
 707         tracked_objects::ScopedTracker tracking_profile4(
 708             FROM_HERE_WITH_EXPLICIT_FUNCTION(
 709                 "461509 Scheduler::ProcessScheduledActions4"));
 710         client_->ScheduledActionCommit();
 711         break;
 712       }
 713       case SchedulerStateMachine::ACTION_ACTIVATE_SYNC_TREE:
 714         client_->ScheduledActionActivateSyncTree();
 715         break;
 716       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_IF_POSSIBLE: {
 717         // TODO(robliao): Remove ScopedTracker below once crbug.com/461509 is
 718         // fixed.
 719         tracked_objects::ScopedTracker tracking_profile6(
 720             FROM_HERE_WITH_EXPLICIT_FUNCTION(
 721                 "461509 Scheduler::ProcessScheduledActions6"));
 722         DrawAndSwapIfPossible();
 723         break;
 724       }
 725       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_FORCED:
 726         client_->ScheduledActionDrawAndSwapForced();
 727         break;
 728       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_ABORT:
 729         // No action is actually performed, but this allows the state machine to
 730         // advance out of its waiting to draw state without actually drawing.
 731         break;
 732       case SchedulerStateMachine::ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
 733         client_->ScheduledActionBeginOutputSurfaceCreation();
 734         break;
 735       case SchedulerStateMachine::ACTION_PREPARE_TILES:
 736         client_->ScheduledActionPrepareTiles();
 737         break;
 738     }
 739   } while (action != SchedulerStateMachine::ACTION_NONE);
 740
 741   SetupPollingMechanisms();
 742
 743   client_->DidAnticipatedDrawTimeChange(AnticipatedDrawTime());
 744
 745   RescheduleBeginImplFrameDeadlineIfNeeded();
 746
 747   SetupNextBeginFrameIfNeeded();
 748 }
 749
 750 scoped_refptr<base::trace_event::ConvertableToTraceFormat> Scheduler::AsValue()
 751     const {
 752   scoped_refptr<base::trace_event::TracedValue> state =
 753       new base::trace_event::TracedValue();
 754   AsValueInto(state.get());
 755   return state;
 756 }
 757
 758 void Scheduler::AsValueInto(base::trace_event::TracedValue* state) const {
 759   state->BeginDictionary("state_machine");
 760   state_machine_.AsValueInto(state);
 761   state->EndDictionary();
 762
 763   // Only trace frame sources when explicitly enabled - http://crbug.com/420607
 764   bool frame_tracing_enabled = false;
 765   TRACE_EVENT_CATEGORY_GROUP_ENABLED(
 766       TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.frames"),
 767       &frame_tracing_enabled);
 768   if (frame_tracing_enabled) {
 769     state->BeginDictionary("frame_source_");
 770     frame_source_->AsValueInto(state);
 771     state->EndDictionary();
 772   }
 773
 774   state->BeginDictionary("scheduler_state");
 775   state->SetDouble("time_until_anticipated_draw_time_ms",
 776                    (AnticipatedDrawTime() - Now()).InMillisecondsF());
 777   state->SetDouble("estimated_parent_draw_time_ms",
 778                    estimated_parent_draw_time_.InMillisecondsF());
 779   state->SetBoolean("last_set_needs_begin_frame_",
 780                     frame_source_->NeedsBeginFrames());
 781   state->SetInteger("begin_retro_frame_args_", begin_retro_frame_args_.size());
 782   state->SetBoolean("begin_retro_frame_task_",
 783                     !begin_retro_frame_task_.IsCancelled());
 784   state->SetBoolean("begin_impl_frame_deadline_task_",
 785                     !begin_impl_frame_deadline_task_.IsCancelled());
 786   state->SetBoolean("poll_for_draw_triggers_task_",
 787                     !poll_for_draw_triggers_task_.IsCancelled());
 788   state->SetBoolean("advance_commit_state_task_",
 789                     !advance_commit_state_task_.IsCancelled());
 790   state->BeginDictionary("begin_impl_frame_args");
 791   begin_impl_frame_args_.AsValueInto(state);
 792   state->EndDictionary();
 793
 794   base::TimeTicks now = Now();
 795   base::TimeTicks frame_time = begin_impl_frame_args_.frame_time;
 796   base::TimeTicks deadline = begin_impl_frame_args_.deadline;
 797   base::TimeDelta interval = begin_impl_frame_args_.interval;
 798   state->BeginDictionary("major_timestamps_in_ms");
 799   state->SetDouble("0_interval", interval.InMillisecondsF());
 800   state->SetDouble("1_now_to_deadline", (deadline - now).InMillisecondsF());
 801   state->SetDouble("2_frame_time_to_now", (now - frame_time).InMillisecondsF());
 802   state->SetDouble("3_frame_time_to_deadline",
 803                    (deadline - frame_time).InMillisecondsF());
 804   state->SetDouble("4_now", (now - base::TimeTicks()).InMillisecondsF());
 805   state->SetDouble("5_frame_time",
 806                    (frame_time - base::TimeTicks()).InMillisecondsF());
 807   state->SetDouble("6_deadline",
 808                    (deadline - base::TimeTicks()).InMillisecondsF());
 809   state->EndDictionary();
 810
 811   state->EndDictionary();
 812
 813   state->BeginDictionary("client_state");
 814   state->SetDouble("draw_duration_estimate_ms",
 815                    client_->DrawDurationEstimate().InMillisecondsF());
 816   state->SetDouble(
 817       "begin_main_frame_to_commit_duration_estimate_ms",
 818       client_->BeginMainFrameToCommitDurationEstimate().InMillisecondsF());
 819   state->SetDouble(
 820       "commit_to_activate_duration_estimate_ms",
 821       client_->CommitToActivateDurationEstimate().InMillisecondsF());
 822   state->EndDictionary();
 823 }
 824
 825 bool Scheduler::CanCommitAndActivateBeforeDeadline() const {
 826   // Check if the main thread computation and commit can be finished before the
 827   // impl thread's deadline.
 828   base::TimeTicks estimated_draw_time =
 829       begin_impl_frame_args_.frame_time +
 830       client_->BeginMainFrameToCommitDurationEstimate() +
 831       client_->CommitToActivateDurationEstimate();
 832
 833   TRACE_EVENT2(
 834       TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 835       "CanCommitAndActivateBeforeDeadline",
 836       "time_left_after_drawing_ms",
 837       (begin_impl_frame_args_.deadline - estimated_draw_time).InMillisecondsF(),
 838       "state",
 839       AsValue());
 840
 841   return estimated_draw_time < begin_impl_frame_args_.deadline;
 842 }
 843
 844 bool Scheduler::IsBeginMainFrameSentOrStarted() const {
 845   return (state_machine_.commit_state() ==
 846               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_SENT ||
 847           state_machine_.commit_state() ==
 848               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED);
 849 }
 850
 851 }  // namespace cc