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       begin_impl_frame_deadline_mode_(
  98           SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_NONE),
  99       state_machine_(scheduler_settings),
 100       inside_process_scheduled_actions_(false),
 101       inside_action_(SchedulerStateMachine::ACTION_NONE),
 102       weak_factory_(this) {
 103   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 104                "Scheduler::Scheduler",
 105                "settings",
 106                settings_.AsValue());
 107   DCHECK(client_);
 108   DCHECK(!state_machine_.BeginFrameNeeded());
 109
 110   begin_retro_frame_closure_ =
 111       base::Bind(&Scheduler::BeginRetroFrame, weak_factory_.GetWeakPtr());
 112   begin_impl_frame_deadline_closure_ = base::Bind(
 113       &Scheduler::OnBeginImplFrameDeadline, 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   // At this point we'd prefer to advance through the commit flow by
 335   // drawing a frame, however it's possible that the frame rate controller
 336   // will not give us a BeginFrame until the commit completes.  See
 337   // crbug.com/317430 for an example of a swap ack being held on commit. Thus
 338   // we set a repeating timer to poll on ProcessScheduledActions until we
 339   // successfully reach BeginFrame. Synchronous compositor does not use
 340   // frame rate controller or have the circular wait in the bug.
 341   if (IsBeginMainFrameSentOrStarted() &&
 342       !settings_.using_synchronous_renderer_compositor) {
 343     if (advance_commit_state_task_.IsCancelled() &&
 344         begin_impl_frame_args_.IsValid()) {
 345       // Since we'd rather get a BeginImplFrame by the normal mechanism, we
 346       // set the interval to twice the interval from the previous frame.
 347       advance_commit_state_task_.Reset(advance_commit_state_closure_);
 348       task_runner_->PostDelayedTask(FROM_HERE,
 349                                     advance_commit_state_task_.callback(),
 350                                     begin_impl_frame_args_.interval * 2);
 351     }
 352   } else {
 353     advance_commit_state_task_.Cancel();
 354   }
 355 }
 356
 357 // BeginFrame is the mechanism that tells us that now is a good time to start
 358 // making a frame. Usually this means that user input for the frame is complete.
 359 // If the scheduler is busy, we queue the BeginFrame to be handled later as
 360 // a BeginRetroFrame.
 361 bool Scheduler::OnBeginFrameMixInDelegate(const BeginFrameArgs& args) {
 362   TRACE_EVENT1("cc,benchmark", "Scheduler::BeginFrame", "args", args.AsValue());
 363
 364   // Deliver BeginFrames to children.
 365   if (state_machine_.children_need_begin_frames()) {
 366     BeginFrameArgs adjusted_args_for_children(args);
 367     // Adjust a deadline for child schedulers.
 368     // TODO(simonhong): Once we have commitless update, we can get rid of
 369     // BeginMainFrameToCommitDurationEstimate() +
 370     // CommitToActivateDurationEstimate().
 371     adjusted_args_for_children.deadline -=
 372         (client_->BeginMainFrameToCommitDurationEstimate() +
 373          client_->CommitToActivateDurationEstimate() +
 374          client_->DrawDurationEstimate() + EstimatedParentDrawTime());
 375     client_->SendBeginFramesToChildren(adjusted_args_for_children);
 376   }
 377
 378   BeginFrameArgs adjusted_args(args);
 379   adjusted_args.deadline -= EstimatedParentDrawTime();
 380
 381   if (settings_.using_synchronous_renderer_compositor) {
 382     BeginImplFrameSynchronous(adjusted_args);
 383     return true;
 384   }
 385
 386   // We have just called SetNeedsBeginFrame(true) and the BeginFrameSource has
 387   // sent us the last BeginFrame we have missed. As we might not be able to
 388   // actually make rendering for this call, handle it like a "retro frame".
 389   // TODO(brainderson): Add a test for this functionality ASAP!
 390   if (adjusted_args.type == BeginFrameArgs::MISSED) {
 391     begin_retro_frame_args_.push_back(adjusted_args);
 392     PostBeginRetroFrameIfNeeded();
 393     return true;
 394   }
 395
 396   bool should_defer_begin_frame =
 397       !begin_retro_frame_args_.empty() ||
 398       !begin_retro_frame_task_.IsCancelled() ||
 399       !frame_source_->NeedsBeginFrames() ||
 400       (state_machine_.begin_impl_frame_state() !=
 401        SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 402
 403   if (should_defer_begin_frame) {
 404     begin_retro_frame_args_.push_back(adjusted_args);
 405     TRACE_EVENT_INSTANT0(
 406         "cc", "Scheduler::BeginFrame deferred", TRACE_EVENT_SCOPE_THREAD);
 407     // Queuing the frame counts as "using it", so we need to return true.
 408   } else {
 409     BeginImplFrameWithDeadline(adjusted_args);
 410   }
 411   return true;
 412 }
 413
 414 void Scheduler::SetChildrenNeedBeginFrames(bool children_need_begin_frames) {
 415   state_machine_.SetChildrenNeedBeginFrames(children_need_begin_frames);
 416   ProcessScheduledActions();
 417 }
 418
 419 void Scheduler::SetAuthoritativeVSyncInterval(const base::TimeDelta& interval) {
 420   authoritative_vsync_interval_ = interval;
 421   if (vsync_observer_)
 422     vsync_observer_->OnUpdateVSyncParameters(last_vsync_timebase_, interval);
 423 }
 424
 425 void Scheduler::OnDrawForOutputSurface() {
 426   DCHECK(settings_.using_synchronous_renderer_compositor);
 427   DCHECK_EQ(state_machine_.begin_impl_frame_state(),
 428             SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 429   DCHECK(!BeginImplFrameDeadlinePending());
 430
 431   state_machine_.OnBeginImplFrameDeadline();
 432   ProcessScheduledActions();
 433
 434   state_machine_.OnBeginImplFrameIdle();
 435   ProcessScheduledActions();
 436 }
 437
 438 // BeginRetroFrame is called for BeginFrames that we've deferred because
 439 // the scheduler was in the middle of processing a previous BeginFrame.
 440 void Scheduler::BeginRetroFrame() {
 441   TRACE_EVENT0("cc,benchmark", "Scheduler::BeginRetroFrame");
 442   DCHECK(!settings_.using_synchronous_renderer_compositor);
 443   DCHECK(!begin_retro_frame_args_.empty());
 444   DCHECK(!begin_retro_frame_task_.IsCancelled());
 445   DCHECK_EQ(state_machine_.begin_impl_frame_state(),
 446             SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 447
 448   begin_retro_frame_task_.Cancel();
 449
 450   // Discard expired BeginRetroFrames
 451   // Today, we should always end up with at most one un-expired BeginRetroFrame
 452   // because deadlines will not be greater than the next frame time. We don't
 453   // DCHECK though because some systems don't always have monotonic timestamps.
 454   // TODO(brianderson): In the future, long deadlines could result in us not
 455   // draining the queue if we don't catch up. If we consistently can't catch
 456   // up, our fallback should be to lower our frame rate.
 457   base::TimeTicks now = Now();
 458
 459   while (!begin_retro_frame_args_.empty()) {
 460     const BeginFrameArgs& args = begin_retro_frame_args_.front();
 461     base::TimeTicks expiration_time = args.frame_time + args.interval;
 462     if (now <= expiration_time)
 463       break;
 464     TRACE_EVENT_INSTANT2(
 465         "cc", "Scheduler::BeginRetroFrame discarding", TRACE_EVENT_SCOPE_THREAD,
 466         "expiration_time - now", (expiration_time - now).InMillisecondsF(),
 467         "BeginFrameArgs", begin_retro_frame_args_.front().AsValue());
 468     begin_retro_frame_args_.pop_front();
 469     frame_source_->DidFinishFrame(begin_retro_frame_args_.size());
 470   }
 471
 472   if (begin_retro_frame_args_.empty()) {
 473     TRACE_EVENT_INSTANT0("cc",
 474                          "Scheduler::BeginRetroFrames all expired",
 475                          TRACE_EVENT_SCOPE_THREAD);
 476   } else {
 477     BeginFrameArgs front = begin_retro_frame_args_.front();
 478     begin_retro_frame_args_.pop_front();
 479     BeginImplFrameWithDeadline(front);
 480   }
 481 }
 482
 483 // There could be a race between the posted BeginRetroFrame and a new
 484 // BeginFrame arriving via the normal mechanism. Scheduler::BeginFrame
 485 // will check if there is a pending BeginRetroFrame to ensure we handle
 486 // BeginFrames in FIFO order.
 487 void Scheduler::PostBeginRetroFrameIfNeeded() {
 488   TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 489                "Scheduler::PostBeginRetroFrameIfNeeded",
 490                "state",
 491                AsValue());
 492   if (!frame_source_->NeedsBeginFrames())
 493     return;
 494
 495   if (begin_retro_frame_args_.empty() || !begin_retro_frame_task_.IsCancelled())
 496     return;
 497
 498   // begin_retro_frame_args_ should always be empty for the
 499   // synchronous compositor.
 500   DCHECK(!settings_.using_synchronous_renderer_compositor);
 501
 502   if (state_machine_.begin_impl_frame_state() !=
 503       SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE)
 504     return;
 505
 506   begin_retro_frame_task_.Reset(begin_retro_frame_closure_);
 507
 508   task_runner_->PostTask(FROM_HERE, begin_retro_frame_task_.callback());
 509 }
 510
 511 void Scheduler::BeginImplFrameWithDeadline(const BeginFrameArgs& args) {
 512   BeginImplFrame(args);
 513
 514   // The deadline will be scheduled in ProcessScheduledActions.
 515   state_machine_.OnBeginImplFrameDeadlinePending();
 516   ProcessScheduledActions();
 517 }
 518
 519 void Scheduler::BeginImplFrameSynchronous(const BeginFrameArgs& args) {
 520   BeginImplFrame(args);
 521   FinishImplFrame();
 522 }
 523
 524 void Scheduler::FinishImplFrame() {
 525   state_machine_.OnBeginImplFrameIdle();
 526   ProcessScheduledActions();
 527
 528   client_->DidBeginImplFrameDeadline();
 529   frame_source_->DidFinishFrame(begin_retro_frame_args_.size());
 530 }
 531
 532 // BeginImplFrame starts a compositor frame that will wait up until a deadline
 533 // for a BeginMainFrame+activation to complete before it times out and draws
 534 // any asynchronous animation and scroll/pinch updates.
 535 void Scheduler::BeginImplFrame(const BeginFrameArgs& args) {
 536   bool main_thread_is_in_high_latency_mode =
 537       state_machine_.MainThreadIsInHighLatencyMode();
 538   TRACE_EVENT2("cc,benchmark",
 539                "Scheduler::BeginImplFrame",
 540                "args",
 541                args.AsValue(),
 542                "main_thread_is_high_latency",
 543                main_thread_is_in_high_latency_mode);
 544   TRACE_COUNTER1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 545                  "MainThreadLatency",
 546                  main_thread_is_in_high_latency_mode);
 547   DCHECK_EQ(state_machine_.begin_impl_frame_state(),
 548             SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 549   DCHECK(!BeginImplFrameDeadlinePending());
 550   DCHECK(state_machine_.HasInitializedOutputSurface());
 551
 552   advance_commit_state_task_.Cancel();
 553
 554   begin_impl_frame_args_ = args;
 555   begin_impl_frame_args_.deadline -= client_->DrawDurationEstimate();
 556
 557   if (!state_machine_.impl_latency_takes_priority() &&
 558       main_thread_is_in_high_latency_mode &&
 559       CanCommitAndActivateBeforeDeadline()) {
 560     state_machine_.SetSkipNextBeginMainFrameToReduceLatency();
 561   }
 562
 563   state_machine_.OnBeginImplFrame();
 564   devtools_instrumentation::DidBeginFrame(layer_tree_host_id_);
 565   client_->WillBeginImplFrame(begin_impl_frame_args_);
 566
 567   ProcessScheduledActions();
 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_NONE:
 583       // No deadline.
 584       return;
 585     case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE:
 586       // We are ready to draw a new active tree immediately.
 587       // We don't use Now() here because it's somewhat expensive to call.
 588       deadline = base::TimeTicks();
 589       break;
 590     case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR:
 591       // We are animating on the impl thread but we can wait for some time.
 592       deadline = begin_impl_frame_args_.deadline;
 593       break;
 594     case SchedulerStateMachine::BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE:
 595       // We are blocked for one reason or another and we should wait.
 596       // TODO(brianderson): Handle long deadlines (that are past the next
 597       // frame's frame time) properly instead of using this hack.
 598       deadline =
 599           begin_impl_frame_args_.frame_time + begin_impl_frame_args_.interval;
 600       break;
 601   }
 602
 603   TRACE_EVENT2("cc", "Scheduler::ScheduleBeginImplFrameDeadline", "mode",
 604                SchedulerStateMachine::BeginImplFrameDeadlineModeToString(
 605                    begin_impl_frame_deadline_mode_),
 606                "deadline", deadline);
 607
 608   base::TimeDelta delta = std::max(deadline - Now(), base::TimeDelta());
 609   task_runner_->PostDelayedTask(
 610       FROM_HERE, begin_impl_frame_deadline_task_.callback(), delta);
 611 }
 612
 613 void Scheduler::ScheduleBeginImplFrameDeadlineIfNeeded() {
 614   if (settings_.using_synchronous_renderer_compositor)
 615     return;
 616
 617   if (state_machine_.begin_impl_frame_state() !=
 618       SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME)
 619     return;
 620
 621   if (begin_impl_frame_deadline_mode_ ==
 622           state_machine_.CurrentBeginImplFrameDeadlineMode() &&
 623       BeginImplFrameDeadlinePending())
 624     return;
 625
 626   ScheduleBeginImplFrameDeadline();
 627 }
 628
 629 void Scheduler::OnBeginImplFrameDeadline() {
 630   TRACE_EVENT0("cc,benchmark", "Scheduler::OnBeginImplFrameDeadline");
 631   begin_impl_frame_deadline_task_.Cancel();
 632   // We split the deadline actions up into two phases so the state machine
 633   // has a chance to trigger actions that should occur durring and after
 634   // the deadline separately. For example:
 635   // * Sending the BeginMainFrame will not occur after the deadline in
 636   //     order to wait for more user-input before starting the next commit.
 637   // * Creating a new OuputSurface will not occur during the deadline in
 638   //     order to allow the state machine to "settle" first.
 639
 640   // TODO(robliao): Remove ScopedTracker below once crbug.com/461509 is fixed.
 641   tracked_objects::ScopedTracker tracking_profile1(
 642       FROM_HERE_WITH_EXPLICIT_FUNCTION(
 643           "461509 Scheduler::OnBeginImplFrameDeadline1"));
 644   state_machine_.OnBeginImplFrameDeadline();
 645   ProcessScheduledActions();
 646   FinishImplFrame();
 647 }
 648
 649
 650 void Scheduler::PollToAdvanceCommitState() {
 651   TRACE_EVENT0("cc", "Scheduler::PollToAdvanceCommitState");
 652   advance_commit_state_task_.Cancel();
 653   ProcessScheduledActions();
 654 }
 655
 656 void Scheduler::DrawAndSwapIfPossible() {
 657   DrawResult result = client_->ScheduledActionDrawAndSwapIfPossible();
 658   state_machine_.DidDrawIfPossibleCompleted(result);
 659 }
 660
 661 void Scheduler::SetDeferCommits(bool defer_commits) {
 662   TRACE_EVENT1("cc", "Scheduler::SetDeferCommits",
 663                 "defer_commits",
 664                 defer_commits);
 665   state_machine_.SetDeferCommits(defer_commits);
 666   ProcessScheduledActions();
 667 }
 668
 669 void Scheduler::ProcessScheduledActions() {
 670   // We do not allow ProcessScheduledActions to be recursive.
 671   // The top-level call will iteratively execute the next action for us anyway.
 672   if (inside_process_scheduled_actions_)
 673     return;
 674
 675   base::AutoReset<bool> mark_inside(&inside_process_scheduled_actions_, true);
 676
 677   SchedulerStateMachine::Action action;
 678   do {
 679     action = state_machine_.NextAction();
 680     TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 681                  "SchedulerStateMachine",
 682                  "state",
 683                  AsValue());
 684     VLOG(2) << "Scheduler::ProcessScheduledActions: "
 685             << SchedulerStateMachine::ActionToString(action) << " "
 686             << state_machine_.GetStatesForDebugging();
 687     state_machine_.UpdateState(action);
 688     base::AutoReset<SchedulerStateMachine::Action>
 689         mark_inside_action(&inside_action_, action);
 690     switch (action) {
 691       case SchedulerStateMachine::ACTION_NONE:
 692         break;
 693       case SchedulerStateMachine::ACTION_ANIMATE:
 694         client_->ScheduledActionAnimate();
 695         break;
 696       case SchedulerStateMachine::ACTION_SEND_BEGIN_MAIN_FRAME:
 697         client_->ScheduledActionSendBeginMainFrame();
 698         break;
 699       case SchedulerStateMachine::ACTION_COMMIT: {
 700         // TODO(robliao): Remove ScopedTracker below once crbug.com/461509 is
 701         // fixed.
 702         tracked_objects::ScopedTracker tracking_profile4(
 703             FROM_HERE_WITH_EXPLICIT_FUNCTION(
 704                 "461509 Scheduler::ProcessScheduledActions4"));
 705         client_->ScheduledActionCommit();
 706         break;
 707       }
 708       case SchedulerStateMachine::ACTION_ACTIVATE_SYNC_TREE:
 709         client_->ScheduledActionActivateSyncTree();
 710         break;
 711       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_IF_POSSIBLE: {
 712         // TODO(robliao): Remove ScopedTracker below once crbug.com/461509 is
 713         // fixed.
 714         tracked_objects::ScopedTracker tracking_profile6(
 715             FROM_HERE_WITH_EXPLICIT_FUNCTION(
 716                 "461509 Scheduler::ProcessScheduledActions6"));
 717         DrawAndSwapIfPossible();
 718         break;
 719       }
 720       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_FORCED:
 721         client_->ScheduledActionDrawAndSwapForced();
 722         break;
 723       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_ABORT:
 724         // No action is actually performed, but this allows the state machine to
 725         // advance out of its waiting to draw state without actually drawing.
 726         break;
 727       case SchedulerStateMachine::ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
 728         client_->ScheduledActionBeginOutputSurfaceCreation();
 729         break;
 730       case SchedulerStateMachine::ACTION_PREPARE_TILES:
 731         client_->ScheduledActionPrepareTiles();
 732         break;
 733       case SchedulerStateMachine::ACTION_INVALIDATE_OUTPUT_SURFACE: {
 734         client_->ScheduledActionInvalidateOutputSurface();
 735         break;
 736       }
 737     }
 738   } while (action != SchedulerStateMachine::ACTION_NONE);
 739
 740   SetupPollingMechanisms();
 741
 742   client_->DidAnticipatedDrawTimeChange(AnticipatedDrawTime());
 743
 744   ScheduleBeginImplFrameDeadlineIfNeeded();
 745
 746   SetupNextBeginFrameIfNeeded();
 747 }
 748
 749 scoped_refptr<base::trace_event::ConvertableToTraceFormat> Scheduler::AsValue()
 750     const {
 751   scoped_refptr<base::trace_event::TracedValue> state =
 752       new base::trace_event::TracedValue();
 753   AsValueInto(state.get());
 754   return state;
 755 }
 756
 757 void Scheduler::AsValueInto(base::trace_event::TracedValue* state) const {
 758   state->BeginDictionary("state_machine");
 759   state_machine_.AsValueInto(state);
 760   state->EndDictionary();
 761
 762   // Only trace frame sources when explicitly enabled - http://crbug.com/420607
 763   bool frame_tracing_enabled = false;
 764   TRACE_EVENT_CATEGORY_GROUP_ENABLED(
 765       TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler.frames"),
 766       &frame_tracing_enabled);
 767   if (frame_tracing_enabled) {
 768     state->BeginDictionary("frame_source_");
 769     frame_source_->AsValueInto(state);
 770     state->EndDictionary();
 771   }
 772
 773   state->BeginDictionary("scheduler_state");
 774   state->SetDouble("time_until_anticipated_draw_time_ms",
 775                    (AnticipatedDrawTime() - Now()).InMillisecondsF());
 776   state->SetDouble("estimated_parent_draw_time_ms",
 777                    estimated_parent_draw_time_.InMillisecondsF());
 778   state->SetBoolean("last_set_needs_begin_frame_",
 779                     frame_source_->NeedsBeginFrames());
 780   state->SetInteger("begin_retro_frame_args_", begin_retro_frame_args_.size());
 781   state->SetBoolean("begin_retro_frame_task_",
 782                     !begin_retro_frame_task_.IsCancelled());
 783   state->SetBoolean("begin_impl_frame_deadline_task_",
 784                     !begin_impl_frame_deadline_task_.IsCancelled());
 785   state->SetBoolean("advance_commit_state_task_",
 786                     !advance_commit_state_task_.IsCancelled());
 787   state->BeginDictionary("begin_impl_frame_args");
 788   begin_impl_frame_args_.AsValueInto(state);
 789   state->EndDictionary();
 790
 791   base::TimeTicks now = Now();
 792   base::TimeTicks frame_time = begin_impl_frame_args_.frame_time;
 793   base::TimeTicks deadline = begin_impl_frame_args_.deadline;
 794   base::TimeDelta interval = begin_impl_frame_args_.interval;
 795   state->BeginDictionary("major_timestamps_in_ms");
 796   state->SetDouble("0_interval", interval.InMillisecondsF());
 797   state->SetDouble("1_now_to_deadline", (deadline - now).InMillisecondsF());
 798   state->SetDouble("2_frame_time_to_now", (now - frame_time).InMillisecondsF());
 799   state->SetDouble("3_frame_time_to_deadline",
 800                    (deadline - frame_time).InMillisecondsF());
 801   state->SetDouble("4_now", (now - base::TimeTicks()).InMillisecondsF());
 802   state->SetDouble("5_frame_time",
 803                    (frame_time - base::TimeTicks()).InMillisecondsF());
 804   state->SetDouble("6_deadline",
 805                    (deadline - base::TimeTicks()).InMillisecondsF());
 806   state->EndDictionary();
 807
 808   state->EndDictionary();
 809
 810   state->BeginDictionary("client_state");
 811   state->SetDouble("draw_duration_estimate_ms",
 812                    client_->DrawDurationEstimate().InMillisecondsF());
 813   state->SetDouble(
 814       "begin_main_frame_to_commit_duration_estimate_ms",
 815       client_->BeginMainFrameToCommitDurationEstimate().InMillisecondsF());
 816   state->SetDouble(
 817       "commit_to_activate_duration_estimate_ms",
 818       client_->CommitToActivateDurationEstimate().InMillisecondsF());
 819   state->EndDictionary();
 820 }
 821
 822 bool Scheduler::CanCommitAndActivateBeforeDeadline() const {
 823   // Check if the main thread computation and commit can be finished before the
 824   // impl thread's deadline.
 825   base::TimeTicks estimated_draw_time =
 826       begin_impl_frame_args_.frame_time +
 827       client_->BeginMainFrameToCommitDurationEstimate() +
 828       client_->CommitToActivateDurationEstimate();
 829
 830   TRACE_EVENT2(
 831       TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 832       "CanCommitAndActivateBeforeDeadline",
 833       "time_left_after_drawing_ms",
 834       (begin_impl_frame_args_.deadline - estimated_draw_time).InMillisecondsF(),
 835       "state",
 836       AsValue());
 837
 838   return estimated_draw_time < begin_impl_frame_args_.deadline;
 839 }
 840
 841 bool Scheduler::IsBeginMainFrameSentOrStarted() const {
 842   return (state_machine_.commit_state() ==
 843               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_SENT ||
 844           state_machine_.commit_state() ==
 845               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED);
 846 }
 847
 848 }  // namespace cc