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