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