src/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 #include "base/auto_reset.h"
   9 #include "base/debug/trace_event.h"
  10 #include "base/logging.h"
  11 #include "cc/debug/devtools_instrumentation.h"
  12 #include "cc/debug/traced_value.h"
  13 #include "cc/scheduler/delay_based_time_source.h"
  14 #include "ui/gfx/frame_time.h"
  15
  16 namespace cc {
  17
  18 class SyntheticBeginFrameSource : public TimeSourceClient {
  19  public:
  20   SyntheticBeginFrameSource(Scheduler* scheduler,
  21                             base::SingleThreadTaskRunner* task_runner)
  22       : scheduler_(scheduler) {
  23     if (gfx::FrameTime::TimestampsAreHighRes()) {
  24       time_source_ = DelayBasedTimeSourceHighRes::Create(
  25           scheduler_->VSyncInterval(), task_runner);
  26     } else {
  27       time_source_ = DelayBasedTimeSource::Create(scheduler_->VSyncInterval(),
  28                                                   task_runner);
  29     }
  30     time_source_->SetClient(this);
  31   }
  32
  33   virtual ~SyntheticBeginFrameSource() {}
  34
  35   // Updates the phase and frequency of the timer.
  36   void CommitVSyncParameters(base::TimeTicks timebase,
  37                              base::TimeDelta interval) {
  38     time_source_->SetTimebaseAndInterval(timebase, interval);
  39   }
  40
  41   // Activates future BeginFrames and, if activating, pushes the most
  42   // recently missed BeginFrame to the back of a retroactive queue.
  43   void SetNeedsBeginFrame(bool needs_begin_frame,
  44                           std::deque<BeginFrameArgs>* begin_retro_frame_args) {
  45     base::TimeTicks missed_tick_time =
  46         time_source_->SetActive(needs_begin_frame);
  47     if (!missed_tick_time.is_null()) {
  48       begin_retro_frame_args->push_back(
  49           CreateSyntheticBeginFrameArgs(missed_tick_time));
  50     }
  51   }
  52
  53   // TimeSourceClient implementation of OnTimerTick triggers a BeginFrame.
  54   virtual void OnTimerTick() OVERRIDE {
  55     BeginFrameArgs begin_frame_args(
  56         CreateSyntheticBeginFrameArgs(time_source_->LastTickTime()));
  57     scheduler_->BeginFrame(begin_frame_args);
  58   }
  59
  60  private:
  61   BeginFrameArgs CreateSyntheticBeginFrameArgs(base::TimeTicks frame_time) {
  62     base::TimeTicks deadline =
  63         time_source_->NextTickTime() - scheduler_->EstimatedParentDrawTime();
  64     return BeginFrameArgs::Create(
  65         frame_time, deadline, scheduler_->VSyncInterval());
  66   }
  67
  68   Scheduler* scheduler_;
  69   scoped_refptr<TimeSource> time_source_;
  70 };
  71
  72 Scheduler::Scheduler(
  73     SchedulerClient* client,
  74     const SchedulerSettings& scheduler_settings,
  75     int layer_tree_host_id,
  76     const scoped_refptr<base::SingleThreadTaskRunner>& impl_task_runner)
  77     : settings_(scheduler_settings),
  78       client_(client),
  79       layer_tree_host_id_(layer_tree_host_id),
  80       impl_task_runner_(impl_task_runner),
  81       vsync_interval_(BeginFrameArgs::DefaultInterval()),
  82       last_set_needs_begin_frame_(false),
  83       begin_unthrottled_frame_posted_(false),
  84       begin_retro_frame_posted_(false),
  85       state_machine_(scheduler_settings),
  86       inside_process_scheduled_actions_(false),
  87       inside_action_(SchedulerStateMachine::ACTION_NONE),
  88       weak_factory_(this) {
  89   DCHECK(client_);
  90   DCHECK(!state_machine_.BeginFrameNeeded());
  91   if (settings_.main_frame_before_activation_enabled) {
  92     DCHECK(settings_.main_frame_before_draw_enabled);
  93   }
  94
  95   begin_retro_frame_closure_ =
  96       base::Bind(&Scheduler::BeginRetroFrame, weak_factory_.GetWeakPtr());
  97   begin_unthrottled_frame_closure_ =
  98       base::Bind(&Scheduler::BeginUnthrottledFrame, weak_factory_.GetWeakPtr());
  99   begin_impl_frame_deadline_closure_ = base::Bind(
 100       &Scheduler::OnBeginImplFrameDeadline, weak_factory_.GetWeakPtr());
 101   poll_for_draw_triggers_closure_ = base::Bind(
 102       &Scheduler::PollForAnticipatedDrawTriggers, weak_factory_.GetWeakPtr());
 103   advance_commit_state_closure_ = base::Bind(
 104       &Scheduler::PollToAdvanceCommitState, weak_factory_.GetWeakPtr());
 105
 106   if (!settings_.begin_frame_scheduling_enabled) {
 107     SetupSyntheticBeginFrames();
 108   }
 109 }
 110
 111 Scheduler::~Scheduler() {
 112   if (synthetic_begin_frame_source_) {
 113     synthetic_begin_frame_source_->SetNeedsBeginFrame(false,
 114                                                       &begin_retro_frame_args_);
 115   }
 116 }
 117
 118 void Scheduler::SetupSyntheticBeginFrames() {
 119   DCHECK(!synthetic_begin_frame_source_);
 120   synthetic_begin_frame_source_.reset(
 121       new SyntheticBeginFrameSource(this, impl_task_runner_.get()));
 122 }
 123
 124 void Scheduler::CommitVSyncParameters(base::TimeTicks timebase,
 125                                       base::TimeDelta interval) {
 126   // TODO(brianderson): We should not be receiving 0 intervals.
 127   if (interval == base::TimeDelta())
 128     interval = BeginFrameArgs::DefaultInterval();
 129   vsync_interval_ = interval;
 130   if (!settings_.begin_frame_scheduling_enabled)
 131     synthetic_begin_frame_source_->CommitVSyncParameters(timebase, interval);
 132 }
 133
 134 void Scheduler::SetEstimatedParentDrawTime(base::TimeDelta draw_time) {
 135   estimated_parent_draw_time_ = draw_time;
 136 }
 137
 138 void Scheduler::SetCanStart() {
 139   state_machine_.SetCanStart();
 140   ProcessScheduledActions();
 141 }
 142
 143 void Scheduler::SetVisible(bool visible) {
 144   state_machine_.SetVisible(visible);
 145   ProcessScheduledActions();
 146 }
 147
 148 void Scheduler::SetCanDraw(bool can_draw) {
 149   state_machine_.SetCanDraw(can_draw);
 150   ProcessScheduledActions();
 151 }
 152
 153 void Scheduler::NotifyReadyToActivate() {
 154   state_machine_.NotifyReadyToActivate();
 155   ProcessScheduledActions();
 156 }
 157
 158 void Scheduler::ActivatePendingTree() {
 159   client_->ScheduledActionActivatePendingTree();
 160 }
 161
 162 void Scheduler::SetNeedsCommit() {
 163   state_machine_.SetNeedsCommit();
 164   ProcessScheduledActions();
 165 }
 166
 167 void Scheduler::SetNeedsForcedCommitForReadback() {
 168   state_machine_.SetNeedsForcedCommitForReadback();
 169   ProcessScheduledActions();
 170 }
 171
 172 void Scheduler::SetNeedsRedraw() {
 173   state_machine_.SetNeedsRedraw();
 174   ProcessScheduledActions();
 175 }
 176
 177 void Scheduler::SetNeedsAnimate() {
 178   state_machine_.SetNeedsAnimate();
 179   ProcessScheduledActions();
 180 }
 181
 182 void Scheduler::SetNeedsManageTiles() {
 183   DCHECK(!IsInsideAction(SchedulerStateMachine::ACTION_MANAGE_TILES));
 184   state_machine_.SetNeedsManageTiles();
 185   ProcessScheduledActions();
 186 }
 187
 188 void Scheduler::SetMaxSwapsPending(int max) {
 189   state_machine_.SetMaxSwapsPending(max);
 190 }
 191
 192 void Scheduler::DidSwapBuffers() {
 193   state_machine_.DidSwapBuffers();
 194   // There is no need to call ProcessScheduledActions here because
 195   // swapping should not trigger any new actions.
 196   if (!inside_process_scheduled_actions_) {
 197     DCHECK_EQ(state_machine_.NextAction(), SchedulerStateMachine::ACTION_NONE);
 198   }
 199 }
 200
 201 void Scheduler::SetSwapUsedIncompleteTile(bool used_incomplete_tile) {
 202   state_machine_.SetSwapUsedIncompleteTile(used_incomplete_tile);
 203   ProcessScheduledActions();
 204 }
 205
 206 void Scheduler::DidSwapBuffersComplete() {
 207   state_machine_.DidSwapBuffersComplete();
 208   ProcessScheduledActions();
 209 }
 210
 211 void Scheduler::SetSmoothnessTakesPriority(bool smoothness_takes_priority) {
 212   state_machine_.SetSmoothnessTakesPriority(smoothness_takes_priority);
 213   ProcessScheduledActions();
 214 }
 215
 216 void Scheduler::NotifyReadyToCommit() {
 217   TRACE_EVENT0("cc", "Scheduler::NotifyReadyToCommit");
 218   state_machine_.NotifyReadyToCommit();
 219   ProcessScheduledActions();
 220 }
 221
 222 void Scheduler::BeginMainFrameAborted(bool did_handle) {
 223   TRACE_EVENT0("cc", "Scheduler::BeginMainFrameAborted");
 224   state_machine_.BeginMainFrameAborted(did_handle);
 225   ProcessScheduledActions();
 226 }
 227
 228 void Scheduler::DidManageTiles() {
 229   state_machine_.DidManageTiles();
 230 }
 231
 232 void Scheduler::DidLoseOutputSurface() {
 233   TRACE_EVENT0("cc", "Scheduler::DidLoseOutputSurface");
 234   state_machine_.DidLoseOutputSurface();
 235   last_set_needs_begin_frame_ = false;
 236   begin_retro_frame_args_.clear();
 237   ProcessScheduledActions();
 238 }
 239
 240 void Scheduler::DidCreateAndInitializeOutputSurface() {
 241   TRACE_EVENT0("cc", "Scheduler::DidCreateAndInitializeOutputSurface");
 242   DCHECK(!last_set_needs_begin_frame_);
 243   DCHECK(begin_impl_frame_deadline_task_.IsCancelled());
 244   state_machine_.DidCreateAndInitializeOutputSurface();
 245   ProcessScheduledActions();
 246 }
 247
 248 void Scheduler::NotifyBeginMainFrameStarted() {
 249   TRACE_EVENT0("cc", "Scheduler::NotifyBeginMainFrameStarted");
 250   state_machine_.NotifyBeginMainFrameStarted();
 251 }
 252
 253 base::TimeTicks Scheduler::AnticipatedDrawTime() const {
 254   if (!last_set_needs_begin_frame_ ||
 255       begin_impl_frame_args_.interval <= base::TimeDelta())
 256     return base::TimeTicks();
 257
 258   base::TimeTicks now = gfx::FrameTime::Now();
 259   base::TimeTicks timebase = std::max(begin_impl_frame_args_.frame_time,
 260                                       begin_impl_frame_args_.deadline);
 261   int64 intervals = 1 + ((now - timebase) / begin_impl_frame_args_.interval);
 262   return timebase + (begin_impl_frame_args_.interval * intervals);
 263 }
 264
 265 base::TimeTicks Scheduler::LastBeginImplFrameTime() {
 266   return begin_impl_frame_args_.frame_time;
 267 }
 268
 269 void Scheduler::SetupNextBeginFrameIfNeeded() {
 270   bool needs_begin_frame = state_machine_.BeginFrameNeeded();
 271
 272   if (settings_.throttle_frame_production) {
 273     SetupNextBeginFrameWhenVSyncThrottlingEnabled(needs_begin_frame);
 274   } else {
 275     SetupNextBeginFrameWhenVSyncThrottlingDisabled(needs_begin_frame);
 276   }
 277   SetupPollingMechanisms(needs_begin_frame);
 278 }
 279
 280 // When we are throttling frame production, we request BeginFrames
 281 // from the OutputSurface.
 282 void Scheduler::SetupNextBeginFrameWhenVSyncThrottlingEnabled(
 283     bool needs_begin_frame) {
 284   bool at_end_of_deadline =
 285       state_machine_.begin_impl_frame_state() ==
 286           SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE;
 287
 288   bool should_call_set_needs_begin_frame =
 289       // Always request the BeginFrame immediately if it wasn't needed before.
 290       (needs_begin_frame && !last_set_needs_begin_frame_) ||
 291       // Only stop requesting BeginFrames after a deadline.
 292       (!needs_begin_frame && last_set_needs_begin_frame_ && at_end_of_deadline);
 293
 294   if (should_call_set_needs_begin_frame) {
 295     if (settings_.begin_frame_scheduling_enabled) {
 296       client_->SetNeedsBeginFrame(needs_begin_frame);
 297     } else {
 298       synthetic_begin_frame_source_->SetNeedsBeginFrame(
 299           needs_begin_frame, &begin_retro_frame_args_);
 300     }
 301     last_set_needs_begin_frame_ = needs_begin_frame;
 302   }
 303
 304   PostBeginRetroFrameIfNeeded();
 305 }
 306
 307 // When we aren't throttling frame production, we initiate a BeginFrame
 308 // as soon as one is needed.
 309 void Scheduler::SetupNextBeginFrameWhenVSyncThrottlingDisabled(
 310     bool needs_begin_frame) {
 311   last_set_needs_begin_frame_ = needs_begin_frame;
 312
 313   if (!needs_begin_frame || begin_unthrottled_frame_posted_)
 314     return;
 315
 316   if (state_machine_.begin_impl_frame_state() !=
 317           SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE &&
 318       state_machine_.begin_impl_frame_state() !=
 319           SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE) {
 320     return;
 321   }
 322
 323   begin_unthrottled_frame_posted_ = true;
 324   impl_task_runner_->PostTask(FROM_HERE, begin_unthrottled_frame_closure_);
 325 }
 326
 327 // BeginUnthrottledFrame is used when we aren't throttling frame production.
 328 // This will usually be because VSync is disabled.
 329 void Scheduler::BeginUnthrottledFrame() {
 330   DCHECK(!settings_.throttle_frame_production);
 331   DCHECK(begin_retro_frame_args_.empty());
 332
 333   base::TimeTicks now = gfx::FrameTime::Now();
 334   base::TimeTicks deadline = now + vsync_interval_;
 335
 336   BeginFrameArgs begin_frame_args =
 337       BeginFrameArgs::Create(now, deadline, vsync_interval_);
 338   BeginImplFrame(begin_frame_args);
 339
 340   begin_unthrottled_frame_posted_ = false;
 341 }
 342
 343 // We may need to poll when we can't rely on BeginFrame to advance certain
 344 // state or to avoid deadlock.
 345 void Scheduler::SetupPollingMechanisms(bool needs_begin_frame) {
 346   bool needs_advance_commit_state_timer = false;
 347   // Setup PollForAnticipatedDrawTriggers if we need to monitor state but
 348   // aren't expecting any more BeginFrames. This should only be needed by
 349   // the synchronous compositor when BeginFrameNeeded is false.
 350   if (state_machine_.ShouldPollForAnticipatedDrawTriggers()) {
 351     DCHECK(!state_machine_.SupportsProactiveBeginFrame());
 352     DCHECK(!needs_begin_frame);
 353     if (poll_for_draw_triggers_task_.IsCancelled()) {
 354       poll_for_draw_triggers_task_.Reset(poll_for_draw_triggers_closure_);
 355       base::TimeDelta delay = begin_impl_frame_args_.IsValid()
 356                                   ? begin_impl_frame_args_.interval
 357                                   : BeginFrameArgs::DefaultInterval();
 358       impl_task_runner_->PostDelayedTask(
 359           FROM_HERE, poll_for_draw_triggers_task_.callback(), delay);
 360     }
 361   } else {
 362     poll_for_draw_triggers_task_.Cancel();
 363
 364     // At this point we'd prefer to advance through the commit flow by
 365     // drawing a frame, however it's possible that the frame rate controller
 366     // will not give us a BeginFrame until the commit completes.  See
 367     // crbug.com/317430 for an example of a swap ack being held on commit. Thus
 368     // we set a repeating timer to poll on ProcessScheduledActions until we
 369     // successfully reach BeginFrame. Synchronous compositor does not use
 370     // frame rate controller or have the circular wait in the bug.
 371     if (IsBeginMainFrameSentOrStarted() &&
 372         !settings_.using_synchronous_renderer_compositor) {
 373       needs_advance_commit_state_timer = true;
 374     }
 375   }
 376
 377   if (needs_advance_commit_state_timer) {
 378     if (advance_commit_state_task_.IsCancelled() &&
 379         begin_impl_frame_args_.IsValid()) {
 380       // Since we'd rather get a BeginImplFrame by the normal mechanism, we
 381       // set the interval to twice the interval from the previous frame.
 382       advance_commit_state_task_.Reset(advance_commit_state_closure_);
 383       impl_task_runner_->PostDelayedTask(FROM_HERE,
 384                                          advance_commit_state_task_.callback(),
 385                                          begin_impl_frame_args_.interval * 2);
 386     }
 387   } else {
 388     advance_commit_state_task_.Cancel();
 389   }
 390 }
 391
 392 // BeginFrame is the mechanism that tells us that now is a good time to start
 393 // making a frame. Usually this means that user input for the frame is complete.
 394 // If the scheduler is busy, we queue the BeginFrame to be handled later as
 395 // a BeginRetroFrame.
 396 void Scheduler::BeginFrame(const BeginFrameArgs& args) {
 397   TRACE_EVENT1("cc", "Scheduler::BeginFrame", "frame_time", args.frame_time);
 398   DCHECK(settings_.throttle_frame_production);
 399
 400   bool should_defer_begin_frame;
 401   if (settings_.using_synchronous_renderer_compositor) {
 402     should_defer_begin_frame = false;
 403   } else {
 404     should_defer_begin_frame =
 405         !begin_retro_frame_args_.empty() || begin_retro_frame_posted_ ||
 406         !last_set_needs_begin_frame_ ||
 407         (state_machine_.begin_impl_frame_state() !=
 408          SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 409   }
 410
 411   if (should_defer_begin_frame) {
 412     begin_retro_frame_args_.push_back(args);
 413     TRACE_EVENT_INSTANT0(
 414         "cc", "Scheduler::BeginFrame deferred", TRACE_EVENT_SCOPE_THREAD);
 415     return;
 416   }
 417
 418   BeginImplFrame(args);
 419 }
 420
 421 // BeginRetroFrame is called for BeginFrames that we've deferred because
 422 // the scheduler was in the middle of processing a previous BeginFrame.
 423 void Scheduler::BeginRetroFrame() {
 424   TRACE_EVENT0("cc", "Scheduler::BeginRetroFrame");
 425   DCHECK(!settings_.using_synchronous_renderer_compositor);
 426   DCHECK(begin_retro_frame_posted_);
 427   begin_retro_frame_posted_ = false;
 428
 429   // If there aren't any retroactive BeginFrames, then we've lost the
 430   // OutputSurface and should abort.
 431   if (begin_retro_frame_args_.empty())
 432     return;
 433
 434   // Discard expired BeginRetroFrames
 435   // Today, we should always end up with at most one un-expired BeginRetroFrame
 436   // because deadlines will not be greater than the next frame time. We don't
 437   // DCHECK though because some systems don't always have monotonic timestamps.
 438   // TODO(brianderson): In the future, long deadlines could result in us not
 439   // draining the queue if we don't catch up. If we consistently can't catch
 440   // up, our fallback should be to lower our frame rate.
 441   base::TimeTicks now = gfx::FrameTime::Now();
 442   base::TimeDelta draw_duration_estimate = client_->DrawDurationEstimate();
 443   while (!begin_retro_frame_args_.empty() &&
 444          now > AdjustedBeginImplFrameDeadline(begin_retro_frame_args_.front(),
 445                                               draw_duration_estimate)) {
 446     TRACE_EVENT1("cc",
 447                  "Scheduler::BeginRetroFrame discarding",
 448                  "frame_time",
 449                  begin_retro_frame_args_.front().frame_time);
 450     begin_retro_frame_args_.pop_front();
 451   }
 452
 453   if (begin_retro_frame_args_.empty()) {
 454     DCHECK(settings_.throttle_frame_production);
 455     TRACE_EVENT_INSTANT0("cc",
 456                          "Scheduler::BeginRetroFrames all expired",
 457                          TRACE_EVENT_SCOPE_THREAD);
 458   } else {
 459     BeginImplFrame(begin_retro_frame_args_.front());
 460     begin_retro_frame_args_.pop_front();
 461   }
 462 }
 463
 464 // There could be a race between the posted BeginRetroFrame and a new
 465 // BeginFrame arriving via the normal mechanism. Scheduler::BeginFrame
 466 // will check if there is a pending BeginRetroFrame to ensure we handle
 467 // BeginFrames in FIFO order.
 468 void Scheduler::PostBeginRetroFrameIfNeeded() {
 469   if (!last_set_needs_begin_frame_)
 470     return;
 471
 472   if (begin_retro_frame_args_.empty() || begin_retro_frame_posted_)
 473     return;
 474
 475   // begin_retro_frame_args_ should always be empty for the
 476   // synchronous compositor.
 477   DCHECK(!settings_.using_synchronous_renderer_compositor);
 478
 479   if (state_machine_.begin_impl_frame_state() !=
 480       SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE)
 481     return;
 482
 483   begin_retro_frame_posted_ = true;
 484   impl_task_runner_->PostTask(FROM_HERE, begin_retro_frame_closure_);
 485 }
 486
 487 // BeginImplFrame starts a compositor frame that will wait up until a deadline
 488 // for a BeginMainFrame+activation to complete before it times out and draws
 489 // any asynchronous animation and scroll/pinch updates.
 490 void Scheduler::BeginImplFrame(const BeginFrameArgs& args) {
 491   TRACE_EVENT1(
 492       "cc", "Scheduler::BeginImplFrame", "frame_time", args.frame_time);
 493   DCHECK(state_machine_.begin_impl_frame_state() ==
 494          SchedulerStateMachine::BEGIN_IMPL_FRAME_STATE_IDLE);
 495   DCHECK(state_machine_.HasInitializedOutputSurface());
 496
 497   advance_commit_state_task_.Cancel();
 498
 499   base::TimeDelta draw_duration_estimate = client_->DrawDurationEstimate();
 500   begin_impl_frame_args_ = args;
 501   begin_impl_frame_args_.deadline -= draw_duration_estimate;
 502
 503   if (!state_machine_.smoothness_takes_priority() &&
 504       state_machine_.MainThreadIsInHighLatencyMode() &&
 505       CanCommitAndActivateBeforeDeadline()) {
 506     state_machine_.SetSkipNextBeginMainFrameToReduceLatency();
 507   }
 508
 509   client_->WillBeginImplFrame(begin_impl_frame_args_);
 510   state_machine_.OnBeginImplFrame(begin_impl_frame_args_);
 511   devtools_instrumentation::DidBeginFrame(layer_tree_host_id_);
 512
 513   ProcessScheduledActions();
 514
 515   state_machine_.OnBeginImplFrameDeadlinePending();
 516   ScheduleBeginImplFrameDeadline(
 517       AdjustedBeginImplFrameDeadline(args, draw_duration_estimate));
 518 }
 519
 520 base::TimeTicks Scheduler::AdjustedBeginImplFrameDeadline(
 521     const BeginFrameArgs& args,
 522     base::TimeDelta draw_duration_estimate) const {
 523   if (settings_.using_synchronous_renderer_compositor) {
 524     // The synchronous compositor needs to draw right away.
 525     return base::TimeTicks();
 526   } else if (state_machine_.ShouldTriggerBeginImplFrameDeadlineEarly()) {
 527     // We are ready to draw a new active tree immediately.
 528     return base::TimeTicks();
 529   } else if (state_machine_.needs_redraw()) {
 530     // We have an animation or fast input path on the impl thread that wants
 531     // to draw, so don't wait too long for a new active tree.
 532     return args.deadline - draw_duration_estimate;
 533   } else {
 534     // The impl thread doesn't have anything it wants to draw and we are just
 535     // waiting for a new active tree, so post the deadline for the next
 536     // expected BeginImplFrame start. This allows us to draw immediately when
 537     // there is a new active tree, instead of waiting for the next
 538     // BeginImplFrame.
 539     // TODO(brianderson): Handle long deadlines (that are past the next frame's
 540     // frame time) properly instead of using this hack.
 541     return args.frame_time + args.interval;
 542   }
 543 }
 544
 545 void Scheduler::ScheduleBeginImplFrameDeadline(base::TimeTicks deadline) {
 546   if (settings_.using_synchronous_renderer_compositor) {
 547     // The synchronous renderer compositor has to make its GL calls
 548     // within this call.
 549     // TODO(brianderson): Have the OutputSurface initiate the deadline tasks
 550     // so the sychronous renderer compositor can take advantage of splitting
 551     // up the BeginImplFrame and deadline as well.
 552     OnBeginImplFrameDeadline();
 553     return;
 554   }
 555   begin_impl_frame_deadline_task_.Cancel();
 556   begin_impl_frame_deadline_task_.Reset(begin_impl_frame_deadline_closure_);
 557
 558   base::TimeDelta delta = deadline - gfx::FrameTime::Now();
 559   if (delta <= base::TimeDelta())
 560     delta = base::TimeDelta();
 561   impl_task_runner_->PostDelayedTask(
 562       FROM_HERE, begin_impl_frame_deadline_task_.callback(), delta);
 563 }
 564
 565 void Scheduler::OnBeginImplFrameDeadline() {
 566   TRACE_EVENT0("cc", "Scheduler::OnBeginImplFrameDeadline");
 567   begin_impl_frame_deadline_task_.Cancel();
 568
 569   // We split the deadline actions up into two phases so the state machine
 570   // has a chance to trigger actions that should occur durring and after
 571   // the deadline separately. For example:
 572   // * Sending the BeginMainFrame will not occur after the deadline in
 573   //     order to wait for more user-input before starting the next commit.
 574   // * Creating a new OuputSurface will not occur during the deadline in
 575   //     order to allow the state machine to "settle" first.
 576   state_machine_.OnBeginImplFrameDeadline();
 577   ProcessScheduledActions();
 578   state_machine_.OnBeginImplFrameIdle();
 579   ProcessScheduledActions();
 580
 581   client_->DidBeginImplFrameDeadline();
 582 }
 583
 584 void Scheduler::PollForAnticipatedDrawTriggers() {
 585   TRACE_EVENT0("cc", "Scheduler::PollForAnticipatedDrawTriggers");
 586   poll_for_draw_triggers_task_.Cancel();
 587   state_machine_.DidEnterPollForAnticipatedDrawTriggers();
 588   ProcessScheduledActions();
 589   state_machine_.DidLeavePollForAnticipatedDrawTriggers();
 590 }
 591
 592 void Scheduler::PollToAdvanceCommitState() {
 593   TRACE_EVENT0("cc", "Scheduler::PollToAdvanceCommitState");
 594   advance_commit_state_task_.Cancel();
 595   ProcessScheduledActions();
 596 }
 597
 598 bool Scheduler::IsBeginMainFrameSent() const {
 599   return state_machine_.commit_state() ==
 600          SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_SENT;
 601 }
 602
 603 void Scheduler::DrawAndSwapIfPossible() {
 604   DrawSwapReadbackResult result =
 605       client_->ScheduledActionDrawAndSwapIfPossible();
 606   state_machine_.DidDrawIfPossibleCompleted(result.draw_result);
 607 }
 608
 609 void Scheduler::DrawAndSwapForced() {
 610   client_->ScheduledActionDrawAndSwapForced();
 611 }
 612
 613 void Scheduler::DrawAndReadback() {
 614   DrawSwapReadbackResult result = client_->ScheduledActionDrawAndReadback();
 615   DCHECK(!result.did_request_swap);
 616 }
 617
 618 void Scheduler::ProcessScheduledActions() {
 619   // We do not allow ProcessScheduledActions to be recursive.
 620   // The top-level call will iteratively execute the next action for us anyway.
 621   if (inside_process_scheduled_actions_)
 622     return;
 623
 624   base::AutoReset<bool> mark_inside(&inside_process_scheduled_actions_, true);
 625
 626   SchedulerStateMachine::Action action;
 627   do {
 628     state_machine_.CheckInvariants();
 629     action = state_machine_.NextAction();
 630     TRACE_EVENT1(TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 631                  "SchedulerStateMachine",
 632                  "state",
 633                  TracedValue::FromValue(StateAsValue().release()));
 634     state_machine_.UpdateState(action);
 635     base::AutoReset<SchedulerStateMachine::Action>
 636         mark_inside_action(&inside_action_, action);
 637     switch (action) {
 638       case SchedulerStateMachine::ACTION_NONE:
 639         break;
 640       case SchedulerStateMachine::ACTION_ANIMATE:
 641         client_->ScheduledActionAnimate();
 642         break;
 643       case SchedulerStateMachine::ACTION_SEND_BEGIN_MAIN_FRAME:
 644         client_->ScheduledActionSendBeginMainFrame();
 645         break;
 646       case SchedulerStateMachine::ACTION_COMMIT:
 647         client_->ScheduledActionCommit();
 648         break;
 649       case SchedulerStateMachine::ACTION_UPDATE_VISIBLE_TILES:
 650         client_->ScheduledActionUpdateVisibleTiles();
 651         break;
 652       case SchedulerStateMachine::ACTION_ACTIVATE_PENDING_TREE:
 653         ActivatePendingTree();
 654         break;
 655       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_IF_POSSIBLE:
 656         DrawAndSwapIfPossible();
 657         break;
 658       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_FORCED:
 659         DrawAndSwapForced();
 660         break;
 661       case SchedulerStateMachine::ACTION_DRAW_AND_SWAP_ABORT:
 662         // No action is actually performed, but this allows the state machine to
 663         // advance out of its waiting to draw state without actually drawing.
 664         break;
 665       case SchedulerStateMachine::ACTION_DRAW_AND_READBACK:
 666         DrawAndReadback();
 667         break;
 668       case SchedulerStateMachine::ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
 669         client_->ScheduledActionBeginOutputSurfaceCreation();
 670         break;
 671       case SchedulerStateMachine::ACTION_MANAGE_TILES:
 672         client_->ScheduledActionManageTiles();
 673         break;
 674     }
 675   } while (action != SchedulerStateMachine::ACTION_NONE);
 676
 677   SetupNextBeginFrameIfNeeded();
 678   client_->DidAnticipatedDrawTimeChange(AnticipatedDrawTime());
 679
 680   if (state_machine_.ShouldTriggerBeginImplFrameDeadlineEarly()) {
 681     DCHECK(!settings_.using_synchronous_renderer_compositor);
 682     ScheduleBeginImplFrameDeadline(base::TimeTicks());
 683   }
 684 }
 685
 686 bool Scheduler::WillDrawIfNeeded() const {
 687   return !state_machine_.PendingDrawsShouldBeAborted();
 688 }
 689
 690 scoped_ptr<base::Value> Scheduler::StateAsValue() const {
 691   scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue);
 692   state->Set("state_machine", state_machine_.AsValue().release());
 693
 694   scoped_ptr<base::DictionaryValue> scheduler_state(new base::DictionaryValue);
 695   scheduler_state->SetDouble(
 696       "time_until_anticipated_draw_time_ms",
 697       (AnticipatedDrawTime() - base::TimeTicks::Now()).InMillisecondsF());
 698   scheduler_state->SetDouble("vsync_interval_ms",
 699                              vsync_interval_.InMillisecondsF());
 700   scheduler_state->SetDouble("estimated_parent_draw_time_ms",
 701                              estimated_parent_draw_time_.InMillisecondsF());
 702   scheduler_state->SetBoolean("last_set_needs_begin_frame_",
 703                               last_set_needs_begin_frame_);
 704   scheduler_state->SetBoolean("begin_unthrottled_frame_posted_",
 705                               begin_unthrottled_frame_posted_);
 706   scheduler_state->SetBoolean("begin_retro_frame_posted_",
 707                               begin_retro_frame_posted_);
 708   scheduler_state->SetInteger("begin_retro_frame_args_",
 709                               begin_retro_frame_args_.size());
 710   scheduler_state->SetBoolean("begin_impl_frame_deadline_task_",
 711                               !begin_impl_frame_deadline_task_.IsCancelled());
 712   scheduler_state->SetBoolean("poll_for_draw_triggers_task_",
 713                               !poll_for_draw_triggers_task_.IsCancelled());
 714   scheduler_state->SetBoolean("advance_commit_state_task_",
 715                               !advance_commit_state_task_.IsCancelled());
 716   state->Set("scheduler_state", scheduler_state.release());
 717
 718   scoped_ptr<base::DictionaryValue> client_state(new base::DictionaryValue);
 719   client_state->SetDouble("draw_duration_estimate_ms",
 720                           client_->DrawDurationEstimate().InMillisecondsF());
 721   client_state->SetDouble(
 722       "begin_main_frame_to_commit_duration_estimate_ms",
 723       client_->BeginMainFrameToCommitDurationEstimate().InMillisecondsF());
 724   client_state->SetDouble(
 725       "commit_to_activate_duration_estimate_ms",
 726       client_->CommitToActivateDurationEstimate().InMillisecondsF());
 727   state->Set("client_state", client_state.release());
 728   return state.PassAs<base::Value>();
 729 }
 730
 731 bool Scheduler::CanCommitAndActivateBeforeDeadline() const {
 732   // Check if the main thread computation and commit can be finished before the
 733   // impl thread's deadline.
 734   base::TimeTicks estimated_draw_time =
 735       begin_impl_frame_args_.frame_time +
 736       client_->BeginMainFrameToCommitDurationEstimate() +
 737       client_->CommitToActivateDurationEstimate();
 738
 739   TRACE_EVENT2(
 740       TRACE_DISABLED_BY_DEFAULT("cc.debug.scheduler"),
 741       "CanCommitAndActivateBeforeDeadline",
 742       "time_left_after_drawing_ms",
 743       (begin_impl_frame_args_.deadline - estimated_draw_time).InMillisecondsF(),
 744       "state",
 745       TracedValue::FromValue(StateAsValue().release()));
 746
 747   return estimated_draw_time < begin_impl_frame_args_.deadline;
 748 }
 749
 750 bool Scheduler::IsBeginMainFrameSentOrStarted() const {
 751   return (state_machine_.commit_state() ==
 752               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_SENT ||
 753           state_machine_.commit_state() ==
 754               SchedulerStateMachine::COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED);
 755 }
 756
 757 }  // namespace cc