cc/scheduler/scheduler_state_machine.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_state_machine.h"
   6
   7 #include "base/format_macros.h"
   8 #include "base/logging.h"
   9 #include "base/strings/stringprintf.h"
  10 #include "base/trace_event/trace_event.h"
  11 #include "base/trace_event/trace_event_argument.h"
  12 #include "base/values.h"
  13
  14 namespace cc {
  15
  16 SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& settings)
  17     : settings_(settings),
  18       output_surface_state_(OUTPUT_SURFACE_LOST),
  19       begin_impl_frame_state_(BEGIN_IMPL_FRAME_STATE_IDLE),
  20       commit_state_(COMMIT_STATE_IDLE),
  21       forced_redraw_state_(FORCED_REDRAW_STATE_IDLE),
  22       commit_count_(0),
  23       current_frame_number_(0),
  24       last_frame_number_animate_performed_(-1),
  25       last_frame_number_swap_performed_(-1),
  26       last_frame_number_swap_requested_(-1),
  27       last_frame_number_begin_main_frame_sent_(-1),
  28       last_frame_number_invalidate_output_surface_performed_(-1),
  29       animate_funnel_(false),
  30       request_swap_funnel_(false),
  31       send_begin_main_frame_funnel_(false),
  32       invalidate_output_surface_funnel_(false),
  33       prepare_tiles_funnel_(0),
  34       consecutive_checkerboard_animations_(0),
  35       max_pending_swaps_(1),
  36       pending_swaps_(0),
  37       swaps_with_current_output_surface_(0),
  38       needs_redraw_(false),
  39       needs_animate_(false),
  40       needs_prepare_tiles_(false),
  41       needs_commit_(false),
  42       visible_(false),
  43       can_start_(false),
  44       can_draw_(false),
  45       has_pending_tree_(false),
  46       pending_tree_is_ready_for_activation_(false),
  47       active_tree_needs_first_draw_(false),
  48       did_create_and_initialize_first_output_surface_(false),
  49       impl_latency_takes_priority_(false),
  50       skip_next_begin_main_frame_to_reduce_latency_(false),
  51       skip_begin_main_frame_to_reduce_latency_(false),
  52       continuous_painting_(false),
  53       children_need_begin_frames_(false),
  54       defer_commits_(false),
  55       video_needs_begin_frames_(false),
  56       last_commit_had_no_updates_(false),
  57       wait_for_active_tree_ready_to_draw_(false),
  58       did_request_swap_in_last_frame_(false),
  59       did_perform_swap_in_last_draw_(false) {
  60 }
  61
  62 const char* SchedulerStateMachine::OutputSurfaceStateToString(
  63     OutputSurfaceState state) {
  64   switch (state) {
  65     case OUTPUT_SURFACE_ACTIVE:
  66       return "OUTPUT_SURFACE_ACTIVE";
  67     case OUTPUT_SURFACE_LOST:
  68       return "OUTPUT_SURFACE_LOST";
  69     case OUTPUT_SURFACE_CREATING:
  70       return "OUTPUT_SURFACE_CREATING";
  71     case OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT:
  72       return "OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT";
  73     case OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION:
  74       return "OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION";
  75   }
  76   NOTREACHED();
  77   return "???";
  78 }
  79
  80 const char* SchedulerStateMachine::BeginImplFrameStateToString(
  81     BeginImplFrameState state) {
  82   switch (state) {
  83     case BEGIN_IMPL_FRAME_STATE_IDLE:
  84       return "BEGIN_IMPL_FRAME_STATE_IDLE";
  85     case BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING:
  86       return "BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING";
  87     case BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME:
  88       return "BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME";
  89     case BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE:
  90       return "BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE";
  91   }
  92   NOTREACHED();
  93   return "???";
  94 }
  95
  96 const char* SchedulerStateMachine::BeginImplFrameDeadlineModeToString(
  97     BeginImplFrameDeadlineMode mode) {
  98   switch (mode) {
  99     case BEGIN_IMPL_FRAME_DEADLINE_MODE_NONE:
 100       return "BEGIN_IMPL_FRAME_DEADLINE_MODE_NONE";
 101     case BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE:
 102       return "BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE";
 103     case BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR:
 104       return "BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR";
 105     case BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE:
 106       return "BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE";
 107     case BEGIN_IMPL_FRAME_DEADLINE_MODE_BLOCKED_ON_READY_TO_DRAW:
 108       return "BEGIN_IMPL_FRAME_DEADLINE_MODE_BLOCKED_ON_READY_TO_DRAW";
 109   }
 110   NOTREACHED();
 111   return "???";
 112 }
 113
 114 const char* SchedulerStateMachine::CommitStateToString(CommitState state) {
 115   switch (state) {
 116     case COMMIT_STATE_IDLE:
 117       return "COMMIT_STATE_IDLE";
 118     case COMMIT_STATE_BEGIN_MAIN_FRAME_SENT:
 119       return "COMMIT_STATE_BEGIN_MAIN_FRAME_SENT";
 120     case COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED:
 121       return "COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED";
 122     case COMMIT_STATE_READY_TO_COMMIT:
 123       return "COMMIT_STATE_READY_TO_COMMIT";
 124     case COMMIT_STATE_WAITING_FOR_ACTIVATION:
 125       return "COMMIT_STATE_WAITING_FOR_ACTIVATION";
 126     case COMMIT_STATE_WAITING_FOR_DRAW:
 127       return "COMMIT_STATE_WAITING_FOR_DRAW";
 128   }
 129   NOTREACHED();
 130   return "???";
 131 }
 132
 133 const char* SchedulerStateMachine::ForcedRedrawOnTimeoutStateToString(
 134     ForcedRedrawOnTimeoutState state) {
 135   switch (state) {
 136     case FORCED_REDRAW_STATE_IDLE:
 137       return "FORCED_REDRAW_STATE_IDLE";
 138     case FORCED_REDRAW_STATE_WAITING_FOR_COMMIT:
 139       return "FORCED_REDRAW_STATE_WAITING_FOR_COMMIT";
 140     case FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION:
 141       return "FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION";
 142     case FORCED_REDRAW_STATE_WAITING_FOR_DRAW:
 143       return "FORCED_REDRAW_STATE_WAITING_FOR_DRAW";
 144   }
 145   NOTREACHED();
 146   return "???";
 147 }
 148
 149 const char* SchedulerStateMachine::ActionToString(Action action) {
 150   switch (action) {
 151     case ACTION_NONE:
 152       return "ACTION_NONE";
 153     case ACTION_ANIMATE:
 154       return "ACTION_ANIMATE";
 155     case ACTION_SEND_BEGIN_MAIN_FRAME:
 156       return "ACTION_SEND_BEGIN_MAIN_FRAME";
 157     case ACTION_COMMIT:
 158       return "ACTION_COMMIT";
 159     case ACTION_ACTIVATE_SYNC_TREE:
 160       return "ACTION_ACTIVATE_SYNC_TREE";
 161     case ACTION_DRAW_AND_SWAP_IF_POSSIBLE:
 162       return "ACTION_DRAW_AND_SWAP_IF_POSSIBLE";
 163     case ACTION_DRAW_AND_SWAP_FORCED:
 164       return "ACTION_DRAW_AND_SWAP_FORCED";
 165     case ACTION_DRAW_AND_SWAP_ABORT:
 166       return "ACTION_DRAW_AND_SWAP_ABORT";
 167     case ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
 168       return "ACTION_BEGIN_OUTPUT_SURFACE_CREATION";
 169     case ACTION_PREPARE_TILES:
 170       return "ACTION_PREPARE_TILES";
 171     case ACTION_INVALIDATE_OUTPUT_SURFACE:
 172       return "ACTION_INVALIDATE_OUTPUT_SURFACE";
 173   }
 174   NOTREACHED();
 175   return "???";
 176 }
 177
 178 scoped_refptr<base::trace_event::ConvertableToTraceFormat>
 179 SchedulerStateMachine::AsValue() const {
 180   scoped_refptr<base::trace_event::TracedValue> state =
 181       new base::trace_event::TracedValue();
 182   AsValueInto(state.get());
 183   return state;
 184 }
 185
 186 void SchedulerStateMachine::AsValueInto(
 187     base::trace_event::TracedValue* state) const {
 188   state->BeginDictionary("major_state");
 189   state->SetString("next_action", ActionToString(NextAction()));
 190   state->SetString("begin_impl_frame_state",
 191                    BeginImplFrameStateToString(begin_impl_frame_state_));
 192   state->SetString("commit_state", CommitStateToString(commit_state_));
 193   state->SetString("output_surface_state_",
 194                    OutputSurfaceStateToString(output_surface_state_));
 195   state->SetString("forced_redraw_state",
 196                    ForcedRedrawOnTimeoutStateToString(forced_redraw_state_));
 197   state->EndDictionary();
 198
 199   state->BeginDictionary("minor_state");
 200   state->SetInteger("commit_count", commit_count_);
 201   state->SetInteger("current_frame_number", current_frame_number_);
 202   state->SetInteger("last_frame_number_animate_performed",
 203                     last_frame_number_animate_performed_);
 204   state->SetInteger("last_frame_number_swap_performed",
 205                     last_frame_number_swap_performed_);
 206   state->SetInteger("last_frame_number_swap_requested",
 207                     last_frame_number_swap_requested_);
 208   state->SetInteger("last_frame_number_begin_main_frame_sent",
 209                     last_frame_number_begin_main_frame_sent_);
 210   state->SetBoolean("funnel: animate_funnel", animate_funnel_);
 211   state->SetBoolean("funnel: request_swap_funnel", request_swap_funnel_);
 212   state->SetBoolean("funnel: send_begin_main_frame_funnel",
 213                     send_begin_main_frame_funnel_);
 214   state->SetInteger("funnel: prepare_tiles_funnel", prepare_tiles_funnel_);
 215   state->SetBoolean("funnel: invalidate_output_surface_funnel",
 216                     invalidate_output_surface_funnel_);
 217   state->SetInteger("consecutive_checkerboard_animations",
 218                     consecutive_checkerboard_animations_);
 219   state->SetInteger("max_pending_swaps_", max_pending_swaps_);
 220   state->SetInteger("pending_swaps_", pending_swaps_);
 221   state->SetInteger("swaps_with_current_output_surface",
 222                     swaps_with_current_output_surface_);
 223   state->SetBoolean("needs_redraw", needs_redraw_);
 224   state->SetBoolean("needs_animate_", needs_animate_);
 225   state->SetBoolean("needs_prepare_tiles", needs_prepare_tiles_);
 226   state->SetBoolean("needs_commit", needs_commit_);
 227   state->SetBoolean("visible", visible_);
 228   state->SetBoolean("can_start", can_start_);
 229   state->SetBoolean("can_draw", can_draw_);
 230   state->SetBoolean("has_pending_tree", has_pending_tree_);
 231   state->SetBoolean("pending_tree_is_ready_for_activation",
 232                     pending_tree_is_ready_for_activation_);
 233   state->SetBoolean("active_tree_needs_first_draw",
 234                     active_tree_needs_first_draw_);
 235   state->SetBoolean("wait_for_active_tree_ready_to_draw",
 236                     wait_for_active_tree_ready_to_draw_);
 237   state->SetBoolean("did_create_and_initialize_first_output_surface",
 238                     did_create_and_initialize_first_output_surface_);
 239   state->SetBoolean("impl_latency_takes_priority",
 240                     impl_latency_takes_priority_);
 241   state->SetBoolean("main_thread_is_in_high_latency_mode",
 242                     MainThreadIsInHighLatencyMode());
 243   state->SetBoolean("skip_begin_main_frame_to_reduce_latency",
 244                     skip_begin_main_frame_to_reduce_latency_);
 245   state->SetBoolean("skip_next_begin_main_frame_to_reduce_latency",
 246                     skip_next_begin_main_frame_to_reduce_latency_);
 247   state->SetBoolean("continuous_painting", continuous_painting_);
 248   state->SetBoolean("children_need_begin_frames", children_need_begin_frames_);
 249   state->SetBoolean("video_needs_begin_frames", video_needs_begin_frames_);
 250   state->SetBoolean("defer_commits", defer_commits_);
 251   state->SetBoolean("last_commit_had_no_updates", last_commit_had_no_updates_);
 252   state->SetBoolean("did_request_swap_in_last_frame",
 253                     did_request_swap_in_last_frame_);
 254   state->SetBoolean("did_perform_swap_in_last_draw",
 255                     did_perform_swap_in_last_draw_);
 256   state->EndDictionary();
 257 }
 258
 259 bool SchedulerStateMachine::PendingDrawsShouldBeAborted() const {
 260   // These are all the cases where we normally cannot or do not want to draw
 261   // but, if needs_redraw_ is true and we do not draw to make forward progress,
 262   // we might deadlock with the main thread.
 263   // This should be a superset of PendingActivationsShouldBeForced() since
 264   // activation of the pending tree is blocked by drawing of the active tree and
 265   // the main thread might be blocked on activation of the most recent commit.
 266   if (PendingActivationsShouldBeForced())
 267     return true;
 268
 269   // Additional states where we should abort draws.
 270   if (!can_draw_)
 271     return true;
 272   return false;
 273 }
 274
 275 bool SchedulerStateMachine::PendingActivationsShouldBeForced() const {
 276   // There is no output surface to trigger our activations.
 277   // If we do not force activations to make forward progress, we might deadlock
 278   // with the main thread.
 279   if (output_surface_state_ == OUTPUT_SURFACE_LOST)
 280     return true;
 281
 282   // If we're not visible, we should force activation.
 283   // Since we set RequiresHighResToDraw when becoming visible, we ensure that we
 284   // don't checkerboard until all visible resources are done. Furthermore, if we
 285   // do keep the pending tree around, when becoming visible we might activate
 286   // prematurely causing RequiresHighResToDraw flag to be reset. In all cases,
 287   // we can simply activate on becoming invisible since we don't need to draw
 288   // the active tree when we're in this state.
 289   if (!visible_)
 290     return true;
 291
 292   return false;
 293 }
 294
 295 bool SchedulerStateMachine::ShouldBeginOutputSurfaceCreation() const {
 296   // Don't try to initialize too early.
 297   if (!can_start_)
 298     return false;
 299
 300   // We only want to start output surface initialization after the
 301   // previous commit is complete.
 302   if (commit_state_ != COMMIT_STATE_IDLE)
 303     return false;
 304
 305   // Make sure the BeginImplFrame from any previous OutputSurfaces
 306   // are complete before creating the new OutputSurface.
 307   if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_IDLE)
 308     return false;
 309
 310   // We want to clear the pipeline of any pending draws and activations
 311   // before starting output surface initialization. This allows us to avoid
 312   // weird corner cases where we abort draws or force activation while we
 313   // are initializing the output surface.
 314   if (active_tree_needs_first_draw_ || has_pending_tree_)
 315     return false;
 316
 317   // We need to create the output surface if we don't have one and we haven't
 318   // started creating one yet.
 319   return output_surface_state_ == OUTPUT_SURFACE_LOST;
 320 }
 321
 322 bool SchedulerStateMachine::ShouldDraw() const {
 323   // If we need to abort draws, we should do so ASAP since the draw could
 324   // be blocking other important actions (like output surface initialization),
 325   // from occurring. If we are waiting for the first draw, then perform the
 326   // aborted draw to keep things moving. If we are not waiting for the first
 327   // draw however, we don't want to abort for no reason.
 328   if (PendingDrawsShouldBeAborted())
 329     return active_tree_needs_first_draw_;
 330
 331   // Do not draw too many times in a single frame. It's okay that we don't check
 332   // this before checking for aborted draws because aborted draws do not request
 333   // a swap.
 334   if (request_swap_funnel_)
 335     return false;
 336
 337   // Don't draw if we are waiting on the first commit after a surface.
 338   if (output_surface_state_ != OUTPUT_SURFACE_ACTIVE)
 339     return false;
 340
 341   // Do not queue too many swaps.
 342   if (pending_swaps_ >= max_pending_swaps_)
 343     return false;
 344
 345   // Except for the cases above, do not draw outside of the BeginImplFrame
 346   // deadline.
 347   if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
 348     return false;
 349
 350   // Only handle forced redraws due to timeouts on the regular deadline.
 351   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
 352     return true;
 353
 354   return needs_redraw_;
 355 }
 356
 357 bool SchedulerStateMachine::ShouldActivatePendingTree() const {
 358   // There is nothing to activate.
 359   if (!has_pending_tree_)
 360     return false;
 361
 362   // We should not activate a second tree before drawing the first one.
 363   // Even if we need to force activation of the pending tree, we should abort
 364   // drawing the active tree first.
 365   if (active_tree_needs_first_draw_)
 366     return false;
 367
 368   // If we want to force activation, do so ASAP.
 369   if (PendingActivationsShouldBeForced())
 370     return true;
 371
 372   // At this point, only activate if we are ready to activate.
 373   return pending_tree_is_ready_for_activation_;
 374 }
 375
 376 bool SchedulerStateMachine::ShouldAnimate() const {
 377   // Do not animate too many times in a single frame.
 378   if (animate_funnel_)
 379     return false;
 380
 381   // Don't animate if we are waiting on the first commit after a surface.
 382   if (output_surface_state_ != OUTPUT_SURFACE_ACTIVE)
 383     return false;
 384
 385   if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING &&
 386       begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
 387     return false;
 388
 389   return needs_redraw_ || needs_animate_;
 390 }
 391
 392 bool SchedulerStateMachine::CouldSendBeginMainFrame() const {
 393   if (!needs_commit_)
 394     return false;
 395
 396   // We can not perform commits if we are not visible.
 397   if (!visible_)
 398     return false;
 399
 400   // Do not make a new commits when it is deferred.
 401   if (defer_commits_)
 402     return false;
 403
 404   return true;
 405 }
 406
 407 bool SchedulerStateMachine::SendingBeginMainFrameMightCauseDeadlock() const {
 408   // NPAPI is the only case where the UI thread makes synchronous calls to the
 409   // Renderer main thread. During that synchronous call, we may not get a
 410   // SwapAck for the UI thread, which may prevent BeginMainFrame's from
 411   // completing if there's enough back pressure. If the BeginMainFrame can't
 412   // make progress, the Renderer can't service the UI thread's synchronous call
 413   // and we have deadlock.
 414   // This returns true if there's too much backpressure to finish a commit
 415   // if we were to initiate a BeginMainFrame.
 416   return has_pending_tree_ && active_tree_needs_first_draw_ &&
 417          pending_swaps_ >= max_pending_swaps_;
 418 }
 419
 420 bool SchedulerStateMachine::ShouldSendBeginMainFrame() const {
 421   if (!CouldSendBeginMainFrame())
 422     return false;
 423
 424   // Do not send begin main frame too many times in a single frame.
 425   if (send_begin_main_frame_funnel_)
 426     return false;
 427
 428   // Only send BeginMainFrame when there isn't another commit pending already.
 429   // Other parts of the state machine indirectly defer the BeginMainFrame
 430   // by transitioning to WAITING commit states rather than going
 431   // immediately to IDLE.
 432   if (commit_state_ != COMMIT_STATE_IDLE)
 433     return false;
 434
 435   // Don't send BeginMainFrame early if we are prioritizing the active tree
 436   // because of impl_latency_takes_priority_.
 437   if (impl_latency_takes_priority_ &&
 438       (has_pending_tree_ || active_tree_needs_first_draw_)) {
 439     return false;
 440   }
 441
 442   // We should not send BeginMainFrame while we are in
 443   // BEGIN_IMPL_FRAME_STATE_IDLE since we might have new
 444   // user input arriving soon.
 445   // TODO(brianderson): Allow sending BeginMainFrame while idle when the main
 446   // thread isn't consuming user input.
 447   if (begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_IDLE &&
 448       BeginFrameNeeded())
 449     return false;
 450
 451   // We need a new commit for the forced redraw. This honors the
 452   // single commit per interval because the result will be swapped to screen.
 453   // TODO(brianderson): Remove this or move it below the
 454   // SendingBeginMainFrameMightCauseDeadlock check since  we want to avoid
 455   // ever returning true from this method if we might cause deadlock.
 456   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT)
 457     return true;
 458
 459   // We shouldn't normally accept commits if there isn't an OutputSurface.
 460   if (!HasInitializedOutputSurface())
 461     return false;
 462
 463   // Make sure the BeginMainFrame can finish eventually if we start it.
 464   if (SendingBeginMainFrameMightCauseDeadlock())
 465     return false;
 466
 467   if (!settings_.main_frame_while_swap_throttled_enabled) {
 468     // SwapAck throttle the BeginMainFrames unless we just swapped to
 469     // potentially improve impl-thread latency over main-thread throughput.
 470     // TODO(brianderson): Remove this restriction to improve throughput or
 471     // make it conditional on impl_latency_takes_priority_.
 472     bool just_swapped_in_deadline =
 473         begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE &&
 474         did_perform_swap_in_last_draw_;
 475     if (pending_swaps_ >= max_pending_swaps_ && !just_swapped_in_deadline)
 476       return false;
 477   }
 478
 479   if (skip_begin_main_frame_to_reduce_latency_)
 480     return false;
 481
 482   return true;
 483 }
 484
 485 bool SchedulerStateMachine::ShouldCommit() const {
 486   if (commit_state_ != COMMIT_STATE_READY_TO_COMMIT)
 487     return false;
 488
 489   // We must not finish the commit until the pending tree is free.
 490   if (has_pending_tree_) {
 491     DCHECK(settings_.main_frame_before_activation_enabled);
 492     return false;
 493   }
 494
 495   // If we only have an active tree, it is incorrect to replace it
 496   // before we've drawn it.
 497   DCHECK_IMPLIES(settings_.commit_to_active_tree,
 498                  !active_tree_needs_first_draw_);
 499
 500   return true;
 501 }
 502
 503 bool SchedulerStateMachine::ShouldPrepareTiles() const {
 504   // PrepareTiles only really needs to be called immediately after commit
 505   // and then periodically after that. Use a funnel to make sure we average
 506   // one PrepareTiles per BeginImplFrame in the long run.
 507   if (prepare_tiles_funnel_ > 0)
 508     return false;
 509
 510   // Limiting to once per-frame is not enough, since we only want to
 511   // prepare tiles _after_ draws.
 512   if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
 513     return false;
 514
 515   return needs_prepare_tiles_;
 516 }
 517
 518 bool SchedulerStateMachine::ShouldInvalidateOutputSurface() const {
 519   // Do not invalidate too many times in a frame.
 520   if (invalidate_output_surface_funnel_)
 521     return false;
 522
 523   // Only the synchronous compositor requires invalidations.
 524   if (!settings_.using_synchronous_renderer_compositor)
 525     return false;
 526
 527   // Invalidations are only performed inside a BeginFrame.
 528   if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING)
 529     return false;
 530
 531   // TODO(sunnyps): needs_prepare_tiles_ is needed here because PrepareTiles is
 532   // called only inside the deadline / draw phase. We could remove this if we
 533   // allowed PrepareTiles to happen in OnBeginImplFrame.
 534   return needs_redraw_ || needs_prepare_tiles_;
 535 }
 536
 537 SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
 538   if (ShouldActivatePendingTree())
 539     return ACTION_ACTIVATE_SYNC_TREE;
 540   if (ShouldCommit())
 541     return ACTION_COMMIT;
 542   if (ShouldAnimate())
 543     return ACTION_ANIMATE;
 544   if (ShouldDraw()) {
 545     if (PendingDrawsShouldBeAborted())
 546       return ACTION_DRAW_AND_SWAP_ABORT;
 547     else if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
 548       return ACTION_DRAW_AND_SWAP_FORCED;
 549     else
 550       return ACTION_DRAW_AND_SWAP_IF_POSSIBLE;
 551   }
 552   if (ShouldPrepareTiles())
 553     return ACTION_PREPARE_TILES;
 554   if (ShouldSendBeginMainFrame())
 555     return ACTION_SEND_BEGIN_MAIN_FRAME;
 556   if (ShouldInvalidateOutputSurface())
 557     return ACTION_INVALIDATE_OUTPUT_SURFACE;
 558   if (ShouldBeginOutputSurfaceCreation())
 559     return ACTION_BEGIN_OUTPUT_SURFACE_CREATION;
 560   return ACTION_NONE;
 561 }
 562
 563 void SchedulerStateMachine::UpdateState(Action action) {
 564   switch (action) {
 565     case ACTION_NONE:
 566       return;
 567
 568     case ACTION_ACTIVATE_SYNC_TREE:
 569       UpdateStateOnActivation();
 570       return;
 571
 572     case ACTION_ANIMATE:
 573       UpdateStateOnAnimate();
 574       return;
 575
 576     case ACTION_SEND_BEGIN_MAIN_FRAME:
 577       UpdateStateOnSendBeginMainFrame();
 578       return;
 579
 580     case ACTION_COMMIT: {
 581       bool commit_has_no_updates = false;
 582       UpdateStateOnCommit(commit_has_no_updates);
 583       return;
 584     }
 585
 586     case ACTION_DRAW_AND_SWAP_FORCED:
 587     case ACTION_DRAW_AND_SWAP_IF_POSSIBLE: {
 588       bool did_request_swap = true;
 589       UpdateStateOnDraw(did_request_swap);
 590       return;
 591     }
 592
 593     case ACTION_DRAW_AND_SWAP_ABORT: {
 594       bool did_request_swap = false;
 595       UpdateStateOnDraw(did_request_swap);
 596       return;
 597     }
 598
 599     case ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
 600       UpdateStateOnBeginOutputSurfaceCreation();
 601       return;
 602
 603     case ACTION_PREPARE_TILES:
 604       UpdateStateOnPrepareTiles();
 605       return;
 606
 607     case ACTION_INVALIDATE_OUTPUT_SURFACE:
 608       UpdateStateOnInvalidateOutputSurface();
 609       return;
 610   }
 611 }
 612
 613 void SchedulerStateMachine::UpdateStateOnAnimate() {
 614   DCHECK(!animate_funnel_);
 615   last_frame_number_animate_performed_ = current_frame_number_;
 616   animate_funnel_ = true;
 617   needs_animate_ = false;
 618   // TODO(skyostil): Instead of assuming this, require the client to tell us.
 619   SetNeedsRedraw();
 620 }
 621
 622 void SchedulerStateMachine::UpdateStateOnSendBeginMainFrame() {
 623   DCHECK(!has_pending_tree_ || settings_.main_frame_before_activation_enabled);
 624   DCHECK(visible_);
 625   DCHECK(!send_begin_main_frame_funnel_);
 626   commit_state_ = COMMIT_STATE_BEGIN_MAIN_FRAME_SENT;
 627   needs_commit_ = false;
 628   send_begin_main_frame_funnel_ = true;
 629   last_frame_number_begin_main_frame_sent_ = current_frame_number_;
 630 }
 631
 632 void SchedulerStateMachine::UpdateStateOnCommit(bool commit_has_no_updates) {
 633   commit_count_++;
 634
 635   // Animate after commit even if we've already animated.
 636   if (!commit_has_no_updates)
 637     animate_funnel_ = false;
 638
 639   if (commit_has_no_updates || settings_.main_frame_before_activation_enabled) {
 640     commit_state_ = COMMIT_STATE_IDLE;
 641   } else {
 642     commit_state_ = COMMIT_STATE_WAITING_FOR_ACTIVATION;
 643   }
 644
 645   // If the commit was aborted, then there is no pending tree.
 646   has_pending_tree_ = !commit_has_no_updates;
 647
 648   // Update state related to forced draws.
 649   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT) {
 650     forced_redraw_state_ = has_pending_tree_
 651                                ? FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION
 652                                : FORCED_REDRAW_STATE_WAITING_FOR_DRAW;
 653   }
 654
 655   // Update the output surface state.
 656   DCHECK_NE(output_surface_state_, OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION);
 657   if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT) {
 658     if (has_pending_tree_) {
 659       output_surface_state_ = OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION;
 660     } else {
 661       output_surface_state_ = OUTPUT_SURFACE_ACTIVE;
 662       needs_redraw_ = true;
 663     }
 664   }
 665
 666   // Update state if we have a new active tree to draw, or if the active tree
 667   // was unchanged but we need to do a forced draw.
 668   if (!has_pending_tree_ &&
 669       (!commit_has_no_updates ||
 670        forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)) {
 671     needs_redraw_ = true;
 672     active_tree_needs_first_draw_ = true;
 673   }
 674
 675   // This post-commit work is common to both completed and aborted commits.
 676   pending_tree_is_ready_for_activation_ = false;
 677
 678   if (continuous_painting_)
 679     needs_commit_ = true;
 680   last_commit_had_no_updates_ = commit_has_no_updates;
 681 }
 682
 683 void SchedulerStateMachine::UpdateStateOnActivation() {
 684   if (commit_state_ == COMMIT_STATE_WAITING_FOR_ACTIVATION) {
 685     commit_state_ = settings_.commit_to_active_tree
 686                         ? COMMIT_STATE_WAITING_FOR_DRAW
 687                         : COMMIT_STATE_IDLE;
 688   }
 689
 690   if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION)
 691     output_surface_state_ = OUTPUT_SURFACE_ACTIVE;
 692
 693   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION)
 694     forced_redraw_state_ = FORCED_REDRAW_STATE_WAITING_FOR_DRAW;
 695
 696   has_pending_tree_ = false;
 697   pending_tree_is_ready_for_activation_ = false;
 698   active_tree_needs_first_draw_ = true;
 699   needs_redraw_ = true;
 700 }
 701
 702 void SchedulerStateMachine::UpdateStateOnDraw(bool did_request_swap) {
 703   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
 704     forced_redraw_state_ = FORCED_REDRAW_STATE_IDLE;
 705
 706   if (commit_state_ == COMMIT_STATE_WAITING_FOR_DRAW)
 707     commit_state_ = COMMIT_STATE_IDLE;
 708
 709   needs_redraw_ = false;
 710   active_tree_needs_first_draw_ = false;
 711
 712   if (did_request_swap) {
 713     DCHECK(!request_swap_funnel_);
 714     request_swap_funnel_ = true;
 715     did_request_swap_in_last_frame_ = true;
 716     last_frame_number_swap_requested_ = current_frame_number_;
 717   }
 718 }
 719
 720 void SchedulerStateMachine::UpdateStateOnPrepareTiles() {
 721   needs_prepare_tiles_ = false;
 722 }
 723
 724 void SchedulerStateMachine::UpdateStateOnBeginOutputSurfaceCreation() {
 725   DCHECK_EQ(output_surface_state_, OUTPUT_SURFACE_LOST);
 726   output_surface_state_ = OUTPUT_SURFACE_CREATING;
 727
 728   // The following DCHECKs make sure we are in the proper quiescent state.
 729   // The pipeline should be flushed entirely before we start output
 730   // surface creation to avoid complicated corner cases.
 731   DCHECK_EQ(commit_state_, COMMIT_STATE_IDLE);
 732   DCHECK(!has_pending_tree_);
 733   DCHECK(!active_tree_needs_first_draw_);
 734 }
 735
 736 void SchedulerStateMachine::UpdateStateOnInvalidateOutputSurface() {
 737   DCHECK(!invalidate_output_surface_funnel_);
 738   invalidate_output_surface_funnel_ = true;
 739   last_frame_number_invalidate_output_surface_performed_ =
 740       current_frame_number_;
 741
 742   // The synchronous compositor makes no guarantees about a draw coming in after
 743   // an invalidate so clear any flags that would cause the compositor's pipeline
 744   // to stall.
 745   active_tree_needs_first_draw_ = false;  // blocks commit if true
 746 }
 747
 748 void SchedulerStateMachine::SetSkipNextBeginMainFrameToReduceLatency() {
 749   TRACE_EVENT_INSTANT0("cc",
 750                        "Scheduler: SkipNextBeginMainFrameToReduceLatency",
 751                        TRACE_EVENT_SCOPE_THREAD);
 752   skip_next_begin_main_frame_to_reduce_latency_ = true;
 753 }
 754
 755 bool SchedulerStateMachine::BeginFrameRequiredForChildren() const {
 756   return children_need_begin_frames_;
 757 }
 758 bool SchedulerStateMachine::BeginFrameNeededForVideo() const {
 759   return video_needs_begin_frames_;
 760 }
 761
 762 bool SchedulerStateMachine::BeginFrameNeeded() const {
 763   // We can't handle BeginFrames when output surface isn't initialized.
 764   // TODO(brianderson): Support output surface creation inside a BeginFrame.
 765   if (!HasInitializedOutputSurface())
 766     return false;
 767
 768   // If we are not visible, we don't need BeginFrame messages.
 769   if (!visible_)
 770     return false;
 771
 772   return (BeginFrameRequiredForAction() || BeginFrameRequiredForChildren() ||
 773           BeginFrameNeededForVideo() || ProactiveBeginFrameWanted());
 774 }
 775
 776 void SchedulerStateMachine::SetChildrenNeedBeginFrames(
 777     bool children_need_begin_frames) {
 778   children_need_begin_frames_ = children_need_begin_frames;
 779 }
 780
 781 void SchedulerStateMachine::SetVideoNeedsBeginFrames(
 782     bool video_needs_begin_frames) {
 783   video_needs_begin_frames_ = video_needs_begin_frames;
 784 }
 785
 786 void SchedulerStateMachine::SetDeferCommits(bool defer_commits) {
 787   defer_commits_ = defer_commits;
 788 }
 789
 790 // These are the cases where we require a BeginFrame message to make progress
 791 // on requested actions.
 792 bool SchedulerStateMachine::BeginFrameRequiredForAction() const {
 793   // The forced draw respects our normal draw scheduling, so we need to
 794   // request a BeginImplFrame for it.
 795   if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
 796     return true;
 797
 798   return needs_animate_ || needs_redraw_ || (needs_commit_ && !defer_commits_);
 799 }
 800
 801 // These are cases where we are very likely want a BeginFrame message in the
 802 // near future. Proactively requesting the BeginImplFrame helps hide the round
 803 // trip latency of the SetNeedsBeginFrame request that has to go to the
 804 // Browser.
 805 // This includes things like drawing soon, but might not actually have a new
 806 // frame to draw when we receive the next BeginImplFrame.
 807 bool SchedulerStateMachine::ProactiveBeginFrameWanted() const {
 808   // Do not be proactive when invisible.
 809   if (!visible_)
 810     return false;
 811
 812   // We should proactively request a BeginImplFrame if a commit is pending
 813   // because we will want to draw if the commit completes quickly. Do not
 814   // request frames when commits are disabled, because the frame requests will
 815   // not provide the needed commit (and will wake up the process when it could
 816   // stay idle).
 817   if ((commit_state_ != COMMIT_STATE_IDLE) && !defer_commits_)
 818     return true;
 819
 820   // If the pending tree activates quickly, we'll want a BeginImplFrame soon
 821   // to draw the new active tree.
 822   if (has_pending_tree_)
 823     return true;
 824
 825   // Changing priorities may allow us to activate (given the new priorities),
 826   // which may result in a new frame.
 827   if (needs_prepare_tiles_)
 828     return true;
 829
 830   // If we just sent a swap request, it's likely that we are going to produce
 831   // another frame soon. This helps avoid negative glitches in our
 832   // SetNeedsBeginFrame requests, which may propagate to the BeginImplFrame
 833   // provider and get sampled at an inopportune time, delaying the next
 834   // BeginImplFrame.
 835   if (did_request_swap_in_last_frame_)
 836     return true;
 837
 838   // If the last commit was aborted because of early out (no updates), we should
 839   // still want a begin frame in case there is a commit coming again.
 840   if (last_commit_had_no_updates_)
 841     return true;
 842
 843   return false;
 844 }
 845
 846 void SchedulerStateMachine::OnBeginImplFrame() {
 847   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING;
 848   current_frame_number_++;
 849
 850   last_commit_had_no_updates_ = false;
 851   did_request_swap_in_last_frame_ = false;
 852
 853   // Clear funnels for any actions we perform during the frame.
 854   animate_funnel_ = false;
 855   send_begin_main_frame_funnel_ = false;
 856   invalidate_output_surface_funnel_ = false;
 857
 858   // "Drain" the PrepareTiles funnel.
 859   if (prepare_tiles_funnel_ > 0)
 860     prepare_tiles_funnel_--;
 861
 862   skip_begin_main_frame_to_reduce_latency_ =
 863       skip_next_begin_main_frame_to_reduce_latency_;
 864   skip_next_begin_main_frame_to_reduce_latency_ = false;
 865 }
 866
 867 void SchedulerStateMachine::OnBeginImplFrameDeadlinePending() {
 868   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME;
 869 }
 870
 871 void SchedulerStateMachine::OnBeginImplFrameDeadline() {
 872   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE;
 873
 874   did_perform_swap_in_last_draw_ = false;
 875
 876   // Clear funnels for any actions we perform during the deadline.
 877   request_swap_funnel_ = false;
 878
 879   // Allow one PrepareTiles per draw for synchronous compositor.
 880   if (settings_.using_synchronous_renderer_compositor) {
 881     if (prepare_tiles_funnel_ > 0)
 882       prepare_tiles_funnel_--;
 883   }
 884 }
 885
 886 void SchedulerStateMachine::OnBeginImplFrameIdle() {
 887   begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_IDLE;
 888 }
 889
 890 SchedulerStateMachine::BeginImplFrameDeadlineMode
 891 SchedulerStateMachine::CurrentBeginImplFrameDeadlineMode() const {
 892   if (settings_.using_synchronous_renderer_compositor) {
 893     // No deadline for synchronous compositor.
 894     return BEGIN_IMPL_FRAME_DEADLINE_MODE_NONE;
 895   } else if (wait_for_active_tree_ready_to_draw_) {
 896     // When we are waiting for ready to draw signal, we do not wait to post a
 897     // deadline yet.
 898     return BEGIN_IMPL_FRAME_DEADLINE_MODE_BLOCKED_ON_READY_TO_DRAW;
 899   } else if (ShouldTriggerBeginImplFrameDeadlineImmediately()) {
 900     return BEGIN_IMPL_FRAME_DEADLINE_MODE_IMMEDIATE;
 901   } else if (needs_redraw_ && pending_swaps_ < max_pending_swaps_) {
 902     // We have an animation or fast input path on the impl thread that wants
 903     // to draw, so don't wait too long for a new active tree.
 904     // If we are swap throttled we should wait until we are unblocked.
 905     return BEGIN_IMPL_FRAME_DEADLINE_MODE_REGULAR;
 906   } else {
 907     // The impl thread doesn't have anything it wants to draw and we are just
 908     // waiting for a new active tree or we are swap throttled. In short we are
 909     // blocked.
 910     return BEGIN_IMPL_FRAME_DEADLINE_MODE_LATE;
 911   }
 912 }
 913
 914 bool SchedulerStateMachine::ShouldTriggerBeginImplFrameDeadlineImmediately()
 915     const {
 916   // TODO(brianderson): This should take into account multiple commit sources.
 917   if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME)
 918     return false;
 919
 920   // If we just forced activation, we should end the deadline right now.
 921   if (PendingActivationsShouldBeForced() && !has_pending_tree_)
 922     return true;
 923
 924   // SwapAck throttle the deadline since we wont draw and swap anyway.
 925   if (pending_swaps_ >= max_pending_swaps_)
 926     return false;
 927
 928   if (active_tree_needs_first_draw_)
 929     return true;
 930
 931   if (!needs_redraw_)
 932     return false;
 933
 934   // This is used to prioritize impl-thread draws when the main thread isn't
 935   // producing anything, e.g., after an aborted commit. We also check that we
 936   // don't have a pending tree -- otherwise we should give it a chance to
 937   // activate.
 938   // TODO(skyostil): Revisit this when we have more accurate deadline estimates.
 939   if (commit_state_ == COMMIT_STATE_IDLE && !has_pending_tree_)
 940     return true;
 941
 942   // Prioritize impl-thread draws in impl_latency_takes_priority_ mode.
 943   if (impl_latency_takes_priority_)
 944     return true;
 945
 946   return false;
 947 }
 948
 949 bool SchedulerStateMachine::MainThreadIsInHighLatencyMode() const {
 950   // If a commit is pending before the previous commit has been drawn, we
 951   // are definitely in a high latency mode.
 952   if (CommitPending() && (active_tree_needs_first_draw_ || has_pending_tree_))
 953     return true;
 954
 955   // If we just sent a BeginMainFrame and haven't hit the deadline yet, the main
 956   // thread is in a low latency mode.
 957   if (send_begin_main_frame_funnel_ &&
 958       (begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING ||
 959        begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME))
 960     return false;
 961
 962   // If there's a commit in progress it must either be from the previous frame
 963   // or it started after the impl thread's deadline. In either case the main
 964   // thread is in high latency mode.
 965   if (CommitPending())
 966     return true;
 967
 968   // Similarly, if there's a pending tree the main thread is in high latency
 969   // mode, because either
 970   //   it's from the previous frame
 971   // or
 972   //   we're currently drawing the active tree and the pending tree will thus
 973   //   only be drawn in the next frame.
 974   if (has_pending_tree_)
 975     return true;
 976
 977   if (begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE) {
 978     // Even if there's a new active tree to draw at the deadline or we've just
 979     // swapped it, it may have been triggered by a previous BeginImplFrame, in
 980     // which case the main thread is in a high latency mode.
 981     return (active_tree_needs_first_draw_ || did_perform_swap_in_last_draw_) &&
 982            !send_begin_main_frame_funnel_;
 983   }
 984
 985   // If the active tree needs its first draw in any other state, we know the
 986   // main thread is in a high latency mode.
 987   return active_tree_needs_first_draw_;
 988 }
 989
 990 void SchedulerStateMachine::SetVisible(bool visible) { visible_ = visible; }
 991
 992 void SchedulerStateMachine::SetCanDraw(bool can_draw) { can_draw_ = can_draw; }
 993
 994 void SchedulerStateMachine::SetNeedsRedraw() { needs_redraw_ = true; }
 995
 996 void SchedulerStateMachine::SetNeedsAnimate() {
 997   needs_animate_ = true;
 998 }
 999
1000 void SchedulerStateMachine::SetWaitForReadyToDraw() {
1001   wait_for_active_tree_ready_to_draw_ = true;
1002 }
1003
1004 void SchedulerStateMachine::SetNeedsPrepareTiles() {
1005   if (!needs_prepare_tiles_) {
1006     TRACE_EVENT0("cc", "SchedulerStateMachine::SetNeedsPrepareTiles");
1007     needs_prepare_tiles_ = true;
1008   }
1009 }
1010
1011 void SchedulerStateMachine::SetMaxSwapsPending(int max) {
1012   max_pending_swaps_ = max;
1013 }
1014
1015 void SchedulerStateMachine::DidSwapBuffers() {
1016   pending_swaps_++;
1017   swaps_with_current_output_surface_++;
1018
1019   DCHECK_LE(pending_swaps_, max_pending_swaps_);
1020
1021   did_perform_swap_in_last_draw_ = true;
1022   last_frame_number_swap_performed_ = current_frame_number_;
1023 }
1024
1025 void SchedulerStateMachine::DidSwapBuffersComplete() {
1026   pending_swaps_--;
1027 }
1028
1029 void SchedulerStateMachine::SetImplLatencyTakesPriority(
1030     bool impl_latency_takes_priority) {
1031   impl_latency_takes_priority_ = impl_latency_takes_priority;
1032 }
1033
1034 void SchedulerStateMachine::DidDrawIfPossibleCompleted(DrawResult result) {
1035   switch (result) {
1036     case INVALID_RESULT:
1037       NOTREACHED() << "Uninitialized DrawResult.";
1038       break;
1039     case DRAW_ABORTED_CANT_DRAW:
1040     case DRAW_ABORTED_CONTEXT_LOST:
1041       NOTREACHED() << "Invalid return value from DrawAndSwapIfPossible:"
1042                    << result;
1043       break;
1044     case DRAW_SUCCESS:
1045       consecutive_checkerboard_animations_ = 0;
1046       forced_redraw_state_ = FORCED_REDRAW_STATE_IDLE;
1047       break;
1048     case DRAW_ABORTED_CHECKERBOARD_ANIMATIONS:
1049       needs_redraw_ = true;
1050
1051       // If we're already in the middle of a redraw, we don't need to
1052       // restart it.
1053       if (forced_redraw_state_ != FORCED_REDRAW_STATE_IDLE)
1054         return;
1055
1056       needs_commit_ = true;
1057       consecutive_checkerboard_animations_++;
1058       if (settings_.timeout_and_draw_when_animation_checkerboards &&
1059           consecutive_checkerboard_animations_ >=
1060               settings_.maximum_number_of_failed_draws_before_draw_is_forced) {
1061         consecutive_checkerboard_animations_ = 0;
1062         // We need to force a draw, but it doesn't make sense to do this until
1063         // we've committed and have new textures.
1064         forced_redraw_state_ = FORCED_REDRAW_STATE_WAITING_FOR_COMMIT;
1065       }
1066       break;
1067     case DRAW_ABORTED_MISSING_HIGH_RES_CONTENT:
1068       // It's not clear whether this missing content is because of missing
1069       // pictures (which requires a commit) or because of memory pressure
1070       // removing textures (which might not).  To be safe, request a commit
1071       // anyway.
1072       needs_commit_ = true;
1073       break;
1074   }
1075 }
1076
1077 void SchedulerStateMachine::SetNeedsCommit() {
1078   needs_commit_ = true;
1079 }
1080
1081 void SchedulerStateMachine::NotifyReadyToCommit() {
1082   DCHECK(commit_state_ == COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED)
1083       << AsValue()->ToString();
1084   commit_state_ = COMMIT_STATE_READY_TO_COMMIT;
1085   // In commit_to_active_tree mode, commit should happen right after
1086   // BeginFrame, meaning when this function is called, next action should be
1087   // commit.
1088   if (settings_.commit_to_active_tree)
1089     DCHECK(ShouldCommit());
1090 }
1091
1092 void SchedulerStateMachine::BeginMainFrameAborted(CommitEarlyOutReason reason) {
1093   DCHECK_EQ(commit_state_, COMMIT_STATE_BEGIN_MAIN_FRAME_SENT);
1094   switch (reason) {
1095     case CommitEarlyOutReason::ABORTED_OUTPUT_SURFACE_LOST:
1096     case CommitEarlyOutReason::ABORTED_NOT_VISIBLE:
1097     case CommitEarlyOutReason::ABORTED_DEFERRED_COMMIT:
1098       commit_state_ = COMMIT_STATE_IDLE;
1099       SetNeedsCommit();
1100       return;
1101     case CommitEarlyOutReason::FINISHED_NO_UPDATES:
1102       bool commit_has_no_updates = true;
1103       UpdateStateOnCommit(commit_has_no_updates);
1104       return;
1105   }
1106 }
1107
1108 void SchedulerStateMachine::DidPrepareTiles() {
1109   needs_prepare_tiles_ = false;
1110   // "Fill" the PrepareTiles funnel.
1111   prepare_tiles_funnel_++;
1112 }
1113
1114 void SchedulerStateMachine::DidLoseOutputSurface() {
1115   if (output_surface_state_ == OUTPUT_SURFACE_LOST ||
1116       output_surface_state_ == OUTPUT_SURFACE_CREATING)
1117     return;
1118   output_surface_state_ = OUTPUT_SURFACE_LOST;
1119   needs_redraw_ = false;
1120   wait_for_active_tree_ready_to_draw_ = false;
1121 }
1122
1123 void SchedulerStateMachine::NotifyReadyToActivate() {
1124   if (has_pending_tree_)
1125     pending_tree_is_ready_for_activation_ = true;
1126 }
1127
1128 void SchedulerStateMachine::NotifyReadyToDraw() {
1129   wait_for_active_tree_ready_to_draw_ = false;
1130 }
1131
1132 void SchedulerStateMachine::DidCreateAndInitializeOutputSurface() {
1133   DCHECK_EQ(output_surface_state_, OUTPUT_SURFACE_CREATING);
1134   output_surface_state_ = OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT;
1135
1136   if (did_create_and_initialize_first_output_surface_) {
1137     // TODO(boliu): See if we can remove this when impl-side painting is always
1138     // on. Does anything on the main thread need to update after recreate?
1139     needs_commit_ = true;
1140   }
1141   did_create_and_initialize_first_output_surface_ = true;
1142   pending_swaps_ = 0;
1143   swaps_with_current_output_surface_ = 0;
1144 }
1145
1146 void SchedulerStateMachine::NotifyBeginMainFrameStarted() {
1147   DCHECK_EQ(commit_state_, COMMIT_STATE_BEGIN_MAIN_FRAME_SENT);
1148   commit_state_ = COMMIT_STATE_BEGIN_MAIN_FRAME_STARTED;
1149 }
1150
1151 bool SchedulerStateMachine::HasInitializedOutputSurface() const {
1152   switch (output_surface_state_) {
1153     case OUTPUT_SURFACE_LOST:
1154     case OUTPUT_SURFACE_CREATING:
1155       return false;
1156
1157     case OUTPUT_SURFACE_ACTIVE:
1158     case OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT:
1159     case OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION:
1160       return true;
1161   }
1162   NOTREACHED();
1163   return false;
1164 }
1165
1166 }  // namespace cc