// Copyright 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "cc/scheduler/scheduler_state_machine.h"
#include "base/debug/trace_event.h"
#include "base/format_macros.h"
#include "base/logging.h"
#include "base/strings/stringprintf.h"
#include "base/values.h"
#include "ui/gfx/frame_time.h"
namespace cc {
SchedulerStateMachine::SchedulerStateMachine(const SchedulerSettings& settings)
: settings_(settings),
output_surface_state_(OUTPUT_SURFACE_LOST),
begin_impl_frame_state_(BEGIN_IMPL_FRAME_STATE_IDLE),
commit_state_(COMMIT_STATE_IDLE),
texture_state_(LAYER_TEXTURE_STATE_UNLOCKED),
forced_redraw_state_(FORCED_REDRAW_STATE_IDLE),
readback_state_(READBACK_STATE_IDLE),
commit_count_(0),
current_frame_number_(0),
last_frame_number_swap_performed_(-1),
last_frame_number_begin_main_frame_sent_(-1),
last_frame_number_update_visible_tiles_was_called_(-1),
last_frame_number_manage_tiles_called_(-1),
consecutive_failed_draws_(0),
needs_redraw_(false),
needs_manage_tiles_(false),
swap_used_incomplete_tile_(false),
needs_commit_(false),
main_thread_needs_layer_textures_(false),
inside_poll_for_anticipated_draw_triggers_(false),
visible_(false),
can_start_(false),
can_draw_(false),
has_pending_tree_(false),
pending_tree_is_ready_for_activation_(false),
active_tree_needs_first_draw_(false),
draw_if_possible_failed_(false),
did_create_and_initialize_first_output_surface_(false),
smoothness_takes_priority_(false),
skip_begin_main_frame_to_reduce_latency_(false) {}
const char* SchedulerStateMachine::OutputSurfaceStateToString(
OutputSurfaceState state) {
switch (state) {
case OUTPUT_SURFACE_ACTIVE:
return "OUTPUT_SURFACE_ACTIVE";
case OUTPUT_SURFACE_LOST:
return "OUTPUT_SURFACE_LOST";
case OUTPUT_SURFACE_CREATING:
return "OUTPUT_SURFACE_CREATING";
case OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT:
return "OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT";
case OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION:
return "OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION";
}
NOTREACHED();
return "???";
}
const char* SchedulerStateMachine::BeginImplFrameStateToString(
BeginImplFrameState state) {
switch (state) {
case BEGIN_IMPL_FRAME_STATE_IDLE:
return "BEGIN_IMPL_FRAME_STATE_IDLE";
case BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING:
return "BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING";
case BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME:
return "BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME";
case BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE:
return "BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE";
}
NOTREACHED();
return "???";
}
const char* SchedulerStateMachine::CommitStateToString(CommitState state) {
switch (state) {
case COMMIT_STATE_IDLE:
return "COMMIT_STATE_IDLE";
case COMMIT_STATE_FRAME_IN_PROGRESS:
return "COMMIT_STATE_FRAME_IN_PROGRESS";
case COMMIT_STATE_READY_TO_COMMIT:
return "COMMIT_STATE_READY_TO_COMMIT";
case COMMIT_STATE_WAITING_FOR_FIRST_DRAW:
return "COMMIT_STATE_WAITING_FOR_FIRST_DRAW";
}
NOTREACHED();
return "???";
}
const char* SchedulerStateMachine::TextureStateToString(TextureState state) {
switch (state) {
case LAYER_TEXTURE_STATE_UNLOCKED:
return "LAYER_TEXTURE_STATE_UNLOCKED";
case LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD:
return "LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD";
case LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD:
return "LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD";
}
NOTREACHED();
return "???";
}
const char* SchedulerStateMachine::SynchronousReadbackStateToString(
SynchronousReadbackState state) {
switch (state) {
case READBACK_STATE_IDLE:
return "READBACK_STATE_IDLE";
case READBACK_STATE_NEEDS_BEGIN_MAIN_FRAME:
return "READBACK_STATE_NEEDS_BEGIN_MAIN_FRAME";
case READBACK_STATE_WAITING_FOR_COMMIT:
return "READBACK_STATE_WAITING_FOR_COMMIT";
case READBACK_STATE_WAITING_FOR_ACTIVATION:
return "READBACK_STATE_WAITING_FOR_ACTIVATION";
case READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK:
return "READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK";
case READBACK_STATE_WAITING_FOR_REPLACEMENT_COMMIT:
return "READBACK_STATE_WAITING_FOR_REPLACEMENT_COMMIT";
case READBACK_STATE_WAITING_FOR_REPLACEMENT_ACTIVATION:
return "READBACK_STATE_WAITING_FOR_REPLACEMENT_ACTIVATION";
}
NOTREACHED();
return "???";
}
const char* SchedulerStateMachine::ForcedRedrawOnTimeoutStateToString(
ForcedRedrawOnTimeoutState state) {
switch (state) {
case FORCED_REDRAW_STATE_IDLE:
return "FORCED_REDRAW_STATE_IDLE";
case FORCED_REDRAW_STATE_WAITING_FOR_COMMIT:
return "FORCED_REDRAW_STATE_WAITING_FOR_COMMIT";
case FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION:
return "FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION";
case FORCED_REDRAW_STATE_WAITING_FOR_DRAW:
return "FORCED_REDRAW_STATE_WAITING_FOR_DRAW";
}
NOTREACHED();
return "???";
}
const char* SchedulerStateMachine::ActionToString(Action action) {
switch (action) {
case ACTION_NONE:
return "ACTION_NONE";
case ACTION_SEND_BEGIN_MAIN_FRAME:
return "ACTION_SEND_BEGIN_MAIN_FRAME";
case ACTION_COMMIT:
return "ACTION_COMMIT";
case ACTION_UPDATE_VISIBLE_TILES:
return "ACTION_UPDATE_VISIBLE_TILES";
case ACTION_ACTIVATE_PENDING_TREE:
return "ACTION_ACTIVATE_PENDING_TREE";
case ACTION_DRAW_AND_SWAP_IF_POSSIBLE:
return "ACTION_DRAW_AND_SWAP_IF_POSSIBLE";
case ACTION_DRAW_AND_SWAP_FORCED:
return "ACTION_DRAW_AND_SWAP_FORCED";
case ACTION_DRAW_AND_SWAP_ABORT:
return "ACTION_DRAW_AND_SWAP_ABORT";
case ACTION_DRAW_AND_READBACK:
return "ACTION_DRAW_AND_READBACK";
case ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
return "ACTION_BEGIN_OUTPUT_SURFACE_CREATION";
case ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD:
return "ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD";
case ACTION_MANAGE_TILES:
return "ACTION_MANAGE_TILES";
}
NOTREACHED();
return "???";
}
scoped_ptr<base::Value> SchedulerStateMachine::AsValue() const {
scoped_ptr<base::DictionaryValue> state(new base::DictionaryValue);
scoped_ptr<base::DictionaryValue> major_state(new base::DictionaryValue);
major_state->SetString("next_action", ActionToString(NextAction()));
major_state->SetString("begin_impl_frame_state",
BeginImplFrameStateToString(begin_impl_frame_state_));
major_state->SetString("commit_state", CommitStateToString(commit_state_));
major_state->SetString("texture_state_",
TextureStateToString(texture_state_));
major_state->SetString("output_surface_state_",
OutputSurfaceStateToString(output_surface_state_));
major_state->SetString(
"forced_redraw_state",
ForcedRedrawOnTimeoutStateToString(forced_redraw_state_));
major_state->SetString("readback_state",
SynchronousReadbackStateToString(readback_state_));
state->Set("major_state", major_state.release());
scoped_ptr<base::DictionaryValue> timestamps_state(new base::DictionaryValue);
base::TimeTicks now = gfx::FrameTime::Now();
timestamps_state->SetDouble(
"0_interval",
last_begin_impl_frame_args_.interval.InMicroseconds() / 1000.0L);
timestamps_state->SetDouble(
"1_now_to_deadline",
(last_begin_impl_frame_args_.deadline - now).InMicroseconds() / 1000.0L);
timestamps_state->SetDouble(
"2_frame_time_to_now",
(now - last_begin_impl_frame_args_.frame_time).InMicroseconds() /
1000.0L);
timestamps_state->SetDouble(
"3_frame_time_to_deadline",
(last_begin_impl_frame_args_.deadline -
last_begin_impl_frame_args_.frame_time).InMicroseconds() /
1000.0L);
timestamps_state->SetDouble(
"4_now", (now - base::TimeTicks()).InMicroseconds() / 1000.0L);
timestamps_state->SetDouble(
"5_frame_time",
(last_begin_impl_frame_args_.frame_time - base::TimeTicks())
.InMicroseconds() /
1000.0L);
timestamps_state->SetDouble(
"6_deadline",
(last_begin_impl_frame_args_.deadline - base::TimeTicks())
.InMicroseconds() /
1000.0L);
state->Set("major_timestamps_in_ms", timestamps_state.release());
scoped_ptr<base::DictionaryValue> minor_state(new base::DictionaryValue);
minor_state->SetInteger("commit_count", commit_count_);
minor_state->SetInteger("current_frame_number", current_frame_number_);
minor_state->SetInteger("last_frame_number_swap_performed",
last_frame_number_swap_performed_);
minor_state->SetInteger(
"last_frame_number_begin_main_frame_sent",
last_frame_number_begin_main_frame_sent_);
minor_state->SetInteger(
"last_frame_number_update_visible_tiles_was_called",
last_frame_number_update_visible_tiles_was_called_);
minor_state->SetInteger("consecutive_failed_draws",
consecutive_failed_draws_);
minor_state->SetBoolean("needs_redraw", needs_redraw_);
minor_state->SetBoolean("needs_manage_tiles", needs_manage_tiles_);
minor_state->SetBoolean("swap_used_incomplete_tile",
swap_used_incomplete_tile_);
minor_state->SetBoolean("needs_commit", needs_commit_);
minor_state->SetBoolean("main_thread_needs_layer_textures",
main_thread_needs_layer_textures_);
minor_state->SetBoolean("visible", visible_);
minor_state->SetBoolean("can_start", can_start_);
minor_state->SetBoolean("can_draw", can_draw_);
minor_state->SetBoolean("has_pending_tree", has_pending_tree_);
minor_state->SetBoolean("pending_tree_is_ready_for_activation",
pending_tree_is_ready_for_activation_);
minor_state->SetBoolean("active_tree_needs_first_draw",
active_tree_needs_first_draw_);
minor_state->SetBoolean("draw_if_possible_failed", draw_if_possible_failed_);
minor_state->SetBoolean("did_create_and_initialize_first_output_surface",
did_create_and_initialize_first_output_surface_);
minor_state->SetBoolean("smoothness_takes_priority",
smoothness_takes_priority_);
minor_state->SetBoolean("main_thread_is_in_high_latency_mode",
MainThreadIsInHighLatencyMode());
minor_state->SetBoolean("skip_begin_main_frame_to_reduce_latency",
skip_begin_main_frame_to_reduce_latency_);
state->Set("minor_state", minor_state.release());
return state.PassAs<base::Value>();
}
bool SchedulerStateMachine::HasSentBeginMainFrameThisFrame() const {
return current_frame_number_ ==
last_frame_number_begin_main_frame_sent_;
}
bool SchedulerStateMachine::HasUpdatedVisibleTilesThisFrame() const {
return current_frame_number_ ==
last_frame_number_update_visible_tiles_was_called_;
}
bool SchedulerStateMachine::HasSwappedThisFrame() const {
return current_frame_number_ == last_frame_number_swap_performed_;
}
bool SchedulerStateMachine::PendingDrawsShouldBeAborted() const {
// These are all the cases where we normally cannot or do not want to draw
// but, if needs_redraw_ is true and we do not draw to make forward progress,
// we might deadlock with the main thread.
// This should be a superset of PendingActivationsShouldBeForced() since
// activation of the pending tree is blocked by drawing of the active tree and
// the main thread might be blocked on activation of the most recent commit.
if (PendingActivationsShouldBeForced())
return true;
// Additional states where we should abort draws.
// Note: We don't force activation in these cases because doing so would
// result in checkerboarding on resize, becoming visible, etc.
if (!can_draw_)
return true;
if (!visible_)
return true;
return false;
}
bool SchedulerStateMachine::PendingActivationsShouldBeForced() const {
// These are all the cases where, if we do not force activations to make
// forward progress, we might deadlock with the main thread.
// The impl thread cannot lock layer textures unless the pending
// tree can be activated to unblock the commit.
if (texture_state_ == LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD)
return true;
// There is no output surface to trigger our activations.
if (output_surface_state_ == OUTPUT_SURFACE_LOST)
return true;
return false;
}
bool SchedulerStateMachine::ShouldBeginOutputSurfaceCreation() const {
// Don't try to initialize too early.
if (!can_start_)
return false;
// We only want to start output surface initialization after the
// previous commit is complete.
if (commit_state_ != COMMIT_STATE_IDLE)
return false;
// We want to clear the pipline of any pending draws and activations
// before starting output surface initialization. This allows us to avoid
// weird corner cases where we abort draws or force activation while we
// are initializing the output surface and can potentially have a pending
// readback.
if (active_tree_needs_first_draw_ || has_pending_tree_)
return false;
// We need to create the output surface if we don't have one and we haven't
// started creating one yet.
return output_surface_state_ == OUTPUT_SURFACE_LOST;
}
bool SchedulerStateMachine::ShouldDraw() const {
// After a readback, make sure not to draw again until we've replaced the
// readback commit with a real one.
if (readback_state_ == READBACK_STATE_WAITING_FOR_REPLACEMENT_COMMIT ||
readback_state_ == READBACK_STATE_WAITING_FOR_REPLACEMENT_ACTIVATION)
return false;
// Draw immediately for readbacks to unblock the main thread quickly.
if (readback_state_ == READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK) {
DCHECK_EQ(commit_state_, COMMIT_STATE_WAITING_FOR_FIRST_DRAW);
return true;
}
// If we need to abort draws, we should do so ASAP since the draw could
// be blocking other important actions (like output surface initialization),
// from occuring. If we are waiting for the first draw, then perfom the
// aborted draw to keep things moving. If we are not waiting for the first
// draw however, we don't want to abort for no reason.
if (PendingDrawsShouldBeAborted())
return active_tree_needs_first_draw_;
// After this line, we only want to swap once per frame.
if (HasSwappedThisFrame())
return false;
// Except for the cases above, do not draw outside of the BeginImplFrame
// deadline.
if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
return false;
// Only handle forced redraws due to timeouts on the regular deadline.
if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW) {
DCHECK_EQ(commit_state_, COMMIT_STATE_WAITING_FOR_FIRST_DRAW);
return true;
}
return needs_redraw_;
}
bool SchedulerStateMachine::ShouldAcquireLayerTexturesForMainThread() const {
if (!main_thread_needs_layer_textures_)
return false;
if (texture_state_ == LAYER_TEXTURE_STATE_UNLOCKED)
return true;
DCHECK_EQ(texture_state_, LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD);
return false;
}
bool SchedulerStateMachine::ShouldActivatePendingTree() const {
// There is nothing to activate.
if (!has_pending_tree_)
return false;
// We should not activate a second tree before drawing the first one.
// Even if we need to force activation of the pending tree, we should abort
// drawing the active tree first.
if (active_tree_needs_first_draw_)
return false;
// If we want to force activation, do so ASAP.
if (PendingActivationsShouldBeForced())
return true;
// At this point, only activate if we are ready to activate.
return pending_tree_is_ready_for_activation_;
}
bool SchedulerStateMachine::ShouldUpdateVisibleTiles() const {
if (!settings_.impl_side_painting)
return false;
if (HasUpdatedVisibleTilesThisFrame())
return false;
// There's no reason to check for tiles if we don't have an output surface.
if (!HasInitializedOutputSurface())
return false;
// We should not check for visible tiles until we've entered the deadline so
// we check as late as possible and give the tiles more time to initialize.
if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
return false;
// If the last swap drew with checkerboard or missing tiles, we should
// poll for any new visible tiles so we can be notified to draw again
// when there are.
if (swap_used_incomplete_tile_)
return true;
return false;
}
bool SchedulerStateMachine::ShouldSendBeginMainFrame() const {
if (!needs_commit_)
return false;
// Only send BeginMainFrame when there isn't another commit pending already.
if (commit_state_ != COMMIT_STATE_IDLE)
return false;
// We can't accept a commit if we have a pending tree.
if (has_pending_tree_)
return false;
// We want to handle readback commits immediately to unblock the main thread.
// Note: This BeginMainFrame will correspond to the replacement commit that
// comes after the readback commit itself, so we only send the BeginMainFrame
// if a commit isn't already pending behind the readback.
if (readback_state_ == READBACK_STATE_NEEDS_BEGIN_MAIN_FRAME)
return !CommitPending();
// We do not need commits if we are not visible, unless there's a
// request for a readback.
if (!visible_)
return false;
// We want to start the first commit after we get a new output surface ASAP.
if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT)
return true;
// With deadline scheduling enabled, we should not send BeginMainFrame while
// we are in BEGIN_IMPL_FRAME_STATE_IDLE, since we might have new user input
// coming in soon.
// However, if we are not expecting a BeginImplFrame to take us out of idle,
// we should not early out here to avoid blocking commits forever.
// This only works well when deadline scheduling is enabled because there is
// an interval over which to accept the commit and draw. Without deadline
// scheduling, delaying the commit could prevent us from having something
// to draw on the next BeginImplFrame.
// TODO(brianderson): Allow sending BeginMainFrame while idle when the main
// thread isn't consuming user input.
if (settings_.deadline_scheduling_enabled &&
begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_IDLE &&
BeginImplFrameNeeded())
return false;
// We need a new commit for the forced redraw. This honors the
// single commit per interval because the result will be swapped to screen.
if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT)
return true;
// After this point, we only start a commit once per frame.
if (HasSentBeginMainFrameThisFrame())
return false;
// We shouldn't normally accept commits if there isn't an OutputSurface.
if (!HasInitializedOutputSurface())
return false;
if (skip_begin_main_frame_to_reduce_latency_)
return false;
return true;
}
bool SchedulerStateMachine::ShouldCommit() const {
return commit_state_ == COMMIT_STATE_READY_TO_COMMIT;
}
bool SchedulerStateMachine::IsCommitStateWaiting() const {
return commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS;
}
bool SchedulerStateMachine::ShouldManageTiles() const {
// ManageTiles only really needs to be called immediately after commit
// and then periodically after that. Limiting to once per frame prevents
// post-commit and post-draw ManageTiles on the same frame.
if (last_frame_number_manage_tiles_called_ == current_frame_number_)
return false;
// Limiting to once per-frame is not enough, since we only want to
// manage tiles _after_ draws. Polling for draw triggers and
// begin-frame are mutually exclusive, so we limit to these two cases.
if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE &&
!inside_poll_for_anticipated_draw_triggers_)
return false;
return needs_manage_tiles_;
}
SchedulerStateMachine::Action SchedulerStateMachine::NextAction() const {
if (ShouldAcquireLayerTexturesForMainThread())
return ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD;
if (ShouldUpdateVisibleTiles())
return ACTION_UPDATE_VISIBLE_TILES;
if (ShouldActivatePendingTree())
return ACTION_ACTIVATE_PENDING_TREE;
if (ShouldCommit())
return ACTION_COMMIT;
if (ShouldDraw()) {
if (readback_state_ == READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK)
return ACTION_DRAW_AND_READBACK;
else if (PendingDrawsShouldBeAborted())
return ACTION_DRAW_AND_SWAP_ABORT;
else if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
return ACTION_DRAW_AND_SWAP_FORCED;
else
return ACTION_DRAW_AND_SWAP_IF_POSSIBLE;
}
if (ShouldManageTiles())
return ACTION_MANAGE_TILES;
if (ShouldSendBeginMainFrame())
return ACTION_SEND_BEGIN_MAIN_FRAME;
if (ShouldBeginOutputSurfaceCreation())
return ACTION_BEGIN_OUTPUT_SURFACE_CREATION;
return ACTION_NONE;
}
void SchedulerStateMachine::CheckInvariants() {
// We should never try to perform a draw for readback and forced draw due to
// timeout simultaneously.
DCHECK(!(forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW &&
readback_state_ == READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK));
}
void SchedulerStateMachine::UpdateState(Action action) {
switch (action) {
case ACTION_NONE:
return;
case ACTION_UPDATE_VISIBLE_TILES:
last_frame_number_update_visible_tiles_was_called_ =
current_frame_number_;
return;
case ACTION_ACTIVATE_PENDING_TREE:
UpdateStateOnActivation();
return;
case ACTION_SEND_BEGIN_MAIN_FRAME:
DCHECK(!has_pending_tree_);
DCHECK(visible_ ||
readback_state_ == READBACK_STATE_NEEDS_BEGIN_MAIN_FRAME);
commit_state_ = COMMIT_STATE_FRAME_IN_PROGRESS;
needs_commit_ = false;
if (readback_state_ == READBACK_STATE_NEEDS_BEGIN_MAIN_FRAME)
readback_state_ = READBACK_STATE_WAITING_FOR_COMMIT;
last_frame_number_begin_main_frame_sent_ =
current_frame_number_;
return;
case ACTION_COMMIT: {
bool commit_was_aborted = false;
UpdateStateOnCommit(commit_was_aborted);
return;
}
case ACTION_DRAW_AND_SWAP_FORCED:
case ACTION_DRAW_AND_SWAP_IF_POSSIBLE: {
bool did_swap = true;
UpdateStateOnDraw(did_swap);
return;
}
case ACTION_DRAW_AND_SWAP_ABORT:
case ACTION_DRAW_AND_READBACK: {
bool did_swap = false;
UpdateStateOnDraw(did_swap);
return;
}
case ACTION_BEGIN_OUTPUT_SURFACE_CREATION:
DCHECK_EQ(output_surface_state_, OUTPUT_SURFACE_LOST);
output_surface_state_ = OUTPUT_SURFACE_CREATING;
// The following DCHECKs make sure we are in the proper quiescent state.
// The pipeline should be flushed entirely before we start output
// surface creation to avoid complicated corner cases.
DCHECK_EQ(commit_state_, COMMIT_STATE_IDLE);
DCHECK(!has_pending_tree_);
DCHECK(!active_tree_needs_first_draw_);
return;
case ACTION_ACQUIRE_LAYER_TEXTURES_FOR_MAIN_THREAD:
texture_state_ = LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD;
main_thread_needs_layer_textures_ = false;
return;
case ACTION_MANAGE_TILES:
UpdateStateOnManageTiles();
return;
}
}
void SchedulerStateMachine::UpdateStateOnCommit(bool commit_was_aborted) {
commit_count_++;
// If we are impl-side-painting but the commit was aborted, then we behave
// mostly as if we are not impl-side-painting since there is no pending tree.
has_pending_tree_ = settings_.impl_side_painting && !commit_was_aborted;
// Update state related to readbacks.
if (readback_state_ == READBACK_STATE_WAITING_FOR_COMMIT) {
// Update the state if this is the readback commit.
readback_state_ = has_pending_tree_
? READBACK_STATE_WAITING_FOR_ACTIVATION
: READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK;
} else if (readback_state_ == READBACK_STATE_WAITING_FOR_REPLACEMENT_COMMIT) {
// Update the state if this is the commit replacing the readback commit.
readback_state_ = has_pending_tree_
? READBACK_STATE_WAITING_FOR_REPLACEMENT_ACTIVATION
: READBACK_STATE_IDLE;
} else {
DCHECK(readback_state_ == READBACK_STATE_IDLE);
}
// Readbacks can interrupt output surface initialization and forced draws,
// so we do not want to advance those states if we are in the middle of a
// readback. Note: It is possible for the readback's replacement commit to
// be the output surface's first commit and/or the forced redraw's commit.
if (readback_state_ == READBACK_STATE_IDLE ||
readback_state_ == READBACK_STATE_WAITING_FOR_REPLACEMENT_ACTIVATION) {
// Update state related to forced draws.
if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_COMMIT) {
forced_redraw_state_ = has_pending_tree_
? FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION
: FORCED_REDRAW_STATE_WAITING_FOR_DRAW;
}
// Update the output surface state.
DCHECK_NE(output_surface_state_,
OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION);
if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT) {
if (has_pending_tree_) {
output_surface_state_ = OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION;
} else {
output_surface_state_ = OUTPUT_SURFACE_ACTIVE;
needs_redraw_ = true;
}
}
}
// Update the commit state. We expect and wait for a draw if the commit
// was not aborted or if we are in a readback or forced draw.
if (!commit_was_aborted) {
DCHECK(commit_state_ == COMMIT_STATE_READY_TO_COMMIT);
commit_state_ = COMMIT_STATE_WAITING_FOR_FIRST_DRAW;
} else if (readback_state_ != READBACK_STATE_IDLE ||
forced_redraw_state_ != FORCED_REDRAW_STATE_IDLE) {
commit_state_ = COMMIT_STATE_WAITING_FOR_FIRST_DRAW;
} else {
commit_state_ = COMMIT_STATE_IDLE;
}
// Update state if we have a new active tree to draw, or if the active tree
// was unchanged but we need to do a readback or forced draw.
if (!has_pending_tree_ &&
(!commit_was_aborted ||
readback_state_ == READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK ||
forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)) {
needs_redraw_ = true;
active_tree_needs_first_draw_ = true;
}
// This post-commit work is common to both completed and aborted commits.
pending_tree_is_ready_for_activation_ = false;
if (draw_if_possible_failed_)
last_frame_number_swap_performed_ = -1;
// If we are planing to draw with the new commit, lock the layer textures for
// use on the impl thread. Otherwise, leave them unlocked.
if (has_pending_tree_ || needs_redraw_)
texture_state_ = LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD;
else
texture_state_ = LAYER_TEXTURE_STATE_UNLOCKED;
}
void SchedulerStateMachine::UpdateStateOnActivation() {
// Update output surface state.
if (output_surface_state_ == OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION)
output_surface_state_ = OUTPUT_SURFACE_ACTIVE;
// Update readback state
if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_ACTIVATION)
forced_redraw_state_ = FORCED_REDRAW_STATE_WAITING_FOR_DRAW;
// Update forced redraw state
if (readback_state_ == READBACK_STATE_WAITING_FOR_ACTIVATION)
readback_state_ = READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK;
else if (readback_state_ == READBACK_STATE_WAITING_FOR_REPLACEMENT_ACTIVATION)
readback_state_ = READBACK_STATE_IDLE;
has_pending_tree_ = false;
pending_tree_is_ready_for_activation_ = false;
active_tree_needs_first_draw_ = true;
needs_redraw_ = true;
}
void SchedulerStateMachine::UpdateStateOnDraw(bool did_swap) {
DCHECK(readback_state_ != READBACK_STATE_WAITING_FOR_REPLACEMENT_COMMIT &&
readback_state_ != READBACK_STATE_WAITING_FOR_REPLACEMENT_ACTIVATION)
<< *AsValue();
if (readback_state_ == READBACK_STATE_WAITING_FOR_DRAW_AND_READBACK) {
// The draw correspons to a readback commit.
DCHECK_EQ(commit_state_, COMMIT_STATE_WAITING_FOR_FIRST_DRAW);
// We are blocking commits from the main thread until after this draw, so
// we should not have a pending tree.
DCHECK(!has_pending_tree_);
// We transition to COMMIT_STATE_FRAME_IN_PROGRESS because there is a
// pending BeginMainFrame behind the readback request.
commit_state_ = COMMIT_STATE_FRAME_IN_PROGRESS;
readback_state_ = READBACK_STATE_WAITING_FOR_REPLACEMENT_COMMIT;
} else if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW) {
DCHECK_EQ(commit_state_, COMMIT_STATE_WAITING_FOR_FIRST_DRAW);
commit_state_ = COMMIT_STATE_IDLE;
forced_redraw_state_ = FORCED_REDRAW_STATE_IDLE;
} else if (commit_state_ == COMMIT_STATE_WAITING_FOR_FIRST_DRAW &&
!has_pending_tree_) {
commit_state_ = COMMIT_STATE_IDLE;
}
if (texture_state_ == LAYER_TEXTURE_STATE_ACQUIRED_BY_IMPL_THREAD)
texture_state_ = LAYER_TEXTURE_STATE_UNLOCKED;
needs_redraw_ = false;
draw_if_possible_failed_ = false;
active_tree_needs_first_draw_ = false;
if (did_swap)
last_frame_number_swap_performed_ = current_frame_number_;
}
void SchedulerStateMachine::UpdateStateOnManageTiles() {
needs_manage_tiles_ = false;
}
void SchedulerStateMachine::SetMainThreadNeedsLayerTextures() {
DCHECK(!main_thread_needs_layer_textures_);
DCHECK_NE(texture_state_, LAYER_TEXTURE_STATE_ACQUIRED_BY_MAIN_THREAD);
main_thread_needs_layer_textures_ = true;
}
void SchedulerStateMachine::SetSkipBeginMainFrameToReduceLatency(bool skip) {
skip_begin_main_frame_to_reduce_latency_ = skip;
}
bool SchedulerStateMachine::BeginImplFrameNeeded() const {
// Proactive BeginImplFrames are bad for the synchronous compositor because we
// have to draw when we get the BeginImplFrame and could end up drawing many
// duplicate frames if our new frame isn't ready in time.
// To poll for state with the synchronous compositor without having to draw,
// we rely on ShouldPollForAnticipatedDrawTriggers instead.
if (!SupportsProactiveBeginImplFrame())
return BeginImplFrameNeededToDraw();
return BeginImplFrameNeededToDraw() ||
ProactiveBeginImplFrameWanted();
}
bool SchedulerStateMachine::ShouldPollForAnticipatedDrawTriggers() const {
// ShouldPollForAnticipatedDrawTriggers is what we use in place of
// ProactiveBeginImplFrameWanted when we are using the synchronous
// compositor.
if (!SupportsProactiveBeginImplFrame()) {
return !BeginImplFrameNeededToDraw() &&
ProactiveBeginImplFrameWanted();
}
// Non synchronous compositors should rely on
// ProactiveBeginImplFrameWanted to poll for state instead.
return false;
}
bool SchedulerStateMachine::SupportsProactiveBeginImplFrame() const {
// Both the synchronous compositor and disabled vsync settings
// make it undesirable to proactively request BeginImplFrames.
// If this is true, the scheduler should poll.
return !settings_.using_synchronous_renderer_compositor &&
settings_.throttle_frame_production;
}
// These are the cases where we definitely (or almost definitely) have a
// new frame to draw and can draw.
bool SchedulerStateMachine::BeginImplFrameNeededToDraw() const {
// The output surface is the provider of BeginImplFrames, so we are not going
// to get them even if we ask for them.
if (!HasInitializedOutputSurface())
return false;
// If we can't draw, don't tick until we are notified that we can draw again.
if (!can_draw_)
return false;
// The forced draw respects our normal draw scheduling, so we need to
// request a BeginImplFrame for it.
if (forced_redraw_state_ == FORCED_REDRAW_STATE_WAITING_FOR_DRAW)
return true;
// There's no need to produce frames if we are not visible.
if (!visible_)
return false;
// We need to draw a more complete frame than we did the last BeginImplFrame,
// so request another BeginImplFrame in anticipation that we will have
// additional visible tiles.
if (swap_used_incomplete_tile_)
return true;
return needs_redraw_;
}
// These are cases where we are very likely to draw soon, but might not
// actually have a new frame to draw when we receive the next BeginImplFrame.
// Proactively requesting the BeginImplFrame helps hide the round trip latency
// of the SetNeedsBeginImplFrame request that has to go to the Browser.
bool SchedulerStateMachine::ProactiveBeginImplFrameWanted() const {
// The output surface is the provider of BeginImplFrames,
// so we are not going to get them even if we ask for them.
if (!HasInitializedOutputSurface())
return false;
// Do not be proactive when invisible.
if (!visible_)
return false;
// We should proactively request a BeginImplFrame if a commit is pending
// because we will want to draw if the commit completes quickly.
if (needs_commit_ || commit_state_ != COMMIT_STATE_IDLE)
return true;
// If the pending tree activates quickly, we'll want a BeginImplFrame soon
// to draw the new active tree.
if (has_pending_tree_)
return true;
// Changing priorities may allow us to activate (given the new priorities),
// which may result in a new frame.
if (needs_manage_tiles_)
return true;
// If we just swapped, it's likely that we are going to produce another
// frame soon. This helps avoid negative glitches in our
// SetNeedsBeginImplFrame requests, which may propagate to the BeginImplFrame
// provider and get sampled at an inopportune time, delaying the next
// BeginImplFrame.
if (last_frame_number_swap_performed_ == current_frame_number_)
return true;
return false;
}
void SchedulerStateMachine::OnBeginImplFrame(const BeginFrameArgs& args) {
current_frame_number_++;
last_begin_impl_frame_args_ = args;
DCHECK_EQ(begin_impl_frame_state_, BEGIN_IMPL_FRAME_STATE_IDLE) << *AsValue();
begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING;
}
void SchedulerStateMachine::OnBeginImplFrameDeadlinePending() {
DCHECK_EQ(begin_impl_frame_state_,
BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING)
<< *AsValue();
begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME;
}
void SchedulerStateMachine::OnBeginImplFrameDeadline() {
DCHECK_EQ(begin_impl_frame_state_, BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME)
<< *AsValue();
begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE;
}
void SchedulerStateMachine::OnBeginImplFrameIdle() {
DCHECK_EQ(begin_impl_frame_state_, BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE)
<< *AsValue();
begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_IDLE;
}
bool SchedulerStateMachine::ShouldTriggerBeginImplFrameDeadlineEarly() const {
// TODO(brianderson): This should take into account multiple commit sources.
// If we are in the middle of the readback, we won't swap, so there is
// no reason to trigger the deadline early.
if (readback_state_ != READBACK_STATE_IDLE)
return false;
if (begin_impl_frame_state_ != BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME)
return false;
if (active_tree_needs_first_draw_)
return true;
if (!needs_redraw_)
return false;
// This is used to prioritize impl-thread draws when the main thread isn't
// producing anything, e.g., after an aborted commit. We also check that we
// don't have a pending tree -- otherwise we should give it a chance to
// activate.
// TODO(skyostil): Revisit this when we have more accurate deadline estimates.
if (commit_state_ == COMMIT_STATE_IDLE && !has_pending_tree_)
return true;
// Prioritize impl-thread draws in smoothness mode.
if (smoothness_takes_priority_)
return true;
return false;
}
bool SchedulerStateMachine::MainThreadIsInHighLatencyMode() const {
// If we just sent a BeginMainFrame and haven't hit the deadline yet, the main
// thread is in a low latency mode.
if (last_frame_number_begin_main_frame_sent_ == current_frame_number_ &&
(begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_BEGIN_FRAME_STARTING ||
begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_INSIDE_BEGIN_FRAME))
return false;
// If there's a commit in progress it must either be from the previous frame
// or it started after the impl thread's deadline. In either case the main
// thread is in high latency mode.
if (commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS ||
commit_state_ == COMMIT_STATE_READY_TO_COMMIT)
return true;
// Similarly, if there's a pending tree the main thread is in high latency
// mode, because either
// it's from the previous frame
// or
// we're currently drawing the active tree and the pending tree will thus
// only be drawn in the next frame.
if (has_pending_tree_)
return true;
if (begin_impl_frame_state_ == BEGIN_IMPL_FRAME_STATE_INSIDE_DEADLINE) {
// Even if there's a new active tree to draw at the deadline or we've just
// drawn it, it may have been triggered by a previous BeginImplFrame, in
// which case the main thread is in a high latency mode.
return (active_tree_needs_first_draw_ ||
last_frame_number_swap_performed_ == current_frame_number_) &&
last_frame_number_begin_main_frame_sent_ != current_frame_number_;
}
// If the active tree needs its first draw in any other state, we know the
// main thread is in a high latency mode.
return active_tree_needs_first_draw_;
}
void SchedulerStateMachine::DidEnterPollForAnticipatedDrawTriggers() {
current_frame_number_++;
inside_poll_for_anticipated_draw_triggers_ = true;
}
void SchedulerStateMachine::DidLeavePollForAnticipatedDrawTriggers() {
inside_poll_for_anticipated_draw_triggers_ = false;
}
void SchedulerStateMachine::SetVisible(bool visible) { visible_ = visible; }
void SchedulerStateMachine::SetCanDraw(bool can_draw) { can_draw_ = can_draw; }
void SchedulerStateMachine::SetNeedsRedraw() { needs_redraw_ = true; }
void SchedulerStateMachine::SetNeedsManageTiles() {
if (!needs_manage_tiles_) {
TRACE_EVENT0("cc",
"SchedulerStateMachine::SetNeedsManageTiles");
needs_manage_tiles_ = true;
}
}
void SchedulerStateMachine::SetSwapUsedIncompleteTile(
bool used_incomplete_tile) {
swap_used_incomplete_tile_ = used_incomplete_tile;
}
void SchedulerStateMachine::SetSmoothnessTakesPriority(
bool smoothness_takes_priority) {
smoothness_takes_priority_ = smoothness_takes_priority;
}
void SchedulerStateMachine::DidDrawIfPossibleCompleted(bool success) {
draw_if_possible_failed_ = !success;
if (draw_if_possible_failed_) {
needs_redraw_ = true;
// If we're already in the middle of a redraw, we don't need to
// restart it.
if (forced_redraw_state_ != FORCED_REDRAW_STATE_IDLE)
return;
needs_commit_ = true;
consecutive_failed_draws_++;
if (settings_.timeout_and_draw_when_animation_checkerboards &&
consecutive_failed_draws_ >=
settings_.maximum_number_of_failed_draws_before_draw_is_forced_) {
consecutive_failed_draws_ = 0;
// We need to force a draw, but it doesn't make sense to do this until
// we've committed and have new textures.
forced_redraw_state_ = FORCED_REDRAW_STATE_WAITING_FOR_COMMIT;
}
} else {
consecutive_failed_draws_ = 0;
forced_redraw_state_ = FORCED_REDRAW_STATE_IDLE;
}
}
void SchedulerStateMachine::SetNeedsCommit() { needs_commit_ = true; }
void SchedulerStateMachine::SetNeedsForcedCommitForReadback() {
// If this is called in READBACK_STATE_IDLE, this is a "first" readback
// request.
// If this is called in READBACK_STATE_WAITING_FOR_REPLACEMENT_COMMIT, this
// is a back-to-back readback request that started before the replacement
// commit had a chance to land.
DCHECK(readback_state_ == READBACK_STATE_IDLE ||
readback_state_ == READBACK_STATE_WAITING_FOR_REPLACEMENT_COMMIT);
// If there is already a commit in progress when we get the readback request
// (we are in COMMIT_STATE_FRAME_IN_PROGRESS), then we don't need to send a
// BeginMainFrame for the replacement commit, since there's already a
// BeginMainFrame behind the readback request. In that case, we can skip
// READBACK_STATE_NEEDS_BEGIN_MAIN_FRAME and go directly to
// READBACK_STATE_WAITING_FOR_COMMIT
if (commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS)
readback_state_ = READBACK_STATE_WAITING_FOR_COMMIT;
else
readback_state_ = READBACK_STATE_NEEDS_BEGIN_MAIN_FRAME;
}
void SchedulerStateMachine::FinishCommit() {
DCHECK(commit_state_ == COMMIT_STATE_FRAME_IN_PROGRESS) << *AsValue();
commit_state_ = COMMIT_STATE_READY_TO_COMMIT;
}
void SchedulerStateMachine::BeginMainFrameAborted(bool did_handle) {
DCHECK_EQ(commit_state_, COMMIT_STATE_FRAME_IN_PROGRESS);
if (did_handle) {
bool commit_was_aborted = true;
UpdateStateOnCommit(commit_was_aborted);
} else {
DCHECK_NE(readback_state_, READBACK_STATE_WAITING_FOR_COMMIT);
commit_state_ = COMMIT_STATE_IDLE;
SetNeedsCommit();
}
}
void SchedulerStateMachine::DidManageTiles() {
needs_manage_tiles_ = false;
last_frame_number_manage_tiles_called_ = current_frame_number_;
}
void SchedulerStateMachine::DidLoseOutputSurface() {
if (output_surface_state_ == OUTPUT_SURFACE_LOST ||
output_surface_state_ == OUTPUT_SURFACE_CREATING)
return;
output_surface_state_ = OUTPUT_SURFACE_LOST;
needs_redraw_ = false;
begin_impl_frame_state_ = BEGIN_IMPL_FRAME_STATE_IDLE;
}
void SchedulerStateMachine::NotifyReadyToActivate() {
if (has_pending_tree_)
pending_tree_is_ready_for_activation_ = true;
}
void SchedulerStateMachine::DidCreateAndInitializeOutputSurface() {
DCHECK_EQ(output_surface_state_, OUTPUT_SURFACE_CREATING);
output_surface_state_ = OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT;
if (did_create_and_initialize_first_output_surface_) {
// TODO(boliu): See if we can remove this when impl-side painting is always
// on. Does anything on the main thread need to update after recreate?
needs_commit_ = true;
}
did_create_and_initialize_first_output_surface_ = true;
}
bool SchedulerStateMachine::HasInitializedOutputSurface() const {
switch (output_surface_state_) {
case OUTPUT_SURFACE_LOST:
case OUTPUT_SURFACE_CREATING:
return false;
case OUTPUT_SURFACE_ACTIVE:
case OUTPUT_SURFACE_WAITING_FOR_FIRST_COMMIT:
case OUTPUT_SURFACE_WAITING_FOR_FIRST_ACTIVATION:
return true;
}
NOTREACHED();
return false;
}
} // namespace cc