Add DisplayScheduler for Surfaces

cc/surfaces/display_scheduler.cc

+// Copyright 2015 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/surfaces/display_scheduler.h"
+
+#include <vector>
+
+#include "base/stl_util.h"
+#include "base/trace_event/trace_event.h"
+#include "cc/output/output_surface.h"
+#include "ui/gfx/frame_time.h"
+
+namespace cc {
+
+DisplayScheduler::DisplayScheduler(
+    DisplaySchedulerClient* client,
+    BeginFrameSource* begin_frame_source,
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+    int max_pending_swaps)
+    : client_(client),
+      begin_frame_source_(begin_frame_source),
+      task_runner_(task_runner),
+      output_surface_lost_(false),
+      root_surface_resources_locked_(true),
+      inside_begin_frame_deadline_interval_(false),
+      needs_draw_(false),
+      entire_display_damaged_(false),
+      all_active_child_surfaces_ready_to_draw_(false),
+      pending_swaps_(0),
+      max_pending_swaps_(max_pending_swaps),
+      root_surface_damaged_(false),
+      expect_damage_from_root_surface_(false),
+      weak_ptr_factory_(this) {
+  begin_frame_source_->AddObserver(this);
+  begin_frame_deadline_closure_ = base::Bind(
+      &DisplayScheduler::OnBeginFrameDeadline, weak_ptr_factory_.GetWeakPtr());
+}
+
+DisplayScheduler::~DisplayScheduler() {
+  begin_frame_source_->RemoveObserver(this);
+}
+
+// If we try to draw when the root surface resources are locked, the
+// draw will fail.
+void DisplayScheduler::SetRootSurfaceResourcesLocked(bool locked) {
+  root_surface_resources_locked_ = locked;
+  ScheduleBeginFrameDeadline();
+}
+
+// Notification that there was a resize or the root surface changed and
+// that we should just draw immediately.
+void DisplayScheduler::EntireDisplayDamaged(SurfaceId root_surface_id) {
+  TRACE_EVENT0("cc", "DisplayScheduler::EntireDisplayDamaged");
+  needs_draw_ = true;
+  entire_display_damaged_ = true;
+  root_surface_id_ = root_surface_id;
+
+  begin_frame_source_->SetNeedsBeginFrames(!output_surface_lost_);
+  ScheduleBeginFrameDeadline();
+}
+
+// Indicates that there was damage to one of the surfaces.
+// Has some logic to wait for multiple active surfaces before
+// triggering the deadline.
+void DisplayScheduler::SurfaceDamaged(SurfaceId surface_id) {
+  TRACE_EVENT1("cc", "DisplayScheduler::SurfaceDamaged", "surface_id",
+               surface_id.id);
+
+  needs_draw_ = true;
+
+  if (surface_id == root_surface_id_) {
+    root_surface_damaged_ = true;
+  } else {
+    child_surface_ids_damaged_.insert(surface_id);
+
+    // TODO(mithro): Use hints from SetNeedsBeginFrames and SwapAborts.
+    all_active_child_surfaces_ready_to_draw_ = base::STLIncludes(
+        child_surface_ids_damaged_, child_surface_ids_to_expect_damage_from_);
+  }
+
+  begin_frame_source_->SetNeedsBeginFrames(!output_surface_lost_);
+  ScheduleBeginFrameDeadline();
+}
+
+void DisplayScheduler::OutputSurfaceLost() {
+  TRACE_EVENT0("cc", "DisplayScheduler::OutputSurfaceLost");
+  output_surface_lost_ = true;
+  begin_frame_source_->SetNeedsBeginFrames(false);
+  ScheduleBeginFrameDeadline();
+}
+
+void DisplayScheduler::DrawAndSwap() {
+  TRACE_EVENT0("cc", "DisplayScheduler::DrawAndSwap");
+  DCHECK_LT(pending_swaps_, max_pending_swaps_);
+  DCHECK(!output_surface_lost_);
+
+  bool success = client_->DrawAndSwap();
+  if (!success)
+    return;
+
+  needs_draw_ = false;
+  entire_display_damaged_ = false;
+  all_active_child_surfaces_ready_to_draw_ = false;
+
+  expect_damage_from_root_surface_ = root_surface_damaged_;
+  root_surface_damaged_ = false;
+
+  child_surface_ids_to_expect_damage_from_ =
+      base::STLSetIntersection<std::vector<SurfaceId>>(
+          child_surface_ids_damaged_, child_surface_ids_damaged_prev_);
+
+  child_surface_ids_damaged_prev_.swap(child_surface_ids_damaged_);
+  child_surface_ids_damaged_.clear();
+}
+
+bool DisplayScheduler::OnBeginFrameMixInDelegate(const BeginFrameArgs& args) {
+  base::TimeTicks now = gfx::FrameTime::Now();
+  TRACE_EVENT2("cc", "DisplayScheduler::BeginFrame", "args", args.AsValue(),
+               "now", now);
+
+  // Only service missed BeginFrames if they haven't already expired.
+  base::TimeTicks adjusted_deadline =
+      args.deadline - BeginFrameArgs::DefaultEstimatedParentDrawTime();
+  if (args.type == BeginFrameArgs::MISSED && now > adjusted_deadline)
+    return false;
+
+  // If we get another BeginFrame before the previous deadline,
+  // synchronously trigger the previous deadline before progressing.
+  if (inside_begin_frame_deadline_interval_) {
+    OnBeginFrameDeadline();
+  }
+
+  // Schedule the deadline.
+  current_begin_frame_args_ = args;
+  current_begin_frame_args_.deadline = adjusted_deadline;
+  inside_begin_frame_deadline_interval_ = true;
+  ScheduleBeginFrameDeadline();
+
+  return true;
+}
+
+base::TimeTicks DisplayScheduler::DesiredBeginFrameDeadlineTime() {
+  if (output_surface_lost_) {
+    TRACE_EVENT_INSTANT0("cc", "Lost output surface", TRACE_EVENT_SCOPE_THREAD);
+    return base::TimeTicks();
+  }
+
+  if (pending_swaps_ >= max_pending_swaps_) {
+    TRACE_EVENT_INSTANT0("cc", "Swap throttled", TRACE_EVENT_SCOPE_THREAD);
+    return base::TimeTicks();
+  }
+
+  if (!needs_draw_) {
+    TRACE_EVENT_INSTANT0("cc", "No damage yet", TRACE_EVENT_SCOPE_THREAD);
+    return current_begin_frame_args_.frame_time +
+           current_begin_frame_args_.interval;
+  }
+
+  if (root_surface_resources_locked_) {
+    TRACE_EVENT_INSTANT0("cc", "Root surface resources locked",
+                         TRACE_EVENT_SCOPE_THREAD);
+    return current_begin_frame_args_.frame_time +
+           current_begin_frame_args_.interval;
+  }
+
+  // TODO(mithro): Be smarter about resize deadlines.
+  if (entire_display_damaged_) {
+    TRACE_EVENT_INSTANT0("cc", "Entire display damaged",
+                         TRACE_EVENT_SCOPE_THREAD);
+    return base::TimeTicks();
+  }
+
+  bool root_ready_to_draw =
+      !expect_damage_from_root_surface_ || root_surface_damaged_;
+
+  if (all_active_child_surfaces_ready_to_draw_ && root_ready_to_draw) {
+    TRACE_EVENT_INSTANT0("cc", "All active surfaces ready",
+                         TRACE_EVENT_SCOPE_THREAD);
+    return base::TimeTicks();
+  }
+
+  // Use an earlier deadline if we are only waiting for the root surface
+  // in case our expect_damage_from_root_surface heuristic is incorrect.
+  // TODO(mithro): Replace this with SetNeedsBeginFrame and SwapAbort
+  // logic.
+  if (all_active_child_surfaces_ready_to_draw_ &&
+      expect_damage_from_root_surface_) {
+    TRACE_EVENT_INSTANT0("cc", "Waiting for damage from root surface",
+                         TRACE_EVENT_SCOPE_THREAD);
+    // This adjusts the deadline by DefaultEstimatedParentDrawTime for
+    // a second time. The first one represented the Surfaces draw to display
+    // latency. This one represents root surface commit+raster+draw latency.
+    // We treat the root surface differently since it lives on the same thread
+    // as Surfaces and waiting for it too long may push out the Surfaces draw.
+    // If we also assume the root surface is fast to start a commit after the
+    // beginning of a frame, it'll have a chance to lock its resources, which
+    // will cause us to wait for it to unlock its resources above.
+    // TODO(mithro): Replace hard coded estimates.
+    return current_begin_frame_args_.deadline -
+           BeginFrameArgs::DefaultEstimatedParentDrawTime();
+  }
+
+  TRACE_EVENT_INSTANT0("cc", "More damage expected soon",
+                       TRACE_EVENT_SCOPE_THREAD);
+  return current_begin_frame_args_.deadline;
+}
+
+void DisplayScheduler::ScheduleBeginFrameDeadline() {
+  TRACE_EVENT0("cc", "DisplayScheduler::ScheduleBeginFrameDeadline");
+
+  // We need to wait for the next BeginFrame before scheduling a deadline.
+  if (!inside_begin_frame_deadline_interval_) {
+    TRACE_EVENT_INSTANT0("cc", "Waiting for next BeginFrame",
+                         TRACE_EVENT_SCOPE_THREAD);
+    DCHECK(begin_frame_deadline_task_.IsCancelled());
+    return;
+  }
+
+  // Determine the deadline we want to use.
+  base::TimeTicks desired_deadline = DesiredBeginFrameDeadlineTime();
+
+  // Avoid re-scheduling the deadline if it's already correctly scheduled.
+  if (!begin_frame_deadline_task_.IsCancelled() &&
+      desired_deadline == begin_frame_deadline_task_time_) {
+    TRACE_EVENT_INSTANT0("cc", "Using existing deadline",
+                         TRACE_EVENT_SCOPE_THREAD);
+    return;
+  }
+
+  // Schedule the deadline.
+  begin_frame_deadline_task_time_ = desired_deadline;
+  begin_frame_deadline_task_.Cancel();
+  begin_frame_deadline_task_.Reset(begin_frame_deadline_closure_);
+
+  base::TimeDelta delta =
+      std::max(base::TimeDelta(), desired_deadline - gfx::FrameTime::Now());
+  task_runner_->PostDelayedTask(FROM_HERE,
+                                begin_frame_deadline_task_.callback(), delta);
+  TRACE_EVENT2("cc", "Using new deadline", "delta", delta.ToInternalValue(),
+               "desired_deadline", desired_deadline);
+}
+
+void DisplayScheduler::OnBeginFrameDeadline() {
+  TRACE_EVENT0("cc", "DisplayScheduler::OnBeginFrameDeadline");
+  inside_begin_frame_deadline_interval_ = false;
+  begin_frame_deadline_task_.Cancel();
+  begin_frame_deadline_task_time_ = base::TimeTicks();
+
+  if (needs_draw_ && !output_surface_lost_) {
+    if (pending_swaps_ < max_pending_swaps_ && !root_surface_resources_locked_)
+      DrawAndSwap();
+  } else {
+    begin_frame_source_->SetNeedsBeginFrames(false);
+  }
+
+  begin_frame_source_->DidFinishFrame(0);
+}
+
+void DisplayScheduler::DidSwapBuffers() {
+  pending_swaps_++;
+  TRACE_EVENT1("cc", "DisplayScheduler::DidSwapBuffers", "pending_frames",
+               pending_swaps_);
+}
+
+void DisplayScheduler::DidSwapBuffersComplete() {
+  pending_swaps_--;
+  TRACE_EVENT1("cc", "DisplayScheduler::DidSwapBuffersComplete",
+               "pending_frames", pending_swaps_);
+  ScheduleBeginFrameDeadline();
+}
+
+}  // namespace cc