third_party/blink/renderer/core/display_lock/yielding_display_lock_budget.h

// Copyright 2018 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.

#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_DISPLAY_LOCK_YIELDING_DISPLAY_LOCK_BUDGET_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_DISPLAY_LOCK_YIELDING_DISPLAY_LOCK_BUDGET_H_

#include "base/optional.h"
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/display_lock/display_lock_budget.h"
#include "third_party/blink/renderer/platform/wtf/time.h"

namespace blink {

// This budget yields between lifecycle phases even if that phase is quick. In
// other words, it will only do one new lifecycle phase at a time, and block the
// future ones. Any lifecycle phases that have already been allowed by this
// budget in the past are not blocked.
class CORE_EXPORT YieldingDisplayLockBudget final : public DisplayLockBudget {
 public:
  YieldingDisplayLockBudget(DisplayLockContext*);
  ~YieldingDisplayLockBudget() override = default;

  bool ShouldPerformPhase(Phase) const override;
  void DidPerformPhase(Phase) override;
  void WillStartLifecycleUpdate() override;
  // Returns true if any of the lifecycles that have been previously blocked by
  // this budget need updates. Note that this does not check lifecycle phases
  // that have already completed by this budget even if they are now dirty
  // again. This is done to prevent starvation (ie, it is possible for the
  // budget to always schedule more work if something in rAF keeps dirtying
  // layout, for example).
  bool NeedsLifecycleUpdates() const override;

 protected:
  friend class DisplayLockBudgetTest;

  double GetCurrentBudgetMs() const;

  int lifecycle_count_ = 0;
  TimeTicks deadline_;
  base::Optional<Phase> last_completed_phase_;
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_CORE_DISPLAY_LOCK_YIELDING_DISPLAY_LOCK_BUDGET_H_