[scheduler] Move TimeBudgetPool to a separate file.

third_party/WebKit/Source/platform/scheduler/renderer/budget_pool.h

+// Copyright 2017 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_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_BUDGET_POOL_H_
+#define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_BUDGET_POOL_H_
+
+#include <unordered_set>
+
+#include "base/callback.h"
+#include "base/gtest_prod_util.h"
+#include "base/macros.h"
+#include "base/optional.h"
+#include "base/time/time.h"
+#include "platform/scheduler/base/lazy_now.h"
+
+namespace base {
+namespace trace_event {
+class TracedValue;
+}
+}
+
+namespace blink {
+namespace scheduler {
+
+class TaskQueue;
+class TaskQueueThrottler;
+
+// BudgetPool represents a group of task queues which share a limit
+// on a resource. This limit applies when task queues are already throttled
+// by TaskQueueThrottler.
+class BudgetPool {
+ public:
+  virtual ~BudgetPool();
+
+  virtual const char* Name() const = 0;
+
+  // Adds |queue| to given pool. If the pool restriction does not allow
+  // a task to be run immediately and |queue| is throttled, |queue| becomes
+  // disabled.
+  virtual void AddQueue(base::TimeTicks now, TaskQueue* queue) = 0;
+
+  // Removes |queue| from given pool. If it is throttled, it does not
+  // become enabled immediately, but a call to |PumpThrottledTasks|
+  // is scheduled.
+  virtual void RemoveQueue(base::TimeTicks now, TaskQueue* queue) = 0;
+
+  // Enables this time budget pool. Queues from this pool will be
+  // throttled based on their run time.
+  virtual void EnableThrottling(LazyNow* now) = 0;
+
+  // Disables with time budget pool. Queues from this pool will not be
+  // throttled based on their run time. A call to |PumpThrottledTasks|
+  // will be scheduled to enable this queues back again and respect
+  // timer alignment. Internal budget level will not regenerate with time.
+  virtual void DisableThrottling(LazyNow* now) = 0;
+
+  virtual bool IsThrottlingEnabled() const = 0;
+
+  // Report task run time to the budget pool.
+  virtual void RecordTaskRunTime(base::TimeTicks start_time,
+                                 base::TimeTicks end_time) = 0;
+
+  // All queues should be removed before calling Close().
+  virtual void Close() = 0;
+
+  // Returns true at a task can be run immediately at the given time.
+  virtual bool HasEnoughBudgetToRun(base::TimeTicks now) = 0;
+
+  // Retuns earliest time (can be in the past) when the next task can run.
+  virtual base::TimeTicks GetNextAllowedRunTime() = 0;
+
+  // Returns state for tracing.
+  virtual void AsValueInto(base::trace_event::TracedValue* state,
+                           base::TimeTicks now) const = 0;
+};
+
+// TimeBudgetPool represents a collection of task queues which share a limit
+// on total cpu time.
+class TimeBudgetPool : public BudgetPool {
+ public:
+  ~TimeBudgetPool();
+
+  // Throttle task queues from this time budget pool if tasks are running
+  // for more than |cpu_percentage| per cent of wall time.
+  // This function does not affect internal time budget level.
+  void SetTimeBudgetRecoveryRate(base::TimeTicks now, double cpu_percentage);
+
+  // Increase budget level by given value. This function DOES NOT unblock
+  // queues even if they are allowed to run with increased budget level.
+  void GrantAdditionalBudget(base::TimeTicks now, base::TimeDelta budget_level);
+
+  // Set callback which will be called every time when this budget pool
+  // is throttled. Throttling duration (time until the queue is allowed
+  // to run again) is passed as a parameter to callback.
+  void SetReportingCallback(
+      base::Callback<void(base::TimeDelta)> reporting_callback);
+
+  // BudgetPool implementation:
+  const char* Name() const override;
+  void AddQueue(base::TimeTicks now, TaskQueue* queue) override;
+  void RemoveQueue(base::TimeTicks now, TaskQueue* queue) override;
+  void EnableThrottling(LazyNow* now) override;
+  void DisableThrottling(LazyNow* now) override;
+  bool IsThrottlingEnabled() const override;
+  void RecordTaskRunTime(base::TimeTicks start_time,
+                         base::TimeTicks end_time) override;
+  void Close() override;
+  bool HasEnoughBudgetToRun(base::TimeTicks now) override;
+  base::TimeTicks GetNextAllowedRunTime() override;
+  void AsValueInto(base::trace_event::TracedValue* state,
+                   base::TimeTicks now) const override;
+
+ private:
+  friend class TaskQueueThrottler;
+
+  FRIEND_TEST_ALL_PREFIXES(TaskQueueThrottlerTest, TimeBudgetPool);
+
+  TimeBudgetPool(const char* name,
+                 TaskQueueThrottler* task_queue_throttler,
+                 base::TimeTicks now,
+                 base::Optional<base::TimeDelta> max_budget_level,
+                 base::Optional<base::TimeDelta> max_throttling_duration);
+
+  // Advances |last_checkpoint_| to |now| if needed and recalculates
+  // budget level.
+  void Advance(base::TimeTicks now);
+
+  // Disable all associated throttled queues.
+  void BlockThrottledQueues(base::TimeTicks now);
+
+  // Increase |current_budget_level_| to satisfy max throttling duration
+  // condition if necessary.
+  // Decrease |current_budget_level_| to satisfy max budget level
+  // condition if necessary.
+  void EnforceBudgetLevelRestrictions();
+
+  const char* name_;  // NOT OWNED
+
+  TaskQueueThrottler* task_queue_throttler_;
+
+  // Max budget level which we can accrue.
+  // Tasks will be allowed to run for this time before being throttled
+  // after a very long period of inactivity.
+  base::Optional<base::TimeDelta> max_budget_level_;
+  // Max throttling duration places a lower limit on time budget level,
+  // ensuring that one long task does not cause extremely long throttling.
+  // Note that this is not the guarantee that every task will run
+  // after desired run time + max throttling duration, but a guarantee
+  // that at least one task will be run every max_throttling_duration.
+  base::Optional<base::TimeDelta> max_throttling_duration_;
+
+  base::TimeDelta current_budget_level_;
+  base::TimeTicks last_checkpoint_;
+  double cpu_percentage_;
+  bool is_enabled_;
+
+  std::unordered_set<TaskQueue*> associated_task_queues_;
+
+  base::Callback<void(base::TimeDelta)> reporting_callback_;
+
+  DISALLOW_COPY_AND_ASSIGN(TimeBudgetPool);
+};
+
+}  // namespace scheduler
+}  // namespace blink
+
+#endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_BUDGET_POOL_H_