[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

[alex clarke (OOO till 29th), 2017/03/09 12:33:05]

Maybe mention that the resource is measured in time?

+// by TaskQueueThrottler.
+class BudgetPool {
+ public:
+   ~BudgetPool();

[Sami, 2017/03/08 16:18:01]

virtual

[altimin, 2017/03/08 16:50:33]

Shame. Shame. Shame.

+
+   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;

[alex clarke (OOO till 29th), 2017/03/09 12:33:05]

Does this need to be virtual? Could it be:

bool HasEnoughBudgetToRun(base::TimeTicks now) const {
  return now >= GetNextAllowedRunTime();
}

[altimin, 2017/03/09 13:36:02]

At this moment HasEnoughBudgetToRun updates last known time. It may be worth
changing, but I don't want to do it in this patch.

+
+   // 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;

[Sami, 2017/03/08 16:18:01]

Is this formatted right?

[altimin, 2017/03/08 16:50:32]

Done.

[alex clarke (OOO till 29th), 2017/03/09 12:33:05]

nit: indent looks odd.

+};
+
+// TimeBudgetPool represents a collection of task queues which share a limit
+// on total cpu time.
+class TimeBudgetPool : public BudgetPool {

[alex clarke (OOO till 29th), 2017/03/09 12:33:05]

bike-shed: CpuTimeBudgetPool?  I was wondering why BudgetPool knew about times
when there was a TimeBidget pool.

[altimin, 2017/03/09 13:36:02]

Done.

+ 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;

[Sami, 2017/03/08 16:18:01]

Line too long?

[altimin, 2017/03/08 16:50:32]

Done.

+
+ 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_