[scheduler] Untangle BudgetPool from TaskQueueThrottler.

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

 // 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.
 
 #ifndef THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_TASK_QUEUE_THROTTLER_H_
 #define THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_TASK_QUEUE_THROTTLER_H_
 
 #include <set>
 #include <unordered_map>
 
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/optional.h"
 #include "base/threading/thread_checker.h"
 #include "platform/scheduler/base/cancelable_closure_holder.h"
 #include "platform/scheduler/base/time_domain.h"
+#include "platform/scheduler/renderer/budget_pool.h"
 #include "public/platform/WebViewScheduler.h"
 
 namespace base {
 namespace trace_event {
 class TracedValue;
 }
 }
 
 namespace blink {
 namespace scheduler {
 
 class BudgetPool;
 class RendererSchedulerImpl;
 class ThrottledTimeDomain;
 class CPUTimeBudgetPool;
 
+// Interface for BudgetPool to interact with TaskQueueThrottler.
+class BLINK_PLATFORM_EXPORT BudgetPoolController {
+ public:
+  virtual ~BudgetPoolController() {}
+
+  // To be used by BudgetPool only, use BudgetPool::{Add,Remove}Queue
+  // methods instead.
+  virtual void AddQueueToBudgetPool(TaskQueue* queue,
+                                    BudgetPool* budget_pool) = 0;
+  virtual void RemoveQueueFromBudgetPool(TaskQueue* queue,
+                                         BudgetPool* budget_pool) = 0;
+
+  // Deletes the budget pool.
+  virtual void UnregisterBudgetPool(BudgetPool* budget_pool) = 0;
+
+  // Insert a fence to prevent tasks from running and schedule a wakeup at
+  // an appropriate time.
+  virtual void BlockQueue(base::TimeTicks now, TaskQueue* queue) = 0;
+
+  // Schedule a call to unblock queue at an appropriate moment.
+  virtual void UnblockQueue(base::TimeTicks now, TaskQueue* queue) = 0;
+
+  // Returns true if the |queue| is throttled (i.e. added to TaskQueueThrottler
+  // and throttling is not disabled).
+  virtual bool IsThrottled(TaskQueue* queue) const = 0;
+};
+
 // The job of the TaskQueueThrottler is to control when tasks posted on
 // throttled queues get run. The TaskQueueThrottler:
 // - runs throttled tasks once per second,
 // - controls time budget for task queues grouped in CPUTimeBudgetPools.
 //
 // This is done by disabling throttled queues and running
 // a special "heart beat" function |PumpThrottledTasks| which when run
 // temporarily enables throttled queues and inserts a fence to ensure tasks
 // posted from a throttled task run next time the queue is pumped.
 //
 // Of course the TaskQueueThrottler isn't the only sub-system that wants to
 // enable or disable queues. E.g. RendererSchedulerImpl also does this for
 // policy reasons. To prevent the systems from fighting, clients of
 // TaskQueueThrottler must use SetQueueEnabled rather than calling the function
 // directly on the queue.
 //
 // There may be more than one system that wishes to throttle a queue (e.g.
 // renderer suspension vs tab level suspension) so the TaskQueueThrottler keeps
 // a count of the number of systems that wish a queue to be throttled.
 // See IncreaseThrottleRefCount & DecreaseThrottleRefCount.
 //
 // This class is main-thread only.
-class BLINK_PLATFORM_EXPORT TaskQueueThrottler : public TimeDomain::Observer {
+class BLINK_PLATFORM_EXPORT TaskQueueThrottler : public TimeDomain::Observer,
+                                                 BudgetPoolController {

[Sami, 2017/03/15 15:08:08]

nit: public inheritance plz

[altimin, 2017/03/15 18:20:56]

Done.

  public:
   // TODO(altimin): Do not pass tracing category as const char*,
   // hard-code string instead.
   TaskQueueThrottler(RendererSchedulerImpl* renderer_scheduler,
                      const char* tracing_category);
 
   ~TaskQueueThrottler() override;
 
   // TimeDomain::Observer implementation:
   void OnTimeDomainHasImmediateWork(TaskQueue*) override;
   void OnTimeDomainHasDelayedWork(TaskQueue*) override;
 
+  // BudgetPoolController implementation:
+  void AddQueueToBudgetPool(TaskQueue* queue, BudgetPool* budget_pool) override;
+  void RemoveQueueFromBudgetPool(TaskQueue* queue,
+                                 BudgetPool* budget_pool) override;
+  void UnregisterBudgetPool(BudgetPool* budget_pool) override;
+  void BlockQueue(base::TimeTicks now, TaskQueue* queue) override;
+  void UnblockQueue(base::TimeTicks now, TaskQueue* queue) override;
+  bool IsThrottled(TaskQueue* queue) const override;
+
   // Increments the throttled refcount and causes |task_queue| to be throttled
   // if its not already throttled.
   void IncreaseThrottleRefCount(TaskQueue* task_queue);
 
   // If the refcouint is non-zero it's decremented.  If the throttled refcount
   // becomes zero then |task_queue| is unthrottled.  If the refcount was already
   // zero this function does nothing.
   void DecreaseThrottleRefCount(TaskQueue* task_queue);
 
   // Removes |task_queue| from |queue_details| and from appropriate budget pool.
   void UnregisterTaskQueue(TaskQueue* task_queue);
 
-  // Returns true if the |task_queue| is throttled.
-  bool IsThrottled(TaskQueue* task_queue) const;
-
   // Disable throttling for all queues, this setting takes precedence over
   // all other throttling settings. Designed to be used when a global event
   // disabling throttling happens (e.g. audio is playing).
   void DisableThrottling();
 
   // Enable back global throttling.
   void EnableThrottling();
 
   const ThrottledTimeDomain* time_domain() const { return time_domain_.get(); }
 
   static base::TimeTicks AlignedThrottledRunTime(
       base::TimeTicks unthrottled_runtime);
 
   const scoped_refptr<TaskQueue>& task_runner() const { return task_runner_; }
 
   // Returned object is owned by |TaskQueueThrottler|.
   CPUTimeBudgetPool* CreateCPUTimeBudgetPool(
       const char* name,
       base::Optional<base::TimeDelta> max_budget_level,
       base::Optional<base::TimeDelta> max_throttling_duration);
 
   // Accounts for given task for cpu-based throttling needs.
   void OnTaskRunTimeReported(TaskQueue* task_queue,
                              base::TimeTicks start_time,
                              base::TimeTicks end_time);
 
   void AsValueInto(base::trace_event::TracedValue* state,
                    base::TimeTicks now) const;
-
  private:
-  friend class BudgetPool;
-  friend class CPUTimeBudgetPool;
-
   struct Metadata {
-    Metadata() : throttling_ref_count(0), time_budget_pool(nullptr) {}
+    Metadata() : throttling_ref_count(0), budget_pool(nullptr) {}
 
     size_t throttling_ref_count;
 
-    CPUTimeBudgetPool* time_budget_pool;
+    BudgetPool* budget_pool;
   };
   using TaskQueueMap = std::unordered_map<TaskQueue*, Metadata>;
 
   void PumpThrottledTasks();
 
   // Note |unthrottled_runtime| might be in the past. When this happens we
   // compute the delay to the next runtime based on now rather than
   // unthrottled_runtime.
   void MaybeSchedulePumpThrottledTasks(
       const tracked_objects::Location& from_here,
       base::TimeTicks now,
       base::TimeTicks runtime);
 
-  CPUTimeBudgetPool* GetTimeBudgetPoolForQueue(TaskQueue* queue);
-
-  // Schedule pumping because of given task queue.
-  void MaybeSchedulePumpQueue(
-      const tracked_objects::Location& from_here,
-      base::TimeTicks now,
-      TaskQueue* queue,
-      base::Optional<base::TimeTicks> next_possible_run_time);
+  BudgetPool* GetBudgetPoolForQueue(TaskQueue* queue);
 
   // Return next possible time when queue is allowed to run in accordance
   // with throttling policy.
   base::TimeTicks GetNextAllowedRunTime(base::TimeTicks now, TaskQueue* queue);
 
   void MaybeDeleteQueueMetadata(TaskQueueMap::iterator it);
 
+  // Schedule a call PumpThrottledTasks at an appropriate moment for this queue.
+  void SchedulePumpQueue(const tracked_objects::Location& from_here,
+                         base::TimeTicks now,
+                         TaskQueue* queue);
+
   TaskQueueMap queue_details_;
   base::Callback<void(TaskQueue*)> forward_immediate_work_callback_;
   scoped_refptr<TaskQueue> task_runner_;
   RendererSchedulerImpl* renderer_scheduler_;  // NOT OWNED
   base::TickClock* tick_clock_;                // NOT OWNED
   const char* tracing_category_;               // NOT OWNED
   std::unique_ptr<ThrottledTimeDomain> time_domain_;
 
   CancelableClosureHolder pump_throttled_tasks_closure_;
   base::Optional<base::TimeTicks> pending_pump_throttled_tasks_runtime_;
   bool allow_throttling_;
 
-  std::unordered_map<BudgetPool*, std::unique_ptr<BudgetPool>>
-      time_budget_pools_;
+  std::unordered_map<BudgetPool*, std::unique_ptr<BudgetPool>> budget_pools_;
 
   base::WeakPtrFactory<TaskQueueThrottler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(TaskQueueThrottler);
 };
 
 }  // namespace scheduler
 }  // namespace blink
 
 #endif  // THIRD_PARTY_WEBKIT_SOURCE_PLATFORM_SCHEDULER_RENDERER_TASK_QUEUE_THROTTLER_H_