| // 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 CONTENT_RENDERER_SCHEDULER_RESOURCE_DISPATCH_THROTTLER_H_ |
| #define CONTENT_RENDERER_SCHEDULER_RESOURCE_DISPATCH_THROTTLER_H_ |
| |
| #include <deque> |
| |
| #include "base/threading/thread_checker.h" |
| #include "base/time/time.h" |
| #include "base/timer/timer.h" |
| #include "content/common/content_export.h" |
| #include "ipc/ipc_sender.h" |
| |
| namespace content { |
| |
| class RendererScheduler; |
| |
| // Utility class for throttling a stream of resource requests targetted to a |
| // specific IPC sender. The throttling itself is very basic: |
| // * When there is no high-priority work imminent to the main thread, as |
| // indicated by the RendererScheduler, throttling is disabled. |
| // * When >= N requests have been sent in a given time window, requests are |
| // throttled. A timer periodically flushes a portion of the queued requests |
| // until all such requests have been flushed. |
| // TODO(jdduke): Remove this class after resource requests become sufficiently |
| // cheap on the IO thread, crbug.com/440037. |
| class CONTENT_EXPORT ResourceDispatchThrottler : public IPC::Sender { |
| public: |
| // |flush_period| and |max_requests_per_flush| must be strictly positive |
| // in duration/value. |
| ResourceDispatchThrottler(IPC::Sender* proxied_sender, |
| RendererScheduler* scheduler, |
| base::TimeDelta flush_period, |
| uint32 max_requests_per_flush); |
| ~ResourceDispatchThrottler() override; |
| |
| // IPC::Sender implementation: |
| bool Send(IPC::Message* msg) override; |
| |
| private: |
| friend class ResourceDispatchThrottlerForTest; |
| |
| // Virtual for testing. |
| virtual base::TimeTicks Now() const; |
| virtual void ScheduleFlush(); |
| |
| void Flush(); |
| void FlushAll(); |
| bool ForwardMessage(IPC::Message* msg); |
| |
| base::ThreadChecker thread_checker_; |
| |
| IPC::Sender* const proxied_sender_; |
| RendererScheduler* const scheduler_; |
| const base::TimeDelta flush_period_; |
| const uint32 max_requests_per_flush_; |
| |
| base::Timer flush_timer_; |
| base::TimeTicks last_sent_request_time_; |
| uint32 sent_requests_since_last_flush_; |
| std::deque<IPC::Message*> throttled_messages_; |
| |
| DISALLOW_COPY_AND_ASSIGN(ResourceDispatchThrottler); |
| }; |
| |
| } // namespace content |
| |
| #endif // CONTENT_RENDERER_SCHEDULER_RESOURCE_DISPATCH_THROTTLER_H_ |