blob: 3ccc788a8ac6655653f40d9d5cc628cdd2105bba [file] [log] [blame]
// 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.
#include <stdint.h>
#include <deque>
#include "base/macros.h"
#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 blink {
namespace scheduler {
class RendererScheduler;
namespace content {
// 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,
class CONTENT_EXPORT ResourceDispatchThrottler : public IPC::Sender {
// |flush_period| and |max_requests_per_flush| must be strictly positive
// in duration/value.
ResourceDispatchThrottler(IPC::Sender* proxied_sender,
blink::scheduler::RendererScheduler* scheduler,
base::TimeDelta flush_period,
uint32_t max_requests_per_flush);
~ResourceDispatchThrottler() override;
// IPC::Sender implementation:
bool Send(IPC::Message* msg) override;
friend class ResourceDispatchThrottlerForTest;
// Virtual for testing.
virtual base::TimeTicks Now() const;
virtual void ScheduleFlush();
void Flush();
void FlushAll();
void LogFlush();
bool ForwardMessage(IPC::Message* msg);
base::ThreadChecker thread_checker_;
IPC::Sender* const proxied_sender_;
blink::scheduler::RendererScheduler* const scheduler_;
const base::TimeDelta flush_period_;
const uint32_t max_requests_per_flush_;
base::Timer flush_timer_;
base::TimeTicks last_flush_time_;
uint32_t sent_requests_since_last_flush_;
std::deque<IPC::Message*> throttled_messages_;
} // namespace content