1// Copyright 2014 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef CHROME_BROWSER_SAFE_BROWSING_INCIDENT_REPORTING_DELAYED_CALLBACK_RUNNER_H_
6#define CHROME_BROWSER_SAFE_BROWSING_INCIDENT_REPORTING_DELAYED_CALLBACK_RUNNER_H_
7
8#include <list>
9
10#include "base/callback_forward.h"
11#include "base/macros.h"
12#include "base/memory/ref_counted.h"
13#include "base/task_runner.h"
14#include "base/threading/thread_checker.h"
15#include "base/time/time.h"
16#include "base/timer/timer.h"
17
18namespace safe_browsing {
19
20// Runs callbacks on a given task runner, waiting a certain amount of time
21// between each. The delay also applies to running the first callback (i.e.,
22// the first callback will be run some time after Start() is invoked). Callbacks
23// are deleted after they are run. Start() is idempotent: calling it while the
24// runner is doing its job has no effect.
25class DelayedCallbackRunner {
26 public:
27  // Constructs an instance that runs tasks on |callback_runner|, waiting for
28  // |delay| time to pass before and between each callback.
29  DelayedCallbackRunner(base::TimeDelta delay,
30                        const scoped_refptr<base::TaskRunner>& task_runner);
31  ~DelayedCallbackRunner();
32
33  // Registers |callback| with the runner. A copy of |callback| is held until it
34  // is run.
35  void RegisterCallback(const base::Closure& callback);
36
37  // Starts running the callbacks after the delay.
38  void Start();
39
40 private:
41  typedef std::list<base::Closure> CallbackList;
42
43  // A callback invoked by the timer to run the next callback. The timer is
44  // restarted to process the next callback if there is one.
45  void OnTimer();
46
47  base::ThreadChecker thread_checker_;
48
49  // The runner on which callbacks are to be run.
50  scoped_refptr<base::TaskRunner> task_runner_;
51
52  // The list of callbacks to run. Callbacks are removed when run.
53  CallbackList callbacks_;
54
55  // callbacks_.end() when no work is being done. Any other value otherwise.
56  CallbackList::iterator next_callback_;
57
58  // A timer upon the firing of which the next callback will be run.
59  base::DelayTimer<DelayedCallbackRunner> timer_;
60
61  DISALLOW_COPY_AND_ASSIGN(DelayedCallbackRunner);
62};
63
64}  // namespace safe_browsing
65
66#endif  // CHROME_BROWSER_SAFE_BROWSING_INCIDENT_REPORTING_DELAYED_CALLBACK_RUNNER_H_
67