1/*
2 * libjingle
3 * Copyright 2004--2006, Google Inc.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 *  1. Redistributions of source code must retain the above copyright notice,
9 *     this list of conditions and the following disclaimer.
10 *  2. Redistributions in binary form must reproduce the above copyright notice,
11 *     this list of conditions and the following disclaimer in the documentation
12 *     and/or other materials provided with the distribution.
13 *  3. The name of the author may not be used to endorse or promote products
14 *     derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
17 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
18 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
19 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
20 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28#ifndef TALK_BASE_TASKRUNNER_H__
29#define TALK_BASE_TASKRUNNER_H__
30
31#include <vector>
32
33#include "talk/base/basictypes.h"
34#include "talk/base/sigslot.h"
35#include "talk/base/taskparent.h"
36
37namespace talk_base {
38class Task;
39
40const int64 kSecToMsec = 1000;
41const int64 kMsecTo100ns = 10000;
42const int64 kSecTo100ns = kSecToMsec * kMsecTo100ns;
43
44class TaskRunner : public TaskParent, public sigslot::has_slots<> {
45 public:
46  TaskRunner();
47  virtual ~TaskRunner();
48
49  virtual void WakeTasks() = 0;
50
51  // Returns the current time in 100ns units.  It is used for
52  // determining timeouts.  The origin is not important, only
53  // the units and that rollover while the computer is running.
54  //
55  // On Windows, GetSystemTimeAsFileTime is the typical implementation.
56  virtual int64 CurrentTime() = 0 ;
57
58  void StartTask(Task *task);
59  void RunTasks();
60  void PollTasks();
61
62  void UpdateTaskTimeout(Task *task, int64 previous_task_timeout_time);
63
64#ifdef _DEBUG
65  bool is_ok_to_delete(Task* task) {
66    return task == deleting_task_;
67  }
68
69  void IncrementAbortCount() {
70    ++abort_count_;
71  }
72
73  void DecrementAbortCount() {
74    --abort_count_;
75  }
76#endif
77
78  // Returns the next absolute time when a task times out
79  // OR "0" if there is no next timeout.
80  int64 next_task_timeout() const;
81
82 protected:
83  // The primary usage of this method is to know if
84  // a callback timer needs to be set-up or adjusted.
85  // This method will be called
86  //  * when the next_task_timeout() becomes a smaller value OR
87  //  * when next_task_timeout() has changed values and the previous
88  //    value is in the past.
89  //
90  // If the next_task_timeout moves to the future, this method will *not*
91  // get called (because it subclass should check next_task_timeout()
92  // when its timer goes off up to see if it needs to set-up a new timer).
93  //
94  // Note that this maybe called conservatively.  In that it may be
95  // called when no time change has happened.
96  virtual void OnTimeoutChange() {
97    // by default, do nothing.
98  }
99
100 private:
101  void InternalRunTasks(bool in_destructor);
102  void CheckForTimeoutChange(int64 previous_timeout_time);
103
104  std::vector<Task *> tasks_;
105  Task *next_timeout_task_;
106  bool tasks_running_;
107#ifdef _DEBUG
108  int abort_count_;
109  Task* deleting_task_;
110#endif
111
112  void RecalcNextTimeout(Task *exclude_task);
113};
114
115} // namespace talk_base
116
117#endif  // TASK_BASE_TASKRUNNER_H__
118