1 /*
2  *  Copyright (c) 2011 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #ifndef MODULES_UTILITY_SOURCE_PROCESS_THREAD_IMPL_H_
12 #define MODULES_UTILITY_SOURCE_PROCESS_THREAD_IMPL_H_
13 
14 #include <stdint.h>
15 
16 #include <list>
17 #include <memory>
18 #include <queue>
19 
20 #include "api/task_queue/queued_task.h"
21 #include "modules/include/module.h"
22 #include "modules/utility/include/process_thread.h"
23 #include "rtc_base/deprecated/recursive_critical_section.h"
24 #include "rtc_base/event.h"
25 #include "rtc_base/location.h"
26 #include "rtc_base/platform_thread.h"
27 #include "rtc_base/thread_checker.h"
28 
29 namespace webrtc {
30 
31 class ProcessThreadImpl : public ProcessThread {
32  public:
33   explicit ProcessThreadImpl(const char* thread_name);
34   ~ProcessThreadImpl() override;
35 
36   void Start() override;
37   void Stop() override;
38 
39   void WakeUp(Module* module) override;
40   void PostTask(std::unique_ptr<QueuedTask> task) override;
41   void PostDelayedTask(std::unique_ptr<QueuedTask> task,
42                        uint32_t milliseconds) override;
43 
44   void RegisterModule(Module* module, const rtc::Location& from) override;
45   void DeRegisterModule(Module* module) override;
46 
47  protected:
48   static void Run(void* obj);
49   bool Process();
50 
51  private:
52   struct ModuleCallback {
53     ModuleCallback() = delete;
54     ModuleCallback(ModuleCallback&& cb) = default;
55     ModuleCallback(const ModuleCallback& cb) = default;
ModuleCallbackModuleCallback56     ModuleCallback(Module* module, const rtc::Location& location)
57         : module(module), location(location) {}
58     bool operator==(const ModuleCallback& cb) const {
59       return cb.module == module;
60     }
61 
62     Module* const module;
63     int64_t next_callback = 0;  // Absolute timestamp.
64     const rtc::Location location;
65 
66    private:
67     ModuleCallback& operator=(ModuleCallback&);
68   };
69   struct DelayedTask {
DelayedTaskDelayedTask70     DelayedTask(int64_t run_at_ms, std::unique_ptr<QueuedTask> task)
71         : run_at_ms(run_at_ms), task(task.release()) {}
72     friend bool operator<(const DelayedTask& lhs, const DelayedTask& rhs) {
73       // Earliest DelayedTask should be at the top of the priority queue.
74       return lhs.run_at_ms > rhs.run_at_ms;
75     }
76 
77     int64_t run_at_ms;
78     // DelayedTask owns the |task|, but some delayed tasks must be removed from
79     // the std::priority_queue, but mustn't be deleted. std::priority_queue does
80     // not give non-const access to the values, so storing unique_ptr would
81     // delete the task as soon as it is remove from the priority queue.
82     // Thus lifetime of the |task| is managed manually.
83     QueuedTask* task;
84   };
85   typedef std::list<ModuleCallback> ModuleList;
86 
87   void Delete() override;
88 
89   // Warning: For some reason, if |lock_| comes immediately before |modules_|
90   // with the current class layout, we will  start to have mysterious crashes
91   // on Mac 10.9 debug.  I (Tommi) suspect we're hitting some obscure alignemnt
92   // issues, but I haven't figured out what they are, if there are alignment
93   // requirements for mutexes on Mac or if there's something else to it.
94   // So be careful with changing the layout.
95   rtc::RecursiveCriticalSection
96       lock_;  // Used to guard modules_, tasks_ and stop_.
97 
98   rtc::ThreadChecker thread_checker_;
99   rtc::Event wake_up_;
100   // TODO(pbos): Remove unique_ptr and stop recreating the thread.
101   std::unique_ptr<rtc::PlatformThread> thread_;
102 
103   ModuleList modules_;
104   std::queue<QueuedTask*> queue_;
105   std::priority_queue<DelayedTask> delayed_tasks_ RTC_GUARDED_BY(lock_);
106   bool stop_;
107   const char* thread_name_;
108 };
109 
110 }  // namespace webrtc
111 
112 #endif  // MODULES_UTILITY_SOURCE_PROCESS_THREAD_IMPL_H_
113