aboutsummaryrefslogtreecommitdiff
path: root/test/src/utils/TaskDispatcher.h
blob: bd8bfc8ea721c35598017058c586e138c976bd28 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
#pragma once

#include <thread>
#include <mutex>
#include <queue>
#include <list>
#include <future>
#include <condition_variable>
#include <memory>
#include <atomic>

class TaskDispatcher
{
public:
	class Task
	{
	public:
		virtual void process() = 0;
		virtual ~Task() {};
	};

	typedef std::function<void(TaskDispatcher& dispatcher, std::unique_ptr<Task>)> OnTaskFinishedFunction;

	TaskDispatcher(uint32_t threadCount, OnTaskFinishedFunction onTaskFinished) :
		m_workingThreadsCount(0), m_onTaskFinished(onTaskFinished)
	{
		m_threads.resize(threadCount);
		for (uint32_t i = 0; i < threadCount; i++)
		{
			m_threads[i] = std::unique_ptr<Thread>(new Thread(i, m_completionSemaphore));
			m_threads[i]->start();
			m_freeThreads.push(m_threads[i].get());
		}
	}

	void addTask(std::unique_ptr<Task> task)
	{
		m_tasks.push(std::move(task));
	}

	void process()
	{
		// main loop
		while (m_tasks.size() > 0 || m_workingThreadsCount > 0)
		{
			// assign tasks
			while (!(m_tasks.empty() || m_freeThreads.empty()))
			{
				auto task = std::move(m_tasks.front());
				m_tasks.pop();

				Thread* freeThread = m_freeThreads.front();
				m_freeThreads.pop();

				freeThread->processTask(std::move(task));
				m_workingThreadsCount++;
			}

			m_completionSemaphore.wait();

			// check for completion
			for (std::unique_ptr<Thread>& thread : m_threads)
			{
				if (thread->isTaskFinished())
				{
					std::unique_ptr<Task> task;
					thread->collectTask(task);
					m_onTaskFinished(*this, std::move(task));

					m_freeThreads.push(thread.get());
					m_workingThreadsCount--;
					break;
				}
			}
		}
	}

private:
	class Semaphore
	{
	public:
		Semaphore(int count_ = 0)
			: m_count(count_) {}

		inline void notify()
		{
			std::unique_lock<std::mutex> lock(m_mutex);
			m_count++;
			m_cv.notify_one();
		}

		inline void wait()
		{
			std::unique_lock<std::mutex> lock(m_mutex);

			while (m_count == 0){
				m_cv.wait(lock);
			}
			m_count--;
		}


	private:
		std::mutex              m_mutex;
		std::condition_variable m_cv;
		int                     m_count;
	};

	class Thread
	{
	public:
		Thread(uint32_t id_, Semaphore& completionSemaphore) : m_id(id_), m_completionSemaphore(completionSemaphore), m_running(false), m_taskFinished(false) {}
		virtual ~Thread() { stop(); }

		void start()
		{
			if (!m_running)
			{
				m_running = true;
				m_thread = std::thread(&Thread::body, this);
			}
		}

		void stop()
		{
			if (m_running)
			{
				m_running = false;
				m_newTaskSemaphore.notify();
				m_thread.join();
			}
		}

		void processTask(std::unique_ptr<Task> task)
		{
			m_task = std::move(task);
			m_taskFinished = false;
			m_newTaskSemaphore.notify();
		}

		void collectTask(std::unique_ptr<Task>& task)
		{
			task = std::move(m_task);
			m_task = nullptr;
			m_taskFinished = false;
		}

		bool hasTask() const { return m_task != nullptr; }

		bool isTaskFinished() const { return m_taskFinished; }

	private:
		void body()
		{
			while (1)
			{
				m_newTaskSemaphore.wait();

				if (!m_running)
					return;

				m_task->process();
				m_taskFinished = true;

				m_completionSemaphore.notify();
			}
		}

		uint32_t              m_id;
		Semaphore&            m_completionSemaphore;
		std::thread           m_thread;
		bool                  m_running;

		std::unique_ptr<Task> m_task;
		std::atomic<bool>     m_taskFinished;

		Semaphore             m_newTaskSemaphore;
	};

private:
	uint32_t                             m_workingThreadsCount;

	std::queue<std::unique_ptr<Task>>    m_tasks;
	OnTaskFinishedFunction               m_onTaskFinished;

	std::vector<std::unique_ptr<Thread>> m_threads;
	std::queue<Thread*>                  m_freeThreads;

	Semaphore                            m_completionSemaphore;
};