dlib.concurrency.threadpool source code

1 /*
2 Copyright (c) 2019-2021 Timur Gafarov
3 
4 Boost Software License - Version 1.0 - August 17th, 2003
5 
6 Permission is hereby granted, free of charge, to any person or organization
7 obtaining a copy of the software and accompanying documentation covered by
8 this license (the "Software") to use, reproduce, display, distribute,
9 execute, and transmit the Software, and to prepare derivative works of the
10 Software, and to permit third-parties to whom the Software is furnished to
11 do so, all subject to the following:
12 
13 The copyright notices in the Software and this entire statement, including
14 the above license grant, this restriction and the following disclaimer,
15 must be included in all copies of the Software, in whole or in part, and
16 all derivative works of the Software, unless such copies or derivative
17 works are solely in the form of machine-executable object code generated by
18 a source language processor.
19 
20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
23 SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
24 FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
25 ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
26 DEALINGS IN THE SOFTWARE.
27 */
28 
29 /**
30  * Copyright: Timur Gafarov 2019-2021.
31  * License: $(LINK2 boost.org/LICENSE_1_0.txt, Boost License 1.0).
32  * Authors: Timur Gafarov
33  */
34 module dlib.concurrency.threadpool;
35 
36 import std.functional;
37 import dlib.core.memory;
38 import dlib.core.mutex;
39 import dlib.concurrency.workerthread;
40 import dlib.concurrency.taskqueue;
41 
42 /**
43  * An object that manages worker threads and runs tasks on them
44  */
45 class ThreadPool
46 {
47     protected:
48     uint maxThreads;
49     WorkerThread[] workerThreads;
50     TaskQueue taskQueue;
51     bool running = true;
52     Mutex mutex;
53 
54     public:
55     
56     /// Constructor
57     this(uint maxThreads)
58     {
59         this.maxThreads = maxThreads;
60         workerThreads = New!(WorkerThread[])(maxThreads);
61         taskQueue = New!TaskQueue();
62 
63         mutex.init();
64 
65         foreach(i, ref t; workerThreads)
66         {
67             t = New!WorkerThread(i, this);
68             t.start();
69         }
70     }
71 
72     ~this()
73     {
74         mutex.lock();
75         running = false;
76         mutex.unlock();
77 
78         foreach(i, ref t; workerThreads)
79         {
80             t.join();
81             Delete(t);
82         }
83 
84         Delete(taskQueue);
85         Delete(workerThreads);
86 
87         mutex.destroy();
88     }
89 
90     /// Create a task from delegate
91     Task submit(void delegate() taskDele)
92     {
93         Task task = Task(TaskState.Valid, taskDele);
94         if (!taskQueue.enqueue(task))
95         {
96             task.run();
97         }
98         return task;
99     }
100 
101     /// Create a task from function pointer
102     Task submit(void function() taskFunc)
103     {
104         return submit(toDelegate(taskFunc));
105     }
106 
107     Task request()
108     {
109         return taskQueue.dequeue();
110     }
111 
112     bool isRunning()
113     {
114         return running;
115     }
116 
117     /// Returns true if all tasks are finished
118     bool tasksDone()
119     {
120         if (taskQueue.count == 0)
121         {
122             foreach(i, t; workerThreads)
123             {
124                 if (t.busy)
125                     return false;
126             }
127 
128             return true;
129         }
130         else
131             return false;
132     }
133 }
134 
135 ///
136 unittest
137 {
138     import std.stdio;
139 
140     int x = 0;
141     int y = 0;
142 
143     void task1()
144     {
145         while(x < 100)
146             x += 1;
147     }
148 
149     void task2()
150     {
151         while(y < 100)
152             y += 1;
153     }
154 
155     ThreadPool threadPool = New!ThreadPool(2);
156 
157     threadPool.submit(&task1);
158     threadPool.submit(&task2);
159 
160     while(!threadPool.tasksDone) {}
161 
162     if (x != 100) writeln(x);
163     if (y != 100) writeln(y);
164 
165     assert(x == 100);
166     assert(y == 100);
167 
168     Delete(threadPool);
169 }