dlib.concurrency.taskqueue 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.taskqueue;
35 
36 import dlib.core.mutex;
37 import dlib.container.array;
38 import dlib.concurrency.workerthread;
39 
40 /**
41  * State of a Task
42  */
43 enum TaskState
44 {
45     Valid = 0,
46     Invalid = 1
47 }
48 
49 /**
50  * Task object that encapsulates a delegate
51  */
52 struct Task
53 {
54     TaskState state = TaskState.Invalid;
55     void delegate() func;
56 
57     void run()
58     {
59         if (func !is null)
60         {
61             func();
62         }
63     }
64 }
65 
66 /**
67  * Asynchronous task queue
68  */
69 class TaskQueue
70 {
71     protected:
72     enum size_t MaxTasks = 64;
73     Array!(Task, MaxTasks) tasks;
74     Mutex mutex;
75 
76     public:
77     
78     /// Constructor
79     this()
80     {
81         mutex.init();
82     }
83 
84     ~this()
85     {
86         tasks.free();
87         mutex.destroy();
88     }
89 
90     /// Number of queued tasks
91     size_t count()
92     {
93         return tasks.length;
94     }
95 
96     /// Add a task to queue
97     bool enqueue(Task task)
98     {
99         if (tasks.length < MaxTasks)
100         {
101             mutex.lock();
102             tasks.insertFront(task);
103             mutex.unlock();
104             return true;
105         }
106         else
107             return false;
108     }
109 
110     /// Remove a task from queue
111     Task dequeue()
112     {
113         if (tasks.length)
114         {
115             mutex.lock();
116             Task t = tasks[tasks.length-1];
117             tasks.removeBack(1);
118             mutex.unlock();
119             return t;
120         }
121         else
122             return Task(TaskState.Invalid, null);
123     }
124 }