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1 /*
2  * The copyright in this software is being made available under the 2-clauses
3  * BSD License, included below. This software may be subject to other third
4  * party and contributor rights, including patent rights, and no such rights
5  * are granted under this license.
6  *
7  * Copyright (c) 2016, Even Rouault
8  * All rights reserved.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS `AS IS'
20  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
23  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 #ifndef THREAD_H
33 #define THREAD_H
34 
35 #include "openjpeg.h"
36 
37 /**
38 @file thread.h
39 @brief Thread API
40 
41 The functions in thread.c have for goal to manage mutex, conditions, thread
42 creation and thread pools that accept jobs.
43 */
44 
45 /** @defgroup THREAD THREAD - Mutex, conditions, threads and thread pools */
46 /*@{*/
47 
48 /** @name Mutex */
49 /*@{*/
50 
51 /** Opaque type for a mutex */
52 typedef struct opj_mutex_t opj_mutex_t;
53 
54 /** Creates a mutex.
55  * @return the mutex or NULL in case of error (can for example happen if the library
56  * is built without thread support)
57  */
58 opj_mutex_t* opj_mutex_create(void);
59 
60 /** Lock/acquire the mutex.
61  * @param mutex the mutex to acquire.
62  */
63 void opj_mutex_lock(opj_mutex_t* mutex);
64 
65 /** Unlock/release the mutex.
66  * @param mutex the mutex to release.
67  */
68 void opj_mutex_unlock(opj_mutex_t* mutex);
69 
70 /** Destroy a mutex
71  * @param mutex the mutex to destroy.
72  */
73 void opj_mutex_destroy(opj_mutex_t* mutex);
74 
75 /*@}*/
76 
77 /** @name Condition */
78 /*@{*/
79 
80 /** Opaque type for a condition */
81 typedef struct opj_cond_t opj_cond_t;
82 
83 /** Creates a condition.
84  * @return the condition or NULL in case of error (can for example happen if the library
85  * is built without thread support)
86  */
87 opj_cond_t* opj_cond_create(void);
88 
89 /** Wait for the condition to be signaled.
90  * The semantics is the same as the POSIX pthread_cond_wait.
91  * The provided mutex *must* be acquired before calling this function, and
92  * released afterwards.
93  * The mutex will be released by this function while it must wait for the condition
94  * and reacquired afterwards.
95  * In some particular situations, the function might return even if the condition is not signaled
96  * with opj_cond_signal(), hence the need to check with an application level
97  * mechanism.
98  *
99  * Waiting thread :
100  * \code
101  *    opj_mutex_lock(mutex);
102  *    while( !some_application_level_condition )
103  *    {
104  *        opj_cond_wait(cond, mutex);
105  *    }
106  *    opj_mutex_unlock(mutex);
107  * \endcode
108  *
109  * Signaling thread :
110  * \code
111  *    opj_mutex_lock(mutex);
112  *    some_application_level_condition = TRUE;
113  *    opj_cond_signal(cond);
114  *    opj_mutex_unlock(mutex);
115  * \endcode
116  *
117  * @param cond the condition to wait.
118  * @param mutex the mutex (in acquired state before calling this function)
119  */
120 void opj_cond_wait(opj_cond_t* cond, opj_mutex_t* mutex);
121 
122 /** Signal waiting threads on a condition.
123  * One of the thread waiting with opj_cond_wait() will be waken up.
124  * It is strongly advised that this call is done with the mutex that is used
125  * by opj_cond_wait(), in a acquired state.
126  * @param cond the condition to signal.
127  */
128 void opj_cond_signal(opj_cond_t* cond);
129 
130 /** Destroy a condition
131  * @param cond the condition to destroy.
132  */
133 void opj_cond_destroy(opj_cond_t* cond);
134 
135 /*@}*/
136 
137 /** @name Thread */
138 /*@{*/
139 
140 /** Opaque type for a thread handle */
141 typedef struct opj_thread_t opj_thread_t;
142 
143 /** User function to execute in a thread
144  * @param user_data user data provided with opj_thread_create()
145  */
146 typedef void (*opj_thread_fn)(void* user_data);
147 
148 /** Creates a new thread.
149  * @param thread_fn Function to run in the new thread.
150  * @param user_data user data provided to the thread function. Might be NULL.
151  * @return a thread handle or NULL in case of failure (can for example happen if the library
152  * is built without thread support)
153  */
154 opj_thread_t* opj_thread_create(opj_thread_fn thread_fn, void* user_data);
155 
156 /** Wait for a thread to be finished and release associated resources to the
157  * thread handle.
158  * @param thread the thread to wait for being finished.
159  */
160 void opj_thread_join(opj_thread_t* thread);
161 
162 /*@}*/
163 
164 /** @name Thread local storage */
165 /*@{*/
166 /** Opaque type for a thread local storage */
167 typedef struct opj_tls_t opj_tls_t;
168 
169 /** Get a thread local value corresponding to the provided key.
170  * @param tls thread local storage handle
171  * @param key key whose value to retrieve.
172  * @return value associated with the key, or NULL is missing.
173  */
174 void* opj_tls_get(opj_tls_t* tls, int key);
175 
176 /** Type of the function used to free a TLS value */
177 typedef void (*opj_tls_free_func)(void* value);
178 
179 /** Set a thread local value corresponding to the provided key.
180  * @param tls thread local storage handle
181  * @param key key whose value to set.
182  * @param value value to set (may be NULL).
183  * @param free_func function to call currently installed value.
184  * @return OPJ_TRUE if successful.
185  */
186 OPJ_BOOL opj_tls_set(opj_tls_t* tls, int key, void* value,
187                      opj_tls_free_func free_func);
188 
189 /*@}*/
190 
191 /** @name Thread pool */
192 /*@{*/
193 
194 /** Opaque type for a thread pool */
195 typedef struct opj_thread_pool_t opj_thread_pool_t;
196 
197 /** Create a new thread pool.
198  * num_thread must nominally be >= 1 to create a real thread pool. If num_threads
199  * is negative or null, then a dummy thread pool will be created. All functions
200  * operating on the thread pool will work, but job submission will be run
201  * synchronously in the calling thread.
202  *
203  * @param num_threads the number of threads to allocate for this thread pool.
204  * @return a thread pool handle, or NULL in case of failure (can for example happen if the library
205  * is built without thread support)
206  */
207 opj_thread_pool_t* opj_thread_pool_create(int num_threads);
208 
209 /** User function to execute in a thread
210  * @param user_data user data provided with opj_thread_create()
211  * @param tls handle to thread local storage
212  */
213 typedef void (*opj_job_fn)(void* user_data, opj_tls_t* tls);
214 
215 
216 /** Submit a new job to be run by one of the thread in the thread pool.
217  * The job ( thread_fn, user_data ) will be added in the queue of jobs managed
218  * by the thread pool, and run by the first thread that is no longer busy.
219  *
220  * @param tp the thread pool handle.
221  * @param job_fn Function to run. Must not be NULL.
222  * @param user_data User data provided to thread_fn.
223  * @return OPJ_TRUE if the job was successfully submitted.
224  */
225 OPJ_BOOL opj_thread_pool_submit_job(opj_thread_pool_t* tp, opj_job_fn job_fn,
226                                     void* user_data);
227 
228 /** Wait that no more than max_remaining_jobs jobs are remaining in the queue of
229  * the thread pool. The aim of this function is to avoid submitting too many
230  * jobs while the thread pool cannot cope fast enough with them, which would
231  * result potentially in out-of-memory situations with too many job descriptions
232  * being queued.
233  *
234  * @param tp the thread pool handle
235  * @param max_remaining_jobs maximum number of jobs allowed to be queued without waiting.
236  */
237 void opj_thread_pool_wait_completion(opj_thread_pool_t* tp,
238                                      int max_remaining_jobs);
239 
240 /** Return the number of threads associated with the thread pool.
241  *
242  * @param tp the thread pool handle.
243  * @return number of threads associated with the thread pool.
244  */
245 int opj_thread_pool_get_thread_count(opj_thread_pool_t* tp);
246 
247 /** Destroy a thread pool.
248  * @param tp the thread pool handle.
249  */
250 void opj_thread_pool_destroy(opj_thread_pool_t* tp);
251 
252 /*@}*/
253 
254 /*@}*/
255 
256 #endif /* THREAD_H */
257