2 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
5 * This source code is licensed under both the BSD-style license (found in the
6 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
7 * in the COPYING file in the root directory of this source tree).
8 * You may select, at your option, one of the above-listed licenses.
12 /* ====== Dependencies ======= */
13 #include <stddef.h> /* size_t */
14 #include <stdlib.h> /* malloc, calloc, free */
17 /* ====== Compiler specifics ====== */
19 # pragma warning(disable : 4204) /* disable: C4204: non-constant aggregate initializer */
23 #ifdef ZSTD_MULTITHREAD
25 #include "threading.h" /* pthread adaptation */
27 /* A job is a function and an opaque argument */
28 typedef struct POOL_job_s {
29 POOL_function function;
34 ZSTD_customMem customMem;
35 /* Keep track of the threads */
36 ZSTD_pthread_t *threads;
39 /* The queue is a circular buffer */
45 /* The number of threads working on jobs */
46 size_t numThreadsBusy;
47 /* Indicates if the queue is empty */
50 /* The mutex protects the queue */
51 ZSTD_pthread_mutex_t queueMutex;
52 /* Condition variable for pushers to wait on when the queue is full */
53 ZSTD_pthread_cond_t queuePushCond;
54 /* Condition variables for poppers to wait on when the queue is empty */
55 ZSTD_pthread_cond_t queuePopCond;
56 /* Indicates if the queue is shutting down */
61 Work thread for the thread pool.
62 Waits for jobs and executes them.
63 @returns : NULL on failure else non-null.
65 static void* POOL_thread(void* opaque) {
66 POOL_ctx* const ctx = (POOL_ctx*)opaque;
67 if (!ctx) { return NULL; }
69 /* Lock the mutex and wait for a non-empty queue or until shutdown */
70 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
72 while (ctx->queueEmpty && !ctx->shutdown) {
73 ZSTD_pthread_cond_wait(&ctx->queuePopCond, &ctx->queueMutex);
75 /* empty => shutting down: so stop */
76 if (ctx->queueEmpty) {
77 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
80 /* Pop a job off the queue */
81 { POOL_job const job = ctx->queue[ctx->queueHead];
82 ctx->queueHead = (ctx->queueHead + 1) % ctx->queueSize;
83 ctx->numThreadsBusy++;
84 ctx->queueEmpty = ctx->queueHead == ctx->queueTail;
85 /* Unlock the mutex, signal a pusher, and run the job */
86 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
87 ZSTD_pthread_cond_signal(&ctx->queuePushCond);
89 job.function(job.opaque);
91 /* If the intended queue size was 0, signal after finishing job */
92 if (ctx->queueSize == 1) {
93 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
94 ctx->numThreadsBusy--;
95 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
96 ZSTD_pthread_cond_signal(&ctx->queuePushCond);
102 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
103 return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
106 POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize, ZSTD_customMem customMem) {
108 /* Check the parameters */
109 if (!numThreads) { return NULL; }
110 /* Allocate the context and zero initialize */
111 ctx = (POOL_ctx*)ZSTD_calloc(sizeof(POOL_ctx), customMem);
112 if (!ctx) { return NULL; }
113 /* Initialize the job queue.
114 * It needs one extra space since one space is wasted to differentiate empty
117 ctx->queueSize = queueSize + 1;
118 ctx->queue = (POOL_job*) malloc(ctx->queueSize * sizeof(POOL_job));
121 ctx->numThreadsBusy = 0;
123 (void)ZSTD_pthread_mutex_init(&ctx->queueMutex, NULL);
124 (void)ZSTD_pthread_cond_init(&ctx->queuePushCond, NULL);
125 (void)ZSTD_pthread_cond_init(&ctx->queuePopCond, NULL);
127 /* Allocate space for the thread handles */
128 ctx->threads = (ZSTD_pthread_t*)ZSTD_malloc(numThreads * sizeof(ZSTD_pthread_t), customMem);
130 ctx->customMem = customMem;
131 /* Check for errors */
132 if (!ctx->threads || !ctx->queue) { POOL_free(ctx); return NULL; }
133 /* Initialize the threads */
135 for (i = 0; i < numThreads; ++i) {
136 if (ZSTD_pthread_create(&ctx->threads[i], NULL, &POOL_thread, ctx)) {
141 ctx->numThreads = numThreads;
147 Shutdown the queue, wake any sleeping threads, and join all of the threads.
149 static void POOL_join(POOL_ctx* ctx) {
150 /* Shut down the queue */
151 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
153 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
154 /* Wake up sleeping threads */
155 ZSTD_pthread_cond_broadcast(&ctx->queuePushCond);
156 ZSTD_pthread_cond_broadcast(&ctx->queuePopCond);
157 /* Join all of the threads */
159 for (i = 0; i < ctx->numThreads; ++i) {
160 ZSTD_pthread_join(ctx->threads[i], NULL);
164 void POOL_free(POOL_ctx *ctx) {
165 if (!ctx) { return; }
167 ZSTD_pthread_mutex_destroy(&ctx->queueMutex);
168 ZSTD_pthread_cond_destroy(&ctx->queuePushCond);
169 ZSTD_pthread_cond_destroy(&ctx->queuePopCond);
170 ZSTD_free(ctx->queue, ctx->customMem);
171 ZSTD_free(ctx->threads, ctx->customMem);
172 ZSTD_free(ctx, ctx->customMem);
175 size_t POOL_sizeof(POOL_ctx *ctx) {
176 if (ctx==NULL) return 0; /* supports sizeof NULL */
178 + ctx->queueSize * sizeof(POOL_job)
179 + ctx->numThreads * sizeof(ZSTD_pthread_t);
183 * Returns 1 if the queue is full and 0 otherwise.
185 * If the queueSize is 1 (the pool was created with an intended queueSize of 0),
186 * then a queue is empty if there is a thread free and no job is waiting.
188 static int isQueueFull(POOL_ctx const* ctx) {
189 if (ctx->queueSize > 1) {
190 return ctx->queueHead == ((ctx->queueTail + 1) % ctx->queueSize);
192 return ctx->numThreadsBusy == ctx->numThreads ||
197 void POOL_add(void* ctxVoid, POOL_function function, void *opaque) {
198 POOL_ctx* const ctx = (POOL_ctx*)ctxVoid;
199 if (!ctx) { return; }
201 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
202 { POOL_job const job = {function, opaque};
204 /* Wait until there is space in the queue for the new job */
205 while (isQueueFull(ctx) && !ctx->shutdown) {
206 ZSTD_pthread_cond_wait(&ctx->queuePushCond, &ctx->queueMutex);
208 /* The queue is still going => there is space */
209 if (!ctx->shutdown) {
211 ctx->queue[ctx->queueTail] = job;
212 ctx->queueTail = (ctx->queueTail + 1) % ctx->queueSize;
215 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
216 ZSTD_pthread_cond_signal(&ctx->queuePopCond);
219 #else /* ZSTD_MULTITHREAD not defined */
220 /* No multi-threading support */
222 /* We don't need any data, but if it is empty malloc() might return NULL. */
226 static POOL_ctx g_ctx;
228 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
229 return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
232 POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize, ZSTD_customMem customMem) {
239 void POOL_free(POOL_ctx* ctx) {
240 assert(!ctx || ctx == &g_ctx);
244 void POOL_add(void* ctx, POOL_function function, void* opaque) {
249 size_t POOL_sizeof(POOL_ctx* ctx) {
250 if (ctx==NULL) return 0; /* supports sizeof NULL */
251 assert(ctx == &g_ctx);
255 #endif /* ZSTD_MULTITHREAD */