1/*
2 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
3 * All rights reserved.
4 *
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.
9 */
10
11
12/* ====== Dependencies ======= */
13#include <stddef.h> /* size_t */
14#include "pool.h"
15#include "zstd_internal.h" /* ZSTD_malloc, ZSTD_free */
16
17/* ====== Compiler specifics ====== */
18#if defined(_MSC_VER)
19# pragma warning(disable : 4204) /* disable: C4204: non-constant aggregate initializer */
20#endif
21
22
23#ifdef ZSTD_MULTITHREAD
24
25#include "threading.h" /* pthread adaptation */
26
27/* A job is a function and an opaque argument */
28typedef struct POOL_job_s {
29 POOL_function function;
30 void *opaque;
31} POOL_job;
32
33struct POOL_ctx_s {
34 ZSTD_customMem customMem;
35 /* Keep track of the threads */
36 ZSTD_pthread_t *threads;
37 size_t numThreads;
38
39 /* The queue is a circular buffer */
40 POOL_job *queue;
41 size_t queueHead;
42 size_t queueTail;
43 size_t queueSize;
44
45 /* The number of threads working on jobs */
46 size_t numThreadsBusy;
47 /* Indicates if the queue is empty */
48 int queueEmpty;
49
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 */
57 int shutdown;
58};
59
60/* POOL_thread() :
61 Work thread for the thread pool.
62 Waits for jobs and executes them.
63 @returns : NULL on failure else non-null.
64*/
65static void* POOL_thread(void* opaque) {
66 POOL_ctx* const ctx = (POOL_ctx*)opaque;
67 if (!ctx) { return NULL; }
68 for (;;) {
69 /* Lock the mutex and wait for a non-empty queue or until shutdown */
70 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
71
72 while (ctx->queueEmpty && !ctx->shutdown) {
73 ZSTD_pthread_cond_wait(&ctx->queuePopCond, &ctx->queueMutex);
74 }
75 /* empty => shutting down: so stop */
76 if (ctx->queueEmpty) {
77 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
78 return opaque;
79 }
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);
88
89 job.function(job.opaque);
90
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);
97 } }
98 } /* for (;;) */
99 /* Unreachable */
100}
101
102POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
103 return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
104}
105
106POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize, ZSTD_customMem customMem) {
107 POOL_ctx* ctx;
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
115 * and full queues.
116 */
117 ctx->queueSize = queueSize + 1;
118 ctx->queue = (POOL_job*)ZSTD_malloc(ctx->queueSize * sizeof(POOL_job), customMem);
119 ctx->queueHead = 0;
120 ctx->queueTail = 0;
121 ctx->numThreadsBusy = 0;
122 ctx->queueEmpty = 1;
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);
126 ctx->shutdown = 0;
127 /* Allocate space for the thread handles */
128 ctx->threads = (ZSTD_pthread_t*)ZSTD_malloc(numThreads * sizeof(ZSTD_pthread_t), customMem);
129 ctx->numThreads = 0;
130 ctx->customMem = customMem;
131 /* Check for errors */
132 if (!ctx->threads || !ctx->queue) { POOL_free(ctx); return NULL; }
133 /* Initialize the threads */
134 { size_t i;
135 for (i = 0; i < numThreads; ++i) {
136 if (ZSTD_pthread_create(&ctx->threads[i], NULL, &POOL_thread, ctx)) {
137 ctx->numThreads = i;
138 POOL_free(ctx);
139 return NULL;
140 } }
141 ctx->numThreads = numThreads;
142 }
143 return ctx;
144}
145
146/*! POOL_join() :
147 Shutdown the queue, wake any sleeping threads, and join all of the threads.
148*/
149static void POOL_join(POOL_ctx* ctx) {
150 /* Shut down the queue */
151 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
152 ctx->shutdown = 1;
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 */
158 { size_t i;
159 for (i = 0; i < ctx->numThreads; ++i) {
160 ZSTD_pthread_join(ctx->threads[i], NULL);
161 } }
162}
163
164void POOL_free(POOL_ctx *ctx) {
165 if (!ctx) { return; }
166 POOL_join(ctx);
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);
173}
174
175size_t POOL_sizeof(POOL_ctx *ctx) {
176 if (ctx==NULL) return 0; /* supports sizeof NULL */
177 return sizeof(*ctx)
178 + ctx->queueSize * sizeof(POOL_job)
179 + ctx->numThreads * sizeof(ZSTD_pthread_t);
180}
181
182/**
183 * Returns 1 if the queue is full and 0 otherwise.
184 *
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.
187 */
188static int isQueueFull(POOL_ctx const* ctx) {
189 if (ctx->queueSize > 1) {
190 return ctx->queueHead == ((ctx->queueTail + 1) % ctx->queueSize);
191 } else {
192 return ctx->numThreadsBusy == ctx->numThreads ||
193 !ctx->queueEmpty;
194 }
195}
196
197
198static void POOL_add_internal(POOL_ctx* ctx, POOL_function function, void *opaque)
199{
200 POOL_job const job = {function, opaque};
201 assert(ctx != NULL);
202 if (ctx->shutdown) return;
203
204 ctx->queueEmpty = 0;
205 ctx->queue[ctx->queueTail] = job;
206 ctx->queueTail = (ctx->queueTail + 1) % ctx->queueSize;
207 ZSTD_pthread_cond_signal(&ctx->queuePopCond);
208}
209
210void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque)
211{
212 assert(ctx != NULL);
213 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
214 /* Wait until there is space in the queue for the new job */
215 while (isQueueFull(ctx) && (!ctx->shutdown)) {
216 ZSTD_pthread_cond_wait(&ctx->queuePushCond, &ctx->queueMutex);
217 }
218 POOL_add_internal(ctx, function, opaque);
219 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
220}
221
222
223int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque)
224{
225 assert(ctx != NULL);
226 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
227 if (isQueueFull(ctx)) {
228 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
229 return 0;
230 }
231 POOL_add_internal(ctx, function, opaque);
232 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
233 return 1;
234}
235
236
237#else /* ZSTD_MULTITHREAD not defined */
238
239/* ========================== */
240/* No multi-threading support */
241/* ========================== */
242
243
244/* We don't need any data, but if it is empty, malloc() might return NULL. */
245struct POOL_ctx_s {
246 int dummy;
247};
248static POOL_ctx g_ctx;
249
250POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
251 return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
252}
253
254POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize, ZSTD_customMem customMem) {
255 (void)numThreads;
256 (void)queueSize;
257 (void)customMem;
258 return &g_ctx;
259}
260
261void POOL_free(POOL_ctx* ctx) {
262 assert(!ctx || ctx == &g_ctx);
263 (void)ctx;
264}
265
266void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque) {
267 (void)ctx;
268 function(opaque);
269}
270
271int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque) {
272 (void)ctx;
273 function(opaque);
274 return 1;
275}
276
277size_t POOL_sizeof(POOL_ctx* ctx) {
278 if (ctx==NULL) return 0; /* supports sizeof NULL */
279 assert(ctx == &g_ctx);
280 return sizeof(*ctx);
281}
282
283#endif /* ZSTD_MULTITHREAD */
284