1 /*
2 * Copyright (c) 2016-2020, 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 "zstd_deps.h" /* size_t */
14 #include "debug.h" /* assert */
15 #include "zstd_internal.h" /* ZSTD_customMalloc, ZSTD_customFree */
16 #include "pool.h"
17
18 /* ====== Compiler specifics ====== */
19 #if defined(_MSC_VER)
20 # pragma warning(disable : 4204) /* disable: C4204: non-constant aggregate initializer */
21 #endif
22
23
24 #ifdef ZSTD_MULTITHREAD
25
26 #include "threading.h" /* pthread adaptation */
27
28 /* A job is a function and an opaque argument */
29 typedef struct POOL_job_s {
30 POOL_function function;
31 void *opaque;
32 } POOL_job;
33
34 struct POOL_ctx_s {
35 ZSTD_customMem customMem;
36 /* Keep track of the threads */
37 ZSTD_pthread_t* threads;
38 size_t threadCapacity;
39 size_t threadLimit;
40
41 /* The queue is a circular buffer */
42 POOL_job *queue;
43 size_t queueHead;
44 size_t queueTail;
45 size_t queueSize;
46
47 /* The number of threads working on jobs */
48 size_t numThreadsBusy;
49 /* Indicates if the queue is empty */
50 int queueEmpty;
51
52 /* The mutex protects the queue */
53 ZSTD_pthread_mutex_t queueMutex;
54 /* Condition variable for pushers to wait on when the queue is full */
55 ZSTD_pthread_cond_t queuePushCond;
56 /* Condition variables for poppers to wait on when the queue is empty */
57 ZSTD_pthread_cond_t queuePopCond;
58 /* Indicates if the queue is shutting down */
59 int shutdown;
60 };
61
62 /* POOL_thread() :
63 * Work thread for the thread pool.
64 * Waits for jobs and executes them.
65 * @returns : NULL on failure else non-null.
66 */
POOL_thread(void * opaque)67 static void* POOL_thread(void* opaque) {
68 POOL_ctx* const ctx = (POOL_ctx*)opaque;
69 if (!ctx) { return NULL; }
70 for (;;) {
71 /* Lock the mutex and wait for a non-empty queue or until shutdown */
72 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
73
74 while ( ctx->queueEmpty
75 || (ctx->numThreadsBusy >= ctx->threadLimit) ) {
76 if (ctx->shutdown) {
77 /* even if !queueEmpty, (possible if numThreadsBusy >= threadLimit),
78 * a few threads will be shutdown while !queueEmpty,
79 * but enough threads will remain active to finish the queue */
80 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
81 return opaque;
82 }
83 ZSTD_pthread_cond_wait(&ctx->queuePopCond, &ctx->queueMutex);
84 }
85 /* Pop a job off the queue */
86 { POOL_job const job = ctx->queue[ctx->queueHead];
87 ctx->queueHead = (ctx->queueHead + 1) % ctx->queueSize;
88 ctx->numThreadsBusy++;
89 ctx->queueEmpty = ctx->queueHead == ctx->queueTail;
90 /* Unlock the mutex, signal a pusher, and run the job */
91 ZSTD_pthread_cond_signal(&ctx->queuePushCond);
92 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
93
94 job.function(job.opaque);
95
96 /* If the intended queue size was 0, signal after finishing job */
97 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
98 ctx->numThreadsBusy--;
99 if (ctx->queueSize == 1) {
100 ZSTD_pthread_cond_signal(&ctx->queuePushCond);
101 }
102 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
103 }
104 } /* for (;;) */
105 assert(0); /* Unreachable */
106 }
107
ZSTD_createThreadPool(size_t numThreads)108 POOL_ctx* ZSTD_createThreadPool(size_t numThreads) {
109 return POOL_create (numThreads, 0);
110 }
111
POOL_create(size_t numThreads,size_t queueSize)112 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
113 return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
114 }
115
POOL_create_advanced(size_t numThreads,size_t queueSize,ZSTD_customMem customMem)116 POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize,
117 ZSTD_customMem customMem) {
118 POOL_ctx* ctx;
119 /* Check parameters */
120 if (!numThreads) { return NULL; }
121 /* Allocate the context and zero initialize */
122 ctx = (POOL_ctx*)ZSTD_customCalloc(sizeof(POOL_ctx), customMem);
123 if (!ctx) { return NULL; }
124 /* Initialize the job queue.
125 * It needs one extra space since one space is wasted to differentiate
126 * empty and full queues.
127 */
128 ctx->queueSize = queueSize + 1;
129 ctx->queue = (POOL_job*)ZSTD_customMalloc(ctx->queueSize * sizeof(POOL_job), customMem);
130 ctx->queueHead = 0;
131 ctx->queueTail = 0;
132 ctx->numThreadsBusy = 0;
133 ctx->queueEmpty = 1;
134 {
135 int error = 0;
136 error |= ZSTD_pthread_mutex_init(&ctx->queueMutex, NULL);
137 error |= ZSTD_pthread_cond_init(&ctx->queuePushCond, NULL);
138 error |= ZSTD_pthread_cond_init(&ctx->queuePopCond, NULL);
139 if (error) { POOL_free(ctx); return NULL; }
140 }
141 ctx->shutdown = 0;
142 /* Allocate space for the thread handles */
143 ctx->threads = (ZSTD_pthread_t*)ZSTD_customMalloc(numThreads * sizeof(ZSTD_pthread_t), customMem);
144 ctx->threadCapacity = 0;
145 ctx->customMem = customMem;
146 /* Check for errors */
147 if (!ctx->threads || !ctx->queue) { POOL_free(ctx); return NULL; }
148 /* Initialize the threads */
149 { size_t i;
150 for (i = 0; i < numThreads; ++i) {
151 if (ZSTD_pthread_create(&ctx->threads[i], NULL, &POOL_thread, ctx)) {
152 ctx->threadCapacity = i;
153 POOL_free(ctx);
154 return NULL;
155 } }
156 ctx->threadCapacity = numThreads;
157 ctx->threadLimit = numThreads;
158 }
159 return ctx;
160 }
161
162 /*! POOL_join() :
163 Shutdown the queue, wake any sleeping threads, and join all of the threads.
164 */
POOL_join(POOL_ctx * ctx)165 static void POOL_join(POOL_ctx* ctx) {
166 /* Shut down the queue */
167 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
168 ctx->shutdown = 1;
169 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
170 /* Wake up sleeping threads */
171 ZSTD_pthread_cond_broadcast(&ctx->queuePushCond);
172 ZSTD_pthread_cond_broadcast(&ctx->queuePopCond);
173 /* Join all of the threads */
174 { size_t i;
175 for (i = 0; i < ctx->threadCapacity; ++i) {
176 ZSTD_pthread_join(ctx->threads[i], NULL); /* note : could fail */
177 } }
178 }
179
POOL_free(POOL_ctx * ctx)180 void POOL_free(POOL_ctx *ctx) {
181 if (!ctx) { return; }
182 POOL_join(ctx);
183 ZSTD_pthread_mutex_destroy(&ctx->queueMutex);
184 ZSTD_pthread_cond_destroy(&ctx->queuePushCond);
185 ZSTD_pthread_cond_destroy(&ctx->queuePopCond);
186 ZSTD_customFree(ctx->queue, ctx->customMem);
187 ZSTD_customFree(ctx->threads, ctx->customMem);
188 ZSTD_customFree(ctx, ctx->customMem);
189 }
190
ZSTD_freeThreadPool(ZSTD_threadPool * pool)191 void ZSTD_freeThreadPool (ZSTD_threadPool* pool) {
192 POOL_free (pool);
193 }
194
POOL_sizeof(POOL_ctx * ctx)195 size_t POOL_sizeof(POOL_ctx *ctx) {
196 if (ctx==NULL) return 0; /* supports sizeof NULL */
197 return sizeof(*ctx)
198 + ctx->queueSize * sizeof(POOL_job)
199 + ctx->threadCapacity * sizeof(ZSTD_pthread_t);
200 }
201
202
203 /* @return : 0 on success, 1 on error */
POOL_resize_internal(POOL_ctx * ctx,size_t numThreads)204 static int POOL_resize_internal(POOL_ctx* ctx, size_t numThreads)
205 {
206 if (numThreads <= ctx->threadCapacity) {
207 if (!numThreads) return 1;
208 ctx->threadLimit = numThreads;
209 return 0;
210 }
211 /* numThreads > threadCapacity */
212 { ZSTD_pthread_t* const threadPool = (ZSTD_pthread_t*)ZSTD_customMalloc(numThreads * sizeof(ZSTD_pthread_t), ctx->customMem);
213 if (!threadPool) return 1;
214 /* replace existing thread pool */
215 ZSTD_memcpy(threadPool, ctx->threads, ctx->threadCapacity * sizeof(*threadPool));
216 ZSTD_customFree(ctx->threads, ctx->customMem);
217 ctx->threads = threadPool;
218 /* Initialize additional threads */
219 { size_t threadId;
220 for (threadId = ctx->threadCapacity; threadId < numThreads; ++threadId) {
221 if (ZSTD_pthread_create(&threadPool[threadId], NULL, &POOL_thread, ctx)) {
222 ctx->threadCapacity = threadId;
223 return 1;
224 } }
225 } }
226 /* successfully expanded */
227 ctx->threadCapacity = numThreads;
228 ctx->threadLimit = numThreads;
229 return 0;
230 }
231
232 /* @return : 0 on success, 1 on error */
POOL_resize(POOL_ctx * ctx,size_t numThreads)233 int POOL_resize(POOL_ctx* ctx, size_t numThreads)
234 {
235 int result;
236 if (ctx==NULL) return 1;
237 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
238 result = POOL_resize_internal(ctx, numThreads);
239 ZSTD_pthread_cond_broadcast(&ctx->queuePopCond);
240 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
241 return result;
242 }
243
244 /**
245 * Returns 1 if the queue is full and 0 otherwise.
246 *
247 * When queueSize is 1 (pool was created with an intended queueSize of 0),
248 * then a queue is empty if there is a thread free _and_ no job is waiting.
249 */
isQueueFull(POOL_ctx const * ctx)250 static int isQueueFull(POOL_ctx const* ctx) {
251 if (ctx->queueSize > 1) {
252 return ctx->queueHead == ((ctx->queueTail + 1) % ctx->queueSize);
253 } else {
254 return (ctx->numThreadsBusy == ctx->threadLimit) ||
255 !ctx->queueEmpty;
256 }
257 }
258
259
POOL_add_internal(POOL_ctx * ctx,POOL_function function,void * opaque)260 static void POOL_add_internal(POOL_ctx* ctx, POOL_function function, void *opaque)
261 {
262 POOL_job const job = {function, opaque};
263 assert(ctx != NULL);
264 if (ctx->shutdown) return;
265
266 ctx->queueEmpty = 0;
267 ctx->queue[ctx->queueTail] = job;
268 ctx->queueTail = (ctx->queueTail + 1) % ctx->queueSize;
269 ZSTD_pthread_cond_signal(&ctx->queuePopCond);
270 }
271
POOL_add(POOL_ctx * ctx,POOL_function function,void * opaque)272 void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque)
273 {
274 assert(ctx != NULL);
275 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
276 /* Wait until there is space in the queue for the new job */
277 while (isQueueFull(ctx) && (!ctx->shutdown)) {
278 ZSTD_pthread_cond_wait(&ctx->queuePushCond, &ctx->queueMutex);
279 }
280 POOL_add_internal(ctx, function, opaque);
281 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
282 }
283
284
POOL_tryAdd(POOL_ctx * ctx,POOL_function function,void * opaque)285 int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque)
286 {
287 assert(ctx != NULL);
288 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
289 if (isQueueFull(ctx)) {
290 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
291 return 0;
292 }
293 POOL_add_internal(ctx, function, opaque);
294 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
295 return 1;
296 }
297
298
299 #else /* ZSTD_MULTITHREAD not defined */
300
301 /* ========================== */
302 /* No multi-threading support */
303 /* ========================== */
304
305
306 /* We don't need any data, but if it is empty, malloc() might return NULL. */
307 struct POOL_ctx_s {
308 int dummy;
309 };
310 static POOL_ctx g_poolCtx;
311
POOL_create(size_t numThreads,size_t queueSize)312 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
313 return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
314 }
315
POOL_create_advanced(size_t numThreads,size_t queueSize,ZSTD_customMem customMem)316 POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize, ZSTD_customMem customMem) {
317 (void)numThreads;
318 (void)queueSize;
319 (void)customMem;
320 return &g_poolCtx;
321 }
322
POOL_free(POOL_ctx * ctx)323 void POOL_free(POOL_ctx* ctx) {
324 assert(!ctx || ctx == &g_poolCtx);
325 (void)ctx;
326 }
327
POOL_resize(POOL_ctx * ctx,size_t numThreads)328 int POOL_resize(POOL_ctx* ctx, size_t numThreads) {
329 (void)ctx; (void)numThreads;
330 return 0;
331 }
332
POOL_add(POOL_ctx * ctx,POOL_function function,void * opaque)333 void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque) {
334 (void)ctx;
335 function(opaque);
336 }
337
POOL_tryAdd(POOL_ctx * ctx,POOL_function function,void * opaque)338 int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque) {
339 (void)ctx;
340 function(opaque);
341 return 1;
342 }
343
POOL_sizeof(POOL_ctx * ctx)344 size_t POOL_sizeof(POOL_ctx* ctx) {
345 if (ctx==NULL) return 0; /* supports sizeof NULL */
346 assert(ctx == &g_poolCtx);
347 return sizeof(*ctx);
348 }
349
350 #endif /* ZSTD_MULTITHREAD */
351