1 // SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0-only
2 /*
3 * Copyright (c) Meta Platforms, Inc. and affiliates.
4 * All rights reserved.
5 *
6 * This source code is licensed under both the BSD-style license (found in the
7 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
8 * in the COPYING file in the root directory of this source tree).
9 * You may select, at your option, one of the above-listed licenses.
10 */
11
12
13 /* ====== Dependencies ======= */
14 #include "../common/allocations.h" /* ZSTD_customCalloc, ZSTD_customFree */
15 #include "zstd_deps.h" /* size_t */
16 #include "debug.h" /* assert */
17 #include "pool.h"
18
19 /* ====== Compiler specifics ====== */
20 #if defined(_MSC_VER)
21 # pragma warning(disable : 4204) /* disable: C4204: non-constant aggregate initializer */
22 #endif
23
24
25 #ifdef ZSTD_MULTITHREAD
26
27 #include "threading.h" /* pthread adaptation */
28
29 /* A job is a function and an opaque argument */
30 typedef struct POOL_job_s {
31 POOL_function function;
32 void *opaque;
33 } POOL_job;
34
35 struct POOL_ctx_s {
36 ZSTD_customMem customMem;
37 /* Keep track of the threads */
38 ZSTD_pthread_t* threads;
39 size_t threadCapacity;
40 size_t threadLimit;
41
42 /* The queue is a circular buffer */
43 POOL_job *queue;
44 size_t queueHead;
45 size_t queueTail;
46 size_t queueSize;
47
48 /* The number of threads working on jobs */
49 size_t numThreadsBusy;
50 /* Indicates if the queue is empty */
51 int queueEmpty;
52
53 /* The mutex protects the queue */
54 ZSTD_pthread_mutex_t queueMutex;
55 /* Condition variable for pushers to wait on when the queue is full */
56 ZSTD_pthread_cond_t queuePushCond;
57 /* Condition variables for poppers to wait on when the queue is empty */
58 ZSTD_pthread_cond_t queuePopCond;
59 /* Indicates if the queue is shutting down */
60 int shutdown;
61 };
62
63 /* POOL_thread() :
64 * Work thread for the thread pool.
65 * Waits for jobs and executes them.
66 * @returns : NULL on failure else non-null.
67 */
POOL_thread(void * opaque)68 static void* POOL_thread(void* opaque) {
69 POOL_ctx* const ctx = (POOL_ctx*)opaque;
70 if (!ctx) { return NULL; }
71 for (;;) {
72 /* Lock the mutex and wait for a non-empty queue or until shutdown */
73 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
74
75 while ( ctx->queueEmpty
76 || (ctx->numThreadsBusy >= ctx->threadLimit) ) {
77 if (ctx->shutdown) {
78 /* even if !queueEmpty, (possible if numThreadsBusy >= threadLimit),
79 * a few threads will be shutdown while !queueEmpty,
80 * but enough threads will remain active to finish the queue */
81 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
82 return opaque;
83 }
84 ZSTD_pthread_cond_wait(&ctx->queuePopCond, &ctx->queueMutex);
85 }
86 /* Pop a job off the queue */
87 { POOL_job const job = ctx->queue[ctx->queueHead];
88 ctx->queueHead = (ctx->queueHead + 1) % ctx->queueSize;
89 ctx->numThreadsBusy++;
90 ctx->queueEmpty = (ctx->queueHead == ctx->queueTail);
91 /* Unlock the mutex, signal a pusher, and run the job */
92 ZSTD_pthread_cond_signal(&ctx->queuePushCond);
93 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
94
95 job.function(job.opaque);
96
97 /* If the intended queue size was 0, signal after finishing job */
98 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
99 ctx->numThreadsBusy--;
100 ZSTD_pthread_cond_signal(&ctx->queuePushCond);
101 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
102 }
103 } /* for (;;) */
104 assert(0); /* Unreachable */
105 }
106
107 /* ZSTD_createThreadPool() : public access point */
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 {
119 POOL_ctx* ctx;
120 /* Check parameters */
121 if (!numThreads) { return NULL; }
122 /* Allocate the context and zero initialize */
123 ctx = (POOL_ctx*)ZSTD_customCalloc(sizeof(POOL_ctx), customMem);
124 if (!ctx) { return NULL; }
125 /* Initialize the job queue.
126 * It needs one extra space since one space is wasted to differentiate
127 * empty and full queues.
128 */
129 ctx->queueSize = queueSize + 1;
130 ctx->queue = (POOL_job*)ZSTD_customCalloc(ctx->queueSize * sizeof(POOL_job), customMem);
131 ctx->queueHead = 0;
132 ctx->queueTail = 0;
133 ctx->numThreadsBusy = 0;
134 ctx->queueEmpty = 1;
135 {
136 int error = 0;
137 error |= ZSTD_pthread_mutex_init(&ctx->queueMutex, NULL);
138 error |= ZSTD_pthread_cond_init(&ctx->queuePushCond, NULL);
139 error |= ZSTD_pthread_cond_init(&ctx->queuePopCond, NULL);
140 if (error) { POOL_free(ctx); return NULL; }
141 }
142 ctx->shutdown = 0;
143 /* Allocate space for the thread handles */
144 ctx->threads = (ZSTD_pthread_t*)ZSTD_customCalloc(numThreads * sizeof(ZSTD_pthread_t), customMem);
145 ctx->threadCapacity = 0;
146 ctx->customMem = customMem;
147 /* Check for errors */
148 if (!ctx->threads || !ctx->queue) { POOL_free(ctx); return NULL; }
149 /* Initialize the threads */
150 { size_t i;
151 for (i = 0; i < numThreads; ++i) {
152 if (ZSTD_pthread_create(&ctx->threads[i], NULL, &POOL_thread, ctx)) {
153 ctx->threadCapacity = i;
154 POOL_free(ctx);
155 return NULL;
156 } }
157 ctx->threadCapacity = numThreads;
158 ctx->threadLimit = numThreads;
159 }
160 return ctx;
161 }
162
163 /*! POOL_join() :
164 Shutdown the queue, wake any sleeping threads, and join all of the threads.
165 */
POOL_join(POOL_ctx * ctx)166 static void POOL_join(POOL_ctx* ctx) {
167 /* Shut down the queue */
168 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
169 ctx->shutdown = 1;
170 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
171 /* Wake up sleeping threads */
172 ZSTD_pthread_cond_broadcast(&ctx->queuePushCond);
173 ZSTD_pthread_cond_broadcast(&ctx->queuePopCond);
174 /* Join all of the threads */
175 { size_t i;
176 for (i = 0; i < ctx->threadCapacity; ++i) {
177 ZSTD_pthread_join(ctx->threads[i]); /* note : could fail */
178 } }
179 }
180
POOL_free(POOL_ctx * ctx)181 void POOL_free(POOL_ctx *ctx) {
182 if (!ctx) { return; }
183 POOL_join(ctx);
184 ZSTD_pthread_mutex_destroy(&ctx->queueMutex);
185 ZSTD_pthread_cond_destroy(&ctx->queuePushCond);
186 ZSTD_pthread_cond_destroy(&ctx->queuePopCond);
187 ZSTD_customFree(ctx->queue, ctx->customMem);
188 ZSTD_customFree(ctx->threads, ctx->customMem);
189 ZSTD_customFree(ctx, ctx->customMem);
190 }
191
192 /*! POOL_joinJobs() :
193 * Waits for all queued jobs to finish executing.
194 */
POOL_joinJobs(POOL_ctx * ctx)195 void POOL_joinJobs(POOL_ctx* ctx) {
196 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
197 while(!ctx->queueEmpty || ctx->numThreadsBusy > 0) {
198 ZSTD_pthread_cond_wait(&ctx->queuePushCond, &ctx->queueMutex);
199 }
200 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
201 }
202
ZSTD_freeThreadPool(ZSTD_threadPool * pool)203 void ZSTD_freeThreadPool (ZSTD_threadPool* pool) {
204 POOL_free (pool);
205 }
206
POOL_sizeof(const POOL_ctx * ctx)207 size_t POOL_sizeof(const POOL_ctx* ctx) {
208 if (ctx==NULL) return 0; /* supports sizeof NULL */
209 return sizeof(*ctx)
210 + ctx->queueSize * sizeof(POOL_job)
211 + ctx->threadCapacity * sizeof(ZSTD_pthread_t);
212 }
213
214
215 /* @return : 0 on success, 1 on error */
POOL_resize_internal(POOL_ctx * ctx,size_t numThreads)216 static int POOL_resize_internal(POOL_ctx* ctx, size_t numThreads)
217 {
218 if (numThreads <= ctx->threadCapacity) {
219 if (!numThreads) return 1;
220 ctx->threadLimit = numThreads;
221 return 0;
222 }
223 /* numThreads > threadCapacity */
224 { ZSTD_pthread_t* const threadPool = (ZSTD_pthread_t*)ZSTD_customCalloc(numThreads * sizeof(ZSTD_pthread_t), ctx->customMem);
225 if (!threadPool) return 1;
226 /* replace existing thread pool */
227 ZSTD_memcpy(threadPool, ctx->threads, ctx->threadCapacity * sizeof(ZSTD_pthread_t));
228 ZSTD_customFree(ctx->threads, ctx->customMem);
229 ctx->threads = threadPool;
230 /* Initialize additional threads */
231 { size_t threadId;
232 for (threadId = ctx->threadCapacity; threadId < numThreads; ++threadId) {
233 if (ZSTD_pthread_create(&threadPool[threadId], NULL, &POOL_thread, ctx)) {
234 ctx->threadCapacity = threadId;
235 return 1;
236 } }
237 } }
238 /* successfully expanded */
239 ctx->threadCapacity = numThreads;
240 ctx->threadLimit = numThreads;
241 return 0;
242 }
243
244 /* @return : 0 on success, 1 on error */
POOL_resize(POOL_ctx * ctx,size_t numThreads)245 int POOL_resize(POOL_ctx* ctx, size_t numThreads)
246 {
247 int result;
248 if (ctx==NULL) return 1;
249 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
250 result = POOL_resize_internal(ctx, numThreads);
251 ZSTD_pthread_cond_broadcast(&ctx->queuePopCond);
252 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
253 return result;
254 }
255
256 /**
257 * Returns 1 if the queue is full and 0 otherwise.
258 *
259 * When queueSize is 1 (pool was created with an intended queueSize of 0),
260 * then a queue is empty if there is a thread free _and_ no job is waiting.
261 */
isQueueFull(POOL_ctx const * ctx)262 static int isQueueFull(POOL_ctx const* ctx) {
263 if (ctx->queueSize > 1) {
264 return ctx->queueHead == ((ctx->queueTail + 1) % ctx->queueSize);
265 } else {
266 return (ctx->numThreadsBusy == ctx->threadLimit) ||
267 !ctx->queueEmpty;
268 }
269 }
270
271
272 static void
POOL_add_internal(POOL_ctx * ctx,POOL_function function,void * opaque)273 POOL_add_internal(POOL_ctx* ctx, POOL_function function, void *opaque)
274 {
275 POOL_job job;
276 job.function = function;
277 job.opaque = opaque;
278 assert(ctx != NULL);
279 if (ctx->shutdown) return;
280
281 ctx->queueEmpty = 0;
282 ctx->queue[ctx->queueTail] = job;
283 ctx->queueTail = (ctx->queueTail + 1) % ctx->queueSize;
284 ZSTD_pthread_cond_signal(&ctx->queuePopCond);
285 }
286
POOL_add(POOL_ctx * ctx,POOL_function function,void * opaque)287 void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque)
288 {
289 assert(ctx != NULL);
290 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
291 /* Wait until there is space in the queue for the new job */
292 while (isQueueFull(ctx) && (!ctx->shutdown)) {
293 ZSTD_pthread_cond_wait(&ctx->queuePushCond, &ctx->queueMutex);
294 }
295 POOL_add_internal(ctx, function, opaque);
296 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
297 }
298
299
POOL_tryAdd(POOL_ctx * ctx,POOL_function function,void * opaque)300 int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque)
301 {
302 assert(ctx != NULL);
303 ZSTD_pthread_mutex_lock(&ctx->queueMutex);
304 if (isQueueFull(ctx)) {
305 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
306 return 0;
307 }
308 POOL_add_internal(ctx, function, opaque);
309 ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
310 return 1;
311 }
312
313
314 #else /* ZSTD_MULTITHREAD not defined */
315
316 /* ========================== */
317 /* No multi-threading support */
318 /* ========================== */
319
320
321 /* We don't need any data, but if it is empty, malloc() might return NULL. */
322 struct POOL_ctx_s {
323 int dummy;
324 };
325 static POOL_ctx g_poolCtx;
326
POOL_create(size_t numThreads,size_t queueSize)327 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
328 return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
329 }
330
331 POOL_ctx*
POOL_create_advanced(size_t numThreads,size_t queueSize,ZSTD_customMem customMem)332 POOL_create_advanced(size_t numThreads, size_t queueSize, ZSTD_customMem customMem)
333 {
334 (void)numThreads;
335 (void)queueSize;
336 (void)customMem;
337 return &g_poolCtx;
338 }
339
POOL_free(POOL_ctx * ctx)340 void POOL_free(POOL_ctx* ctx) {
341 assert(!ctx || ctx == &g_poolCtx);
342 (void)ctx;
343 }
344
POOL_joinJobs(POOL_ctx * ctx)345 void POOL_joinJobs(POOL_ctx* ctx){
346 assert(!ctx || ctx == &g_poolCtx);
347 (void)ctx;
348 }
349
POOL_resize(POOL_ctx * ctx,size_t numThreads)350 int POOL_resize(POOL_ctx* ctx, size_t numThreads) {
351 (void)ctx; (void)numThreads;
352 return 0;
353 }
354
POOL_add(POOL_ctx * ctx,POOL_function function,void * opaque)355 void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque) {
356 (void)ctx;
357 function(opaque);
358 }
359
POOL_tryAdd(POOL_ctx * ctx,POOL_function function,void * opaque)360 int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque) {
361 (void)ctx;
362 function(opaque);
363 return 1;
364 }
365
POOL_sizeof(const POOL_ctx * ctx)366 size_t POOL_sizeof(const POOL_ctx* ctx) {
367 if (ctx==NULL) return 0; /* supports sizeof NULL */
368 assert(ctx == &g_poolCtx);
369 return sizeof(*ctx);
370 }
371
372 #endif /* ZSTD_MULTITHREAD */
373