module/zstd/lib/common/pool.c

   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 <stddef.h>    /* size_t */
  14 #include "debug.h"     /* assert */
  15 #include "zstd_internal.h"  /* ZSTD_malloc, ZSTD_free */
  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  */
  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
 108 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
 109     return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
 110 }
 111
 112 POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize,
 113                                ZSTD_customMem customMem) {
 114     POOL_ctx* ctx;
 115     /* Check parameters */
 116     if (!numThreads) { return NULL; }
 117     /* Allocate the context and zero initialize */
 118     ctx = (POOL_ctx*)ZSTD_calloc(sizeof(POOL_ctx), customMem);
 119     if (!ctx) { return NULL; }
 120     /* Initialize the job queue.
 121      * It needs one extra space since one space is wasted to differentiate
 122      * empty and full queues.
 123      */
 124     ctx->queueSize = queueSize + 1;
 125     ctx->queue = (POOL_job*)ZSTD_malloc(ctx->queueSize * sizeof(POOL_job), customMem);
 126     ctx->queueHead = 0;
 127     ctx->queueTail = 0;
 128     ctx->numThreadsBusy = 0;
 129     ctx->queueEmpty = 1;
 130     {
 131         int error = 0;
 132         error |= ZSTD_pthread_mutex_init(&ctx->queueMutex, NULL);
 133         error |= ZSTD_pthread_cond_init(&ctx->queuePushCond, NULL);
 134         error |= ZSTD_pthread_cond_init(&ctx->queuePopCond, NULL);
 135         if (error) { POOL_free(ctx); return NULL; }
 136     }
 137     ctx->shutdown = 0;
 138     /* Allocate space for the thread handles */
 139     ctx->threads = (ZSTD_pthread_t*)ZSTD_malloc(numThreads * sizeof(ZSTD_pthread_t), customMem);
 140     ctx->threadCapacity = 0;
 141     ctx->customMem = customMem;
 142     /* Check for errors */
 143     if (!ctx->threads || !ctx->queue) { POOL_free(ctx); return NULL; }
 144     /* Initialize the threads */
 145     {   size_t i;
 146         for (i = 0; i < numThreads; ++i) {
 147             if (ZSTD_pthread_create(&ctx->threads[i], NULL, &POOL_thread, ctx)) {
 148                 ctx->threadCapacity = i;
 149                 POOL_free(ctx);
 150                 return NULL;
 151         }   }
 152         ctx->threadCapacity = numThreads;
 153         ctx->threadLimit = numThreads;
 154     }
 155     return ctx;
 156 }
 157
 158 /*! POOL_join() :
 159     Shutdown the queue, wake any sleeping threads, and join all of the threads.
 160 */
 161 static void POOL_join(POOL_ctx* ctx) {
 162     /* Shut down the queue */
 163     ZSTD_pthread_mutex_lock(&ctx->queueMutex);
 164     ctx->shutdown = 1;
 165     ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
 166     /* Wake up sleeping threads */
 167     ZSTD_pthread_cond_broadcast(&ctx->queuePushCond);
 168     ZSTD_pthread_cond_broadcast(&ctx->queuePopCond);
 169     /* Join all of the threads */
 170     {   size_t i;
 171         for (i = 0; i < ctx->threadCapacity; ++i) {
 172             ZSTD_pthread_join(ctx->threads[i], NULL);  /* note : could fail */
 173     }   }
 174 }
 175
 176 void POOL_free(POOL_ctx *ctx) {
 177     if (!ctx) { return; }
 178     POOL_join(ctx);
 179     ZSTD_pthread_mutex_destroy(&ctx->queueMutex);
 180     ZSTD_pthread_cond_destroy(&ctx->queuePushCond);
 181     ZSTD_pthread_cond_destroy(&ctx->queuePopCond);
 182     ZSTD_free(ctx->queue, ctx->customMem);
 183     ZSTD_free(ctx->threads, ctx->customMem);
 184     ZSTD_free(ctx, ctx->customMem);
 185 }
 186
 187
 188
 189 size_t POOL_sizeof(POOL_ctx *ctx) {
 190     if (ctx==NULL) return 0;  /* supports sizeof NULL */
 191     return sizeof(*ctx)
 192         + ctx->queueSize * sizeof(POOL_job)
 193         + ctx->threadCapacity * sizeof(ZSTD_pthread_t);
 194 }
 195
 196
 197 /* @return : 0 on success, 1 on error */
 198 static int POOL_resize_internal(POOL_ctx* ctx, size_t numThreads)
 199 {
 200     if (numThreads <= ctx->threadCapacity) {
 201         if (!numThreads) return 1;
 202         ctx->threadLimit = numThreads;
 203         return 0;
 204     }
 205     /* numThreads > threadCapacity */
 206     {   ZSTD_pthread_t* const threadPool = (ZSTD_pthread_t*)ZSTD_malloc(numThreads * sizeof(ZSTD_pthread_t), ctx->customMem);
 207         if (!threadPool) return 1;
 208         /* replace existing thread pool */
 209         memcpy(threadPool, ctx->threads, ctx->threadCapacity * sizeof(*threadPool));
 210         ZSTD_free(ctx->threads, ctx->customMem);
 211         ctx->threads = threadPool;
 212         /* Initialize additional threads */
 213         {   size_t threadId;
 214             for (threadId = ctx->threadCapacity; threadId < numThreads; ++threadId) {
 215                 if (ZSTD_pthread_create(&threadPool[threadId], NULL, &POOL_thread, ctx)) {
 216                     ctx->threadCapacity = threadId;
 217                     return 1;
 218             }   }
 219     }   }
 220     /* successfully expanded */
 221     ctx->threadCapacity = numThreads;
 222     ctx->threadLimit = numThreads;
 223     return 0;
 224 }
 225
 226 /* @return : 0 on success, 1 on error */
 227 int POOL_resize(POOL_ctx* ctx, size_t numThreads)
 228 {
 229     int result;
 230     if (ctx==NULL) return 1;
 231     ZSTD_pthread_mutex_lock(&ctx->queueMutex);
 232     result = POOL_resize_internal(ctx, numThreads);
 233     ZSTD_pthread_cond_broadcast(&ctx->queuePopCond);
 234     ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
 235     return result;
 236 }
 237
 238 /**
 239  * Returns 1 if the queue is full and 0 otherwise.
 240  *
 241  * When queueSize is 1 (pool was created with an intended queueSize of 0),
 242  * then a queue is empty if there is a thread free _and_ no job is waiting.
 243  */
 244 static int isQueueFull(POOL_ctx const* ctx) {
 245     if (ctx->queueSize > 1) {
 246         return ctx->queueHead == ((ctx->queueTail + 1) % ctx->queueSize);
 247     } else {
 248         return (ctx->numThreadsBusy == ctx->threadLimit) ||
 249                !ctx->queueEmpty;
 250     }
 251 }
 252
 253
 254 static void POOL_add_internal(POOL_ctx* ctx, POOL_function function, void *opaque)
 255 {
 256     POOL_job const job = {function, opaque};
 257     assert(ctx != NULL);
 258     if (ctx->shutdown) return;
 259
 260     ctx->queueEmpty = 0;
 261     ctx->queue[ctx->queueTail] = job;
 262     ctx->queueTail = (ctx->queueTail + 1) % ctx->queueSize;
 263     ZSTD_pthread_cond_signal(&ctx->queuePopCond);
 264 }
 265
 266 void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque)
 267 {
 268     assert(ctx != NULL);
 269     ZSTD_pthread_mutex_lock(&ctx->queueMutex);
 270     /* Wait until there is space in the queue for the new job */
 271     while (isQueueFull(ctx) && (!ctx->shutdown)) {
 272         ZSTD_pthread_cond_wait(&ctx->queuePushCond, &ctx->queueMutex);
 273     }
 274     POOL_add_internal(ctx, function, opaque);
 275     ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
 276 }
 277
 278
 279 int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque)
 280 {
 281     assert(ctx != NULL);
 282     ZSTD_pthread_mutex_lock(&ctx->queueMutex);
 283     if (isQueueFull(ctx)) {
 284         ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
 285         return 0;
 286     }
 287     POOL_add_internal(ctx, function, opaque);
 288     ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
 289     return 1;
 290 }
 291
 292
 293 #else  /* ZSTD_MULTITHREAD  not defined */
 294
 295 /* ========================== */
 296 /* No multi-threading support */
 297 /* ========================== */
 298
 299
 300 /* We don't need any data, but if it is empty, malloc() might return NULL. */
 301 struct POOL_ctx_s {
 302     int dummy;
 303 };
 304 static POOL_ctx g_ctx;
 305
 306 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
 307     return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
 308 }
 309
 310 POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize, ZSTD_customMem customMem) {
 311     (void)numThreads;
 312     (void)queueSize;
 313     (void)customMem;
 314     return &g_ctx;
 315 }
 316
 317 void POOL_free(POOL_ctx* ctx) {
 318     assert(!ctx || ctx == &g_ctx);
 319     (void)ctx;
 320 }
 321
 322 int POOL_resize(POOL_ctx* ctx, size_t numThreads) {
 323     (void)ctx; (void)numThreads;
 324     return 0;
 325 }
 326
 327 void POOL_add(POOL_ctx* ctx, POOL_function function, void* opaque) {
 328     (void)ctx;
 329     function(opaque);
 330 }
 331
 332 int POOL_tryAdd(POOL_ctx* ctx, POOL_function function, void* opaque) {
 333     (void)ctx;
 334     function(opaque);
 335     return 1;
 336 }
 337
 338 size_t POOL_sizeof(POOL_ctx* ctx) {
 339     if (ctx==NULL) return 0;  /* supports sizeof NULL */
 340     assert(ctx == &g_ctx);
 341     return sizeof(*ctx);
 342 }
 343
 344 #endif  /* ZSTD_MULTITHREAD */