ceph/src/zstd/lib/common/pool.c

   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 <stdlib.h>  /* malloc, calloc, free */
  15 #include "pool.h"
  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 */
  28 typedef struct POOL_job_s {
  29     POOL_function function;
  30     void *opaque;
  31 } POOL_job;
  32
  33 struct 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 */
  65 static 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
 102 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
 103     return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
 104 }
 105
 106 POOL_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*) malloc(ctx->queueSize * sizeof(POOL_job));
 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 */
 149 static 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
 164 void 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
 175 size_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  */
 188 static 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 void POOL_add(void* ctxVoid, POOL_function function, void *opaque) {
 198     POOL_ctx* const ctx = (POOL_ctx*)ctxVoid;
 199     if (!ctx) { return; }
 200
 201     ZSTD_pthread_mutex_lock(&ctx->queueMutex);
 202     {   POOL_job const job = {function, opaque};
 203
 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);
 207         }
 208         /* The queue is still going => there is space */
 209         if (!ctx->shutdown) {
 210             ctx->queueEmpty = 0;
 211             ctx->queue[ctx->queueTail] = job;
 212             ctx->queueTail = (ctx->queueTail + 1) % ctx->queueSize;
 213         }
 214     }
 215     ZSTD_pthread_mutex_unlock(&ctx->queueMutex);
 216     ZSTD_pthread_cond_signal(&ctx->queuePopCond);
 217 }
 218
 219 #else  /* ZSTD_MULTITHREAD  not defined */
 220 /* No multi-threading support */
 221
 222 /* We don't need any data, but if it is empty malloc() might return NULL. */
 223 struct POOL_ctx_s {
 224     int dummy;
 225 };
 226 static POOL_ctx g_ctx;
 227
 228 POOL_ctx* POOL_create(size_t numThreads, size_t queueSize) {
 229     return POOL_create_advanced(numThreads, queueSize, ZSTD_defaultCMem);
 230 }
 231
 232 POOL_ctx* POOL_create_advanced(size_t numThreads, size_t queueSize, ZSTD_customMem customMem) {
 233     (void)numThreads;
 234     (void)queueSize;
 235     (void)customMem;
 236     return &g_ctx;
 237 }
 238
 239 void POOL_free(POOL_ctx* ctx) {
 240     assert(!ctx || ctx == &g_ctx);
 241     (void)ctx;
 242 }
 243
 244 void POOL_add(void* ctx, POOL_function function, void* opaque) {
 245     (void)ctx;
 246     function(opaque);
 247 }
 248
 249 size_t POOL_sizeof(POOL_ctx* ctx) {
 250     if (ctx==NULL) return 0;  /* supports sizeof NULL */
 251     assert(ctx == &g_ctx);
 252     return sizeof(*ctx);
 253 }
 254
 255 #endif  /* ZSTD_MULTITHREAD */