linux thread pool demo
threadpool.h文件
/* * Copyright (c) 2013, Mathias Brossard <[email protected]>. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef _THREADPOOL_H_ #define _THREADPOOL_H_ /** * @file threadpool.h * @brief Threadpool Header File */ typedef struct threadpool_t threadpool_t; typedef enum { threadpool_invalid = -1, threadpool_lock_failure = -2, threadpool_queue_full = -3, threadpool_shutdown = -4, threadpool_thread_failure = -5 } threadpool_error_t; typedef enum { threadpool_graceful = 1 } threadpool_destroy_flags_t; /** * @function threadpool_create * @brief Creates a threadpool_t object. * @param thread_count Number of worker threads. * @param queue_size Size of the queue. * @param flags Unused parameter. * @return a newly created thread pool or NULL */ threadpool_t *threadpool_create(int thread_count, int queue_size, int flags); /** * @function threadpool_add * @brief add a new task in the queue of a thread pool * @param pool Thread pool to which add the task. * @param function Pointer to the function that will perform the task. * @param argument Argument to be passed to the function. * @param flags Unused parameter. * @return 0 if all goes well, negative values in case of error (@see * threadpool_error_t for codes). */ int threadpool_add(threadpool_t *pool, void (*routine)(void *), void *arg, int flags); /** * @function threadpool_destroy * @brief Stops and destroys a thread pool. * @param pool Thread pool to destroy. * @param flags Flags for shutdown * * Known values for flags are 0 (default) and threadpool_graceful in * which case the thread pool doesn't accept any new tasks but * processes all pending tasks before shutdown. */ int threadpool_destroy(threadpool_t *pool, int flags); #endif /* _THREADPOOL_H_ */
threadpool.c
/* * Copyright (c) 2013, Mathias Brossard <[email protected]>. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ /** * @file threadpool.c * @brief Threadpool implementation file */ #include <stdlib.h> #include <pthread.h> #include <unistd.h> #include "threadpool.h" typedef enum { immediate_shutdown = 1, graceful_shutdown = 2 } threadpool_shutdown_t; /** * @struct threadpool_task * @brief the work struct * * @var function Pointer to the function that will perform the task. * @var argument Argument to be passed to the function. */ typedef struct { void (*function)(void *); void *argument; } threadpool_task_t; /** * @struct threadpool * @brief The threadpool struct * * @var notify Condition variable to notify worker threads. * @var threads Array containing worker threads ID. * @var thread_count Number of threads * @var queue Array containing the task queue. * @var queue_size Size of the task queue. * @var head Index of the first element. * @var tail Index of the next element. * @var count Number of pending tasks * @var shutdown Flag indicating if the pool is shutting down * @var started Number of started threads */ struct threadpool_t { pthread_mutex_t lock; pthread_cond_t notify; pthread_t *threads; threadpool_task_t *queue; int thread_count; int queue_size; int head; int tail; int count; int shutdown; int started; }; /** * @function void *threadpool_thread(void *threadpool) * @brief the worker thread * @param threadpool the pool which own the thread */ static void *threadpool_thread(void *threadpool); int threadpool_free(threadpool_t *pool); threadpool_t *threadpool_create(int thread_count, int queue_size, int flags) { threadpool_t *pool; int i; /* TODO: Check for negative or otherwise very big input parameters */ if((pool = (threadpool_t *)malloc(sizeof(threadpool_t))) == NULL) { goto err; } /* Initialize */ pool->thread_count = 0; pool->queue_size = queue_size; pool->head = pool->tail = pool->count = 0; pool->shutdown = pool->started = 0; /* Allocate thread and task queue */ pool->threads = (pthread_t *)malloc(sizeof(pthread_t) * thread_count); pool->queue = (threadpool_task_t *)malloc (sizeof(threadpool_task_t) * queue_size); /* Initialize mutex and conditional variable first */ if((pthread_mutex_init(&(pool->lock), NULL) != 0) || (pthread_cond_init(&(pool->notify), NULL) != 0) || (pool->threads == NULL) || (pool->queue == NULL)) { goto err; } /* Start worker threads */ for(i = 0; i < thread_count; i++) { if(pthread_create(&(pool->threads[i]), NULL, threadpool_thread, (void*)pool) != 0) { threadpool_destroy(pool, 0); return NULL; } pool->thread_count++; pool->started++; } return pool; err: if(pool) { threadpool_free(pool); } return NULL; } int threadpool_add(threadpool_t *pool, void (*function)(void *), void *argument, int flags) { int err = 0; int next; if(pool == NULL || function == NULL) { return threadpool_invalid; } if(pthread_mutex_lock(&(pool->lock)) != 0) { return threadpool_lock_failure; } next = pool->tail + 1; next = (next == pool->queue_size) ? 0 : next; do { /* Are we full ? */ if(pool->count == pool->queue_size) { err = threadpool_queue_full; break; } /* Are we shutting down ? */ if(pool->shutdown) { err = threadpool_shutdown; break; } /* Add task to queue */ pool->queue[pool->tail].function = function; pool->queue[pool->tail].argument = argument; pool->tail = next; pool->count += 1; /* pthread_cond_broadcast */ if(pthread_cond_signal(&(pool->notify)) != 0) { err = threadpool_lock_failure; break; } } while(0); if(pthread_mutex_unlock(&pool->lock) != 0) { err = threadpool_lock_failure; } return err; } int threadpool_destroy(threadpool_t *pool, int flags) { int i, err = 0; if(pool == NULL) { return threadpool_invalid; } if(pthread_mutex_lock(&(pool->lock)) != 0) { return threadpool_lock_failure; } do { /* Already shutting down */ if(pool->shutdown) { err = threadpool_shutdown; break; } pool->shutdown = (flags & threadpool_graceful) ? graceful_shutdown : immediate_shutdown; /* Wake up all worker threads */ if((pthread_cond_broadcast(&(pool->notify)) != 0) || (pthread_mutex_unlock(&(pool->lock)) != 0)) { err = threadpool_lock_failure; break; } /* Join all worker thread */ for(i = 0; i < pool->thread_count; i++) { if(pthread_join(pool->threads[i], NULL) != 0) { err = threadpool_thread_failure; } } } while(0); /* Only if everything went well do we deallocate the pool */ if(!err) { threadpool_free(pool); } return err; } int threadpool_free(threadpool_t *pool) { if(pool == NULL || pool->started > 0) { return -1; } /* Did we manage to allocate ? */ if(pool->threads) { free(pool->threads); free(pool->queue); /* Because we allocate pool->threads after initializing the mutex and condition variable, we're sure they're initialized. Let's lock the mutex just in case. */ pthread_mutex_lock(&(pool->lock)); pthread_mutex_destroy(&(pool->lock)); pthread_cond_destroy(&(pool->notify)); } free(pool); return 0; } static void *threadpool_thread(void *threadpool) { threadpool_t *pool = (threadpool_t *)threadpool; threadpool_task_t task; for(;;) { /* Lock must be taken to wait on conditional variable */ pthread_mutex_lock(&(pool->lock)); /* Wait on condition variable, check for spurious wakeups. When returning from pthread_cond_wait(), we own the lock. */ while((pool->count == 0) && (!pool->shutdown)) { pthread_cond_wait(&(pool->notify), &(pool->lock)); } if((pool->shutdown == immediate_shutdown) || ((pool->shutdown == graceful_shutdown) && (pool->count == 0))) { break; } /* Grab our task */ task.function = pool->queue[pool->head].function; task.argument = pool->queue[pool->head].argument; pool->head += 1; pool->head = (pool->head == pool->queue_size) ? 0 : pool->head; pool->count -= 1; /* Unlock */ pthread_mutex_unlock(&(pool->lock)); /* Get to work */ (*(task.function))(task.argument); } pool->started--; pthread_mutex_unlock(&(pool->lock)); pthread_exit(NULL); return(NULL); }
normal thread pool demo
#define THREAD 32
#define QUEUE 256
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <assert.h>
#include "threadpool.h"
int tasks = 0, done = 0;
pthread_mutex_t lock;
void dummy_task(void *arg) {
usleep(10000);
pthread_mutex_lock(&lock);
done++;
pthread_mutex_unlock(&lock);
}
int main(int argc, char **argv)
{
threadpool_t *pool;
pthread_mutex_init(&lock, NULL);
assert((pool = threadpool_create(THREAD, QUEUE, 0)) != NULL);
fprintf(stderr, "Pool started with %d threads and "
"queue size of %d\n", THREAD, QUEUE);
while(threadpool_add(pool, &dummy_task, NULL, 0) == 0) {
pthread_mutex_lock(&lock);
tasks++;
pthread_mutex_unlock(&lock);
}
fprintf(stderr, "Added %d tasks\n", tasks);
while((tasks / 2) > done) {
usleep(10000);
}
assert(threadpool_destroy(pool, 0) == 0);
fprintf(stderr, "Did %d tasks\n", done);
return 0;
}
shut down threadpool demo
#include <stdio.h>
#include <pthread.h>
#include <unistd.h>
#include <assert.h>
#include "threadpool.h"
#define THREAD 4
#define SIZE 8192
threadpool_t *pool;
int left;
pthread_mutex_t lock;
int error;
void dummy_task(void *arg) {
usleep(100);
pthread_mutex_lock(&lock);
left--;
pthread_mutex_unlock(&lock);
}
int main(int argc, char **argv)
{
int i;
pthread_mutex_init(&lock, NULL);
/* Testing immediate shutdown */
left = SIZE;
pool = threadpool_create(THREAD, SIZE, 0);
for(i = 0; i < SIZE; i++) {
assert(threadpool_add(pool, &dummy_task, NULL, 0) == 0);
}
assert(threadpool_destroy(pool, 0) == 0);
assert(left > 0);
/* Testing graceful shutdown */
left = SIZE;
pool = threadpool_create(THREAD, SIZE, 0);
for(i = 0; i < SIZE; i++) {
assert(threadpool_add(pool, &dummy_task, NULL, 0) == 0);
}
assert(threadpool_destroy(pool, threadpool_graceful) == 0);
assert(left == 0);
pthread_mutex_destroy(&lock);
return 0;
}