/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright 2013 Olaf Wintermann. 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.
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "atomic.h"
#include "thrpool.h"
static threadpool_job kill_job;
threadpool_t* threadpool_new(int min, int max) {
log_ereport(LOG_VERBOSE, "new threadpool (min: %d, max: %d)", min, max);
threadpool_t *pool = malloc(sizeof(threadpool_t));
pool->queue = NULL;
pool->queue_len = 0;
pool->num_idle = 0;
pool->min_threads = min;
pool->max_threads = max;
pool->num_threads = 0;
pthread_mutex_init(&pool->queue_lock, NULL);
pthread_mutex_init(&pool->avlbl_lock, NULL);
pthread_cond_init(&pool->available, NULL);
/* create pool threads */
for(int i=0;i<min;i++) {
pthread_t t;
if (pthread_create(&t, NULL, threadpool_func, pool) != 0) {
perror("Error: threadpool_new: pthread_create");
return NULL;
}
}
return pool;
}
void* threadpool_func(void *data) {
threadpool_t *pool = (threadpool_t*)data;
ws_atomic_inc32(&pool->num_threads);
for(;;) {
threadpool_job *job = threadpool_get_job(pool);
if(job == &kill_job) {
break;
}
job->callback(job->data);
free(job);
}
ws_atomic_dec32(&pool->num_threads);
return NULL;
}
threadpool_job* threadpool_get_job(threadpool_t *pool) {
pthread_mutex_lock(&pool->queue_lock);
threadpool_job *job = NULL;
pool->num_idle++;
while(job == NULL) {
if(pool->queue_len == 0) {
pthread_cond_wait(&pool->available, &pool->queue_lock);
continue;
} else {
pool_queue_t *q = pool->queue;
job = q->job;
pool->queue = q->next;
pool->queue_len--;
free(q);
}
}
pool->num_idle--;
pthread_mutex_unlock(&pool->queue_lock);
return job;
}
void threadpool_run(threadpool_t *pool, job_callback_f func, void *data) {
threadpool_job *job = malloc(sizeof(threadpool_job));
job->callback = func;
job->data = data;
pthread_mutex_lock(&pool->queue_lock);
threadpool_enqueue_job(pool, job);
int create_thread = 0;
int destroy_thread = 0;
int diff = pool->queue_len - pool->num_idle;
if(diff > 0 && pool->num_threads < pool->max_threads) {
create_thread = 1;
} else if(diff < 0 && pool->num_threads > pool->min_threads) {
destroy_thread = 1;
}
//if(pool->queue_len == 1) {
pthread_cond_signal(&pool->available);
//}
if(create_thread) {
pthread_t t;
if (pthread_create(&t, NULL, threadpool_func, pool) != 0) {
perror("Error: threadpool_run: pthread_create");
}
}
if(destroy_thread) {
threadpool_enqueue_job(pool, &kill_job);
pthread_cond_signal(&pool->available);
}
pthread_mutex_unlock(&pool->queue_lock);
}
void threadpool_enqueue_job(threadpool_t *pool, threadpool_job *job) {
pool_queue_t *q = malloc(sizeof(pool_queue_t));
q->job = job;
q->next = NULL;
if(pool->queue == NULL) {
pool->queue = q;
} else {
pool_queue_t *last_elem = pool->queue;
while(last_elem->next != NULL) {
last_elem = last_elem->next;
}
last_elem->next = q;
}
pool->queue_len++;
}