guacamole-spice-protocol/src/libguac/pool.c
2016-03-28 20:39:19 -07:00

136 lines
3.3 KiB
C

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
#include "config.h"
#include "pool.h"
#include <stdlib.h>
guac_pool* guac_pool_alloc(int size) {
pthread_mutexattr_t lock_attributes;
guac_pool* pool = malloc(sizeof(guac_pool));
/* If unable to allocate, just return NULL. */
if (pool == NULL)
return NULL;
/* Initialize empty pool */
pool->min_size = size;
pool->active = 0;
pool->__next_value = 0;
pool->__head = NULL;
pool->__tail = NULL;
/* Init lock */
pthread_mutexattr_init(&lock_attributes);
pthread_mutexattr_setpshared(&lock_attributes, PTHREAD_PROCESS_SHARED);
pthread_mutex_init(&(pool->__lock), &lock_attributes);
return pool;
}
void guac_pool_free(guac_pool* pool) {
/* Free all ints in pool */
guac_pool_int* current = pool->__head;
while (current != NULL) {
guac_pool_int* old = current;
current = current->__next;
free(old);
}
/* Destroy lock */
pthread_mutex_destroy(&(pool->__lock));
/* Free pool */
free(pool);
}
int guac_pool_next_int(guac_pool* pool) {
int value;
/* Acquire exclusive access */
pthread_mutex_lock(&(pool->__lock));
pool->active++;
/* If more integers are needed, return a new one. */
if (pool->__head == NULL || pool->__next_value < pool->min_size) {
value = pool->__next_value++;
pthread_mutex_unlock(&(pool->__lock));
return value;
}
/* Otherwise, remove first integer. */
value = pool->__head->value;
/* If only one element exists, reset pool to empty. */
if (pool->__tail == pool->__head) {
free(pool->__head);
pool->__head = NULL;
pool->__tail = NULL;
}
/* Otherwise, advance head. */
else {
guac_pool_int* old_head = pool->__head;
pool->__head = old_head->__next;
free(old_head);
}
/* Return retrieved value. */
pthread_mutex_unlock(&(pool->__lock));
return value;
}
void guac_pool_free_int(guac_pool* pool, int value) {
/* Allocate and initialize new returned value */
guac_pool_int* pool_int = malloc(sizeof(guac_pool_int));
pool_int->value = value;
pool_int->__next = NULL;
/* Acquire exclusive access */
pthread_mutex_lock(&(pool->__lock));
pool->active--;
/* If pool empty, store as sole entry. */
if (pool->__tail == NULL)
pool->__head = pool->__tail = pool_int;
/* Otherwise, append to end of pool. */
else {
pool->__tail->__next = pool_int;
pool->__tail = pool_int;
}
/* Value has been freed */
pthread_mutex_unlock(&(pool->__lock));
}