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/**
* @file job_queue.c
*
* @brief Implementation of job_queue_t
*
*/
/*
* Copyright (C) 2005-2006 Martin Willi
* Copyright (C) 2005 Jan Hutter
* Hochschule fuer Technik Rapperswil
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*/
#include <stdlib.h>
#include <pthread.h>
#include "job_queue.h"
#include <utils/linked_list.h>
typedef struct private_job_queue_t private_job_queue_t;
/**
* @brief Private Variables and Functions of job_queue class
*
*/
struct private_job_queue_t {
/**
* public members
*/
job_queue_t public;
/**
* The jobs are stored in a linked list
*/
linked_list_t *list;
/**
* access to linked_list is locked through this mutex
*/
pthread_mutex_t mutex;
/**
* If the queue is empty a thread has to wait
* This condvar is used to wake up such a thread
*/
pthread_cond_t condvar;
};
/**
* implements job_queue_t.get_count
*/
static int get_count(private_job_queue_t *this)
{
int count;
pthread_mutex_lock(&(this->mutex));
count = this->list->get_count(this->list);
pthread_mutex_unlock(&(this->mutex));
return count;
}
/**
* implements job_queue_t.get
*/
static job_t *get(private_job_queue_t *this)
{
int oldstate;
job_t *job;
pthread_mutex_lock(&(this->mutex));
/* go to wait while no jobs available */
while(this->list->get_count(this->list) == 0)
{
/* add mutex unlock handler for cancellation, enable cancellation */
pthread_cleanup_push((void(*)(void*))pthread_mutex_unlock, (void*)&(this->mutex));
pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &oldstate);
pthread_cond_wait( &(this->condvar), &(this->mutex));
/* reset cancellation, remove mutex-unlock handler (without executing) */
pthread_setcancelstate(oldstate, NULL);
pthread_cleanup_pop(0);
}
this->list->remove_first(this->list, (void **)&job);
pthread_mutex_unlock(&(this->mutex));
return job;
}
/**
* implements function job_queue_t.add
*/
static void add(private_job_queue_t *this, job_t *job)
{
pthread_mutex_lock(&(this->mutex));
this->list->insert_last(this->list,job);
pthread_cond_signal( &(this->condvar));
pthread_mutex_unlock(&(this->mutex));
}
/**
* implements job_queue_t.destroy
*/
static void job_queue_destroy (private_job_queue_t *this)
{
this->list->destroy_offset(this->list, offsetof(job_t, destroy));
free(this);
}
/*
*
* Documented in header
*/
job_queue_t *job_queue_create(void)
{
private_job_queue_t *this = malloc_thing(private_job_queue_t);
this->public.get_count = (int(*)(job_queue_t*))get_count;
this->public.get = (job_t*(*)(job_queue_t*))get;
this->public.add = (void(*)(job_queue_t*, job_t*))add;
this->public.destroy = (void(*)(job_queue_t*))job_queue_destroy;
this->list = linked_list_create();
pthread_mutex_init(&(this->mutex), NULL);
pthread_cond_init(&(this->condvar), NULL);
return (&this->public);
}
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