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/*
* This file is part of the Green End SFTP Server.
* Copyright (C) 2007, 2011 Richard Kettlewell
*
* 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.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA
*/
/** @file queue.h @brief Thread pool/queue implementation */
#include "sftpserver.h"
#include "queue.h"
#include "alloc.h"
#include "debug.h"
#include "utils.h"
#include "thread.h"
#include <stdlib.h>
#include <string.h>
#if NTHREADS > 1
/** @brief One job in a queue */
struct queuejob {
/** @brief Next job or a null pointer */
struct queuejob *next;
/** @brief Job */
void *job;
};
/** @brief Definition of a queue */
struct queue {
/** @brief Head of queue */
struct queuejob *jobs;
/** @brief Where to store new tail of queue */
struct queuejob **jobstail;
/** @brief Mutex protecting queue */
pthread_mutex_t m;
/** @brief Condition variable for signaling changes to queue */
pthread_cond_t c;
/** @brief Queue-specific callbacks */
const struct queuedetails *details;
/** @brief Number of worker threads */
int nthreads;
/** @brief Table of worker thread IDs */
pthread_t *threads;
/** @brief Set when queue is being destroyed */
int join;
};
/** @brief Implementation of worker thread
* @param vq Queue pointer
* @return A null pointer
*/
static void *queue_thread(void *vq) {
struct queue *const q = vq;
struct queuejob *qj;
struct allocator a;
void *workerdata;
workerdata = q->details->init();
ferrcheck(pthread_mutex_lock(&q->m));
while(q->jobs || !q->join) {
if(q->jobs) {
/* Pick job of front of queue */
qj = q->jobs;
if(!(q->jobs = qj->next))
q->jobstail = &q->jobs;
/* Don't hold lock while executing job */
ferrcheck(pthread_mutex_unlock(&q->m));
sftp_alloc_init(&a);
q->details->worker(qj->job, workerdata, &a);
sftp_alloc_destroy(&a);
free(qj);
ferrcheck(pthread_mutex_lock(&q->m));
} else {
/* Nothing's happening, wait for a signal */
ferrcheck(pthread_cond_wait(&q->c, &q->m));
}
}
ferrcheck(pthread_mutex_unlock(&q->m));
q->details->cleanup(workerdata);
return 0;
}
void queue_init(struct queue **qr,
const struct queuedetails *details,
int nthreads) {
int n;
struct queue *q;
q = xmalloc(sizeof *q);
memset(q, 0, sizeof *q);
q->jobs = 0;
q->jobstail = &q->jobs;
ferrcheck(pthread_mutex_init(&q->m, 0));
ferrcheck(pthread_cond_init(&q->c, 0));
q->details = details;
q->nthreads = nthreads;
q->threads = xcalloc(nthreads, sizeof (pthread_t));
q->join = 0;
for(n = 0; n < q->nthreads; ++n)
ferrcheck(pthread_create(&q->threads[n], 0, queue_thread, q));
*qr = q;
}
void queue_add(struct queue *q, void *job) {
struct queuejob *qj;
qj = xmalloc(sizeof *qj);
qj->next = 0;
qj->job = job;
ferrcheck(pthread_mutex_lock(&q->m));
*q->jobstail = qj;
q->jobstail = &qj->next;
ferrcheck(pthread_cond_signal(&q->c)); /* any one thread */
ferrcheck(pthread_mutex_unlock(&q->m));
}
void queue_destroy(struct queue *q) {
int n;
if(q) {
ferrcheck(pthread_mutex_lock(&q->m));
q->join = 1;
ferrcheck(pthread_cond_broadcast(&q->c)); /* all threads */
ferrcheck(pthread_mutex_unlock(&q->m));
for(n = 0; n < q->nthreads; ++n)
ferrcheck(pthread_join(q->threads[n], 0));
free(q->threads);
free(q);
}
}
#endif
/*
Local Variables:
c-basic-offset:2
comment-column:40
fill-column:79
indent-tabs-mode:nil
End:
*/
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