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/* threads.c
*
* This file implements threading support helpers (and maybe the thread object)
* for rsyslog.
*
* File begun on 2007-12-14 by RGerhards
*
* Copyright 2007 Rainer Gerhards and Adiscon GmbH.
*
* This file is part of rsyslog.
*
* Rsyslog 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 3 of the License, or
* (at your option) any later version.
*
* Rsyslog 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 Rsyslog. If not, see <http://www.gnu.org/licenses/>.
*
* A copy of the GPL can be found in the file "COPYING" in this distribution.
*/
#include "config.h"
#include "rsyslog.h"
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <pthread.h>
#include <assert.h>
#include "syslogd.h"
#include "linkedlist.h"
#include "threads.h"
/* static data */
int iMainMsgQueueSize;
msgQueue *pMsgQueue = NULL;
/* linked list of currently-known threads */
static linkedList_t llThrds;
/* methods */
/* Construct a new thread object
*/
static rsRetVal thrdConstruct(thrdInfo_t **pThis)
{
thrdInfo_t *pNew;
if((pNew = calloc(1, sizeof(thrdInfo_t))) == NULL)
return RS_RET_OUT_OF_MEMORY;
/* OK, we got the element, now initialize members that should
* not be zero-filled.
*/
*pThis = pNew;
return RS_RET_OK;
}
/* Destructs a thread object. The object must not be linked to the
* linked list of threads. Please note that the thread should have been
* stopped before. If not, we try to do it.
*/
static rsRetVal thrdDestruct(thrdInfo_t *pThis)
{
assert(pThis != NULL);
if(pThis->bIsActive == 1) {
thrdTerminate(pThis);
}
free(pThis);
return RS_RET_OK;
}
/* terminate a thread gracefully. It's termination sync state is taken into
* account.
*/
rsRetVal thrdTerminate(thrdInfo_t *pThis)
{
assert(pThis != NULL);
if(pThis->eTermTool == eTermSync_SIGNAL) {
pthread_kill(pThis->thrdID, SIGUSR2);
pthread_join(pThis->thrdID, NULL);
/* TODO: TIMEOUT! */
} else if(pThis->eTermTool == eTermSync_NONE) {
pthread_cancel(pThis->thrdID);
}
pThis->bIsActive = 0;
return RS_RET_OK;
}
/* initialize the thread-support subsystem
* must be called once at the start of the program
*/
rsRetVal thrdInit(void)
{
DEFiRet;
iRet = llInit(&llThrds, thrdDestruct, NULL, NULL);
return iRet;
}
/* de-initialize the thread subsystem
* must be called once at the end of the program
*/
rsRetVal thrdExit(void)
{
DEFiRet;
iRet = llDestroy(&llThrds);
return iRet;
}
/* queue functions (may be migrated to some other file...)
*/
msgQueue *queueInit (void)
{
msgQueue *q;
q = (msgQueue *)malloc(sizeof(msgQueue));
if (q == NULL) return (NULL);
if((q->pbuf = malloc(sizeof(void *) * iMainMsgQueueSize)) == NULL) {
free(q);
return NULL;
}
q->empty = 1;
q->full = 0;
q->head = 0;
q->tail = 0;
q->mut = (pthread_mutex_t *) malloc (sizeof (pthread_mutex_t));
pthread_mutex_init (q->mut, NULL);
q->notFull = (pthread_cond_t *) malloc (sizeof (pthread_cond_t));
pthread_cond_init (q->notFull, NULL);
q->notEmpty = (pthread_cond_t *) malloc (sizeof (pthread_cond_t));
pthread_cond_init (q->notEmpty, NULL);
return (q);
}
void queueDelete (msgQueue *q)
{
pthread_mutex_destroy (q->mut);
free (q->mut);
pthread_cond_destroy (q->notFull);
free (q->notFull);
pthread_cond_destroy (q->notEmpty);
free (q->notEmpty);
free(q->pbuf);
free (q);
}
/* In queueAdd() and queueDel() we have a potential race condition. If a message
* is dequeued and at the same time a message is enqueued and the queue is either
* full or empty, the full (or empty) indicator may be invalidly updated. HOWEVER,
* this does not cause any real problems. No queue pointers can be wrong. And even
* if one of the flags is set invalidly, that does not pose a real problem. If
* "full" is invalidly set, at mose one message might be lost, if we are already in
* a timeout situation (this is quite acceptable). And if "empty" is accidently set,
* the receiver will not continue the inner loop, but break out of the outer. So no
* harm is done at all. For this reason, I do not yet use a mutex to guard the two
* flags - there would be a notable performance hit with, IMHO, no gain in stability
* or functionality. But anyhow, now it's documented...
* rgerhards, 2007-09-20
* NOTE: this comment does not really apply - the callers handle the mutex, so it
* *is* guarded.
*/
void queueAdd (msgQueue *q, void* in)
{
q->pbuf[q->tail] = in;
q->tail++;
if (q->tail == iMainMsgQueueSize)
q->tail = 0;
if (q->tail == q->head)
q->full = 1;
q->empty = 0;
return;
}
void queueDel(msgQueue *q, void **out)
{
*out = (void*) q->pbuf[q->head];
q->head++;
if (q->head == iMainMsgQueueSize)
q->head = 0;
if (q->head == q->tail)
q->empty = 1;
q->full = 0;
return;
}
/*
* vi:set ai:
*/
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