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/* queue.c
*
* This file implements the queue object and its several queueing methods.
*
* File begun on 2008-01-03 by RGerhards
*
* Copyright 2008 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 <stdlib.h>
#include <string.h>
#include <assert.h>
#include <pthread.h>
#include "rsyslog.h"
#include "queue.h"
/* static data */
/* methods */
/* first, we define type-specific handlers. The provide a generic functionality,
* but for this specific type of queue. The mapping to these handlers happens during
* queue construction. Later on, handlers are called by pointers present in the
* queue instance object.
*/
/* -------------------- fixed array -------------------- */
rsRetVal qConstructFixedArray(queue_t *pThis)
{
DEFiRet;
assert(pThis != NULL);
if((pThis->tVars.farray.pBuf = malloc(sizeof(void *) * pThis->iMaxQueueSize)) == NULL) {
ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
}
pThis->tVars.farray.head = 0;
pThis->tVars.farray.tail = 0;
finalize_it:
return iRet;
}
rsRetVal qDestructFixedArray(queue_t *pThis)
{
DEFiRet;
assert(pThis != NULL);
if(pThis->tVars.farray.pBuf != NULL)
free(pThis->tVars.farray.pBuf);
free (pThis);
return iRet;
}
rsRetVal qAddFixedArray(queue_t *pThis, void* in)
{
DEFiRet;
assert(pThis != NULL);
pThis->tVars.farray.pBuf[pThis->tVars.farray.tail] = in;
pThis->tVars.farray.tail++;
if (pThis->tVars.farray.tail == pThis->iMaxQueueSize)
pThis->tVars.farray.tail = 0;
if (pThis->tVars.farray.tail == pThis->tVars.farray.head)
pThis->full = 1;
pThis->empty = 0;
return iRet;
}
rsRetVal qDelFixedArray(queue_t *pThis, void **out)
{
DEFiRet;
assert(pThis != NULL);
*out = (void*) pThis->tVars.farray.pBuf[pThis->tVars.farray.head];
pThis->tVars.farray.head++;
if (pThis->tVars.farray.head == pThis->iMaxQueueSize)
pThis->tVars.farray.head = 0;
if (pThis->tVars.farray.head == pThis->tVars.farray.tail)
pThis->empty = 1;
pThis->full = 0;
return iRet;
}
/* --------------- end type-specific handlers -------------------- */
/* Constructor for the queue object */
rsRetVal queueConstruct(queue_t **ppThis, queueType_t qType, int iMaxQueueSize)
{
DEFiRet;
queue_t *pThis;
assert(ppThis != NULL);
dbgprintf("queueConstruct in \n");
if((pThis = (queue_t *)malloc(sizeof(queue_t))) == NULL) {
ABORT_FINALIZE(RS_RET_OUT_OF_MEMORY);
}
/* we have an object, so let's fill the properties */
pThis->iMaxQueueSize = iMaxQueueSize;
pThis->empty = 1;
pThis->full = 0;
pThis->mut = (pthread_mutex_t *) malloc (sizeof (pthread_mutex_t));
pthread_mutex_init (pThis->mut, NULL);
pThis->notFull = (pthread_cond_t *) malloc (sizeof (pthread_cond_t));
pthread_cond_init (pThis->notFull, NULL);
pThis->notEmpty = (pthread_cond_t *) malloc (sizeof (pthread_cond_t));
pthread_cond_init (pThis->notEmpty, NULL);
pThis->qType = qType;
/* set type-specific handlers */
switch(qType) {
case QUEUETYPE_FIXED_ARRAY:
pThis->qConstruct = qConstructFixedArray;
pThis->qDestruct = qDestructFixedArray;
pThis->qAdd = qAddFixedArray;
pThis->qDel = qDelFixedArray;
break;
}
/* call type-specific constructor */
CHKiRet(pThis->qConstruct(pThis));
finalize_it:
if(iRet == RS_RET_OK) {
*ppThis = pThis;
} else {
if(pThis != NULL)
free(pThis);
}
return iRet;
}
/* destructor for the queue object */
rsRetVal queueDestruct(queue_t *pThis)
{
DEFiRet;
assert(pThis != NULL);
pthread_mutex_destroy (pThis->mut);
free (pThis->mut);
pthread_cond_destroy (pThis->notFull);
free (pThis->notFull);
pthread_cond_destroy (pThis->notEmpty);
free (pThis->notEmpty);
/* type-specific destructor */
iRet = pThis->qDestruct(pThis);
return iRet;
}
/* 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.
*/
rsRetVal queueAdd(queue_t *pThis, void* in)
{
DEFiRet;
assert(pThis != NULL);
CHKiRet(pThis->qAdd(pThis, in));
finalize_it:
return iRet;
}
rsRetVal queueDel(queue_t *pThis, void **out)
{
DEFiRet;
assert(pThis != NULL);
CHKiRet(pThis->qDel(pThis, out));
finalize_it:
return iRet;
}
/*
* vi:set ai:
*/
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