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/*
* fifo.c - syslogd implementation for windows, simple and fast queue
*
* Created by Alexander Yaworsky
*
* This replacement eliminates strange page faults which were
* with glib's 2.6.3 queues.
*
* THIS SOFTWARE IS NOT COPYRIGHTED
*
* This source code is offered for use in the public domain. You may
* use, modify or distribute it freely.
*
* This code is distributed in the hope that it will be useful but
* WITHOUT ANY WARRANTY. ALL WARRANTIES, EXPRESS OR IMPLIED ARE HEREBY
* DISCLAIMED. This includes but is not limited to warranties of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
*/
#include <stdio.h>
#include <windows.h>
#include <glib.h>
#include <syslog.h>
#include <syslogd.h>
/******************************************************************************
* fifo_create
*
* Allocate and initialize fifo structure. Add an empty item to the fifo.
*/
struct fifo* fifo_create()
{
struct fifo *ret = g_malloc( sizeof(struct fifo) );
struct fifo_item *guard_item= g_malloc( sizeof(struct fifo_item) );
ret->first = guard_item;
ret->last = guard_item;
guard_item->next = NULL;
guard_item->payload = NULL;
return ret;
}
/******************************************************************************
* fifo_destroy
*
* Delete all items and free fifo structure.
*/
void fifo_destroy( struct fifo* queue )
{
struct fifo_item *item;
while( (item = queue->first) != NULL )
{
queue->first = item->next;
g_free( item );
}
g_free( queue );
}
/******************************************************************************
* fifo_push
*
* Add item to queue.
*/
void fifo_push( struct fifo* queue, void* data )
{
struct fifo_item *item = g_malloc( sizeof(struct fifo_item) );
item->next = NULL;
item->payload = data;
queue->last->next = item;
queue->last = item;
}
/******************************************************************************
* fifo_pop
*
* Extract item from queue.
* Consider four possible conditions:
* 1) next == NULL, payload == NULL: there is the only one empty item
* in the queue; leave it and return NULL
* 2) next == NULL, payload != NULL: leave item and return its payload;
* set item's payload NULL
* 3) next != NULL, payload == NULL: queue was empty when a new item was
* added; free this item and go to the next one
* 4) next != NULL, payload != NULL: free item and return its payload
*/
void* fifo_pop( struct fifo* queue )
{
for(;;)
{
struct fifo_item *item = queue->first;
struct fifo_item *next = InterlockedExchangePointer( &item->next, NULL );
void *data = item->payload;
item->payload = NULL;
if( next )
{
queue->first = next;
g_free( item );
}
if( data )
return data;
if( !next )
return NULL;
}
}
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