/* ARISA - simple pointer queue implementation, which got complex...
 * Copyright (C) 2003, 2004 Carl Ritson
 *
 * 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
 */

#include "arisa.h"
#include <unistd.h>
#include <errno.h>

pqueue_t *pqueue_init(pqueue_t *q, int lockable) {
	if(q == NULL)
		q = xalloc(sizeof(pqueue_t));
	if(lockable > 0) {
		q->lock = xalloc(sizeof(lock_t));
		LOCK_INIT(q->lock);
	} else
		q->lock = NULL;
	q->front 	= NULL;
	q->back		= NULL;
	q->length 	= 0;
	q->fd		= -1;
	return q;
}

static pqueueb_t *pqueue_bucket_init(void *ptr) {
	pqueueb_t *b = xalloc(sizeof(pqueueb_t));
	b->ptr 	= ptr;
	b->next = NULL;
	return b;
}

static void pqueue_bucket_free(pqueueb_t *b) {
	xfree(b);
}

/* clear, but don't free, for non-malloc'ed pqueues */
void pqueue_clear(pqueue_t *q, void (*ptrfree)(void *), int doclose) {
	pqueueb_t *p,*b;
	if(q->lock != NULL)
		LOCKR(q->lock);

	b = q->front;
	while(b != NULL) {
		p = b;
		b = b->next;
		if(ptrfree != NULL)
			ptrfree(p->ptr);
		pqueue_bucket_free(p);
	}
	q->front	= NULL;
	q->back		= NULL;
	q->length	= 0;
	
	if(q->fd != -1 && doclose) {
		//D("close: %d",q->fd);
		close(q->fd);
		q->fd = -1;
	}
	
	if(q->lock != NULL)
		UNLOCKR(q->lock);
}


void pqueue_deinit(pqueue_t *q, void (*ptrfree)(void *), int doclose) {
	pqueue_clear(q,ptrfree,doclose);
	if(q->lock != NULL) {
		LOCK_FREE(q->lock);
		xfree(q->lock);
	}
}

void pqueue_free(pqueue_t *q, void (*ptrfree)(void *)) {
	pqueue_deinit(q,ptrfree,1);
	xfree(q);
}

/* internal notification function
 *  - this could block if someone didn't their signal_fd non-blocking
 */
static void q_notify(pqueue_t *q) {
	ssize_t ret;
	if(q->fd != -1) {
		ret = write(q->fd,"\0",1);
		if(ret == -1 && !(errno == EAGAIN)) {
			if(errno == EINTR) {
				/* try again and don't care 
				   about the return value */
				write(q->fd,"\0",1);
			} else {
				/* self error correcting */
				D("close: %d",q->fd);
				close(q->fd);
				q->fd = -1;
			}
		}
	}
}	

void pqueue_push_front(pqueue_t *q, void *ptr) {
	pqueueb_t *p;
	if(q == NULL || ptr == NULL)
		return;
	if(q->lock != NULL)
		LOCKR(q->lock);
	p = q->front;
	q->front = pqueue_bucket_init(ptr);
	q->front->next = p;
	if(q->length == 0)
		q->back = q->front;
	q->length++;
	q_notify(q);
	if(q->lock != NULL)
		UNLOCKR(q->lock);
}

void pqueue_push_back(pqueue_t *q, void *ptr) {
	if(q == NULL || ptr == NULL)
		return;
	if(q->lock != NULL)
		LOCKR(q->lock);
	if(q->back != NULL) {
		q->back->next 	= pqueue_bucket_init(ptr);
		q->back 	= q->back->next;
	} else {
		q->back 	= pqueue_bucket_init(ptr);
		q->front 	= q->back;
	}
	q->length++;
	q_notify(q);
	if(q->lock != NULL)
		UNLOCKR(q->lock);
}

void *pqueue_pop_front(pqueue_t *q) {
	pqueueb_t *p;
	void *ret = NULL;
	if(q == NULL)
		return NULL;
	if(q->lock != NULL)
		LOCKR(q->lock);
	if(q->length > 0) {
		p 	= q->front;
		ret	= q->front->ptr;
		q->front= q->front->next;
		pqueue_bucket_free(p);
		q->length--;
		if(q->length == 0)
			q->back = NULL;
	}
	if(q->lock != NULL)
		UNLOCKR(q->lock);
	return ret;
}

void *pqueue_pop_back(pqueue_t *q) {
	pqueueb_t *p;
	void *ret = NULL;
	if(q == NULL)
		return NULL;
	if(q->lock != NULL)
		LOCKR(q->lock);
	if(q->length > 0) {
		ret	= q->back->ptr;
		pqueue_bucket_free(q->back);
		if(q->length != 1) {
			for(p = q->front; p->next != q->back; p = p->next) ;
			q->back = p;
		} else {
			q->front = NULL;
			q->back = NULL;
		}
		q->length--;
	}
	if(q->lock != NULL)
		UNLOCKR(q->lock);
	return ret;
}

unsigned int pqueue_length(pqueue_t *q) {
	unsigned int ret = 0;
	if(q != NULL) {
		if(q->lock != NULL)
			LOCKR(q->lock);
		ret = q->length;
		if(q->lock != NULL)
			UNLOCKR(q->lock);
	}
	return ret;
}

void pqueue_set_notification_fd(pqueue_t *q, int fd) {
	if(q->lock != NULL)
		LOCKR(q->lock);
	q->fd = fd;
	if(q->lock != NULL)
		UNLOCKR(q->lock);
}