dapl_ring_buffer_util.c revision 9e39c5ba00a55fa05777cc94b148296af305e135
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2002-2003, Network Appliance, Inc. All rights reserved.
*/
/*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
*
* MODULE: dapl_ring_buffer_util.c
*
* PURPOSE: Ring buffer management
* Description: Support and management functions for ring buffers
*
* $Id: dapl_ring_buffer_util.c,v 1.9 2003/07/08 14:23:35 sjs2 Exp $
*/
#include "dapl_ring_buffer_util.h"
/*
* dapls_rbuf_alloc
*
* Given a DAPL_RING_BUFFER, initialize it and provide memory for
* the ringbuf itself. A passed in size will be adjusted to the next
* largest power of two number to simplify management.
*
* Input:
* rbuf pointer to DAPL_RING_BUFFER
* size number of elements to allocate & manage
*
* Output:
* none
*
* Returns:
* DAT_SUCCESS
* DAT_INSUFFICIENT_RESOURCES
*
*/
DAT_RETURN
dapls_rbuf_alloc(
INOUT DAPL_RING_BUFFER *rbuf,
IN DAT_COUNT size)
{
unsigned int rsize; /* real size */
/*
* The circular buffer must be allocated one too large.
* This eliminates any need for a distinct counter, as that
* having the two pointers equal always means "empty" -- never "full"
*/
size++;
/* Put size on a power of 2 boundary */
rsize = 1;
while ((DAT_COUNT)rsize < size) {
rsize <<= 1;
}
rbuf->base = (void *) dapl_os_alloc(rsize * sizeof (void *));
if (rbuf->base != NULL) {
rbuf->lim = rsize - 1;
rbuf->head = 0;
rbuf->tail = 0;
dapl_os_lock_init(&rbuf->lock);
} else {
return (DAT_INSUFFICIENT_RESOURCES | DAT_RESOURCE_MEMORY);
}
return (DAT_SUCCESS);
}
/*
* dapls_rbuf_realloc
*
* Resizes an empty DAPL_RING_BUFFER. This function is not thread safe;
* adding or removing elements from a ring buffer while resizing
* will have indeterminate results.
*
* Input:
* rbuf pointer to DAPL_RING_BUFFER
* size number of elements to allocate & manage
*
* Output:
* none
*
* Returns:
* DAT_SUCCESS
* DAT_INVALID_STATE
* DAT_INSUFFICIENT_RESOURCES
*
*/
DAT_RETURN
dapls_rbuf_realloc(
INOUT DAPL_RING_BUFFER *rbuf,
IN DAT_COUNT size)
{
int rsize; /* real size */
DAT_RETURN dat_status;
dat_status = DAT_SUCCESS;
/* if the ring buffer is not empty */
if (rbuf->head != rbuf->tail) {
dat_status = DAT_ERROR(DAT_INVALID_STATE, 0);
goto bail;
}
/* Put size on a power of 2 boundary */
rsize = 1;
while (rsize < size) {
rsize <<= 1;
}
rbuf->base = (void *)dapl_os_realloc(rbuf->base,
rsize * sizeof (void *));
if (NULL == rbuf->base) {
dat_status = DAT_ERROR(DAT_INSUFFICIENT_RESOURCES,
DAT_RESOURCE_MEMORY);
goto bail;
}
rbuf->lim = rsize - 1;
bail:
return (dat_status);
}
/*
* dapls_rbuf_destroy
*
* Release the buffer and reset pointers to a DAPL_RING_BUFFER
*
* Input:
* rbuf pointer to DAPL_RING_BUFFER
*
* Output:
* none
*
* Returns:
* none
*
*/
void
dapls_rbuf_destroy(
IN DAPL_RING_BUFFER *rbuf)
{
if ((NULL == rbuf) ||
(NULL == rbuf->base)) {
return;
}
dapl_os_lock_destroy(&rbuf->lock);
dapl_os_free(rbuf->base, (rbuf->lim + 1) * sizeof (void *));
rbuf->base = NULL;
rbuf->lim = 0;
}
/*
* dapls_rbuf_add
*
* Add an entry to the ring buffer
*
* Input:
* rbuf pointer to DAPL_RING_BUFFER
* entry entry to add
*
* Output:
* none
*
* Returns:
* DAT_SUCCESS
* DAT_INSUFFICIENT_RESOURCES (queue full)
*
*/
DAT_RETURN
dapls_rbuf_add(
IN DAPL_RING_BUFFER *rbuf,
IN void *entry)
{
DAPL_ATOMIC pos;
dapl_os_lock(&rbuf->lock);
pos = rbuf->head;
if (((pos + 1) & rbuf->lim) != rbuf->tail) {
rbuf->base[pos] = entry;
rbuf->head = (pos + 1) & rbuf->lim;
dapl_os_unlock(&rbuf->lock);
return (DAT_SUCCESS);
}
dapl_os_unlock(&rbuf->lock);
return (DAT_ERROR(DAT_INSUFFICIENT_RESOURCES, DAT_RESOURCE_MEMORY));
}
/*
* dapls_rbuf_remove
*
* Remove an entry from the ring buffer
*
* Input:
* rbuf pointer to DAPL_RING_BUFFER
*
* Output:
* entry entry removed from the ring buffer
*
* Returns:
* a pointer to a buffer entry
*/
void *
dapls_rbuf_remove(
IN DAPL_RING_BUFFER *rbuf)
{
DAPL_ATOMIC pos;
dapl_os_lock(&rbuf->lock);
if (rbuf->head != rbuf->tail) {
pos = rbuf->tail;
rbuf->tail = (pos + 1) & rbuf->lim;
dapl_os_unlock(&rbuf->lock);
return (rbuf->base[pos]);
}
dapl_os_unlock(&rbuf->lock);
return (NULL);
}
/*
* dapli_rbuf_count
*
* Return the number of entries in use in the ring buffer
*
* Input:
* rbuf pointer to DAPL_RING_BUFFER
*
* Output:
* none
*
* Returns:
* count of entries
*
*/
DAT_COUNT
dapls_rbuf_count(
IN DAPL_RING_BUFFER *rbuf)
{
int head;
int tail;
dapl_os_lock(&rbuf->lock);
head = rbuf->head;
tail = rbuf->tail;
dapl_os_unlock(&rbuf->lock);
if (head == tail)
return (0);
if (head > tail)
return (head - tail);
/* add 1 to lim as it is a mask, number of entries - 1 */
return ((rbuf->lim + 1 - tail + head));
}