bind/lib/isc/quota.c

/*
 * Copyright (C) 2000  Internet Software Consortium.
 * 
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */

#include <isc/assertions.h>
#include <isc/quota.h>
#include <isc/util.h>

isc_result_t
isc_quota_init(isc_quota_t *quota, int max) {
	quota->max = max;
	quota->used = 0;
	return (isc_mutex_init(&quota->lock));
}

void
isc_quota_destroy(isc_quota_t *quota) {
	quota->max = -1;
	quota->used = -1;
	RUNTIME_CHECK(isc_mutex_destroy(&quota->lock) == ISC_R_SUCCESS);
}

isc_result_t
isc_quota_reserve(isc_quota_t *quota) {
	isc_result_t result;
	LOCK(&quota->lock);
	if (quota->used < quota->max) {
		quota->used++;
		result = ISC_R_SUCCESS;
	} else {
		result = ISC_R_QUOTA;
	}
	UNLOCK(&quota->lock);
	return (result);
}

void
isc_quota_release(isc_quota_t *quota) {
	LOCK(&quota->lock);
	INSIST(quota->used > 0);
	quota->used--;
	UNLOCK(&quota->lock);	
}

isc_result_t
isc_quota_attach(isc_quota_t *quota, isc_quota_t **p)
{
	isc_result_t result;
	INSIST(p != NULL && *p == NULL);
	result = isc_quota_reserve(quota);
	if (result != ISC_R_SUCCESS)
		return (result);
	*p = quota;
	return (ISC_R_SUCCESS);
}

void
isc_quota_detach(isc_quota_t **p)
{
	INSIST(p != NULL && *p != NULL);
	isc_quota_release(*p);
	*p = NULL;
}