1 files changed, 94 insertions, 0 deletions
diff --git a/lib/isc/quota.c b/lib/isc/quota.c
new file mode 100644
index 0000000..3ddff0d
--- /dev/null
+++ b/lib/isc/quota.c
@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+
+/*! \file */
+
+#include <config.h>
+
+#include <stddef.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;
+	quota->soft = 0;
+	return (isc_mutex_init(&quota->lock));
+}
+
+void
+isc_quota_destroy(isc_quota_t *quota) {
+	INSIST(quota->used == 0);
+	quota->max = 0;
+	quota->used = 0;
+	quota->soft = 0;
+	DESTROYLOCK(&quota->lock);
+}
+
+void
+isc_quota_soft(isc_quota_t *quota, int soft) {
+	LOCK(&quota->lock);
+	quota->soft = soft;
+	UNLOCK(&quota->lock);
+}
+
+void
+isc_quota_max(isc_quota_t *quota, int max) {
+	LOCK(&quota->lock);
+	quota->max = max;
+	UNLOCK(&quota->lock);
+}
+
+isc_result_t
+isc_quota_reserve(isc_quota_t *quota) {
+	isc_result_t result;
+	LOCK(&quota->lock);
+	if (quota->max == 0 || quota->used < quota->max) {
+		if (quota->soft == 0 || quota->used < quota->soft)
+			result = ISC_R_SUCCESS;
+		else
+			result = ISC_R_SOFTQUOTA;
+		quota->used++;
+	} 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 || result == ISC_R_SOFTQUOTA)
+		*p = quota;
+	return (result);
+}
+
+void
+isc_quota_detach(isc_quota_t **p)
+{
+	INSIST(p != NULL && *p != NULL);
+	isc_quota_release(*p);
+	*p = NULL;
+}