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diff --git a/lib/isc/include/isc/quota.h b/lib/isc/include/isc/quota.h
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+/*
+ * 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.
+ */
+
+
+#ifndef ISC_QUOTA_H
+#define ISC_QUOTA_H 1
+
+/*****
+ ***** Module Info
+ *****/
+
+/*! \file isc/quota.h
+ *
+ * \brief The isc_quota_t object is a simple helper object for implementing
+ * quotas on things like the number of simultaneous connections to
+ * a server.  It keeps track of the amount of quota in use, and
+ * encapsulates the locking necessary to allow multiple tasks to
+ * share a quota.
+ */
+
+/***
+ *** Imports.
+ ***/
+
+#include <isc/lang.h>
+#include <isc/mutex.h>
+#include <isc/types.h>
+
+/*****
+ ***** Types.
+ *****/
+
+ISC_LANG_BEGINDECLS
+
+/*% isc_quota structure */
+struct isc_quota {
+	isc_mutex_t	lock; /*%< Locked by lock. */
+	int 		max;
+	int 		used;
+	int		soft;
+};
+
+isc_result_t
+isc_quota_init(isc_quota_t *quota, int max);
+/*%<
+ * Initialize a quota object.
+ *
+ * Returns:
+ * 	ISC_R_SUCCESS
+ *	Other error	Lock creation failed.
+ */
+
+void
+isc_quota_destroy(isc_quota_t *quota);
+/*%<
+ * Destroy a quota object.
+ */
+
+void
+isc_quota_soft(isc_quota_t *quota, int soft);
+/*%<
+ * Set a soft quota.
+ */
+
+void
+isc_quota_max(isc_quota_t *quota, int max);
+/*%<
+ * Re-set a maximum quota.
+ */
+
+isc_result_t
+isc_quota_reserve(isc_quota_t *quota);
+/*%<
+ * Attempt to reserve one unit of 'quota'.
+ *
+ * Returns:
+ * \li 	#ISC_R_SUCCESS		Success
+ * \li	#ISC_R_SOFTQUOTA	Success soft quota reached
+ * \li	#ISC_R_QUOTA		Quota is full
+ */
+
+void
+isc_quota_release(isc_quota_t *quota);
+/*%<
+ * Release one unit of quota.
+ */
+
+isc_result_t
+isc_quota_attach(isc_quota_t *quota, isc_quota_t **p);
+/*%<
+ * Like isc_quota_reserve, and also attaches '*p' to the
+ * quota if successful (ISC_R_SUCCESS or ISC_R_SOFTQUOTA).
+ */
+
+void
+isc_quota_detach(isc_quota_t **p);
+/*%<
+ * Like isc_quota_release, and also detaches '*p' from the
+ * quota.
+ */
+
+ISC_LANG_ENDDECLS
+
+#endif /* ISC_QUOTA_H */