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147 lines
3.4 KiB
C
147 lines
3.4 KiB
C
/*
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* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* See the COPYRIGHT file distributed with this work for additional
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* information regarding copyright ownership.
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*/
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#ifndef ISC_RATELIMITER_H
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#define ISC_RATELIMITER_H 1
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/*****
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***** Module Info
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*****/
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/*! \file isc/ratelimiter.h
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* \brief A rate limiter is a mechanism for dispatching events at a limited
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* rate. This is intended to be used when sending zone maintenance
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* SOA queries, NOTIFY messages, etc.
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*/
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/***
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*** Imports.
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***/
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#include <inttypes.h>
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#include <stdbool.h>
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#include <isc/lang.h>
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#include <isc/types.h>
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ISC_LANG_BEGINDECLS
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/*****
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***** Functions.
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*****/
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isc_result_t
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isc_ratelimiter_create(isc_mem_t *mctx, isc_timermgr_t *timermgr,
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isc_task_t *task, isc_ratelimiter_t **ratelimiterp);
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/*%<
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* Create a rate limiter. The execution interval is initially undefined.
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*/
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isc_result_t
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isc_ratelimiter_setinterval(isc_ratelimiter_t *rl, isc_interval_t *interval);
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/*!<
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* Set the minimum interval between event executions.
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* The interval value is copied, so the caller need not preserve it.
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*
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* Requires:
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* '*interval' is a nonzero interval.
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*/
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void
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isc_ratelimiter_setpertic(isc_ratelimiter_t *rl, uint32_t perint);
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/*%<
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* Set the number of events processed per interval timer tick.
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* If 'perint' is zero it is treated as 1.
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*/
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void
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isc_ratelimiter_setpushpop(isc_ratelimiter_t *rl, bool pushpop);
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/*%<
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* Set / clear the ratelimiter to from push pop mode rather
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* first in - first out mode (default).
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*/
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isc_result_t
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isc_ratelimiter_enqueue(isc_ratelimiter_t *rl, isc_task_t *task,
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isc_event_t **eventp);
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/*%<
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* Queue an event for rate-limited execution.
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*
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* This is similar
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* to doing an isc_task_send() to the 'task', except that the
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* execution may be delayed to achieve the desired rate of
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* execution.
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*
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* '(*eventp)->ev_sender' is used to hold the task. The caller
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* must ensure that the task exists until the event is delivered.
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*
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* Requires:
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*\li An interval has been set by calling
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* isc_ratelimiter_setinterval().
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*
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*\li 'task' to be non NULL.
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*\li '(*eventp)->ev_sender' to be NULL.
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*/
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isc_result_t
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isc_ratelimiter_dequeue(isc_ratelimiter_t *rl, isc_event_t *event);
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/*
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* Dequeue a event off the ratelimiter queue.
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*
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* Returns:
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* \li ISC_R_NOTFOUND if the event is no longer linked to the rate limiter.
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* \li ISC_R_SUCCESS
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*/
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void
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isc_ratelimiter_shutdown(isc_ratelimiter_t *ratelimiter);
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/*%<
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* Shut down a rate limiter.
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*
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* Ensures:
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*\li All events that have not yet been
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* dispatched to the task are dispatched immediately with
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* the #ISC_EVENTATTR_CANCELED bit set in ev_attributes.
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*
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*\li Further attempts to enqueue events will fail with
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* #ISC_R_SHUTTINGDOWN.
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*
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*\li The rate limiter is no longer attached to its task.
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*/
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void
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isc_ratelimiter_attach(isc_ratelimiter_t *source, isc_ratelimiter_t **target);
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/*%<
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* Attach to a rate limiter.
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*/
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void
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isc_ratelimiter_detach(isc_ratelimiter_t **ratelimiterp);
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/*%<
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* Detach from a rate limiter.
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*/
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isc_result_t
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isc_ratelimiter_stall(isc_ratelimiter_t *rl);
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/*%<
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* Stall event processing.
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*/
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isc_result_t
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isc_ratelimiter_release(isc_ratelimiter_t *rl);
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/*%<
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* Release a stalled rate limiter.
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*/
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ISC_LANG_ENDDECLS
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#endif /* ISC_RATELIMITER_H */
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