1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
/*
* Copyright (C) Internet Systems Consortium, Inc. ("ISC")
*
* SPDX-License-Identifier: MPL-2.0
*
* 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 https://mozilla.org/MPL/2.0/.
*
* See the COPYRIGHT file distributed with this work for additional
* information regarding copyright ownership.
*/
#pragma once
/*****
***** Module Info
*****/
/*! \file isc/ratelimiter.h
* \brief A rate limiter is a mechanism for dispatching events at a limited
* rate. This is intended to be used when sending zone maintenance
* SOA queries, NOTIFY messages, etc.
*/
/***
*** Imports.
***/
#include <inttypes.h>
#include <stdbool.h>
#include <isc/lang.h>
#include <isc/types.h>
ISC_LANG_BEGINDECLS
/*****
***** Functions.
*****/
isc_result_t
isc_ratelimiter_create(isc_mem_t *mctx, isc_timermgr_t *timermgr,
isc_task_t *task, isc_ratelimiter_t **ratelimiterp);
/*%<
* Create a rate limiter. The execution interval is initially undefined.
*/
isc_result_t
isc_ratelimiter_setinterval(isc_ratelimiter_t *rl, isc_interval_t *interval);
/*!<
* Set the minimum interval between event executions.
* The interval value is copied, so the caller need not preserve it.
*
* Requires:
* '*interval' is a nonzero interval.
*/
void
isc_ratelimiter_setpertic(isc_ratelimiter_t *rl, uint32_t perint);
/*%<
* Set the number of events processed per interval timer tick.
* If 'perint' is zero it is treated as 1.
*/
void
isc_ratelimiter_setpushpop(isc_ratelimiter_t *rl, bool pushpop);
/*%<
* Set / clear the ratelimiter to from push pop mode rather
* first in - first out mode (default).
*/
isc_result_t
isc_ratelimiter_enqueue(isc_ratelimiter_t *rl, isc_task_t *task,
isc_event_t **eventp);
/*%<
* Queue an event for rate-limited execution.
*
* This is similar
* to doing an isc_task_send() to the 'task', except that the
* execution may be delayed to achieve the desired rate of
* execution.
*
* '(*eventp)->ev_sender' is used to hold the task. The caller
* must ensure that the task exists until the event is delivered.
*
* Requires:
*\li An interval has been set by calling
* isc_ratelimiter_setinterval().
*
*\li 'task' to be non NULL.
*\li '(*eventp)->ev_sender' to be NULL.
*/
isc_result_t
isc_ratelimiter_dequeue(isc_ratelimiter_t *rl, isc_event_t *event);
/*
* Dequeue a event off the ratelimiter queue.
*
* Returns:
* \li ISC_R_NOTFOUND if the event is no longer linked to the rate limiter.
* \li ISC_R_SUCCESS
*/
void
isc_ratelimiter_shutdown(isc_ratelimiter_t *ratelimiter);
/*%<
* Shut down a rate limiter.
*
* Ensures:
*\li All events that have not yet been
* dispatched to the task are dispatched immediately with
* the #ISC_EVENTATTR_CANCELED bit set in ev_attributes.
*
*\li Further attempts to enqueue events will fail with
* #ISC_R_SHUTTINGDOWN.
*
*\li The rate limiter is no longer attached to its task.
*/
void
isc_ratelimiter_attach(isc_ratelimiter_t *source, isc_ratelimiter_t **target);
/*%<
* Attach to a rate limiter.
*/
void
isc_ratelimiter_detach(isc_ratelimiter_t **ratelimiterp);
/*%<
* Detach from a rate limiter.
*/
isc_result_t
isc_ratelimiter_stall(isc_ratelimiter_t *rl);
/*%<
* Stall event processing.
*/
isc_result_t
isc_ratelimiter_release(isc_ratelimiter_t *rl);
/*%<
* Release a stalled rate limiter.
*/
ISC_LANG_ENDDECLS
|
