ratelim-internal.h revision 290001 
1/*
2 * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 *    notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 *    notice, this list of conditions and the following disclaimer in the
11 *    documentation and/or other materials provided with the distribution.
12 * 3. The name of the author may not be used to endorse or promote products
13 *    derived from this software without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26#ifndef RATELIM_INTERNAL_H_INCLUDED_
27#define RATELIM_INTERNAL_H_INCLUDED_
28
29#ifdef __cplusplus
30extern "C" {
31#endif
32
33#include "event2/util.h"
34
35/** A token bucket is an internal structure that tracks how many bytes we are
36 * currently willing to read or write on a given bufferevent or group of
37 * bufferevents */
38struct ev_token_bucket {
39	/** How many bytes are we willing to read or write right now? These
40	 * values are signed so that we can do "defecit spending" */
41	ev_ssize_t read_limit, write_limit;
42	/** When was this bucket last updated?  Measured in abstract 'ticks'
43	 * relative to the token bucket configuration. */
44	ev_uint32_t last_updated;
45};
46
47/** Configuration info for a token bucket or set of token buckets. */
48struct ev_token_bucket_cfg {
49	/** How many bytes are we willing to read on average per tick? */
50	size_t read_rate;
51	/** How many bytes are we willing to read at most in any one tick? */
52	size_t read_maximum;
53	/** How many bytes are we willing to write on average per tick? */
54	size_t write_rate;
55	/** How many bytes are we willing to write at most in any one tick? */
56	size_t write_maximum;
57
58	/* How long is a tick?  Note that fractions of a millisecond are
59	 * ignored. */
60	struct timeval tick_timeout;
61
62	/* How long is a tick, in milliseconds?  Derived from tick_timeout. */
63	unsigned msec_per_tick;
64};
65
66/** The current tick is 'current_tick': add bytes to 'bucket' as specified in
67 * 'cfg'. */
68int ev_token_bucket_update_(struct ev_token_bucket *bucket,
69    const struct ev_token_bucket_cfg *cfg,
70    ev_uint32_t current_tick);
71
72/** In which tick does 'tv' fall according to 'cfg'?  Note that ticks can
73 * overflow easily; your code needs to handle this. */
74ev_uint32_t ev_token_bucket_get_tick_(const struct timeval *tv,
75    const struct ev_token_bucket_cfg *cfg);
76
77/** Adjust 'bucket' to respect 'cfg', and note that it was last updated in
78 * 'current_tick'.  If 'reinitialize' is true, we are changing the
79 * configuration of 'bucket'; otherwise, we are setting it up for the first
80 * time.
81 */
82int ev_token_bucket_init_(struct ev_token_bucket *bucket,
83    const struct ev_token_bucket_cfg *cfg,
84    ev_uint32_t current_tick,
85    int reinitialize);
86
87int bufferevent_remove_from_rate_limit_group_internal_(struct bufferevent *bev,
88    int unsuspend);
89
90/** Decrease the read limit of 'b' by 'n' bytes */
91#define ev_token_bucket_decrement_read(b,n)	\
92	do {					\
93		(b)->read_limit -= (n);		\
94	} while (0)
95/** Decrease the write limit of 'b' by 'n' bytes */
96#define ev_token_bucket_decrement_write(b,n)	\
97	do {					\
98		(b)->write_limit -= (n);	\
99	} while (0)
100
101#ifdef __cplusplus
102}
103#endif
104
105#endif
106