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_
27 #define _RATELIM_INTERNAL_H_
28
29 #ifdef __cplusplus
30 extern "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 */
38 struct 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. */
48 struct 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'. */
68 int 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. */
74 ev_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 */
82 int 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
87 int 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