release/src/router/dnscrypt/src/libevent-modified/ratelim-internal.h

   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