external/bsd/libevent/dist/ratelim-internal.h

   1 /*      $NetBSD: ratelim-internal.h,v 1.2 2013/04/11 16:56:41 christos Exp $    */
   2 /*
   3  * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The name of the author may not be used to endorse or promote products
  14  *    derived from this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27 #ifndef _RATELIM_INTERNAL_H_
  28 #define _RATELIM_INTERNAL_H_
  29
  30 #ifdef __cplusplus
  31 extern "C" {
  32 #endif
  33
  34 #include "event2/util.h"
  35
  36 /** A token bucket is an internal structure that tracks how many bytes we are
  37  * currently willing to read or write on a given bufferevent or group of
  38  * bufferevents */
  39 struct ev_token_bucket {
  40         /** How many bytes are we willing to read or write right now? These
  41          * values are signed so that we can do "defecit spending" */
  42         ev_ssize_t read_limit, write_limit;
  43         /** When was this bucket last updated?  Measured in abstract 'ticks'
  44          * relative to the token bucket configuration. */
  45         ev_uint32_t last_updated;
  46 };
  47
  48 /** Configuration info for a token bucket or set of token buckets. */
  49 struct ev_token_bucket_cfg {
  50         /** How many bytes are we willing to read on average per tick? */
  51         size_t read_rate;
  52         /** How many bytes are we willing to read at most in any one tick? */
  53         size_t read_maximum;
  54         /** How many bytes are we willing to write on average per tick? */
  55         size_t write_rate;
  56         /** How many bytes are we willing to write at most in any one tick? */
  57         size_t write_maximum;
  58
  59         /* How long is a tick?  Note that fractions of a millisecond are
  60          * ignored. */
  61         struct timeval tick_timeout;
  62
  63         /* How long is a tick, in milliseconds?  Derived from tick_timeout. */
  64         unsigned msec_per_tick;
  65 };
  66
  67 /** The current tick is 'current_tick': add bytes to 'bucket' as specified in
  68  * 'cfg'. */
  69 int ev_token_bucket_update(struct ev_token_bucket *bucket,
  70     const struct ev_token_bucket_cfg *cfg,
  71     ev_uint32_t current_tick);
  72
  73 /** In which tick does 'tv' fall according to 'cfg'?  Note that ticks can
  74  * overflow easily; your code needs to handle this. */
  75 ev_uint32_t ev_token_bucket_get_tick(const struct timeval *tv,
  76     const struct ev_token_bucket_cfg *cfg);
  77
  78 /** Adjust 'bucket' to respect 'cfg', and note that it was last updated in
  79  * 'current_tick'.  If 'reinitialize' is true, we are changing the
  80  * configuration of 'bucket'; otherwise, we are setting it up for the first
  81  * time.
  82  */
  83 int ev_token_bucket_init(struct ev_token_bucket *bucket,
  84     const struct ev_token_bucket_cfg *cfg,
  85     ev_uint32_t current_tick,
  86     int reinitialize);
  87
  88 int bufferevent_remove_from_rate_limit_group_internal(struct bufferevent *bev,
  89     int unsuspend);
  90
  91 /** Decrease the read limit of 'b' by 'n' bytes */
  92 #define ev_token_bucket_decrement_read(b,n)     \
  93         do {                                    \
  94                 (b)->read_limit -= (n);         \
  95         } while (/*CONSTCOND*/0)
  96 /** Decrease the write limit of 'b' by 'n' bytes */
  97 #define ev_token_bucket_decrement_write(b,n)    \
  98         do {                                    \
  99                 (b)->write_limit -= (n);        \
 100         } while (/*CONSTCOND*/0)
 101
 102 #ifdef __cplusplus
 103 }
 104 #endif
 105
 106 #endif