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      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
    106