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/* Copyright (c) 2003-2004, Roger Dingledine
* Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
* Copyright (c) 2007-2019, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file ratelim.h
* \brief Summarize similar messages that would otherwise flood the logs.
**/
#ifndef TOR_RATELIM_H
#define TOR_RATELIM_H
#include <time.h>
/* Rate-limiter */
/** A ratelim_t remembers how often an event is occurring, and how often
* it's allowed to occur. Typical usage is something like:
*
<pre>
if (possibly_very_frequent_event()) {
const int INTERVAL = 300;
static ratelim_t warning_limit = RATELIM_INIT(INTERVAL);
char *m;
if ((m = rate_limit_log(&warning_limit, approx_time()))) {
log_warn(LD_GENERAL, "The event occurred!%s", m);
tor_free(m);
}
}
</pre>
As a convenience wrapper for logging, you can replace the above with:
<pre>
if (possibly_very_frequent_event()) {
static ratelim_t warning_limit = RATELIM_INIT(300);
log_fn_ratelim(&warning_limit, LOG_WARN, LD_GENERAL,
"The event occurred!");
}
</pre>
*/
typedef struct ratelim_t {
int rate;
time_t last_allowed;
int n_calls_since_last_time;
} ratelim_t;
#define RATELIM_INIT(r) { (r), 0, 0 }
#define RATELIM_TOOMANY (16*1000*1000)
char *rate_limit_log(ratelim_t *lim, time_t now);
#endif
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