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/* Copyright (c) 2019-2021, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file congestion_control_common.h
* \brief Public APIs for congestion control
**/
#ifndef TOR_CONGESTION_CONTROL_COMMON_H
#define TOR_CONGESTION_CONTROL_COMMON_H
#include "core/or/crypt_path_st.h"
#include "core/or/circuit_st.h"
typedef struct congestion_control_t congestion_control_t;
/** Wrapper for the free function, set the CC pointer to NULL after free */
#define congestion_control_free(cc) \
FREE_AND_NULL(congestion_control_t, congestion_control_free_, cc)
void congestion_control_free_(congestion_control_t *cc);
congestion_control_t *congestion_control_new(void);
int congestion_control_dispatch_cc_alg(congestion_control_t *cc,
const circuit_t *circ,
const crypt_path_t *layer_hint);
void congestion_control_note_cell_sent(congestion_control_t *cc,
const circuit_t *circ,
const crypt_path_t *cpath);
bool congestion_control_update_circuit_estimates(congestion_control_t *,
const circuit_t *,
const crypt_path_t *);
int congestion_control_get_package_window(const circuit_t *,
const crypt_path_t *);
int sendme_get_inc_count(const circuit_t *, const crypt_path_t *);
bool circuit_sent_cell_for_sendme(const circuit_t *, const crypt_path_t *);
bool is_monotime_clock_reliable(void);
void congestion_control_new_consensus_params(const networkstatus_t *ns);
/* Ugh, C.. these four are private. Use the getter instead, when
* external to the congestion control code. */
extern uint32_t or_conn_highwater;
extern uint32_t or_conn_lowwater;
extern int32_t cell_queue_high;
extern int32_t cell_queue_low;
/** Stop writing on an orconn when its outbuf is this large */
static inline uint32_t
or_conn_highwatermark(void)
{
return or_conn_highwater;
}
/** Resume writing on an orconn when its outbuf is less than this */
static inline uint32_t
or_conn_lowwatermark(void)
{
return or_conn_lowwater;
}
/** Stop reading on edge connections when we have this many cells
* waiting on the appropriate queue. */
static inline int32_t
cell_queue_highwatermark(void)
{
return cell_queue_high;
}
/** Start reading from edge connections again when we get down to this many
* cells. */
static inline int32_t
cell_queue_lowwatermark(void)
{
return cell_queue_low;
}
/**
* Compute an N-count EWMA, aka N-EWMA. N-EWMA is defined as:
* EWMA = alpha*value + (1-alpha)*EWMA_prev
* with alpha = 2/(N+1).
*
* This works out to:
* EWMA = value*2/(N+1) + EMA_prev*(N-1)/(N+1)
* = (value*2 + EWMA_prev*(N-1))/(N+1)
*/
static inline uint64_t
n_count_ewma(uint64_t curr, uint64_t prev, uint64_t N)
{
if (prev == 0)
return curr;
else
return (2*curr + (N-1)*prev)/(N+1);
}
/* Private section starts. */
#ifdef TOR_CONGESTION_CONTROL_PRIVATE
/*
* Unit tests declaractions.
*/
#ifdef TOR_UNIT_TESTS
#endif /* defined(TOR_UNIT_TESTS) */
#endif /* defined(TOR_CONGESTION_CONTROL_PRIVATE) */
#endif /* !defined(TOR_CONGESTION_CONTROL_COMMON_H) */
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