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/* * Copyright (c) 2012-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file circuitmux_ewma.h
* \brief Header file for circuitmux_ewma.c
**/
#ifndef TOR_CIRCUITMUX_EWMA_H
#define TOR_CIRCUITMUX_EWMA_H
#include "core/or/or.h"
#include "core/or/circuitmux.h"
/* The public EWMA policy callbacks object. */
extern circuitmux_policy_t ewma_policy;
/* Externally visible EWMA functions */
void cmux_ewma_set_options(const or_options_t *options,
const networkstatus_t *consensus);
void circuitmux_ewma_free_all(void);
#ifdef CIRCUITMUX_EWMA_PRIVATE
/*** EWMA structures ***/
typedef struct cell_ewma_t cell_ewma_t;
typedef struct ewma_policy_data_t ewma_policy_data_t;
typedef struct ewma_policy_circ_data_t ewma_policy_circ_data_t;
/**
* The cell_ewma_t structure keeps track of how many cells a circuit has
* transferred recently. It keeps an EWMA (exponentially weighted moving
* average) of the number of cells flushed from the circuit queue onto a
* connection in channel_flush_from_first_active_circuit().
*/
struct cell_ewma_t {
/** The last 'tick' at which we recalibrated cell_count.
*
* A cell sent at exactly the start of this tick has weight 1.0. Cells sent
* since the start of this tick have weight greater than 1.0; ones sent
* earlier have less weight. */
unsigned int last_adjusted_tick;
/** The EWMA of the cell count. */
double cell_count;
/** True iff this is the cell count for a circuit's previous
* channel. */
unsigned int is_for_p_chan : 1;
/** The position of the circuit within the OR connection's priority
* queue. */
int heap_index;
};
struct ewma_policy_data_t {
circuitmux_policy_data_t base_;
/**
* Priority queue of cell_ewma_t for circuits with queued cells waiting
* for room to free up on the channel that owns this circuitmux. Kept
* in heap order according to EWMA. This was formerly in channel_t, and
* in or_connection_t before that.
*/
smartlist_t *active_circuit_pqueue;
/**
* The tick on which the cell_ewma_ts in active_circuit_pqueue last had
* their ewma values rescaled. This was formerly in channel_t, and in
* or_connection_t before that.
*/
unsigned int active_circuit_pqueue_last_recalibrated;
};
struct ewma_policy_circ_data_t {
circuitmux_policy_circ_data_t base_;
/**
* The EWMA count for the number of cells flushed from this circuit
* onto this circuitmux. Used to determine which circuit to flush
* from next. This was formerly in circuit_t and or_circuit_t.
*/
cell_ewma_t cell_ewma;
/**
* Pointer back to the circuit_t this is for; since we're separating
* out circuit selection policy like this, we can't attach cell_ewma_t
* to the circuit_t any more, so we can't use SUBTYPE_P directly to a
* circuit_t like before; instead get it here.
*/
circuit_t *circ;
};
#define EWMA_POL_DATA_MAGIC 0x2fd8b16aU
#define EWMA_POL_CIRC_DATA_MAGIC 0x761e7747U
/*** Downcasts for the above types ***/
/**
* Downcast a circuitmux_policy_data_t to an ewma_policy_data_t and assert
* if the cast is impossible.
*/
static inline ewma_policy_data_t *
TO_EWMA_POL_DATA(circuitmux_policy_data_t *pol)
{
if (!pol) return NULL;
else {
tor_assertf(pol->magic == EWMA_POL_DATA_MAGIC,
"Mismatch: %"PRIu32" != %"PRIu32,
pol->magic, EWMA_POL_DATA_MAGIC);
return DOWNCAST(ewma_policy_data_t, pol);
}
}
/**
* Downcast a circuitmux_policy_circ_data_t to an ewma_policy_circ_data_t
* and assert if the cast is impossible.
*/
static inline ewma_policy_circ_data_t *
TO_EWMA_POL_CIRC_DATA(circuitmux_policy_circ_data_t *pol)
{
if (!pol) return NULL;
else {
tor_assertf(pol->magic == EWMA_POL_CIRC_DATA_MAGIC,
"Mismatch: %"PRIu32" != %"PRIu32,
pol->magic, EWMA_POL_CIRC_DATA_MAGIC);
return DOWNCAST(ewma_policy_circ_data_t, pol);
}
}
STATIC unsigned cell_ewma_get_current_tick_and_fraction(double *remainder_out);
STATIC void cell_ewma_initialize_ticks(void);
#endif /* defined(CIRCUITMUX_EWMA_PRIVATE) */
#endif /* !defined(TOR_CIRCUITMUX_EWMA_H) */
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