tor

The Tor anonymity network
git clone https://git.dasho.dev/tor.git
Log | Files | Refs | README | LICENSE

circuitmux_ewma.h (4178B)

      1 /* * Copyright (c) 2012-2021, The Tor Project, Inc. */
      2 /* See LICENSE for licensing information */
      3 
      4 /**
      5 * \file circuitmux_ewma.h
      6 * \brief Header file for circuitmux_ewma.c
      7 **/
      8 
      9 #ifndef TOR_CIRCUITMUX_EWMA_H
     10 #define TOR_CIRCUITMUX_EWMA_H
     11 
     12 #include "core/or/or.h"
     13 #include "core/or/circuitmux.h"
     14 
     15 /* The public EWMA policy callbacks object. */
     16 extern circuitmux_policy_t ewma_policy;
     17 
     18 /* Externally visible EWMA functions */
     19 void cmux_ewma_set_options(const or_options_t *options,
     20                           const networkstatus_t *consensus);
     21 
     22 void circuitmux_ewma_free_all(void);
     23 
     24 #ifdef CIRCUITMUX_EWMA_PRIVATE
     25 
     26 /*** EWMA structures ***/
     27 
     28 typedef struct cell_ewma_t cell_ewma_t;
     29 typedef struct ewma_policy_data_t ewma_policy_data_t;
     30 typedef struct ewma_policy_circ_data_t ewma_policy_circ_data_t;
     31 
     32 /**
     33 * The cell_ewma_t structure keeps track of how many cells a circuit has
     34 * transferred recently.  It keeps an EWMA (exponentially weighted moving
     35 * average) of the number of cells flushed from the circuit queue onto a
     36 * connection in channel_flush_from_first_active_circuit().
     37 */
     38 
     39 struct cell_ewma_t {
     40  /** The last 'tick' at which we recalibrated cell_count.
     41   *
     42   * A cell sent at exactly the start of this tick has weight 1.0. Cells sent
     43   * since the start of this tick have weight greater than 1.0; ones sent
     44   * earlier have less weight. */
     45  unsigned int last_adjusted_tick;
     46  /** The EWMA of the cell count. */
     47  double cell_count;
     48  /** True iff this is the cell count for a circuit's previous
     49   * channel. */
     50  unsigned int is_for_p_chan : 1;
     51  /** The position of the circuit within the OR connection's priority
     52   * queue. */
     53  int heap_index;
     54 };
     55 
     56 struct ewma_policy_data_t {
     57  circuitmux_policy_data_t base_;
     58 
     59  /**
     60   * Priority queue of cell_ewma_t for circuits with queued cells waiting
     61   * for room to free up on the channel that owns this circuitmux.  Kept
     62   * in heap order according to EWMA.  This was formerly in channel_t, and
     63   * in or_connection_t before that.
     64   */
     65  smartlist_t *active_circuit_pqueue;
     66 
     67  /**
     68   * The tick on which the cell_ewma_ts in active_circuit_pqueue last had
     69   * their ewma values rescaled.  This was formerly in channel_t, and in
     70   * or_connection_t before that.
     71   */
     72  unsigned int active_circuit_pqueue_last_recalibrated;
     73 };
     74 
     75 struct ewma_policy_circ_data_t {
     76  circuitmux_policy_circ_data_t base_;
     77 
     78  /**
     79   * The EWMA count for the number of cells flushed from this circuit
     80   * onto this circuitmux.  Used to determine which circuit to flush
     81   * from next.  This was formerly in circuit_t and or_circuit_t.
     82   */
     83  cell_ewma_t cell_ewma;
     84 
     85  /**
     86   * Pointer back to the circuit_t this is for; since we're separating
     87   * out circuit selection policy like this, we can't attach cell_ewma_t
     88   * to the circuit_t any more, so we can't use SUBTYPE_P directly to a
     89   * circuit_t like before; instead get it here.
     90   */
     91  circuit_t *circ;
     92 };
     93 
     94 #define EWMA_POL_DATA_MAGIC 0x2fd8b16aU
     95 #define EWMA_POL_CIRC_DATA_MAGIC 0x761e7747U
     96 
     97 /*** Downcasts for the above types ***/
     98 
     99 /**
    100 * Downcast a circuitmux_policy_data_t to an ewma_policy_data_t and assert
    101 * if the cast is impossible.
    102 */
    103 
    104 static inline ewma_policy_data_t *
    105 TO_EWMA_POL_DATA(circuitmux_policy_data_t *pol)
    106 {
    107  if (!pol) return NULL;
    108  else {
    109    tor_assertf(pol->magic == EWMA_POL_DATA_MAGIC,
    110                "Mismatch: %"PRIu32" != %"PRIu32,
    111                pol->magic, EWMA_POL_DATA_MAGIC);
    112    return DOWNCAST(ewma_policy_data_t, pol);
    113  }
    114 }
    115 
    116 /**
    117 * Downcast a circuitmux_policy_circ_data_t to an ewma_policy_circ_data_t
    118 * and assert if the cast is impossible.
    119 */
    120 
    121 static inline ewma_policy_circ_data_t *
    122 TO_EWMA_POL_CIRC_DATA(circuitmux_policy_circ_data_t *pol)
    123 {
    124  if (!pol) return NULL;
    125  else {
    126    tor_assertf(pol->magic == EWMA_POL_CIRC_DATA_MAGIC,
    127                "Mismatch: %"PRIu32" != %"PRIu32,
    128                pol->magic, EWMA_POL_CIRC_DATA_MAGIC);
    129    return DOWNCAST(ewma_policy_circ_data_t, pol);
    130  }
    131 }
    132 
    133 STATIC unsigned cell_ewma_get_current_tick_and_fraction(double *remainder_out);
    134 STATIC void cell_ewma_initialize_ticks(void);
    135 
    136 #endif /* defined(CIRCUITMUX_EWMA_PRIVATE) */
    137 
    138 #endif /* !defined(TOR_CIRCUITMUX_EWMA_H) */