Line data    Source code

       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         274 : TO_EWMA_POL_DATA(circuitmux_policy_data_t *pol)
     106             : {
     107         274 :   if (!pol) return NULL;
     108             :   else {
     109         274 :     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          59 : TO_EWMA_POL_CIRC_DATA(circuitmux_policy_circ_data_t *pol)
     123             : {
     124          59 :   if (!pol) return NULL;
     125             :   else {
     126          59 :     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) */