Tor  0.4.5.0-alpha-dev
circuitmux_ewma.h
Go to the documentation of this file.
1 /* * Copyright (c) 2012-2020, 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 {
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 {
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);
135 
136 #endif /* defined(CIRCUITMUX_EWMA_PRIVATE) */
137 
138 #endif /* !defined(TOR_CIRCUITMUX_EWMA_H) */
DOWNCAST
#define DOWNCAST(to, ptr)
Definition: or.h:109
cmux_ewma_set_options
void cmux_ewma_set_options(const or_options_t *options, const networkstatus_t *consensus)
Definition: circuitmux_ewma.c:597
circuitmux.h
Header file for circuitmux.c.
cell_ewma_initialize_ticks
STATIC void cell_ewma_initialize_ticks(void)
Definition: circuitmux_ewma.c:505
circuit_t
Definition: circuit_st.h:61
circuitmux_policy_circ_data_t
Definition: circuitmux.h:79
circuitmux_ewma_free_all
void circuitmux_ewma_free_all(void)
Definition: circuitmux_ewma.c:719
cell_ewma_get_current_tick_and_fraction
STATIC unsigned cell_ewma_get_current_tick_and_fraction(double *remainder_out)
Definition: circuitmux_ewma.c:521
circuitmux_policy_data_t
Definition: circuitmux.h:70
circuitmux_policy_t
Definition: circuitmux.h:19
or_options_t
Definition: or_options_st.h:45
STATIC
#define STATIC
Definition: testsupport.h:32
networkstatus_t
Definition: networkstatus_st.h:26
smartlist_t
Definition: smartlist_core.h:26
or.h
Master header file for Tor-specific functionality.