Refactor the scaling parameter fetching into a single function.
Also, deprecate the torrc options for the scaling values. It's unlikely anyone but developers will ever tweak them, even if we provided a single ratio value.
This commit is contained in:
Mike Perry
Nick Mathewson
parent
2b2c7f23f5
commit
dfcfb5d17d
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@ -1238,11 +1238,7 @@ The following options are useful only for clients (that is, if
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**PathBiasDropGuards** __NUM__ +
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**PathBiasScaleThreshold** __NUM__ +
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**PathBiasMultFactor** __NUM__ +
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**PathBiasScaleFactor** __NUM__::
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**PathBiasScaleThreshold** __NUM__::
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These options override the default behavior of Tor's (**currently
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experimental**) path bias detection algorithm. To try to find broken or
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misbehaving guard nodes, Tor looks for nodes where more than a certain
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@ -1256,14 +1252,13 @@ The following options are useful only for clients (that is, if
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is set to 1, we disable use of that guard. +
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+
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When we have seen more than PathBiasScaleThreshold
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circuits through a guard, we scale our observations by
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PathBiasMultFactor/PathBiasScaleFactor, so that new observations don't get
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swamped by old ones. +
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circuits through a guard, we scale our observations by 0.5 (governed by
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the consensus) so that new observations don't get swamped by old ones. +
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+
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By default, or if a negative value is provided for one of these options,
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Tor uses reasonable defaults from the networkstatus consensus document.
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If no defaults are available there, these options default to 150, .70,
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.50, .30, 0, 300, 1, and 2 respectively.
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.50, .30, 0, and 300 respectively.
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**PathBiasUseThreshold** __NUM__ +
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@ -1175,38 +1175,31 @@ pathbias_get_scale_threshold(const or_options_t *options)
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}
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/**
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* The scale factor is the denominator for our scaling
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* of circuit counts for our path bias window.
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* Compute the path bias scaling ratio from the consensus
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* parameters pb_multfactor/pb_scalefactor.
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*
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* Note that our use of doubles for the path bias state
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* file means that powers of 2 work best here.
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* Returns a value in (0, 1.0] which we multiply our pathbias
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* counts with to scale them down.
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*/
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static int
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pathbias_get_scale_factor(const or_options_t *options)
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static double
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pathbias_get_scale_ratio(const or_options_t *options)
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{
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#define DFLT_PATH_BIAS_SCALE_FACTOR 2
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if (options->PathBiasScaleFactor >= 1)
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return options->PathBiasScaleFactor;
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else
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return networkstatus_get_param(NULL, "pb_scalefactor",
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DFLT_PATH_BIAS_SCALE_FACTOR, 1, INT32_MAX);
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}
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/**
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* The mult factor is the numerator for our scaling
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* of circuit counts for our path bias window. It
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* allows us to scale by fractions.
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*/
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static int
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pathbias_get_mult_factor(const or_options_t *options)
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{
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#define DFLT_PATH_BIAS_MULT_FACTOR 1
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if (options->PathBiasMultFactor >= 1)
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return options->PathBiasMultFactor;
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else
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return networkstatus_get_param(NULL, "pb_multfactor",
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DFLT_PATH_BIAS_MULT_FACTOR, 1,
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pathbias_get_scale_factor(options));
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/*
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* The scale factor is the denominator for our scaling
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* of circuit counts for our path bias window.
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*
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* Note that our use of doubles for the path bias state
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* file means that powers of 2 work best here.
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*/
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int denominator = networkstatus_get_param(NULL, "pb_scalefactor",
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2, 2, INT32_MAX);
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/**
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* The mult factor is the numerator for our scaling
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* of circuit counts for our path bias window. It
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* allows us to scale by fractions.
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*/
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return networkstatus_get_param(NULL, "pb_multfactor",
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1, 1, denominator)/((double)denominator);
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}
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/** The minimum number of circuit usage attempts before we start
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@ -2301,17 +2294,13 @@ pathbias_check_use_rate(entry_guard_t *guard)
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/* If we get a ton of circuits, just scale everything down */
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if (guard->use_attempts > pathbias_get_scale_use_threshold(options)) {
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const int scale_factor = pathbias_get_scale_factor(options);
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const int mult_factor = pathbias_get_mult_factor(options);
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double scale_ratio = pathbias_get_scale_ratio(options);
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int opened_attempts = pathbias_count_circs_in_states(guard,
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PATH_STATE_USE_ATTEMPTED, PATH_STATE_USE_SUCCEEDED);
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guard->use_attempts -= opened_attempts;
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guard->use_attempts *= mult_factor;
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guard->use_successes *= mult_factor;
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guard->use_attempts /= scale_factor;
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guard->use_successes /= scale_factor;
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guard->use_attempts *= scale_ratio;
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guard->use_successes *= scale_ratio;
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guard->use_attempts += opened_attempts;
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@ -2449,8 +2438,7 @@ pathbias_check_close_rate(entry_guard_t *guard)
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/* If we get a ton of circuits, just scale everything down */
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if (guard->circ_attempts > pathbias_get_scale_threshold(options)) {
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const int scale_factor = pathbias_get_scale_factor(options);
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const int mult_factor = pathbias_get_mult_factor(options);
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double scale_ratio = pathbias_get_scale_ratio(options);
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int opened_attempts = pathbias_count_circs_in_states(guard,
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PATH_STATE_BUILD_ATTEMPTED, PATH_STATE_BUILD_ATTEMPTED);
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int opened_built = pathbias_count_circs_in_states(guard,
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@ -2459,19 +2447,12 @@ pathbias_check_close_rate(entry_guard_t *guard)
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guard->circ_attempts -= opened_attempts;
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guard->circ_successes -= opened_built;
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guard->circ_attempts *= mult_factor;
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guard->circ_successes *= mult_factor;
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guard->timeouts *= mult_factor;
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guard->successful_circuits_closed *= mult_factor;
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guard->collapsed_circuits *= mult_factor;
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guard->unusable_circuits *= mult_factor;
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guard->circ_attempts /= scale_factor;
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guard->circ_successes /= scale_factor;
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guard->timeouts /= scale_factor;
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guard->successful_circuits_closed /= scale_factor;
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guard->collapsed_circuits /= scale_factor;
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guard->unusable_circuits /= scale_factor;
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guard->circ_attempts *= scale_ratio;
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guard->circ_successes *= scale_ratio;
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guard->timeouts *= scale_ratio;
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guard->successful_circuits_closed *= scale_ratio;
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guard->collapsed_circuits *= scale_ratio;
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guard->unusable_circuits *= scale_ratio;
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guard->circ_attempts += opened_attempts;
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guard->circ_successes += opened_built;
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@ -321,8 +321,8 @@ static config_var_t option_vars_[] = {
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V(PathBiasWarnRate, DOUBLE, "-1"),
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V(PathBiasExtremeRate, DOUBLE, "-1"),
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V(PathBiasScaleThreshold, INT, "-1"),
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V(PathBiasScaleFactor, INT, "-1"),
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V(PathBiasMultFactor, INT, "-1"),
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OBSOLETE("PathBiasScaleFactor"),
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OBSOLETE("PathBiasMultFactor"),
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V(PathBiasDropGuards, AUTOBOOL, "0"),
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OBSOLETE("PathBiasUseCloseCounts"),
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@ -3949,8 +3949,6 @@ typedef struct {
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double PathBiasExtremeRate;
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int PathBiasDropGuards;
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int PathBiasScaleThreshold;
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int PathBiasScaleFactor;
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int PathBiasMultFactor;
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/** @} */
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/**
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