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Refactor exponential backoff multipliers into macros

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There are only so many times you can type "4".
This commit is contained in:
teor 2017-07-05 01:32:06 +10:00 committed by Nick Mathewson
parent f30d355903
commit 32f0cbc0f6
3 changed files with 16 additions and 4 deletions
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8
src/or/directory.c
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@ -11,6 +11,7 @@
#include "connection.h"
#include "connection_edge.h"
#include "control.h"
#define DIRECTORY_PRIVATE
#include "directory.h"
#include "dirserv.h"
#include "dirvote.h"
@ -3778,7 +3779,8 @@ find_dl_min_and_max_delay(download_status_t *dls, const or_options_t *options,
/** Advance one delay step. The algorithm is to use the previous delay to
* compute an increment, we construct a value uniformly at random between
* delay+1 and (delay*4)+1 (or *3 in test networks).
* delay+1 and (delay*(DIR_DEFAULT_RANDOM_MULTIPLIER+1))+1 (or
* DIR_TEST_NET_RANDOM_MULTIPLIER in test networks).
* We then clamp that value to be no larger than max_delay, and return it.
*
* Requires that delay is less than INT_MAX, and delay is in [0,max_delay].
@ -3798,11 +3800,11 @@ next_random_exponential_delay(int delay, int max_delay)
/* How much are we willing to add to the delay? */
int max_increment;
int multiplier = 3; /* no more than quadruple the previous delay */
int multiplier = DIR_DEFAULT_RANDOM_MULTIPLIER;
if (get_options()->TestingTorNetwork) {
/* Decrease the multiplier in testing networks. This reduces the variance,
* so that bootstrap is more reliable. */
multiplier = 2; /* no more than triple the previous delay */
multiplier = DIR_TEST_NET_RANDOM_MULTIPLIER;
}
if (delay && delay < (INT_MAX-1) / multiplier) {

10
src/or/directory.h
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@ -177,5 +177,15 @@ STATIC int next_random_exponential_delay(int delay, int max_delay);
#endif
#if defined(TOR_UNIT_TESTS) || defined(DIRECTORY_PRIVATE)
/* Used only by directory.c and test_dir.c */
/* no more than quadruple the previous delay (multiplier + 1) */
#define DIR_DEFAULT_RANDOM_MULTIPLIER (3)
/* no more than triple the previous delay */
#define DIR_TEST_NET_RANDOM_MULTIPLIER (2)
#endif
#endif

2
src/test/test_dir.c
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@ -3610,7 +3610,7 @@ download_status_random_backoff_helper(int min_delay, int max_delay)
int increment = -1;
int old_increment = -1;
time_t current_time = time(NULL);
const int exponent = 4;
const int exponent = DIR_DEFAULT_RANDOM_MULTIPLIER + 1;
/* Check the random backoff cases */
do {