commit 38e3f91c6388bc676c0007b009488ffcc2496bc8 Author: teor teor2345@gmail.com Date: Tue Nov 8 16:39:36 2016 +1100

When using exponential backoff in test networks, use a lower exponent

Lower exponents mean that delays do not vary as much. This helps test networks bootstrap consistently.

Bugfix on 20499. --- changes/bug20597 | 5 +++++ src/or/directory.c | 7 ++++++- 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/changes/bug20597 b/changes/bug20597 new file mode 100644 index 0000000..f199b63 --- /dev/null +++ b/changes/bug20597 @@ -0,0 +1,5 @@ + o Minor bugfixes (test networks, exponential backoff): + - When using exponential backoff in test networks, use a lower exponent, + so the delays do not vary as much. This helps test networks bootstrap + consistently. Fixes bug 20597; bugfix on 20499; not in any released + version of tor. diff --git a/src/or/directory.c b/src/or/directory.c index 1f39981..f4fd521 100644 --- a/src/or/directory.c +++ b/src/or/directory.c @@ -3796,7 +3796,12 @@ next_random_exponential_delay(int delay, int max_delay)

/* How much are we willing to add to the delay? */ int max_increment; - const int multiplier = 3; /* no more than quadruple the previous delay */ + int multiplier = 3; /* no more than quadruple the previous delay */ + 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 */ + }

if (delay && delay < (INT_MAX-1) / multiplier) { max_increment = delay * multiplier;