hs_pow: Rate limited dequeue

This adds a token bucket ratelimiter on the dequeue side
of hs_pow's priority queue. It adds config options and docs
for those options. (HiddenServicePoWQueueRate/Burst)

I'm testing this as a way to limit the overhead of circuit
creation when we're experiencing a flood of rendezvous requests.

Signed-off-by: Micah Elizabeth Scott <beth@torproject.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/doc/man/tor.1.txt b/doc/man/tor.1.txt
index a62c7c7d82..2ac6a8471c 100644
--- a/doc/man/tor.1.txt
+++ b/doc/man/tor.1.txt
@@ -3099,6 +3099,19 @@ The following options are per onion service:
     entirely when the service is not overloaded.
     (Default: 0)
 
+[[HiddenServicePoWQueueRate]] **HiddenServicePoWQueueRate** __NUM__::
+
+    The sustained rate of rendezvous requests to dispatch per second from
+    the priority queue. Has no effect when proof-of-work is disabled.
+    If this is set to 0 there's no explicit limit and we will process
+    requests as quickly as possible.
+    (Default: 250)
+
+[[HiddenServicePoWQueueBurst]] **HiddenServicePoWQueueBurst** __NUM__::
+
+    The maximum burst size for rendezvous requests handled from the
+    priority queue at once. (Default: 2500)
+
 
 == DIRECTORY AUTHORITY SERVER OPTIONS