commit 5177ab9e4783c1ca9928ac70d19b7daaeacd6b93 Author: Andrea Shepard andrea@persephoneslair.org Date: Tue Jun 12 11:52:38 2012 -0700

Don't track circuit timeout history unless we're actually using adaptive timeouts --- src/or/circuitbuild.c | 166 +++++++++++++++++++++++++++++++++++------------- 1 files changed, 121 insertions(+), 45 deletions(-)

diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index 2ce00e1..2b5cb21 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -432,41 +432,91 @@ void circuit_build_times_new_consensus_params(circuit_build_times_t *cbt, networkstatus_t *ns) { - int32_t num = circuit_build_times_recent_circuit_count(ns); + int32_t num; + + /* + * First check if we're doing adaptive timeouts at all; nothing to + * update if we aren't. + */ + + if (!circuit_build_times_disabled()) { + num = circuit_build_times_recent_circuit_count(ns); + + if (num > 0) { + if (num != cbt->liveness.num_recent_circs) { + int8_t *recent_circs; + log_notice(LD_CIRC, "The Tor Directory Consensus has changed how many " + "circuits we must track to detect network failures from %d " + "to %d.", cbt->liveness.num_recent_circs, num); + + tor_assert(cbt->liveness.timeouts_after_firsthop || + cbt->liveness.num_recent_circs == 0); + + /* + * Technically this is a circular array that we are reallocating + * and memcopying. However, since it only consists of either 1s + * or 0s, and is only used in a statistical test to determine when + * we should discard our history after a sufficient number of 1's + * have been reached, it is fine if order is not preserved or + * elements are lost. + * + * cbtrecentcount should only be changing in cases of severe network + * distress anyway, so memory correctness here is paramount over + * doing acrobatics to preserve the array. + */ + recent_circs = tor_malloc_zero(sizeof(int8_t)*num); + if (cbt->liveness.timeouts_after_firsthop && + cbt->liveness.num_recent_circs > 0) { + memcpy(recent_circs, cbt->liveness.timeouts_after_firsthop, + sizeof(int8_t)*MIN(num, cbt->liveness.num_recent_circs)); + }

- if (num > 0 && num != cbt->liveness.num_recent_circs) { - int8_t *recent_circs; - log_notice(LD_CIRC, "The Tor Directory Consensus has changed how many " - "circuits we must track to detect network failures from %d " - "to %d.", cbt->liveness.num_recent_circs, num); + // Adjust the index if it needs it. + if (num < cbt->liveness.num_recent_circs) { + cbt->liveness.after_firsthop_idx = MIN(num-1, + cbt->liveness.after_firsthop_idx); + }

- tor_assert(cbt->liveness.timeouts_after_firsthop); + tor_free(cbt->liveness.timeouts_after_firsthop); + cbt->liveness.timeouts_after_firsthop = recent_circs; + cbt->liveness.num_recent_circs = num; + } + /* else no change, nothing to do */ + } + else { /* num == 0 */ + /* + * Weird. This probably shouldn't happen, so log a warning, but try + * to do something sensible anyway. + */ + + log_warn(LD_CIRC, + "The cbtrecentcircs consensus parameter came back zero! " + "This disables adaptive timeouts since we can't keep track of " + "any recent circuits."); + + if (cbt->liveness.timeouts_after_firsthop) { + tor_free(cbt->liveness.timeouts_after_firsthop); + cbt->liveness.timeouts_after_firsthop = NULL; + }

+ cbt->liveness.num_recent_circs = num; + } + } + else { /* - * Technically this is a circular array that we are reallocating - * and memcopying. However, since it only consists of either 1s - * or 0s, and is only used in a statistical test to determine when - * we should discard our history after a sufficient number of 1's - * have been reached, it is fine if order is not preserved or - * elements are lost. - * - * cbtrecentcount should only be changing in cases of severe network - * distress anyway, so memory correctness here is paramount over - * doing acrobatics to preserve the array. + * Adaptive timeouts are disabled; this might be because of the + * LearnCircuitBuildTimes config parameter, and hence permanent, or + * the cbtdisabled consensus parameter, so it may be a new condition. + * Treat it like getting num == 0 above and free the circuit history + * if we have any. */ - recent_circs = tor_malloc_zero(sizeof(int8_t)*num); - memcpy(recent_circs, cbt->liveness.timeouts_after_firsthop, - sizeof(int8_t)*MIN(num, cbt->liveness.num_recent_circs)); - - // Adjust the index if it needs it. - if (num < cbt->liveness.num_recent_circs) { - cbt->liveness.after_firsthop_idx = MIN(num-1, - cbt->liveness.after_firsthop_idx); + + if (cbt->liveness.timeouts_after_firsthop) { + tor_free(cbt->liveness.timeouts_after_firsthop); + cbt->liveness.timeouts_after_firsthop = NULL; }

- tor_free(cbt->liveness.timeouts_after_firsthop); - cbt->liveness.timeouts_after_firsthop = recent_circs; - cbt->liveness.num_recent_circs = num; + cbt->liveness.num_recent_circs = 0; } }

@@ -523,10 +573,20 @@ void circuit_build_times_init(circuit_build_times_t *cbt) { memset(cbt, 0, sizeof(*cbt)); - cbt->liveness.num_recent_circs = + /* + * Check if we really are using adaptive timeouts, and don't keep + * track of this stuff if not. + */ + if (!circuit_build_times_disabled()) { + cbt->liveness.num_recent_circs = circuit_build_times_recent_circuit_count(NULL); - cbt->liveness.timeouts_after_firsthop = tor_malloc_zero(sizeof(int8_t)* - cbt->liveness.num_recent_circs); + cbt->liveness.timeouts_after_firsthop = + tor_malloc_zero(sizeof(int8_t)*cbt->liveness.num_recent_circs); + } + else { + cbt->liveness.num_recent_circs = 0; + cbt->liveness.timeouts_after_firsthop = NULL; + } cbt->close_ms = cbt->timeout_ms = circuit_build_times_get_initial_timeout(); control_event_buildtimeout_set(cbt, BUILDTIMEOUT_SET_EVENT_RESET); } @@ -1213,9 +1273,14 @@ circuit_build_times_network_is_live(circuit_build_times_t *cbt) void circuit_build_times_network_circ_success(circuit_build_times_t *cbt) { - cbt->liveness.timeouts_after_firsthop[cbt->liveness.after_firsthop_idx] = 0; - cbt->liveness.after_firsthop_idx++; - cbt->liveness.after_firsthop_idx %= cbt->liveness.num_recent_circs; + /* Check for NULLness because we might not be using adaptive timeouts */ + if (cbt->liveness.timeouts_after_firsthop && + cbt->liveness.num_recent_circs > 0) { + cbt->liveness.timeouts_after_firsthop[cbt->liveness.after_firsthop_idx] + = 0; + cbt->liveness.after_firsthop_idx++; + cbt->liveness.after_firsthop_idx %= cbt->liveness.num_recent_circs; + } }

/** @@ -1230,10 +1295,15 @@ static void circuit_build_times_network_timeout(circuit_build_times_t *cbt, int did_onehop) { - if (did_onehop) { - cbt->liveness.timeouts_after_firsthop[cbt->liveness.after_firsthop_idx]=1; - cbt->liveness.after_firsthop_idx++; - cbt->liveness.after_firsthop_idx %= cbt->liveness.num_recent_circs; + /* Check for NULLness because we might not be using adaptive timeouts */ + if (cbt->liveness.timeouts_after_firsthop && + cbt->liveness.num_recent_circs > 0) { + if (did_onehop) { + cbt->liveness.timeouts_after_firsthop[cbt->liveness.after_firsthop_idx] + = 1; + cbt->liveness.after_firsthop_idx++; + cbt->liveness.after_firsthop_idx %= cbt->liveness.num_recent_circs; + } } }

@@ -1319,10 +1389,13 @@ circuit_build_times_network_check_changed(circuit_build_times_t *cbt) int timeout_count=0; int i;

- /* how many of our recent circuits made it to the first hop but then - * timed out? */ - for (i = 0; i < cbt->liveness.num_recent_circs; i++) { - timeout_count += cbt->liveness.timeouts_after_firsthop[i]; + if (cbt->liveness.timeouts_after_firsthop && + cbt->liveness.num_recent_circs > 0) { + /* how many of our recent circuits made it to the first hop but then + * timed out? */ + for (i = 0; i < cbt->liveness.num_recent_circs; i++) { + timeout_count += cbt->liveness.timeouts_after_firsthop[i]; + } }

/* If 80% of our recent circuits are timing out after the first hop, @@ -1332,9 +1405,12 @@ circuit_build_times_network_check_changed(circuit_build_times_t *cbt) }

circuit_build_times_reset(cbt); - memset(cbt->liveness.timeouts_after_firsthop, 0, - sizeof(*cbt->liveness.timeouts_after_firsthop)* - cbt->liveness.num_recent_circs); + if (cbt->liveness.timeouts_after_firsthop && + cbt->liveness.num_recent_circs > 0) { + memset(cbt->liveness.timeouts_after_firsthop, 0, + sizeof(*cbt->liveness.timeouts_after_firsthop)* + cbt->liveness.num_recent_circs); + } cbt->liveness.after_firsthop_idx = 0;

/* Check to see if this has happened before. If so, double the timeout