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Don't track circuit timeout history unless we're actually using adaptive timeouts

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This commit is contained in:
Andrea Shepard 2012-06-12 11:52:38 -07:00 committed by Nick Mathewson
parent 41a458ece1
commit 5177ab9e47
1 changed files with 120 additions and 44 deletions
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164
src/or/circuitbuild.c
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@ -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;
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);
/*
* First check if we're doing adaptive timeouts at all; nothing to
* update if we aren't.
*/
tor_assert(cbt->liveness.timeouts_after_firsthop);
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));
}
// 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_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