[tor-commits] [tor] 02/10: Add conflux logs to diagnose cases where RTTs are absent/zero.

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dgoulet pushed a commit to branch main
in repository tor.

commit 176f0929bb3c8ffe2765fc47a24ee44a66ffd217
Author: Mike Perry <mikeperry-git@xxxxxxxxxxxxxx>
AuthorDate: Thu Mar 30 23:43:34 2023 +0000

    Add conflux logs to diagnose cases where RTTs are absent/zero.
---
 src/core/or/conflux.c      |  8 +++++++-
 src/core/or/conflux_pool.c | 50 ++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 51 insertions(+), 7 deletions(-)

diff --git a/src/core/or/conflux.c b/src/core/or/conflux.c
index 5f6af9268b..3330de81ba 100644
--- a/src/core/or/conflux.c
+++ b/src/core/or/conflux.c
@@ -21,6 +21,7 @@
 #include "core/or/conflux.h"
 #include "core/or/conflux_params.h"
 #include "core/or/conflux_util.h"
+#include "core/or/conflux_pool.h"
 #include "core/or/conflux_st.h"
 #include "core/or/conflux_cell.h"
 #include "lib/time/compat_time.h"
@@ -548,11 +549,16 @@ conflux_pick_first_leg(conflux_t *cfx)
     }
   } CONFLUX_FOR_EACH_LEG_END(leg);
 
-  if (BUG(!min_leg)) {
+  if (!min_leg) {
     // Get the 0th leg; if it does not exist, assert
     tor_assert(smartlist_len(cfx->legs) > 0);
     min_leg = smartlist_get(cfx->legs, 0);
     tor_assert(min_leg);
+    if (BUG(min_leg->linked_sent_usec == 0)) {
+      log_warn(LD_BUG, "Conflux has no legs with non-zero RTT. "
+               "Using first leg.");
+      conflux_log_set(cfx, CIRCUIT_IS_ORIGIN(min_leg->circ));
+    }
   }
 
   // TODO-329-TUNING: We may want to initialize this to a cwnd, to
diff --git a/src/core/or/conflux_pool.c b/src/core/or/conflux_pool.c
index 53985df810..7e38e151a8 100644
--- a/src/core/or/conflux_pool.c
+++ b/src/core/or/conflux_pool.c
@@ -822,10 +822,29 @@ record_rtt_client(const circuit_t *circ)
   tor_assert(CIRCUIT_IS_ORIGIN(circ));
 
   leg_t *leg = unlinked_leg_find(circ, true);
-  if (leg && leg->link_sent_usec > 0) {
-    leg->rtt_usec = monotime_absolute_usec() - leg->link_sent_usec;
-    return leg->rtt_usec;
+
+  if (BUG(!leg || leg->link_sent_usec == 0)) {
+    log_warn(LD_BUG,
+             "Conflux: Trying to record client RTT without a timestamp");
+    goto err;
+  }
+
+  uint64_t now = monotime_absolute_usec();
+  tor_assert_nonfatal(now >= leg->link_sent_usec);
+  leg->rtt_usec = now - leg->link_sent_usec;
+  if (leg->rtt_usec == 0) {
+    log_warn(LD_CIRC, "Clock appears stalled for conflux.");
+    // TODO-329-TUNING: For now, let's accept this case. We need to do
+    // tuning and clean up the tests such that they use RTT in order to
+    // fail here.
+    //goto err;
   }
+  return leg->rtt_usec;
+
+ err:
+  // Avoid using this leg until a timestamp comes in
+  if (leg)
+    leg->rtt_usec = UINT64_MAX;
   return UINT64_MAX;
 }
 
@@ -842,10 +861,26 @@ record_rtt_exit(const circuit_t *circ)
   tor_assert(CIRCUIT_IS_ORCIRC(circ));
 
   conflux_leg_t *leg = conflux_get_leg(circ->conflux, circ);
-  if (leg && leg->linked_sent_usec > 0) {
-    leg->circ_rtts_usec = monotime_absolute_usec() - leg->linked_sent_usec;
-    return leg->circ_rtts_usec;
+
+  if (BUG(!leg || leg->linked_sent_usec == 0)) {
+    log_warn(LD_BUG,
+             "Conflux: Trying to record exit RTT without a timestamp");
+    goto err;
   }
+
+  uint64_t now = monotime_absolute_usec();
+  tor_assert_nonfatal(now >= leg->linked_sent_usec);
+  leg->circ_rtts_usec = now - leg->linked_sent_usec;
+
+  if (leg->circ_rtts_usec == 0) {
+    log_warn(LD_CIRC, "Clock appears stalled for conflux.");
+    goto err;
+  }
+  return leg->circ_rtts_usec;
+
+ err:
+  if (leg)
+    leg->circ_rtts_usec = UINT64_MAX;
   return UINT64_MAX;
 }
 
@@ -863,6 +898,9 @@ record_rtt(const circuit_t *circ, bool is_client)
   if (is_client) {
     rtt_usec = record_rtt_client(circ);
 
+    if (rtt_usec == UINT64_MAX)
+      return false;
+
     if (rtt_usec >= get_circuit_build_timeout_ms()*1000) {
       log_info(LD_CIRC, "Conflux leg RTT is above circuit build time out "
                         "currently at %f msec. Relaunching.",

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