Re: [PR] Bound the ring walk of ParentConsistentHash::selectParent [trafficserver]

["cmcfarlen (via GitHub)" <gi...@apache.org>]

cmcfarlen commented on code in PR #13368:
URL: https://github.com/apache/trafficserver/pull/13368#discussion_r3714815587


##########
src/proxy/ParentConsistentHash.cc:
##########
@@ -151,6 +151,14 @@ ParentConsistentHash::selectParent(bool first_call, ParentResult *result, Reques
   HostStatus                &pStatus   = HostStatus::instance();
   TSHostStatus               host_stat = TSHostStatus::TS_HOST_STATUS_INIT;
 
+  // Bound the all-down ring walk: read each distinct parent's status at most once.
+  // Sized to the pool -- num_parents is not capped at MAX_PARENTS, so a fixed array would overflow.
+  int const         num_parents_in_ring[2] = {result->rec->num_parents, result->rec->num_secondary_parents};
+  std::vector<bool> seen_parent[2]         = {std::vector<bool>(num_parents_in_ring[PRIMARY]),
+                                              std::vector<bool>(num_parents_in_ring[SECONDARY])};

Review Comment:
   I don't like the allocation here.  Consider using ts::LocalBuffer or swoop::Vectray instead to try to avoid heap allocation here.



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