keith-turner commented on a change in pull request #2293:
URL: https://github.com/apache/accumulo/pull/2293#discussion_r733847427
##########
File path:
server/gc/src/main/java/org/apache/accumulo/gc/GarbageCollectionAlgorithm.java
##########
@@ -217,11 +221,43 @@ private void confirmDeletes(GarbageCollectionEnvironment
gce,
throw new RuntimeException(
"Scanner over metadata table returned unexpected column : " +
entry.getKey());
}
+ Set<String> tableIdsAfter = gce.getTableIDs();
+ ensureAllTablesChecked(Collections.unmodifiableSet(tableIdsBefore),
+ Collections.unmodifiableSet(tableIdsSeen),
Collections.unmodifiableSet(tableIdsAfter));
confirmDeletesFromReplication(gce.getReplicationNeededIterator(),
candidateMap.entrySet().iterator());
}
+ @VisibleForTesting
+ /**
+ *
+ */
+ protected void ensureAllTablesChecked(Set<String> tableIdsBefore,
Set<String> tableIdsSeen,
+ Set<String> tableIdsAfter) {
+
+ // if a table was added or deleted during this run, it is acceptable to not
+ // have seen those tables ids when scanning the metadata table. So get the
intersection
+ Set<String> tableIdsMustHaveSeen = new HashSet<>(tableIdsBefore);
+ tableIdsMustHaveSeen.retainAll(tableIdsAfter);
+
+ if (tableIdsMustHaveSeen.isEmpty() && !tableIdsSeen.isEmpty()) {
+ // we saw no table ids in ZK but did in the metadata table. This is
unexpected.
+ throw new RuntimeException(
+ "Saw no table ids in ZK but did see table ids in metadata table: " +
tableIdsSeen);
+ }
+
+ // From that intersection, remove all the table ids that were seen.
+ tableIdsMustHaveSeen.removeAll(tableIdsSeen);
Review comment:
> Maybe in 2.x we need a configurable mode for the GC to handle both use
cases.
We could also explore reducing/removing the ambiguity when trying to discern
between tables being added/removed and some kind of silent error when reading
from ZK. For example maybe for deleting tables we could make the GC remove
table ids (with a certain table state like DELETED) from ZK instead of the
manager. This would allow the GC to positively identify a table that was
deleted while it was scanning the metadata table and know that its ok to see or
not see that table in the metadata table.
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