swamirishi commented on code in PR #5934:
URL: https://github.com/apache/ozone/pull/5934#discussion_r1446502413
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hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/snapshot/SnapshotCache.java:
##########
@@ -304,30 +305,35 @@ private void cleanupInternal() {
OmSnapshot omSnapshot = (OmSnapshot) rcOmSnapshot.get();
LOG.debug("Evicting OmSnapshot instance {} with table key {}",
rcOmSnapshot, omSnapshot.getSnapshotTableKey());
- // Sanity check
- Preconditions.checkState(rcOmSnapshot.getTotalRefCount() == 0L,
- "Illegal state: OmSnapshot reference count non-zero ("
- + rcOmSnapshot.getTotalRefCount() + ") but shows up in the "
- + "clean up list");
final String key = omSnapshot.getSnapshotTableKey();
- final ReferenceCounted<IOmMetadataReader, SnapshotCache> result =
- dbMap.remove(key);
- // Sanity check
- Preconditions.checkState(rcOmSnapshot == result,
- "Cache map entry removal failure. The cache is in an inconsistent "
- + "state. Expected OmSnapshot instance: " + rcOmSnapshot
- + ", actual: " + result + " for key: " + key);
-
- pendingEvictionList.remove(result);
+ dbMap.compute(key, (k, v) -> {
+ if (v == null) {
+ throw new IllegalStateException("Key '" + k + "' does not exist in
cache. The RocksDB " +
+ "instance of the Snapshot may not be closed properly.");
+ }
- // Close the instance, which also closes its DB handle.
- try {
- ((OmSnapshot) rcOmSnapshot.get()).close();
- } catch (IOException ex) {
- throw new IllegalStateException("Error while closing snapshot DB", ex);
- }
+ // Sanity check
+ Preconditions.checkState(rcOmSnapshot == v,
+ "Cache map entry removal failure. The cache is in an inconsistent "
+ + "state. Expected OmSnapshot instance: " + rcOmSnapshot
+ + ", actual: " + v + " for key: " + key);
+
+ // Close the instance, which also closes its DB handle.
+ if (rcOmSnapshot.getTotalRefCount() == 0L) {
Review Comment:
This particular check is not exactly thread safe there would still be a race
condition, this doesn't really take a ref count lock. We should probably put
this function check inside ReferenceCounted class which would take a ref count
lock when doing the check. Some function like
`boolean isTotalRefCountEqual(long expectedValue)` which would return if the
value is equal by taking a ref count lock. You can refer incrementRefCount
function for this.
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