SaketaChalamchala commented on code in PR #9079:
URL: https://github.com/apache/ozone/pull/9079#discussion_r2558399573
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hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/snapshot/SnapshotDiffManager.java:
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@@ -1223,6 +1273,81 @@ Set<String> getDeltaFiles(OmSnapshot fromSnapshot,
toSnapshot.getSnapshotTableKey()));
}
+ /**
+ * Resolve the VersionMeta of the ancestor snapshot (fromSnapshotId)
+ * that the given snapshot (toSnapshot) was built on.
+ * Traverses the snapshot chain backwards using prevSnapId.
+ *
+ * @param toSnapshot the target snapshot.
+ * @param fromSnapshotId UUID of the source snapshot.
+ * @return the resolved VersionMeta of the source that was used to build the
target.
+ */
+ private OmSnapshotLocalData.VersionMeta resolveBaseVersionMeta(
+ OmSnapshotLocalData toSnapshot,
+ UUID fromSnapshotId) throws IOException {
+ OmMetadataManagerImpl metadataManager =
+ (OmMetadataManagerImpl) ozoneManager.getMetadataManager();
+ // Start walking back from the child snapshot
+ OmSnapshotLocalData child = toSnapshot;
+ int numSnapshotsTraversed = 0;
+ while (numSnapshotsTraversed <= maxSnapshotLimit &&
!child.getPreviousSnapshotId().equals(fromSnapshotId)) {
+ UUID parentId = child.getPreviousSnapshotId();
+ // Load the parent snapshot in the chain
+ child = getSnapshotLocalData(
+ getSnapshotInfo(ozoneManager,
+ metadataManager.getSnapshotChainManager(),
+ parentId));
+ numSnapshotsTraversed++;
+ }
+ if (numSnapshotsTraversed > maxSnapshotLimit) {
+ LOG.error("Exceeded the traversal limit of {} while finding the
VersionMeta of the fromSnapshot : {}" +
+ " that the toSnapshot was built on.", maxSnapshotLimit,
fromSnapshotId);
+ return null;
+ }
+ SnapshotInfo snapshotInfo =
+ getSnapshotInfo(ozoneManager,
metadataManager.getSnapshotChainManager(), fromSnapshotId);
+ OmSnapshotLocalData fromSnapshot = getSnapshotLocalData(snapshotInfo);
+ // Get the version that the child was built from
+ OmSnapshotLocalData.VersionMeta childVersionMeta =
child.getVersionSstFileInfos().get(child.getVersion());
+ int versionUsedWhenBuildingChild =
childVersionMeta.getPreviousSnapshotVersion();
+ return
fromSnapshot.getVersionSstFileInfos().get(versionUsedWhenBuildingChild);
+ }
+
+ /**
+ * Calculates the symmetric difference of SST files between two version
metadata.
+ * Returns a list of SST file names that are present in one snapshot but not
in the other,
+ * i.e., the symmetric difference between the two sets of SST files.
+ *
+ * @param fromSnapVersionMeta Version metadata from the first snapshot;
provides the set of SST files for comparison.
+ * @param toSnapVersionMeta Version metadata from the second snapshot;
provides the set of SST files for comparison.
+ * @return List of SST file names that are present in only one of the two
snapshots (symmetric difference).
+ */
+ private List<String> calculateDiffFiles(OmSnapshotLocalData.VersionMeta
fromSnapVersionMeta,
+ OmSnapshotLocalData.VersionMeta
toSnapVersionMeta) {
+ // Extract SST file names from both snapshots
+ Set<String> fromSnapSstFileNames =
fromSnapVersionMeta.getSstFiles().stream()
+ .map(SstFileInfo::getFileName)
+ .collect(Collectors.toSet());
+
+ Set<String> toSnapSstFileNames = toSnapVersionMeta.getSstFiles().stream()
+ .map(SstFileInfo::getFileName)
+ .collect(Collectors.toSet());
+
+ List<String> diffFiles = new ArrayList<>();
+
+ // Files in fromSnapshot but NOT in toSnapshot
+ diffFiles.addAll(fromSnapSstFileNames.stream()
+ .filter(file -> !toSnapSstFileNames.contains(file))
+ .collect(Collectors.toList()));
Review Comment:
Why would we need this filter if `toSnap` is always built from `fromSnap`.
Wouldn't `toSnap = fromSnap + diff`. In that case, `fromSnap` should never
contain SST files that are not in `toSNap` making this filter unnecessary?
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