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Name Snapshot Data Blobs by UUID (#40652) (#41523)
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* Name Snapshot Data Blobs by UUID

* There is no functional reason why we need incremental naming for these files but
  * As explained in #38941 it is a possible source of corrupting the repository
  * It wastes API calls for the list operation
  * Is just needless complication
* Since we store the exact names of the data blobs in all the metadata anyway, we can make this change without any BwC considerations
  * Even on the worst case scenario of a downgrade the functionality would continue working since the incremental names wouldn't conflict with the uuids and the number parsing for finding the next incremental name suppresses the exception when encountring a non-numeric value after the double underscore prefix
  • Loading branch information
original-brownbear authored Apr 25, 2019
1 parent 31d5a5a commit cd830b5
Showing 1 changed file with 1 addition and 37 deletions.
Original file line number Diff line number Diff line change
Expand Up @@ -1053,41 +1053,6 @@ protected void finalize(final List<SnapshotFiles> snapshots,
}
}

/**
* Generates blob name
*
* @param generation the blob number
* @return the blob name
*/
protected String fileNameFromGeneration(long generation) {
return DATA_BLOB_PREFIX + Long.toString(generation, Character.MAX_RADIX);
}

/**
* Finds the next available blob number
*
* @param blobs list of blobs in the repository
* @return next available blob number
*/
protected long findLatestFileNameGeneration(Map<String, BlobMetaData> blobs) {
long generation = -1;
for (String name : blobs.keySet()) {
if (!name.startsWith(DATA_BLOB_PREFIX)) {
continue;
}
name = canonicalName(name);
try {
long currentGen = Long.parseLong(name.substring(DATA_BLOB_PREFIX.length()), Character.MAX_RADIX);
if (currentGen > generation) {
generation = currentGen;
}
} catch (NumberFormatException e) {
logger.warn("file [{}] does not conform to the '{}' schema", name, DATA_BLOB_PREFIX);
}
}
return generation;
}

/**
* Loads all available snapshots in the repository
*
Expand Down Expand Up @@ -1180,7 +1145,6 @@ public void snapshot(final IndexCommit snapshotIndexCommit) {
throw new IndexShardSnapshotFailedException(shardId, "failed to list blobs", e);
}

long generation = findLatestFileNameGeneration(blobs);
Tuple<BlobStoreIndexShardSnapshots, Integer> tuple = buildBlobStoreIndexShardSnapshots(blobs);
BlobStoreIndexShardSnapshots snapshots = tuple.v1();
int fileListGeneration = tuple.v2();
Expand Down Expand Up @@ -1248,7 +1212,7 @@ public void snapshot(final IndexCommit snapshotIndexCommit) {
indexIncrementalSize += md.length();
// create a new FileInfo
BlobStoreIndexShardSnapshot.FileInfo snapshotFileInfo =
new BlobStoreIndexShardSnapshot.FileInfo(fileNameFromGeneration(++generation), md, chunkSize());
new BlobStoreIndexShardSnapshot.FileInfo(DATA_BLOB_PREFIX + UUIDs.randomBase64UUID(), md, chunkSize());
indexCommitPointFiles.add(snapshotFileInfo);
filesToSnapshot.add(snapshotFileInfo);
} else {
Expand Down

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