Github user eribeiro commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/632#discussion_r224206365
--- Diff:
zookeeper-server/src/main/java/org/apache/zookeeper/server/DataTree.java ---
@@ -1521,4 +1566,179 @@ public boolean removeWatch(String path, WatcherType
type, Watcher watcher) {
public ReferenceCountedACLCache getReferenceCountedAclCache() {
return aclCache;
}
+
+ /**
+ * Add the digest to the historical list, and update the latest zxid
digest.
+ */
+ private void logZxidDigest(long zxid, long digest) {
+ ZxidDigest zxidDigest = new ZxidDigest(zxid,
DigestCalculator.DIGEST_VERSION, digest);
+ lastProcessedZxidDigest = zxidDigest;
+ if (zxidDigest.zxid % DIGEST_LOG_INTERVAL == 0) {
+ synchronized (digestLog) {
+ digestLog.add(zxidDigest);
+ if (digestLog.size() > DIGEST_LOG_LIMIT) {
+ digestLog.poll();
+ }
+ }
+ }
+ }
+
+ /**
+ * Serializing the digest to snapshot, this is done after the data
tree
+ * is being serialized, so when we replay the txns and it hits this
zxid
+ * we know we should be in a non-fuzzy state, and have the same
digest.
+ *
+ * @param oa the output stream to write to
+ * @return true if the digest is serialized successfully
+ */
+ public boolean serializeZxidDigest(OutputArchive oa) throws
IOException {
+ if (!DigestCalculator.digestEnabled()) {
+ return false;
+ }
+
+ ZxidDigest zxidDigest = lastProcessedZxidDigest;
+ if (zxidDigest == null) {
+ // write an empty digest
+ zxidDigest = new ZxidDigest();
+ }
+ zxidDigest.serialize(oa);
+ return true;
+ }
+
+ /**
+ * Deserializing the zxid digest from the input stream and update the
+ * digestFromLoadedSnapshot.
+ *
+ * @param ia the input stream to read from
+ * @return the true if it deserialized successfully
+ */
+ public boolean deserializeZxidDigest(InputArchive ia) throws
IOException {
+ if (!DigestCalculator.digestEnabled()) {
+ return false;
+ }
+
+ try {
+ ZxidDigest zxidDigest = new ZxidDigest();
+ zxidDigest.deserialize(ia);
+ if (zxidDigest.zxid > 0) {
+ digestFromLoadedSnapshot = zxidDigest;
+ }
+ return true;
--- End diff --
nit: put the `return true;` as the last line in the method. Therefore, this
is the default behavior, and it return false early in case of failure (line
1617 and 1630).
---
