Github user eribeiro commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/632#discussion_r225016431
--- Diff:
zookeeper-server/src/main/java/org/apache/zookeeper/server/DataTree.java ---
@@ -154,6 +160,26 @@
private final ReferenceCountedACLCache aclCache = new
ReferenceCountedACLCache();
+ // The maximum number of tree digests that we will keep in our history
+ public static final int DIGEST_LOG_LIMIT = 1024;
+
+ // Dump digest every 128 txns, in hex it's 80, which will make it
easier
+ // to align and compare between servers.
+ public static final int DIGEST_LOG_INTERVAL = 128;
+
+ // If this is not null, we are actively looking for a target zxid that
we
+ // want to validate the digest for
+ private ZxidDigest digestFromLoadedSnapshot;
+
+ // The digest associated with the highest zxid in the data tree.
+ private volatile ZxidDigest lastProcessedZxidDigest;
+
+ // Will be notified when digest mismatch event triggered.
+ private List<DigestWatcher> digestWatchers = new ArrayList<>();
--- End diff --
Oh, good points. Firstly, one thing is: this list could be made `final`,
right? :)
> We won't have concurrent modification here
So, `public void addDigestWatcher(DigestWatcher digestWatcher)` couldn't
under any circumstances be called while `reportDigestMismatch` executes the
loop at line 1669? Both are public methods, so that motivated me to write the
first observation about this, but I can surely be missing something obvious...
---
