ctubbsii commented on code in PR #5145:
URL: https://github.com/apache/accumulo/pull/5145#discussion_r1873694440
##########
core/src/main/java/org/apache/accumulo/core/fate/zookeeper/ServiceLock.java:
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@@ -762,4 +762,26 @@ public static boolean deleteLock(ZooReaderWriter zk,
ServiceLockPath path, Strin
return false;
}
+
+ /**
+ * Checks that the lock still exists in ZooKeeper. The typical mechanism for
determining if a lock
+ * is lost depends on a Watcher set on the lock node. There exists a case
where the Watcher may
+ * not get called if another Watcher is stuck waiting on I/O or otherwise
hung. In the case where
+ * this method returns false, then the typical action is to exit the server
process.
+ *
+ * @return true if lock path still exists, false otherwise and on error
+ */
+ public boolean verifyLockAtSource() {
+ if (getLockPath() == null) {
+ // lock not set yet
+ return false;
+ }
+ try {
+ return null != this.zooKeeper.exists(getLockPath(), false);
+ } catch (KeeperException | InterruptedException e) {
Review Comment:
If you're worried about RuntimeExceptions, it's better to write it more
carefully as:
```suggestion
} catch (KeeperException | InterruptedException | RuntimeException e) {
```
That way, it isn't written so broadly as to fail to catch an unanticipated
change that introduces a new unhandled checked exception.
However, NPE, specifically isn't possible here, since there's a
requiresNonNull on the ZK that's passed in, and I don't think getLockPath() can
throw that either.
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