xyuanlu commented on code in PR #2460:
URL: https://github.com/apache/helix/pull/2460#discussion_r1181891116
##########
zookeeper-api/src/main/java/org/apache/helix/zookeeper/zkclient/util/ZkPathRecursiveWatcherTrie.java:
##########
@@ -139,17 +139,88 @@ public void addRecursiveListener(final String path,
RecursivePersistListener lis
if (path.isEmpty()) {
throw new IllegalArgumentException("Empty path: " + path);
}
- final List<String> pathComponents = split(path);
+ final List<String> pathComponents = split(path);
- synchronized(this) {
+ synchronized (this) {
TrieNode parent = _rootNode;
for (final String part : pathComponents) {
- parent = parent.getChildren().computeIfAbsent(part, (p)-> new
TrieNode(part) );
+ parent = parent.getChildren().computeIfAbsent(part, (p) -> new
TrieNode(part));
}
parent._recursiveListeners.add(listener);
}
}
+ public Set<RecursivePersistListener> getAllRecursiveListeners(String path) {
+ Objects.requireNonNull(path, "Path cannot be null");
+
+ final List<String> pathComponents = split(path);
+ Set<RecursivePersistListener> result = new HashSet<>();
+ synchronized (this) {
+ TrieNode cur = _rootNode;
+ for (final String element : pathComponents) {
+ cur = cur.getChild(element);
+ if (cur == null) {
+ break;
+ }
+ result.addAll(cur.getRecursiveListeners());
+ }
+ }
+
+ return result;
+ }
+
+ /**
+ * Removing a RecursivePersistWatcherListener on a path.
+ *
+ * Delete a path from the nearest trie node to current node if this is the
only listener and there
+ * is no child on the trie node.
+ *
+ * @param path the of the lister registered
+ * @param listener the RecursivePersistListener to be removed
+ */
+ public void removeRecursiveListener(final String path,
RecursivePersistListener listener) {
+ Objects.requireNonNull(path, "Path cannot be null");
+
+ if (path.length() == 0) {
+ throw new IllegalArgumentException("Invalid path: " + path);
+ }
+ final List<String> pathComponents = split(path);
+
+ synchronized (this) {
+ TrieNode cur = _rootNode;
+ TrieNode highestNodeForDelete =
+ null; // track the highest node that from that node to leaf node.
+ TrieNode prevDeletable = _rootNode;
+ for (final String part : pathComponents) {
+ cur = cur.getChild(part);
+ if (cur == null) {
+ return;
+ }
+
+ boolean candidateToDelete =
+ (cur.getChildren().size() == 1 &&
cur.getRecursiveListeners().size() == 0) || (
+ cur.getChildren().size() == 0 &&
cur.getRecursiveListeners().size() == 1 && cur
+ .getRecursiveListeners().contains(listener));
+ if (candidateToDelete) {
+ if (highestNodeForDelete == null) {
+ highestNodeForDelete = cur;
+ }
+ } else {
+ prevDeletable = cur;
+ highestNodeForDelete = null;
+ }
+ }
+ if (!cur.getRecursiveListeners().contains(listener)) {
+ return;
+ }
+ cur.getRecursiveListeners().remove(listener);
+
+ if (highestNodeForDelete != null) {
+ prevDeletable.getChildren().remove(highestNodeForDelete.getValue());
+ }
Review Comment:
Had an offline discussion. This block of code notifies 3 TrieNode in each
loop, while the previous block need one TrieNode as input. It is more readable
to keep them separate.
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