[
https://issues.apache.org/jira/browse/SOLR-8323?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15263108#comment-15263108
]
ASF GitHub Bot commented on SOLR-8323:
--------------------------------------
Github user dragonsinth commented on a diff in the pull request:
https://github.com/apache/lucene-solr/pull/32#discussion_r61509699
--- Diff:
solr/solrj/src/java/org/apache/solr/common/cloud/ZkStateReader.java ---
@@ -1066,32 +1079,201 @@ public static String getCollectionPath(String
coll) {
return COLLECTIONS_ZKNODE+"/"+coll + "/state.json";
}
- public void addCollectionWatch(String coll) {
- if (interestingCollections.add(coll)) {
- LOG.info("addZkWatch [{}]", coll);
- new StateWatcher(coll).refreshAndWatch(false);
+ /**
+ * Notify this reader that a local Core is a member of a collection, and
so that collection
+ * state should be watched.
+ *
+ * Not a public API. This method should only be called from
ZkController.
+ *
+ * The number of cores per-collection is tracked, and adding multiple
cores from the same
+ * collection does not increase the number of watches.
+ *
+ * @param collection the collection that the core is a member of
+ *
+ * @see ZkStateReader#unregisterCore(String)
+ */
+ public void registerCore(String collection) {
+ AtomicBoolean reconstructState = new AtomicBoolean(false);
+ collectionWatches.compute(collection, (k, v) -> {
+ if (v == null) {
+ reconstructState.set(true);
+ v = new CollectionWatch();
+ }
+ v.coreRefCount++;
+ return v;
+ });
+ if (reconstructState.get()) {
+ new StateWatcher(collection).refreshAndWatch();
+ synchronized (getUpdateLock()) {
+ constructState();
+ }
+ }
+ }
+
+ /**
+ * Notify this reader that a local core that is a member of a collection
has been closed.
+ *
+ * Not a public API. This method should only be called from
ZkController.
+ *
+ * If no cores are registered for a collection, and there are no {@link
CollectionStateWatcher}s
+ * for that collection either, the collection watch will be removed.
+ *
+ * @param collection the collection that the core belongs to
+ */
+ public void unregisterCore(String collection) {
+ AtomicBoolean reconstructState = new AtomicBoolean(false);
+ collectionWatches.compute(collection, (k, v) -> {
+ if (v == null)
+ return null;
+ if (v.coreRefCount > 0)
+ v.coreRefCount--;
+ if (v.canBeRemoved()) {
+ watchedCollectionStates.remove(collection);
+ lazyCollectionStates.put(collection, new
LazyCollectionRef(collection));
+ reconstructState.set(true);
+ return null;
+ }
+ return v;
+ });
+ if (reconstructState.get()) {
+ synchronized (getUpdateLock()) {
+ constructState();
+ }
+ }
+ }
+
+ /**
+ * Register a CollectionStateWatcher to be called when the state of a
collection changes
+ *
+ * A given CollectionStateWatcher will be only called once. If you want
to have a persistent watcher,
+ * it should register itself again in its {@link
CollectionStateWatcher#onStateChanged(Set, DocCollection)}
+ * method.
+ */
+ public void registerCollectionStateWatcher(String collection,
CollectionStateWatcher stateWatcher) {
+ AtomicBoolean watchSet = new AtomicBoolean(false);
+ collectionWatches.compute(collection, (k, v) -> {
+ if (v == null) {
+ v = new CollectionWatch();
+ watchSet.set(true);
+ }
+ v.stateWatchers.add(stateWatcher);
+ return v;
+ });
+ if (watchSet.get()) {
+ new StateWatcher(collection).refreshAndWatch();
synchronized (getUpdateLock()) {
constructState();
}
}
}
+ /**
+ * Block until a CollectionStatePredicate returns true, or the wait
times out
+ *
+ * Note that the predicate may be called again even after it has
returned true, so
+ * implementors should avoid changing state within the predicate call
itself.
--- End diff --
I think we could tighten this code up to ensure that predicate never gets
call concurrently from two different threads at the same time, this would
simplify things for clients and handle the case of calling it twice when it
succeeds immediately.
> Add CollectionWatcher API to ZkStateReader
> ------------------------------------------
>
> Key: SOLR-8323
> URL: https://issues.apache.org/jira/browse/SOLR-8323
> Project: Solr
> Issue Type: Improvement
> Affects Versions: master
> Reporter: Alan Woodward
> Assignee: Alan Woodward
> Attachments: SOLR-8323.patch, SOLR-8323.patch, SOLR-8323.patch,
> SOLR-8323.patch
>
>
> An API to watch for changes to collection state would be a generally useful
> thing, both internally and for client use.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org
For additional commands, e-mail: dev-h...@lucene.apache.org
