xyuanlu commented on code in PR #2376:
URL: https://github.com/apache/helix/pull/2376#discussion_r1106203203
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meta-client/src/main/java/org/apache/helix/metaclient/api/MetaClientInterface.java:
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@@ -378,61 +379,105 @@ void asyncCreate(final String key, final T data, final
EntryMode mode,
/**
* Subscribe change of a particular entry. Including entry data change,
entry deletion and creation
* of the given key.
+ * The listener should be permanent until it's unsubscribed.
* @param key Key to identify the entry
* @param listener An implementation of DataChangeListener
* @see org.apache.helix.metaclient.api.DataChangeListener
* @param skipWatchingNonExistNode Will not register lister to an non-exist
key if set to true.
* Please set to false if you are expecting
ENTRY_CREATED type.
- * @param persistListener The listener will persist when set to true.
Otherwise it will be a one
- * time triggered listener.
* @return Return an boolean indication if subscribe succeeded.
*/
- boolean subscribeDataChange(String key, DataChangeListener listener,
- boolean skipWatchingNonExistNode, boolean persistListener);
+ boolean subscribeDataChange(String key, DataChangeListener listener, boolean
skipWatchingNonExistNode);
+
+ /**
+ * Subscribe a one-time change of a particular entry. Including entry data
change, entry deletion and creation
+ * of the given key.
+ * The implementation should use at-most-once delivery semantic.
+ * @param key Key to identify the entry
+ * @param listener An implementation of DataChangeListener
+ * @see org.apache.helix.metaclient.api.DataChangeListener
+ * @param skipWatchingNonExistNode Will not register lister to an non-exist
key if set to true.
+ * Please set to false if you are expecting
ENTRY_CREATED type.
+ * @return Return an boolean indication if subscribe succeeded.
+ */
+ default boolean subscribeOneTimeDataChange(String key, DataChangeListener
listener,
+ boolean skipWatchingNonExistNode) {
+ throw new NotImplementedException("subscribeOneTimeDataChange is not
implemented");
+ }
/**
* Subscribe for direct child change event on a particular key. It includes
new child
* creation or deletion. It does not include existing child data change.
+ * The listener should be permanent until it's unsubscribed.
* For hierarchy key spaces like zookeeper, it refers to an entry's direct
children nodes.
* For flat key spaces, it refers to keys that matches `prefix*separator`.
* @param key key to identify the entry.
* @param listener An implementation of DirectSubEntryChangeListener.
* @see
org.apache.helix.metaclient.api.DirectChildChangeListener
* @param skipWatchingNonExistNode If the passed in key does not exist, no
listener wil be registered.
- * @param persistListener The listener will persist when set to true.
Otherwise it will be a one
- * time triggered listener.
*
* @return Return an DirectSubEntrySubscribeResult. It will contain a list
of direct sub children if
* subscribe succeeded.
*/
DirectChildSubscribeResult subscribeDirectChildChange(String key,
- DirectChildChangeListener listener, boolean skipWatchingNonExistNode,
- boolean persistListener);
+ DirectChildChangeListener listener, boolean skipWatchingNonExistNode);
+
+ /**
+ * Subscribe for a one-time direct child change event on a particular key.
It includes new child
+ * creation or deletion. It does not include existing child data change.
+ * The implementation should use at-most-once delivery semantic.
+ * For hierarchy key spaces like zookeeper, it refers to an entry's direct
children nodes.
+ * For flat key spaces, it refers to keys that matches `prefix*separator`.
+ *
+ * @param key key to identify the entry.
+ * @param listener An implementation of DirectSubEntryChangeListener.
+ * @see
org.apache.helix.metaclient.api.DirectChildChangeListener
+ * @param skipWatchingNonExistNode If the passed in key does not exist, no
listener wil be registered.
+ *
+ * @return Return an DirectSubEntrySubscribeResult. It will contain a list
of direct sub children if
+ * subscribe succeeded.
+ */
+ default DirectChildSubscribeResult subscribeOneTimeDirectChildChange(String
key,
+ DirectChildChangeListener listener, boolean skipWatchingNonExistNode) {
+ throw new NotImplementedException("subscribeOneTimeDirectChildChange is
not implemented");
+ }
/**
* Subscribe for connection state change.
+ * The listener should be permanent until it's unsubscribed.
* @param listener An implementation of ConnectStateChangeListener.
* @see
org.apache.helix.metaclient.api.ConnectStateChangeListener
- * @param persistListener The listener will persist when set to true.
Otherwise it will be a one
- * time triggered listener.
*
* @return Return an boolean indication if subscribe succeeded.
*/
- boolean subscribeStateChanges(ConnectStateChangeListener listener, boolean
persistListener);
+ boolean subscribeStateChanges(ConnectStateChangeListener listener);
/**
* Subscribe change for all children including entry change and data change.
+ * The listener should be permanent until it's unsubscribed.
+ * For hierarchy key spaces like zookeeper, it would watch the whole tree
structure.
+ * For flat key spaces, it would watch for keys with certain prefix.
+ * @param key key to identify the entry.
+ * @param listener An implementation of ChildChangeListener.
+ * @see org.apache.helix.metaclient.api.ChildChangeListener
+ * @param skipWatchingNonExistNode If the passed in key does not exist, no
listener wil be registered.
+ */
+ boolean subscribeChildChanges(String key, ChildChangeListener listener,
boolean skipWatchingNonExistNode);
Review Comment:
Should we mention `permanent listener` in function name?
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