eolivelli commented on a change in pull request #1106: ZOOKEEPER-1416 -
Persistent, recursive watchers
URL: https://github.com/apache/zookeeper/pull/1106#discussion_r331074728
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File path: zookeeper-server/src/main/java/org/apache/zookeeper/ZooKeeper.java
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@@ -3028,6 +3147,104 @@ public void removeAllWatches(String path, WatcherType
watcherType, boolean local
removeWatches(ZooDefs.OpCode.removeWatches, path, null, watcherType,
local, cb, ctx);
}
+ /**
+ * Modes available to {@link ZooKeeper#addWatch(String, Watcher,
AddWatchMode)}
+ */
+ public enum AddWatchMode {
+ /**
+ * <p>
+ * Set a watcher on the given path that does not get removed when
triggered (i.e. it stays active
+ * until it is removed). This watcher
+ * is triggered for both data and child events. To remove the watcher,
use
+ * <tt>removeWatches()</tt> with <tt>WatcherType.Any</tt>. The watcher
behaves as if you placed an exists() watch and
+ * a getData() watch on the ZNode at the given path.
+ * </p>
+ */
+ PERSISTENT(ZooDefs.AddWatchModes.persistent),
+
+ /**
+ * <p>
+ * Set a watcher on the given path that: a) does not get removed when
triggered (i.e. it stays active
+ * until it is removed); b) applies not only to the registered path
but all child paths recursively. This watcher
+ * is triggered for both data and child events. To remove the watcher,
use
+ * <tt>removeWatches()</tt> with <tt>WatcherType.Any</tt>
+ * </p>
+ *
+ * <p>
+ * The watcher behaves as if you placed an exists() watch and
+ * a getData() watch on the ZNode at the given path
<strong>and</strong> any ZNodes that are children
+ * of the given path including children added later.
+ * </p>
+ *
+ * <p>
+ * NOTE: when there are active recursive watches there is a small
performance decrease as all segments
+ * of ZNode paths must be checked for watch triggering.
+ * </p>
+ */
+ PERSISTENT_RECURSIVE(ZooDefs.AddWatchModes.persistentRecursive)
+ ;
+
+ public int getMode() {
+ return mode;
+ }
+
+ private final int mode;
+
+ AddWatchMode(int mode) {
+ this.mode = mode;
+ }
+ }
+
+ /**
+ * Add a watch to the given znode using the given mode. Note: not all
+ * watch types can be set with this method. Only the modes available
+ * in {@link AddWatchMode} can be set with this method.
+ *
+ * @param basePath the path that the watcher applies to
+ * @param watcher the watcher
+ * @param mode type of watcher to add
+ * @throws InterruptedException If the server transaction is interrupted.
+ * @throws KeeperException If the server signals an error with a non-zero
+ * error code.
+ */
+ public void addWatch(String basePath, Watcher watcher, AddWatchMode mode)
Review comment:
@Randgalt this is perfect to me !
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