Add simple data listeners

[mdsal.git] / binding / mdsal-binding-api / src / main / java / org / opendaylight / mdsal / binding / api / DataTreeChangeService.java

diff --git a/binding/mdsal-binding-api/src/main/java/org/opendaylight/mdsal/binding/api/DataTreeChangeService.java b/binding/mdsal-binding-api/src/main/java/org/opendaylight/mdsal/binding/api/DataTreeChangeService.java
index 6558ec8b273f77cc6d4c5dd65ac47abe5fa24f6a..7803e8787677b6929357d36cb2b7ce3366badea0 100644 (file)
--- a/binding/mdsal-binding-api/src/main/java/org/opendaylight/mdsal/binding/api/DataTreeChangeService.java
+++ b/binding/mdsal-binding-api/src/main/java/org/opendaylight/mdsal/binding/api/DataTreeChangeService.java
@@ -9,7 +9,9 @@ package org.opendaylight.mdsal.binding.api;
 
 import org.eclipse.jdt.annotation.NonNull;
 import org.opendaylight.yangtools.concepts.ListenerRegistration;
+import org.opendaylight.yangtools.concepts.Registration;
 import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
 
 /**
  * A {@link BindingService} which allows users to register for changes to a subtree.
@@ -55,4 +57,81 @@ public interface DataTreeChangeService extends BindingService {
      */
     <T extends DataObject, L extends DataTreeChangeListener<T>> @NonNull ListenerRegistration<L>
             registerDataTreeChangeListener(@NonNull DataTreeIdentifier<T> treeId, @NonNull L listener);
+
+    /**
+     * Registers a {@link DataTreeChangeListener} to receive
+     * notifications when data changes under a given path in the conceptual data tree.
+     *
+     * <p>
+     * You are able to register for notifications  for any node or subtree
+     * which can be represented using {@link DataTreeIdentifier}.
+     *
+     * <p>
+     * This method returns a {@link Registration} object. To
+     * "unregister" your listener for changes call the {@link Registration#close()}
+     * method on the returned object.
+     *
+     * <p>
+     * You MUST explicitly unregister your listener when you no longer want to receive
+     * notifications. This is especially true in OSGi environments, where failure to
+     * do so during bundle shutdown can lead to stale listeners being still registered.
+     * @implSpec This method provides {@link DataListenerAdapter} as listener during
+     *      the registration of {@link DataTreeChangeListener}. This would allow users
+     *      to know the last state of data instead of getting details about what changed
+     *      in the entire tree.
+     * @param treeId Data tree identifier of the subtree which should be watched for
+     *            changes.
+     * @param listener Listener instance which is being registered
+     * @return Listener registration object, which may be used to unregister
+     *         your listener using {@link Registration#close()} to stop
+     *         delivery of change events.
+     */
+    default <T extends DataObject> @NonNull Registration registerDataListener(
+            final @NonNull DataTreeIdentifier<T> treeId, final @NonNull DataListener<T> listener) {
+        return registerDataTreeChangeListener(checkNotWildcard(treeId), new DataListenerAdapter<>(listener));
+    }
+
+    /**
+     * Registers a {@link DataTreeChangeListener} to receive
+     * notifications about the last data state when it changes under a given path in the conceptual data
+     * tree.
+     *
+     * <p>
+     * You are able to register for notifications  for any node or subtree
+     * which can be represented using {@link DataTreeIdentifier}.
+     *
+     * <p>
+     * This method returns a {@link Registration} object. To
+     * "unregister" your listener for changes call the {@link Registration#close()}
+     * method on the returned object.
+     *
+     * <p>
+     * You MUST explicitly unregister your listener when you no longer want to receive
+     * notifications. This is especially true in OSGi environments, where failure to
+     * do so during bundle shutdown can lead to stale listeners being still registered.
+     *
+     * @implSpec This method provides {@link DataChangeListenerAdapter} as listener during
+     *      the registration of {@link DataTreeChangeListener}, which provides a comparison
+     *      of before-value and after-value.
+     *
+     * @param treeId Data tree identifier of the subtree which should be watched for
+     *            changes.
+     * @param listener Listener instance which is being registered
+     * @return Listener registration object, which may be used to unregister
+     *         your listener using {@link Registration#close()} to stop
+     *         delivery of change events.
+     */
+    default <T extends DataObject> @NonNull Registration registerDataChangeListener(
+            final @NonNull DataTreeIdentifier<T> treeId, final @NonNull DataChangeListener<T> listener) {
+        return registerDataTreeChangeListener(checkNotWildcard(treeId), new DataChangeListenerAdapter<>(listener));
+    }
+
+    private static <T extends DataObject> @NonNull DataTreeIdentifier<T> checkNotWildcard(
+            final DataTreeIdentifier<T> treeId) {
+        final @NonNull InstanceIdentifier<T> instanceIdentifier = treeId.getRootIdentifier();
+        if (instanceIdentifier.isWildcarded()) {
+            throw new IllegalArgumentException("Cannot register listener for wildcard " + instanceIdentifier);
+        }
+        return treeId;
+    }
 }
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