BUG-2673: Introduced new more low-level DOM Data Change APIs

[controller.git] / opendaylight / md-sal / sal-dom-api / src / main / java / org / opendaylight / controller / md / sal / dom / api / DOMDataTreeChangeListener.java

diff --git a/opendaylight/md-sal/sal-dom-api/src/main/java/org/opendaylight/controller/md/sal/dom/api/DOMDataTreeChangeListener.java b/opendaylight/md-sal/sal-dom-api/src/main/java/org/opendaylight/controller/md/sal/dom/api/DOMDataTreeChangeListener.java
new file mode 100644 (file)
index 0000000..2578790
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+++ b/opendaylight/md-sal/sal-dom-api/src/main/java/org/opendaylight/controller/md/sal/dom/api/DOMDataTreeChangeListener.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2015 Cisco Systems, Inc. and others.  All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.controller.md.sal.dom.api;
+
+import java.util.Collection;
+import java.util.EventListener;
+import javax.annotation.Nonnull;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidate;
+
+/**
+ * Interface implemented by classes interested in receiving notifications about
+ * data tree changes. This interface differs from {@link DOMDataChangeListener}
+ * in that it provides a cursor-based view of the change, which has potentially
+ * lower overhead.
+ */
+public interface DOMDataTreeChangeListener extends EventListener {
+    /**
+     * Invoked when there was data change for the supplied path, which was used
+     * to register this listener.
+     *
+     * <p>
+     * This method may be also invoked during registration of the listener if
+     * there is any pre-existing data in the conceptual data tree for supplied
+     * path. This initial event will contain all pre-existing data as created.
+     *
+     * <p>
+     * A data change event may be triggered spuriously, e.g. such that data before
+     * and after compare as equal. Implementations of this interface are expected
+     * to recover from such events. Event producers are expected to exert reasonable
+     * effort to suppress such events.
+     *
+     * In other words, it is completely acceptable to observe
+     * a {@link org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeCandidateNode},
+     * which reports a {@link org.opendaylight.yangtools.yang.data.api.schema.tree.ModificationType}
+     * other than UNMODIFIED, while the before- and after- data items compare as
+     * equal.
+     *
+     * @param changes Collection of change events, may not be null or empty.
+     */
+    void onDataTreeChanged(@Nonnull Collection<DataTreeCandidate> changes);
+}