Change DataSource addDataChangeHandler() return type to Registration

Remove DataSource removeDataChangeHandler()

Change-Id: I07a92ad6e7d2c75ca8f53a3376d0b8157559cb70

server/src/main/java/com/vaadin/server/communication/data/typed/AbstractDataSource.java

@@ -18,6 +18,8 @@ package com.vaadin.server.communication.data.typed;
 import java.util.LinkedHashSet;
 import java.util.Set;
 
+import com.vaadin.event.handler.Registration;
+
 /**
  * Base class for AbstractDataSource. Provides tracking for
  * {@link DataChangeHandler}s and helper methods to call them.
@@ -26,18 +28,15 @@ import java.util.Set;
  */
 public abstract class AbstractDataSource<T> implements DataSource<T> {
 
-    protected Set<DataChangeHandler<T>> handlers = new LinkedHashSet<DataChangeHandler<T>>();
+    protected final Set<DataChangeHandler<T>> handlers = new LinkedHashSet<DataChangeHandler<T>>();
 
     @Override
-    public void addDataChangeHandler(DataChangeHandler<T> handler) {
+    public Registration addDataChangeHandler(DataChangeHandler<T> handler) {
         if (handler != null) {
             handlers.add(handler);
+            return () -> handlers.remove(handler);
         }
-    }
-
-    @Override
-    public void removeDataChangeHandler(DataChangeHandler<T> handler) {
-        handlers.remove(handler);
+        return () -> { /* NO-OP */ };
     }
 
     /**

server/src/main/java/com/vaadin/server/communication/data/typed/DataProvider.java

@@ -21,6 +21,7 @@ import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.Set;
 
+import com.vaadin.event.handler.Registration;
 import com.vaadin.server.AbstractExtension;
 import com.vaadin.server.ClientConnector;
 import com.vaadin.shared.data.DataRequestRpc;
@@ -172,7 +173,7 @@ public abstract class DataProvider<T> extends AbstractExtension {
     protected DataProviderClientRpc rpc;
 
     protected DataSource<T> dataSource;
-    private DataChangeHandler<T> dataChangeHandler;
+    private Registration dataChangeHandler;
     private DetachListener detachListener;
     private DataKeyMapper<T> keyMapper;
 
@@ -181,8 +182,8 @@ public abstract class DataProvider<T> extends AbstractExtension {
         this.dataSource = dataSource;
         rpc = getRpcProxy(DataProviderClientRpc.class);
         registerRpc(createRpc());
-        dataChangeHandler = createDataChangeHandler();
-        this.dataSource.addDataChangeHandler(dataChangeHandler);
+        dataChangeHandler = this.dataSource
+                .addDataChangeHandler(createDataChangeHandler());
         keyMapper = createKeyMapper();
     }
 
@@ -242,7 +243,7 @@ public abstract class DataProvider<T> extends AbstractExtension {
     public DataKeyMapper<T> getKeyMapper() {
         return keyMapper;
     }
-    
+
     public abstract void refresh(T data);
 
     /**
@@ -311,7 +312,7 @@ public abstract class DataProvider<T> extends AbstractExtension {
      */
     protected void cleanUp() {
         if (dataSource != null) {
-            dataSource.removeDataChangeHandler(dataChangeHandler);
+            dataChangeHandler.removeHandler();
             dataChangeHandler = null;
         }
         if (detachListener != null) {

server/src/main/java/com/vaadin/server/communication/data/typed/DataSource.java

@@ -19,6 +19,8 @@ import java.io.Serializable;
 import java.util.Arrays;
 import java.util.Collection;
 
+import com.vaadin.event.handler.Registration;
+
 /**
  * Minimal DataSource API for communication between the DataProvider and a back
  * end service.
@@ -53,15 +55,7 @@ public interface DataSource<T> extends Iterable<T>, Serializable {
      * @param handler
      *            data change handler
      */
-    void addDataChangeHandler(DataChangeHandler<T> handler);
-
-    /**
-     * Removed a DataChangeHandler from this DataSource.
-     * 
-     * @param handler
-     *            data change handler
-     */
-    void removeDataChangeHandler(DataChangeHandler<T> handler);
+    Registration addDataChangeHandler(DataChangeHandler<T> handler);
 
     /**
      * This method creates a new {@link ListDataSource} from a given Collection.