Simplify DataSource to be a function that provides Stream of values

This patch also removes the old automatic update logic.

Change-Id: Idb50137eee2592c1acd14ff67f577ad5edbbd2ff

8 files changed, 92 insertions, 388 deletions

diff --git a/server/src/main/java/com/vaadin/tokka/server/communication/data/AbstractDataSource.java b/server/src/main/java/com/vaadin/tokka/server/communication/data/AbstractDataSource.java
deleted file mode 100644
index 4e2bfbf6bf..0000000000
--- a/server/src/main/java/com/vaadin/tokka/server/communication/data/AbstractDataSource.java
+++ /dev/null
@@ -1,97 +0,0 @@
-/*
- * Copyright 2000-2014 Vaadin Ltd.
- * 
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not
- * use this file except in compliance with the License. You may obtain a copy of
- * the License at
- * 
- * http://www.apache.org/licenses/LICENSE-2.0
- * 
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
- * License for the specific language governing permissions and limitations under
- * the License.
- */
-package com.vaadin.tokka.server.communication.data;
-
-import java.util.LinkedHashSet;
-import java.util.Set;
-
-import com.vaadin.tokka.event.Registration;
-
-/**
- * Base class for AbstractDataSource. Provides tracking for
- * {@link DataChangeHandler}s and helper methods to call them.
- * 
- * @since
- */
-public abstract class AbstractDataSource<T> implements DataSource<T> {
-
-    protected final Set<DataChangeHandler<T>> handlers = new LinkedHashSet<DataChangeHandler<T>>();
-
-    @Override
-    public Registration addDataChangeHandler(DataChangeHandler<T> handler) {
-        if (handler != null) {
-            handlers.add(handler);
-            return () -> handlers.remove(handler);
-        }
-        return () -> { /* NO-OP */ };
-    }
-
-    /**
-     * Informs all handlers of a generic change in the data. This usually
-     * triggers a full cache invalidation and refresh of all data, which is
-     * usually an expensive operation. Should be called when none of the other
-     * methods help.
-     * 
-     * @see #fireDataAppend(Object)
-     * @see #fireDataRemove(Object)
-     * @see #fireDataUpdate(Object)
-     */
-    protected void fireDataChange() {
-        for (DataChangeHandler<T> handler : handlers) {
-            handler.onDataChange();
-        }
-    }
-
-    /**
-     * Informs all handlers of an added data object in the back end. This method
-     * should only be called when the newly added data object is the last object
-     * in the back end. Other additions can be handled with
-     * {@link #fireDataChange()}.
-     * 
-     * @param data
-     *            added data object
-     */
-    protected void fireDataAppend(T data) {
-        for (DataChangeHandler<T> handler : handlers) {
-            handler.onDataAppend(data);
-        }
-    }
-
-    /**
-     * Informs all handlers of a data object that was removed from the back end.
-     * 
-     * @param data
-     *            removed data object
-     */
-    protected void fireDataRemove(T data) {
-        for (DataChangeHandler<T> handler : handlers) {
-            handler.onDataRemove(data);
-        }
-    }
-
-    /**
-     * Informs all handlers of an existing data object that was updated in the
-     * back end.
-     * 
-     * @param data
-     *            updated data object
-     */
-    protected void fireDataUpdate(T data) {
-        for (DataChangeHandler<T> handler : handlers) {
-            handler.onDataUpdate(data);
-        }
-    }
-}
diff --git a/server/src/main/java/com/vaadin/tokka/server/communication/data/DataCommunicator.java b/server/src/main/java/com/vaadin/tokka/server/communication/data/DataCommunicator.java
index 19b4ed8965..0a9e3f34c7 100644
--- a/server/src/main/java/com/vaadin/tokka/server/communication/data/DataCommunicator.java
+++ b/server/src/main/java/com/vaadin/tokka/server/communication/data/DataCommunicator.java
@@ -25,7 +25,6 @@ import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
 import com.vaadin.server.AbstractExtension;
-import com.vaadin.server.ClientConnector;
 import com.vaadin.shared.data.DataRequestRpc;
 import com.vaadin.shared.data.typed.DataCommunicatorClientRpc;
 import com.vaadin.shared.data.typed.DataProviderConstants;
@@ -72,8 +71,8 @@ public class DataCommunicator<T> extends AbstractExtension {
      * longer needed. Data tracking is based on key string provided by
      * {@link DataKeyMapper}.
      * <p>
-     * When the {@link DataCommunicator} is pushing new data to the client-side via
-     * {@link DataCommunicator#pushData(long, Collection)},
+     * When the {@link DataCommunicator} is pushing new data to the client-side
+     * via {@link DataCommunicator#pushData(long, Collection)},
      * {@link #addActiveData(Collection)} and {@link #cleanUp(Collection)} are
      * called with the same parameter. In the clean up method any dropped data
      * objects that are not in the given collection will be cleaned up and
@@ -173,8 +172,6 @@ public class DataCommunicator<T> extends AbstractExtension {
     protected DataCommunicatorClientRpc rpc;
 
     protected DataSource<T> dataSource;
-    private Registration dataChangeHandler;
-    private DetachListener detachListener;
     private DataKeyMapper<T> keyMapper;
 
     private boolean reset = false;
@@ -186,8 +183,6 @@ public class DataCommunicator<T> extends AbstractExtension {
         this.dataSource = dataSource;
         rpc = getRpcProxy(DataCommunicatorClientRpc.class);
         registerRpc(createRpc());
-        dataChangeHandler = this.dataSource
-                .addDataChangeHandler(createDataChangeHandler());
         keyMapper = createKeyMapper();
     }
 
@@ -200,11 +195,13 @@ public class DataCommunicator<T> extends AbstractExtension {
         super.beforeClientResponse(initial);
 
         if (initial || reset) {
-            rpc.reset(dataSource.size());
+            // FIXME: Rethink the size question.
+            rpc.reset((int) dataSource.apply(null).count());
         }
 
         if (!pushRows.isEmpty()) {
-            Stream<T> rowsToPush = dataSource.request()
+            // FIXME: Query object
+            Stream<T> rowsToPush = dataSource.apply(null)
                     .skip(pushRows.getStart()).limit(pushRows.length());
             pushData(pushRows.getStart(), rowsToPush);
         }
@@ -223,32 +220,6 @@ public class DataCommunicator<T> extends AbstractExtension {
         updatedData.clear();
     }
 
-    @Override
-    public void attach() {
-        super.attach();
-
-        if (detachListener == null) {
-            detachListener = new DetachListener() {
-
-                @Override
-                public void detach(DetachEvent event) {
-                    cleanUp();
-                }
-            };
-            getUI().addDetachListener(detachListener);
-        }
-    }
-
-    @Override
-    public void setParent(ClientConnector parent) {
-        if (getParent() != null && parent == null) {
-            // Removing from parent, clean up.
-            cleanUp();
-        }
-
-        super.setParent(parent);
-    }
-
     /**
      * Adds a {@link TypedDataGenerator} to this {@link DataCommunicator}.
      * 
@@ -341,22 +312,6 @@ public class DataCommunicator<T> extends AbstractExtension {
     }
 
     /**
-     * Clean up method for removing all listeners attached by the
-     * {@link DataCommunicator}. This method is called from {@link #remove()} or
-     * when the UI gets detached.
-     */
-    protected void cleanUp() {
-        if (dataSource != null) {
-            dataChangeHandler.removeHandler();
-            dataChangeHandler = null;
-        }
-        if (detachListener != null) {
-            getUI().removeDetachListener(detachListener);
-            detachListener = null;
-        }
-    }
-
-    /**
      * Informs the DataProvider that a data object has been added. It is assumed
      * to be the last object in the collection.
      * 
@@ -406,7 +361,7 @@ public class DataCommunicator<T> extends AbstractExtension {
     }
 
     /**
-     * Creates a {@link DataKeyMapper} to use with this {@link DataCommunicator}.
+     * Creates a {@link DataKeyMapper} to use with this DataCommunicator.
      * <p>
      * This method is called from the constructor.
      * 
@@ -426,36 +381,4 @@ public class DataCommunicator<T> extends AbstractExtension {
     protected DataRequestRpc createRpc() {
         return new SimpleDataRequestRpc();
     }
-
-    /**
-     * Creates a {@link DataChangeHandler} to use with the {@link DataSource}.
-     * <p>
-     * This method is called from the constructor.
-     * 
-     * @return data change handler
-     */
-    protected DataChangeHandler<T> createDataChangeHandler() {
-        return new DataChangeHandler<T>() {
-
-            @Override
-            public void onDataChange() {
-                reset();
-            }
-
-            @Override
-            public void onDataAppend(T data) {
-                add(data);
-            }
-
-            @Override
-            public void onDataRemove(T data) {
-                remove(data);
-            }
-
-            @Override
-            public void onDataUpdate(T data) {
-                refresh(data);
-            }
-        };
-    }
 }
\ No newline at end of file
diff --git a/server/src/main/java/com/vaadin/tokka/server/communication/data/DataSource.java b/server/src/main/java/com/vaadin/tokka/server/communication/data/DataSource.java
index ea851a04f7..01257bf755 100644
--- a/server/src/main/java/com/vaadin/tokka/server/communication/data/DataSource.java
+++ b/server/src/main/java/com/vaadin/tokka/server/communication/data/DataSource.java
@@ -18,6 +18,7 @@ package com.vaadin.tokka.server.communication.data;
 import java.io.Serializable;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.function.Function;
 import java.util.stream.Stream;
 
 import com.vaadin.tokka.event.Registration;
@@ -25,74 +26,40 @@ import com.vaadin.tokka.event.Registration;
 /**
  * Minimal DataSource API for communication between the DataProvider and a back
  * end service.
+ * <p>
+ * FIXME: Missing Query class
  * 
  * @since
  * @param <T>
  *            data type
  */
-public interface DataSource<T> extends Serializable {
+public interface DataSource<T> extends Function<Object, Stream<T>>,
+        Serializable {
 
     /**
-     * Requests data from the back end.
-     * 
-     * @return stream of results
-     */
-    Stream<T> request(/* Query query */);
-
-    /**
-     * Saves a data object to the back end. If it's a new object, it should be
-     * created in the back end. Existing objects with changes should be stored.
-     * 
-     * @param data
-     *            data object to save
-     */
-    void save(T data);
-
-    /**
-     * Removes the given data object from the back end.
-     * 
-     * @param data
-     *            data object to remove
-     */
-    void remove(T data);
-
-    /**
-     * TODO: Decide the fate of the size method.
-     * 
-     * @return size of the data source
-     */
-    int size();
-
-    /**
-     * Adds a new DataChangeHandler to this DataSource. DataChangeHandler is
-     * called when changes occur in DataSource.
-     * 
-     * @param handler
-     *            data change handler
-     */
-    Registration addDataChangeHandler(DataChangeHandler<T> handler);
-
-    /**
-     * This method creates a new {@link ListDataSource} from a given Collection.
-     * The ListDataSource creates a protective List copy of all the contents in
-     * the Collection.
+     * This method creates a new {@link InMemoryDataSource} from a given
+     * Collection. The InMemoryDataSource creates a protective List copy of all
+     * the contents in the Collection.
      * 
      * @param data
      *            collection of data
-     * @return list data source
+     * @return in-memory data source
      */
-    public static <T> ListDataSource<T> create(Collection<T> data) {
-        return new ListDataSource<>(data);
+    public static <T> InMemoryDataSource<T> create(Collection<T> data) {
+        return new InMemoryDataSource<>(data);
     }
 
     /**
-     * This method creates a new {@link ListDataSource} from given objects.
+     * This method creates a new {@link InMemoryDataSource} from given
+     * objects.The InMemoryDataSource creates a protective List copy of all the
+     * contents in the array.
      * 
      * @param data
      *            data objects
-     * @return list data source
+     * @return in-memory data source
      */
-    public static <T> ListDataSource<T> create(T... data) {
-        return new ListDataSource<>(Arrays.asList(data));
+    @SafeVarargs
+    public static <T> InMemoryDataSource<T> create(T... data) {
+        return new InMemoryDataSource<>(Arrays.asList(data));
     }
 }
\ No newline at end of file
diff --git a/server/src/main/java/com/vaadin/tokka/server/communication/data/ListDataSource.java b/server/src/main/java/com/vaadin/tokka/server/communication/data/InMemoryDataSource.java
index ab9f84940b..5f743e2ca1 100644
--- a/server/src/main/java/com/vaadin/tokka/server/communication/data/ListDataSource.java
+++ b/server/src/main/java/com/vaadin/tokka/server/communication/data/InMemoryDataSource.java
@@ -18,6 +18,7 @@ package com.vaadin.tokka.server.communication.data;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.function.Function;
 import java.util.stream.Stream;
 
 /**
@@ -26,9 +27,10 @@ import java.util.stream.Stream;
  * @param <T>
  *            data type
  */
-public class ListDataSource<T> extends AbstractDataSource<T> {
+public class InMemoryDataSource<T> implements DataSource<T> {
 
-    private List<T> backend;
+    // FIXME: Missing Query object
+    private Function<Object, Stream<T>> request;
 
     /**
      * Constructs a new ListDataSource. This method makes a protective copy of
@@ -37,35 +39,13 @@ public class ListDataSource<T> extends AbstractDataSource<T> {
      * @param collection
      *            initial data
      */
-    public ListDataSource(Collection<T> collection) {
-        backend = new ArrayList<T>(collection);
+    public InMemoryDataSource(Collection<T> collection) {
+        final List<T> backend = new ArrayList<T>(collection);
+        request = query -> backend.stream();
     }
 
     @Override
-    public void save(T data) {
-        if (!backend.contains(data)) {
-            backend.add(data);
-            fireDataAppend(data);
-        } else {
-            fireDataUpdate(data);
-        }
-    }
-
-    @Override
-    public void remove(T data) {
-        if (backend.contains(data)) {
-            backend.remove(data);
-            fireDataRemove(data);
-        }
-    }
-
-    @Override
-    public Stream<T> request() {
-        return backend.stream();
-    }
-
-    @Override
-    public int size() {
-        return backend.size();
+    public Stream<T> apply(Object query) {
+        return request.apply(query);
     }
 }
diff --git a/server/src/test/java/com/vaadin/tokka/data/datasource/InMemoryDataSourceTest.java b/server/src/test/java/com/vaadin/tokka/data/datasource/InMemoryDataSourceTest.java
new file mode 100644
index 0000000000..092f70b395
--- /dev/null
+++ b/server/src/test/java/com/vaadin/tokka/data/datasource/InMemoryDataSourceTest.java
@@ -0,0 +1,55 @@
+package com.vaadin.tokka.data.datasource;
+
+import static org.junit.Assert.assertTrue;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import com.vaadin.tokka.server.communication.data.DataSource;
+import com.vaadin.tokka.server.communication.data.InMemoryDataSource;
+
+public class InMemoryDataSourceTest {
+
+    private static class StrBean {
+
+        private String value;
+
+        public StrBean(String value) {
+            this.value = value;
+        }
+
+        public String getValue() {
+            return value;
+        }
+
+        public void setValue(String value) {
+            this.value = value;
+        }
+
+    }
+
+    private InMemoryDataSource<StrBean> dataSource;
+    private List<StrBean> data;
+
+    @Before
+    public void setUp() {
+        data = createData();
+        dataSource = DataSource.create(data);
+    }
+
+    @Test
+    public void testListContainsAllData() {
+        dataSource.apply(null).forEach(str -> assertTrue(data.contains(str)));
+    }
+
+    private List<StrBean> createData() {
+        List<StrBean> list = new ArrayList<>();
+        Stream.of("Foo", "Bar", "Baz").map(StrBean::new).forEach(list::add);
+        return list;
+    }
+
+}
diff --git a/server/src/test/java/com/vaadin/tokka/data/datasource/ListDataSourceTest.java b/server/src/test/java/com/vaadin/tokka/data/datasource/ListDataSourceTest.java
deleted file mode 100644
index 58a3fa8b48..0000000000
--- a/server/src/test/java/com/vaadin/tokka/data/datasource/ListDataSourceTest.java
+++ /dev/null
@@ -1,100 +0,0 @@
-package com.vaadin.tokka.data.datasource;
-
-import static org.junit.Assert.assertTrue;
-
-import java.util.ArrayList;
-import java.util.List;
-import java.util.stream.Stream;
-
-import org.easymock.EasyMock;
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
-
-import com.vaadin.tokka.server.communication.data.DataChangeHandler;
-import com.vaadin.tokka.server.communication.data.DataSource;
-import com.vaadin.tokka.server.communication.data.ListDataSource;
-
-public class ListDataSourceTest {
-
-    private static class StrBean {
-
-        private String value;
-
-        public StrBean(String value) {
-            this.value = value;
-        }
-
-        public String getValue() {
-            return value;
-        }
-
-        public void setValue(String value) {
-            this.value = value;
-        }
-
-    }
-
-    private ListDataSource<StrBean> dataSource;
-    private List<StrBean> data;
-    private DataChangeHandler<StrBean> handler;
-
-    @Before
-    public void setUp() {
-        data = createData();
-        dataSource = DataSource.create(data);
-        handler = EasyMock.mock(DataChangeHandler.class);
-    }
-
-    @Test
-    public void testListContainsAllData() {
-        EasyMock.replay(handler);
-        dataSource.request().forEach(str -> assertTrue(data.contains(str)));
-    }
-
-    @Test
-    public void testListFiresDataAddEvent() {
-        StrBean strBean = new StrBean("Spam");
-        handler.onDataAppend(strBean);
-        EasyMock.expectLastCall().times(1);
-        EasyMock.replay(handler);
-
-        dataSource.addDataChangeHandler(handler);
-        dataSource.save(strBean);
-    }
-
-    @Test
-    public void testListFiresDataRemoveEvent() {
-        StrBean strBean = data.get(0);
-        handler.onDataRemove(strBean);
-        EasyMock.expectLastCall().times(1);
-        EasyMock.replay(handler);
-
-        dataSource.addDataChangeHandler(handler);
-        dataSource.remove(strBean);
-    }
-
-    @Test
-    public void testListFiresDataUpdateEvent() {
-        StrBean strBean = data.get(0);
-        handler.onDataUpdate(strBean);
-        EasyMock.expectLastCall().times(1);
-        EasyMock.replay(handler);
-
-        dataSource.addDataChangeHandler(handler);
-        strBean.setValue("Fuu");
-        dataSource.save(strBean);
-    }
-
-    @After
-    public void tearDown() {
-        EasyMock.verify(handler);
-    }
-
-    private List<StrBean> createData() {
-        List<StrBean> list = new ArrayList<>();
-        Stream.of("Foo", "Bar", "Baz").map(StrBean::new).forEach(list::add);
-        return list;
-    }
-
-}
diff --git a/server/src/test/java/com/vaadin/tokka/ui/components/AbstractListingTest.java b/server/src/test/java/com/vaadin/tokka/ui/components/AbstractListingTest.java
index 614e1aba72..242b5519df 100644
--- a/server/src/test/java/com/vaadin/tokka/ui/components/AbstractListingTest.java
+++ b/server/src/test/java/com/vaadin/tokka/ui/components/AbstractListingTest.java
@@ -2,15 +2,11 @@ package com.vaadin.tokka.ui.components;
 
 import static org.junit.Assert.assertEquals;
 
-import java.util.stream.Stream;
-
 import org.junit.Before;
 import org.junit.Test;
 
-import com.vaadin.tokka.server.communication.data.AbstractDataSource;
 import com.vaadin.tokka.server.communication.data.DataCommunicator;
 import com.vaadin.tokka.server.communication.data.DataSource;
-import com.vaadin.tokka.ui.components.AbstractListing;
 import com.vaadin.tokka.ui.components.AbstractListing.AbstractListingExtension;
 
 import elemental.json.JsonObject;
@@ -49,26 +45,7 @@ public class AbstractListingTest {
 
     @Before
     public void setUp() {
-        testComponent.setDataSource(new AbstractDataSource<String>() {
-
-            @Override
-            public void save(String data) {
-            }
-
-            @Override
-            public void remove(String data) {
-            }
-
-            @Override
-            public Stream<String> request() {
-                return Stream.of("Foo");
-            }
-
-            @Override
-            public int size() {
-                return 1;
-            }
-        });
+        testComponent.setDataSource(DataSource.create("Foo"));
     }
 
     @Test
diff --git a/uitest/src/main/java/com/vaadin/tokka/tests/components/ListingTestUI.java b/uitest/src/main/java/com/vaadin/tokka/tests/components/ListingTestUI.java
index 683be11e47..a66ab31fda 100644
--- a/uitest/src/main/java/com/vaadin/tokka/tests/components/ListingTestUI.java
+++ b/uitest/src/main/java/com/vaadin/tokka/tests/components/ListingTestUI.java
@@ -62,7 +62,6 @@ public class ListingTestUI extends AbstractTestUI {
                         .nextInt(100)));
             }
             return beans;
-
         }
     }
 
@@ -82,8 +81,8 @@ public class ListingTestUI extends AbstractTestUI {
                 .forEach(s -> Notification.show(s))));
         hLayout.addComponent(new Button("Random select", e -> {
             DataSource<String> ds = select.getDataSource();
-            int skip = r.nextInt(ds.size());
-            ds.request().skip(skip).findFirst()
+            int skip = r.nextInt((int) ds.apply(null).count());
+            ds.apply(null).skip(skip).findFirst()
                     .ifPresent(select.getSelectionModel()::select);
         }));