From ce88f6fd1b0ac1dd12337762c59c1cda450e6b11 Mon Sep 17 00:00:00 2001
From: Teemu Suo-Anttila <teemusa@vaadin.com>
Date: Tue, 12 Jul 2016 19:02:29 +0300
Subject: [PATCH] Add method to DataSource for checking if data is in memory

Change-Id: I7b14870a3eddb477e629f61691e060ea42325aea
---
 .../server/communication/data/DataCommunicator.java    |  2 +-
 .../tokka/server/communication/data/DataSource.java    | 10 ++++++++--
 .../server/communication/data/InMemoryDataSource.java  |  5 +++++
 3 files changed, 14 insertions(+), 3 deletions(-)

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 dc957f6abd..e5d3269641 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
@@ -215,7 +215,7 @@ public class DataCommunicator<T> extends AbstractExtension {
 
             Stream<T> rowsToPush;
 
-            if (getDataSource() instanceof InMemoryDataSource) {
+            if (getDataSource().isInMemory()) {
                 // We can safely request all the data when in memory
                 // FIXME: sorted and filter.
                 rowsToPush = getDataSource().apply(new Query()).skip(offset)
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 38a195e953..17f0355bd2 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
@@ -21,8 +21,6 @@ import java.util.Collection;
 import java.util.function.Function;
 import java.util.stream.Stream;
 
-import com.vaadin.tokka.event.Registration;
-
 /**
  * Minimal DataSource API for communication between the DataProvider and a back
  * end service.
@@ -45,6 +43,14 @@ public interface DataSource<T, SORT> extends Function<Query, Stream<T>>,
      */
     DataSource<T, SORT> sortingBy(SORT sortOrder);
 
+    /**
+     * Gets whether the DataSource content all available in memory or does it
+     * use some external backend.
+     * 
+     * @return {@code true} if all data is in memory; {@code false} if not
+     */
+    boolean isInMemory();
+
     /**
      * This method creates a new {@link InMemoryDataSource} from a given
      * Collection. The InMemoryDataSource creates a protective List copy of all
diff --git a/server/src/main/java/com/vaadin/tokka/server/communication/data/InMemoryDataSource.java b/server/src/main/java/com/vaadin/tokka/server/communication/data/InMemoryDataSource.java
index 49ca85d403..b5dc0734c2 100644
--- a/server/src/main/java/com/vaadin/tokka/server/communication/data/InMemoryDataSource.java
+++ b/server/src/main/java/com/vaadin/tokka/server/communication/data/InMemoryDataSource.java
@@ -72,4 +72,9 @@ public class InMemoryDataSource<T> implements DataSource<T, Comparator<T>> {
             Function<T, U> sortOrder) {
         return sortingBy(Comparator.comparing(sortOrder));
     }
+
+    @Override
+    public boolean isInMemory() {
+        return true;
+    }
 }
-- 
2.39.5