Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/flink/pull/2781#discussion_r91076224
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/state/MultiStreamStateHandle.java
---
@@ -0,0 +1,96 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you 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 org.apache.flink.runtime.state;
+
+import org.apache.flink.core.fs.AbstractMultiFSDataInputStream;
+import org.apache.flink.core.fs.FSDataInputStream;
+import org.apache.flink.util.Preconditions;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Map;
+import java.util.TreeMap;
+
+/**
+ * Wrapper class that takes multiple {@link StreamStateHandle} and makes
them look like a single one. This is done by
+ * providing a contiguous view on all the streams of the inner handles
through a wrapper stream and by summing up all
+ * all the meta data.
+ */
+public class MultiStreamStateHandle implements StreamStateHandle {
+
+ private static final long serialVersionUID = -4588701089489569707L;
+ private final List<StreamStateHandle> stateHandles;
+ private final long stateSize;
+
+ public MultiStreamStateHandle(List<StreamStateHandle> stateHandles)
throws IOException {
--- End diff --
Would be good to either reject empty lists, or add a test that validates
that this works with empty lists of streams.
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