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https://issues.apache.org/jira/browse/FLINK-4067?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15361349#comment-15361349
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ASF GitHub Bot commented on FLINK-4067:
---------------------------------------
Github user tillrohrmann commented on a diff in the pull request:
https://github.com/apache/flink/pull/2194#discussion_r69461170
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/checkpoint/savepoint/SavepointStore.java
---
@@ -0,0 +1,71 @@
+/*
+ * 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.checkpoint.savepoint;
+
+/**
+ * Savepoint store used to persist {@link Savepoint} instances.
+ *
+ * <p>The main implementation is the {@link FsSavepointStore}. We also
have the
+ * {@link HeapSavepointStore} for historical reasons (introduced in Flink
1.0).
+ */
+public interface SavepointStore {
+
+ /**
+ * Stores the savepoint.
+ *
+ * @param savepoint Savepoint to be stored
+ * @param <T> Savepoint type
+ * @return Path of stored savepoint
+ * @throws Exception Failures during store are forwarded
+ */
+ <T extends Savepoint> String storeSavepoint(T savepoint) throws
Exception;
+
+ /**
+ * Loads the savepoint at the specified path.
+ *
+ * @param path Path of savepoint to load
+ * @return The loaded savepoint
+ * @throws Exception Failures during load are forwared
+ */
+ Savepoint loadSavepoint(String path) throws Exception;
+
+ /**
+ * Disposes the savepoint at the specified path.
+ *
+ * <p>The class loader is needed, because savepoints can currently
point to
+ * arbitrary snapshot {@link org.apache.flink.runtime.state.StateHandle}
+ * instances, which need the user code class loader for deserialization.
+ *
+ * @param path Path of savepoint to dispose
+ * @param classLoader Class loader for disposal
+ * @throws Exception Failures during diposal are forwarded
+ */
+ void disposeSavepoint(String path, ClassLoader classLoader) throws
Exception;
+
+ /**
+ * Shut downs the savepoint store.
+ *
+ * <p>Only necessary for implementations where the savepoint life-cycle
is
+ * bound to the cluster life-cycle.
+ *
+ * @throws Exception Failures during shut down are forwarded
+ */
+ void shutDown() throws Exception;
--- End diff --
I think so far we've usually written shutdown without a capital letter.
> Add version header to savepoints
> --------------------------------
>
> Key: FLINK-4067
> URL: https://issues.apache.org/jira/browse/FLINK-4067
> Project: Flink
> Issue Type: Improvement
> Affects Versions: 1.0.3
> Reporter: Ufuk Celebi
> Assignee: Ufuk Celebi
> Fix For: 1.1.0
>
>
> Adding a header with version information to savepoints ensures that we can
> migrate savepoints between Flink versions in the future (for example when
> changing internal serialization formats between versions).
> After talking with Till, we propose to add the following meta data:
> - Magic number (int): identify data as savepoint
> - Version (int): savepoint version (independent of Flink version)
> - Data Offset (int): specifies at which point the actual savepoint data
> starts. With this, we can allow future Flink versions to add fields to the
> header without breaking stuff, e.g. Flink 1.1 could read savepoints of Flink
> 2.0.
> For Flink 1.0 savepoint support, we have to try reading the savepoints
> without a header before failing if we don't find the magic number.
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