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https://issues.apache.org/jira/browse/FLINK-5823?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16320757#comment-16320757
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ASF GitHub Bot commented on FLINK-5823:
---------------------------------------
Github user StephanEwen commented on a diff in the pull request:
https://github.com/apache/flink/pull/5248#discussion_r160756970
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/state/CheckpointStorage.java
---
@@ -0,0 +1,93 @@
+/*
+ * 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 javax.annotation.Nullable;
+
+import java.io.IOException;
+
+/**
+ * CheckpointStorage implements the durable storage of checkpoint data and
metadata streams.
+ * An individual checkpoint or savepoint is stored to a {@link
CheckpointStorageLocation},
+ * created by this class.
+ */
+public interface CheckpointStorage {
+
+ /**
+ * Checks whether this backend supports highly available storage of
data.
+ *
+ * <p>Some state backends may offer support for that with default
settings, which makes them
+ * suitable for zero-config prototyping, but not for actual production
setups.
+ */
+ boolean supportsHighlyAvailableStorage();
+
+ /**
+ * Checks whether the storage has a default savepoint location
configured.
+ */
+ boolean hasDefaultSavepointLocation();
+
+ /**
+ * Resolves the given pointer to a checkpoint/savepoint into a state
handle from which the
+ * checkpoint metadata can be read. If the state backend cannot
understand the format of
+ * the pointer (for example because it was created by a different state
backend) this method
+ * should throw an {@code IOException}.
+ *
+ * @param pointer The pointer to resolve.
+ * @return The state handler from which one can read the checkpoint
metadata.
+ *
+ * @throws IOException Thrown, if the state backend does not understand
the pointer, or if
+ * the pointer could not be resolved due to an I/O
error.
+ */
+ StreamStateHandle resolveCheckpoint(String pointer) throws IOException;
+
+ /**
+ * Initializes a storage location for new checkpoint with the given ID.
+ *
+ * <p>The returned storage location can be used to write the checkpoint
data and metadata
+ * to and to obtain the pointers for the location(s) where the actual
checkpoint data should be
+ * stored.
+ *
+ * @param checkpointId The ID (logical timestamp) of the checkpoint
that should be persisted.
+ * @return A storage location for the data and metadata of the given
checkpoint.
+ *
+ * @throws IOException Thrown if the storage location cannot be
initialized due to an I/O exception.
+ */
+ CheckpointStorageLocation initializeCheckpoint(long checkpointId)
throws IOException;
--- End diff --
How about `initializeLocationForCheckpoint`?
> Store Checkpoint Root Metadata in StateBackend (not in HA custom store)
> -----------------------------------------------------------------------
>
> Key: FLINK-5823
> URL: https://issues.apache.org/jira/browse/FLINK-5823
> Project: Flink
> Issue Type: Sub-task
> Components: State Backends, Checkpointing
> Reporter: Stephan Ewen
> Assignee: Stephan Ewen
> Priority: Blocker
> Fix For: 1.5.0
>
>
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