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https://issues.apache.org/jira/browse/FLINK-5823?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16320776#comment-16320776
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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_r160759604
--- Diff:
flink-runtime/src/main/java/org/apache/flink/runtime/state/StateBackendLoader.java
---
@@ -0,0 +1,265 @@
+/*
+ * 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.configuration.CheckpointingOptions;
+import org.apache.flink.configuration.Configuration;
+import org.apache.flink.configuration.HighAvailabilityOptions;
+import org.apache.flink.configuration.IllegalConfigurationException;
+import org.apache.flink.core.fs.Path;
+import org.apache.flink.runtime.jobmanager.HighAvailabilityMode;
+import org.apache.flink.runtime.state.filesystem.FsStateBackend;
+import org.apache.flink.runtime.state.filesystem.FsStateBackendFactory;
+import org.apache.flink.runtime.state.memory.MemoryStateBackend;
+import org.apache.flink.runtime.state.memory.MemoryStateBackendFactory;
+import org.apache.flink.util.DynamicCodeLoadingException;
+
+import org.slf4j.Logger;
+
+import javax.annotation.Nullable;
+
+import java.io.IOException;
+import java.util.UUID;
+
+import static org.apache.flink.util.Preconditions.checkNotNull;
+
+/**
+ * This class contains utility methods to load state backends from
configurations.
+ */
+public class StateBackendLoader {
+
+ //
------------------------------------------------------------------------
+ // Configuration shortcut names
+ //
------------------------------------------------------------------------
+
+ /** The shortcut configuration name for the MemoryState backend that
checkpoints to the JobManager */
+ public static final String MEMORY_STATE_BACKEND_NAME = "jobmanager";
+
+ /** The shortcut configuration name for the FileSystem State backend */
+ public static final String FS_STATE_BACKEND_NAME = "filesystem";
+
+ /** The shortcut configuration name for the RocksDB State Backend */
+ public static final String ROCKSDB_STATE_BACKEND_NAME = "rocksdb";
+
+ //
------------------------------------------------------------------------
+ // Loading the state backend from a configuration
+ //
------------------------------------------------------------------------
+
+ /**
+ * Loads the state backend from the configuration, from the parameter
'state.backend', as defined
+ * in {@link CheckpointingOptions#STATE_BACKEND}.
+ *
+ * <p>The state backends can be specified either via their shortcut
name, or via the class name
+ * of a {@link StateBackendFactory}. If a StateBackendFactory class
name is specified, the factory
+ * is instantiated (via its zero-argument constructor) and its
+ * {@link StateBackendFactory#createFromConfig(Configuration)} method
is called.
+ *
+ * <p>Recognized shortcut names are '{@value
StateBackendLoader#MEMORY_STATE_BACKEND_NAME}',
+ * '{@value StateBackendLoader#FS_STATE_BACKEND_NAME}', and
+ * '{@value StateBackendLoader#ROCKSDB_STATE_BACKEND_NAME}'.
+ *
+ * @param config The configuration to load the state backend from
+ * @param classLoader The class loader that should be used to load the
state backend
+ * @param logger Optionally, a logger to log actions to (may be null)
+ *
+ * @return The instantiated state backend.
+ *
+ * @throws DynamicCodeLoadingException
+ * Thrown if a state backend factory is configured and the
factory class was not
+ * found or the factory could not be instantiated
+ * @throws IllegalConfigurationException
+ * May be thrown by the StateBackendFactory when creating /
configuring the state
+ * backend in the factory
+ * @throws IOException
+ * May be thrown by the StateBackendFactory when
instantiating the state backend
+ */
+ public static StateBackend loadStateBackendFromConfig(
+ Configuration config,
+ ClassLoader classLoader,
+ @Nullable Logger logger) throws
IllegalConfigurationException, DynamicCodeLoadingException, IOException {
+
+ checkNotNull(config, "config");
+ checkNotNull(classLoader, "classLoader");
+
+ final String backendName =
config.getString(CheckpointingOptions.STATE_BACKEND);
+ if (backendName == null) {
+ return null;
+ }
+
+ // by default the factory class is the backend name
+ String factoryClassName = backendName;
+
+ switch (backendName.toLowerCase()) {
--- End diff --
I don't understand this comment. Users can still implement their own
backends and put the classname in the config. This method only adds some simply
some redefined short names for common backends (the same that were there
before).
> 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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