[GitHub] [flink] sjwiesman commented on a change in pull request #8615: [FLINK-12729][state-processor-api] Add state reader for consuming non-partitioned operator state

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sjwiesman commented on a change in pull request #8615:  [FLINK-12729][state-processor-api] Add state reader for consuming non-partitioned operator state
URL: https://github.com/apache/flink/pull/8615#discussion_r296688271
 
 

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 File path: flink-libraries/flink-state-processing-api/src/main/java/org/apache/flink/state/api/runtime/SavepointLoader.java
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 @@ -0,0 +1,54 @@
+/*
+ * 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.state.api.runtime;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.runtime.checkpoint.Checkpoints;
+import org.apache.flink.runtime.checkpoint.savepoint.Savepoint;
+import org.apache.flink.runtime.state.CompletedCheckpointStorageLocation;
+import org.apache.flink.runtime.state.filesystem.AbstractFsCheckpointStorage;
+
+import java.io.DataInputStream;
+import java.io.IOException;
+
+/**
+ * Utility class for loading {@link Savepoint} metadata.
+ */
+@Internal
+public final class SavepointLoader {
+	private SavepointLoader() {}
+
+	/**
+	 * Takes the given string (representing a pointer to a checkpoint) and resolves it to a file
+	 * status for the checkpoint's metadata file.
+	 *
+	 * @param savepointPath The path to an external savepoint.
+	 * @return A state handle to savepoint's metadata.
+	 * @throws IOException Thrown, if the path cannot be resolved, the file system not accessed, or
+	 *     the path points to a location that does not seem to be a savepoint.
+	 */
+	public static Savepoint loadSavepoint(String savepointPath) throws IOException {
+		CompletedCheckpointStorageLocation location = AbstractFsCheckpointStorage
+			.resolveCheckpointPointer(savepointPath);
+
+		try (DataInputStream stream = new DataInputStream(location.getMetadataHandle().openInputStream())) {
+			return Checkpoints.loadCheckpointMetadata(stream, NullClassLoader.INSTANCE);
 
 Review comment:
   There was one place where I couldn't get access to the user classloader but it wasn't being used so I decided to go this route. However, if we do the reading on the client the current thread class loader should be the user class loader so that makes it easier. 

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