org.apache.flink.runtime.blob.PermanentBlobService Maven / Gradle / Ivy
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* 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.blob;
import org.apache.flink.api.common.JobID;
import org.apache.flink.util.FileUtils;
import java.io.Closeable;
import java.io.File;
import java.io.IOException;
/**
* A service to retrieve permanent binary large objects (BLOBs).
*
* These may include per-job BLOBs that are covered by high-availability (HA) mode, e.g. a job's
* JAR files or (parts of) an off-loaded {@link
* org.apache.flink.runtime.deployment.TaskDeploymentDescriptor} or files in the {@link
* org.apache.flink.api.common.cache.DistributedCache}.
*/
public interface PermanentBlobService extends Closeable {
/**
* Returns the path to a local copy of the file associated with the provided job ID and blob
* key.
*
* @param jobId ID of the job this blob belongs to
* @param key BLOB key associated with the requested file
* @return The path to the file.
* @throws java.io.FileNotFoundException if the BLOB does not exist;
* @throws IOException if any other error occurs when retrieving the file
*/
File getFile(JobID jobId, PermanentBlobKey key) throws IOException;
/**
* Returns the content of the file for the BLOB with the provided job ID the blob key.
*
*
Compared to {@code getFile}, {@code readFile} will attempt to read the entire file after
* retrieving it. If file reading and file retrieving is done in the same WRITE lock, it can
* avoid the scenario that the path to the file is deleted concurrently by other threads when
* the file is retrieved but not read yet.
*
* @param jobId ID of the job this blob belongs to
* @param key BLOB key associated with the requested file
* @return The content of the BLOB.
* @throws java.io.FileNotFoundException if the BLOB does not exist;
* @throws IOException if any other error occurs when retrieving the file.
*/
default byte[] readFile(JobID jobId, PermanentBlobKey key) throws IOException {
// The default implementation doesn't guarantee that the file won't be deleted concurrently
// by other threads while reading the contents.
return FileUtils.readAllBytes(getFile(jobId, key).toPath());
}
}