flink-runtime/src/main/java/org/apache/flink/runtime/blob/TransientBlobService.java

/*
 * 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 java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;

/**
 * A service to retrieve transient binary large objects (BLOBs) which are deleted on the {@link
 * BlobServer} when they are retrieved.
 *
 * <p>These may include per-job BLOBs like files in the {@link
 * org.apache.flink.api.common.cache.DistributedCache}, for example.
 *
 * <p>Note: None of these BLOBs is highly available (HA). This case is covered by BLOBs in the
 * {@link PermanentBlobService}.
 *
 * <p>TODO: change API to not rely on local files but return {@link InputStream} objects
 */
public interface TransientBlobService extends Closeable {

    // --------------------------------------------------------------------------------------------
    //  GET
    // --------------------------------------------------------------------------------------------

    /**
     * Returns the path to a local copy of the (job-unrelated) file associated with the provided
     * blob key.
     *
     * @param key blob key associated with the requested file
     * @return The path to the file.
     * @throws java.io.FileNotFoundException when the path does not exist;
     * @throws IOException if any other error occurs when retrieving the file
     */
    File getFile(TransientBlobKey key) throws IOException;

    /**
     * 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 when the path does not exist;
     * @throws IOException if any other error occurs when retrieving the file
     */
    File getFile(JobID jobId, TransientBlobKey key) throws IOException;

    // --------------------------------------------------------------------------------------------
    //  PUT
    // --------------------------------------------------------------------------------------------

    /**
     * Uploads the (job-unrelated) data of the given byte array to the BLOB server.
     *
     * @param value the buffer to upload
     * @return the computed BLOB key identifying the BLOB on the server
     * @throws IOException thrown if an I/O error occurs while uploading the data to the BLOB server
     */
    TransientBlobKey putTransient(byte[] value) throws IOException;

    /**
     * Uploads the data of the given byte array for the given job to the BLOB server.
     *
     * @param jobId the ID of the job the BLOB belongs to
     * @param value the buffer to upload
     * @return the computed BLOB key identifying the BLOB on the server
     * @throws IOException thrown if an I/O error occurs while uploading the data to the BLOB server
     */
    TransientBlobKey putTransient(JobID jobId, byte[] value) throws IOException;

    /**
     * Uploads the (job-unrelated) data from the given input stream to the BLOB server.
     *
     * @param inputStream the input stream to read the data from
     * @return the computed BLOB key identifying the BLOB on the server
     * @throws IOException thrown if an I/O error occurs while reading the data from the input
     *     stream or uploading the data to the BLOB server
     */
    TransientBlobKey putTransient(InputStream inputStream) throws IOException;

    /**
     * Uploads the data from the given input stream for the given job to the BLOB server.
     *
     * @param jobId ID of the job this blob belongs to
     * @param inputStream the input stream to read the data from
     * @return the computed BLOB key identifying the BLOB on the server
     * @throws IOException thrown if an I/O error occurs while reading the data from the input
     *     stream or uploading the data to the BLOB server
     */
    TransientBlobKey putTransient(JobID jobId, InputStream inputStream) throws IOException;

    // --------------------------------------------------------------------------------------------
    //  DELETE
    // --------------------------------------------------------------------------------------------

    /**
     * Deletes the (job-unrelated) file associated with the provided blob key from the local cache.
     *
     * @param key associated with the file to be deleted
     * @return <tt>true</tt> if the given blob is successfully deleted or non-existing;
     *     <tt>false</tt> otherwise
     */
    boolean deleteFromCache(TransientBlobKey key);

    /**
     * Deletes the file associated with the provided job ID and blob key from the local cache.
     *
     * @param jobId ID of the job this blob belongs to
     * @param key associated with the file to be deleted
     * @return <tt>true</tt> if the given blob is successfully deleted or non-existing;
     *     <tt>false</tt> otherwise
     */
    boolean deleteFromCache(JobID jobId, TransientBlobKey key);
}