com.amazonaws.services.s3.transfer.internal.MultipleFileDownloadImpl Maven / Gradle / Ivy

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The Amazon Web Services SDK for Java provides Java APIs for building software on AWS' cost-effective, scalable, and reliable infrastructure products. The AWS Java SDK allows developers to code against APIs for all of Amazon's infrastructure web services (Amazon S3, Amazon EC2, Amazon SQS, Amazon Relational Database Service, Amazon AutoScaling, etc).

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/*
 * Copyright 2012-2014 Amazon Technologies, Inc.
 *
 * Licensed 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://aws.amazon.com/apache2.0
 *
 * This file 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 com.amazonaws.services.s3.transfer.internal;

import java.io.IOException;
import java.util.Collection;

import com.amazonaws.AmazonClientException;
import com.amazonaws.AmazonServiceException;
import com.amazonaws.event.ProgressListenerChain;
import com.amazonaws.services.s3.transfer.Download;
import com.amazonaws.services.s3.transfer.MultipleFileDownload;
import com.amazonaws.services.s3.transfer.Transfer;
import com.amazonaws.services.s3.transfer.TransferProgress;

/**
 * Multiple file download when downloading an entire virtual directory.
 */
public class MultipleFileDownloadImpl extends MultipleFileTransfer implements MultipleFileDownload {

    private final String keyPrefix;
    private final String bucketName;
    
    public MultipleFileDownloadImpl(String description, TransferProgress transferProgress,
            ProgressListenerChain progressListenerChain, String keyPrefix, String bucketName, Collection downloads) {
        super(description, transferProgress, progressListenerChain, downloads);
        this.keyPrefix = keyPrefix;
        this.bucketName = bucketName;
    }
    
    /**
     * @deprecated Replaced by {@link #MultipleFileDownloadImpl(String, TransferProgress, ProgressListenerChain, String, String, Collection)}
     */
    @Deprecated
    public MultipleFileDownloadImpl(String description, TransferProgress transferProgress,
            com.amazonaws.services.s3.transfer.internal.ProgressListenerChain progressListenerChain, String keyPrefix, String bucketName, Collection downloads) {
        this(description, transferProgress, progressListenerChain.transformToGeneralProgressListenerChain(), 
                keyPrefix, bucketName, downloads);
    }

    /**
     * Returns the key prefix of the virtual directory being downloaded.
     */
    public String getKeyPrefix() {
        return keyPrefix;
    }
    
    /**
     * Returns the name of the bucket from which files are downloaded.
     */
    public String getBucketName() {
        return bucketName;
    }
   
    /**
     * Waits for this transfer to complete. This is a blocking call; the current
     * thread is suspended until this transfer completes.
     *
     * @throws AmazonClientException
     *             If any errors were encountered in the client while making the
     *             request or handling the response.
     * @throws AmazonServiceException
     *             If any errors occurred in Amazon S3 while processing the
     *             request.
     * @throws InterruptedException
     *             If this thread is interrupted while waiting for the transfer
     *             to complete.
     */
    @Override
    public void waitForCompletion()
            throws AmazonClientException, AmazonServiceException, InterruptedException {
        if (subTransfers.isEmpty())
            return;
        super.waitForCompletion();
    }
    
    /**
     * Aborts all outstanding downloads.
     */
    public void abort() throws IOException {
        /*
         * The abort() method of DownloadImpl would attempt to notify its
         * TransferStateChangeListener BEFORE it releases its intrinsic lock.
         * And according to the implementation of
         * MultipleFileTransferStateChangeListener which is actually shared by
         * all sub-transfers, it will call the synchronized method isDone() on
         * ALL sub-transfer objects. This would result in serious
         * contention with the worker threads who try to acquire the same set of
         * locks to call setState().
         * In order to prevent this. we should first cancel all download jobs and
         * then notify the listener.
         */
        
        /* First abort all the download jobs without notifying the state change listener.*/
        for (Transfer fileDownload : subTransfers) {
            ((DownloadImpl)fileDownload).abortWithoutNotifyingStateChangeListener();
        }
        
        /*
         * All sub-transfers are already in CANCELED state. Now the main thread
         * is able to check isDone() on each sub-transfer object without
         * contention with worker threads.
         */
        for (Transfer fileDownload : subTransfers) {
            ((DownloadImpl)fileDownload).notifyStateChangeListeners(TransferState.Canceled);
        }
    }
}