com.qcloud.cos.transfer.DownloadCallable Maven / Gradle / Ivy
/*
* Copyright 2010-2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License").
* You may not use this file except in compliance with the License.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. 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.
* According to cos feature, we modify some class，comment, field name, etc.
*/
package com.qcloud.cos.transfer;
import java.io.File;
import java.net.SocketException;
import java.util.Arrays;
import java.util.concurrent.Callable;
import java.util.concurrent.CountDownLatch;
import javax.net.ssl.SSLProtocolException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.qcloud.cos.COS;
import com.qcloud.cos.exception.CosClientException;
import com.qcloud.cos.exception.FileLockException;
import com.qcloud.cos.internal.FileLocks;
import com.qcloud.cos.model.COSObject;
import com.qcloud.cos.model.GetObjectRequest;
import com.qcloud.cos.transfer.Transfer.TransferState;
import com.qcloud.cos.utils.ServiceUtils;
import com.qcloud.cos.utils.ServiceUtils.RetryableCOSDownloadTask;
final class DownloadCallable implements Callable {
private static final Logger log = LoggerFactory.getLogger(DownloadCallable.class);
private final COS cos;
private final CountDownLatch latch;
private final GetObjectRequest req;
private final boolean resumeExistingDownload;
private final DownloadImpl download;
private final File dstfile;
private final long origStartingByte;
private long expectedFileLength;
DownloadCallable(COS cos, CountDownLatch latch, GetObjectRequest req,
boolean resumeExistingDownload, DownloadImpl download, File dstfile,
long origStartingByte, long expectedFileLength) {
if (cos == null || latch == null || req == null || dstfile == null || download == null)
throw new IllegalArgumentException();
this.cos = cos;
this.latch = latch;
this.req = req;
this.resumeExistingDownload = resumeExistingDownload;
this.download = download;
this.dstfile = dstfile;
this.origStartingByte = origStartingByte;
this.expectedFileLength = expectedFileLength;
}
/**
* This method must return a non-null object, or else the existing implementation in
* {@link AbstractTransfer#waitForCompletion()} would block forever.
*
* @return the downloaded file
*/
@Override
public File call() throws Exception {
try {
latch.await();
download.setState(TransferState.InProgress);
COSObject cosObject = retryableDownloadCOSObjectToFile(dstfile,
new DownloadTaskImpl(cos, download, req), resumeExistingDownload);
if (cosObject == null) {
download.setState(TransferState.Canceled);
download.setMonitor(new DownloadMonitor(download, null));
} else {
download.setState(TransferState.Completed);
}
return dstfile;
} catch (Throwable t) {
// Downloads aren't allowed to move from canceled to failed
if (download.getState() != TransferState.Canceled) {
download.setState(TransferState.Failed);
}
if (t instanceof Exception)
throw (Exception) t;
else
throw (Error) t;
}
}
/**
* This method is called only if it is a resumed download.
*
* Adjust the range of the get request, and the expected (ie current) file length of the
* destination file to append to.
*/
private void adjustRequest(GetObjectRequest req) {
long[] range = req.getRange();
long lastByte = range[1];
long totalBytesToDownload = lastByte - this.origStartingByte + 1;
if (dstfile.exists()) {
if (!FileLocks.lock(dstfile)) {
throw new FileLockException("Fail to lock " + dstfile + " for range adjustment");
}
try {
expectedFileLength = dstfile.length();
long startingByte = this.origStartingByte + expectedFileLength;
log.info("Adjusting request range from " + Arrays.toString(range) + " to "
+ Arrays.toString(new long[] {startingByte, lastByte}) + " for file "
+ dstfile);
req.setRange(startingByte, lastByte);
totalBytesToDownload = lastByte - startingByte + 1;
} finally {
FileLocks.unlock(dstfile);
}
}
if (totalBytesToDownload < 0) {
throw new IllegalArgumentException(
"Unable to determine the range for download operation. lastByte=" + lastByte
+ ", origStartingByte=" + origStartingByte + ", expectedFileLength="
+ expectedFileLength + ", totalBytesToDownload="
+ totalBytesToDownload);
}
}
private COSObject retryableDownloadCOSObjectToFile(File file,
RetryableCOSDownloadTask retryableCOSDownloadTask, boolean appendData) {
boolean hasRetried = false;
COSObject cosObject;
for (;;) {
if (resumeExistingDownload && hasRetried) {
// Need to adjust the get range or else we risk corrupting the downloaded file
adjustRequest(req);
}
cosObject = retryableCOSDownloadTask.getCOSObjectStream();
if (cosObject == null)
return null;
try {
if (testing && resumeExistingDownload && !hasRetried) {
throw new CosClientException("testing");
}
ServiceUtils.downloadToFile(cosObject, file,
retryableCOSDownloadTask.needIntegrityCheck(), appendData,
expectedFileLength);
return cosObject;
} catch (CosClientException ace) {
if (!ace.isRetryable())
throw ace;
// Determine whether an immediate retry is needed according to the captured
// CosClientException.
// (There are three cases when downloadObjectToFile() throws CosClientException:
// 1) SocketException or SSLProtocolException when writing to disk (e.g. when user
// aborts the download)
// 2) Other IOException when writing to disk
// 3) MD5 hashes don't match
// The current code will retry the download only when case 2) or 3) happens.
if (ace.getCause() instanceof SocketException
|| ace.getCause() instanceof SSLProtocolException) {
throw ace;
} else {
if (hasRetried)
throw ace;
else {
log.info("Retry the download of object " + cosObject.getKey() + " (bucket "
+ cosObject.getBucketName() + ")", ace);
hasRetried = true;
}
}
} finally {
cosObject.getObjectContent().abort();
}
}
}
private static boolean testing;
/**
* Used for testing purpose only.
*/
static void setTesting(boolean b) {
testing = b;
}
}
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