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SDK for Microsoft Azure Storage Clients
/**
* Copyright Microsoft Corporation
*
* 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://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 com.microsoft.azure.storage.file;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorCompletionService;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import com.microsoft.azure.storage.AccessCondition;
import com.microsoft.azure.storage.DoesServiceRequest;
import com.microsoft.azure.storage.OperationContext;
import com.microsoft.azure.storage.StorageException;
import com.microsoft.azure.storage.core.Base64;
import com.microsoft.azure.storage.core.SR;
import com.microsoft.azure.storage.core.Utility;
/**
* The class is an append-only stream for writing into storage.
*/
public class FileOutputStream extends OutputStream {
/**
* Holds the reference to the file this stream is associated with.
*/
private final CloudFile parentFileRef;
/**
* A flag to determine if the stream is faulted, if so the lasterror will be thrown on next operation.
*/
volatile boolean streamFaulted;
/**
* Holds the lock for synchronized access to the last error.
*/
Object lastErrorLock = new Object();
/**
* Holds the last exception this stream encountered.
*/
IOException lastError;
/**
* Holds the OperationContext for the current stream.
*/
OperationContext opContext;
/**
* Holds the options for the current stream.
*/
FileRequestOptions options;
/**
* Holds the reference to the MD5 digest for the file.
*/
private MessageDigest md5Digest;
/**
* Holds the currentOffset the stream is writing to.
*/
private long currentOffset;
/**
* A private buffer to store data prior to committing to the cloud.
*/
private ByteArrayOutputStream outBuffer;
/**
* Holds the number of currently buffered bytes.
*/
private int currentBufferedBytes;
/**
* Holds the write threshold of number of bytes to buffer prior to dispatching a write.
*/
private int internalWriteThreshold = -1;
/**
* Holds the number of current outstanding requests.
*/
private volatile int outstandingRequests;
/**
* The ExecutorService used to schedule tasks for this stream.
*/
private final ExecutorService threadExecutor;
/**
* The CompletionService used to await task completion for this stream.
*/
private final ExecutorCompletionService completionService;
/**
* Holds the {@link AccessCondition} object that represents the access conditions for the file.
*/
AccessCondition accessCondition = null;
/**
* Initializes a new instance of the FileOutputStream class.
*
* @param parentFile
* A {@link CloudFile} object which represents the file that this stream is associated with.
* @param length
* A long which represents the length of the file in bytes.
* @param accessCondition
* An {@link AccessCondition} object which represents the access conditions for the file.
* @param options
* A {@link FileRequestOptions} object which specifies any additional options for the request.
* @param opContext
* An {@link OperationContext} object which is used to track the execution of the operation
*
* @throws StorageException
* An exception representing any error which occurred during the operation.
*/
@DoesServiceRequest
protected FileOutputStream(final CloudFile parentFile, final long length, final AccessCondition accessCondition,
final FileRequestOptions options, final OperationContext opContext) throws StorageException {
this.accessCondition = accessCondition;
this.parentFileRef = parentFile;
this.options = new FileRequestOptions(options);
this.outBuffer = new ByteArrayOutputStream();
this.opContext = opContext;
this.streamFaulted = false;
if (this.options.getConcurrentRequestCount() < 1) {
throw new IllegalArgumentException("ConcurrentRequestCount");
}
if (this.options.getStoreFileContentMD5()) {
try {
this.md5Digest = MessageDigest.getInstance("MD5");
}
catch (final NoSuchAlgorithmException e) {
// This wont happen, throw fatal.
throw Utility.generateNewUnexpectedStorageException(e);
}
}
// V2 cachedThreadPool for perf.
this.threadExecutor = Executors.newFixedThreadPool(this.options.getConcurrentRequestCount());
this.completionService = new ExecutorCompletionService(this.threadExecutor);
this.internalWriteThreshold = (int) Math.min(this.parentFileRef.getStreamWriteSizeInBytes(), length);
}
/**
* Helper function to check if the stream is faulted, if it is it surfaces the exception.
*
* @throws IOException
* If an I/O error occurs. In particular, an IOException may be thrown if the output stream has been
* closed.
*/
private void checkStreamState() throws IOException {
synchronized (this.lastErrorLock) {
if (this.streamFaulted) {
throw this.lastError;
}
}
}
/**
* Closes this output stream and releases any system resources associated with this stream. If any data remains in
* the buffer it is committed to the service.
*
* @throws IOException
* If an I/O error occurs.
*/
@Override
@DoesServiceRequest
public void close() throws IOException {
try {
// if the user has already closed the stream, this will throw a STREAM_CLOSED exception
// if an exception was thrown by any thread in the threadExecutor, realize it now
this.checkStreamState();
// flush any remaining data
this.flush();
// shut down the ExecutorService.
this.threadExecutor.shutdown();
// try to commit the file
try {
this.commit();
}
catch (final StorageException e) {
throw Utility.initIOException(e);
}
}
finally {
// if close() is called again, an exception will be thrown
synchronized (this.lastErrorLock) {
this.streamFaulted = true;
this.lastError = new IOException(SR.STREAM_CLOSED);
}
// if an exception was thrown and the executor was not yet closed, call shutDownNow() to cancel all tasks
// and shutdown the ExecutorService
if (!this.threadExecutor.isShutdown()) {
this.threadExecutor.shutdownNow();
}
}
}
/**
* Commits the file.
*
* @throws StorageException
* An exception representing any error which occurred during the operation.
*/
@DoesServiceRequest
private void commit() throws StorageException {
if (this.options.getStoreFileContentMD5()) {
this.parentFileRef.getProperties().setContentMD5(Base64.encode(this.md5Digest.digest()));
}
this.parentFileRef.uploadProperties(this.accessCondition, this.options, this.opContext);
}
/**
* Dispatches a write operation for a given length.
*
* @param writeLength
* An int which represents the length of the data to write, this is the write threshold that
* triggered the write.
*
* @throws IOException
* If an I/O error occurs. In particular, an IOException may be thrown if the output stream has been
* closed.
*/
@DoesServiceRequest
private synchronized void dispatchWrite(final int writeLength) throws IOException {
if (writeLength == 0) {
return;
}
Callable worker = null;
if (this.outstandingRequests > this.options.getConcurrentRequestCount() * 2) {
this.waitForTaskToComplete();
}
final ByteArrayInputStream bufferRef = new ByteArrayInputStream(this.outBuffer.toByteArray());
final CloudFile fileRef = this.parentFileRef;
long tempOffset = this.currentOffset;
long tempLength = writeLength;
final long opWriteLength = tempLength;
final long opOffset = tempOffset;
this.currentOffset += writeLength;
worker = new Callable() {
@Override
public Void call() {
try {
fileRef.uploadRange(bufferRef, opOffset, opWriteLength, FileOutputStream.this.accessCondition,
FileOutputStream.this.options, FileOutputStream.this.opContext);
}
catch (final IOException e) {
synchronized (FileOutputStream.this.lastErrorLock) {
FileOutputStream.this.streamFaulted = true;
FileOutputStream.this.lastError = e;
}
}
catch (final StorageException e) {
synchronized (FileOutputStream.this.lastErrorLock) {
FileOutputStream.this.streamFaulted = true;
FileOutputStream.this.lastError = Utility.initIOException(e);
}
}
return null;
}
};
// Do work and reset buffer.
this.completionService.submit(worker);
this.outstandingRequests++;
this.currentBufferedBytes = 0;
this.outBuffer = new ByteArrayOutputStream();
}
/**
* Flushes this output stream and forces any buffered output bytes to be written out. If any data remains in the
* buffer it is committed to the service.
*
* @throws IOException
* If an I/O error occurs.
*/
@Override
@DoesServiceRequest
public synchronized void flush() throws IOException {
this.checkStreamState();
// Dispatch a write for the current bytes in the buffer
this.dispatchWrite(this.currentBufferedBytes);
// Waits for all submitted tasks to complete
while (this.outstandingRequests > 0) {
// Wait for a task to complete
this.waitForTaskToComplete();
// If that task threw an error, fail fast
this.checkStreamState();
}
}
/**
* Waits for one task to complete
*
* @throws IOException
* If an I/O error occurs. In particular, an IOException may be thrown if the output stream has been
* closed.
*/
private void waitForTaskToComplete() throws IOException {
try {
final Future future = this.completionService.take();
future.get();
}
catch (final InterruptedException e) {
throw Utility.initIOException(e);
}
catch (final ExecutionException e) {
throw Utility.initIOException(e);
}
this.outstandingRequests--;
}
/**
* Writes b.length bytes from the specified byte array to this output stream.
*
* @param data
* A byte array which represents the data to write.
*
* @throws IOException
* If an I/O error occurs. In particular, an IOException may be thrown if the output stream has been
* closed.
*/
@Override
@DoesServiceRequest
public void write(final byte[] data) throws IOException {
this.write(data, 0, data.length);
}
/**
* Writes length bytes from the specified byte array starting at offset to this output stream.
*
* @param data
* A byte array which represents the data to write.
* @param offset
* An int which represents the start offset in the data.
* @param length
* An int which represents the number of bytes to write.
*
* @throws IOException
* If an I/O error occurs. In particular, an IOException may be thrown if the output stream has been
* closed.
*/
@Override
@DoesServiceRequest
public void write(final byte[] data, final int offset, final int length) throws IOException {
if (offset < 0 || length < 0 || length > data.length - offset) {
throw new IndexOutOfBoundsException();
}
this.writeInternal(data, offset, length);
}
/**
* Writes all data from the InputStream to the File.
*
* @param sourceStream
* An {@link InputStream} object which species the data to write to the File.
*
* @throws IOException
* If an I/O error occurs. In particular, an IOException may be thrown if the output stream has been
* closed.
* @throws StorageException
* An exception representing any error which occurred during the operation.
*/
@DoesServiceRequest
public void write(final InputStream sourceStream, final long writeLength) throws IOException, StorageException {
Utility.writeToOutputStream(sourceStream, this, writeLength, false, false, this.opContext, this.options, false);
}
/**
* Writes the specified byte to this output stream. The general contract for write is that one byte is written to
* the output stream. The byte to be written is the eight low-order bits of the argument b. The 24 high-order bits
* of b are ignored.
*
* @param byteVal
* An int which represents the bye value to write.
*
* @throws IOException
* If an I/O error occurs. In particular, an IOException may be thrown if the output stream has been
* closed.
*/
@Override
@DoesServiceRequest
public void write(final int byteVal) throws IOException {
this.write(new byte[] { (byte) (byteVal & 0xFF) });
}
/**
* Writes the data to the buffer and triggers writes to the service as needed.
*
* @param data
* A byte array which represents the data to write.
* @param offset
* An int which represents the start offset in the data.
* @param length
* An int which represents the number of bytes to write.
*
* @throws IOException
* If an I/O error occurs. In particular, an IOException may be thrown if the output stream has been
* closed.
*/
@DoesServiceRequest
private synchronized void writeInternal(final byte[] data, int offset, int length) throws IOException {
while (length > 0) {
this.checkStreamState();
final int availableBufferBytes = this.internalWriteThreshold - this.currentBufferedBytes;
final int nextWrite = Math.min(availableBufferBytes, length);
// If we need to set MD5 then update the digest accordingly
if (this.options.getStoreFileContentMD5()) {
this.md5Digest.update(data, offset, nextWrite);
}
this.outBuffer.write(data, offset, nextWrite);
this.currentBufferedBytes += nextWrite;
offset += nextWrite;
length -= nextWrite;
if (this.currentBufferedBytes == this.internalWriteThreshold) {
this.dispatchWrite(this.internalWriteThreshold);
}
}
}
}