/*
* Copyright (C) 2015 SoftIndex LLC.
*
* 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 io.datakernel.stream.file;
import io.datakernel.async.CompletionCallback;
import io.datakernel.async.IgnoreCompletionCallback;
import io.datakernel.async.ResultCallback;
import io.datakernel.bytebuf.ByteBuf;
import io.datakernel.bytebuf.ByteBufPool;
import io.datakernel.eventloop.Eventloop;
import io.datakernel.file.AsyncFile;
import io.datakernel.stream.AbstractStreamProducer;
import io.datakernel.stream.StreamStatus;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.nio.file.OpenOption;
import java.nio.file.Path;
import java.nio.file.StandardOpenOption;
import java.util.concurrent.ExecutorService;
import static java.lang.Math.min;
/**
* This class allows you to read data from file non-blocking. It represents a {@link AbstractStreamProducer}
* which streams data from file.
*/
public final class StreamFileReader extends AbstractStreamProducer<ByteBuf> {
private final Logger logger = LoggerFactory.getLogger(this.getClass());
private final AsyncFile asyncFile;
private final int bufferSize;
private long position;
private long length;
private boolean pendingAsyncOperation;
private ResultCallback<Long> positionCallback;
// region creators
private StreamFileReader(Eventloop eventloop, AsyncFile asyncFile,
int bufferSize, long position, long length) {
super(eventloop);
this.asyncFile = asyncFile;
this.bufferSize = bufferSize;
this.position = position;
this.length = length;
}
public static StreamFileReader readFileSegment(Eventloop eventloop, AsyncFile asyncFile,
int bufferSize, long position, long length) {
return new StreamFileReader(eventloop, asyncFile, bufferSize, position, length);
}
public static StreamFileReader readFileFrom(final Eventloop eventloop, ExecutorService executor,
final int bufferSize, Path path,
final long startPosition) throws IOException {
AsyncFile asyncFile = getAsyncFile(eventloop, executor, path);
return readFileFrom(eventloop, asyncFile, bufferSize, startPosition);
}
public static StreamFileReader readFileFrom(Eventloop eventloop, AsyncFile asyncFile,
int bufferSize, long position) {
return new StreamFileReader(eventloop, asyncFile, bufferSize, position, Long.MAX_VALUE);
}
public static StreamFileReader readFileFully(final Eventloop eventloop, ExecutorService executor,
final int bufferSize, Path path) throws IOException {
AsyncFile asyncFile = getAsyncFile(eventloop, executor, path);
return readFileFully(eventloop, asyncFile, bufferSize);
}
public static StreamFileReader readFileFully(Eventloop eventloop, AsyncFile asyncFile, int bufferSize) {
return new StreamFileReader(eventloop, asyncFile, bufferSize, 0, Long.MAX_VALUE);
}
// endregion
// region api
public void setPositionCallback(ResultCallback<Long> positionCallback) {
if (getProducerStatus().isOpen()) {
this.positionCallback = positionCallback;
} else {
if (getProducerStatus() == StreamStatus.END_OF_STREAM) {
positionCallback.setResult(position);
} else {
positionCallback.setException(getProducerException());
}
}
}
public long getPosition() {
return position;
}
// endregion
// region functional
protected void doFlush() {
if (getProducerStatus().isClosed()) {
return;
}
if (length == 0L) {
doCleanup(IgnoreCompletionCallback.create());
sendEndOfStream();
return;
}
final ByteBuf buf = ByteBufPool.allocate((int) min(bufferSize, length));
asyncFile.read(buf, position, new ResultCallback<Integer>() {
@Override
protected void onResult(Integer result) {
if (getProducerStatus().isClosed()) {
buf.recycle();
doCleanup(IgnoreCompletionCallback.create());
return;
}
pendingAsyncOperation = false;
if (result == -1) {
buf.recycle();
doCleanup(IgnoreCompletionCallback.create());
sendEndOfStream();
if (positionCallback != null) {
positionCallback.setResult(position);
}
return;
} else {
position += result;
send(buf);
if (length != Long.MAX_VALUE) {
length -= result;
}
}
if (isStatusReady()) {
postFlush();
}
}
@Override
protected void onException(Exception e) {
buf.recycle();
doCleanup(IgnoreCompletionCallback.create());
closeWithError(e);
if (positionCallback != null) {
positionCallback.setException(e);
}
}
});
}
protected void postFlush() {
if (!pendingAsyncOperation) {
pendingAsyncOperation = true;
eventloop.post(new Runnable() {
@Override
public void run() {
doFlush();
}
});
logger.trace("{}: posted flush", this);
}
}
@Override
public void onSuspended() {
logger.trace("{}: downstream consumer {} suspended.", this, downstreamConsumer);
}
@Override
public void onResumed() {
logger.trace("{}: downstream consumer {} resumed.", this, downstreamConsumer);
postFlush();
}
@Override
protected void onStarted() {
logger.info("{}: started reading", this);
postFlush();
}
@Override
protected void onError(Exception e) {
logger.error("{}: onError", this, e);
doCleanup(IgnoreCompletionCallback.create());
}
protected void doCleanup(final CompletionCallback callback) {
logger.info("{}: finished reading", this);
asyncFile.close(new CompletionCallback() {
@Override
protected void onComplete() {
logger.trace("{}: closed file", this);
callback.setComplete();
}
@Override
protected void onException(Exception exception) {
logger.error("{}: failed to close file", this, exception);
callback.setException(exception);
}
});
}
private static AsyncFile getAsyncFile(Eventloop eventloop, ExecutorService executor, Path path) throws IOException {
return AsyncFile.open(eventloop, executor, path, new OpenOption[]{StandardOpenOption.READ});
}
@Override
public String toString() {
return "StreamFileReader{" + asyncFile +
", pos=" + position +
(length == Long.MAX_VALUE ? "" : ", len=" + length) +
(pendingAsyncOperation ? ", pendingAsyncOperation" : "") +
'}';
}
// endregion
}