/*
* Copyright 2002-2016 the original author or authors.
*
* 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 org.springframework.core.io.buffer.support;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import java.nio.channels.Channels;
import java.nio.channels.ReadableByteChannel;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import org.reactivestreams.Publisher;
import reactor.core.publisher.Flux;
import reactor.core.subscriber.SignalEmitter;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.core.io.buffer.PooledDataBuffer;
import org.springframework.util.Assert;
/**i
* Utility class for working with {@link DataBuffer}s.
*
* @author Arjen Poutsma
*/
public abstract class DataBufferUtils {
private static final Consumer<ReadableByteChannel> CLOSE_CONSUMER = channel -> {
try {
if (channel != null) {
channel.close();
}
}
catch (IOException ignored) {
}
};
/**
* Reads the given {@code InputStream} into a {@code Flux} of
* {@code DataBuffer}s. Closes the input stream when the flux is terminated.
* @param inputStream the input stream to read from
* @param dataBufferFactory the factory to create data buffers with
* @param bufferSize the maximum size of the data buffers
* @return a flux of data buffers read from the given channel
*/
public static Flux<DataBuffer> read(InputStream inputStream,
DataBufferFactory dataBufferFactory, int bufferSize) {
Assert.notNull(inputStream, "'inputStream' must not be null");
Assert.notNull(dataBufferFactory, "'dataBufferFactory' must not be null");
ReadableByteChannel channel = Channels.newChannel(inputStream);
return read(channel, dataBufferFactory, bufferSize);
}
/**
* Reads the given {@code ReadableByteChannel} into a {@code Flux} of
* {@code DataBuffer}s. Closes the channel when the flux is terminated.
* @param channel the channel to read from
* @param dataBufferFactory the factory to create data buffers with
* @param bufferSize the maximum size of the data buffers
* @return a flux of data buffers read from the given channel
*/
public static Flux<DataBuffer> read(ReadableByteChannel channel,
DataBufferFactory dataBufferFactory, int bufferSize) {
Assert.notNull(channel, "'channel' must not be null");
Assert.notNull(dataBufferFactory, "'dataBufferFactory' must not be null");
return Flux.generate(() -> channel,
new ReadableByteChannelGenerator(dataBufferFactory, bufferSize),
CLOSE_CONSUMER);
}
/**
* Relays buffers from the given {@link Publisher} until the total
* {@linkplain DataBuffer#readableByteCount() byte count} reaches the given maximum
* byte count, or until the publisher is complete.
* @param publisher the publisher to filter
* @param maxByteCount the maximum byte count
* @return a flux whose maximum byte count is {@code maxByteCount}
*/
public static Flux<DataBuffer> takeUntilByteCount(Publisher<DataBuffer> publisher,
long maxByteCount) {
Assert.notNull(publisher, "'publisher' must not be null");
Assert.isTrue(maxByteCount >= 0, "'maxByteCount' must be a positive number");
AtomicLong byteCountDown = new AtomicLong(maxByteCount);
return Flux.from(publisher).
takeWhile(dataBuffer -> {
int delta = -dataBuffer.readableByteCount();
long currentCount = byteCountDown.getAndAdd(delta);
return currentCount >= 0;
}).
map(dataBuffer -> {
long currentCount = byteCountDown.get();
if (currentCount >= 0) {
return dataBuffer;
}
else {
// last buffer
int size = (int) (currentCount + dataBuffer.readableByteCount());
return dataBuffer.slice(0, size);
}
});
}
/**
* Retains the given data buffer, it it is a {@link PooledDataBuffer}.
* @param dataBuffer the data buffer to retain
* @return the retained buffer
*/
@SuppressWarnings("unchecked")
public static <T extends DataBuffer> T retain(T dataBuffer) {
if (dataBuffer instanceof PooledDataBuffer) {
return (T) ((PooledDataBuffer) dataBuffer).retain();
}
else {
return dataBuffer;
}
}
/**
* Releases the given data buffer, if it is a {@link PooledDataBuffer}.
* @param dataBuffer the data buffer to release
* @return {@code true} if the buffer was released; {@code false} otherwise.
*/
public static boolean release(DataBuffer dataBuffer) {
if (dataBuffer instanceof PooledDataBuffer) {
return ((PooledDataBuffer) dataBuffer).release();
}
return false;
}
private static class ReadableByteChannelGenerator
implements BiFunction<ReadableByteChannel, SignalEmitter<DataBuffer>,
ReadableByteChannel> {
private final DataBufferFactory dataBufferFactory;
private final int chunkSize;
public ReadableByteChannelGenerator(DataBufferFactory dataBufferFactory,
int chunkSize) {
this.dataBufferFactory = dataBufferFactory;
this.chunkSize = chunkSize;
}
@Override
public ReadableByteChannel apply(ReadableByteChannel
channel, SignalEmitter<DataBuffer> sub) {
try {
ByteBuffer byteBuffer = ByteBuffer.allocate(chunkSize);
int read;
if ((read = channel.read(byteBuffer)) > 0) {
byteBuffer.flip();
boolean release = true;
DataBuffer dataBuffer = this.dataBufferFactory.allocateBuffer(read);
try {
dataBuffer.write(byteBuffer);
release = false;
sub.next(dataBuffer);
}
finally {
if (release) {
release(dataBuffer);
}
}
}
else {
sub.complete();
}
}
catch (IOException ex) {
sub.fail(ex);
}
return channel;
}
}
}