org.xnio.channels.BlockingReadableByteChannel Maven / Gradle / Ivy
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*
* Copyright 2009 Red Hat, Inc. and/or its affiliates.
*
* 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.xnio.channels;
import static org.xnio._private.Messages.msg;
import java.nio.channels.ScatteringByteChannel;
import java.nio.ByteBuffer;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
import org.xnio.Buffers;
/**
* A blocking wrapper for a {@code StreamSourceChannel}. Read operations will block until some data may be transferred.
* Once any amount of data is read, the operation will return. If a read timeout is specified, then the read methods
* will throw a {@link ReadTimeoutException} if the timeout expires without reading any data.
*/
public class BlockingReadableByteChannel implements ScatteringByteChannel {
private final StreamSourceChannel delegate;
private volatile long readTimeout;
/**
* Construct a new instance.
*
* @param delegate the channel to forward I/O operations to
*/
public BlockingReadableByteChannel(final StreamSourceChannel delegate) {
this.delegate = delegate;
}
/**
* Construct a new instance.
*
* @param delegate the channel to forward I/O operations to
* @param readTimeout the read timeout
* @param readTimeoutUnit the read timeout unit
*/
public BlockingReadableByteChannel(final StreamSourceChannel delegate, final long readTimeout, final TimeUnit readTimeoutUnit) {
if (readTimeout < 0L) {
throw msg.parameterOutOfRange("readTimeout");
}
this.delegate = delegate;
final long calcTimeout = readTimeoutUnit.toNanos(readTimeout);
this.readTimeout = readTimeout == 0L ? 0L : calcTimeout < 1L ? 1L : calcTimeout;
}
/**
* Set the read timeout.
*
* @param readTimeout the read timeout
* @param readTimeoutUnit the read timeout unit
*/
public void setReadTimeout(long readTimeout, TimeUnit readTimeoutUnit) {
if (readTimeout < 0L) {
throw msg.parameterOutOfRange("readTimeout");
}
final long calcTimeout = readTimeoutUnit.toNanos(readTimeout);
this.readTimeout = readTimeout == 0L ? 0L : calcTimeout < 1L ? 1L : calcTimeout;
}
/**
* Perform a blocking, scattering read operation.
*
* @param dsts the destination buffers
* @param offset the offset into the destination buffer array
* @param length the number of buffers to read into
* @return the number of bytes actually read (will be greater than zero)
* @throws IOException if an I/O error occurs
*/
public long read(final ByteBuffer[] dsts, final int offset, final int length) throws IOException {
if (!Buffers.hasRemaining(dsts, offset, length)) {
return 0L;
}
final StreamSourceChannel delegate = this.delegate;
long res;
if ((res = delegate.read(dsts, offset, length)) == 0L) {
long start = System.nanoTime();
long elapsed = 0L, readTimeout;
do {
readTimeout = this.readTimeout;
if (readTimeout == 0L || readTimeout == Long.MAX_VALUE) {
delegate.awaitReadable();
} else if (readTimeout <= elapsed) {
throw msg.readTimeout();
} else {
delegate.awaitReadable(readTimeout - elapsed, TimeUnit.NANOSECONDS);
}
elapsed = System.nanoTime() - start;
} while ((res = delegate.read(dsts, offset, length)) == 0L);
}
return res;
}
/**
* Perform a blocking, scattering read operation.
*
* @param dsts the destination buffers
* @return the number of bytes actually read (will be greater than zero)
* @throws IOException if an I/O error occurs
*/
public long read(final ByteBuffer[] dsts) throws IOException {
return read(dsts, 0, dsts.length);
}
/**
* Perform a blocking read operation.
*
* @param dst the destination buffer
* @return the number of bytes actually read (will be greater than zero)
* @throws IOException if an I/O error occurs
*/
public int read(final ByteBuffer dst) throws IOException {
if (! dst.hasRemaining()) {
return 0;
}
final StreamSourceChannel delegate = this.delegate;
int res;
if ((res = delegate.read(dst)) == 0) {
long start = System.nanoTime();
long elapsed = 0L, readTimeout;
do {
readTimeout = this.readTimeout;
if (readTimeout == 0L || readTimeout == Long.MAX_VALUE) {
delegate.awaitReadable();
} else if (readTimeout <= elapsed) {
throw msg.readTimeout();
} else {
delegate.awaitReadable(readTimeout - elapsed, TimeUnit.NANOSECONDS);
}
elapsed = System.nanoTime() - start;
} while ((res = delegate.read(dst)) == 0);
}
return res;
}
/** {@inheritDoc} */
public boolean isOpen() {
return delegate.isOpen();
}
/** {@inheritDoc} */
public void close() throws IOException {
delegate.close();
}
}