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/*
* JBoss, Home of Professional Open Source
*
* Copyright 2010 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.streams;
import java.io.InputStream;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.nio.ByteBuffer;
import static java.lang.Math.min;
import static org.xnio._private.Messages.msg;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
import org.xnio.Bits;
import org.xnio.Buffers;
import org.xnio.channels.Channels;
import org.xnio.channels.StreamSourceChannel;
/**
* An input stream which reads from a stream source channel with a buffer. In addition, the
* {@link #available()} method can be used to determine whether the next read will or will not block.
*
* @apiviz.exclude
*
* @since 2.1
*/
public class BufferedChannelInputStream extends InputStream {
private final StreamSourceChannel channel;
private final ByteBuffer buffer;
@SuppressWarnings("unused")
private volatile int flags;
private volatile long timeout;
private static final AtomicIntegerFieldUpdater flagsUpdater = AtomicIntegerFieldUpdater.newUpdater(BufferedChannelInputStream.class, "flags");
private static final int FLAG_EOF = 2;
private static final int FLAG_ENTERED = 1;
/**
* Construct a new instance.
*
* @param channel the channel to wrap
* @param bufferSize the size of the internal buffer
*/
public BufferedChannelInputStream(final StreamSourceChannel channel, final int bufferSize) {
if (channel == null) {
throw msg.nullParameter("channel");
}
if (bufferSize < 1) {
throw msg.parameterOutOfRange("bufferSize");
}
this.channel = channel;
buffer = ByteBuffer.allocate(bufferSize);
buffer.limit(0);
}
/**
* Construct a new instance.
*
* @param channel the channel to wrap
* @param bufferSize the size of the internal buffer
* @param timeout the initial read timeout, or O for none
* @param unit the time unit for the read timeout
*/
public BufferedChannelInputStream(final StreamSourceChannel channel, final int bufferSize, final long timeout, final TimeUnit unit) {
if (channel == null) {
throw msg.nullParameter("channel");
}
if (unit == null) {
throw msg.nullParameter("unit");
}
if (bufferSize < 1) {
throw msg.parameterOutOfRange("bufferSize");
}
if (timeout < 0L) {
throw msg.parameterOutOfRange("timeout");
}
this.channel = channel;
buffer = ByteBuffer.allocate(bufferSize);
buffer.limit(0);
final long calcTimeout = unit.toNanos(timeout);
this.timeout = timeout == 0L ? 0L : calcTimeout < 1L ? 1L : calcTimeout;
}
private boolean enter() {
int old = flags;
do {
if (Bits.allAreSet(old, FLAG_ENTERED)) {
throw msg.concurrentAccess();
}
} while (! flagsUpdater.compareAndSet(this, old, old | FLAG_ENTERED));
return Bits.allAreSet(old, FLAG_EOF);
}
private void exit(boolean setEof) {
int oldFlags, newFlags;
do {
oldFlags = flags;
newFlags = oldFlags &~ FLAG_ENTERED;
if (setEof) {
newFlags |= FLAG_EOF;
}
} while (! flagsUpdater.compareAndSet(this, oldFlags, newFlags));
}
/**
* Get the read timeout.
*
* @param unit the time unit
* @return the timeout in the given unit
*/
public long getReadTimeout(TimeUnit unit) {
if (unit == null) {
throw msg.nullParameter("unit");
}
return unit.convert(timeout, TimeUnit.NANOSECONDS);
}
/**
* Set the read timeout. Does not affect read operations in progress.
*
* @param timeout the read timeout, or 0 for none
* @param unit the time unit
*/
public void setReadTimeout(long timeout, TimeUnit unit) {
if (timeout < 0L) {
throw msg.parameterOutOfRange("timeout");
}
if (unit == null) {
throw msg.nullParameter("unit");
}
final long calcTimeout = unit.toNanos(timeout);
this.timeout = timeout == 0L ? 0L : calcTimeout < 1L ? 1L : calcTimeout;
}
/**
* Read a byte, blocking if necessary.
*
* @return the byte read, or -1 if the end of the stream has been reached
* @throws IOException if an I/O error occurs
*/
public int read() throws IOException {
boolean eof = enter();
try {
final StreamSourceChannel channel = this.channel;
final ByteBuffer buffer = this.buffer;
// try buffer first
if (buffer.hasRemaining()) {
return buffer.get() & 0xff;
}
if (eof) {
return -1;
}
// fill buffer
int res;
long timeout;
long start = System.nanoTime();
long elapsed = 0L;
for (;;) {
buffer.clear();
try {
res = channel.read(buffer);
} finally {
buffer.flip();
}
if (res == -1) {
eof = true;
return -1;
}
if (res > 0) {
return buffer.get() & 0xff;
}
timeout = this.timeout;
if (timeout == 0L) {
channel.awaitReadable();
} else if (timeout < elapsed) {
throw msg.readTimeout();
} else {
channel.awaitReadable(timeout - elapsed, TimeUnit.NANOSECONDS);
}
elapsed = System.nanoTime() - start;
}
} finally {
exit(eof);
}
}
/**
* Read bytes into an array.
*
* @param b the destination array
* @param off the offset into the array at which bytes should be filled
* @param len the number of bytes to fill
* @return the number of bytes read, or -1 if the end of the stream has been reached
* @throws IOException if an I/O error occurs
*/
public int read(final byte[] b, int off, int len) throws IOException {
if (len < 1) {
return 0;
}
boolean eof = enter();
try {
int total = 0;
// empty buffer
final ByteBuffer buffer = this.buffer;
final ByteBuffer userBuffer = ByteBuffer.wrap(b, off, len);
if (buffer.hasRemaining()) {
total += Buffers.copy(userBuffer, buffer);
// either the user buffer is full, or the source buffer is empty
if (! userBuffer.hasRemaining()) {
return total;
}
}
// at this point the buffer is guaranteed to be empty
assert ! buffer.hasRemaining();
assert userBuffer.hasRemaining();
if (eof) return total == 0 ? -1 : total;
// read the rest directly into the user buffer
final StreamSourceChannel channel = this.channel;
long timeout;
long start = System.nanoTime();
long elapsed = 0L;
int res;
for (;;) {
res = channel.read(userBuffer);
if (res == -1) {
eof = true;
return total == 0 ? -1 : total;
}
total += res;
if (total > 0) {
return total;
}
timeout = this.timeout;
try {
if (timeout == 0L) {
channel.awaitReadable();
} else if (timeout < elapsed) {
throw msg.readTimeout();
} else {
channel.awaitReadable(timeout - elapsed, TimeUnit.NANOSECONDS);
}
} catch (InterruptedIOException e) {
e.bytesTransferred = total;
throw e;
}
elapsed = System.nanoTime() - start;
}
} finally {
exit(eof);
}
}
/**
* Skip bytes in the stream.
*
* @param n the number of bytes to skip
* @return the number of bytes skipped (0 if the end of stream has been reached)
* @throws IOException if an I/O error occurs
*/
public long skip(long n) throws IOException {
if (n < 1L) {
return 0L;
}
boolean eof = enter();
try {
// if we don't do this, InterruptedIOException might not be able to report a correct result
n = Math.min(n, (long)Integer.MAX_VALUE);
long total = 0L;
final ByteBuffer buffer = this.buffer;
if (buffer.hasRemaining()) {
final int cnt = (int) min(buffer.remaining(), n);
Buffers.skip(buffer, cnt);
total += cnt;
n -= cnt;
assert n == 0L || ! buffer.hasRemaining();
if (n == 0L) {
return total;
}
}
assert ! buffer.hasRemaining();
if (eof) {
return total;
}
long timeout;
long start = System.nanoTime();
long elapsed = 0L;
long res;
for (;;) {
if (n == 0L) return total;
res = Channels.drain(channel, n);
if (res == -1) {
return total;
} else if (res == 0) {
timeout = this.timeout;
try {
if (timeout == 0L) {
channel.awaitReadable();
} else if (timeout < elapsed) {
throw msg.readTimeout();
} else {
channel.awaitReadable(timeout - elapsed, TimeUnit.NANOSECONDS);
}
} catch (InterruptedIOException e) {
assert total < (long) Integer.MAX_VALUE;
e.bytesTransferred = (int) total;
throw e;
}
elapsed = System.nanoTime() - start;
} else {
total += res;
n -= res;
}
}
} finally {
exit(eof);
}
}
/**
* Return the number of bytes available to read, or 0 if a subsequent {@code read()} operation would block. If
* a 0 is returned, the channel's {@link org.xnio.channels.SuspendableReadChannel#resumeReads() resumeReads()} method may be used
* to register for read-readiness.
*
* @return the number of ready bytes, or 0 for none
* @throws IOException if an I/O error occurs
*/
public int available() throws IOException {
boolean eof = enter();
try {
final ByteBuffer buffer = this.buffer;
final int rem = buffer.remaining();
if (rem > 0 || eof) {
return rem;
}
buffer.clear();
try {
channel.read(buffer);
} catch (IOException e) {
throw e;
} finally {
buffer.flip();
}
return buffer.remaining();
} finally {
exit(eof);
}
}
/**
* Close the stream. Shuts down the channel's read side.
*
* @throws IOException if an I/O error occurs
*/
public void close() throws IOException {
enter();
try {
buffer.clear().flip();
channel.shutdownReads();
} finally {
exit(true);
}
}
}
