/*
* Copyright 2009-2010 Brian S O'Neill
*
* 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.cojen.dirmi.io;
import java.io.EOFException;
import java.io.InputStream;
import java.io.IOException;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
import org.cojen.dirmi.ClosedException;
import org.cojen.dirmi.RejectedException;
/**
* Buffered InputStream which is paired with {@link PacketOutputStream}.
*
* @author Brian S O'Neill
*/
abstract class PacketInputStream<P extends PacketInputStream<P>> extends ChannelInputStream {
private static final AtomicReferenceFieldUpdater<PacketInputStream, InputStream> inUpdater =
AtomicReferenceFieldUpdater
.newUpdater(PacketInputStream.class, InputStream.class, "mIn");
static final int DEFAULT_SIZE = 8192;
volatile InputStream mIn;
byte[] mBuffer;
int mStart;
int mEnd;
/* Special values:
0: need to read next packet header
-1: ready to be recycled
-2: cannot be recycled
*/
private int mPacketSize;
public PacketInputStream(InputStream in) {
this(in, DEFAULT_SIZE);
}
public PacketInputStream(InputStream in, int size) {
mIn = in;
synchronized (this) {
mBuffer = new byte[size];
}
}
protected PacketInputStream() {
}
@Override
public int read() throws IOException {
try {
synchronized (this) {
InputStream in = in();
int packetSize = mPacketSize;
if (packetSize < 0) {
return -1;
}
byte[] buffer = mBuffer;
int b = readFrom(in, buffer);
if (b < 0) {
mPacketSize = -2;
return b;
}
if (--packetSize >= 0) {
mPacketSize = packetSize;
return b;
}
if (b == 0) {
mPacketSize = -1;
return -1;
}
int b2 = readFrom(in, buffer);
if (b2 < 0) {
mPacketSize = -2;
return -1;
}
if (b < 128) {
mPacketSize = b - 1;
return b2;
}
int b3 = readFrom(in, buffer);
if (b3 < 0) {
mPacketSize = -2;
return -1;
}
mPacketSize = (((b & 0x7f) << 8) | b2) + (0x80 - 1);
return b3;
}
} catch (IOException e) {
disconnect();
throw e;
}
}
/**
* Low level read that ignores packet info. Caller must be synchronized.
*/
private int readFrom(InputStream in, byte[] buffer) throws IOException {
if (buffer == null) {
// Buffer can be null if disconnected.
throw new ClosedException();
}
int start = mStart;
if (mEnd - start > 0) {
mStart = start + 1;
return buffer[start] & 0xff;
} else {
int amt = in.read(buffer, 0, buffer.length);
if (amt <= 0) {
return -1;
} else {
mStart = 1;
mEnd = amt;
return buffer[0] & 0xff;
}
}
}
@Override
public int read(byte[] b, int off, int len) throws IOException {
try {
synchronized (this) {
InputStream in = in();
byte[] buffer = mBuffer;
int packetSize = mPacketSize;
if (packetSize <= 0) {
if (packetSize < 0) {
return -1;
}
int b1 = readFrom(in, buffer);
if (b1 <= 0) {
mPacketSize = b1 == 0 ? -1 : -2;
return -1;
}
if (b1 < 128) {
packetSize = b1;
} else {
int b2 = readFrom(in, buffer);
if (b2 < 0) {
mPacketSize = -2;
return -1;
}
packetSize = (((b1 & 0x7f) << 8) | b2) + 0x80;
}
}
int amt = readFrom(in, buffer, b, off, len > packetSize ? packetSize : len);
if (amt < 0) {
mPacketSize = -2;
return -1;
}
mPacketSize = packetSize - amt;
return amt;
}
} catch (IOException e) {
disconnect();
throw e;
}
}
/**
* Low level read that ignores packet info. Caller must be synchronized.
*/
private int readFrom(InputStream in, byte[] buffer, byte[] b, int off, int len)
throws IOException
{
int start = mStart;
int avail = mEnd - start;
if (avail >= len) {
System.arraycopy(buffer, start, b, off, len);
mStart = start + len;
return len;
} else {
System.arraycopy(buffer, start, b, off, avail);
mStart = 0;
mEnd = 0;
off += avail;
len -= avail;
try {
// Avoid a blocking read.
if (avail > 0 && (len = Math.min(len, in.available())) <= 0) {
return avail;
}
if (len >= buffer.length) {
int amt = in.read(b, off, len);
return amt <= 0 ? (avail <= 0 ? -1 : avail) : (avail + amt);
} else {
int amt = in.read(buffer, 0, buffer.length);
if (amt <= 0) {
return avail <= 0 ? -1 : avail;
} else {
int fill = Math.min(amt, len);
System.arraycopy(buffer, 0, b, off, fill);
mStart = fill;
mEnd = amt;
return avail + fill;
}
}
} catch (IOException e) {
if (avail > 0) {
// Return what we have and postpone exception for later.
return avail;
}
throw e;
}
}
}
@Override
public long skip(long n) throws IOException {
try {
synchronized (this) {
InputStream in = in();
if (n <= 0) {
return 0;
}
if (n > Integer.MAX_VALUE) {
n = Integer.MAX_VALUE;
}
return skip(in, (int) n);
}
} catch (IOException e) {
disconnect();
throw e;
}
}
private int skip(InputStream in, int n) throws IOException {
int packetSize = mPacketSize;
if (packetSize <= 0) {
if (packetSize < 0) {
return 0;
}
int b1 = readFrom(in, mBuffer);
if (b1 <= 0) {
mPacketSize = b1 == 0 ? -1 : -2;
return 0;
}
if (b1 < 128) {
packetSize = b1;
} else {
int b2 = readFrom(in, mBuffer);
if (b2 < 0) {
mPacketSize = -2;
return 0;
}
packetSize = (((b1 & 0x7f) << 8) | b2) + 0x80;
}
}
if (n > packetSize) {
n = packetSize;
}
int amt = mEnd - mStart;
if (amt <= 0) {
if ((n = (int) in.skip(n)) <= 0) {
mPacketSize = -2;
return 0;
}
} else {
if (n > amt) {
n = amt;
}
mStart += n;
}
mPacketSize = packetSize - n;
return n;
}
/**
* @return false if more to drain; true does not imply that stream was recycled
*/
boolean drain(InputStream in, int amount) {
byte[] buffer;
int start, end;
try {
synchronized (this) {
while (skip(in, amount) > 0);
if (mPacketSize != -1) {
return mPacketSize < -1;
}
if ((buffer = mBuffer) == null) {
return true;
}
start = mStart;
end = mEnd;
}
} catch (IOException e) {
try {
in.close();
} catch (IOException e2) {
// Ignore.
}
return true;
}
P recycled = newInstance();
synchronized (recycled) {
recycled.mIn = in;
recycled.mBuffer = buffer;
recycled.mStart = start;
recycled.mEnd = end;
}
recycled(recycled);
return true;
}
@Override
public int available() throws IOException {
// Without accounting for encoded packet sizes, the available amount
// would be reported as too high. So don't bother figuring it out.
in(); // check if closed
return 0;
}
@Override
public boolean isReady() throws IOException {
try {
synchronized (this) {
InputStream in = in();
return mPacketSize >= 0 && ((mEnd - mStart) > 0 || in.available() > 0);
}
} catch (IOException e) {
disconnect();
throw e;
}
}
/**
* Sets the size of the buffer, returning the actual size applied.
*/
@Override
public synchronized int setBufferSize(int size) {
if (size < 1) {
throw new IllegalArgumentException("Buffer too small: " + size);
}
byte[] buffer = mBuffer;
if (buffer == null) {
return 0;
}
int avail = mEnd - mStart;
if (size < buffer.length) {
size = Math.max(size, avail);
}
if (size != buffer.length) {
byte[] newBuffer = new byte[size];
System.arraycopy(buffer, mStart, newBuffer, 0, avail);
mBuffer = newBuffer;
mStart = 0;
mEnd = avail;
}
return size;
}
/**
* Ensures at least one byte can be read, blocking if necessary.
*
* @throws EOFException if nothing left to read
*/
void fill() throws IOException {
try {
synchronized (this) {
InputStream in = in();
byte[] buffer = mBuffer;
if (buffer == null) {
throw new ClosedException();
}
int avail = mEnd - mStart;
if (avail == 0) {
int amt = in.read(buffer, 0, buffer.length);
if (amt <= 0) {
throw new EOFException();
}
mStart = 0;
mEnd = amt;
}
}
} catch (IOException e) {
disconnect();
throw e;
}
}
@Override
void inputNotify(IOExecutor executor, final Channel.Listener listener) {
try {
executor.execute(new Runnable() {
public void run() {
try {
fill();
listener.ready();
} catch (IOException e) {
listener.closed(e);
}
}
});
} catch (RejectedException e) {
listener.rejected(e);
}
}
@Override
public void close() throws IOException {
inputClose();
}
@Override
public void disconnect() {
inputDisconnect();
}
@Override
public synchronized boolean inputResume() {
if (mIn == null) {
return false;
}
// Peek ahead and consume EOF if possible.
if (mPacketSize == 0 && (mEnd - mStart) > 0 && mBuffer[mStart] == 0) {
try {
read();
} catch (IOException e) {
return false;
}
}
if (mPacketSize != -1) {
return false;
}
mPacketSize = 0;
return true;
}
@Override
public boolean isResumeSupported() {
return true;
}
@Override
final void inputClose() throws IOException {
final InputStream in = inUpdater.getAndSet(this, null);
if (in == null) {
return;
}
doRecycle: {
byte[] buffer;
int start, end;
synchronized (this) {
int packetSize = mPacketSize;
if (packetSize < -1) {
// Cannot recycle.
break doRecycle;
}
if (packetSize >= 0) {
try {
executor().execute(new Runnable() {
public void run() {
drain(in, Integer.MAX_VALUE);
}
});
return;
} catch (RejectedException e) {
// Cannot recycle.
break doRecycle;
}
}
if ((buffer = mBuffer) == null) {
break doRecycle;
}
mBuffer = null;
start = mStart;
end = mEnd;
}
P recycled = newInstance();
synchronized (recycled) {
recycled.mIn = in;
recycled.mBuffer = buffer;
recycled.mStart = start;
recycled.mEnd = end;
}
recycled(recycled);
return;
}
try {
in.close();
} finally {
// Lazily release buffer (no synchronized access)
mBuffer = null;
}
}
@Override
final void inputDisconnect() {
InputStream in = inUpdater.getAndSet(this, null);
if (in == null) {
return;
}
try {
try {
in.close();
} catch (IOException e) {
// Ignore.
}
} finally {
// Lazily release buffer (no synchronized access)
mBuffer = null;
}
}
/**
* Return an executor for asynchronously draining unread bytes when
* stream is closed.
*/
protected abstract IOExecutor executor();
/**
* Return a new instance, which will be used for recycling.
*/
protected abstract P newInstance();
/**
* Called by close method or by a separate thread when stream can be
* recycled.
*/
protected abstract void recycled(P newInstance);
private InputStream in() throws ClosedException {
InputStream in = mIn;
if (in == null) {
throw new ClosedException();
}
return in;
}
}