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/*
* Copyright 2013 Google Inc.
*
* 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.bitcoinj.net;
import org.bitcoinj.core.Message;
import org.bitcoinj.utils.Threading;
import com.google.common.base.Throwables;
import org.slf4j.LoggerFactory;
import javax.annotation.Nullable;
import javax.annotation.concurrent.GuardedBy;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.CancelledKeyException;
import java.nio.channels.SelectionKey;
import java.nio.channels.SocketChannel;
import java.util.Arrays;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Set;
import java.util.concurrent.locks.ReentrantLock;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
// TODO: The locking in all this class is horrible and not really necessary. We should just run all network stuff on one thread.
/**
* A simple NIO MessageWriteTarget which handles all the business logic of a connection (reading+writing bytes).
* Used only by the NioClient and NioServer classes
*/
class ConnectionHandler implements MessageWriteTarget {
private static final org.slf4j.Logger log = LoggerFactory.getLogger(ConnectionHandler.class);
private static final int BUFFER_SIZE_LOWER_BOUND = 4096;
private static final int BUFFER_SIZE_UPPER_BOUND = 65536;
private static final int OUTBOUND_BUFFER_BYTE_COUNT = Message.MAX_SIZE + 24; // 24 byte message header
// We lock when touching local flags and when writing data, but NEVER when calling any methods which leave this
// class into non-Java classes.
private final ReentrantLock lock = Threading.lock("nioConnectionHandler");
@GuardedBy("lock") private final ByteBuffer readBuff;
@GuardedBy("lock") private final SocketChannel channel;
@GuardedBy("lock") private final SelectionKey key;
@GuardedBy("lock") StreamConnection connection;
@GuardedBy("lock") private boolean closeCalled = false;
@GuardedBy("lock") private long bytesToWriteRemaining = 0;
@GuardedBy("lock") private final LinkedList bytesToWrite = new LinkedList();
private Set connectedHandlers;
public ConnectionHandler(StreamConnectionFactory connectionFactory, SelectionKey key) throws IOException {
this(connectionFactory.getNewConnection(((SocketChannel) key.channel()).socket().getInetAddress(), ((SocketChannel) key.channel()).socket().getPort()), key);
if (connection == null)
throw new IOException("Parser factory.getNewConnection returned null");
}
private ConnectionHandler(@Nullable StreamConnection connection, SelectionKey key) {
this.key = key;
this.channel = checkNotNull(((SocketChannel)key.channel()));
if (connection == null) {
readBuff = null;
return;
}
this.connection = connection;
readBuff = ByteBuffer.allocateDirect(Math.min(Math.max(connection.getMaxMessageSize(), BUFFER_SIZE_LOWER_BOUND), BUFFER_SIZE_UPPER_BOUND));
connection.setWriteTarget(this); // May callback into us (eg closeConnection() now)
connectedHandlers = null;
}
public ConnectionHandler(StreamConnection connection, SelectionKey key, Set connectedHandlers) {
this(checkNotNull(connection), key);
// closeConnection() may have already happened because we invoked the other c'tor above, which called
// connection.setWriteTarget which might have re-entered already. In this case we shouldn't add ourselves
// to the connectedHandlers set.
lock.lock();
try {
this.connectedHandlers = connectedHandlers;
if (!closeCalled)
checkState(this.connectedHandlers.add(this));
} finally {
lock.unlock();
}
}
@GuardedBy("lock")
private void setWriteOps() {
// Make sure we are registered to get updated when writing is available again
key.interestOps(key.interestOps() | SelectionKey.OP_WRITE);
// Refresh the selector to make sure it gets the new interestOps
key.selector().wakeup();
}
// Tries to write any outstanding write bytes, runs in any thread (possibly unlocked)
private void tryWriteBytes() throws IOException {
lock.lock();
try {
// Iterate through the outbound ByteBuff queue, pushing as much as possible into the OS' network buffer.
Iterator bytesIterator = bytesToWrite.iterator();
while (bytesIterator.hasNext()) {
ByteBuffer buff = bytesIterator.next();
bytesToWriteRemaining -= channel.write(buff);
if (!buff.hasRemaining())
bytesIterator.remove();
else {
setWriteOps();
break;
}
}
// If we are done writing, clear the OP_WRITE interestOps
if (bytesToWrite.isEmpty())
key.interestOps(key.interestOps() & ~SelectionKey.OP_WRITE);
// Don't bother waking up the selector here, since we're just removing an op, not adding
} finally {
lock.unlock();
}
}
@Override
public void writeBytes(byte[] message) throws IOException {
boolean andUnlock = true;
lock.lock();
try {
// Network buffers are not unlimited (and are often smaller than some messages we may wish to send), and
// thus we have to buffer outbound messages sometimes. To do this, we use a queue of ByteBuffers and just
// append to it when we want to send a message. We then let tryWriteBytes() either send the message or
// register our SelectionKey to wakeup when we have free outbound buffer space available.
if (bytesToWriteRemaining + message.length > OUTBOUND_BUFFER_BYTE_COUNT)
throw new IOException("Outbound buffer overflowed");
// Just dump the message onto the write buffer and call tryWriteBytes
// TODO: Kill the needless message duplication when the write completes right away
bytesToWrite.offer(ByteBuffer.wrap(Arrays.copyOf(message, message.length)));
bytesToWriteRemaining += message.length;
setWriteOps();
} catch (IOException e) {
lock.unlock();
andUnlock = false;
log.warn("Error writing message to connection, closing connection", e);
closeConnection();
throw e;
} catch (CancelledKeyException e) {
lock.unlock();
andUnlock = false;
log.warn("Error writing message to connection, closing connection", e);
closeConnection();
throw new IOException(e);
} finally {
if (andUnlock)
lock.unlock();
}
}
// May NOT be called with lock held
@Override
public void closeConnection() {
checkState(!lock.isHeldByCurrentThread());
try {
channel.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
connectionClosed();
}
private void connectionClosed() {
boolean callClosed = false;
lock.lock();
try {
callClosed = !closeCalled;
closeCalled = true;
} finally {
lock.unlock();
}
if (callClosed) {
checkState(connectedHandlers == null || connectedHandlers.remove(this));
connection.connectionClosed();
}
}
// Handle a SelectionKey which was selected
// Runs unlocked as the caller is single-threaded (or if not, should enforce that handleKey is only called
// atomically for a given ConnectionHandler)
public static void handleKey(SelectionKey key) {
ConnectionHandler handler = ((ConnectionHandler)key.attachment());
try {
if (handler == null)
return;
if (!key.isValid()) {
handler.closeConnection(); // Key has been cancelled, make sure the socket gets closed
return;
}
if (key.isReadable()) {
// Do a socket read and invoke the connection's receiveBytes message
int read = handler.channel.read(handler.readBuff);
if (read == 0)
return; // Was probably waiting on a write
else if (read == -1) { // Socket was closed
key.cancel();
handler.closeConnection();
return;
}
// "flip" the buffer - setting the limit to the current position and setting position to 0
handler.readBuff.flip();
// Use connection.receiveBytes's return value as a check that it stopped reading at the right location
int bytesConsumed = checkNotNull(handler.connection).receiveBytes(handler.readBuff);
checkState(handler.readBuff.position() == bytesConsumed);
// Now drop the bytes which were read by compacting readBuff (resetting limit and keeping relative
// position)
handler.readBuff.compact();
}
if (key.isWritable())
handler.tryWriteBytes();
} catch (Exception e) {
// This can happen eg if the channel closes while the thread is about to get killed
// (ClosedByInterruptException), or if handler.connection.receiveBytes throws something
Throwable t = Throwables.getRootCause(e);
log.warn("Error handling SelectionKey: {}", t.getMessage() != null ? t.getMessage() : t.getClass().getName());
handler.closeConnection();
}
}
}
