com.google.bitcoin.net.NioClientManager Maven / Gradle / Ivy
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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 com.google.bitcoin.net;
import com.google.common.base.Throwables;
import com.google.common.util.concurrent.AbstractExecutionThreadService;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.net.SocketAddress;
import java.nio.channels.*;
import java.nio.channels.spi.SelectorProvider;
import java.util.*;
import java.util.concurrent.LinkedBlockingQueue;
/**
* A class which manages a set of client connections. Uses Java NIO to select network events and processes them in a
* single network processing thread.
*/
public class NioClientManager extends AbstractExecutionThreadService implements ClientConnectionManager {
private static final org.slf4j.Logger log = LoggerFactory.getLogger(NioClientManager.class);
private final Selector selector;
// SocketChannels and StreamParsers of newly-created connections which should be registered with OP_CONNECT
class SocketChannelAndParser {
SocketChannel sc; StreamParser parser;
SocketChannelAndParser(SocketChannel sc, StreamParser parser) { this.sc = sc; this.parser = parser; }
}
final Queue newConnectionChannels = new LinkedBlockingQueue();
// Added to/removed from by the individual ConnectionHandler's, thus must by synchronized on its own.
private final Set connectedHandlers = Collections.synchronizedSet(new HashSet());
// Handle a SelectionKey which was selected
private void handleKey(SelectionKey key) throws IOException {
// We could have a !isValid() key here if the connection is already closed at this point
if (key.isValid() && key.isConnectable()) { // ie a client connection which has finished the initial connect process
// Create a ConnectionHandler and hook everything together
StreamParser parser = (StreamParser) key.attachment();
SocketChannel sc = (SocketChannel) key.channel();
ConnectionHandler handler = new ConnectionHandler(parser, key, connectedHandlers);
try {
if (sc.finishConnect()) {
log.info("Successfully connected to {}", sc.socket().getRemoteSocketAddress());
key.interestOps(SelectionKey.OP_READ).attach(handler);
handler.parser.connectionOpened();
} else {
log.error("Failed to connect to {}", sc.socket().getRemoteSocketAddress());
handler.closeConnection(); // Failed to connect for some reason
}
} catch (Exception e) {
// If e is a CancelledKeyException, there is a race to get to interestOps after finishConnect() which
// may cause this. Otherwise it may be any arbitrary kind of connection failure.
// Calling sc.socket().getRemoteSocketAddress() here throws an exception, so we can only log the error itself
log.error("Failed to connect with exception: {}", Throwables.getRootCause(e).getMessage());
handler.closeConnection();
}
} else // Process bytes read
ConnectionHandler.handleKey(key);
}
/**
* Creates a new client manager which uses Java NIO for socket management. Uses a single thread to handle all select
* calls.
*/
public NioClientManager() {
try {
selector = SelectorProvider.provider().openSelector();
} catch (IOException e) {
throw new RuntimeException(e); // Shouldn't ever happen
}
}
@Override
public void run() {
try {
Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
while (isRunning()) {
SocketChannelAndParser conn;
while ((conn = newConnectionChannels.poll()) != null) {
try {
SelectionKey key = conn.sc.register(selector, SelectionKey.OP_CONNECT);
key.attach(conn.parser);
} catch (ClosedChannelException e) {
log.info("SocketChannel was closed before it could be registered");
}
}
selector.select();
Iterator keyIterator = selector.selectedKeys().iterator();
while (keyIterator.hasNext()) {
SelectionKey key = keyIterator.next();
keyIterator.remove();
handleKey(key);
}
}
} catch (Exception e) {
log.error("Error trying to open/read from connection: ", e);
} finally {
// Go through and close everything, without letting IOExceptions get in our way
for (SelectionKey key : selector.keys()) {
try {
key.channel().close();
} catch (IOException e) {
log.error("Error closing channel", e);
}
key.cancel();
if (key.attachment() instanceof ConnectionHandler)
ConnectionHandler.handleKey(key); // Close connection if relevant
}
try {
selector.close();
} catch (IOException e) {
log.error("Error closing client manager selector", e);
}
}
}
@Override
public void openConnection(SocketAddress serverAddress, StreamParser parser) {
if (!isRunning())
throw new IllegalStateException();
// Create a new connection, give it a parser as an attachment
try {
SocketChannel sc = SocketChannel.open();
sc.configureBlocking(false);
sc.connect(serverAddress);
newConnectionChannels.offer(new SocketChannelAndParser(sc, parser));
selector.wakeup();
} catch (IOException e) {
log.error("Could not connect to " + serverAddress);
throw new RuntimeException(e); // This should only happen if we are, eg, out of system resources
}
}
@Override
public void triggerShutdown() {
selector.wakeup();
}
@Override
public int getConnectedClientCount() {
return connectedHandlers.size();
}
@Override
public void closeConnections(int n) {
while (n-- > 0) {
ConnectionHandler handler;
synchronized (connectedHandlers) {
handler = connectedHandlers.iterator().next();
}
if (handler != null)
handler.closeConnection(); // Removes handler from connectedHandlers before returning
}
}
}