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net.sf.hajdbc.distributed.jgroups.JGroupsCommandDispatcher Maven / Gradle / Ivy
/*
* HA-JDBC: High-Availability JDBC
* Copyright (C) 2012 Paul Ferraro
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see the execution context type
*/
public class JGroupsCommandDispatcher implements RequestHandler, CommandDispatcher, org.jgroups.MembershipListener, MessageListener
{
private final Logger logger = LoggerFactory.getLogger(this.getClass());
private final String id;
private final long timeout;
private final MessageDispatcher dispatcher;
private final C context;
private final AtomicReference viewReference = new AtomicReference();
private final MembershipListener membershipListener;
private final Stateful stateful;
private final LockService lockService;
/**
* Constructs a new ChannelCommandDispatcher.
* @param id the channel name
* @param channel a JGroups channel
* @param timeout the command timeout
* @param context the execution context
* @param stateful the state transfer handler
* @param membershipListener notified of membership changes
* @throws Exception if channel cannot be created
*/
public JGroupsCommandDispatcher(String id, Channel channel, long timeout, C context, Stateful stateful, MembershipListener membershipListener) throws Exception
{
this.id = id;
this.context = context;
this.stateful = stateful;
this.membershipListener = membershipListener;
this.lockService = new LockService(channel);
this.dispatcher = new MessageDispatcher( channel, this, this, this);
this.timeout = timeout;
}
public LockService getLockService() {
return lockService;
}
/**
* {@inheritDoc}
* @see net.sf.hajdbc.Lifecycle#start()
*/
@Override
public void start() throws Exception
{
Channel channel = this.dispatcher.getChannel();
channel.setDiscardOwnMessages(false);
// Connect and fetch state
int failCount = 0;
boolean connected = false;
while(!connected) {
try {
channel.connect(this.id, null, 2000);
connected = true;
}catch (Exception e){
failCount++;
if(failCount>=5){
throw e;
}
}
}
}
/**
* {@inheritDoc}
* @see net.sf.hajdbc.Lifecycle#stop()
*/
@Override
public void stop()
{
Channel channel = this.dispatcher.getChannel();
if (channel.isOpen())
{
if (channel.isConnected())
{
channel.disconnect();
}
channel.close();
}
}
@Override
public Map executeAll(Command command, Member... excludedMembers)
{
Message message = new Message(null, this.getLocalAddress(), Objects.serialize(command));
RequestOptions options = new RequestOptions(ResponseMode.GET_ALL, this.timeout);
if ((excludedMembers != null) && (excludedMembers.length > 0))
{
Address[] exclusions = new Address[excludedMembers.length];
for (int i = 0; i < excludedMembers.length; ++i)
{
exclusions[i] = ((AddressMember) excludedMembers[i]).getAddress();
}
options.setExclusionList(exclusions);
}
try
{
Map> responses = this.dispatcher.castMessage(null, message, options);
if (responses == null) return Collections.emptyMap();
Map results = new TreeMap();
for (Map.Entry> entry: responses.entrySet())
{
Rsp response = entry.getValue();
results.put(new AddressMember(entry.getKey()), response.wasReceived() ? response.getValue() : null);
}
return results;
}
catch (Exception e)
{
return null;
}
}
/**
* {@inheritDoc}
* @see net.sf.hajdbc.distributed.CommandDispatcher#execute(Command, Member)
*/
@Override
public R execute(Command command, Member member)
{
Message message = new Message(((AddressMember) member).getAddress(), this.getLocalAddress(), Objects.serialize(command));
try
{
return this.dispatcher.sendMessage(message, new RequestOptions(ResponseMode.GET_ALL, this.timeout));
}
catch (Exception e)
{
this.logger.log(Level.WARN, e);
return null;
}
}
/**
* {@inheritDoc}
* @see net.sf.hajdbc.distributed.CommandDispatcher#getLocal()
*/
@Override
public AddressMember getLocal()
{
return new AddressMember(this.getLocalAddress());
}
private Address getLocalAddress()
{
return this.dispatcher.getChannel().getAddress();
}
/**
* {@inheritDoc}
* @see net.sf.hajdbc.distributed.CommandDispatcher#getCoordinator()
*/
@Override
public AddressMember getCoordinator()
{
return new AddressMember(this.getCoordinatorAddress());
}
private Address getCoordinatorAddress()
{
return this.dispatcher.getChannel().getView().getMembers().get(0);
}
/**
* {@inheritDoc}
* @see org.jgroups.blocks.RequestHandler#handle(org.jgroups.Message)
*/
@Override
public Object handle(Message message)
{
Command command = Objects.deserialize(message.getRawBuffer());
this.logger.log(Level.DEBUG, Messages.COMMAND_RECEIVED.getMessage(command, message.getSrc()));
return command.execute(this.context);
}
/**
* {@inheritDoc}
* @see org.jgroups.MembershipListener#viewAccepted(org.jgroups.View)
*/
@Override
public void viewAccepted(View view)
{
if(view instanceof MergeView) {
new Thread() {
public void run() {
lockService.unlockAll();
// stop all access to resources protected by l1, l2 or l3
// every thread needs to re-acquire the locks it holds
}
}.start();
}
if (this.membershipListener != null)
{
View oldView = this.viewReference.getAndSet(view);
for (Address address: view.getMembers())
{
if ((oldView == null) || !oldView.containsMember(address))
{
this.membershipListener.added(new AddressMember(address));
}
}
if (oldView != null)
{
for (Address address: oldView.getMembers())
{
if (!view.containsMember(address))
{
this.membershipListener.removed(new AddressMember(address));
}
}
}
}
}
/**
* {@inheritDoc}
* @see org.jgroups.MessageListener#getState(java.io.OutputStream)
*/
@Override
public void getState(OutputStream output) throws Exception
{
ObjectOutput out = new ObjectOutputStream(output);
this.stateful.writeState(out);
out.flush();
}
/**
* {@inheritDoc}
* @see org.jgroups.MessageListener#setState(java.io.InputStream)
*/
@Override
public void setState(InputStream input) throws Exception
{
this.stateful.readState(new ObjectInputStream(input));
}
/**
* {@inheritDoc}
* @see org.jgroups.MembershipListener#suspect(org.jgroups.Address)
*/
@Override
public void suspect(Address member)
{
}
/**
* {@inheritDoc}
* @see org.jgroups.MembershipListener#block()
*/
@Override
public void block()
{
}
/**
* {@inheritDoc}
* @see org.jgroups.MembershipListener#unblock()
*/
@Override
public void unblock()
{
}
/**
* {@inheritDoc}
* @see org.jgroups.MessageListener#receive(org.jgroups.Message)
*/
@Override
public void receive(Message message)
{
}
}
