Java tutorial
/* dCache - http://www.dcache.org/ * * Copyright (C) 2015 Deutsches Elektronen-Synchrotron * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero 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 Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package org.dcache.xrootd.door; import com.google.common.util.concurrent.ListenableFuture; import com.google.common.util.concurrent.ListeningExecutorService; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelPromise; import io.netty.channel.ChannelPromiseNotifier; import java.util.Collections; import java.util.HashSet; import java.util.Set; import java.util.concurrent.ExecutorService; import java.util.concurrent.Future; import dmg.cells.nucleus.CDC; import org.dcache.util.CDCListeningExecutorServiceDecorator; import org.dcache.xrootd.AbstractXrootdRequestHandler; import org.dcache.xrootd.protocol.messages.XrootdRequest; /** * Subclass of AbstractXrootdRequestHandler that dispatches calls to doOnXXX methods * from a supplied executor. * * Ensures that the CDC survives the thread boundaries. */ public class ConcurrentXrootdRequestHandler extends AbstractXrootdRequestHandler { protected final ListeningExecutorService _executor; /** * The set of requests which are currently processed for this channel. They * will be interrupted in case the channel is disconnected. */ private final Set<Future<?>> _requests = Collections.synchronizedSet(new HashSet<>()); public ConcurrentXrootdRequestHandler(ExecutorService executor) { _executor = new CDCListeningExecutorServiceDecorator(executor); } @Override protected ChannelFuture respond(ChannelHandlerContext ctx, Object response) { CDC cdc = new CDC(); ChannelPromise promise = ctx.newPromise(); ctx.executor().execute(() -> { try (CDC ignored = cdc.restore()) { ctx.writeAndFlush(response).addListener(future -> { if (!future.isSuccess()) { exceptionCaught(ctx, future.cause()); } }).addListener(new ChannelPromiseNotifier(promise)); } }); return promise; } @Override protected void requestReceived(ChannelHandlerContext ctx, XrootdRequest req) { ListenableFuture<?> future = _executor.submit(() -> super.requestReceived(ctx, req)); _requests.add(future); future.addListener(() -> _requests.remove(future), _executor); } @Override public void channelInactive(ChannelHandlerContext ctx) throws Exception { synchronized (_requests) { for (Future<?> request : _requests) { request.cancel(true); } } } }