/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.activemq.transport;

import java.io.IOException;
import java.net.Socket;
import java.util.Iterator;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.activemq.transport.tcp.TimeStampStream;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This filter implements write timeouts for socket write operations.
 * When using blocking IO, the Java implementation doesn't have an explicit flag
 * to set a timeout, and can cause operations to block forever (or until the TCP stack implementation times out the retransmissions,
 * which is usually around 13-30 minutes).<br/>
 * To enable this transport, in the transport URI, simpley add<br/>
 * <code>transport.soWriteTimeout=<value in millis></code>.<br/>
 * For example (15 second timeout on write operations to the socket):</br>
 * <pre><code>
 * &lt;transportConnector
 *     name=&quot;tcp1&quot;
 *     uri=&quot;tcp://127.0.0.1:61616?transport.soTimeout=10000&amp;transport.soWriteTimeout=15000"
 * /&gt;
 * </code></pre><br/>
 * For example (enable default timeout on the socket):</br>
 * <pre><code>
 * &lt;transportConnector
 *     name=&quot;tcp1&quot;
 *     uri=&quot;tcp://127.0.0.1:61616?transport.soTimeout=10000&amp;transport.soWriteTimeout=15000"
 * /&gt;
 * </code></pre>
 *
 *
 */
public class WriteTimeoutFilter extends TransportFilter {

    private static final Logger LOG = LoggerFactory.getLogger(WriteTimeoutFilter.class);
    protected static ConcurrentLinkedQueue<WriteTimeoutFilter> writers = new ConcurrentLinkedQueue<WriteTimeoutFilter>();
    protected static AtomicInteger messageCounter = new AtomicInteger(0);
    protected static TimeoutThread timeoutThread = new TimeoutThread();

    protected static long sleep = 5000l;

    protected long writeTimeout = -1;

    public WriteTimeoutFilter(Transport next) {
        super(next);
    }

    @Override
    public void oneway(Object command) throws IOException {
        try {
            registerWrite(this);
            super.oneway(command);
        } catch (IOException x) {
            throw x;
        } finally {
            deRegisterWrite(this,false,null);
        }
    }

    public long getWriteTimeout() {
        return writeTimeout;
    }

    public void setWriteTimeout(long writeTimeout) {
        this.writeTimeout = writeTimeout;
    }

    public static long getSleep() {
        return sleep;
    }

    public static void setSleep(long sleep) {
        WriteTimeoutFilter.sleep = sleep;
    }


    protected TimeStampStream getWriter() {
        return next.narrow(TimeStampStream.class);
    }

    protected Socket getSocket() {
        return next.narrow(Socket.class);
    }

    protected static void registerWrite(WriteTimeoutFilter filter) {
        writers.add(filter);
    }

    protected static boolean deRegisterWrite(WriteTimeoutFilter filter, boolean fail, IOException iox) {
        boolean result = writers.remove(filter);
        if (result) {
            if (fail) {
                String message = "Forced write timeout for:"+filter.getNext().getRemoteAddress();
                LOG.warn(message);
                Socket sock = filter.getSocket();
                if (sock==null) {
                    LOG.error("Destination socket is null, unable to close socket.("+message+")");
                } else {
                    try {
                        sock.close();
                    }catch (IOException ignore) {
                    }
                }
            }
        }
        return result;
    }

    @Override
    public void start() throws Exception {
        try {
            registerWrite(this);
            super.start();
        } finally {
            deRegisterWrite(this, false, null);
        }
    }

    @Override
    public void stop() throws Exception {
        super.stop();
    }

    protected static class TimeoutThread extends Thread {
        static AtomicInteger instance = new AtomicInteger(0);
        boolean run = true;
        public TimeoutThread() {
            setName("WriteTimeoutFilter-Timeout-"+instance.incrementAndGet());
            setDaemon(true);
            setPriority(Thread.MIN_PRIORITY);
            start();
        }


        public void run() {
            while (run) {
                boolean error = false;
                try {
                    if (!interrupted()) {
                        Iterator<WriteTimeoutFilter> filters = writers.iterator();
                        while (run && filters.hasNext()) {
                            WriteTimeoutFilter filter = filters.next();
                            if (filter.getWriteTimeout()<=0) continue; //no timeout set
                            TimeStampStream writer = filter.getWriter();
                            if (writer == null) continue; //stream not yet initialized
                            long writeStart = writer.getWriteTimestamp();
                            long delta = (writer.isWriting() && writeStart>0)?System.currentTimeMillis() - writeStart:-1;
                            if (delta>filter.getWriteTimeout()) {
                                WriteTimeoutFilter.deRegisterWrite(filter, true,null);
                            }//if timeout
                        }//while
                    }//if interrupted
                    try {
                        Thread.sleep(getSleep());
                        error = false;
                    } catch (InterruptedException x) {
                        //do nothing
                    }
                }catch (Throwable t) { //make sure this thread never dies
                    if (!error) { //use error flag to avoid filling up the logs
                        LOG.error("WriteTimeout thread unable validate existing sockets.",t);
                        error = true;
                    }
                }
            }
        }
    }

}
