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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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package com.sun.tools.sjavac.server;

import com.sun.tools.sjavac.Log;

import java.io.IOException;
import java.util.Timer;
import java.util.TimerTask;

Monitors the presence of a port file and shuts down the given SjavacServer
whenever the port file is deleted or invalidated.
TODO: JDK-8046882
 
This is NOT part of any supported API.
 If you write code that depends on this, you do so at your own risk.
 This code and its internal interfaces are subject to change or
 deletion without notice.
/**
 * Monitors the presence of a port file and shuts down the given SjavacServer
 * whenever the port file is deleted or invalidated.
 *
 * TODO: JDK-8046882
 *
 *  <p><b>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */
public class PortFileMonitor {

    // Check if the portfile is gone, every 5 seconds.
    private final static int CHECK_PORTFILE_INTERVAL = 5000;

    final private Timer timer = new Timer();
    final private PortFile portFile;
    final private SjavacServer server;

    public PortFileMonitor(PortFile portFile,
                           SjavacServer server) {
        this.portFile = portFile;
        this.server = server;
    }

    public void start() {
        Log log = Log.get();
        TimerTask shutdownCheck = new TimerTask() {
            public void run() {
                Log.setLogForCurrentThread(log);
                Log.debug("Checking port file status...");
                try {
                    if (!portFile.exists()) {
                        // Time to quit because the portfile was deleted by another
                        // process, probably by the makefile that is done building.
                        server.shutdown("Quitting because portfile was deleted!");
                    } else if (portFile.markedForStop()) {
                        // Time to quit because another process touched the file
                        // server.port.stop to signal that the server should stop.
                        // This is necessary on some operating systems that lock
                        // the port file hard!
                        server.shutdown("Quitting because a portfile.stop file was found!");
                    } else if (!portFile.stillMyValues()) {
                        // Time to quit because another build has started.
                        server.shutdown("Quitting because portfile is now owned by another javac server!");
                    }
                } catch (IOException e) {
                    Log.error("IOException caught in PortFileMonitor.");
                    Log.debug(e);
                } catch (InterruptedException e) {
                    Thread.currentThread().interrupt();
                    Log.error(e);
                }
            }
        };

        timer.schedule(shutdownCheck, 0, CHECK_PORTFILE_INTERVAL);
    }

    public void shutdown() {
        timer.cancel();
    }
}