jdk8-mips64-public/langtools: src/share/classes/com/sun/tools/sjavac/server/PortFile.java@93012e2a5d1d (annotated)

src/share/classes/com/sun/tools/sjavac/server/PortFile.java@93012e2a5d1d (annotated)

src/share/classes/com/sun/tools/sjavac/server/PortFile.java

Sat, 07 Nov 2020 10:30:02 +0800

author: aoqi
date: Sat, 07 Nov 2020 10:30:02 +0800
changeset 3938: 93012e2a5d1d
parent 2525: 2eb010b6cb22
permissions: -rw-r--r--

Added tag mips-jdk8u275-b01 for changeset eb6ee6a5f2fe

 /*
  * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * 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).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */
 package com.sun.tools.sjavac.server;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.RandomAccessFile;
 import java.nio.channels.ClosedChannelException;
 import java.nio.channels.FileChannel;
 import java.nio.channels.FileLock;
 import java.nio.channels.FileLockInterruptionException;
 import com.sun.tools.sjavac.Log;
 /**
  * The PortFile class mediates access to a short binary file containing the tcp/ip port (for the localhost)
  * and a cookie necessary for the server answering on that port. The file can be locked using file system
  * primitives to avoid race conditions when several javac clients are started at the same. Note that file
  * system locking is not always supported on a all operating systems and/or file systems.
  *
  * <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></p>
  */
 class PortFile {
     // Port file format:
     // byte ordering: high byte first = big endian
     // Magic nr, 4 byte int, first in file.
     private final static int magicNr = 0x1174;
     // Followed by a 4 byte int, with the port nr.
     // Followed by a 8 byte long, with cookie nr.
     private String filename;
     private File file;
     private File stopFile;
     private RandomAccessFile rwfile;
     private FileChannel channel;
     private FileLock lock;
     private boolean containsPortInfo;
     private int serverPort;
     private long serverCookie;
     private int myServerPort;
     private long myServerCookie;
     /**
      * Create a new portfile.
      * @param filename is the path to the file.
      */
     public PortFile(String fn) throws FileNotFoundException
     {
         filename = fn;
         file = new File(filename);
         stopFile = new File(filename+".stop");
         rwfile = new RandomAccessFile(file, "rw");
         // The rwfile should only be readable by the owner of the process
         // and no other! How do we do that on a RandomAccessFile?
         channel = rwfile.getChannel();
         containsPortInfo = false;
         lock = null;
     }
     /**
      * Lock the port file.
      */
     void lock() throws IOException {
         lock = channel.lock();
     }
     /**
      * Read the values from the port file in the file system.
      * Expects the port file to be locked.
      */
     public void getValues()  {
         containsPortInfo = false;
         if (lock == null) {
             // Not locked, remain ignorant about port file contents.
             return;
         }
         try {
             if (rwfile.length()>0) {
                 rwfile.seek(0);
                 int nr = rwfile.readInt();
                 serverPort = rwfile.readInt();
                 serverCookie = rwfile.readLong();
                 if (nr == magicNr) {
                     containsPortInfo = true;
                 } else {
                     containsPortInfo = false;
                 }
             }
         } catch (Exception e) {
             containsPortInfo = false;
         }
     }
     /**
      * Did the locking and getValues succeed?
      */
     public boolean containsPortInfo() {
         return containsPortInfo;
     }
     /**
      * If so, then we can acquire the tcp/ip port on localhost.
      */
     public int getPort() {
         assert(containsPortInfo);
         return serverPort;
     }
     /**
      * If so, then we can acquire the server cookie.
      */
     public long getCookie() {
         assert(containsPortInfo);
         return serverCookie;
     }
     /**
      * Store the values into the locked port file.
      */
     public void setValues(int port, long cookie) throws IOException {
         assert(lock != null);
         rwfile.seek(0);
         // Write the magic nr that identifes a port file.
         rwfile.writeInt(magicNr);
         rwfile.writeInt(port);
         rwfile.writeLong(cookie);
         myServerPort = port;
         myServerCookie = cookie;
     }
     /**
      * Delete the port file.
      */
     public void delete() throws IOException {
         // Access to file must be closed before deleting.
         rwfile.close();
         // Now delete.
         file.delete();
     }
     /**
      * Is the port file still there?
      */
     public boolean exists() throws IOException {
         return file.exists();
     }
     /**
      * Is a stop file there?
      */
     public boolean markedForStop() throws IOException {
         if (stopFile.exists()) {
             try {
                 stopFile.delete();
             } catch (Exception e)
             {}
             return true;
         }
         return false;
     }
     /**
      * Unlock the port file.
      */
     public void unlock() throws IOException {
         assert(lock != null);
         lock.release();
         lock = null;
     }
     /**
      * Wait for the port file to contain values that look valid.
      * Return true, if a-ok, false if the valid values did not materialize within 5 seconds.
      */
     public synchronized boolean waitForValidValues() throws IOException, FileNotFoundException {
         for (int tries = 0; tries < 50; tries++) {
             lock();
             getValues();
             unlock();
             if (containsPortInfo) {
                 Log.debug("Found valid values in port file after waiting "+(tries*100)+"ms");
                 return true;
             }
             try {
                 Thread.sleep(100);
             } catch (InterruptedException e)
             {}
         }
         Log.debug("Gave up waiting for valid values in port file");
         return false;
     }
     /**
      * Check if the portfile still contains my values, assuming that I am the server.
      */
     public synchronized boolean stillMyValues() throws IOException, FileNotFoundException {
         for (;;) {
             try {
                 lock();
                 getValues();
                 unlock();
                 if (containsPortInfo) {
                     if (serverPort == myServerPort &&
                         serverCookie == myServerCookie) {
                         // Everything is ok.
                         return true;
                     }
                     // Someone has overwritten the port file.
                     // Probably another javac server, lets quit.
                     return false;
                 }
                 // Something else is wrong with the portfile. Lets quit.
                 return false;
             } catch (FileLockInterruptionException e) {
                 continue;
             }
             catch (ClosedChannelException e) {
                 // The channel has been closed since sjavac is exiting.
                 return false;
             }
         }
     }
     /**
      * Return the name of the port file.
      */
     public String getFilename() {
         return filename;
     }
 }

Mercurial > jdk8-mips64-public > langtools / annotate

src/share/classes/com/sun/tools/sjavac/server/PortFile.java@93012e2a5d1d (annotated)

src/share/classes/com/sun/tools/sjavac/server/PortFile.java