1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/classes/com/sun/tools/sjavac/server/PortFile.java Wed Apr 27 01:34:52 2016 +0800
1.3 @@ -0,0 +1,259 @@
1.4 +/*
1.5 + * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation. Oracle designates this
1.11 + * particular file as subject to the "Classpath" exception as provided
1.12 + * by Oracle in the LICENSE file that accompanied this code.
1.13 + *
1.14 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.15 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.16 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.17 + * version 2 for more details (a copy is included in the LICENSE file that
1.18 + * accompanied this code).
1.19 + *
1.20 + * You should have received a copy of the GNU General Public License version
1.21 + * 2 along with this work; if not, write to the Free Software Foundation,
1.22 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.23 + *
1.24 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.25 + * or visit www.oracle.com if you need additional information or have any
1.26 + * questions.
1.27 + */
1.28 +
1.29 +package com.sun.tools.sjavac.server;
1.30 +
1.31 +import java.io.File;
1.32 +import java.io.FileNotFoundException;
1.33 +import java.io.IOException;
1.34 +import java.io.RandomAccessFile;
1.35 +import java.nio.channels.ClosedChannelException;
1.36 +import java.nio.channels.FileChannel;
1.37 +import java.nio.channels.FileLock;
1.38 +import java.nio.channels.FileLockInterruptionException;
1.39 +import com.sun.tools.sjavac.Log;
1.40 +
1.41 +/**
1.42 + * The PortFile class mediates access to a short binary file containing the tcp/ip port (for the localhost)
1.43 + * and a cookie necessary for the server answering on that port. The file can be locked using file system
1.44 + * primitives to avoid race conditions when several javac clients are started at the same. Note that file
1.45 + * system locking is not always supported on a all operating systems and/or file systems.
1.46 + *
1.47 + * <p><b>This is NOT part of any supported API.
1.48 + * If you write code that depends on this, you do so at your own
1.49 + * risk. This code and its internal interfaces are subject to change
1.50 + * or deletion without notice.</b></p>
1.51 + */
1.52 +class PortFile {
1.53 +
1.54 + // Port file format:
1.55 + // byte ordering: high byte first = big endian
1.56 + // Magic nr, 4 byte int, first in file.
1.57 + private final static int magicNr = 0x1174;
1.58 + // Followed by a 4 byte int, with the port nr.
1.59 + // Followed by a 8 byte long, with cookie nr.
1.60 +
1.61 + private String filename;
1.62 + private File file;
1.63 + private File stopFile;
1.64 + private RandomAccessFile rwfile;
1.65 + private FileChannel channel;
1.66 + private FileLock lock;
1.67 +
1.68 + private boolean containsPortInfo;
1.69 + private int serverPort;
1.70 + private long serverCookie;
1.71 + private int myServerPort;
1.72 + private long myServerCookie;
1.73 +
1.74 + /**
1.75 + * Create a new portfile.
1.76 + * @param filename is the path to the file.
1.77 + */
1.78 + public PortFile(String fn) throws FileNotFoundException
1.79 + {
1.80 + filename = fn;
1.81 + file = new File(filename);
1.82 + stopFile = new File(filename+".stop");
1.83 + rwfile = new RandomAccessFile(file, "rw");
1.84 + // The rwfile should only be readable by the owner of the process
1.85 + // and no other! How do we do that on a RandomAccessFile?
1.86 + channel = rwfile.getChannel();
1.87 + containsPortInfo = false;
1.88 + lock = null;
1.89 + }
1.90 +
1.91 + /**
1.92 + * Lock the port file.
1.93 + */
1.94 + void lock() throws IOException {
1.95 + lock = channel.lock();
1.96 + }
1.97 +
1.98 + /**
1.99 + * Read the values from the port file in the file system.
1.100 + * Expects the port file to be locked.
1.101 + */
1.102 + public void getValues() {
1.103 + containsPortInfo = false;
1.104 + if (lock == null) {
1.105 + // Not locked, remain ignorant about port file contents.
1.106 + return;
1.107 + }
1.108 + try {
1.109 + if (rwfile.length()>0) {
1.110 + rwfile.seek(0);
1.111 + int nr = rwfile.readInt();
1.112 + serverPort = rwfile.readInt();
1.113 + serverCookie = rwfile.readLong();
1.114 +
1.115 + if (nr == magicNr) {
1.116 + containsPortInfo = true;
1.117 + } else {
1.118 + containsPortInfo = false;
1.119 + }
1.120 + }
1.121 + } catch (Exception e) {
1.122 + containsPortInfo = false;
1.123 + }
1.124 + }
1.125 +
1.126 + /**
1.127 + * Did the locking and getValues succeed?
1.128 + */
1.129 + public boolean containsPortInfo() {
1.130 + return containsPortInfo;
1.131 + }
1.132 +
1.133 + /**
1.134 + * If so, then we can acquire the tcp/ip port on localhost.
1.135 + */
1.136 + public int getPort() {
1.137 + assert(containsPortInfo);
1.138 + return serverPort;
1.139 + }
1.140 +
1.141 + /**
1.142 + * If so, then we can acquire the server cookie.
1.143 + */
1.144 + public long getCookie() {
1.145 + assert(containsPortInfo);
1.146 + return serverCookie;
1.147 + }
1.148 +
1.149 + /**
1.150 + * Store the values into the locked port file.
1.151 + */
1.152 + public void setValues(int port, long cookie) throws IOException {
1.153 + assert(lock != null);
1.154 + rwfile.seek(0);
1.155 + // Write the magic nr that identifes a port file.
1.156 + rwfile.writeInt(magicNr);
1.157 + rwfile.writeInt(port);
1.158 + rwfile.writeLong(cookie);
1.159 + myServerPort = port;
1.160 + myServerCookie = cookie;
1.161 + }
1.162 +
1.163 + /**
1.164 + * Delete the port file.
1.165 + */
1.166 + public void delete() throws IOException {
1.167 + // Access to file must be closed before deleting.
1.168 + rwfile.close();
1.169 + // Now delete.
1.170 + file.delete();
1.171 + }
1.172 +
1.173 + /**
1.174 + * Is the port file still there?
1.175 + */
1.176 + public boolean exists() throws IOException {
1.177 + return file.exists();
1.178 + }
1.179 +
1.180 + /**
1.181 + * Is a stop file there?
1.182 + */
1.183 + public boolean markedForStop() throws IOException {
1.184 + if (stopFile.exists()) {
1.185 + try {
1.186 + stopFile.delete();
1.187 + } catch (Exception e)
1.188 + {}
1.189 + return true;
1.190 + }
1.191 + return false;
1.192 + }
1.193 +
1.194 + /**
1.195 + * Unlock the port file.
1.196 + */
1.197 + public void unlock() throws IOException {
1.198 + assert(lock != null);
1.199 + lock.release();
1.200 + lock = null;
1.201 + }
1.202 +
1.203 + /**
1.204 + * Wait for the port file to contain values that look valid.
1.205 + * Return true, if a-ok, false if the valid values did not materialize within 5 seconds.
1.206 + */
1.207 + public synchronized boolean waitForValidValues() throws IOException, FileNotFoundException {
1.208 + for (int tries = 0; tries < 50; tries++) {
1.209 + lock();
1.210 + getValues();
1.211 + unlock();
1.212 + if (containsPortInfo) {
1.213 + Log.debug("Found valid values in port file after waiting "+(tries*100)+"ms");
1.214 + return true;
1.215 + }
1.216 + try {
1.217 + Thread.sleep(100);
1.218 + } catch (InterruptedException e)
1.219 + {}
1.220 + }
1.221 + Log.debug("Gave up waiting for valid values in port file");
1.222 + return false;
1.223 + }
1.224 +
1.225 + /**
1.226 + * Check if the portfile still contains my values, assuming that I am the server.
1.227 + */
1.228 + public synchronized boolean stillMyValues() throws IOException, FileNotFoundException {
1.229 + for (;;) {
1.230 + try {
1.231 + lock();
1.232 + getValues();
1.233 + unlock();
1.234 + if (containsPortInfo) {
1.235 + if (serverPort == myServerPort &&
1.236 + serverCookie == myServerCookie) {
1.237 + // Everything is ok.
1.238 + return true;
1.239 + }
1.240 + // Someone has overwritten the port file.
1.241 + // Probably another javac server, lets quit.
1.242 + return false;
1.243 + }
1.244 + // Something else is wrong with the portfile. Lets quit.
1.245 + return false;
1.246 + } catch (FileLockInterruptionException e) {
1.247 + continue;
1.248 + }
1.249 + catch (ClosedChannelException e) {
1.250 + // The channel has been closed since sjavac is exiting.
1.251 + return false;
1.252 + }
1.253 + }
1.254 + }
1.255 +
1.256 + /**
1.257 + * Return the name of the port file.
1.258 + */
1.259 + public String getFilename() {
1.260 + return filename;
1.261 + }
1.262 +}
