1 /* 2 * Copyright (c) 2013, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package javafx.scene.web; 27 28 import com.sun.javafx.logging.PlatformLogger; 29 import java.io.File; 30 import java.io.IOException; 31 import java.io.RandomAccessFile; 32 import static java.lang.String.format; 33 import java.nio.channels.FileLock; 34 import java.nio.channels.OverlappingFileLockException; 35 import java.util.HashMap; 36 import java.util.Map; 37 38 final class DirectoryLock { 39 40 private static final PlatformLogger logger = 41 PlatformLogger.getLogger(DirectoryLock.class.getName()); 42 private static final Map<File,Descriptor> descriptors = new HashMap<>(); 43 44 45 private Descriptor descriptor; 46 47 48 DirectoryLock(File directory) throws IOException, 49 DirectoryAlreadyInUseException 50 { 51 directory = canonicalize(directory); 52 descriptor = descriptors.get(directory); 53 if (descriptor == null) { 54 File lockFile = lockFile(directory); 55 RandomAccessFile lockRaf = new RandomAccessFile(lockFile, "rw"); 56 try { 57 FileLock lock = lockRaf.getChannel().tryLock(); 58 if (lock == null) { 59 throw new DirectoryAlreadyInUseException( 60 directory.toString(), null); 61 } 62 descriptor = new Descriptor(directory, lockRaf, lock); 63 descriptors.put(directory, descriptor); 64 } catch (OverlappingFileLockException ex) { 65 throw new DirectoryAlreadyInUseException( 66 directory.toString(), ex); 67 } finally { 68 if (descriptor == null) { // tryLock failed 69 try { 70 lockRaf.close(); 71 } catch (IOException ex) { 72 logger.warning(format("Error closing [%s]", 73 lockFile), ex); 74 } 75 } 76 } 77 } 78 descriptor.referenceCount++; 79 } 80 81 82 void close() { 83 if (descriptor == null) { 84 return; 85 } 86 descriptor.referenceCount--; 87 if (descriptor.referenceCount == 0) { 88 try { 89 descriptor.lock.release(); 90 } catch (IOException ex) { 91 logger.warning(format("Error releasing lock on [%s]", 92 lockFile(descriptor.directory)), ex); 93 } 94 try { 95 descriptor.lockRaf.close(); 96 } catch (IOException ex) { 97 logger.warning(format("Error closing [%s]", 98 lockFile(descriptor.directory)), ex); 99 } 100 descriptors.remove(descriptor.directory); 101 } 102 descriptor = null; 103 } 104 105 106 static int referenceCount(File directory) throws IOException { 107 Descriptor d = descriptors.get(canonicalize(directory)); 108 return d == null ? 0 : d.referenceCount; 109 } 110 111 static File canonicalize(File directory) throws IOException { 112 String path = directory.getCanonicalPath(); 113 if (path.length() > 0 114 && path.charAt(path.length() - 1) != File.separatorChar) 115 { 116 path += File.separatorChar; 117 } 118 return new File(path); 119 } 120 121 private static File lockFile(File directory) { 122 return new File(directory, ".lock"); 123 } 124 125 126 private static class Descriptor { 127 private final File directory; 128 private final RandomAccessFile lockRaf; 129 private final FileLock lock; 130 private int referenceCount; 131 132 private Descriptor(File directory, 133 RandomAccessFile lockRaf, 134 FileLock lock) 135 { 136 this.directory = directory; 137 this.lockRaf = lockRaf; 138 this.lock = lock; 139 } 140 } 141 142 final class DirectoryAlreadyInUseException extends Exception { 143 DirectoryAlreadyInUseException(String message, Throwable cause) { 144 super(message, cause); 145 } 146 } 147 }