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Diffstat (limited to 'simple/simple-common/src/main/java/org/simpleframework/common/buffer/FileWatcher.java')
| -rw-r--r-- | simple/simple-common/src/main/java/org/simpleframework/common/buffer/FileWatcher.java | 179 |
1 files changed, 179 insertions, 0 deletions
diff --git a/simple/simple-common/src/main/java/org/simpleframework/common/buffer/FileWatcher.java b/simple/simple-common/src/main/java/org/simpleframework/common/buffer/FileWatcher.java new file mode 100644 index 0000000..6d1f3b2 --- /dev/null +++ b/simple/simple-common/src/main/java/org/simpleframework/common/buffer/FileWatcher.java @@ -0,0 +1,179 @@ +/* + * FileWatcher.java February 2008 + * + * Copyright (C) 2008, Niall Gallagher <niallg@users.sf.net> + * + * Licensed 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.simpleframework.common.buffer; + +import java.io.File; +import java.io.FileFilter; +import java.io.IOException; + +/** + * The <code>FileWatcher</code> object is used to create files that + * are to be used for file buffers. All files created by this are + * created in the <code>java.io.tmpdir</code> path. Temporary files + * created in this directory last for a configurable length of time + * before they are deleted. + * + * @author Niall Gallagher + */ +class FileWatcher implements FileFilter { + + /** + * This is the prefix for the temporary files created. + */ + private final String prefix; + + /** + * This is the duration the files created will exist for. + */ + private final long duration; + + /** + * Constructor for the <code>FileWatcher</code> object. This will + * allow temporary files to exist for five minutes. After this + * time the will be removed from the underlying directory. Any + * request for a new file will result in a sweep of the temporary + * directory for all matching files, if they have expired they + * will be deleted. + * + * @param prefix this is the file name prefix for the files + */ + public FileWatcher(String prefix) { + this(prefix, 300000); + } + + /** + * Constructor for the <code>FileWatcher</code> object. This will + * allow temporary files to exist for a configurable length of time. + * After this time the will be removed from the underlying directory. + * Any request for a new file will result in a sweep of the temporary + * directory for all matching files, if they have expired they + * will be deleted. + * + * @param prefix this is the file name prefix for the files + * @param duration this is the duration the files exist for + */ + public FileWatcher(String prefix, long duration) { + this.duration = duration; + this.prefix = prefix; + } + + /** + * This will create a temporary file which can be used as a buffer + * for <code>FileBuffer</code> objects. The file returned by this + * method will be created before it is returned, which ensures it + * can be used as a means to buffer bytes. All files are created + * in the <code>java.io.tmpdir</code> location, which represents + * the underlying file system temporary file destination. + * + * @return this returns a created temporary file for buffers + */ + public File create() throws IOException { + File path = create(prefix); + + if(!path.isDirectory()) { + File parent = path.getParentFile(); + + if(parent.isDirectory()) { + clean(parent); + } + } + return path; + } + + /** + * This will create a temporary file which can be used as a buffer + * for <code>FileBuffer</code> objects. The file returned by this + * method will be created before it is returned, which ensures it + * can be used as a means to buffer bytes. All files are created + * in the <code>java.io.tmpdir</code> location, which represents + * the underlying file system temporary file destination. + * + * @param prefix this is the prefix of the file to be created + * + * @return this returns a created temporary file for buffers + */ + private File create(String prefix) throws IOException { + File file = File.createTempFile(prefix, null); + + if(!file.exists()) { + file.createNewFile(); + } + return file; + } + + /** + * When this method is invoked the files that match the pattern + * of the temporary files are evaluated for deletion. Only those + * files that have not been modified in the duration period can + * be deleted. This ensures the file system is not exhausted. + * + * @param path this is the path of the file to be evaluated + */ + private void clean(File path) throws IOException { + File[] list = path.listFiles(this); + + for(File next : list) { + for(int i = 0; i < 3; i++) { + if(next.delete()) { + break; + } + } + } + } + + /** + * This determines if the file provided is an acceptable file for + * deletion. Acceptable files are those that match the pattern + * of files created by this file system object. If the file is + * a matching file then it is a candidate for deletion. + * + * @param file this is the file to evaluate for deletion + * + * @return this returns true if the file matches the pattern + */ + public boolean accept(File file) { + String name = file.getName(); + + if(file.isDirectory()) { + return false; + } + return accept(file, name); + } + + /** + * This determines if the file provided is an acceptable file for + * deletion. Acceptable files are those that match the pattern + * of files created by this file system object. If the file is + * a matching file then it is a candidate for deletion. + * + * @param file this is the file to evaluate for deletion + * @param name this is the name of the file to be evaluated + * + * @return this returns true if the file matches the pattern + */ + private boolean accept(File file, String name) { + long time = System.currentTimeMillis(); + long modified = file.lastModified(); + + if(modified + duration > time) { // not yet expired + return false; + } + return name.startsWith(prefix); + } +} |