| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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.apache.ratis.util; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.io.IOException; |
| import java.io.File; |
| import java.io.FileNotFoundException; |
| import java.io.FileOutputStream; |
| import java.io.FilterOutputStream; |
| import java.util.concurrent.atomic.AtomicBoolean; |
| |
| /** |
| * A {@link FilterOutputStream} that writes to a file atomically. |
| * The output file will not show up until it has been entirely written and sync'ed to disk. |
| * It uses a temporary file when it is being written. |
| * The default temporary file has a .tmp suffix. |
| * |
| * When the output stream is closed, it is |
| * (1) flushed |
| * (2) sync'ed, and |
| * (3) renamed/moved from the temporary file to the output file. |
| * If the output file already exists, it will be overwritten. |
| * |
| * NOTE that on Windows platforms, the output file, if it exists, is deleted |
| * before the temporary file is moved. |
| */ |
| public class AtomicFileOutputStream extends FilterOutputStream { |
| static final Logger LOG = LoggerFactory.getLogger(AtomicFileOutputStream.class); |
| |
| public static final String TMP_EXTENSION = ".tmp"; |
| |
| public static File getTemporaryFile(File outFile) { |
| return new File(outFile.getParentFile(), outFile.getName() + TMP_EXTENSION); |
| } |
| |
| private final File outFile; |
| private final File tmpFile; |
| private final AtomicBoolean isClosed = new AtomicBoolean(); |
| |
| public AtomicFileOutputStream(File outFile) throws FileNotFoundException { |
| this(outFile, getTemporaryFile(outFile)); |
| } |
| |
| public AtomicFileOutputStream(File outFile, File tmpFile) throws FileNotFoundException { |
| super(new FileOutputStream(tmpFile)); |
| this.outFile = outFile.getAbsoluteFile(); |
| this.tmpFile = tmpFile.getAbsoluteFile(); |
| } |
| |
| public boolean isClosed() { |
| return isClosed.get(); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| if (!isClosed.compareAndSet(false, true)) { |
| return; |
| } |
| boolean forced = false; |
| boolean closed = false; |
| try { |
| flush(); |
| ((FileOutputStream)out).getChannel().force(true); |
| forced = true; |
| |
| super.close(); |
| closed = true; |
| |
| final boolean renamed = tmpFile.renameTo(outFile); |
| if (!renamed) { |
| // On windows, renameTo does not replace. |
| if (outFile.exists() && !outFile.delete()) { |
| throw new IOException("Could not delete original file " + outFile); |
| } |
| FileUtils.move(tmpFile, outFile); |
| } |
| } finally { |
| if (!closed) { |
| if (!forced) { |
| // If we failed when flushing, try to close it to not leak an FD |
| IOUtils.cleanup(LOG, out); |
| } |
| // close wasn't successful, try to delete the tmp file |
| if (!tmpFile.delete()) { |
| LOG.warn("Unable to delete tmp file " + tmpFile); |
| } |
| } |
| } |
| } |
| |
| /** |
| * Close the atomic file, but do not "commit" the temporary file |
| * on top of the destination. This should be used if there is a failure |
| * in writing. |
| */ |
| public void abort() { |
| if (isClosed.get()) { |
| return; |
| } |
| try { |
| super.close(); |
| } catch (IOException ioe) { |
| LOG.warn("Unable to abort file " + tmpFile, ioe); |
| } finally { |
| if (!tmpFile.delete()) { |
| LOG.warn("Unable to delete tmp file during abort " + tmpFile); |
| } |
| } |
| } |
| } |