| package org.eclipse.aether.internal.impl; |
| |
| /* |
| * 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. |
| */ |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.io.ByteArrayInputStream; |
| import java.io.ByteArrayOutputStream; |
| import java.io.Closeable; |
| import java.io.File; |
| import java.io.FileInputStream; |
| import java.io.IOException; |
| import java.io.RandomAccessFile; |
| import java.nio.channels.FileChannel; |
| import java.nio.channels.FileLock; |
| import java.nio.channels.OverlappingFileLockException; |
| import java.util.Map; |
| import java.util.Properties; |
| |
| /** |
| * Manages potentially concurrent accesses to a properties file. |
| */ |
| class TrackingFileManager |
| { |
| |
| private static final Logger LOGGER = LoggerFactory.getLogger( TrackingFileManager.class ); |
| |
| public Properties read( File file ) |
| { |
| synchronized ( getLock( file ) ) |
| { |
| FileLock lock = null; |
| FileInputStream stream = null; |
| try |
| { |
| if ( !file.exists() ) |
| { |
| return null; |
| } |
| |
| stream = new FileInputStream( file ); |
| |
| lock = lock( stream.getChannel(), Math.max( 1, file.length() ), true ); |
| |
| Properties props = new Properties(); |
| props.load( stream ); |
| |
| return props; |
| } |
| catch ( IOException e ) |
| { |
| LOGGER.warn( "Failed to read tracking file {}", file, e ); |
| } |
| finally |
| { |
| release( lock, file ); |
| close( stream, file ); |
| } |
| } |
| |
| return null; |
| } |
| |
| public Properties update( File file, Map<String, String> updates ) |
| { |
| Properties props = new Properties(); |
| |
| synchronized ( getLock( file ) ) |
| { |
| File directory = file.getParentFile(); |
| if ( !directory.mkdirs() && !directory.exists() ) |
| { |
| LOGGER.warn( "Failed to create parent directories for tracking file {}", file ); |
| return props; |
| } |
| |
| RandomAccessFile raf = null; |
| FileLock lock = null; |
| try |
| { |
| raf = new RandomAccessFile( file, "rw" ); |
| lock = lock( raf.getChannel(), Math.max( 1, raf.length() ), false ); |
| |
| if ( file.canRead() ) |
| { |
| byte[] buffer = new byte[(int) raf.length()]; |
| |
| raf.readFully( buffer ); |
| |
| ByteArrayInputStream stream = new ByteArrayInputStream( buffer ); |
| |
| props.load( stream ); |
| } |
| |
| for ( Map.Entry<String, String> update : updates.entrySet() ) |
| { |
| if ( update.getValue() == null ) |
| { |
| props.remove( update.getKey() ); |
| } |
| else |
| { |
| props.setProperty( update.getKey(), update.getValue() ); |
| } |
| } |
| |
| ByteArrayOutputStream stream = new ByteArrayOutputStream( 1024 * 2 ); |
| |
| LOGGER.debug( "Writing tracking file {}", file ); |
| props.store( stream, "NOTE: This is a Maven Resolver internal implementation file" |
| + ", its format can be changed without prior notice." ); |
| |
| raf.seek( 0 ); |
| raf.write( stream.toByteArray() ); |
| raf.setLength( raf.getFilePointer() ); |
| } |
| catch ( IOException e ) |
| { |
| LOGGER.warn( "Failed to write tracking file {}", file, e ); |
| } |
| finally |
| { |
| release( lock, file ); |
| close( raf, file ); |
| } |
| } |
| |
| return props; |
| } |
| |
| private void release( FileLock lock, File file ) |
| { |
| if ( lock != null ) |
| { |
| try |
| { |
| lock.release(); |
| } |
| catch ( IOException e ) |
| { |
| LOGGER.warn( "Error releasing lock for tracking file {}", file, e ); |
| } |
| } |
| } |
| |
| private void close( Closeable closeable, File file ) |
| { |
| if ( closeable != null ) |
| { |
| try |
| { |
| closeable.close(); |
| } |
| catch ( IOException e ) |
| { |
| LOGGER.warn( "Error closing tracking file {}", file, e ); |
| } |
| } |
| } |
| |
| private Object getLock( File file ) |
| { |
| /* |
| * NOTE: Locks held by one JVM must not overlap and using the canonical path is our best bet, still another |
| * piece of code might have locked the same file (unlikely though) or the canonical path fails to capture file |
| * identity sufficiently as is the case with Java 1.6 and symlinks on Windows. |
| */ |
| try |
| { |
| return file.getCanonicalPath().intern(); |
| } |
| catch ( IOException e ) |
| { |
| LOGGER.warn( "Failed to canonicalize path {}: {}", file, e.getMessage() ); |
| return file.getAbsolutePath().intern(); |
| } |
| } |
| |
| @SuppressWarnings( { "checkstyle:magicnumber" } ) |
| private FileLock lock( FileChannel channel, long size, boolean shared ) |
| throws IOException |
| { |
| FileLock lock = null; |
| |
| for ( int attempts = 8; attempts >= 0; attempts-- ) |
| { |
| try |
| { |
| lock = channel.lock( 0, size, shared ); |
| break; |
| } |
| catch ( OverlappingFileLockException e ) |
| { |
| if ( attempts <= 0 ) |
| { |
| throw new IOException( e ); |
| } |
| try |
| { |
| Thread.sleep( 50L ); |
| } |
| catch ( InterruptedException e1 ) |
| { |
| Thread.currentThread().interrupt(); |
| } |
| } |
| } |
| |
| if ( lock == null ) |
| { |
| throw new IOException( "Could not lock file" ); |
| } |
| |
| return lock; |
| } |
| |
| } |