| /* 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.harmony.nio.internal; |
| |
| import java.nio.channels.FileLock; |
| import java.nio.channels.OverlappingFileLockException; |
| import java.util.Comparator; |
| import java.util.Iterator; |
| import java.util.SortedSet; |
| import java.util.TreeSet; |
| |
| /** |
| * The lock manager is responsible for tracking acquired and pending locks on |
| * the underlying file channel. |
| * |
| */ |
| final class LockManager { |
| // The set of acquired and pending locks. |
| private final Comparator<FileLock> lockComparator = new Comparator<FileLock>() { |
| public int compare(FileLock lock1, FileLock lock2) { |
| long position1 = lock1.position(); |
| long position2 = lock2.position(); |
| return position1 > position2 ? 1 : (position1 < position2 ? -1 : 0); |
| } |
| }; |
| |
| private final SortedSet<FileLock> locks = new TreeSet<FileLock>( |
| lockComparator); |
| |
| /* |
| * Default Constructor. |
| */ |
| protected LockManager() { |
| super(); |
| } |
| |
| /* |
| * Add a new pending lock to the manager. Throws an exception if the lock |
| * would overlap an existing lock. Once the lock is acquired it remains in |
| * this set as an acquired lock. |
| */ |
| synchronized void addLock(FileLock lock) |
| throws OverlappingFileLockException { |
| long lockEnd = lock.position() + lock.size(); |
| for (Iterator<FileLock> keyItr = locks.iterator(); keyItr.hasNext();) { |
| FileLock existingLock = keyItr.next(); |
| if (existingLock.position() > lockEnd) { |
| // This, and all remaining locks, start beyond our end (so |
| // cannot overlap). |
| break; |
| } |
| if (existingLock.overlaps(lock.position(), lock.size())) { |
| throw new OverlappingFileLockException(); |
| } |
| } |
| locks.add(lock); |
| } |
| |
| /* |
| * Removes an acquired lock from the lock manager. If the lock did not exist |
| * in the lock manager the operation is a no-op. |
| */ |
| synchronized void removeLock(FileLock lock) { |
| locks.remove(lock); |
| } |
| } |