| /* |
| * Copyright 2007-2011 Rickard Oberg. |
| * Copyright 2007-2012 Niclas Hedhman. |
| * |
| * 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.qi4j.library.locking; |
| |
| import java.lang.reflect.InvocationHandler; |
| import java.lang.reflect.Method; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.locks.Lock; |
| import java.util.concurrent.locks.ReadWriteLock; |
| import org.qi4j.api.common.AppliesTo; |
| import org.qi4j.api.concern.ConcernOf; |
| import org.qi4j.api.injection.scope.This; |
| |
| /** |
| * Applies read-lock to Composite |
| */ |
| @AppliesTo( ReadLock.class ) |
| public class ReadLockConcern |
| extends ConcernOf<InvocationHandler> |
| implements InvocationHandler |
| { |
| private |
| @This |
| ReadWriteLock lock; |
| |
| @Override |
| public Object invoke( Object o, Method method, Object[] objects ) |
| throws Throwable |
| { |
| Lock readLock = lock.readLock(); |
| lock( readLock ); |
| try |
| { |
| return next.invoke( o, method, objects ); |
| } |
| finally |
| { |
| try |
| { |
| lock.readLock().unlock(); |
| } |
| catch( Exception e ) |
| { |
| e.printStackTrace(); |
| } |
| } |
| } |
| |
| /** |
| * Fix for this bug: |
| * http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6822370 |
| * |
| * @param lock the lock to be acquired. |
| */ |
| protected void lock( Lock lock ) |
| { |
| while(true) |
| { |
| try |
| { |
| //noinspection StatementWithEmptyBody |
| while( !lock.tryLock( 1000, TimeUnit.MILLISECONDS ) ) |
| { |
| // On timeout, try again |
| } |
| return; // Finally got a lock |
| } |
| catch( InterruptedException e ) |
| { |
| // Try again |
| } |
| } |
| } |
| } |