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 write-lock to Composite
*/
@AppliesTo( WriteLock.class )
public class WriteLockConcern
extends ConcernOf<InvocationHandler>
implements InvocationHandler
{
private
@This
ReadWriteLock lock;
@Override
public Object invoke( Object o, Method method, Object[] objects )
throws Throwable
{
Lock writeLock = lock.writeLock();
lock(writeLock);
try
{
return next.invoke( o, method, objects );
}
finally
{
try
{
writeLock.unlock();
}
catch( Exception e )
{
e.printStackTrace();
}
}
}
/**
* Fix for this bug:
* http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6822370
*/
protected void lock(Lock lock)
{
while(true)
{
try
{
while( !(lock.tryLock() || lock.tryLock( 1000, TimeUnit.MILLISECONDS )) )
{
// On timeout, try again
}
return; // Finally got a lock
}
catch( InterruptedException e )
{
// Try again
}
}
}
}