org.eclipse.sisu.inject.DefaultBeanLocator Maven / Gradle / Ivy
/*******************************************************************************
* Copyright (c) 2010-present Sonatype, Inc.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Stuart McCulloch (Sonatype, Inc.) - initial API and implementation
*******************************************************************************/
package org.eclipse.sisu.inject;
import java.util.Map;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import javax.inject.Inject;
import org.eclipse.sisu.BeanEntry;
import org.eclipse.sisu.Mediator;
import com.google.inject.Binding;
import com.google.inject.Injector;
import com.google.inject.Key;
import com.google.inject.Singleton;
import com.google.inject.TypeLiteral;
/**
* Default {@link MutableBeanLocator} that locates qualified beans across a dynamic group of {@link BindingPublisher}s.
*/
@Singleton
@SuppressWarnings( { "rawtypes", "unchecked" } )
public final class DefaultBeanLocator
implements MutableBeanLocator
{
// ----------------------------------------------------------------------
// Implementation fields
// ----------------------------------------------------------------------
private final RankedSequence publishers = new RankedSequence();
private final ConcurrentMap cachedBindings = Weak.concurrentValues( 256, 1 );
// reverse mapping; can't use watcher as key since it may not be unique
private final Map cachedWatchers = Weak.values();
private final ImplicitBindings implicitBindings = new ImplicitBindings( publishers );
private final Long[] typeIdHolder = new Long[1];
private final ReentrantReadWriteLock publisherLock = new ReentrantReadWriteLock();
// ----------------------------------------------------------------------
// Public methods
// ----------------------------------------------------------------------
public Iterable locate( final Key key )
{
final TypeLiteral type = key.getTypeLiteral();
RankedBindings bindings = fetchBindings( type, null );
if ( null == bindings )
{
synchronized ( cachedBindings ) // perform new lookup
{
bindings = fetchBindings( type, typeIdHolder );
if ( null == bindings )
{
// still not cached, so go ahead with assigned id
bindings = new RankedBindings( type, publishers );
cachedBindings.put( typeIdHolder[0], bindings );
}
}
}
final boolean isImplicit = key.getAnnotationType() == null && TypeArguments.isImplicit( type );
return new LocatedBeans( key, bindings, isImplicit ? implicitBindings : null );
}
public void watch( final Key key, final Mediator mediator, final Object watcher )
{
publisherLock.readLock().lock();
try
{
// subscribe new watcher to existing publishers while holding the read-lock
final WatchedBeans beans = new WatchedBeans( key, mediator, watcher );
for ( final BindingPublisher p : publishers() )
{
p.subscribe( beans );
}
synchronized ( cachedWatchers )
{
cachedWatchers.put( beans, watcher );
}
}
finally
{
publisherLock.readLock().unlock();
}
}
public boolean add( final BindingPublisher publisher )
{
final WatchedBeans[] currentWatchers;
publisherLock.writeLock().lock();
try
{
if ( publishers.contains( publisher ) )
{
return false;
}
Logs.trace( "Add publisher: {}", publisher, null );
synchronized ( cachedBindings ) // block new lookup while we update the cache
{
final int rank = publisher.maxBindingRank();
publishers.insert( publisher, rank );
for ( final RankedBindings bindings : cachedBindings.values() )
{
bindings.add( publisher, rank );
}
}
synchronized ( cachedWatchers )
{
// capture snapshot of current watchers while we hold the write-lock
currentWatchers = cachedWatchers.keySet().toArray( new WatchedBeans[0] );
}
publisherLock.readLock().lock(); // begin downgrade to the read-lock
}
finally
{
publisherLock.writeLock().unlock();
}
try
{
// subscribe watchers to the new publisher while holding the read-lock
for ( final WatchedBeans beans : currentWatchers )
{
publisher.subscribe( beans );
}
}
finally
{
publisherLock.readLock().unlock();
}
return true;
}
public boolean remove( final BindingPublisher publisher )
{
final BindingPublisher oldPublisher;
final WatchedBeans[] currentWatchers;
publisherLock.writeLock().lock();
try
{
synchronized ( cachedBindings ) // block new lookup while we update the cache
{
oldPublisher = publishers.remove( publisher );
if ( null == oldPublisher )
{
return false;
}
Logs.trace( "Remove publisher: {}", oldPublisher, null );
for ( final RankedBindings bindings : cachedBindings.values() )
{
bindings.remove( oldPublisher );
}
}
synchronized ( cachedWatchers )
{
// capture snapshot of current watchers while we hold the write-lock
currentWatchers = cachedWatchers.keySet().toArray( new WatchedBeans[0] );
}
publisherLock.readLock().lock(); // begin downgrade to the read-lock
}
finally
{
publisherLock.writeLock().unlock();
}
try
{
// unsubscribe watchers from the old publisher while holding the read-lock
for ( final WatchedBeans beans : currentWatchers )
{
oldPublisher.unsubscribe( beans );
}
}
finally
{
publisherLock.readLock().unlock();
}
// one last round of cleanup in case more was freed
( (MildConcurrentValues) cachedBindings ).compact();
return true;
}
public Iterable publishers()
{
return publishers.snapshot();
}
public void clear()
{
for ( final BindingPublisher p : publishers() )
{
remove( p );
}
}
// ----------------------------------------------------------------------
// Implementation methods
// ----------------------------------------------------------------------
/**
* Fetches any bindings currently associated with the given type.
*
* @param type The generic type
* @param idReturn Optional holder, returns the assigned type id
* @return Associated bindings; {@code null} if this is a new type
*/
@SuppressWarnings( "boxing" )
private RankedBindings fetchBindings( final TypeLiteral type, final Long[] idReturn )
{
// type hash with loader hash is nominally unique, but handle collisions just in case
final int loaderHash = System.identityHashCode( type.getRawType().getClassLoader() );
long id = (long) type.hashCode() << 32 | 0x00000000FFFFFFFFL & loaderHash;
RankedBindings result;
while ( null != ( result = cachedBindings.get( id ) ) && !type.equals( result.type() ) )
{
id++; // collision! (should be very rare) ... resort to linear scan from base id
}
if ( null != idReturn )
{
idReturn[0] = id;
}
return result;
}
/**
* Automatically publishes any {@link Injector} that contains a binding to this {@link BeanLocator}.
*
* Relies on Guice's auto-injection, bind the locator with a Provider to disable this feature.
*
* @param injector The injector
*/
@Inject
void autoPublish( final Injector injector )
{
add( InjectorBindings.findBindingPublisher( injector ) );
}
/**
* Automatically publishes child {@link Injector}s that inherit a binding to this {@link BeanLocator}.
*
* Assumes module(s) used to create the child injector request static injection of this class.
*
* @param childInjector The child injector
*/
@Inject
static void autoPublishChild( final Injector childInjector )
{
// Child injectors cannot use the first 'autoPublish' trick because the locator binding is typically inherited
// from their parent and the locator instance has already been auto-injected. We workaround this limitation by
// requesting static injection of this class in a child module, such as ChildWireModule.
// When the child injector calls us we introspect the locator binding to see if 'autoPublish' would have been
// called in the parent. We avoid checking the provided instance directly since it may have been deliberately
// hidden behind a Provider to disable the 'autoPublish' feature, and we need to respect that. Instead we use
// the Implementations utility to test whether the binding directly exposes this implementation class.
final Binding locatorBinding = childInjector.getBinding( MutableBeanLocator.class );
if ( DefaultBeanLocator.class.equals( Implementations.find( locatorBinding ) ) )
{
( (DefaultBeanLocator) locatorBinding.getProvider().get() ).autoPublish( childInjector );
}
}
}