/*
* Copyright 2003-2015 JetBrains s.r.o.
*
* 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 jetbrains.mps.extapi.module;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.mps.openapi.module.SModule;
import org.jetbrains.mps.openapi.module.SModuleReference;
import org.jetbrains.mps.openapi.module.SRepository;
import org.jetbrains.mps.openapi.module.SRepositoryAttachListener;
import org.jetbrains.mps.openapi.module.SRepositoryListener;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicInteger;
/**
* This class dispatches repository events to SRepositoryListener clients
*/
public class SRepositoryEventsDispatcher {
private final List<SRepositoryListener> myListeners = new CopyOnWriteArrayList<SRepositoryListener>();
// AtomicInteger is not to guard against registration from parallel threads, rather a convenient way to have modifiable Integer
private final ConcurrentHashMap<SRepositoryListener, AtomicInteger> myListenerCount = new ConcurrentHashMap<SRepositoryListener, AtomicInteger>();
private final SRepository myRepository;
public SRepositoryEventsDispatcher(@NotNull SRepository repository) {
myRepository = repository;
}
public final void addRepositoryListener(SRepositoryListener listener) {
myListenerCount.putIfAbsent(listener, new AtomicInteger(0));
if (myListenerCount.get(listener).incrementAndGet() != 1) {
// It's not the first time this listener is attached to the repository
return;
}
myListeners.add(listener);
if (listener instanceof SRepositoryAttachListener) {
myRepository.getModelAccess().checkReadAccess();
((SRepositoryAttachListener) listener).startListening(myRepository);
}
}
public final void removeRepositoryListener(SRepositoryListener listener) {
AtomicInteger lc = myListenerCount.get(listener);
if (lc == null || lc.decrementAndGet() != 0) {
// either already removed, or registered more than once, wait until the last one is removed
return;
}
myListenerCount.remove(listener);
if (listener instanceof SRepositoryAttachListener) {
myRepository.getModelAccess().checkReadAccess();
((SRepositoryAttachListener) listener).stopListening(myRepository);
}
myListeners.remove(listener);
}
public final void fireModuleAdded(@NotNull SModule module) {
myRepository.getModelAccess().checkWriteAccess();
for (SRepositoryListener listener : myListeners) {
listener.moduleAdded(module);
}
}
// TODO : there is a need to introduce some kind of priority for SRepositoryListener.
// For example, class loading system wants to be the first to know everything about modules' addition/removal (important to handle an event before a potential client)
// As for now, just notifying
public final void fireBeforeModuleRemoved(@NotNull SModule module) {
myRepository.getModelAccess().checkWriteAccess();
for (SRepositoryListener listener : myListeners) {
listener.beforeModuleRemoved(module);
}
}
public final void fireModuleRemoved(@NotNull SModuleReference module) {
myRepository.getModelAccess().checkWriteAccess();
for (SRepositoryListener listener : myListeners) {
listener.moduleRemoved(module);
}
}
public final void fireCommandStarted() {
myRepository.getModelAccess().checkWriteAccess();
for (SRepositoryListener listener : myListeners) {
listener.commandStarted(myRepository);
}
}
public final void fireCommandFinished() {
myRepository.getModelAccess().checkWriteAccess();
for (SRepositoryListener listener : myListeners) {
listener.commandFinished(myRepository);
}
}
}