jsedding commented on code in PR #100: URL: https://github.com/apache/sling-org-apache-sling-resourceresolver/pull/100#discussion_r1324428679
########## src/main/java/org/apache/sling/resourceresolver/impl/FactoryRegistrationHandler.java: ########## @@ -0,0 +1,178 @@ +/* + * 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.sling.resourceresolver.impl; + +import org.apache.sling.api.resource.ResourceResolverFactory; +import org.apache.sling.api.resource.runtime.RuntimeService; +import org.osgi.framework.Bundle; +import org.osgi.framework.BundleContext; +import org.osgi.framework.Constants; +import org.osgi.framework.ServiceFactory; +import org.osgi.framework.ServiceRegistration; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +import java.util.Dictionary; +import java.util.Hashtable; +import java.util.List; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.TimeUnit; + +public class FactoryRegistrationHandler implements AutoCloseable { + + private static final Logger LOG = LoggerFactory.getLogger(FactoryRegistrationHandler.class); + + private final ResourceResolverFactoryActivator activator; + + private final FactoryPreconditions factoryPreconditions; + + private final ExecutorService factoryRegistrationWorker; + + @SuppressWarnings("java:S3077") // The field is only ever set to null or to a new FactoryRegistration instance, which is safe. + private volatile FactoryRegistration factoryRegistration; + + public FactoryRegistrationHandler( + ResourceResolverFactoryActivator activator, FactoryPreconditions factoryPreconditions) { + this.factoryPreconditions = factoryPreconditions; + this.activator = activator; + this.factoryRegistrationWorker = Executors.newSingleThreadExecutor( + r -> new Thread(r, "ResourceResolverFactory registration/deregistration")); + } + + @Override + public void close() { + unregisterFactory(); + factoryRegistrationWorker.shutdown(); + try { + if (!factoryRegistrationWorker.awaitTermination(5, TimeUnit.SECONDS)) { + final List<Runnable> runnables = factoryRegistrationWorker.shutdownNow(); + if (runnables.size() >= 2) { + final Runnable unregisterTask = runnables.get(runnables.size() - 2); + unregisterTask.run(); + } + } + } catch (InterruptedException e) { + Thread.currentThread().interrupt(); + } + } + + /** + * Check the preconditions and if it changed, either register factory or unregister + */ + void maybeRegisterFactory(final String unavailableName, final String unavailableServicePid) { + if (!factoryRegistrationWorker.isShutdown()) { + LOG.debug("submitting maybeRegisterFactory"); + factoryRegistrationWorker.submit(() -> { + final boolean preconditionsOk = factoryPreconditions.checkPreconditions(unavailableName, unavailableServicePid); + if ( preconditionsOk && this.factoryRegistration == null ) { + // check system bundle state - if stopping, don't register new factory + final Bundle systemBundle = activator.getBundleContext().getBundle(Constants.SYSTEM_BUNDLE_LOCATION); + if ( systemBundle != null && systemBundle.getState() != Bundle.STOPPING ) { + withThreadName("ResourceResolverFactory registration", this::doRegisterFactory); + } + } else if ( !preconditionsOk && this.factoryRegistration != null ) { + LOG.debug("performing unregisterFactory via maybeRegisterFactory"); + withThreadName("ResourceResolverFactory deregistration", this::doUnregisterFactory); + } + }); + } + } + + void unregisterFactory() { + LOG.debug("submitting unregisterFactory"); + factoryRegistrationWorker.submit(() -> withThreadName("ResourceResolverFactory deregistration", + this::doUnregisterFactory)); + } + + /** + * Register the factory. + */ + private void doRegisterFactory() { + LOG.debug("performing registerFactory, factoryRegistration == {}", factoryRegistration); + if (this.factoryRegistration == null) { + this.factoryRegistration = new FactoryRegistration(activator.getBundleContext(), activator); + } + LOG.debug("finished performing registerFactory, factoryRegistration == {}", factoryRegistration); + } + + /** + * Unregister the factory (if registered). + */ + private void doUnregisterFactory() { + LOG.debug("performing unregisterFactory, factoryRegistration == {}", factoryRegistration); + if (this.factoryRegistration != null) { + this.factoryRegistration.unregister(); + this.factoryRegistration = null; + } + LOG.debug("finished performing unregisterFactory, factoryRegistration == {}", factoryRegistration); + } + + private static void withThreadName(String threadName, Runnable task) { + final String name = Thread.currentThread().getName(); Review Comment: I found it helpful to have the registration/deregistration reflected in the thread-name, because service registrations trigger further service registrations etc. So it helps understand, which changes in the system happened due to the registration/deregistration. Regarding the naming of the thread, yes the class-name as a prefix would work. De-facto, I am using the prefix "ResourceResolverFactory". I can incorporate that into the method, if you think it would be valuable. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
