content: package act.app;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2017 ActFramework
   * %%
   * 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.
   * #L%
   */
  
  import act.Destroyable;
  import act.app.event.SysEventId;
  import org.osgl.$;
  import org.osgl.util.C;
  
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  import java.util.concurrent.ConcurrentMap;
  import javax.enterprise.context.ApplicationScoped;
  
  /**
   * provides service for app to get singleton instance by type
   */
  public class SingletonRegistry extends AppServiceBase<SingletonRegistry> {
  
      private ConcurrentMap<Class<?>, Object> registry = new ConcurrentHashMap<Class<?>, Object>();
      private ConcurrentHashMap<Class<?>, Class<?>> preRegistry = new ConcurrentHashMap<>();
      private boolean batchRegistered = false;
  
      SingletonRegistry(App app) {
          super(app, false);
      }
  
      synchronized void register(final Class<?> singletonClass) {
          if (isTraceEnabled()) {
              trace("register " + singletonClass);
          }
          if (!batchRegistered) {
              if (preRegistry.isEmpty()) {
                  trace("preRegistry is empty");
                  if (isTraceEnabled()) {
                      trace("Add [%s] to preRegistry", singletonClass);
                  }
                  preRegistry.put(singletonClass, singletonClass);
                  app().jobManager().on(SysEventId.DEPENDENCY_INJECTOR_PROVISIONED, "register-singleton-instances", new Runnable() {
                      @Override
                      public void run() {
                          doRegister();
                      }
                  }, true);
              }
          } else {
              register(singletonClass, app().getInstance(singletonClass));
          }
      }
  
      public Iterable<String> typeNames() {
          return C.list(registry.keySet()).map($.F.asString());
      }
  
      public void register(Class singletonClass, Object singleton) {
          if (isTraceEnabled()) {
              trace("direct register " + singletonClass);
          }
          registry.put(singletonClass, singleton);
      }
  
      <T> T get(Class<T> singletonClass) {
          return $.cast(registry.get(singletonClass));
      }
  
      @Override
      protected void releaseResources() {
          Destroyable.Util.tryDestroyAll(registry.values(), ApplicationScoped.class);
          registry.clear();
      }
  
      private void doRegister() {
          boolean traceEnabled = isTraceEnabled();
          if (traceEnabled) {
              trace("doRegister");
          }
          batchRegistered = true;
          for (Map.Entry<Class<?>, Class<?>> entry: preRegistry.entrySet()) {
              Class<?> c = entry.getKey();
              if (traceEnabled) {
                  trace("doRegister on " + c);
              }
              registry.put(c, app().getInstance(c));
          }
          preRegistry.clear();
      }
  }
  