content: /**
   * 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.activemq.transport.amqp.client;
  
  import java.io.IOException;
  
  import org.apache.activemq.transport.amqp.client.util.AsyncResult;
  import org.apache.qpid.proton.engine.Endpoint;
  import org.apache.qpid.proton.engine.EndpointState;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Abstract base for all AmqpResource implementations to extend.
   *
   * This abstract class wraps up the basic state management bits so that the concrete
   * object don't have to reproduce it.  Provides hooks for the subclasses to initialize
   * and shutdown.
   */
  public abstract class AmqpAbstractResource<E extends Endpoint> implements AmqpResource {
  
      private static final Logger LOG = LoggerFactory.getLogger(AmqpAbstractResource.class);
  
      protected AsyncResult openRequest;
      protected AsyncResult closeRequest;
  
      private AmqpValidator amqpStateInspector;
  
      private E endpoint;
  
      @Override
      public void open(AsyncResult request) {
          this.openRequest = request;
          doOpen();
          getEndpoint().setContext(this);
      }
  
      @Override
      public boolean isOpen() {
          return getEndpoint().getRemoteState() == EndpointState.ACTIVE;
      }
  
      @Override
      public void opened() {
          if (this.openRequest != null) {
              this.openRequest.onSuccess();
              this.openRequest = null;
          }
      }
  
      @Override
      public void detach(AsyncResult request) {
          // If already closed signal success or else the caller might never get notified.
          if (getEndpoint().getLocalState() == EndpointState.CLOSED ||
              getEndpoint().getRemoteState() == EndpointState.CLOSED) {
  
              if (getEndpoint().getLocalState() != EndpointState.CLOSED) {
                  doDetach();
                  getEndpoint().free();
              }
  
              request.onSuccess();
          } else {
              this.closeRequest = request;
              doDetach();
          }
      }
  
      @Override
      public void close(AsyncResult request) {
          // If already closed signal success or else the caller might never get notified.
          if (getEndpoint().getLocalState() == EndpointState.CLOSED ||
              getEndpoint().getRemoteState() == EndpointState.CLOSED) {
  
              if (getEndpoint().getLocalState() != EndpointState.CLOSED) {
                  doClose();
                  getEndpoint().free();
              }
  
              request.onSuccess();
          } else {
              this.closeRequest = request;
              doClose();
          }
      }
  
      @Override
      public boolean isClosed() {
          return getEndpoint().getLocalState() == EndpointState.CLOSED;
      }
  
      @Override
      public void closed() {
          getEndpoint().close();
          getEndpoint().free();
  
          if (this.closeRequest != null) {
              this.closeRequest.onSuccess();
              this.closeRequest = null;
          }
      }
  
      @Override
      public void failed() {
          failed(new Exception("Remote request failed."));
      }
  
      @Override
      public void failed(Exception cause) {
          if (openRequest != null) {
              if (endpoint != null) {
                  // TODO: if this is a producer/consumer link then we may only be detached,
                  // rather than fully closed, and should respond appropriately.
                  endpoint.close();
              }
              openRequest.onFailure(cause);
              openRequest = null;
          }
  
          if (closeRequest != null) {
              closeRequest.onFailure(cause);
              closeRequest = null;
          }
      }
  
      @Override
      public void remotelyClosed(AmqpConnection connection) {
          Exception error = AmqpSupport.convertToException(getEndpoint().getRemoteCondition());
  
          if (endpoint != null) {
              // TODO: if this is a producer/consumer link then we may only be detached,
              // rather than fully closed, and should respond appropriately.
              endpoint.close();
          }
  
          LOG.info("Resource {} was remotely closed", this);
  
          connection.fireClientException(error);
      }
  
      @Override
      public void locallyClosed(AmqpConnection connection, Exception error) {
          if (endpoint != null) {
              // TODO: if this is a producer/consumer link then we may only be detached,
              // rather than fully closed, and should respond appropriately.
              endpoint.close();
          }
  
          LOG.info("Resource {} was locally closed", this);
  
          connection.fireClientException(error);
      }
  
      public E getEndpoint() {
          return this.endpoint;
      }
  
      public void setEndpoint(E endpoint) {
          this.endpoint = endpoint;
      }
  
      public AmqpValidator getStateInspector() {
          return amqpStateInspector;
      }
  
      public void setStateInspector(AmqpValidator stateInspector) {
          if (stateInspector == null) {
              stateInspector = new AmqpValidator();
          }
  
          this.amqpStateInspector = stateInspector;
      }
  
      public EndpointState getLocalState() {
          if (getEndpoint() == null) {
              return EndpointState.UNINITIALIZED;
          }
          return getEndpoint().getLocalState();
      }
  
      public EndpointState getRemoteState() {
          if (getEndpoint() == null) {
              return EndpointState.UNINITIALIZED;
          }
          return getEndpoint().getRemoteState();
      }
  
      public boolean hasRemoteError() {
          return getEndpoint().getRemoteCondition().getCondition() != null;
      }
  
      @Override
      public void processRemoteOpen(AmqpConnection connection) throws IOException {
          doOpenInspection();
          doOpenCompletion();
      }
  
      @Override
      public void processRemoteDetach(AmqpConnection connection) throws IOException {
          doDetachedInspection();
          if (isAwaitingClose()) {
              LOG.debug("{} is now closed: ", this);
              closed();
          } else {
              remotelyClosed(connection);
          }
      }
  
      @Override
      public void processRemoteClose(AmqpConnection connection) throws IOException {
          doClosedInspection();
          if (isAwaitingClose()) {
              LOG.debug("{} is now closed: ", this);
              closed();
          } else if (isAwaitingOpen()) {
              // Error on Open, create exception and signal failure.
              LOG.warn("Open of {} failed: ", this);
              Exception openError;
              if (hasRemoteError()) {
                  openError = AmqpSupport.convertToException(getEndpoint().getRemoteCondition());
              } else {
                  openError = getOpenAbortException();
              }
  
              failed(openError);
          } else {
              remotelyClosed(connection);
          }
      }
  
      @Override
      public void processDeliveryUpdates(AmqpConnection connection) throws IOException {
      }
  
      @Override
      public void processFlowUpdates(AmqpConnection connection) throws IOException {
      }
  
      /**
       * Perform the open operation on the managed endpoint.  A subclass may
       * override this method to provide additional open actions or configuration
       * updates.
       */
      protected void doOpen() {
          getEndpoint().open();
      }
  
      /**
       * Perform the close operation on the managed endpoint.  A subclass may
       * override this method to provide additional close actions or alter the
       * standard close path such as endpoint detach etc.
       */
      protected void doClose() {
          getEndpoint().close();
      }
  
      /**
       * Perform the detach operation on the managed endpoint.
       *
       * By default this method throws an UnsupportedOperationException, a subclass
       * must implement this and do a detach if its resource supports that.
       */
      protected void doDetach() {
          throw new UnsupportedOperationException("Endpoint cannot be detached.");
      }
  
      /**
       * Complete the open operation on the managed endpoint. A subclass may
       * override this method to provide additional verification actions or configuration
       * updates.
       */
      protected void doOpenCompletion() {
          LOG.debug("{} is now open: ", this);
          opened();
      }
  
      /**
       * When aborting the open operation, and there isnt an error condition,
       * provided by the peer, the returned exception will be used instead.
       * A subclass may override this method to provide alternative behaviour.
       */
      protected Exception getOpenAbortException() {
          return new IOException("Open failed unexpectedly.");
      }
  
      protected abstract void doOpenInspection();
      protected abstract void doClosedInspection();
  
      protected void doDetachedInspection() {}
  
      //----- Private implementation utility methods ---------------------------//
  
      private boolean isAwaitingOpen() {
          return this.openRequest != null;
      }
  
      private boolean isAwaitingClose() {
          return this.closeRequest != null;
      }
  }
  