content: /*
   * Copyright (c) 2024, Alibaba Cloud;
   * 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 com.aliyun.dataworks.client.utils.spark.command;
  
  import java.io.IOException;
  import java.util.List;
  import java.util.concurrent.CopyOnWriteArrayList;
  import java.util.concurrent.atomic.AtomicReference;
  import java.util.logging.Level;
  import java.util.logging.Logger;
  
  abstract class AbstractAppHandle implements SparkAppHandle {
  
      private static final Logger LOG = Logger.getLogger(AbstractAppHandle.class.getName());
  
      private final LauncherServer server;
  
      private LauncherServer.ServerConnection connection;
      private List<Listener> listeners;
      private AtomicReference<State> state;
      private volatile String appId;
      private volatile boolean disposed;
  
      protected AbstractAppHandle(LauncherServer server) {
          this.server = server;
          this.state = new AtomicReference<>(State.UNKNOWN);
      }
  
      @Override
      public synchronized void addListener(SparkAppHandle.Listener l) {
          if (listeners == null) {
              listeners = new CopyOnWriteArrayList<>();
          }
          listeners.add(l);
      }
  
      @Override
      public SparkAppHandle.State getState() {
          return state.get();
      }
  
      @Override
      public String getAppId() {
          return appId;
      }
  
      @Override
      public void stop() {
          CommandBuilderUtils.checkState(connection != null, "Application is still not connected.");
          try {
              connection.send(new LauncherProtocol.Stop());
          } catch (IOException ioe) {
              throw new RuntimeException(ioe);
          }
      }
  
      @Override
      public synchronized void disconnect() {
          if (connection != null && connection.isOpen()) {
              try {
                  connection.close();
              } catch (IOException ioe) {
                  // no-op.
              }
          }
          dispose();
      }
  
      void setConnection(LauncherServer.ServerConnection connection) {
          this.connection = connection;
      }
  
      LauncherConnection getConnection() {
          return connection;
      }
  
      boolean isDisposed() {
          return disposed;
      }
  
      /**
       * Mark the handle as disposed, and set it as LOST in case the current state is not final.
       * <p>
       * This method should be called only when there's a reasonable expectation that the communication with the child
       * application is not needed anymore, either because the code managing the handle has said so, or because the child
       * application is finished.
       */
      synchronized void dispose() {
          if (!isDisposed()) {
              // First wait for all data from the connection to be read. Then unregister the handle.
              // Otherwise, unregistering might cause the server to be stopped and all child connections
              // to be closed.
              if (connection != null) {
                  try {
                      connection.waitForClose();
                  } catch (IOException ioe) {
                      // no-op.
                  }
              }
              server.unregister(this);
  
              // Set state to LOST if not yet final.
              setState(State.LOST, false);
              this.disposed = true;
          }
      }
  
      void setState(SparkAppHandle.State s) {
          setState(s, false);
      }
  
      void setState(SparkAppHandle.State s, boolean force) {
          if (force) {
              state.set(s);
              fireEvent(false);
              return;
          }
  
          State current = state.get();
          while (!current.isFinal()) {
              if (state.compareAndSet(current, s)) {
                  fireEvent(false);
                  return;
              }
              current = state.get();
          }
  
          if (s != State.LOST) {
              LOG.log(Level.WARNING, "Backend requested transition from final state {0} to {1}.",
                  new Object[] {current, s});
          }
      }
  
      void setAppId(String appId) {
          this.appId = appId;
          fireEvent(true);
      }
  
      private void fireEvent(boolean isInfoChanged) {
          if (listeners != null) {
              for (Listener l : listeners) {
                  if (isInfoChanged) {
                      l.infoChanged(this);
                  } else {
                      l.stateChanged(this);
                  }
              }
          }
      }
  
  }
  