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.cassandra.distributed.impl;
  
  import java.io.ByteArrayInputStream;
  import java.io.ByteArrayOutputStream;
  import java.io.IOException;
  import java.io.ObjectInputStream;
  import java.io.ObjectOutputStream;
  import java.io.Serializable;
  import java.lang.reflect.InvocationTargetException;
  import java.lang.reflect.Method;
  import java.net.URLClassLoader;
  import java.util.concurrent.ExecutionException;
  import java.util.concurrent.Executor;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Future;
  import java.util.concurrent.LinkedBlockingQueue;
  import java.util.concurrent.ThreadFactory;
  import java.util.concurrent.ThreadPoolExecutor;
  import java.util.concurrent.TimeUnit;
  import java.util.function.BiConsumer;
  import java.util.function.BiFunction;
  import java.util.function.Consumer;
  import java.util.function.Function;
  import java.util.function.Supplier;
  
  import org.slf4j.LoggerFactory;
  
  import ch.qos.logback.classic.LoggerContext;
  import io.netty.util.concurrent.FastThreadLocal;
  import org.apache.cassandra.concurrent.ExecutorFactory;
  import org.apache.cassandra.distributed.api.IIsolatedExecutor;
  import org.apache.cassandra.utils.ExecutorUtils;
  import org.apache.cassandra.utils.Throwables;
  
  import static java.util.concurrent.TimeUnit.SECONDS;
  
  public class IsolatedExecutor implements IIsolatedExecutor
  {
      final ExecutorService isolatedExecutor;
      private final String name;
      final ClassLoader classLoader;
      private final DynamicFunction<Serializable> transfer;
      private final ShutdownExecutor shutdownExecutor;
  
      public static final ShutdownExecutor DEFAULT_SHUTDOWN_EXECUTOR = (name, classLoader, shuttingDown, onTermination) -> {
          /* Use a thread pool with a core pool size of zero to terminate the thread as soon as possible
           ** so the instance class loader can be garbage collected.  Uses a custom thread factory
           ** rather than NamedThreadFactory to avoid calling FastThreadLocal.removeAll() in 3.0 and up
           ** as it was observed crashing during test failures and made it harder to find the real cause.
           */
          ThreadFactory threadFactory = (Runnable r) -> {
              Thread t = new Thread(r, name + "_shutdown");
              t.setDaemon(true);
              return t;
          };
  
          ExecutorService shutdownExecutor = new ThreadPoolExecutor(0, Integer.MAX_VALUE, 0, SECONDS,
                                                                    new LinkedBlockingQueue<>(), threadFactory);
          return shutdownExecutor.submit(() -> {
              try
              {
                  ExecutorUtils.awaitTermination(60, TimeUnit.SECONDS, shuttingDown);
                  return onTermination.call();
              }
              finally
              {
                  shutdownExecutor.shutdownNow();
              }
          });
      };
  
      // retained for backwards compatibility
      @SuppressWarnings("unused")
      public IsolatedExecutor(String name, ClassLoader classLoader, ExecutorFactory executorFactory)
      {
          this(name, classLoader, executorFactory.pooled("isolatedExecutor", Integer.MAX_VALUE), DEFAULT_SHUTDOWN_EXECUTOR);
      }
  
      // retained for backwards compatibility
      @SuppressWarnings("unused")
      public IsolatedExecutor(String name, ClassLoader classLoader, ExecutorService executorService)
      {
          this(name, classLoader, executorService, DEFAULT_SHUTDOWN_EXECUTOR);
      }
  
      IsolatedExecutor(String name, ClassLoader classLoader, ExecutorService executorService, ShutdownExecutor shutdownExecutor)
      {
          this.name = name;
          this.isolatedExecutor = executorService;
          this.classLoader = classLoader;
          this.transfer = transferTo(classLoader);
          this.shutdownExecutor = shutdownExecutor;
      }
  
      protected IsolatedExecutor(IsolatedExecutor from, ExecutorService executor)
      {
          this.name = from.name;
          this.isolatedExecutor = executor;
          this.classLoader = from.classLoader;
          this.transfer = from.transfer;
          this.shutdownExecutor = from.shutdownExecutor;
      }
  
      public IIsolatedExecutor with(ExecutorService executor)
      {
          return new IsolatedExecutor(this, executor);
      }
  
      public Future<Void> shutdown()
      {
          isolatedExecutor.shutdown();
          return shutdownExecutor.shutdown(name, classLoader, isolatedExecutor, () -> {
  
              // Shutdown logging last - this is not ideal as the logging subsystem is initialized
              // outsize of this class, however doing it this way provides access to the full
              // logging system while termination is taking place.
              LoggerContext loggerContext = (LoggerContext) LoggerFactory.getILoggerFactory();
              loggerContext.stop();
  
              FastThreadLocal.destroy();
  
              // Close the instance class loader after shutting down the isolatedExecutor and logging
              // in case error handling triggers loading additional classes
              ((URLClassLoader) classLoader).close();
              return null;
          });
      }
  
      public <O> Supplier<Future<O>> supplyAsync(SerializableSupplier<O> call) { return () -> isolatedExecutor.submit(call::get); }
      public <O> Supplier<O> supplySync(SerializableSupplier<O> call) { return () -> waitOn(supplyAsync(call).get()); }
  
      public <O> CallableNoExcept<Future<O>> async(CallableNoExcept<O> call) { return () -> isolatedExecutor.submit(call); }
      public <O> CallableNoExcept<O> sync(CallableNoExcept<O> call) { return () -> waitOn(async(call).call()); }
  
      public CallableNoExcept<Future<?>> async(Runnable run) { return () -> isolatedExecutor.submit(run); }
      public Runnable sync(Runnable run) { return () -> waitOn(async(run).call()); }
  
      public <I> Function<I, Future<?>> async(Consumer<I> consumer) { return (a) -> isolatedExecutor.submit(() -> consumer.accept(a)); }
      public <I> Consumer<I> sync(Consumer<I> consumer) { return (a) -> waitOn(async(consumer).apply(a)); }
  
      public <I1, I2> BiFunction<I1, I2, Future<?>> async(BiConsumer<I1, I2> consumer) { return (a, b) -> isolatedExecutor.submit(() -> consumer.accept(a, b)); }
      public <I1, I2> BiConsumer<I1, I2> sync(BiConsumer<I1, I2> consumer) { return (a, b) -> waitOn(async(consumer).apply(a, b)); }
  
      public <I1, I2, I3> TriFunction<I1, I2, I3, Future<?>> async(TriConsumer<I1, I2, I3> consumer) { return (a, b, c) -> isolatedExecutor.submit(() -> consumer.accept(a, b, c)); }
      public <I1, I2, I3> TriConsumer<I1, I2, I3> sync(TriConsumer<I1, I2, I3> consumer) { return (a, b, c) -> waitOn(async(consumer).apply(a, b, c)); }
  
      public <I, O> Function<I, Future<O>> async(Function<I, O> f) { return (a) -> isolatedExecutor.submit(() -> f.apply(a)); }
      public <I, O> Function<I, O> sync(Function<I, O> f) { return (a) -> waitOn(async(f).apply(a)); }
  
      public <I1, I2, O> BiFunction<I1, I2, Future<O>> async(BiFunction<I1, I2, O> f) { return (a, b) -> isolatedExecutor.submit(() -> f.apply(a, b)); }
      public <I1, I2, O> BiFunction<I1, I2, O> sync(BiFunction<I1, I2, O> f) { return (a, b) -> waitOn(async(f).apply(a, b)); }
  
      public <I1, I2, I3, O> TriFunction<I1, I2, I3, Future<O>> async(TriFunction<I1, I2, I3, O> f) { return (a, b, c) -> isolatedExecutor.submit(() -> f.apply(a, b, c)); }
      public <I1, I2, I3, O> TriFunction<I1, I2, I3, O> sync(TriFunction<I1, I2, I3, O> f) { return (a, b, c) -> waitOn(async(f).apply(a, b, c)); }
  
      public <I1, I2, I3, I4, O> QuadFunction<I1, I2, I3, I4, Future<O>> async(QuadFunction<I1, I2, I3, I4, O> f) { return (a, b, c, d) -> isolatedExecutor.submit(() -> f.apply(a, b, c, d)); }
      public <I1, I2, I3, I4, O> QuadFunction<I1, I2, I3, I4, O> sync(QuadFunction<I1, I2, I3, I4, O> f) { return (a, b, c, d) -> waitOn(async(f).apply(a, b, c, d)); }
  
      public <I1, I2, I3, I4, I5, O> QuintFunction<I1, I2, I3, I4, I5, Future<O>> async(QuintFunction<I1, I2, I3, I4, I5, O> f) { return (a, b, c, d, e) -> isolatedExecutor.submit(() -> f.apply(a, b, c, d, e)); }
      public <I1, I2, I3, I4, I5, O> QuintFunction<I1, I2, I3, I4, I5, O> sync(QuintFunction<I1, I2, I3, I4, I5, O> f) { return (a, b, c, d,e ) -> waitOn(async(f).apply(a, b, c, d, e)); }
  
      public Executor executor()
      {
          return isolatedExecutor;
      }
  
      public <T extends Serializable> T transfer(T in)
      {
          return transfer.apply(in);
      }
  
      public static <T extends Serializable> T transferAdhoc(T object, ClassLoader classLoader)
      {
          try
          {
              return transferOneObjectAdhoc(object, classLoader, lookupDeserializeOneObject(classLoader));
          }
          catch (IllegalAccessException | InvocationTargetException e)
          {
              throw new RuntimeException(e);
          }
      }
  
      public static <T extends Serializable> T transferAdhocPropagate(T object, ClassLoader classLoader) throws InvocationTargetException, IllegalAccessException
      {
          return transferOneObjectAdhoc(object, classLoader, lookupDeserializeOneObject(classLoader));
      }
  
      private static final SerializableFunction<byte[], Object> DESERIALIZE_ONE_OBJECT = IsolatedExecutor::deserializeOneObject;
  
      public static DynamicFunction<Serializable> transferTo(ClassLoader classLoader)
      {
          SerializableFunction<byte[], Object> deserializeOneObject = transferAdhoc(DESERIALIZE_ONE_OBJECT, classLoader);
          return new DynamicFunction<Serializable>()
          {
              public <T extends Serializable> T apply(T in)
              {
                  return (T) deserializeOneObject.apply(serializeOneObject(in));
              }
          };
      }
  
      private static <T extends Serializable> T transferOneObjectAdhoc(T object, ClassLoader classLoader, Method deserializeOnInstance) throws IllegalAccessException, InvocationTargetException
      {
          byte[] bytes = serializeOneObject(object);
          Object onInstance = deserializeOnInstance.invoke(null, bytes);
          if (onInstance.getClass().getClassLoader() != classLoader)
              throw new IllegalStateException(onInstance + " seemingly from wrong class loader: " + onInstance.getClass().getClassLoader() + ", but expected " + classLoader);
  
          return (T) onInstance;
      }
  
      private static Method lookupDeserializeOneObject(ClassLoader classLoader)
      {
          try
          {
              return classLoader.loadClass(IsolatedExecutor.class.getName()).getDeclaredMethod("deserializeOneObject", byte[].class);
          }
          catch (ClassNotFoundException | NoSuchMethodException e)
          {
              throw new RuntimeException(e);
          }
      }
  
      @SuppressWarnings("unused") // called through method invocation
      public static Object deserializeOneObject(byte[] bytes)
      {
          try (ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
               ObjectInputStream ois = new ObjectInputStream(bais))
          {
              return ois.readObject();
          }
          catch (IOException | ClassNotFoundException e)
          {
              throw new RuntimeException(e);
          }
      }
  
      private static byte[] serializeOneObject(Object object)
      {
          try (ByteArrayOutputStream baos = new ByteArrayOutputStream();
               ObjectOutputStream oos = new ObjectOutputStream(baos))
          {
              oos.writeObject(object);
              oos.close();
              return baos.toByteArray();
          }
          catch (IOException e)
          {
              throw new RuntimeException(e);
          }
      }
  
      public static <T> T waitOn(Future<T> f)
      {
          try
          {
              return f.get();
          }
          catch (InterruptedException e)
          {
              Thread.currentThread().interrupt();
              throw Throwables.throwAsUncheckedException(e);
          }
          catch (ExecutionException e)
          {
              throw Throwables.throwAsUncheckedException(e.getCause());
          }
      }
  
  }
  