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.concurrent;
  
  import java.util.concurrent.Callable;
  
  import org.apache.cassandra.concurrent.DebuggableTask.RunnableDebuggableTask;
  import org.apache.cassandra.utils.Shared;
  import org.apache.cassandra.utils.WithResources;
  import org.apache.cassandra.utils.concurrent.RunnableFuture;
  
  import static org.apache.cassandra.concurrent.FutureTask.callable;
  import static org.apache.cassandra.utils.Shared.Recursive.INTERFACES;
  import static org.apache.cassandra.utils.Shared.Scope.SIMULATION;
  
  /**
   * A simple mechanism to impose our desired semantics on the execution of a task without requiring a specialised
   * executor service. We wrap tasks in a suitable {@link FutureTask} or encapsulating {@link Runnable}.
   * <p>
   * The encapsulations handle any exceptions in our standard way, as well as ensuring {@link ExecutorLocals} are
   * propagated in the case of {@link #localAware()}
   */
  @Shared(scope = SIMULATION, inner = INTERFACES)
  public interface TaskFactory
  {
      Runnable toExecute(Runnable runnable);
      <T> RunnableFuture<T> toSubmit(Runnable runnable);
      <T> RunnableFuture<T> toSubmit(Runnable runnable, T result);
      <T> RunnableFuture<T> toSubmit(Callable<T> callable);
  
      Runnable toExecute(WithResources withResources, Runnable runnable);
      <T> RunnableFuture<T> toSubmit(WithResources withResources, Runnable runnable);
      <T> RunnableFuture<T> toSubmit(WithResources withResources, Runnable runnable, T result);
      <T> RunnableFuture<T> toSubmit(WithResources withResources, Callable<T> callable);
  
      static TaskFactory standard() { return Standard.INSTANCE; }
      static TaskFactory localAware() { return LocalAware.INSTANCE; }
  
      class Standard implements TaskFactory
      {
          static final Standard INSTANCE = new Standard();
          protected Standard() {}
  
          @Override
          public Runnable toExecute(Runnable runnable)
          {
              return ExecutionFailure.suppressing(runnable);
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(Runnable runnable)
          {
              return newTask(callable(runnable));
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(Runnable runnable, T result)
          {
              return newTask(callable(runnable, result));
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(Callable<T> callable)
          {
              return newTask(callable);
          }
  
          @Override
          public Runnable toExecute(WithResources withResources, Runnable runnable)
          {
              return ExecutionFailure.suppressing(withResources, runnable);
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(WithResources withResources, Runnable runnable)
          {
              return withResources.isNoOp() ? newTask(runnable)
                                            : newTask(withResources, runnable);
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(WithResources withResources, Runnable runnable, T result)
          {
              return withResources.isNoOp() ? newTask(callable(runnable, result))
                                            : newTask(withResources, callable(runnable, result));
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(WithResources withResources, Callable<T> callable)
          {
              return withResources.isNoOp() ? newTask(callable)
                                            : newTask(withResources, callable);
          }
  
          protected <T> RunnableFuture<T> newTask(Runnable task)
          {
              return new FutureTask<>(task);
          }
  
          protected <T> RunnableFuture<T> newTask(Callable<T> call)
          {
              return new FutureTask<>(call);
          }
  
          protected <T> RunnableFuture<T> newTask(WithResources withResources, Runnable task)
          {
              return new FutureTaskWithResources<>(withResources, task);
          }
  
          protected <T> RunnableFuture<T> newTask(WithResources withResources, Callable<T> call)
          {
              return new FutureTaskWithResources<>(withResources, call);
          }
      }
  
      class LocalAware extends Standard
      {
          static final LocalAware INSTANCE = new LocalAware();
  
          protected LocalAware() {}
  
          @Override
          public Runnable toExecute(Runnable runnable)
          {
              if (runnable instanceof RunnableDebuggableTask)
                  return ExecutionFailure.suppressingDebuggable(ExecutorLocals.propagate(), (RunnableDebuggableTask) runnable);
  
              // no reason to propagate exception when it is inaccessible to caller
              return ExecutionFailure.suppressing(ExecutorLocals.propagate(), runnable);
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(Runnable runnable)
          {
              return super.toSubmit(ExecutorLocals.propagate(), runnable);
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(Runnable runnable, T result)
          {
              return super.toSubmit(ExecutorLocals.propagate(), runnable, result);
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(Callable<T> callable)
          {
              return super.toSubmit(ExecutorLocals.propagate(), callable);
          }
  
          @Override
          public Runnable toExecute(WithResources withResources, Runnable runnable)
          {
              return ExecutionFailure.suppressing(withLocals(withResources), runnable);
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(WithResources withResources, Runnable runnable)
          {
              return super.toSubmit(withLocals(withResources), runnable);
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(WithResources withResources, Runnable runnable, T result)
          {
              return super.toSubmit(withLocals(withResources), runnable, result);
          }
  
          @Override
          public <T> RunnableFuture<T> toSubmit(WithResources withResources, Callable<T> callable)
          {
              return super.toSubmit(withLocals(withResources), callable);
          }
  
          private static WithResources withLocals(WithResources withResources)
          {
              return withResources instanceof ExecutorLocals ? withResources : ExecutorLocals.propagate().and(withResources);
          }
      }
  
  }
  