CancellableCompositeTask.java

/*
** Module   : CancellableCompositeTask.java
** Abstract : Cancellable composite FutureTask.
**
** Copyright (c) 2025, Golden Code Development Corporation.
**
** -#- -I- --Date-- ---------------------------------Description----------------------------------
** 001 GBB 20250122 Created initial version.
*/
/*
** This program is free software: you can redistribute it and/or modify
** it under the terms of the GNU Affero General Public License as
** published by the Free Software Foundation, either version 3 of the
** License, or (at your option) any later version.
**
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU Affero General Public License for more details.
**
** You may find a copy of the GNU Affero GPL version 3 at the following
** location: https://www.gnu.org/licenses/agpl-3.0.en.html
**
** Additional terms under GNU Affero GPL version 3 section 7:
**
**   Under Section 7 of the GNU Affero GPL version 3, the following additional
**   terms apply to the works covered under the License.  These additional terms
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*/

package com.goldencode.p2j.util.appserver;

import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;

/** Cancellable composite FutureTask */
class CancellableCompositeTask<V>
extends FutureTask<V>
{
   /** Generator for unique ids for the tasks. */
   private static final AtomicInteger taskIdGenerator = new AtomicInteger(1);

   /** The callable to be executed. */
   private final CancellableCallable<V> callable;

   /** The task ID. */
   private final int taskId;

   /** The request ID. */
   private final Integer requestId;

   /** The type of the task. */
   private final MultiSessionTaskType type;

   /**
    * Package-private constructor.
    * 
    * @param    callable
    *           The callable to be executed.
    * @param    type
    *           The type of the callable.
    */
   CancellableCompositeTask(CancellableCallable<V> callable, MultiSessionTaskType type)
   {
      this(callable, type, null);
   }

   /**
    * Package-private constructor.
    *
    * @param    callable
    *           The callable to be executed.
    * @param    type
    *           The type of the callable.
    * @param    requestId
    *           The request ID.
    */
   CancellableCompositeTask(CancellableCallable<V> callable, MultiSessionTaskType type, Integer requestId)
   {
      super(callable);
      this.callable = callable;
      this.taskId = taskIdGenerator.getAndIncrement();
      this.requestId = requestId;
      this.type = type;
   }

   /**
    * If not already completed, completes this CompletableFuture with a {@link CancellationException}.
    * 
    * @param    mayInterruptIfRunning
    *           Flag to interrupt to thread.
    * 
    * @return   {@code true} if this task is now cancelled
    */
   @Override
   public boolean cancel(boolean mayInterruptIfRunning)
   {
      callable.cancel(CancelCause.REQUEST_TIMEOUT);
      return super.cancel(mayInterruptIfRunning);
   }

   /**
    * If not already completed, completes this CompletableFuture with a {@link CancellationException}.
    *
    * @param    mayInterruptIfRunning
    *           Flag to interrupt to thread.
    * @param    cancelCause
    *           The cause for the cancel.
    *
    * @return   {@code true} if this task is now cancelled
    */
   public boolean cancel(boolean mayInterruptIfRunning, CancelCause cancelCause)
   {
      callable.cancel(cancelCause);
      return super.cancel(mayInterruptIfRunning);
   }

   /**
    * Checks if the argument object represents the same task, identified by the taskId.
    *
    * @param    o
    *           The object to compare to.
    *
    * @return   <code>true</code> if it's the same instance or taskId is the same.
    *           <code>false</code> otherwise.
    */
   @Override
   public boolean equals(Object o)
   {
      if (this == o)
      {
         return true;
      }
      if (o == null || getClass() != o.getClass())
      {
         return false;
      }
      CancellableCompositeTask<?> that = (CancellableCompositeTask<?>) o;
      return taskId == that.taskId;
   }

   /**
    * Returns the hash of the fields uniquely identifying the object.
    *
    * @return   See above.
    */
   @Override
   public int hashCode()
   {
      return Objects.hash(taskId);
   }

   /**
    * Returns the string representation.
    *
    * @return   See above.
    */
   @Override
   public String toString()
   {
      return "CancellableCompositeTask{" +
         "taskId=" + taskId +
         ", requestId=" + requestId +
         ", type=" + type +
         '}';
   }
   
   /**
    * Interrupts the executor thread where the MSA task is running.
    */
   public void sendStop()
   {
      sendStop(CancelCause.SEND_STOP);
   }
   
   /**
    * Interrupts the executor thread where the MSA task is running.
    * 
    * @param    cancelCause
    *           The cause for the cancel.
    */
   public void sendStop(CancelCause cancelCause)
   {
      callable.sendStop(cancelCause);
   }

   /**
    * Getter for {@link #taskId}
    * 
    * @return   See above.
    */
   int getTaskId()
   {
      return taskId;
   }

   /**
    * Getter for {@link #type}
    *
    * @return   See above.
    */
   MultiSessionTaskType getType()
   {
      return type;
   }

   /**
    * Returns a thread-safe flag indicating if the MSA task is running.
    *
    * @return   See above.
    */
   AtomicBoolean getRunningSupplier()
   {
      return callable.getIsRunningSupplier();
   }
   
   /**
    * Returns the cause of the cancel, <code>null</code> when the callable is not cancelled.
    *
    * @return   See above.
    */
   CancelCause getCancelCause()
   {
      return callable.getCancelCause();
   }
}