Task.h

// -*- tab-width: 2; indent-tabs-mode: nil; coding: utf-8-with-signature -*-
//-----------------------------------------------------------------------------
// Copyright 2000-2026 CEA (www.cea.fr) IFPEN (www.ifpenergiesnouvelles.com)
// See the top-level COPYRIGHT file for details.
// SPDX-License-Identifier: Apache-2.0
//-----------------------------------------------------------------------------
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/* Task.h                                                      (C) 2000-2025 */
/*                                                                           */
/* Classes managing concurrent tasks.                                        */
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#ifndef ARCCORE_BASE_TASK_H
#define ARCCORE_BASE_TASK_H
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#include "arccore/base/RangeFunctor.h"
#include "arccore/base/FatalErrorException.h"
#include "arccore/base/ForLoopTraceInfo.h"
#include "arccore/base/ParallelLoopOptions.h"
#include "arccore/base/ForLoopRunInfo.h"
 
#include "arccore/concurrency/ConcurrencyGlobal.h"
 
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namespace Arcane
{
 
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/*
 * TODO:
 * - Check memory leaks
 * - CLEARLY INDICATE THAT A TASK MUST NOT BE USED AFTER THE WAIT!!!
 * - Look into exception mechanism.
 * - Overload For and Foreach without specifying the block_size
 */
 
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/*!
 * \brief Execution context of a task.
 * \ingroup Concurrency
 */
class ARCCORE_CONCURRENCY_EXPORT TaskContext
{
 public:
 
  explicit TaskContext(ITask* atask)
  : m_task(atask)
  {}
 
 public:
 
  //! Current task.
  ITask* task() const { return m_task; }
 
 private:
 
  ITask* m_task;
};
 
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/*!
 * \internal
 * \brief Interface for a task functor.
 * \ingroup Concurrency
 */
class ARCCORE_CONCURRENCY_EXPORT ITaskFunctor
{
 public:
 
  virtual ~ITaskFunctor() = default;
 
 protected:
 
  ITaskFunctor(const ITaskFunctor&) = default;
  ITaskFunctor() = default;
 
 public:
 
  //! Executes the associated method
  virtual void executeFunctor(const TaskContext& tc) = 0;
  virtual ITaskFunctor* clone(void* buffer, Integer size) = 0;
};
 
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/*!
 * \internal
 * \brief Functor without arguments for a task.
 * \ingroup Concurrency
 */
template <typename InstanceType>
class TaskFunctor
: public ITaskFunctor
{
 public:
 
  typedef void (InstanceType::*FunctorType)();
 
 public:
 
  TaskFunctor(InstanceType* instance, FunctorType func)
  : m_instance(instance)
  , m_function(func)
  {
  }
  TaskFunctor(const TaskFunctor& rhs) = default;
  TaskFunctor& operator=(const TaskFunctor& rhs) = delete;
 
 public:
 
  //! Executes the associated method
  void executeFunctor(const TaskContext& /*tc*/) override
  {
    (m_instance->*m_function)();
  }
  ITaskFunctor* clone(void* buffer, Integer size) override
  {
    if (sizeof(*this) > (size_t)size)
      ARCCORE_FATAL("INTERNAL: task functor buffer is too small");
    return new (buffer) TaskFunctor<InstanceType>(*this);
  }
 
 private:
 
  InstanceType* m_instance;
  FunctorType m_function;
};
 
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/*!
 * \internal
 * \brief Functor for a task taking a TaskContext as an argument.
 * \ingroup Concurrency
 */
template <typename InstanceType>
class TaskFunctorWithContext
: public ITaskFunctor
{
 public:
 
  typedef void (InstanceType::*FunctorType)(const TaskContext& tc);
 
 public:
 
  TaskFunctorWithContext(InstanceType* instance, FunctorType func)
  : ITaskFunctor()
  , m_instance(instance)
  , m_function(func)
  {
  }
 
 public:
 
  //! Executes the associated method
  void executeFunctor(const TaskContext& tc) override
  {
    (m_instance->*m_function)(tc);
  }
  ITaskFunctor* clone(void* buffer, Integer size) override
  {
    if (sizeof(*this) > (size_t)size)
      ARCCORE_FATAL("INTERNAL: task functor buffer is too small");
    return new (buffer) TaskFunctorWithContext<InstanceType>(*this);
  }
 
 private:
 
  InstanceType* m_instance = nullptr;
  FunctorType m_function;
};
 
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/*!
 * \ingroup Concurrency
 * \brief Interface for a concurrent task.
 *
 * Tasks are created via TaskFactory.
 */
class ARCCORE_CONCURRENCY_EXPORT ITask
{
  friend class TaskFactory;
 
 public:
 
  virtual ~ITask() = default;
 
 public:
 
  /*!
   * \brief Launches the task and blocks until it finishes.
   *
   * After calling this function, the task is destroyed and must not
   * be used again.
   */
  virtual void launchAndWait() = 0;
  /*!
   * \brief Launches the child tasks \a tasks and blocks
   * until they finish.
   */
  virtual void launchAndWait(ConstArrayView<ITask*> tasks) = 0;
 
 protected:
 
  virtual ITask* _createChildTask(ITaskFunctor* functor) = 0;
};
 
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} // End namespace Arcane
 
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#endif