// -*- C++ -*-

//=============================================================================
/**
 *  @file   Test_and_Set.h
 */
//=============================================================================


#ifndef ACE_TEST_AND_SET_H
#define ACE_TEST_AND_SET_H

#include /**/ "ace/pre.h"
#include "ace/Event_Handler.h"

#if !defined (ACE_LACKS_PRAGMA_ONCE)
# pragma once
#endif /* ACE_LACKS_PRAGMA_ONCE */

ACE_BEGIN_VERSIONED_NAMESPACE_DECL

/**
 * @class ACE_Test_and_Set
 *
 * @brief Implements the classic ``test and set'' operation.
 *
 *     This class keeps track of the status of <is_set_>, which can be
 *     set based on various events (such as receipt of a signal).
 *     This class is derived from ACE_Event_Handler so that it can be
 *     "signaled" by a Reactor when a signal occurs.  We assume that
 *     <TYPE> is a data type that can be assigned the value 0 or 1.
 */
template <class ACE_LOCK, class TYPE>
class ACE_Test_and_Set : public ACE_Event_Handler
{
public:
  ACE_Test_and_Set (TYPE initial_value = 0);

  /// Returns true if we are set, else false.
  TYPE is_set () const;

  /// Sets the <is_set_> status, returning the original value of
  /// <is_set_>.
  TYPE set (TYPE);

  /// Called when object is signaled by OS (either via UNIX signals or
  /// when a Win32 object becomes signaled).
  virtual int handle_signal (int signum,
                             siginfo_t * = 0,
                             ucontext_t * = 0);

private:
  /// Keeps track of our state.
  TYPE is_set_;

  /// Protect the state from race conditions.
  ACE_LOCK lock_;
};

ACE_END_VERSIONED_NAMESPACE_DECL

#if defined (ACE_TEMPLATES_REQUIRE_SOURCE)
#include "ace/Test_and_Set.cpp"
#endif /* ACE_TEMPLATES_REQUIRE_SOURCE */

#if defined (ACE_TEMPLATES_REQUIRE_PRAGMA)
#pragma implementation ("Test_and_Set.cpp")
#endif /* ACE_TEMPLATES_REQUIRE_PRAGMA */

#include /**/ "ace/post.h"
#endif /* ACE_TEST_AND_SET_H */
