text: // -*- C++ -*-
  
  //=============================================================================
  /**
   *  @file    Reactor.h
   *
   *  @author Irfan Pyarali <irfan@cs.wustl.edu>
   *  @author Douglas C. Schmidt <schmidt@cs.wustl.edu>
   */
  //=============================================================================
  
  #ifndef ACE_REACTOR_H
  #define ACE_REACTOR_H
  
  #include /**/ "ace/pre.h"
  
  // Timer Queue is a complicated template class. A simple forward
  // declaration will not work.
  #include "ace/Timer_Queuefwd.h"
  
  #if !defined (ACE_LACKS_PRAGMA_ONCE)
  # pragma once
  #endif /* ACE_LACKS_PRAGMA_ONCE */
  
  // Contains the timer related interface for the Reactor.
  #include "ace/Reactor_Timer_Interface.h"
  
  // Event_Handler.h contains the definition of ACE_Reactor_Mask
  #include "ace/Event_Handler.h"
  
  // Get ACE_Time_Value in
  #include "ace/Time_Value.h"
  
  ACE_BEGIN_VERSIONED_NAMESPACE_DECL
  
  class ACE_Reactor_Impl;
  class ACE_Handle_Set;
  class ACE_Sig_Action;
  class ACE_Sig_Handler;
  class ACE_Sig_Set;
  
  /*
   * Hook to specialize the Reactor implementation with the concrete
   * Reactor type, for example, select, thread pool reactor known
   * at compile time.
   */
  //@@ REACTOR_SPL_INCLUDE_FORWARD_DECL_ADD_HOOK
  
  /**
   * @class ACE_Reactor
   *
   * @brief This class forwards all methods to its delegation/implementation class, e.g.,
   * ACE_Select_Reactor or ACE_WFMO_Reactor.
   */
  class ACE_Export ACE_Reactor : public ACE_Reactor_Timer_Interface
  {
  public:
    /// Operations on the "ready" mask and the "dispatch" mask.
    enum
    {
      /// Retrieve current value of the the "ready" mask or the
      /// "dispatch" mask.
      GET_MASK = 1,
      /// Set value of bits to new mask (changes the entire mask).
      SET_MASK = 2,
      /// Bitwise "or" the value into the mask (only changes enabled
      /// bits).
      ADD_MASK = 3,
      /// Bitwise "and" the negation of the value out of the mask (only
      /// changes enabled bits).
      CLR_MASK = 4
    };
  
    /**
     * You can specify a hook function to event-handling methods that will
     * be called after each iteration of event handling.  If the hook function
     * returns a non-zero value, the event loop will immediately resume
     * waiting for the next event(s) to process without checking the error
     * status of the just-completed iteration of event handling or the
     * end-of-loop indication. If the hook function returns 0, the event
     * handling error status and the end-of-loop indication will be checked
     * as normal, just as if there is no hook function specified.
     */
    typedef int (*REACTOR_EVENT_HOOK)(ACE_Reactor *);
  
    /// Get pointer to a process-wide ACE_Reactor.
    static ACE_Reactor *instance (void);
  
    /**
     * Set pointer to a process-wide ACE_Reactor and return existing
     * pointer.  If @a delete_reactor == true then we'll delete the Reactor
     * at destruction time.
     */
    static ACE_Reactor *instance (ACE_Reactor *, bool delete_reactor = false);
  
    /// Delete the dynamically allocated Singleton
    static void close_singleton (void);
  
    /// Name of the dll in which the dll lives.
    static const ACE_TCHAR *dll_name (void);
  
    /// Name of the component--ACE_Reactor in this case.
    static const ACE_TCHAR *name (void);
  
    // = Singleton reactor event loop management methods.
  
    // Note that these method ONLY work on the "Singleton Reactor,"
    // i.e., the one returned from ACE_Reactor::instance().
    /**
     * Run the event loop until the
     * ACE_Reactor::handle_events()/ACE_Reactor::alertable_handle_events()
     * method returns -1 or the end_event_loop() method is invoked.
     * Note that this method can only be used by the singleton
     * ACE_Reactor::instance().  Thus, to run another reactor use
     * ACE_Reactor::run_reactor_event_loop().
     *
     * @deprecated Use ACE_Reactor::instance()->run_reactor_event_loop() instead
     */
    static int run_event_loop (void);
    static int run_alertable_event_loop (void);
  
    /**
     * Run the event loop until the ACE_Reactor::handle_events() or
     * <ACE_Reactor::alertable_handle_events> methods returns -1, the
     * end_event_loop() method is invoked, or the ACE_Time_Value
     * expires.  Note that this method can only be used by the singleton
     * ACE_Reactor::instance().  Thus, to run another reactor use
     * <ACE_Reactor::run_reactor_event_loop>.
     *
     * @deprecated Use ACE_Reactor::instance()->run_reactor_event_loop() instead
     */
    static int run_event_loop (ACE_Time_Value &tv);
    static int run_alertable_event_loop (ACE_Time_Value &tv);
  
    /**
     * Instruct the ACE_Reactor::instance() to terminate its event loop
     * and notifies the ACE_Reactor::instance() so that it can wake up
     * and close down gracefully.  Note that this method can only be
     * used by the singleton ACE_Reactor::instance().  Thus, to
     * terminate another reactor, use
     * <ACE_Reactor::end_reactor_event_loop>.
     *
     * @deprecated Use ACE_Reactor::instance()->end_reactor_event_loop() instead
     */
    static int end_event_loop (void);
  
    /**
     * Report if the ACE_Reactor::instance()'s event loop is finished.
     * Note that this method can only be used by the singleton
     * ACE_Reactor::instance().  Thus, to check another reactor use
     * <ACE_Reactor::reactor_event_loop_done>.
     *
     * @deprecated Use ACE_Reactor::instance()->reactor_event_loop_done() instead
     */
    static int event_loop_done (void);
  
    /**
     * Resets the ACE_Reactor::end_event_loop_  static so that the
     * run_event_loop() method can be restarted.  Note that this method
     * can only be used by the singleton ACE_Reactor::instance().  Thus,
     * to reset another reactor use ACE_Reactor::reset_reactor_event_loop().
     *
     * @deprecated Use ACE_Reactor::instance()->reset_reactor_event_loop()
     * instead
     */
    static void reset_event_loop (void);
  
    /**
     * The singleton reactor is used by the ACE_Service_Config.
     * Therefore, we must check for the reconfiguration request and
     * handle it after handling an event.
     */
    static int check_reconfiguration (ACE_Reactor *);
  
    // = Reactor event loop management methods.
  
    // These methods work with an instance of a reactor.
    /**
     * Run the event loop until the ACE_Reactor::handle_events() or
     * ACE_Reactor::alertable_handle_events() method returns -1 or
     * the end_reactor_event_loop() method is invoked.
     */
    int run_reactor_event_loop (REACTOR_EVENT_HOOK = 0);
    int run_alertable_reactor_event_loop (REACTOR_EVENT_HOOK = 0);
  
    /**
     * Run the event loop until the ACE_Reactor::handle_events() or
     * ACE_Reactor::alertable_handle_events() method returns -1, the
     * end_reactor_event_loop() method is invoked, or the ACE_Time_Value
     * expires while the underlying event demultiplexer is waiting for
     * events.
     * Note that it is possible for events to continuously be available,
     * avoiding the need to wait for events. In this situation the timeout
     * value will not have an opportunity to expire until the next time
     * the underlying event demultiplexer waits for events.
     */
    int run_reactor_event_loop (ACE_Time_Value &tv,
                                REACTOR_EVENT_HOOK = 0);
    int run_alertable_reactor_event_loop (ACE_Time_Value &tv,
                                          REACTOR_EVENT_HOOK = 0);
  
    /**
     * Instruct the Reactor to terminate its event loop and notifies the
     * Reactor so that it can wake up and deactivate
     * itself. Deactivating the Reactor would allow the Reactor to be
     * shutdown gracefully. Internally the Reactor calls deactivate ()
     * on the underlying implementation.
     * Any queued notifications remain queued on return from this method.
     * If the event loop is restarted in the future, the notifications
     * will be dispatched then. If the reactor is closed or deleted without
     * further dispatching, the notifications will be lost.
     */
    int end_reactor_event_loop (void);
  
    /// Indicate if the Reactor's event loop has been ended.
    int reactor_event_loop_done (void);
  
    /// Resets the ACE_Reactor::end_event_loop_ static so that the
    /// run_event_loop() method can be restarted.
    void reset_reactor_event_loop (void);
  
    /**
     * Create the Reactor using @a implementation.  The flag
     * @a delete_implementation tells the Reactor whether or not to
     * delete the @a implementation on destruction.
     */
    ACE_Reactor (ACE_Reactor_Impl *implementation = 0,
                 bool delete_implementation = false);
  
    /// Close down and release all resources.
    /**
     * Any notifications that remain queued on this reactor instance are
     * lost.
     */
    virtual ~ACE_Reactor (void);
  
    /**
     * Initialize the ACE_Reactor to manage @a max_number_of_handles.
     * If @a restart is false then the ACE_Reactor's handle_events()
     * method will be restarted automatically when @c EINTR occurs.  If
     * @a signal_handler or @a timer_queue are non-0 they are used as the
     * signal handler and timer queue, respectively.
     */
    int open (size_t max_number_of_handles,
              bool restart = false,
              ACE_Sig_Handler *signal_handler = 0,
              ACE_Timer_Queue *timer_queue = 0);
  
    /// Use a user specified signal handler instead.
    int set_sig_handler (ACE_Sig_Handler *signal_handler);
  
    /// Set a user-specified timer queue.
    int timer_queue (ACE_Timer_Queue *tq);
  
    /// Return the current ACE_Timer_Queue.
    ACE_Timer_Queue *timer_queue (void) const;
  
    /// Close down and release all resources.
    int close (void);
  
    // = Event loop drivers.
  
    /**
     * Returns non-zero if there are I/O events "ready" for dispatching,
     * but does not actually dispatch the event handlers.  By default,
     * don't block while checking this, i.e., "poll".
     */
    int work_pending (const ACE_Time_Value &max_wait_time = ACE_Time_Value::zero);
  
    /**
     * This event loop driver blocks for up to @a max_wait_time before
     * returning.  It will return earlier if events occur.  Note that
     * @a max_wait_time can be 0, in which case this method blocks
     * indefinitely until events occur.
     *
     * @a max_wait_time is decremented to reflect how much time this call
     * took.  For instance, if a time value of 3 seconds is passed to
     * handle_events and an event occurs after 2 seconds,
     * @a max_wait_time will equal 1 second.  This can be used if an
     * application wishes to handle events for some fixed amount of
     * time.
     *
     * Returns the total number of timers and I/O ACE_Event_Handlers
     * that were dispatched, 0 if the @a max_wait_time elapsed without
     * dispatching any handlers, or -1 if an error occurs.
     *
     * The only difference between alertable_handle_events() and
     * handle_events() is that in the alertable case, the eventloop will
     * return when the system queues an I/O completion routine or an
     * Asynchronous Procedure Call.
     */
    int handle_events (ACE_Time_Value *max_wait_time = 0);
    int alertable_handle_events (ACE_Time_Value *max_wait_time = 0);
  
    /**
     * This method is just like the one above, except the
     * @a max_wait_time value is a reference and can therefore never be
     * NULL.
     *
     * The only difference between alertable_handle_events() and
     * handle_events() is that in the alertable case, the eventloop will
     * return when the system queues an I/O completion routine or an
     * Asynchronous Procedure Call.
     */
    int handle_events (ACE_Time_Value &max_wait_time);
    int alertable_handle_events (ACE_Time_Value &max_wait_time);
  
    // = Register and remove handlers.
  
    /**
     * Register handler for I/O events.
     *
     * A handler can be associated with multiple handles. A handle
     * cannot be associated with multiple handlers.
     *
     * The handle will come from ACE_Event_Handler::get_handle().
     *
     * Reactor will call ACE_Event_Handler::add_reference() for a new
     * handler/handle pair.
     *
     * If this handler/handle pair has already been registered, any new
     * masks specified will be added. In this case,
     * ACE_Event_Handler::add_reference() will not be called.
     *
     * If the registered handler is currently suspended, it will remain
     * suspended.  When the handler is resumed, it will have the
     * existing masks plus any masks added through this call. Handlers
     * do not have partial suspensions.
     */
    int register_handler (ACE_Event_Handler *event_handler,
                          ACE_Reactor_Mask mask);
  
    /**
     * Register handler for I/O events.
     *
     * Same as register_handler(ACE_Event_Handler*,ACE_Reactor_Mask),
     * except handle is explicitly specified.
     */
    int register_handler (ACE_HANDLE io_handle,
                          ACE_Event_Handler *event_handler,
                          ACE_Reactor_Mask mask);
  
  #if defined (ACE_WIN32)
  
    /**
     * Register handler for OS events.
     *
     * Register an @a event_handler that will be notified when
     * <event_handle> is signaled.  This will call back its
     * <handle_signal> hook method.
     *
     * Reactor will call ACE_Event_Handler::add_reference() for a new
     * handler/handle pair.
     *
     * This interface is only available Win32 platforms because
     * ACE_HANDLE is an int on non-Win32 platforms and compilers are not
     * able to tell the difference between
     * register_handler(ACE_Event_Handler*,ACE_Reactor_Mask) and
     * register_handler(ACE_Event_Handler*,ACE_HANDLE).
     */
    int register_handler (ACE_Event_Handler *event_handler,
                          ACE_HANDLE event_handle = ACE_INVALID_HANDLE);
  
  #endif /* ACE_WIN32 */
  
    /**
     * Register handler for I/O events.
     *
     * Similar to
     * register_handler(ACE_HANDLE,ACE_Event_Handler*,ACE_Reactor_Mask),
     * except that the user gets to specify the event handle that will
     * be used for this registration.  This only applies to Reactors
     * that use event handles for I/O registrations.
     */
    int register_handler (ACE_HANDLE event_handle,
                          ACE_HANDLE io_handle,
                          ACE_Event_Handler *event_handler,
                          ACE_Reactor_Mask mask);
  
    /**
     * Register handler for multiple I/O events.
     *
     * Shorthand for calling
     * register_handler(ACE_HANDLE,ACE_Event_Handler*,ACE_Reactor_Mask),
     * multiple times for the same @a event_handler and @a masks but
     * different @a handles.
     */
    int register_handler (const ACE_Handle_Set &handles,
                          ACE_Event_Handler *event_handler,
                          ACE_Reactor_Mask masks);
  
    /**
     * Register handler for signals.
     *
     * Register @a new_sh to handle the signal @a signum using the
     * @a new_disp.  Returns the @a old_sh that was previously registered
     * (if any), along with the @a old_disp of the signal handler.
     *
     * Reactor will call ACE_Event_Handler::add_reference() on @a new_sh
     * and ACE_Event_Handler::remove_reference() on @a old_sh.
     */
    int register_handler (int signum,
                          ACE_Event_Handler *new_sh,
                          ACE_Sig_Action *new_disp = 0,
                          ACE_Event_Handler **old_sh = 0,
                          ACE_Sig_Action *old_disp = 0);
  
    /**
     * Register handler for multiple signals.
     *
     * Shorthand for calling
     * register_handler(int,ACE_Event_Handler*,ACE_Sig_Action*,ACE_Event_Handler**,ACE_Sig_Action*)
     * multiple times for the same @a event_handler and @a sig_action but
     * different <signals>.
     */
    int register_handler (const ACE_Sig_Set &sigset,
                          ACE_Event_Handler *event_handler,
                          ACE_Sig_Action *sig_action = 0);
  
    /**
     * Remove @a masks from @a handle registration.
     *
     * For I/O handles, @a masks are removed from the Reactor.  Unless
     * @a masks includes ACE_Event_Handler::DONT_CALL,
     * ACE_Event_Handler::handle_close() will be called with the @a masks
     * that have been removed.  If all masks have been removed,
     * ACE_Event_Handler::remove_reference() will be called.
     *
     * For OS handles, the @a handle is removed from the Reactor.  Unless
     * @a masks includes ACE_Event_Handler::DONT_CALL,
     * ACE_Event_Handler::handle_close() will be called with
     * ACE_Event_Handler::NULL_MASK.
     * ACE_Event_Handler::remove_reference() will also be called.
     */
    int remove_handler (ACE_HANDLE handle,
                        ACE_Reactor_Mask masks);
  
    /**
     * Remove @a masks from @a event_handler registration.
     *
     * Same as remove_handler(ACE_HANDLE,ACE_Reactor_Mask), except
     * @a handle comes from ACE_Event_Handler::get_handle().
     */
    int remove_handler (ACE_Event_Handler *event_handler,
                        ACE_Reactor_Mask masks);
  
    /**
     * Remove @a masks from multiple <handle> registrations.
     *
     * Shorthand for calling remove_handler(ACE_HANDLE,ACE_Reactor_Mask)
     * multiple times for the same @a masks but different @a handles.
     */
    int remove_handler (const ACE_Handle_Set &handles,
                        ACE_Reactor_Mask masks);
  
    /**
     * Remove signal handler registration.
     *
     * Remove the ACE_Event_Handler currently associated with @a signum.
     * Install the new disposition (if given) and return the previous
     * disposition (if desired by the caller).
     *
     * Note that the registered handler's ACE_Event_Handler::handle_close ()
     * callback will be called to indicate the signal handler has been removed.
     * Unlike with I/O handles, there is no way to prevent this callback. The
     * handle_close() callback can check the passed mask for the value
     * ACE_Event_Handler::SIGNAL_MASK to tell when the callback is the result
     * of a signal handler removal.
     */
    int remove_handler (int signum,
                        ACE_Sig_Action *new_disp,
                        ACE_Sig_Action *old_disp = 0,
                        int sigkey = -1);
  
    /**
     * Remove multiple signal handler registrations.
     *
     * Shorthand for calling
     * remove_handler(int,ACE_Sig_Action*,ACE_Sig_Action*,int) multiple
     * times for every signal in @a sigset.
     */
    int remove_handler (const ACE_Sig_Set &sigset);
  
    // = Suspend and resume Handlers.
  
    /**
     * Suspend @a handle temporarily.
     */
    int suspend_handler (ACE_HANDLE handle);
  
    /**
     * Suspend @a event_handler temporarily.
     *
     * Handle is obtained from ACE_Event_Handler::get_handle().
     */
    int suspend_handler (ACE_Event_Handler *event_handler);
  
    /**
     * Suspend @a handles temporarily.
     *
     * Shorthand for calling suspend_handler(ACE_HANDLE) with multiple
     * @a handles.
     */
    int suspend_handler (const ACE_Handle_Set &handles);
  
    /**
     * Suspend all registered handles temporarily.
     */
    int suspend_handlers (void);
  
    /**
     * Resume @a handle.
     */
    int resume_handler (ACE_HANDLE handle);
  
    /**
     * Resume @a event_handler.
     *
     * Handle is obtained from ACE_Event_Handler::get_handle().
     */
    int resume_handler (ACE_Event_Handler *event_handler);
  
    /**
     * Resume @a handles.
     *
     * Shorthand for calling resume_handler(ACE_HANDLE) with multiple
     * @a handles.
     */
    int resume_handler (const ACE_Handle_Set &handles);
  
    /**
     * Resume all registered handles.
     */
    int resume_handlers (void);
  
    /// Does the reactor allow the application to resume the handle on
    /// its own ie. can it pass on the control of handle resumption to
    /// the application. A positive value indicates that the handlers
    /// are application resumable. A value of 0 indicates otherwise.
    int resumable_handler (void);
  
    // = Timer management.
  
    /**
     * Schedule a timer event.
     *
     * Schedule a timer event that will expire after an @a delay amount
     * of time.  The return value of this method, a timer_id value,
     * uniquely identifies the @a event_handler in the ACE_Reactor's
     * internal list of timers.  This timer_id value can be used to
     * cancel the timer with the cancel_timer() call.
     *
     * Reactor will call ACE_Event_Handler::add_reference() on the
     * handler.  After the timeout occurs and
     * ACE_Event_Handler::handle_timeout() has completed, the handler
     * will be implicitly removed from the Reactor and
     * ACE_Event_Handler::remove_reference() will be called.
     *
     * @see cancel_timer()
     * @see reset_timer_interval()
     *
     * @param event_handler Event handler to schedule on reactor. The handler's
     *                      handle_timeout() method will be called when this
     *                      scheduled timer expires.
     * @param arg           Argument passed to the handle_timeout() method of
     *                      event_handler.
     * @param delay         Time interval after which the timer will expire.
     * @param interval      Time interval for which the timer will be
     *                      automatically rescheduled if the handle_timeout()
     *                      callback does not return a value less than 0.
     *
     * @retval              timer id, on success. The id can be used to
     *                      cancel or reschedule this timer.
     * @retval              -1 on failure, with errno set.
     */
    virtual long schedule_timer (ACE_Event_Handler *event_handler,
                                 const void *arg,
                                 const ACE_Time_Value &delay,
                                 const ACE_Time_Value &interval =
                                  ACE_Time_Value::zero);
  #if defined (ACE_HAS_CPP11)
    template<class Rep1, class Period1, class Rep2 = int, class Period2 = std::ratio<1>>
    long schedule_timer (ACE_Event_Handler *event_handler,
                         const void *arg,
                         const std::chrono::duration<Rep1, Period1>& delay,
                         const std::chrono::duration<Rep2, Period2>& interval =
                          std::chrono::duration<Rep2, Period2>::zero ())
    {
      ACE_Time_Value const tv_delay (delay);
      ACE_Time_Value const tv_interval (interval);
      return this->schedule_timer (event_handler, arg, tv_delay, tv_interval);
    }
  #endif
    /**
     * Reset recurring timer interval.
     *
     * Resets the interval of the timer represented by @a timer_id to
     * @a interval, which is specified in relative time to the current
     * gettimeofday().  If @a interval is equal to
     * ACE_Time_Value::zero, the timer will become a non-rescheduling
     * timer.  Returns 0 if successful, -1 if not.
     *
     * This change will not take effect until the next timeout.
     */
    virtual int reset_timer_interval (long timer_id,
                                      const ACE_Time_Value &interval);
  #if defined (ACE_HAS_CPP11)
    template<class Rep, class Period>
    int reset_timer_interval (long timer_id,
                              const std::chrono::duration<Rep, Period>& interval)
    {
      ACE_Time_Value const tv_interval (interval);
      return this->reset_timer_interval (timer_id, tv_interval);
    }
  #endif
  
    /**
     * Cancel timer.
     *
     * Cancel timer associated with @a timer_id that was returned from
     * the schedule_timer() method.  If arg is non-NULL then it will be
     * set to point to the ``magic cookie'' argument passed in when the
     * handler was registered.  This makes it possible to free up the
     * memory and avoid memory leaks.  Returns 1 if cancellation
     * succeeded and 0 if the @a timer_id wasn't found.
     *
     * On successful cancellation, ACE_Event_Handler::handle_close()
     * will be called with ACE_Event_Handler::TIMER_MASK.
     * ACE_Event_Handler::remove_reference() will also be called.
     */
    virtual int cancel_timer (long timer_id,
                              const void **arg = 0,
                              int dont_call_handle_close = 1);
  
    /**
     * Cancel all timers associated with event handler.
     *
     * Shorthand for calling cancel_timer(long,const void **,int)
     * multiple times for all timer associated with @a event_handler.
     *
     * ACE_Event_Handler::handle_close() will be called with
     * ACE_Event_Handler::TIMER_MASK only once irrespective of the
     * number of timers associated with the event handler.
     * ACE_Event_Handler::remove_reference() will also be called once
     * for every timer associated with the event handler.
     *
     * In case this operation is called with a nil event_handler
     * it returns with 0 as the number of handlers cancelled.
     *
     * Returns number of handlers cancelled.
     */
    virtual int cancel_timer (ACE_Event_Handler *event_handler,
                              int dont_call_handle_close = 1);
  
    // = High-level Event_Handler scheduling operations
  
    /// Add @a masks_to_be_added to the @a event_handler's entry.
    /// @a event_handler must already have been registered.
    /// Note that this call does not cause the Reactor to re-examine
    /// its set of handlers - the new masks will be noticed the next
    /// time the Reactor waits for activity. If there is no other
    /// activity expected, or you need immediate re-examination of the
    /// wait masks, either call ACE_Reactor::notify after this call, or
    /// use ACE_Reactor::register_handler instead.
    int schedule_wakeup (ACE_Event_Handler *event_handler,
                         ACE_Reactor_Mask masks_to_be_added);
  
    /// Add @a masks_to_be_added to the @a handle's entry.  <event_handler>
    /// associated with @a handle must already have been registered.
    /// Note that this call does not cause the Reactor to re-examine
    /// its set of handlers - the new masks will be noticed the next
    /// time the Reactor waits for activity. If there is no other
    /// activity expected, or you need immediate re-examination of
    /// the wait masks, either call ACE_Reactor::notify after this call,
    /// or use ACE_Reactor::register_handler instead.
    int schedule_wakeup (ACE_HANDLE handle,
                         ACE_Reactor_Mask masks_to_be_added);
  
    /// Clear @a masks_to_be_cleared from the @a event_handler's entry.
    /// Note that this call does not cause the Reactor to re-examine
    /// its set of handlers - the new masks will be noticed the next
    /// time the Reactor waits for activity. If there is no other
    /// activity expected, or you need immediate re-examination of
    /// the wait masks, either call ACE_Reactor::notify after this
    /// call, or use ACE_Reactor::register_handler instead.
    int cancel_wakeup (ACE_Event_Handler *event_handler,
                       ACE_Reactor_Mask masks_to_be_cleared);
  
    /// Clear @a masks_to_be_cleared from the @a handle's entry.
    /// Note that this call does not cause the Reactor to re-examine
    /// its set of handlers - the new masks will be noticed the next
    /// time the Reactor waits for activity. If there is no other
    /// activity expected, or you need immediate re-examination of
    /// the wait masks, either call ACE_Reactor::notify after this
    /// call, or use ACE_Reactor::register_handler instead.
    int cancel_wakeup (ACE_HANDLE handle,
                       ACE_Reactor_Mask masks_to_be_cleared);
  
    // = Notification methods.
  
    /**
     * Dispatch user specified events.
     *
     * Handler will be dispatched irrespective of whether it is
     * registered, not registered, or suspended in the Reactor.
     *
     * If user specified event is successfully queued,
     * ACE_Event_Handler::add_reference() will be called.  After the
     * notify occurs and the upcall to the handler completes, the
     * handler will be implicitly removed from the Reactor and
     * ACE_Event_Handler::remove_reference() will be called.  No other
     * upcall reference counting is done.
     *
     * For I/O or OS events, the upcall is invoked with an
     * ACE_INVALID_HANDLE.
     *
     * For timer events, the upcall is invoked with a null ACT.
     *
     * @param event_handler: IN - Handler on which the event will be
     * dispatched.
     * @param masks: IN - Events to be dispatched - multiple events can
     * be OR'd together.
     * @param timeout: INOUT - Relative time up to which to wait for
     * user specified event to be queued.  If tv is 0, wait
     * indefinitely.  When the call returns, tv has the time remaining
     * after the call completes.
     */
    int notify (ACE_Event_Handler *event_handler = 0,
                ACE_Reactor_Mask masks = ACE_Event_Handler::EXCEPT_MASK,
                ACE_Time_Value *timeout = 0);
  
    /**
     * Set the maximum number of times that ACE_Reactor will
     * iterate and dispatch the ACE_Event_Handlers that are passed in
     * via the notify queue before breaking out of its
     * ACE_Message_Queue::dequeue() loop.  By default, this is set to
     * -1, which means "iterate until the queue is empty."  Setting this
     * to a value like "1 or 2" will increase "fairness" (and thus
     * prevent starvation) at the expense of slightly higher dispatching
     * overhead.
     */
    void max_notify_iterations (int iterations);
  
    /**
     * Get the maximum number of times that the ACE_Reactor will
     * iterate and dispatch the ACE_Event_Handler's that are passed in
     * via the notify queue before breaking out of its
     * ACE_Message_Queue::dequeue() loop.
     */
    int max_notify_iterations (void);
  
    /**
     * Purge any notifications pending in this reactor for the specified
     * ACE_Event_Handler object. If @a eh == 0, all notifications for
     * all handlers are removed (but not any notifications posted just
     * to wake up the reactor itself). Returns the number of
     * notifications purged.  Returns -1 on error.
     *
     * After the purging occurs, the handler will be implicitly removed
     * from the Reactor and ACE_Event_Handler::remove_reference() will
     * be called.
     */
    int purge_pending_notifications (ACE_Event_Handler *eh,
                                     ACE_Reactor_Mask =
                                              ACE_Event_Handler::ALL_EVENTS_MASK);
  
    // = Assorted helper methods.
  
    /**
     * Return the Event_Handler associated with @a handle.  Return 0 if
     * @a handle is not registered.
     *
     * Reactor will call ACE_Event_Handler::add_reference() on the
     * handler before returning it.
     */
    ACE_Event_Handler *find_handler (ACE_HANDLE handle);
  
    /**
     * Check to see if @a handle is associated with a valid Event_Handler
     * bound to @a mask.  Return the @c event_handler associated with this
     * @a handler if @a event_handler != 0.
     *
     * Reactor will call ACE_Event_Handler::add_reference() on the
     * handler before returning it if @a event_handler != 0.
     */
    int handler (ACE_HANDLE handle,
                 ACE_Reactor_Mask mask,
                 ACE_Event_Handler **event_handler = 0);
  
    /**
     * Check to see if @a signum is associated with a valid Event_Handler
     * bound to a signal.  Return the @a event_handler associated with
     * this @c handler if @a event_handler != 0.
     */
    int handler (int signum,
                 ACE_Event_Handler **event_handler = 0);
  
    /// Returns true if Reactor has been successfully initialized, else
    /// false.
    int initialized (void);
  
    /// Returns the current size of the Reactor's internal descriptor
    /// table.
    size_t size (void) const;
  
    /// Returns a reference to the Reactor's internal lock.
    ACE_Lock &lock (void);
  
    /// Wake up all threads in waiting in the event loop
    void wakeup_all_threads (void);
  
    /// Transfers ownership of Reactor to the @a new_owner.
    int owner (ACE_thread_t new_owner,
               ACE_thread_t *old_owner = 0);
  
    /// Return the ID of the "owner" thread.
    int owner (ACE_thread_t *owner);
  
    /// Set position of the owner thread.
    void requeue_position (int position);
  
    /// Get position of the owner thread.
    int requeue_position (void);
  
    /// Get the existing restart value.
    bool restart (void);
  
    /// Set a new value for restart and return the original value.
    bool restart (bool r);
  
    // = Low-level wait_set mask manipulation methods.
  
    /// GET/SET/ADD/CLR the dispatch mask "bit" bound with the
    /// @a event_handler and @a mask.
    int mask_ops (ACE_Event_Handler *event_handler,
                  ACE_Reactor_Mask mask,
                  int ops);
  
    /// GET/SET/ADD/CLR the dispatch MASK "bit" bound with the @a handle
    /// and @a mask.
    int mask_ops (ACE_HANDLE handle,
                  ACE_Reactor_Mask mask,
                  int ops);
  
    // = Low-level ready_set mask manipulation methods.
    /// GET/SET/ADD/CLR the ready "bit" bound with the @a event_handler
    /// and @a mask.
    int ready_ops (ACE_Event_Handler *event_handler,
                   ACE_Reactor_Mask mask,
                   int ops);
  
    /// GET/SET/ADD/CLR the ready "bit" bound with the @a handle and @a mask.
    int ready_ops (ACE_HANDLE handle,
                   ACE_Reactor_Mask mask,
                   int ops);
  
    /// Get the implementation class
    ACE_Reactor_Impl *implementation (void) const;
  
    /**
     * Returns 0, if the size of the current message has been put in
     * @a size returns -1, if not.  ACE_HANDLE allows the reactor to
     * check if the caller is valid.  Used for CLASSIX Reactor
     * implementation.
     */
    int current_info (ACE_HANDLE handle, size_t &msg_size);
  
    /// Return true if we any event associations were made by the reactor
    /// for the handles that it waits on, false otherwise.
    bool uses_event_associations (void);
  
    /// Declare the dynamic allocation hooks.
    ACE_ALLOC_HOOK_DECLARE;
  
    /// Dump the state of the object.
    void dump (void) const;
  
  protected:
    /// Set the implementation class.
    void implementation (ACE_Reactor_Impl *implementation);
  
    /// Delegation/implementation class that all methods will be
    /// forwarded to.
    ACE_Reactor_Impl *implementation_;
  
    /// Flag used to indicate whether we are responsible for cleaning up
    /// the implementation instance
    bool delete_implementation_;
  
    /// Pointer to a process-wide ACE_Reactor singleton.
    static ACE_Reactor *reactor_;
  
    /// Must delete the reactor_ singleton if true.
    static bool delete_reactor_;
  
    /// Deny access since member-wise won't work...
    ACE_Reactor (const ACE_Reactor &);
    ACE_Reactor &operator = (const ACE_Reactor &);
  };
  
  ACE_END_VERSIONED_NAMESPACE_DECL
  
  
  #if defined (__ACE_INLINE__)
  #include "ace/Reactor.inl"
  #endif /* __ACE_INLINE__ */
  
  #include /**/ "ace/post.h"
  
  #endif /* ACE_REACTOR_H */
  