text: // -*- C++ -*-
  
  //=============================================================================
  /**
   *  @file    Reactor_Impl.h
   *
   *  @author Irfan Pyarali
   */
  //=============================================================================
  
  
  #ifndef ACE_REACTOR_IMPL_H
  #define ACE_REACTOR_IMPL_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 */
  
  // Event_Handler.h contains the definition of ACE_Reactor_Mask
  #include "ace/Event_Handler.h"
  #include "ace/Countdown_Time.h"
  
  ACE_BEGIN_VERSIONED_NAMESPACE_DECL
  
  // Forward decls
  class ACE_Handle_Set;
  class ACE_Reactor_Impl;
  class ACE_Sig_Action;
  class ACE_Sig_Handler;
  class ACE_Sig_Set;
  
  /**
   * @class ACE_Reactor_Notify
   *
   * @internal This class is for ACE internal use only.
   *
   * @brief Abstract class for unblocking an ACE_Reactor_Impl from its
   * event loop.
   */
  class ACE_Export ACE_Reactor_Notify : public ACE_Event_Handler
  {
  public:
    // = Initialization and termination methods.
    virtual int open (ACE_Reactor_Impl *,
                      ACE_Timer_Queue *timer_queue = 0,
                      int disable_notify = 0) = 0;
    virtual int close (void) = 0;
  
    /**
     * Called by a thread when it wants to unblock the <Reactor_Impl>.
     * This wakeups the <Reactor_Impl> if currently blocked.  Pass over
     * both the <Event_Handler> *and* the @a mask to allow the caller to
     * dictate which <Event_Handler> method the <Reactor_Impl> will
     * invoke.  The ACE_Time_Value indicates how long to blocking
     * trying to notify the <Reactor_Impl>.  If @a timeout == 0, the
     * caller will block until action is possible, else will wait until
     * the relative time specified in *@a timeout elapses).
     */
    virtual int notify (ACE_Event_Handler *eh = 0,
                        ACE_Reactor_Mask mask = ACE_Event_Handler::EXCEPT_MASK,
                        ACE_Time_Value *timeout = 0) = 0;
  
    /// Handles pending threads (if any) that are waiting to unblock the
    /// <Reactor_Impl>.
    virtual int dispatch_notifications (int &number_of_active_handles,
                                        ACE_Handle_Set &rd_mask) = 0;
  
    /// Returns the ACE_HANDLE of the notify pipe on which the reactor
    /// is listening for notifications so that other threads can unblock
    /// the <Reactor_Impl>
    virtual ACE_HANDLE notify_handle (void) = 0;
  
    /// Verify whether the buffer has dispatchable info  or not.
    virtual int is_dispatchable (ACE_Notification_Buffer &buffer)= 0;
  
    /// Handle one of the notify call on the <handle>. This could be
    /// because of a thread trying to unblock the <Reactor_Impl>
    virtual int dispatch_notify (ACE_Notification_Buffer &buffer) = 0;
  
    /// Read one of the notify call on the @a handle into the
    /// @a buffer. This could be because of a thread trying to unblock
    /// the <Reactor_Impl>
    virtual int read_notify_pipe (ACE_HANDLE handle,
                                  ACE_Notification_Buffer &buffer) = 0;
    /**
     * Set the maximum number of times that the <handle_input> method
     * will iterate and dispatch the ACE_Event_Handlers that are
     * passed in via the notify queue before breaking out of the event
     * 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.
     */
    virtual void max_notify_iterations (int) = 0;
  
    /**
     * Get the maximum number of times that the <handle_input> method
     * will iterate and dispatch the ACE_Event_Handlers that are
     * passed in via the notify queue before breaking out of its event
     * loop.
     */
    virtual int max_notify_iterations (void) = 0;
  
    /**
     * Purge any notifications pending in this reactor for the specified
     * ACE_Event_Handler object. Returns the number of notifications
     * purged. Returns -1 on error.
     */
    virtual int purge_pending_notifications (ACE_Event_Handler * = 0,
                                             ACE_Reactor_Mask    = ACE_Event_Handler::ALL_EVENTS_MASK) = 0;
  
    /// Dump the state of an object.
    virtual void dump (void) const = 0;
  };
  
  /**
   * @class ACE_Reactor_Impl
   *
   * @brief An abstract class for implementing the Reactor Pattern.
   */
  class ACE_Export ACE_Reactor_Impl
  {
  public:
    /// Close down and release all resources.
    virtual ~ACE_Reactor_Impl (void);
  
    /// Initialization.
    virtual int open (size_t size,
                      bool restart = false,
                      ACE_Sig_Handler * = 0,
                      ACE_Timer_Queue * = 0,
                      int disable_notify_pipe = 0,
                      ACE_Reactor_Notify * = 0) = 0;
  
    /**
     * 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.
     */
    virtual int current_info (ACE_HANDLE, size_t & /* size */) = 0;
  
    /// Use a user specified signal handler instead.
    virtual int set_sig_handler (ACE_Sig_Handler *signal_handler) = 0;
  
    /// Set a user-specified timer queue.
    virtual int timer_queue (ACE_Timer_Queue *tq) = 0;
  
    /// Return the current ACE_Timer_Queue.
    virtual ACE_Timer_Queue *timer_queue (void) const = 0;
  
    /// Close down and release all resources.
    virtual int close (void) = 0;
  
    // = 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".
     */
    virtual int work_pending (const ACE_Time_Value &max_wait_time =  ACE_Time_Value::zero)  = 0;
  
    /**
     * 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 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.
     */
    virtual int handle_events (ACE_Time_Value *max_wait_time = 0) = 0;
    virtual int alertable_handle_events (ACE_Time_Value *max_wait_time = 0) = 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.
     */
    virtual int handle_events (ACE_Time_Value &max_wait_time) = 0;
    virtual int alertable_handle_events (ACE_Time_Value &max_wait_time) = 0;
  
    // = Event handling control.
  
    /**
     * Return the status of Reactor.  If this function returns 0, the reactor is
     * actively handling events.  If it returns non-zero, <handling_events> and
     * <handle_alertable_events> return -1 immediately.
     */
    virtual int deactivated (void) = 0;
  
    /**
     * Control whether the Reactor will handle any more incoming events or not.
     * If @a do_stop == 1, the Reactor will be disabled.  By default, a reactor
     * is in active state and can be deactivated/reactived as wish.
     */
    virtual void deactivate (int do_stop) = 0;
  
    // = Register and remove Handlers.
  
    /// Register @a event_handler with @a mask.  The I/O handle will always
    /// come from <get_handle> on the @a event_handler.
    virtual int register_handler (ACE_Event_Handler *event_handler,
                                  ACE_Reactor_Mask mask) = 0;
  
    /// Register @a event_handler with @a mask.  The I/O handle is provided
    /// through the <io_handle> parameter.
    virtual int register_handler (ACE_HANDLE io_handle,
                                  ACE_Event_Handler *event_handler,
                                  ACE_Reactor_Mask mask) = 0;
  
  #if defined (ACE_WIN32)
  
    // Originally this interface was available for all platforms, but
    // because ACE_HANDLE is an int on non-Win32 platforms, 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). Therefore, we
    // have restricted this method to Win32 only.
  
    /**
     * Register an @a event_handler that will be notified when
     * <event_handle> is signaled.  Since no event mask is passed
     * through this interface, it is assumed that the <event_handle>
     * being passed in is an event handle and not an I/O handle.
     */
    virtual int register_handler (ACE_Event_Handler *event_handler,
                                  ACE_HANDLE event_handle = ACE_INVALID_HANDLE) = 0;
  
  #endif /* ACE_WIN32 */
  
    /**
     * Register an @a event_handler that will be notified when
     * <event_handle> is signaled.  @a mask specifies the network events
     * that the @a event_handler is interested in.
     */
    virtual int register_handler (ACE_HANDLE event_handle,
                                  ACE_HANDLE io_handle,
                                  ACE_Event_Handler *event_handler,
                                  ACE_Reactor_Mask mask) = 0;
  
    /// Register @a event_handler with all the @a handles in the <Handle_Set>.
    virtual int register_handler (const ACE_Handle_Set &handles,
                                  ACE_Event_Handler *event_handler,
                                  ACE_Reactor_Mask mask) = 0;
  
    /**
     * 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.
     */
    virtual 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) = 0;
  
    /// Registers @a new_sh to handle a set of signals @a sigset using the
    /// @a new_disp.
    virtual int register_handler (const ACE_Sig_Set &sigset,
                                  ACE_Event_Handler *new_sh,
                                  ACE_Sig_Action *new_disp = 0) = 0;
  
    /**
     * Removes @a event_handler.  Note that the I/O handle will be
     * obtained using <get_handle> method of @a event_handler .  If
     * @a mask == ACE_Event_Handler::DONT_CALL then the <handle_close>
     * method of the @a event_handler is not invoked.
     */
    virtual int remove_handler (ACE_Event_Handler *event_handler,
                                ACE_Reactor_Mask mask) = 0;
  
    /**
     * Removes @a handle.  If @a mask == ACE_Event_Handler::DONT_CALL
     * then the <handle_close> method of the associated <event_handler>
     * is not invoked.
     */
    virtual int remove_handler (ACE_HANDLE handle,
                                ACE_Reactor_Mask mask) = 0;
  
    /**
     * Removes all handles in @a handle_set.  If @a mask ==
     * ACE_Event_Handler::DONT_CALL then the <handle_close> method of
     * the associated <event_handler>s is not invoked.
     */
    virtual int remove_handler (const ACE_Handle_Set &handle_set,
                                ACE_Reactor_Mask mask) = 0;
  
    /**
     * 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).  Returns 0 on success and
     * -1 if @a signum is invalid.
     */
    virtual int remove_handler (int signum,
                                ACE_Sig_Action *new_disp,
                                ACE_Sig_Action *old_disp = 0,
                                int sigkey = -1) = 0;
  
    /// Calls <remove_handler> for every signal in @a sigset.
    virtual int remove_handler (const ACE_Sig_Set &sigset) = 0;
  
    // = Suspend and resume Handlers.
  
    /// Suspend @a event_handler temporarily.  Use
    /// <ACE_Event_Handler::get_handle> to get the handle.
    virtual int suspend_handler (ACE_Event_Handler *event_handler) = 0;
  
    /// Suspend @a handle temporarily.
    virtual int suspend_handler (ACE_HANDLE handle) = 0;
  
    /// Suspend all @a handles in handle set temporarily.
    virtual int suspend_handler (const ACE_Handle_Set &handles) = 0;
  
    /// Suspend all <handles> temporarily.
    virtual int suspend_handlers (void) = 0;
  
    /// Resume @a event_handler. Use <ACE_Event_Handler::get_handle> to
    /// get the handle.
    virtual int resume_handler (ACE_Event_Handler *event_handler) = 0;
  
    /// Resume @a handle.
    virtual int resume_handler (ACE_HANDLE handle) = 0;
  
    /// Resume all @a handles in handle set.
    virtual int resume_handler (const ACE_Handle_Set &handles) = 0;
  
    /// Resume all <handles>.
    virtual int resume_handlers (void) = 0;
  
    /// 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
    virtual int resumable_handler (void) = 0;
  
    /// Return true if we any event associations were made by the reactor
    /// for the handles that it waits on, false otherwise.
    virtual bool uses_event_associations (void) = 0;
  
    // If we need to reset handles returned from accept/connect.
  
    // = Timer management.
  
    /**
     * Schedule an ACE_Event_Handler that will expire after an amount
     * of time.  The return value of this method, a timer_id value,
     * uniquely identifies the 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.
     *
     * @see cancel_timer()
     * @see reset_timer_interval()
     *
     * @param event_handler  event handler to schedule on reactor
     * @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 after which the timer will be automatically rescheduled
     * @return -1 on failure, a timer_id value on success
     */
    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) = 0;
  
    /**
     * 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.
     */
    virtual int reset_timer_interval (long timer_id,
                                      const ACE_Time_Value &interval) = 0;
  
    /// Cancel all Event_Handlers that match the address of
    /// @a event_handler.  Returns number of handlers cancelled.
    virtual int cancel_timer (ACE_Event_Handler *event_handler,
                              int dont_call_handle_close = 1) = 0;
  
    /**
     * Cancel the single Event_Handler that matches the @a timer_id value
     * (which was returned from the schedule method).  If arg is
     * non-NULL then it will be set to point to the ``magic cookie''
     * argument passed in when the Event_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.
     */
    virtual int cancel_timer (long timer_id,
                              const void **arg = 0,
                              int dont_call_handle_close = 1) = 0;
  
    // = 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.
    virtual int schedule_wakeup (ACE_Event_Handler *event_handler,
                                 ACE_Reactor_Mask masks_to_be_added) = 0;
  
    /// Add @a masks_to_be_added to the @a handle's entry.  <event_handler>
    /// associated with @a handle must already have been registered.
    virtual int schedule_wakeup (ACE_HANDLE handle,
                                 ACE_Reactor_Mask masks_to_be_added) = 0;
  
    /// Clear @a masks_to_be_cleared from the @a event_handler's entry.
    virtual int cancel_wakeup (ACE_Event_Handler *event_handler,
                               ACE_Reactor_Mask masks_to_be_cleared) = 0;
  
    /// Clear @a masks_to_be_cleared from the @a handle's entry.
    virtual int cancel_wakeup (ACE_HANDLE handle,
                               ACE_Reactor_Mask masks_to_be_cleared) = 0;
  
    // = Notification methods.
  
    /**
     * Notify @a event_handler of @a mask event.  The ACE_Time_Value
     * indicates how long to blocking trying to notify.  If @a timeout ==
     * 0, the caller will block until action is possible, else will wait
     * until the relative time specified in @a timeout elapses).
     */
    virtual int notify (ACE_Event_Handler *event_handler = 0,
                        ACE_Reactor_Mask mask = ACE_Event_Handler::EXCEPT_MASK,
                        ACE_Time_Value * = 0) = 0;
  
    /**
     * Set the maximum number of times that ACE_Reactor_Impl 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.
     */
    virtual void max_notify_iterations (int) = 0;
  
    /**
     * Get the maximum number of times that the ACE_Reactor_Impl 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.
     */
    virtual int max_notify_iterations (void) = 0;
  
    /**
     * Purge any notifications pending in this reactor for the specified
     * ACE_Event_Handler object. Returns the number of notifications
     * purged. Returns -1 on error.
     */
    virtual int purge_pending_notifications (ACE_Event_Handler * = 0,
                                             ACE_Reactor_Mask    = ACE_Event_Handler::ALL_EVENTS_MASK) = 0;
  
    /**
     * Return the Event_Handler associated with @a handle.  Return 0 if
     * @a handle is not registered.
     */
    virtual ACE_Event_Handler *find_handler (ACE_HANDLE handle) = 0;
  
    /**
     * Check to see if @a handle is associated with a valid Event_Handler
     * bound to @a mask.  Return the @a event_handler associated with this
     * handler if @a event_handler != 0.
     */
    virtual int handler (ACE_HANDLE handle,
                         ACE_Reactor_Mask mask,
                         ACE_Event_Handler **event_handler = 0) = 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 handler if @a event_handler != 0.
     */
    virtual int handler (int signum,
                         ACE_Event_Handler ** = 0) = 0;
  
    /// Returns true if Reactor has been successfully initialized, else
    /// false.
    virtual bool initialized (void) = 0;
  
    /// Returns the current size of the Reactor's internal descriptor
    /// table.
    virtual size_t size (void) const = 0;
  
    /// Returns a reference to the Reactor's internal lock.
    virtual ACE_Lock &lock (void) = 0;
  
    /// Wake up all threads in waiting in the event loop
    virtual void wakeup_all_threads (void) = 0;
  
    /// Transfers ownership of Reactor_Impl to the @a new_owner.
    virtual int owner (ACE_thread_t new_owner, ACE_thread_t *old_owner = 0) = 0;
  
    /// Return the ID of the "owner" thread.
    virtual int owner (ACE_thread_t *owner) = 0;
  
    /// Get the existing restart value.
    virtual bool restart (void) = 0;
  
    /// Set a new value for restart and return the original value.
    virtual bool restart (bool r) = 0;
  
    /// Set position of the owner thread.
    virtual void requeue_position (int) = 0;
  
    /// Get position of the owner thread.
    virtual int requeue_position (void) = 0;
  
    // = Low-level wait_set mask manipulation methods.
  
    /// GET/SET/ADD/CLR the dispatch mask "bit" bound with the
    /// @a event_handler and @a mask.
    virtual int mask_ops (ACE_Event_Handler *event_handler,
                          ACE_Reactor_Mask mask,
                          int ops) = 0;
  
    /// GET/SET/ADD/CLR the dispatch MASK "bit" bound with the @a handle
    /// and @a mask.
    virtual int mask_ops (ACE_HANDLE handle,
                          ACE_Reactor_Mask mask,
                          int ops) = 0;
  
    // = Low-level ready_set mask manipulation methods.
    /// GET/SET/ADD/CLR the ready "bit" bound with the @a event_handler
    /// and @a mask.
    virtual int ready_ops (ACE_Event_Handler *event_handler,
                           ACE_Reactor_Mask mask,
                           int ops) = 0;
  
    /// GET/SET/ADD/CLR the ready "bit" bound with the @a handle and @a mask.
    virtual int ready_ops (ACE_HANDLE handle,
                           ACE_Reactor_Mask,
                           int ops) = 0;
  
    /// Dump the state of an object.
    virtual void dump (void) const = 0;
  
    /// Declare the dynamic allocation hooks.
    ACE_ALLOC_HOOK_DECLARE;
  };
  
  ACE_END_VERSIONED_NAMESPACE_DECL
  
  #include /**/ "ace/post.h"
  #endif /* ACE_REACTOR_IMPL_H */
  