srv_event_deferred

Description

Add an event request to the event queue of a thread as the result of an asynchronous event.

Syntax

CS_INT srv_event_deferred(spp, event, datap)

SRV_PROC    *spp;
CS_INT           event;
CS_VOID       *datap;

Parameters

Returns

The requested event. If there was an error, -1 is returned.

Examples

Example 1

#include   <ospublic.h>

/*

 ** Local Prototype

 */

CS_RETCODE   ex_srv_event_deferred PROTOTYPE((

SRV_PROC     *spp,

CS_INT       event,

CS_VOID      *datap

));

/* 

 ** EX_SRV_EVENT_DEFERRED

**    Example routine to queue up a deferred event using

 **    srv_event_deferred. A deferred event request will 

 **    typically be made from within interrupt-level code.

** Arguments:

**    spp       A pointer to the internal thread control 

 **              structure.

**    event     The event to add to the thread’s queue.

**    datap     A pointer to data to attach to the event.

** Returns:

**    CS_SUCCEED    The event was sucecssfully queued.

**    CS_FAIL       An error was detected.

 */

CS_RETCODE          ex_srv_event_deferred(spp, event, datap)

SRV_PROC            *spp;

CS_INT              event;

CS_VOID             *datap;

{

      /*

      ** Add a deferred event to the event queue.

      */

     if (srv_event_deferred(spp, event, datap) == -1)

     {

            return(CS_FAIL);

      }

     return(CS_SUCCEED);

}

Usage

• srv_event_deferred adds an event request to the event queue of a thread from interrupt-level code, such as signal delivery on UNIX. The event request is deferred until critical functions internal to Open Server have been completed, if any such functions were being performed when srv_event_deferred was called.

• Some Open Server applications must be able to raise events from interrupt-level code. For example, if you want to raise an event within the attention handler or you are using the alarm signal in the Open Server application code, you must use srv_event_deferred instead of srv_event. srv_event_deferred ensures that critical functions, such as updating linked lists or performing internal housekeeping, are completed before the event request is acted on.

  WARNING! In interrupt-level code, use srv_event_deferred instead of srv_event.

• Open Server usually adds event requests to a thread’s event request queue automatically. However, you can specifically add requests with srv_event_deferred.

• The following events can be added to an event queue by srv_event_deferred:

  • SRV_DISCONNECT

  • SRV_URGDISCONNECT

  • SRV_STOP

  • Programmer-defined events

• srv_handle tells the Open Server which event handler to call when an event occurs. If no handler is defined for a particular event, the default event Open Server handler is called.

• If the event is programmer-defined, it must be defined with srv_define_event before it can be triggered.

• srv_event adds any event except SRV_STOP or SRV_START to a thread’s event queue. In the case of a SRV_STOP or SRV_START event, spp points to the internal thread control structure for the thread requesting the event.

• An Open Server application cannot call any routine that does I/O from inside a user-defined event.

See also