RSC/MP Programming Manual

API Function Descriptions RscNotifySem [RSCSEM]
Remarks
Before calling RscNotifySem:
Create a connection handle by calling the RscConnect function.
Create a session handle by calling the RscBeginSession function.
Create a semaphore by using facilities provided by the operating system (see your
operating system programming environment documentation for information about
semaphore creation, use, and management).
Then, call RscNotifySem according to yo ur application‘s needs:
To receive notification of no waited RscWriteRead completions, call RscNotifySem
once with uType set to RSC_NOTIFY_IO before calling RscWriteRead for the first
time. This approach causes RSC/MP to signal your semaphore once for each
subsequent nowaited RscWriteRead completion, until the session ends.
To receive notification of UMS messages, call RscNotifySem once with uType set
to RSC_NOTIFY_UMS. This causes RSC/MP to signal yo ur semaphore once for
each subsequent UMS message received for the session, until the session ends.
You might choose to combine these methods in order to receive notifications of both
types, by calling RscNotifySem twice. In this case, your application should either
supply separate semaphores for I/O and UMS notifications (and then call either
RscIoCheck or RscUmsCheck according to which semaphore is signaled), or supply a
single common semaphore for both (and then call both RscIoCheck and
RscUmsCheck when that semaphore is signaled).
Because a semaphore, when signaled, does no t identify a specific nowaited I/O
handle, an application should generally supply an I/O handle of RSC_IO_CHECK_ALL
when calling RscIoCheck after receiving a notification.
If an application uses multiple concurrent RSC/MP sessions, you must plan your
semaphore notifications carefully. A semaphore, when signaled, does no t identify the
connection or session handle against which an I/O operation completed. Therefore,
your application should either use a separate semaphore for each session (and then
call RscIoCheck only once, supplying the connection and session handles associated
with the particular semaphore that was signaled), or share a single semaphore among
multiple sessions (and call RscIoCheck repeatedly, with all possible connection and
session handles, whe never the shared semaphore is signaled). The same guideline
applies for UMS notifications.
If your semaphore‘s signal count reaches its maximum, RSC/MP queues notifications
internally, and repeatedly attempts to signal the semaphore until all notifications have
been delivered.
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