iofunc_notify_trigger()

Send notifications to queued clients

Synopsis:

#include <sys/iofunc.h>

void iofunc_notify_trigger( iofunc_notify_t *nop,
                            int count,
                            int index );

An array of three iofunc_notify_t structures that represent (in order), the input, output, and out-of-band notification lists whose entries you want to examine; for information about this structure, see the documentation for iofunc_notify().

count

The count that you want to compare to the trigger value for the event.

index

The index into the nop array that you want to check; one of the following:

IOFUNC_NOTIFY_INPUT
IOFUNC_NOTIFY_OUTPUT
IOFUNC_NOTIFY_OBAND

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The iofunc_notify_trigger() function examines all entries given in the list maintained at nop [index] to see if the event should be delivered to the client. If the specified count is greater than or equal to the trigger count for the particular notification list element, this function calls MsgDeliverEvent() to deliver the event to the client whose rcvid is stored in the notification list element, and the list element is disarmed.

Note that if the client has specified a code of SI_NOTIFY, then the value that the client specified (e.g. the value member of the struct sigevent) has the top three bits ORed with the reason for the trigger (this is the expression _NOTIFY_COND_INPUT << index), as in the following table:

index = IOFUNC_NOTIFY_INPUT: 0x10000000, or _NOTIFY_COND_INPUT
index = IOFUNC_NOTIFY_OUTPUT: 0x20000000, or _NOTIFY_COND_OUTPUT
index = IOFUNC_NOTIFY_OBAND: 0x40000000, or _NOTIFY_COND_OBAND

If the client has specified a code of something other than SI_NOTIFY then this routine doesn't modify the value member in any way.

The sys/iofunc.h file also defines the IOFUNC_NOTIFY_INPUT_CHECK(), IOFUNC_NOTIFY_OUTPUT_CHECK(), and IOFUNC_NOTIFY_OBAND_CHECK() macros, which you can use to see if there are enough bytes in the lists to make it worthwhile to call iofunc_notify_trigger() to notify clients about:

#define IOFUNC_NOTIFY_INPUT_CHECK(__nop, __cnt, __tran)	...
#define IOFUNC_NOTIFY_OUTPUT_CHECK(__nop, __cnt) ...
#define IOFUNC_NOTIFY_OBAND_CHECK(__nop, __cnt, __tran)	...

The arguments are:

__nop: An array of three iofunc_notify_t structures that represent (in order), the input, output, and out-of-band notification lists whose entries you want to examine.
__cnt: The count that you want to compare to the trigger value for the event.
__tran: (IOFUNC_NOTIFY_INPUT_CHECK() and IOFUNC_NOTIFY_OBAND_CHECK() only) Nonzero if you want to arm the trigger when the list makes the transition from empty to nonempty (for example, as mq_notify() does).

Examples:

See Writing a Resource Manager

Classification:

QNX Neutrino

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	Yes
Thread	Yes