resmgr_block()
QNX SDP8.0C Library ReferenceAPIDeveloper
Block while waiting for a message
Synopsis:
#include <sys/iofunc.h>
#include <sys/dispatch.h>
resmgr_context_t* resmgr_block( resmgr_context_t * ctp );
Arguments:
- ctp
- A pointer to a resmgr_context_t structure that the resource-manager library uses to pass context information between functions.
Library:
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
Description:
The resmgr_block() function waits for a message (created by a call to resmgr_context_alloc()) for context ctp.
Note:
This function is a special case of
dispatch_block()
that you should use only with a simple resource manager.
If you need to attach pulses or other messages, then you should use dispatch_block().
Returns:
The same pointer as ctp, or NULL if an error occurs (errno is set).
Errors:
- EFAULT
- A fault occurred when the kernel tried to access the buffers provided. Because the OS accesses the sender's buffers only when MsgReceive() is called, a fault could occur in the sender if the sender's buffers are invalid. If a fault occurs when accessing the sender buffers (only) they'll receive an EFAULT and the MsgReceive() won't unblock.
- EINTR
- The call was interrupted by a signal.
Examples:
#include <sys/dispatch.h>
#include <stdio.h>
#include <stdlib.h>
int main( int argc, char **argv ) {
dispatch_t *dpp;
resmgr_context_t *ctp;
if ((dpp = dispatch_create()) == NULL) {
fprintf( stderr, "%s: Unable to allocate \
dispatch handle.\n",argv[0] );
return EXIT_FAILURE;
}
…
ctp = resmgr_context_alloc( dpp );
while (1) {
if ( ( ctp = resmgr_block( ctp )) == NULL ) {
fprintf( stderr, "block error\n" );
return EXIT_FAILURE;
}
resmgr_handler( ctp );
}
}
For examples using the dispatch interface, see dispatch_create(), message_attach(), resmgr_attach(), and thread_pool_create().
Classification:
Safety: | |
---|---|
Cancellation point | Yes |
Signal handler | No |
Thread | Yes |
Caveats:
Use resmgr_block() only in a simple resource manager and when you don't use message_attach(), pulse_attach(), or select_attach().
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