Create a connection to a channel
#include <sys/iofunc.h> #include <sys/dispatch.h> int message_connect( dispatch_t * dpp, int flags );
libc
Use the -l c option to qcc to link against this library. This library is usually included automatically.
The message_connect() function creates a connection to the channel used by dispatch handle dpp. This function calls the ConnectAttach() kernel call. To detach the connection ID, you can call ConnectDetach().
The message_connect() function works only when the dispatch blocking type is receive, i.e. attaches were done for resmgr, message, or select “type” events. If no attaches were done yet, the message_connect() call fails, since dispatch can't determine if receive or sigwait blocking will be used. |
A connection ID used by the message primitives, or -1 if an error occurs (errno is set).
#include <sys/dispatch.h> #include <time.h> #include <stdio.h> #include <stdlib.h> int main( int argc, char **argv ) { dispatch_t *dpp; int flags, coid, id; if( ( dpp = dispatch_create() ) == NULL ) { fprintf( stderr, "%s: Unable to allocate dispatch context.\n", argv[0] ); return EXIT_FAILURE; } id = resmgr_attach ( … ); … if ( (coid = message_connect ( dpp, flags )) == -1 ) { fprintf ( stderr, "Failed to create connection \ to channel used by dispatch.\n"); return 1; } /* else connection to channel used by dispatch is created */ … }
For examples using the dispatch interface, see dispatch_create(), message_attach(), resmgr_attach(), and thread_pool_create().
Safety: | |
---|---|
Cancellation point | Yes |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |
Dispatch dpp must block on messages.
ConnectAttach(), message_attach()
“Layers in a resource manager” in the Bones of a Resource Manager chapter of Writing a Resource Manager