resmgr_block()
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.
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.
- ETIMEDOUT
- A kernel timeout (that was set with dispatch_timeout() ) unblocked the call.
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 |
Interrupt handler | No |
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() .