pSOSystem System Calls - Read

pSOS+ System Calls t_delete
Notes
1. If the call is to delete self (suicide via tid equal to 0), there will be no return.
2. Task deletion should be carefully planned and considered. Indiscriminate use
can lead to unpredictable results, especially when resources such as allocated
memory segments, buffers, or semaphores have not been correctly returned. If a
task holds any resources from the pREPC+ library, the pHILE+ file system
manager, or the pNA+ network manager, those resources must be returned
before t_delete() is called. The commands that must be executed for
pREPC+, pHILE+, and pNA+ resources are fclose(0), close_f(0), and
close(0), respectively. Following these commands, a free() command must
be used to return pREPC+ memory. This order of execution is required because
the pREPC+ library calls the pHILE+ file system manager, and the pHILE+ file
system manager calls the pNA+ network manager (if NFS is in use.) If resources
are not returned in the correct order, an error occurs. See Error Codes.
The following is an example of the correct sequence of calls for returning resources.
This example applies to a case where all three components have allocated
resources:
fclose(0); /* return pREPC+ resources */
close_f(0); /* return pHILE+ resources */
close(0); /* return pNA+ resources */
free(-1) /* return pREPC+ memory */
t_delete(0); /* and execute self-deletion */
3. Using t_delete() to delete another task does not generally allow that task a
chance to perform any cleanup work necessary for the orderly termination of
the task. In general, t_delete() should be used for self-deletion, whereas
asynchronous deletion of another task can best be achieved using the
t_restart() call.
4. t_delete() calls the optional user-supplied callout procedure, whose address
is defined in the kc_deleteco entry in the pSOS+ Configuration Table.
Multiprocessor Considerations
1. A task can be deleted only from the local node.
2. If tid identifies a global task, t_delete notifies the master node so that the
task can be removed from its Global Object Table. Thus, deletion of a global
task always causes activity on the master node.
pSOSystem System Calls 1-139
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