T-Kernel Specification (1.B0.02)

4.5. EXTENDED SYNCHRONIZATION AND COMMUNICATION FUNCTIONS 143
[Additional Notes]
If a task calling a rendezvous aborts for some reason before completion of the rendezvous (before
tk rpl rdv is executed), the accepting task has no direct way of knowing of the abort. In such a
case, error code E OBJ is returned to the rendezvous accepting task when it executes tk rpl rdv.
After a rendezvous is established, tasks are in principle detached from the rendezvous port and have
no need to reference information about each other. However, since the value of maxrmsz, used when
checking the length of the reply message sent using tk rpl rdv, is dependent on the rendezvous port,
the task in rendezvous must record this information somewhere. One possible implementation would be
to put this information in the TCB of the calling task after it goes to WAIT state, or in another area
that can be referenced from the TCB, such as a stack area.
[Rationale for the Specification]
The parameter rdvno is passed to tk rpl rdv and tk fwd por as information for distinguishing one
established rendezvous from another, but the rendezvous port ID (porid) used when establishing a
rendezvous is not designated. This is based on the design principle that tasks are no longer related to
rendezvous ports after a rendezvous has been established.
Error code E OBJ rather than E PAR is returned for an invalid rdvno. This is because rdvno itself is an
object indicating the task that called the rendezvous.
Copyright c○ 2002, 2003 by T-Engine Forum
T-Kernel 1.B0.02