9.7.3 Conditional Entry Calls
issues an entry call that is then cancelled if it is not selected immediately
(or if a requeue-with-abort of the call is not selected immediately). A procedure call may appear rather than an entry call for cases where
the procedure might be implemented by an entry.
To be honest: In the case of an entry
call on a protected object, it is OK if the entry is closed at the start
of the corresponding protected action, so long as it opens and the call
is selected before the end of that protected action (due to changes in
the Count attribute).
41 A conditional_entry_call
may briefly increase the Count attribute of the entry, even if the conditional
call is not selected.
Example of a conditional
procedure Spin(R : in Resource) is
null; -- busy waiting
Wording Changes from Ada 83
This subclause clause
comes after the one for Timed Entry Calls, so we can define conditional
entry calls in terms of timed entry calls. We do that so that an "expiration
time" is defined for both, thereby simplifying the definition of
what happens on a requeue-with-abort.
Ada 2005 and 2012 Editions sponsored in part by Ada-Europe