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9.7.2 Timed Entry Calls

(1)

A timed_entry_call issues an entry call that is cancelled if the call (or a requeue-with-abort of the call) is not selected before the expiration time is reached.

Syntax

(2)
       timed_entry_call ::=
         select
          entry_call_alternative
         or
          delay_alternative
         end select;
(3)
       entry_call_alternative ::=
         entry_call_statement [sequence_of_statements]

Dynamic Semantics

(4)

For the execution of a timed_entry_call, the entry_name and the actual parameters are evaluated, as for a simple entry call (see 9.5.3). The expiration time (see 9.6) for the call is determined by evaluating the delay_expression of the delay_alternative; the entry call is then issued.

(5)

If the call is queued (including due to a requeue-with-abort), and not selected before the expiration time is reached, an attempt to cancel the call is made. If the call completes due to the cancellation, the optional sequence_of_statements of the delay_alternative is executed; if the entry call completes normally, the optional sequence_of_statements of the entry_call_alternative is executed.

Examples

(6)

Example of a timed entry call:

(7)
       select
          Controller.Request(Medium)(Some_Item);
       or
          delay 45.0;
          --  controller too busy, try something else
       end select;

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