9.7.3 Conditional Entry Calls

1. A conditional_entry_call 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).
   Syntax
   

2. conditional_entry_call ::=
      select
         entry_call_alternative
      else
         sequence_of_statements
      end select;
   

   Dynamic Semantics
   
3. The execution of a conditional_entry_call is defined to be equivalent to the execution of a timed_entry_call with a delay_alternative specifying an immediate expiration time and the same sequence_of_statements as given after the reserved word else.
   

   NOTES
   

4. (37) A conditional_entry_call may briefly increase the Count attribute of the entry, even if the conditional call is not selected.
   Examples
   
5. Example of a conditional entry call:

6. procedure Spin(R : in Resource) is
   begin
      loop
         select
            R.Seize;
            return;
         else
            null;  --  busy waiting
         end select;
      end loop;
   end;
   

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