3 -- Grant of Unlimited Rights
5 -- Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,
6 -- F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained
7 -- unlimited rights in the software and documentation contained herein.
8 -- Unlimited rights are defined in DFAR 252.227-7013(a)(19). By making
9 -- this public release, the Government intends to confer upon all
10 -- recipients unlimited rights equal to those held by the Government.
11 -- These rights include rights to use, duplicate, release or disclose the
12 -- released technical data and computer software in whole or in part, in
13 -- any manner and for any purpose whatsoever, and to have or permit others
18 -- ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR
19 -- DISCLOSED ARE AS IS. THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED
20 -- WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE
21 -- SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE
22 -- OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
23 -- PARTICULAR PURPOSE OF SAID MATERIAL.
25 -- CHECK THAT NO RENDEZVOUS CAN EVER OCCUR IF BOTH PARTNERS REFUSE TO
26 -- WAIT (THAT IS, IF THE ENTRY CALL IS ISSUED BY A
27 -- "CONDITIONAL_ENTRY_CALL" AND THUS FOLLOWS A NO-WAIT POLICY
28 -- (DEMANDING UNCONDITIONALLY THAT "YOU DO IT N O W , OR ELSE"),
29 -- WHILE THE CALLEE IS ALSO COMMITTED TO A NO-WAIT POLICY,
30 -- BY VIRTUE OF A SELECTIVE_WAIT STATEMENT OF THE THIRD KIND
31 -- (WITH AN "ELSE" PART) IN WHICH THE CORRESPONDING ACCEPT_STATEMENT
33 -- ("CLOSE ENCOUNTERS OF THE THIRD KIND" -- ARE THEY POSSIBLE?)
36 -- THE SEMANTICS OF THIS ENTRY CALL REQUIRES THAT THE CALLING TASK
37 -- N O T ENTER ITSELF ON ANY QUEUE BUT RATHER ATTEMPT AN IMMEDIATE
38 -- RENDEZVOUS WHICH IS TO TAKE PLACE IF AND ONLY IF THE CALLED TASK
39 -- HAS REACHED A POINT WHERE IT IS READY TO ACCEPT THE CALL (I.E.
40 -- IT IS EITHER WAITING AT AN ACCEPT STATEMENT FOR THE CORRESPONDING
41 -- ENTRY OR IT IS WAITING AT A SELECTIVE_WAIT STATEMENT WITH AN OPEN
42 -- ALTERNATIVE STARTING WITH SUCH AN ACCEPT STATEMENT). IT ALSO
43 -- REQUIRES THAT THE ENTRY CALL BE CANCELLED IF THE CALLED TASK
44 -- IS NOT AT SUCH A POINT. ON THE OTHER HAND, THE SEMANTICS OF THE
45 -- SELECTIVE_WAIT STATEMENT WITH AN 'ELSE' PART SPECIFIES THAT
46 -- THE 'ELSE' PART MUST BE SELECTED IF NO 'ACCEPT' ALTERNATIVE
47 -- CAN BE IMMEDIATELY SELECTED, AND THAT SUCH AN ALTERNATIVE
48 -- IS DEEMED TO BE IMMEDIATELY SELECTABLE ("SELECTION OF ONE SUCH
49 -- ALTERNATIVE OCCURS IMMEDIATELY"), AND A CORRESPONDING RENDEZVOUS
50 -- POSSIBLE, IF AND ONLY IF THERE IS A CORRESPONDING ENTRY CALL
51 -- W A I T I N G TO BE ACCCEPTED. A "CONDITIONAL ENTRY CALL"
52 -- NEVER WAITS, AND IS NEVER ENTERED IN WAIT QUEUES; IT TAKES
53 -- THE 'ELSE' PART INSTEAD.
56 -- NOTE: IF THIS TEST PROGRAM HANGS UP, THE COMPILER WILL BE DEEMED
63 WITH REPORT
; USE REPORT
;
66 RENDEZVOUS_OCCURRED
: BOOLEAN := FALSE ;
68 CALLER_TAKES_WRONG_BRANCH
: BOOLEAN := TRUE ;
69 SERVER_TAKES_WRONG_BRANCH
: BOOLEAN := TRUE ;
70 QUEUE_NOT_EMPTY
: BOOLEAN := FALSE ;
75 TEST
("C97201X", "CHECK THAT NO RENDEZVOUS CAN EVER OCCUR IF" &
76 " BOTH PARTNERS REFUSE TO WAIT" );
84 ENTRY DO_IT_NOW_ORELSE
( DID_YOU_DO_IT
: IN OUT BOOLEAN);
96 IF DO_IT_NOW_ORELSE
'COUNT /= 0 THEN
97 QUEUE_NOT_EMPTY
:= TRUE ;
102 ACCEPT DO_IT_NOW_ORELSE
103 ( DID_YOU_DO_IT
: IN OUT BOOLEAN )
105 DID_YOU_DO_IT
:= TRUE ;
107 ELSE -- (I.E. TASK ADOPTS NO-WAIT POLICY)
108 -- 'ELSE' BRANCH MUST THEREFORE BE CHOSEN
109 SERVER_TAKES_WRONG_BRANCH
:= FALSE ;
113 IF DO_IT_NOW_ORELSE
'COUNT /= 0 THEN
114 QUEUE_NOT_EMPTY
:= TRUE ;
118 ACCEPT KEEP_ALIVE
; -- TO PREVENT THIS SERVER TASK FROM
119 -- TERMINATING IF IT GETS TO
120 -- THE NO-WAIT MEETING-PLACE
121 -- AHEAD OF THE CALLER (WHICH
122 -- WOULD LEAD TO A SUBSEQUENT
123 -- TASKING_ERROR AT THE TIME OF
124 -- THE NO-WAIT CALL).
133 T
.SYNCHRONIZE
; -- TO MINIMIZE THE N E E D TO WAIT
137 T
.DO_IT_NOW_ORELSE
( RENDEZVOUS_OCCURRED
);
138 ELSE -- (I.E. CALLER TOO ADOPTS A NO-WAIT POLICY)
139 -- MUST THEREFORE CHOOSE THIS BRANCH
140 CALLER_TAKES_WRONG_BRANCH
:= FALSE ;
144 T
.KEEP_ALIVE
; -- THIS ALSO UPDATES THE NONLOCALS
147 END; -- END OF BLOCK CONTAINING THE NO-WAIT ENTRY CALL
150 IF RENDEZVOUS_OCCURRED
152 FAILED
( "RENDEZVOUS OCCURRED" );
155 IF CALLER_TAKES_WRONG_BRANCH
OR
156 SERVER_TAKES_WRONG_BRANCH
158 FAILED
( "WRONG BRANCH TAKEN" );
163 FAILED
( "ENTRY QUEUE NOT EMPTY" );