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-- C974004.A

--

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--

-- OBJECTIVE:

--      Check that the abortable part of an asynchronous select statement

--      is aborted if it does not complete before the triggering statement

--      completes, where the triggering statement is a task entry call,

--      the entry call is queued, and the entry call completes by propagating

--      an exception and that the sequence of statements of the triggering

--      alternative is not executed after the abortable part is left and that

--      the exception propagated by the entry call is re-raised immediately

--      following the asynchronous select.

--

-- TEST DESCRIPTION:

--      Declare a main procedure containing an asynchronous select with a task

--      entry call as triggering statement. Force the entry call to be

--      queued by having the task call a procedure, prior to the corresponding

--      accept statement, which simulates a routine waiting for user input

--      (with a delay).

--

--      Simulate a time-consuming routine in the abortable part by calling a

--      procedure containing an infinite loop. Meanwhile, simulate input by

--      the user (the delay expires), which causes the task to execute the

--      accept statement corresponding to the triggering entry call. Raise

--      an exception in the accept statement which is not handled by the task,

--      and which is thus propagated to the caller.

--

--

-- CHANGE HISTORY:

--      06 Dec 94   SAIC    ACVC 2.0

--

--!

package C974004_0 is  -- Automated teller machine abstraction.

   -- Flags for testing purposes:

   Count                          : Integer := 1234;  -- Global to defeat

                                                      -- optimization.

   Propagated_From_Task : exception;

   type Key_Enum is (None, Cancel, Deposit, Withdraw);

   type Card_Number_Type is private;

   type Card_PIN_Type    is private;

   type ATM_Card_Type    is private;

   Transaction_Canceled : exception;

   task type ATM_Keyboard_Task is

      entry Cancel_Pressed;

   end ATM_Keyboard_Task;

   procedure Read_Card (Card : in out ATM_Card_Type);

   procedure Validate_Card (Card : in ATM_Card_Type);

   procedure Perform_Transaction (Card : in ATM_Card_Type);

private

   type Card_Number_Type is range   1 .. 9999;

   type Card_PIN_Type    is range 100 ..  999;

   type ATM_Card_Type is record

      Number : Card_Number_Type;

      PIN    : Card_PIN_Type;

   end record;

end C974004_0;

     --==================================================================--

with Report;

with ImpDef;

package body C974004_0 is

   procedure Listen_For_Input (Key : out Key_Enum) is

   begin

      -- Simulate the situation where a user waits a bit for the card to

      -- be validated, then presses cancel before it completes.

      -- Delay long enough to force queuing of Keyboard.Cancel_Pressed.

      delay ImpDef.Clear_Ready_Queue;

      if Report.Equal (3, 3) then  -- Always true.

         Key := Cancel;

      end if;

   end Listen_For_Input;

   -- One of these gets created as "Keyboard" for each transaction

   --

   task body ATM_Keyboard_Task is

      Key_Pressed : Key_Enum := None;

   begin

      loop

                                               -- Force entry calls to be

         Listen_For_Input (Key_Pressed);       -- queued, then set guard to

                                               -- true.

         select

            when (Key_Pressed = Cancel) =>     -- Guard is now true, so accept

               accept Cancel_Pressed do        -- queued entry call.

                  null;  --:::: user code for cancel

                  -- Now simulate an unexpected exception arising in the

                  -- user code

                  raise Propagated_From_Task;  -- Propagate an exception.

               end Cancel_Pressed;

               Report.Failed

                          ("Exception not propagated in ATM_Keyboard_Task");

               -- User has canceled the transaction so we exit the

               -- loop and allow the task to terminate

               exit;

         else

            Key_Pressed := None;

         end select;

      end loop;

   exception

      when Propagated_From_Task =>

          null;  -- This is the expected test behavior

      when others =>

          Report.Failed ("Unexpected Exception in ATM_Keyboard_Task");

   end ATM_Keyboard_Task;

   procedure Read_Card (Card : in out ATM_Card_Type) is

   begin

      Card.Number := 9999;

      Card.PIN    := 111;

   end Read_Card;

   procedure Validate_Card (Card : in ATM_Card_Type) is

   begin

      -- Simulate an exceedingly long validation activity.

      loop                                             -- Infinite loop.

         Count := (Count + 1) mod Integer (Card.PIN);

         -- Synch. point to allow transfer of control to Keyboard

         -- task during this simulation

         delay ImpDef.Minimum_Task_Switch;

         exit when not Report.Equal (Count, Count);    -- Always false.

      end loop;

   end Validate_Card;

   procedure Perform_Transaction (Card : in ATM_Card_Type) is

   begin

      Report.Failed ("Exception not re-raised immediately following " &

                     "asynchronous select");

      if Count = 1234 then

         -- Initial value is unchanged

         Report.Failed ("Abortable part did not execute");

      end if;

   end Perform_Transaction;

end C974004_0;

     --==================================================================--

with Report;

with C974004_0;  -- Automated teller machine abstraction.

use  C974004_0;

procedure C974004 is

   Card_Data : ATM_Card_Type;

begin  -- Main program.

   Report.Test ("C974004", "Asynchronous Select: Trigger is queued on a " &

                           "task entry and is completed first by an " &

                           "exception");

   Read_Card (Card_Data);

   begin

      declare

         -- Create the task for this transaction

         Keyboard : C974004_0.ATM_Keyboard_Task;

      begin

         --                                    --

         -- Asynchronous select is tested here --

         --                                    --

         select

            Keyboard.Cancel_Pressed;     -- Entry call initially queued, so

                                         -- abortable part starts.

            raise Transaction_Canceled;  -- Should not be executed.

         then abort

            Validate_Card (Card_Data);   -- Keyboard.Cancel_Pressed is accepted

                                         -- and propagates an exception before

                                         -- this call finishes; it is then

                                         -- aborted.

            -- Check that the whole of the abortable part is aborted, not

            -- just the statement in the abortable part that was executing

            -- at the time

            Report.Failed ("Abortable part not aborted");

         end select;

                                         -- The propagated exception is

                                         -- re-raised here; control passes to

                                         -- the exception handler.

         Perform_Transaction(Card_Data); -- Should not be reached.

      exception

         when Transaction_Canceled =>

            Report.Failed ("Triggering alternative sequence of statements " &

                           "executed");

         when Propagated_From_Task =>

            -- This is the expected test path

            if Count = 1234 then

               -- Initial value is unchanged

               Report.Failed ("Abortable part did not execute");

            end if;

         when Tasking_Error  =>

            Report.Failed ("Tasking_Error raised");

         when others  =>

            Report.Failed ("Wrong exception raised");

      end;

   exception

      when Propagated_From_Task =>

         Report.Failed ("Correct exception raised at wrong level");

      when  others  =>

         Report.Failed ("Wrong exception raised at wrong level");

   end;

   Report.Result;

end C974004;