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-- C974003.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, and

--      the entry call is queued.

--

--      Check that the sequence of statements of the triggering alternative

--      is executed after the abortable part is left.

--

-- 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.

--

--

-- CHANGE HISTORY:

--      06 Dec 94   SAIC    ACVC 2.0

--

--!

package C974003_0 is  -- Automated teller machine abstraction.

   -- Flags for testing purposes:

   --

   TC_Triggering_Statement_Completed : Boolean := False;

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

                                                         -- optimization.

   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 C974003_0;

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

with Report;

with ImpDef;

package body C974003_0 is

   procedure Listen_For_Input (Key : out Key_Enum) is

   begin

      -- Model the situation where the 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.Minimum_Task_Switch;

      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

         Listen_For_Input (Key_Pressed);                   -- to be queued,

                                                           -- then set guard to

                                                           -- true.

         select

            when (Key_Pressed = Cancel) =>                 -- Guard is now

               accept Cancel_Pressed do                    -- true, so accept

                  TC_Triggering_Statement_Completed := True;  -- queued entry

               end Cancel_Pressed;                         -- call.

               -- User has cancelled the transaction so we exit the

               -- loop and allow the task to terminate

               exit;

         else

            Key_Pressed := None;

         end select;

      end loop;

   exception

      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.

         TC_Count := (TC_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 (TC_Count, TC_Count);    -- Always false.

      end loop;

   end Validate_Card;

   procedure Perform_Transaction (Card : in ATM_Card_Type) is

   begin

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

                     "not executed");

      if not TC_Triggering_Statement_Completed then

         Report.Failed ("Triggering statement did not complete");

      end if;

      if TC_Count = 1234 then

         -- Initial value is unchanged

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

      end if;

   end Perform_Transaction;

end C974003_0;

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

with Report;

with C974003_0;  -- Automated teller machine abstraction.

use  C974003_0;

procedure C974003 is

   Card_Data : ATM_Card_Type;

begin  -- Main program.

   Report.Test ("C974003", "Asynchronous Select: Trigger is queued on a " &

                            "task entry and completes first");

   Read_Card (Card_Data);

   declare

      -- Create the task for this transaction

      Keyboard : C974003_0.ATM_Keyboard_Task;

   begin

      --                                    --

      -- Asynchronous select is tested here --

      --                                    --

      select

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

                                       -- abortable part starts.

         raise Transaction_Canceled;   -- This is executed after Validate_Card

                                       -- is aborted.

      then abort

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

                                       -- and completes 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;

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

   exception

      when Transaction_Canceled =>

         if not TC_Triggering_Statement_Completed then

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

                           "executed but triggering statement not complete");

         end if;

         if TC_Count = 1234 then

            -- Initial value is unchanged

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

         end if;

   end;

   Report.Result;

end C974003;