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-- C974005.A

--

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--

-- OBJECTIVE:

--      Check that Tasking_Error is raised at the point of an entry call

--      which is the triggering statement of an asynchronous select, if

--      the entry call is queued, but the task containing the entry completes

--      before it can be accepted or canceled.

--

--      Check that the abortable part is aborted if it does not complete

--      before the triggering statement completes.

--

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

--      is not executed.

--

-- 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 is NOT the input expected by the

--      guard on the accept statement. The entry remains closed, and the

--      task completes its execution. Since the entry was not accepted before

--      its task completed, Tasking_Error is raised at the point of the entry

--      call.

--

--

-- CHANGE HISTORY:

--      06 Dec 94   SAIC    ACVC 2.0

--

--!

package C974005_0 is  -- Automated teller machine abstraction.

   -- Flags for testing purposes:

   Count : Integer := 1234;

   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 C974005_0;

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

with Report;

with ImpDef;

package body C974005_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 a transaction key (NOT Cancel).

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

      delay ImpDef.Clear_Ready_Queue;

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

         Key := Deposit;           -- Cancel is NOT pressed.

      end if;

   end Listen_For_Input;

   task body ATM_Keyboard_Task is

      Key_Pressed : Key_Enum := None;

   begin

      -- Note: no loop. If the user does not press Cancel, the task completes.

      -- In this model of the keyboard monitor, the user only gets one chance

      -- to cancel the card validation.

                                                            -- Force entry

         Listen_For_Input (Key_Pressed);                    -- calls to be

                                                            -- queued, but do

                                                            -- NOT set guard

                                                            -- to true.

      select

         when (Key_Pressed = Cancel) =>                     -- Guard is false,

            accept Cancel_Pressed do                        -- so entry call

               Report.Failed ("Accept statement executed"); -- remains queued.

            end Cancel_Pressed;

      else                                                  -- Else alternative

         Key_Pressed := None;                               -- executed, then

      end select;                                           -- task ends.

   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.

         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

         -- Additional analysis added to aid developers

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

      end if;

   end Perform_Transaction;

end C974005_0;

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

with Report;

with C974005_0;  -- Automated teller machine abstraction.

use  C974005_0;

procedure C974005 is

   Card_Data : ATM_Card_Type;

begin  -- Main program.

   Report.Test ("C974005", "ATC: trigger is queued but task terminates" &

                             " before call is serviced");

   Read_Card (Card_Data);

   begin

      declare

         Keyboard : C974005_0.ATM_Keyboard_Task;

      begin

         --                                    --

         -- Asynchronous select is tested here --

         --                                    --

         select

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

                                          -- abortable part starts.

                                          -- Tasking_Error raised here when

                                          -- Keyboard completes before entry

                                          -- call can be accepted, and before

                                          -- abortable part completes.

            raise Transaction_Canceled;   -- Should not be executed.

         then abort

            Validate_Card (Card_Data);    -- Keyboard task completes before

                                          -- Keyboard.Cancel_Pressed is

                                          -- accepted, and before this call

                                          -- finishes. Tasking_Error is raised

                                          -- at the point of the entry call,

                                          -- and this call is 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 =>

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

                           "executed");

         when Tasking_Error        =>

            if Count = 1234 then

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

            end if;

         when others       =>

            Report.Failed ("Wrong exception raised");

      end;

   exception

      when Tasking_Error        =>

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

      when others       =>

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

   end;

   Report.Result;

end C974005;