c954a02.a

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-- C954A02.A
--
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--     Under contracts F33600-87-D-0337, F33600-84-D-0280, MDA903-79-C-0687,
--     F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained 
--     unlimited rights in the software and documentation contained herein.
--     Unlimited rights are defined in DFAR 252.227-7013(a)(19).  By making 
--     this public release, the Government intends to confer upon all 
--     recipients unlimited rights  equal to those held by the Government.  
--     These rights include rights to use, duplicate, release or disclose the 
--     released technical data and computer software in whole or in part, in 
--     any manner and for any purpose whatsoever, and to have or permit others 
--     to do so.
--
--                                    DISCLAIMER
--
--     ALL MATERIALS OR INFORMATION HEREIN RELEASED, MADE AVAILABLE OR
--     DISCLOSED ARE AS IS.  THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED 
--     WARRANTY AS TO ANY MATTER WHATSOEVER, INCLUDING THE CONDITIONS OF THE
--     SOFTWARE, DOCUMENTATION OR OTHER INFORMATION RELEASED, MADE AVAILABLE 
--     OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
--     PARTICULAR PURPOSE OF SAID MATERIAL.
--*
--
-- OBJECTIVE:
--      Check that if a task requeued with abort on a protected entry queue
--      is aborted, the protected entry call is canceled and the aborted
--      task becomes completed.
--
-- TEST DESCRIPTION:
--      Declare a protected type which simulates a printer device driver
--      (foundation code).
--
--      Declare a task which simulates a printer server for multiple printers.
--
--      For the protected type, declare an entry with a barrier that is set
--      false by a protected procedure (which simulates starting a print job
--      on the printer), and is set true by a second protected procedure (which
--      simulates a handler called when the printer interrupts, indicating
--      that printing is done).
--
--      For the task, declare an entry whose corresponding accept statement
--      contains a call to first protected procedure of the protected type
--      (which sets the barrier of the protected entry to false), followed by
--      a requeue with abort to the protected entry. Declare a second entry
--      which does nothing.
--
--      Declare a "requesting" task which calls the printer server task entry
--      (and thus executes the requeue). Attempt to abort the requesting
--      task. Verify that it is aborted, that the requeued entry call is
--      canceled, and that the corresponding entry body is not executed.
--
-- TEST FILES:
--      This test depends on the following foundation code:
--
--         F954A00.A
--
--
--
-- CHANGE HISTORY:
--      06 Dec 94   SAIC    ACVC 2.0
--      10 Oct 96   SAIC    Added pragma elaborate
--
--!

package C954A02_0 is  -- Printer server abstraction.

   -- Simulate a system with multiple printers. The entry Print requests
   -- that data be printed on the next available printer. The entry call
   -- is accepted when a printer is available, and completes when printing
   -- is done.


   task Printer_Server is
      entry Print (File_Name : String);        -- Test the requeue statement.
      entry Verify_Results;                    -- Artifice for test purposes.
   end Printer_Server;

end C954A02_0;


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


with Report;
with ImpDef;

with F954A00;              -- Printer device abstraction.
use  F954A00;
pragma Elaborate(F954a00);

package body C954A02_0 is  -- Printer server abstraction.

   task body Printer_Server is
      Printers_Busy  : Boolean    := True;
      Index          : Printer_ID := 1;
      Print_Accepted : Boolean    := False;
   begin

      loop
         -- Wait for a printer to become available:

         while Printers_Busy loop
            Printers_Busy := False;                        -- Exit loop if
                                                           -- entry accepted.
            select
               Printer(Index).Done_Printing;               -- Accepted immed.
                                                           -- when printer is
                                                           -- available.
            else
               Index := 1 + (Index mod Number_Of_Printers);-- Entry not immed.
               Printers_Busy := True;                      -- accepted; keep
            end select;                                    -- looping.

            -- Allow other task to get control
            delay ImpDef.Minimum_Task_Switch;  

         end loop;                                         -- Value of Index
                                                           -- at loop exit
                                                           -- identifies the
                                                           -- avail. printer.

         -- Wait for a print request or terminate:

         select
            accept Print (File_Name : String) do
               Print_Accepted := True;                     -- Allow
                                                           -- Verify_Results
                                                           -- to be accepted.

               Printer(Index).Start_Printing (File_Name);  -- Begin printing on
                                                           -- the available
               --                        --                -- printer.
               -- Requeue is tested here --
               --                        --
                                                           -- Requeue caller so
               requeue Printer(Index).Done_Printing        -- server task free
                 with abort;                               -- to accept other
            end Print;                                     -- requests.
         or
            -- Guard ensures that Verify_Results cannot be accepted
            -- until after Print has been accepted. This avoids a
            -- race condition in the main program.

            when Print_Accepted => accept Verify_Results;  -- Artifice for
                                                           -- testing purposes.
         or
            terminate;
         end select;

      end loop;

   exception
      when others =>
         Report.Failed ("Exception raised in Printer_Server task");
   end Printer_Server;


end C954A02_0;


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


with Report;
with ImpDef;

with F954A00;    -- Printer device abstraction.
with C954A02_0;  -- Printer server abstraction.

use  C954A02_0;
use  F954A00;

procedure C954A02 is

   -- Length of time which simulates a very long process
   Long_Enough : constant Duration := ImpDef.Clear_Ready_Queue;

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

   task Print_Request;                       -- Send a print request.

   task body Print_Request is
      My_File : constant String := "MYFILE.DAT";
   begin
      Printer_Server.Print (My_File);          -- Invoke requeue statement.
      Report.Failed ("Task continued execution following entry call");
   exception
      when others =>
         Report.Failed ("Exception raised in Print_Request task");
   end Print_Request;

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

begin  -- Main program.

   Report.Test ("C954A02", "Abort a requeue on a Protected entry");

   -- To pass this test, the following must be true:
   --
   --    (A) The abort of Print_Request takes place immediately.
   --    (B) The Done_Printing entry call is canceled, and the corresponding
   --        entry body is not executed.
   --
   -- Call the entry Verify_Results. The entry call will not be accepted
   -- until after Print_Request has been requeued to Done_Printing.

   Printer_Server.Verify_Results;           -- Accepted after Print_Request is
                                            -- requeued to Done_Printing.

   -- Verify that the Done_Printing entry call has not been completed.
   --
   if Printer(1).Is_Done then
      Report.Failed ("Target entry of requeue executed prematurely");
   else

      -- Simulate an application which needs access to the printer within
      -- a specified time, and which aborts the current printer job if time
      -- runs out.

      select
         Printer(1).Done_Printing;          -- Wait for printer to come free.
      or
         delay Long_Enough;                 -- Print job took too long.
         abort Print_Request;               -- Abort print job.
      end select;

      Printer_Server.Verify_Results;        -- Abortion completion point: force
                                            -- Print_Request abort to complete.

      -- Verify (A): that Print_Request has been aborted.
      -- Note: the test will hang if the task as not been aborted
      --
      while not Print_Request'Terminated loop
         delay ImpDef.Minimum_Task_Switch;  
      end loop;

      -- Verify (B): that the Done_Printing entry call was canceled, and
      -- the corresponding entry body was not executed.
      --
      -- Set the barrier of the entry to true, then check that the entry
      -- body is not executed. If the entry call is NOT canceled, the
      -- entry body will execute when the barrier is set true.

      Printer(1).Handle_Interrupt;       -- Simulate a printer interrupt,
                                         -- signaling that printing is
                                         -- done.
      if Printer(1).Is_Done then
         Report.Failed ("Entry call was not canceled");
      end if;


   end if;


   Report.Result;

end C954A02;