| -- C954A01.A |
| -- |
| -- Grant of Unlimited Rights |
| -- |
| -- 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 without abort on a protected entry queue |
| -- is aborted, the abort is deferred until the entry call completes, |
| -- after which the 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 not aborted. Call the second protected |
| -- procedure of the protected type (the interrupt handler) and verify that |
| -- the protected entry completes for the requesting task. Verify that |
| -- the requesting task is then aborted. |
| -- |
| -- 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 C954A01_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 C954A01_0; |
| |
| |
| --==================================================================-- |
| |
| |
| with Report; |
| with ImpDef; |
| |
| with F954A00; -- Printer device abstraction. |
| use F954A00; |
| pragma Elaborate(F954A00); |
| |
| package body C954A01_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. |
| 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 |
| -- 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; |
| |
| -- Allow other tasks to get control |
| delay ImpDef.Minimum_Task_Switch; |
| |
| end loop; |
| |
| exception |
| when others => |
| Report.Failed ("Exception raised in Printer_Server task"); |
| end Printer_Server; |
| |
| |
| end C954A01_0; |
| |
| |
| --==================================================================-- |
| |
| |
| with Report; |
| with ImpDef; |
| |
| with F954A00; -- Printer device abstraction. |
| with C954A01_0; -- Printer server abstraction. |
| |
| use C954A01_0; |
| use F954A00; |
| |
| procedure C954A01 is |
| |
| Long_Enough : constant Duration := ImpDef.Switch_To_New_Task; |
| |
| --==============================================-- |
| |
| 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 ("C954A01", "Requeue without abort - check that the abort " & |
| "is deferred until after the rendezvous completes. (Task to PO)"); |
| |
| -- To pass this test, the following must be true: |
| -- |
| -- (A) The abort of Print_Request is deferred until after the |
| -- Done_Printing entry body completes. |
| -- (B) Print_Request aborts after the Done_Printing entry call |
| -- completes. |
| -- |
| -- 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. |
| |
| -- 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 |
| -- abort to complete (if it's going |
| -- to). |
| |
| -- Verify that the Done_Printing entry body has not yet completed, |
| -- and thus that Print_Request has not been aborted. |
| |
| if Printer(1).Is_Done then |
| Report.Failed ("Target entry of requeue executed prematurely"); |
| elsif Print_Request'Terminated then |
| Report.Failed ("Caller was aborted before entry was complete"); |
| else |
| |
| Printer(1).Handle_Interrupt; -- Simulate a printer interrupt, |
| -- signaling that printing is |
| -- done. |
| |
| -- The Done_Printing entry body will complete before the next protected |
| -- action is called (Printer(1).Is_Done). Verify (A) and (B): that the |
| -- Print_Request is aborted. |
| |
| Printer_Server.Verify_Results; -- Abortion completion point: force |
| -- Print_Request abort to complete. |
| |
| if not Printer(1).Is_Done then |
| Report.Failed ("Target entry of requeue did not complete"); |
| end if; |
| |
| if not Print_Request'Terminated then |
| Report.Failed ("Task not aborted following completion of entry call"); |
| abort Print_Request; -- Try to kill hung task. |
| end if; |
| |
| end if; |
| |
| Report.Result; |
| |
| end C954A01; |
