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-- C954024.A

--

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--

-- OBJECTIVE:

--      Check that a call to a protected entry can be requeued to a task

--      entry. Check that the requeue is placed on the correct entry; that the

--      original caller waits for the completion of the requeue and continues

--      after the requeued rendezvous.  Check that the requeue does not block.

--      Specifically, check a requeue without abort from a protected entry to

--      an entry in a task.

--

-- TEST DESCRIPTION:

--      In the Distributor protected object, requeue two successive calls on

--      the entries of two separate target tasks.  Each task in each of the

--      paths adds identifying information in the transaction being passed.

--      This information is checked by the Message tasks on completion

--      ensuring that the requeues have been placed on the correct queues.

--      There is an artificial guard on the Credit Task to ensure that the

--      input is queued; this guard is released by the Debit task which

--      handles its input immediately.  This ensures that we have one of the

--      requeued items actually queued for later handling and also verifies

--      that the requeuing process (in the protected object) is not blocked.

--

--      This series of tests uses a simulation of a transaction driven

--      processing system.  Line Drivers accept input from an external source

--      and build them into transaction records.  These records are then

--      encapsulated in message tasks which remain extant for the life of the

--      transaction in the system. The message tasks put themselves on the

--      input queue of a Distributor object which, from information in the

--      transaction and/or system load conditions forwards them to other

--      operating tasks. These in turn might forward the transactions to yet

--      other tasks for further action.  The routing is, in real life,

--      dynamic and unpredictable at the time of message generation. All

--      rerouting in this  model is done by means of requeues.

--

--

-- CHANGE HISTORY:

--      06 Dec 94   SAIC    ACVC 2.0

--      08 Nov 95   SAIC    Fixed reported problems for ACVC 2.0.1

--

--!

with Report;

with ImpDef;

procedure C954024 is

begin -- C954024

   Report.Test ("C954024", "Requeue from protected entry to task entry");

   declare -- encapsulate the test

      -- Arbitrary test values

      Credit_Return : constant := 1;

      Debit_Return  : constant := 2;

      type Transaction_Code is (Credit, Debit);

      type Transaction_Record;

      type acc_Transaction_Record is access Transaction_Record;

      type Transaction_Record is

         record

            ID               : integer := 0;

            Code             : Transaction_Code := Debit;

            Account_Number   : integer := 0;

            Stock_Number     : integer := 0;

            Quantity         : integer := 0;

            Return_Value     : integer := 0;

            TC_Message_Count : integer := 0;

            TC_Thru_Dist     : Boolean := false;

         end record;

      task type Message_Task is

         entry Accept_Transaction (In_Transaction : acc_Transaction_Record);

      end Message_Task;

      type acc_Message_Task is access Message_Task;

      task Line_Driver is

         entry Start;

      end Line_Driver;

      task Credit_Computation is

         entry Input(Transaction : acc_Transaction_Record);

      end Credit_Computation;

      task Debit_Computation is

         entry Input(Transaction : acc_Transaction_Record);

      end Debit_Computation;

      protected Time_Lock is

         procedure Credit_Start;

         function  Credit_Enabled return Boolean;

      private

         Credit_OK : Boolean := false;

      end Time_Lock;

      protected body Time_Lock is

         procedure Credit_Start is

         begin

            Credit_OK := true;

         end Credit_Start;

         function  Credit_Enabled return Boolean is

         begin

            return Credit_OK;

         end Credit_Enabled;

      end Time_Lock;

      protected Distributor is

         entry Input (Transaction : acc_Transaction_Record);

      end Distributor;

      --

      --

      -- Dispose each input Transaction_Record to the appropriate

      -- computation tasks

      --

      protected body Distributor is

         entry Input (Transaction : acc_Transaction_Record) when true is

                                                   -- barrier is always open

         begin

            -- Test Control: Set the indicator in the message to show it has

            -- passed through the Distributor object

            Transaction.TC_thru_Dist := true;

            -- Pass this transaction on to the appropriate computation

            -- task

            case Transaction.Code is

               when Credit =>

                  requeue Credit_Computation.Input;

               when Debit =>

                  requeue Debit_Computation.Input;

            end case;

         end Input;

      end Distributor;

      -- Assemble messages received from an external source

      --   Creates a message task for each. The message tasks remain extant

      --   for the life of the messages in the system.

      --   NOTE:

      --   The Line Driver task would normally be designed to loop continuously

      --   creating the messages as input is received.  Simulate this

      --   but limit it to two dummy messages for this test and allow it

      --   to terminate at that point

      --

      task body Line_Driver is

         Current_ID : integer := 1;

         TC_Last_was_for_credit : Boolean := false;

         procedure Build_Credit_Record

                          ( Next_Transaction : acc_Transaction_Record ) is

            Dummy_Account : constant integer := 100;

         begin

               Next_Transaction.ID := Current_ID;

               Next_Transaction.Code := Credit;

               Next_Transaction.Account_Number := Dummy_Account;

               Current_ID := Current_ID + 1;

         end Build_Credit_Record;

         procedure Build_Debit_Record

                          ( Next_Transaction : acc_Transaction_Record ) is

            Dummy_Account : constant integer := 200;

         begin

               Next_Transaction.ID := Current_ID;

               Next_Transaction.Code := Debit;

               Next_Transaction.Account_Number := Dummy_Account;

               Current_ID := Current_ID + 1;

         end Build_Debit_Record;

      begin

         accept Start;      -- Wait for trigger from Main

         for i in 1..2 loop  -- arbitrarily limit to two messages for the test

            declare

               -- Create a task for the next message

               Next_Message_Task : acc_Message_Task := new Message_Task;

               -- Create a record for it

               Next_Transaction : acc_Transaction_Record

                                                    := new Transaction_Record;

            begin

               if TC_Last_was_for_credit then

                  Build_Debit_Record ( Next_Transaction );

               else

                  Build_Credit_Record( Next_Transaction );

                  TC_Last_was_for_credit := true;

               end if;

               Next_Message_Task.Accept_Transaction ( Next_Transaction );

            end;   -- declare

         end loop;

      exception

         when others =>

            Report.Failed ("Unexpected exception in Line_Driver");

      end Line_Driver;

      task body Message_Task is

         TC_Original_Transaction_Code : Transaction_Code;

         This_Transaction : acc_Transaction_Record := new Transaction_Record;

      begin

         accept Accept_Transaction

                            (In_Transaction : acc_Transaction_Record) do

            This_Transaction.all := In_Transaction.all;

         end Accept_Transaction;

         -- Note the original code to ensure correct return

         TC_Original_Transaction_Code := This_Transaction.Code;

         -- Queue up on Distributor's Input queue

         Distributor.Input ( This_Transaction );

         -- This task will now wait for the requeued rendezvous

         -- to complete before proceeding

         -- After the required computations have been performed

         -- return the Transaction_Record appropriately (probably to an output

         -- line driver)

         null;            -- stub

         -- The following is all Test Control Code

         -- Check that the return values are as expected

         if TC_Original_Transaction_Code /= This_Transaction.Code then

            -- Incorrect rendezvous

            Report.Failed ("Message Task: Incorrect code returned");

         end if;

         if This_Transaction.Code = Credit then

            if This_Transaction.Return_Value     /= Credit_Return or

               This_Transaction.TC_Message_Count /= 1             or

               not This_Transaction.TC_thru_Dist       then

                  Report.Failed ("Expected path not traversed");

            end if;

         else

            if This_Transaction.Return_Value  /= Debit_Return or

               This_Transaction.TC_Message_Count /= 1         or

               not This_Transaction.TC_thru_Dist       then

                  Report.Failed ("Expected path not traversed");

            end if;

         end if;

      exception

         when others =>

            Report.Failed ("Unexpected exception in Message_Task");

      end Message_Task;

      -- Computation task.

      --   Note:  After the computation is performed in this task and the

      --          accept body is completed the rendezvous in the original

      --          message task is completed.

      --

      task body Credit_Computation is

         Message_Count   : integer := 0;

      begin

         loop

            select

               when  Time_Lock.Credit_enabled =>

               accept Input ( Transaction : acc_Transaction_Record) do

                  -- Perform the computations required for this transaction

                  null;      -- stub

                  -- For the test:

                  if not Transaction.TC_thru_Dist then

                     Report.Failed

                          ("Credit Task: Wrong queue, Distributor bypassed");

                  end if;

                  if Transaction.code /= Credit then

                     Report.Failed

                       ("Credit Task: Requeue delivered to the wrong queue");

                  end if;

                  -- for the test plug a known value and count

                  Transaction.Return_Value := Credit_Return;

                  -- one, and only one message should pass through

                  Message_Count := Message_Count + 1;

                  Transaction.TC_Message_Count := Message_Count;

               end Input;

               exit;  -- one message is enough

            else

               delay ImpDef.Clear_Ready_Queue;  -- poll

            end select;

         end loop;

      exception

         when others =>

            Report.Failed ("Unexpected exception in Credit_Computation");

      end Credit_Computation;

      -- Computation task.

      --   Note:  After the computation is performed in this task and the

      --          accept body is completed the rendezvous in the original

      --          message task is completed.

      --

      task body Debit_Computation is

         Message_Count   : integer := 0;

      begin

         loop

            select

               accept Input (Transaction : acc_Transaction_Record) do

                  -- Perform the computations required for this message

                  null;      -- stub

                  -- For the test:

                  if not Transaction.TC_thru_Dist then

                     Report.Failed

                            ("Debit Task: Wrong queue, Distributor bypassed");

                  end if;

                  if Transaction.code /= Debit then

                     Report.Failed

                         ("Debit Task: Requeue delivered to the wrong queue");

                  end if;

                  -- for the test plug a known value and count

                  Transaction.Return_Value := Debit_Return;

                  -- one, and only one, message should pass through

                  Message_Count := Message_Count + 1;

                  Transaction.TC_Message_Count := Message_Count;

                  -- for the test: once we have completed the only Debit

                  -- message release the Credit Messages which are queued

                  -- on the Credit Input queue

                  Time_Lock.Credit_Start;

               end Input;

            or

               terminate;

            end select;

         end loop;

      exception

         when others =>

            Report.Failed ("Unexpected exception in Debit_Computation");

      end Debit_Computation;

   begin -- declare block

      Line_Driver.Start;

   end;  -- test encapsulation

   Report.Result;

end C954024;