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-- C954024.A
--
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--     F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained 
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--                                    DISCLAIMER
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--     DISCLOSED ARE AS IS.  THE GOVERNMENT MAKES NO EXPRESS OR IMPLIED 
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--     OR DISCLOSED, OR THE OWNERSHIP, MERCHANTABILITY, OR FITNESS FOR A
--     PARTICULAR PURPOSE OF SAID MATERIAL.
--*
--
-- 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;