c954023.a

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-- C954023.A
--
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--
-- OBJECTIVE:
--     Check that a requeue within a protected entry to a family of entries 
--     in a different protected object is queued correctly
--                      Call with parameters
--                      Requeue with abort
--
-- TEST DESCRIPTION: 
--      One transaction is sent through to check the paths.  After processing
--      this, the Credit task sets the "overloaded" indicator.  Once this
--      indicator is set the Distributor (a protected object) queues lower
--      priority transactions on a family of queues (Wait_for_Underload) in
--      another protected object using a requeue.  The Distributor still
--      delivers high priority transactions. After two more high priority
--      transactions have been processed by the Credit task the artificial
--      test code clears the overload condition to the threshold level that
--      allows only the items on the Medium priority queue of the family to be
--      released.  When these have been processed and checked the test code
--      then lowers the priority threshold once again, allowing the Low
--      priority items from the last queue in the family to be released,
--      processed and checked. Note: the High priority queue in the family is 
--      not used.   
--     
--      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 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
--
--!

with Report;
with ImpDef;
         
procedure C954023 is

   -- Artificial: number of messages required for this test
   subtype TC_Trans_Range is integer range 1..8;

   TC_Credit_Messages_Expected  : constant integer 
                                          := TC_Trans_Range'Last - 1;

   TC_Debit_Message_Complete    : Boolean := false;


   -- Mechanism for handshaking between tasks
   protected TC_PO is
      procedure Increment_Tasks_Completed_Count;
      function  Tasks_Completed_Count return integer;
      function  First_Message_Has_Arrived return Boolean;
      procedure  Set_First_Message_Has_Arrived;
   private
      Number_Complete : integer := 0;
         Message_Arrived_Flag  : Boolean := false;
   end TC_PO;
   -- 
   protected body TC_PO is
      procedure Increment_Tasks_Completed_Count is
      begin
         Number_Complete := Number_Complete + 1;
      end Increment_Tasks_Completed_Count;
  
      function Tasks_Completed_Count return integer is
      begin
         return Number_Complete;
      end Tasks_Completed_Count;

      function  First_Message_Has_Arrived return Boolean is
         begin
            return Message_Arrived_Flag;
         end First_Message_Has_Arrived;

      procedure  Set_First_Message_Has_Arrived is
         begin
            Message_Arrived_Flag := true;
      end Set_First_Message_Has_Arrived;

   end TC_PO;

begin
   
   Report.Test ("C954023", "Requeue from within a protected object" &
                      " to a family of entries in another protected object");

 
   declare -- encapsulate the test
   
      -- Arbitrary test values
      Credit_Return : constant := 1;
      Debit_Return  : constant := 2;

      type Transaction_Code is (Credit, Debit);
      type App_Priority     is (Low, Medium, High);
      type Priority_Block   is array (App_Priority) of Boolean;

      type Transaction_Record;
      type acc_Transaction_Record is access Transaction_Record;
      type Transaction_Record is 
         record
            ID               : integer := 0;
            Code             : Transaction_Code := Debit;
            Priority         : App_Priority := High;
            Account_Number   : integer := 0;
            Stock_Number     : integer := 0;
            Quantity         : integer := 0;
            Return_Value     : integer := 0;
            TC_Message_Count : integer := 0;
            TC_Thru_Distrib  : 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;
   
      protected Distributor is
         procedure Set_Credit_Overloaded;
         procedure Clear_Overload_to_Medium;
         procedure Clear_Overload_to_Low;
         entry     Input (Transaction : acc_Transaction_Record);
      private
         Credit_Overloaded : Boolean := false;
      end Distributor;
   
      protected Hold is
         procedure Release_Medium;
         procedure Release_Low;
         -- Family of entry queues indexed by App_Priority
         entry Wait_for_Underload (App_Priority)
                                     (Transaction : acc_Transaction_Record);
      private
         Release : Priority_Block := (others => false);
      end Hold;
   
      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;
   
      --
      -- Dispose each input Transaction_Record to the appropriate
      -- computation tasks
      --
      protected body Distributor is
   
         procedure Set_Credit_Overloaded is
         begin
            Credit_Overloaded := true;
         end Set_Credit_Overloaded;
   
         procedure Clear_Overload_to_Medium is
         begin
            Credit_Overloaded := false;
            Hold.Release_Medium;       -- Release all held messages on Medium
                                       -- priority queue
         end Clear_Overload_to_Medium;
     
         procedure Clear_Overload_to_Low is
         begin
            Credit_Overloaded := false;
            Hold.Release_Low;          -- Release all held messages on Low
                                       -- priority queue
         end Clear_Overload_to_Low;
     
   
   
         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_Distrib := true;
    
            -- Pass this transaction on to the appropriate computation
            -- task but temporarily hold low-priority transactions under
            -- overload conditions
            case Transaction.Code is
               when Credit =>
                  if Credit_Overloaded and Transaction.Priority /= High then
                     -- use the appropriate queue in the family 
                     requeue Hold.Wait_for_Underload(Transaction.Priority)
                                                         with abort;
                  else
                     requeue Credit_Computation.Input with abort;
                 end if;
               when Debit =>
                 requeue Debit_Computation.Input with abort;
            end case;
         end Input;
      end Distributor;
   
   
      -- Low priority Message tasks are held on the Wait_for_Underload queue
      -- while the Credit computation system is overloaded.  Once the Credit
      -- system reached underload send all queued messages immediately
      --
      protected body Hold is
         
         -- Once these are executed the barrier conditions for the entries
         -- are evaluated 
         procedure Release_Medium is
         begin 
            Release(Medium) := true;
         end Release_Medium;
         --
         procedure Release_Low is
         begin 
            Release(Low) := true;
         end Release_Low;
   
         -- This is a family of entry queues indexed by App_Priority
         entry Wait_for_Underload  (for AP in App_Priority)
                                   (Transaction : acc_Transaction_Record)
                                                when Release(AP) is
         begin
            requeue Credit_Computation.Input with abort;
            if Wait_for_Underload(AP)'count = 0 then
               -- Queue is purged.  Set up to hold next batch
               Release(AP) := false;
            end if; 
         end Wait_for_Underload;
   
      end Hold;
      
   
   
   
      -- 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.
      --      The Line Driver task would normally be designed to loop 
      --      creating the messages as input is received.  Simulate this 
      --      but limit it to the required number of dummy messages needed for
      --      this test and allow it to terminate at that point.  Artificially
      --      cycle the generation of High medium and Low priority Credit 
      --      transactions for this test. Send out one final Debit message
      --
      task body Line_Driver is