c954021.a

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-- C954021.A
--
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--     F08630-91-C-0015, and DCA100-97-D-0025, the U.S. Government obtained 
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--     released technical data and computer software in whole or in part, in 
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--                                    DISCLAIMER
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--     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 a requeue within a protected entry to an entry in a
--     different protected object is queued correctly.
--
-- 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 low
--      priority transactions on a Wait_for_Underload queue in another
--      protected object using a requeue. The Distributor still delivers high
--      priority transactions.  After two high priority transactions have been
--      processed by the Credit task it clears the overload condition.  The
--      low priority transactions should now be delivered. 
--     
--      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
--      26 Nov 95   SAIC    Fixed shared global variable for ACVC 2.0.1
--
--!

with Report;
with ImpDef;
         
procedure C954021 is
 
   -- Arbitrary test values
   Credit_Return : constant := 1;
   Debit_Return  : constant := 2;


   -- Mechanism to count the number of Credit Message tasks completed
   protected TC_Tasks_Completed is
      procedure Increment;
      function  Count return integer;
   private
      Number_Complete : integer := 0;
   end TC_Tasks_Completed;
   
   
   TC_Credit_Messages_Expected  : constant integer := 5;

   protected TC_Handshake is
      procedure Set;
      function First_Message_Arrived return Boolean;
   private
      Arrived_Flag : Boolean := false;
   end TC_Handshake;

   -- Handshaking mechanism between the Line Driver and the Credit task
   -- 
   protected body TC_Handshake is
      --
      procedure Set is
      begin 
         Arrived_Flag := true;
      end Set;
      --
      function First_Message_Arrived return Boolean is
      begin
         return Arrived_Flag;
      end First_Message_Arrived;
      -- 
   end TC_Handshake;


   protected type Shared_Boolean (Initial_Value : Boolean := False) is
      procedure Set_True;
      procedure Set_False;
      function  Value return Boolean;
   private
      Current_Value : Boolean := Initial_Value;
   end Shared_Boolean;

   protected body Shared_Boolean is
      procedure Set_True is
      begin
         Current_Value := True;
      end Set_True;

      procedure Set_False is
      begin
         Current_Value := False;
      end Set_False;

      function Value return Boolean is
      begin
         return Current_Value;
      end Value;
   end Shared_Boolean;
 
   TC_Debit_Message_Complete    : Shared_Boolean (False);

   type Transaction_Code is (Credit, Debit);
   type Transaction_Priority is (High, Low);

   type Transaction_Record;
   type acc_Transaction_Record is access Transaction_Record;
   type Transaction_Record is 
      record
         ID               : integer := 0;
         Code             : Transaction_Code := Debit;
         Priority         : Transaction_Priority := High;
         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;

   protected Distributor is
      procedure Set_Credit_Overloaded;
      procedure Clear_Credit_Overloaded;
      function  Credit_is_Overloaded return Boolean;
      entry     Input (Transaction : acc_Transaction_Record);
   private
      Credit_Overloaded : Boolean := false;
   end Distributor;

   protected Hold is
      procedure Underloaded;
      entry Wait_for_Underload (Transaction : acc_Transaction_Record);
   private
      Release_All : Boolean := 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_Credit_Overloaded is
      begin
         Credit_Overloaded := false;
         Hold.Underloaded;       -- Release all held messages
      end Clear_Credit_Overloaded;
  
      function  Credit_is_Overloaded return Boolean is
      begin
         return Credit_Overloaded;
      end Credit_is_Overloaded;


      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 but temporarily hold low-priority transactions under
         -- overload conditions
         case Transaction.Code is
            when Credit =>
               if Credit_Overloaded and Transaction.Priority = Low then
                  requeue Hold.Wait_for_Underload 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 this is executed the barrier condition for the entry is 
      -- evaluated 
      procedure Underloaded is
      begin 
         Release_All := true;
      end Underloaded;

      entry Wait_for_Underload (Transaction : acc_Transaction_Record)
                                                     when Release_All is
      begin
         requeue Credit_Computation.Input with abort;
         if Wait_for_Underload'count = 0 then
            -- Queue is purged.  Set up to hold next batch
            Release_All := false;
         end if; 
      end Wait_for_Underload;

   end Hold;
   
   -- Mechanism to count the number of Message tasks completed (Credit)
   protected body TC_Tasks_Completed is
      procedure Increment is
      begin
         Number_Complete := Number_Complete + 1;
      end Increment;

      function Count return integer is
      begin