-- C954021.A
--
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--     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.
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--     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 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
         return Number_Complete;
      end Count;
   end TC_Tasks_Completed;


   -- 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 continuously
   --      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
   --      alternate High and Low priority Credit transactions for this test.
   --
   task body Line_Driver is
      Current_ID       : integer := 1;
      Current_Priority : Transaction_Priority := High;      

      -- Artificial: number of messages required for this test
      type TC_Trans_Range is range 1..6;

      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.Priority := Current_Priority;

            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 Transaction_Numb in TC_Trans_Range loop  -- TC: limit the loop
         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 Transaction_Numb = TC_Trans_Range'first then
               -- Send the first Credit message
               Build_Credit_Record ( Next_Transaction );
               Next_Message_Task.Accept_Transaction ( Next_Transaction );  
               -- TC: Wait until the first message has been received by the
               -- Credit task and it has set the Overload indicator for the 
               -- Distributor
               while not TC_Handshake.First_Message_Arrived loop
                  delay ImpDef.Minimum_Task_Switch;   
               end loop;
            elsif Transaction_Numb = TC_Trans_Range'last then
               -- For this test send the last transaction to the Debit task
               -- to improve the mix
               Build_Debit_Record( Next_Transaction );
               Next_Message_Task.Accept_Transaction ( Next_Transaction );  
            else
               -- TC: Alternate high and low priority transactions
               if Current_Priority = High then
                  Current_Priority := Low;
               else
                  Current_Priority := High;
               end if;
               Build_Credit_Record( Next_Transaction );
               Next_Message_Task.Accept_Transaction ( Next_Transaction );  
            end if;
         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
      
      -- For the test 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
         not This_Transaction.TC_thru_Dist                    then
            Report.Failed ("Expected path not traversed - Credit");
         end if;
         TC_Tasks_Completed.Increment;
      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 - Debit");
         end if;
         TC_Debit_Message_Complete.Set_True;
      end if;

   exception
      when others => 
         Report.Failed ("Unexpected exception in Message_Task");
   end Message_Task;


   -- Computation task.  After the computation is performed the rendezvous
   -- in the original message task is completed.                              
   task body Credit_Computation is

      Message_Count   : integer := 0;
      
   begin
      loop
         select 
            accept Input ( Transaction : acc_Transaction_Record) do
               if Distributor.Credit_is_Overloaded
                                    and Transaction.Priority = Low  then 
                  -- We should not be getting any Low Priority messages. They
                  -- should be waiting on the Hold.Wait_for_Underload 
                  -- queue
                  Report.Failed 
                     ("Credit Task: Low priority transaction during overload");
               end if;
               -- 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;

               -- The following is all Test Control code:
               Transaction.Return_Value := Credit_Return;
               Message_Count := Message_Count + 1;
               --
               -- Now take special action depending on which Message
               if Message_Count = 1 then 
                  -- After the first message :
                  Distributor.Set_Credit_Overloaded;
                  -- Now flag the Line_Driver that the second and subsequent
                  -- messages may now be sent
                  TC_Handshake.Set;
               end if;
               if Message_Count = 3 then
                  -- The two high priority transactions created subsequent
                  -- to the overload have now been processed
                  Distributor.Clear_Credit_Overloaded;
               end if;
            end Input;            
         or
            terminate;
         end select;
      end loop;
   exception
      when others => 
         Report.Failed ("Unexpected exception in Credit_Computation");
   end Credit_Computation;


   -- Computation task.  After the computation is performed 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;
            end Input;            
         or
            terminate;
         end select;
      end loop;
   exception
      when others => 
         Report.Failed ("Unexpected exception in Debit_Computation");
   end Debit_Computation;


begin 
   Report.Test ("C954021", "Requeue from one entry body to an entry in" &
                                       " another protected object");

   Line_Driver.Start;  -- Start the test


   -- Ensure that the message tasks have completed before reporting result
   while (TC_Tasks_Completed.Count < TC_Credit_Messages_Expected) 
         and not TC_Debit_Message_Complete.Value loop
      delay ImpDef.Minimum_Task_Switch;   
   end loop;

   Report.Result;

end C954021;