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-- C954012.A

--

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--

-- OBJECTIVE:

--     Check a requeue within an accept body to another entry in the same task

--     Specifically, check a call with parameters and a 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 queues low priority transactions

--      on a Wait_for_Underload queue in the same task 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

--      25 Nov 95   SAIC    Fixed shared global variable problem for

--                          ACVC 2.0.1

--      14 Mar 03   RLB     Fixed a race condition and an incorrect termination

--                          condition in the test.

--!

with Report;

with ImpDef;

with Ada.Calendar;

procedure C954012 is

   function "=" (X,Y: Ada.Calendar.Time) return Boolean

                                                   renames Ada.Calendar."=";

   -- Arbitrary test values

   Credit_Return : constant := 1;

   Debit_Return  : constant := 2;

   -- This is used as an "initializing" time for the messages as they are

   -- created.  As they pass through the Distributor they get a time_stamp

   -- of the current time. An arbitrary base time is chosen.

   --    TC: this fact is used, incidentally, to check that the messages have,

   --    indeed, passed through the Distributor as expected.

   --

   Base_Time : Ada.Calendar.Time := Ada.Calendar.Time_of(1959,3,9);

   -- 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;

   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);

   -- Handshaking mechanism between the Line Driver and the Credit task

   TC_First_Message_Has_Arrived : Shared_Boolean (False);

   Credit_Overloaded : Shared_Boolean (False);

   TC_Credit_Messages_Expected  : constant integer := 5;

   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;

         Message_Count    : integer := 0;          -- for test

         Time_Stamp       : Ada.Calendar.Time := Base_Time;

      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 Distributor is

      entry Input (Transaction : acc_Transaction_Record);

      entry Wait_for_Underload (Transaction : acc_Transaction_Record);

      entry TC_Credit_OK;

   end Distributor;

   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;

   -- 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_First_Message_Has_Arrived.Value 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;

      -- TC: Wait for Credit_Overloaded to be cleared, then insure that the

      -- Distributor has evalated all tasks. Otherwise, some tasks may never

      -- be evaluated.

      while Credit_Overloaded.Value loop

        delay ImpDef.Minimum_Task_Switch;

      end loop;

      Distributor.TC_Credit_OK;

   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

            This_Transaction.Time_Stamp     = Base_Time     then

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

         end if;

            TC_Tasks_Completed.Increment;

      else

         if This_Transaction.Return_Value  /= Debit_Return or

            This_Transaction.Message_Count /= 1             or

            This_Transaction.Time_Stamp     = Base_Time     then

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

         end if;

         TC_Debit_Message_Complete.Set_True;

      end if;

   exception

      when others =>

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

   end Message_Task;

   -- Dispose each input Transaction_Record to the appropriate

   -- computation tasks

   --

   task body Distributor is

   begin

      loop

         select

            accept Input (Transaction : acc_Transaction_Record) do

               -- Time_Stamp the messages with the current time

               --    TC: Used, incidentally, by the test to check that the

               --    message did pass through the Distributor Task

               Transaction.Time_Stamp := Ada.Calendar.Clock;

               -- 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.Value and

                        Transaction.Priority = Low then

                        requeue 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;

         or

            when not Credit_Overloaded.Value =>

            accept Wait_for_Underload (Transaction : acc_Transaction_Record) do

               requeue Credit_Computation.Input with abort;

            end Wait_for_Underload;

         or

            accept TC_Credit_OK;

               -- We need this to insure that we evaluate the guards at least

               -- once when Credit_Overloaded is False. Otherwise, tasks

               -- could stay queued on Wait_for_Underload forever (starvation).

         or

            terminate;

         end select;

      end loop;

   exception

      when others =>

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

   end Distributor;

   -- 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 Credit_Overloaded.Value and

                  Transaction.Priority = Low then

                  -- We should not be getting any Low Priority messages. They

                  -- should be waiting on the Distributor's 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 Transaction.Time_Stamp = Base_Time 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 :

                  Credit_Overloaded.Set_True;

                  -- Now flag the Line_Driver that the second and subsequent

                  -- messages may now be sent

                  TC_First_Message_Has_Arrived.Set_True;

               end if;

               if Message_Count = 3 then

                  -- The two high priority transactions created subsequent

                  -- to the overload have now been processed

                  Credit_Overloaded.Set_False;

               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 Transaction.Time_Stamp = Base_Time 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.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 -- c954012

   Report.Test ("C954012", "Requeue within an accept body" &

                           " to another entry in the same task");

   Line_Driver.Start;  -- Start the test

   -- Ensure that the message tasks complete before reporting the result

   while (TC_Tasks_Completed.Count < TC_Credit_Messages_Expected)

         or (not TC_Debit_Message_Complete.Value) loop

      delay ImpDef.Minimum_Task_Switch;

   end loop;

   Report.Result;

end C954012;