------------------------------------------------------------------------------
--                                                                          --
--                            GLADE COMPONENTS                              --
--                                                                          --
--                           S Y S T E M . R P C                            --
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--         Copyright (C) 1996-2020 Free Software Foundation, Inc.           --
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------------------------------------------------------------------------------

with Ada.Streams;

with System.Garlic.Streams;
with System.Garlic.Types;

package System.RPC is

   type Partition_ID is
     range System.Garlic.Types.Null_Partition_ID ..
       System.Garlic.Types.Last_Partition_ID;

   Communication_Error : exception;

   type Params_Stream_Type
     (Initial_Size : Ada.Streams.Stream_Element_Count) is new
       Ada.Streams.Root_Stream_Type with private;

   procedure Read
     (Stream : in out Params_Stream_Type;
      Item   : out Ada.Streams.Stream_Element_Array;
      Last   : out Ada.Streams.Stream_Element_Offset);

   procedure Write
     (Stream : in out Params_Stream_Type;
      Item   : Ada.Streams.Stream_Element_Array);

   procedure Do_RPC
     (Partition  : Partition_ID;
      Params     : access Params_Stream_Type;
      Result     : access Params_Stream_Type);
   --  Synchronous call

   procedure Do_APC
     (Partition  : Partition_ID;
      Params     : access Params_Stream_Type);
   --  Asynchronous call

   type RPC_Receiver is
     access procedure
       (Params     : access Params_Stream_Type;
        Result     : access Params_Stream_Type);
   --  Handled used for incoming RPC

   procedure Establish_RPC_Receiver (
      Partition : Partition_ID;
      Receiver  : RPC_Receiver);

private

   pragma Inline (Read);
   pragma Inline (Write);

   type Params_Stream_Type
     (Initial_Size : Ada.Streams.Stream_Element_Count)
   is new Ada.Streams.Root_Stream_Type with record
        X : aliased System.Garlic.Streams.Params_Stream_Type (Initial_Size);
   end record;

   type Session_Type is mod 2 ** 8;
   No_Session : constant Session_Type := Session_Type'First;

   procedure Allocate
     (Session   : out Session_Type;
      Partition : Partition_ID);

   procedure Deallocate
     (Session   : Session_Type);

   type RPC_Opcode is (RPC_Query,
                       RPC_Reply,
                       Abortion_Query,
                       Abortion_Reply,
                       APC_Query);
   --  Type of operation

   type RPC_Header (Kind : RPC_Opcode) is record
      case Kind is
         when RPC_Query      |
              RPC_Reply      |
              Abortion_Query |
              Abortion_Reply =>
            Session : Session_Type;
         when APC_Query      =>
            null;
      end case;
   end record;

   procedure Insert_RPC_Header
     (Params : access System.Garlic.Streams.Params_Stream_Type;
      Header : RPC_Header);
   --  Add a RPC_Header in front of Params

   procedure When_Established;
   --  Wait for partition to be established

   type Allocate_Task_Procedure is access procedure
     (Partition : System.Garlic.Types.Partition_ID;
      Session   : System.RPC.Session_Type;
      --  Stamp     : System.Garlic.Types.Stamp_Type;
      Params    : System.Garlic.Streams.Params_Stream_Access;
      Async     : Boolean);

   type Abort_Task_Procedure is access procedure
     (Partition : System.Garlic.Types.Partition_ID;
      Session   : System.RPC.Session_Type);

   type Parameterless_Procedure is access procedure;

   procedure Register_Task_Pool
     (Allocate_Task : Allocate_Task_Procedure;
      Abort_Task    : Abort_Task_Procedure;
      Initialize    : Parameterless_Procedure;
      Shutdown      : Parameterless_Procedure);

   procedure Finalize
     (Partition : System.Garlic.Types.Partition_ID;
      Waiting   : Boolean;
      Session   : Session_Type);
   --  Handle abortion from Do_RPC

end System.RPC;
