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

package System.Garlic.Storages is

   pragma Elaborate_Body;

   type Shared_Data_Type is abstract
     new Ada.Streams.Root_Stream_Type with null record;

   type Shared_Data_Access is access all Shared_Data_Type'Class;

   type Request_Type is (Read, Write, Lock);

   --  Primitives of Shared_Data_Type

   procedure Create_Storage
     (Master   : in out Shared_Data_Type;
      Location : in     String;
      Storage  : out    Shared_Data_Access) is abstract;
   --  Provide the Master factory with a location and return another
   --  Storage factory initialized with the data from the location
   --  location. This factory is supposed to be used into the
   --  Create_Package routine.

   procedure Create_Package
     (Storage  : in out Shared_Data_Type;
      Pkg_Name : in     String;
      Pkg_Data : out    Shared_Data_Access) is abstract;
   --  Return a Pkg_Data factory which is supposed to be used in the
   --  Create_Variable routine. This intermediate layer between
   --  Create_Storage and Create_Variable is used to configure a
   --  shared passive unit on a storage.

   procedure Create_Variable
     (Pkg_Data : in out Shared_Data_Type;
      Var_Name : in     String;
      Var_Data : out    Shared_Data_Access) is abstract;
   --  Return a stream to use when any read or write operation is
   --  performed.

   procedure Initiate_Request
     (Var_Data : in out Shared_Data_Type;
      Request  : in     Request_Type;
      Success  : out    Boolean) is abstract;
   --  Initiate an operation on a variable. This routine can be thread
   --  blocking in order to serialize several concurrent requests and
   --  should be protected against abortion. Success returns whether
   --  the request can be performed on the variable. Typically, if
   --  there is no storage available on a read operation, Success is
   --  set to False. Any exception must be caught inside the
   --  routine. Note also that primitives Read and Write must catch
   --  all the potential exceptions.

   procedure Complete_Request
     (Var_Data : in out Shared_Data_Type) is abstract;
   --  Complete the request previously initiated by the routine above.

   --  Any storage implementation must provide an Initialize routine.
   --     procedure Initialize;
   --  This routine is supposed to elaborate the package body of the
   --  storage support implementation. It must include the
   --  registration of a master factory dedicated to the storage
   --  support. This must be done using register_storage.


   --  General services

   function  Lookup_Variable
     (Var_Name : in String)
     return Shared_Data_Access;

   function  Lookup_Storage
     (Storage_Name : in String)
     return Shared_Data_Access;

   procedure Register_Storage
     (Storage_Name : in String;
      Storage_Data : in Shared_Data_Access);
   --  Register a factory for a storage. This factory is used to
   --  produce another factory each time a shared passive package is
   --  registered. Multiple registrations are ignored. Call it at
   --  elaboration time.

   procedure Register_Package
     (Pkg_Name  : in String;
      Partition : in Types.Partition_ID);
   --  Register a shared passive package on a partition and create a
   --  factory to produce shared variables later on. Multiple
   --  registrations are ignored. Call it at elaboration time.

   procedure Register_Partition
     (Partition : in Types.Partition_ID;
      Location  : in String);
   --  Register a partition and its storage location (support and
   --  data). If the partition has already been registered, ignored
   --  this request. If not, create the factory to produce shared
   --  variables. Call it at elaboration time.

end System.Garlic.Storages;
