15.4.902  src/lib/src/lib/thread-kit/src/core-thread-kit/internal-threadkit-types.pkg

## internal-threadkit-types.pkg
## COPYRIGHT (c) 1989-1991 John H. Reppy

# Compiled by:
#     src/lib/std/standard.lib


# These are the concrete representations of the various threadkit types.
# These types are abstract (or not even visible) outside this library.


package internal_threadkit_types {

    # Threadkit queues --- see
    #
    #    src/lib/src/lib/thread-kit/src/core-thread-kit/threadkit-queue.pkg
    #    
    Threadkit_Queue(X)
        =
        THREADKIT_QUEUE  {
            front:  Ref(  List(X) ),
            rear:   Ref(  List(X) )
        };

    # Thread IDs --- see
    #
    #     src/lib/src/lib/thread-kit/src/core-thread-kit/thread.pkg
    #
    Thread
        =
        THREAD                                                  # Thread ids.
          { thread_id:          Int,                            # A unique ID. 
            name:               String,                         # Purely for display to humans.
            did_mail:           Ref( Bool ),                    # Set this whenever this thread does some concurrency operation. 

            exception_handler:  Ref( Exception -> Void ),       # Root-level exception handler hook.
            properties:         Ref(  List(  Exception ) ),     # Holds thread-local properties.

            dead:               Condition_Variable              # Set when the thread dies. 
          }

    # Transaction IDs are used to mark blocked
    # threads in the various waiting queues.
    #
    # They are "cancelled" when some other
    # mailop is selected.
    #
    also
    Transaction_Id
      = CANCELLED_TRANSACTION_ID
      |           TRANSACTION_ID  Thread

    # Condition variables --- see
    #     src/lib/src/lib/thread-kit/src/core-thread-kit/mailop.pkg
    # These are essentially Void-valued oneshot_maildrop instances,
    # and are used for various internal synchronization
    # conditions, e.g., nack mail_ops, I/O synchronization,
    # and thread termination:
    #
    also
    Condition_Variable
        =
        CONDITION_VARIABLE  Ref( Condition_Variable_State )

    also
    Condition_Variable_State
      = CVAR_UNSET   List { transaction_id:  Ref( Transaction_Id ),
                            clean_up:        Void -> Void,
                            fate:            fate::Fate( Void )
                          }
      | CVAR_SET  Int
      ;

    # Mail ops --- see
    #     src/lib/src/lib/thread-kit/src/core-thread-kit/mailop.pkg
    #
    Mailop_Status(X)
      #
      = MAILOP_READY
          { priority:   Int,
            do_it:      Void -> X                                               # Reppy calls this field doFn
          }

      | MAILOP_UNREADY
          { transaction_id:  Ref( Transaction_Id ),
            clean_up:        Void -> Void,
            next:            Void -> Void
          }
          ->
          X
      ;

    Base_Mailop(X)
        =
        Void -> Mailop_Status(X);

    Mailop(X)
      = BASE_MAILOPS  List( Base_Mailop(X) )
      | CHOOSE        List(      Mailop(X) )
      | GUARD         Void         -> Mailop(X)
      | WITH_NACK     Mailop(Void) -> Mailop(X)
      ;

    # Useful when debugging threadkit internals:
    #
    fun thread_to_string (THREAD { thread_id, ... } )
        =
        cat [ "[",
               number_string::pad_left '0' 6 (int::to_string thread_id),
              "]"
            ];

};


## COPYRIGHT (c) 1995 AT&T Bell Laboratories.
## Subsequent changes by Jeff Prothero Copyright (c) 2010-2012,
## released under Gnu Public Licence version 3.