------------------------------------------------------------------------------ -- -- -- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS -- -- -- -- SYSTEM.TASKING.PROTECTED_OBJECTS.ENTRIES -- -- -- -- S p e c -- -- -- -- -- -- Copyright (C) 1992-2001, Free Software Foundation, Inc. -- -- -- -- GNARL is free software; you can redistribute it and/or modify it under -- -- terms of the GNU General Public License as published by the Free Soft- -- -- ware Foundation; either version 2, or (at your option) any later ver- -- -- sion. GNARL is distributed in the hope that it will be useful, but WITH- -- -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License -- -- for more details. You should have received a copy of the GNU General -- -- Public License distributed with GNARL; see file COPYING. If not, write -- -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, -- -- MA 02111-1307, USA. -- -- -- -- As a special exception, if other files instantiate generics from this -- -- unit, or you link this unit with other files to produce an executable, -- -- this unit does not by itself cause the resulting executable to be -- -- covered by the GNU General Public License. This exception does not -- -- however invalidate any other reasons why the executable file might be -- -- covered by the GNU Public License. -- -- -- -- GNARL was developed by the GNARL team at Florida State University. -- -- Extensive contributions were provided by Ada Core Technologies Inc. -- -- -- ------------------------------------------------------------------------------ -- This package contains all the simple primitives related to -- Protected_Objects with entries (i.e init, lock, unlock). -- The handling of protected objects with no entries is done in -- System.Tasking.Protected_Objects, the complex routines for protected -- objects with entries in System.Tasking.Protected_Objects.Operations. -- The split between Entries and Operations is needed to break circular -- dependencies inside the run time. -- Note: the compiler generates direct calls to this interface, via Rtsfind. -- Any changes to this interface may require corresponding compiler changes. with Ada.Finalization; -- used for Limited_Controlled with Unchecked_Conversion; package System.Tasking.Protected_Objects.Entries is pragma Elaborate_Body; subtype Positive_Protected_Entry_Index is Protected_Entry_Index range 1 .. Protected_Entry_Index'Last; type Find_Body_Index_Access is access function (O : System.Address; E : Protected_Entry_Index) return Protected_Entry_Index; type Protected_Entry_Body_Array is array (Positive_Protected_Entry_Index range <>) of Entry_Body; -- This is an array of the executable code for all entry bodies of -- a protected type. type Protected_Entry_Body_Access is access all Protected_Entry_Body_Array; type Protected_Entry_Queue_Array is array (Protected_Entry_Index range <>) of Entry_Queue; -- This type contains the GNARL state of a protected object. The -- application-defined portion of the state (i.e. private objects) -- is maintained by the compiler-generated code. -- note that there is a simplified version of this type declared in -- System.Tasking.PO_Simple that handle the simple case (no entries). type Protection_Entries (Num_Entries : Protected_Entry_Index) is new Ada.Finalization.Limited_Controlled with record L : aliased Task_Primitives.Lock; -- The underlying lock associated with a Protection_Entries. -- Note that you should never (un)lock Object.L directly, but instead -- use Lock_Entries/Unlock_Entries. Compiler_Info : System.Address; Call_In_Progress : Entry_Call_Link; Ceiling : System.Any_Priority; Old_Base_Priority : System.Any_Priority; Pending_Action : Boolean; -- Flag indicating that priority has been dipped temporarily -- in order to avoid violating the priority ceiling of the lock -- associated with this protected object, in Lock_Server. -- The flag tells Unlock_Server or Unlock_And_Update_Server to -- restore the old priority to Old_Base_Priority. This is needed -- because of situations (bad language design?) where one -- needs to lock a PO but to do so would violate the priority -- ceiling. For example, this can happen when an entry call -- has been requeued to a lower-priority object, and the caller -- then tries to cancel the call while its own priority is higher -- than the ceiling of the new PO. Finalized : Boolean := False; -- Set to True by Finalize to make this routine idempotent. Entry_Bodies : Protected_Entry_Body_Access; -- The following function maps the entry index in a call (which denotes -- the queue to the proper entry) into the body of the entry. Find_Body_Index : Find_Body_Index_Access; Entry_Queues : Protected_Entry_Queue_Array (1 .. Num_Entries); end record; pragma Volatile (Protection_Entries); -- No default initial values for this type, since call records -- will need to be re-initialized before every use. type Protection_Entries_Access is access all Protection_Entries'Class; -- See comments in s-tassta.adb about the implicit call to Current_Master -- generated by this declaration. function To_Protection_Entries is new Unchecked_Conversion (Protection_Access, Protection_Entries_Access); function To_Address is new Unchecked_Conversion (Protection_Entries_Access, System.Address); function To_Protection is new Unchecked_Conversion (System.Address, Protection_Entries_Access); function Has_Interrupt_Or_Attach_Handler (Object : Protection_Entries_Access) return Boolean; -- Returns True if an Interrupt_Handler or Attach_Handler pragma applies -- to the protected object. That is to say this primitive returns False for -- Protection, but is overriden to return True when interrupt handlers are -- declared so the check required by C.3.1(11) can be implemented in -- System.Tasking.Protected_Objects.Initialize_Protection. procedure Initialize_Protection_Entries (Object : Protection_Entries_Access; Ceiling_Priority : Integer; Compiler_Info : System.Address; Entry_Bodies : Protected_Entry_Body_Access; Find_Body_Index : Find_Body_Index_Access); -- Initialize the Object parameter so that it can be used by the runtime -- to keep track of the runtime state of a protected object. procedure Lock_Entries (Object : Protection_Entries_Access); -- Lock a protected object for write access. Upon return, the caller -- owns the lock to this object, and no other call to Lock or -- Lock_Read_Only with the same argument will return until the -- corresponding call to Unlock has been made by the caller. -- Program_Error is raised in case of ceiling violation. procedure Lock_Entries (Object : Protection_Entries_Access; Ceiling_Violation : out Boolean); -- Same as above, but return the ceiling violation status instead of -- raising Program_Error. procedure Lock_Read_Only_Entries (Object : Protection_Entries_Access); -- Lock a protected object for read access. Upon return, the caller -- owns the lock for read access, and no other calls to Lock with the -- same argument will return until the corresponding call to Unlock -- has been made by the caller. Other calls to Lock_Read_Only may (but -- need not) return before the call to Unlock, and the corresponding -- callers will also own the lock for read access. -- -- Note: we are not currently using this interface, it is provided -- for possible future use. At the current time, everyone uses Lock -- for both read and write locks. procedure Unlock_Entries (Object : Protection_Entries_Access); -- Relinquish ownership of the lock for the object represented by -- the Object parameter. If this ownership was for write access, or -- if it was for read access where there are no other read access -- locks outstanding, one (or more, in the case of Lock_Read_Only) -- of the tasks waiting on this lock (if any) will be given the -- lock and allowed to return from the Lock or Lock_Read_Only call. private procedure Finalize (Object : in out Protection_Entries); -- Clean up a Protection object; in particular, finalize the associated -- Lock object. end System.Tasking.Protected_Objects.Entries;