179 lines
8.2 KiB
Ada
179 lines
8.2 KiB
Ada
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------------------------------------------------------------------------------
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-- --
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-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
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-- --
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-- S Y S T E M . T A S K I N G . I N I T I A L I Z A T I O N --
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-- --
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-- S p e c --
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-- --
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-- Copyright (C) 1992-2014, Free Software Foundation, Inc. --
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-- --
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-- GNARL is free software; you can redistribute it and/or modify it under --
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-- terms of the GNU General Public License as published by the Free Soft- --
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-- ware Foundation; either version 3, or (at your option) any later ver- --
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-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE. --
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-- --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception, --
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-- version 3.1, as published by the Free Software Foundation. --
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-- --
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-- You should have received a copy of the GNU General Public License and --
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-- a copy of the GCC Runtime Library Exception along with this program; --
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-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
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-- <http://www.gnu.org/licenses/>. --
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-- --
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-- GNARL was developed by the GNARL team at Florida State University. --
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-- Extensive contributions were provided by Ada Core Technologies, Inc. --
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-- --
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------------------------------------------------------------------------------
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-- This package provides overall initialization of the tasking portion of the
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-- RTS. This package must be elaborated before any tasking features are used.
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package System.Tasking.Initialization is
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procedure Remove_From_All_Tasks_List (T : Task_Id);
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-- Remove T from All_Tasks_List. Call this function with RTS_Lock taken
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procedure Finalize_Attributes (T : Task_Id);
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-- Finalize all attributes from T. This is to be called just before the
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-- ATCB is deallocated. It relies on the caller holding T.L write-lock
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-- on entry.
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---------------------------------
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-- Tasking-Specific Soft Links --
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---------------------------------
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-------------------------
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-- Abort Defer/Undefer --
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-------------------------
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-- Defer_Abort defers the effects of low-level abort and priority change
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-- in the calling task until a matching Undefer_Abort call is executed.
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-- Undefer_Abort DOES MORE than just undo the effects of one call to
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-- Defer_Abort. It is the universal "polling point" for deferred
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-- processing, including the following:
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-- 1) base priority changes
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-- 2) abort/ATC
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-- Abort deferral MAY be nested (Self_ID.Deferral_Level is a count), but
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-- to avoid waste and undetected errors, it generally SHOULD NOT be
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-- nested. The symptom of over-deferring abort is that an exception may
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-- fail to be raised, or an abort may fail to take place.
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-- Therefore, there are two sets of the inlineable defer/undefer routines,
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-- which are the ones to be used inside GNARL. One set allows nesting. The
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-- other does not. People who maintain the GNARL should try to avoid using
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-- the nested versions, or at least look very critically at the places
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-- where they are used.
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-- In general, any GNARL call that is potentially blocking, or whose
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-- semantics require that it sometimes raise an exception, or that is
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-- required to be an abort completion point, must be made with abort
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-- Deferral_Level = 1.
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-- In general, non-blocking GNARL calls, which may be made from inside a
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-- protected action, are likely to need to allow nested abort deferral.
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-- With some critical exceptions (which are supposed to be documented),
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-- internal calls to the tasking runtime system assume abort is already
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-- deferred, and do not modify the deferral level.
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-- There is also a set of non-inlineable defer/undefer routines, for direct
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-- call from the compiler. These are not inlineable because they may need
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-- to be called via pointers ("soft links"). For the sake of efficiency,
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-- the version with Self_ID as parameter should used wherever possible.
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-- These are all nestable.
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-- Non-nestable inline versions
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procedure Defer_Abort (Self_ID : Task_Id);
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pragma Inline (Defer_Abort);
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procedure Undefer_Abort (Self_ID : Task_Id);
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pragma Inline (Undefer_Abort);
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-- Nestable inline versions
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procedure Defer_Abort_Nestable (Self_ID : Task_Id);
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pragma Inline (Defer_Abort_Nestable);
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procedure Undefer_Abort_Nestable (Self_ID : Task_Id);
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pragma Inline (Undefer_Abort_Nestable);
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procedure Do_Pending_Action (Self_ID : Task_Id);
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-- Only call with no locks, and when Self_ID.Pending_Action = True Perform
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-- necessary pending actions (e.g. abort, priority change). This procedure
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-- is usually called when needed as a result of calling Undefer_Abort,
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-- although in the case of e.g. No_Abort restriction, it can be necessary
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-- to force execution of pending actions.
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function Check_Abort_Status return Integer;
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-- Returns Boolean'Pos (True) iff abort signal should raise
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-- Standard'Abort_Signal. Only used by IRIX currently.
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--------------------------
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-- Change Base Priority --
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--------------------------
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procedure Change_Base_Priority (T : Task_Id);
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-- Change the base priority of T. Has to be called with the affected
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-- task's ATCB write-locked. May temporarily release the lock.
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----------------------
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-- Task Lock/Unlock --
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----------------------
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procedure Task_Lock (Self_ID : Task_Id);
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pragma Inline (Task_Lock);
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procedure Task_Unlock (Self_ID : Task_Id);
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pragma Inline (Task_Unlock);
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-- These are versions of Lock_Task and Unlock_Task created for use
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-- within the GNARL.
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procedure Final_Task_Unlock (Self_ID : Task_Id);
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-- This version is only for use in Terminate_Task, when the task is
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-- relinquishing further rights to its own ATCB. There is a very
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-- interesting potential race condition there, where the old task may run
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-- concurrently with a new task that is allocated the old tasks (now
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-- reused) ATCB. The critical thing here is to not make any reference to
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-- the ATCB after the lock is released. See also comments on
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-- Terminate_Task and Unlock.
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procedure Wakeup_Entry_Caller
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(Self_ID : Task_Id;
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Entry_Call : Entry_Call_Link;
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New_State : Entry_Call_State);
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pragma Inline (Wakeup_Entry_Caller);
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-- This is called at the end of service of an entry call, to abort the
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-- caller if he is in an abortable part, and to wake up the caller if he
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-- is on Entry_Caller_Sleep. Call it holding the lock of Entry_Call.Self.
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--
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-- Timed_Call or Simple_Call:
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-- The caller is waiting on Entry_Caller_Sleep, in Wait_For_Completion,
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-- or Wait_For_Completion_With_Timeout.
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--
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-- Conditional_Call:
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-- The caller might be in Wait_For_Completion,
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-- waiting for a rendezvous (possibly requeued without abort) to
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-- complete.
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--
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-- Asynchronous_Call:
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-- The caller may be executing in the abortable part an async. select,
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-- or on a time delay, if Entry_Call.State >= Was_Abortable.
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procedure Locked_Abort_To_Level
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(Self_ID : Task_Id;
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T : Task_Id;
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L : ATC_Level);
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pragma Inline (Locked_Abort_To_Level);
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-- Abort a task to a specified ATC level. Call this only with T locked
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end System.Tasking.Initialization;
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