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jeremybenn |
------------------------------------------------------------------------------
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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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-- B o d y --
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-- --
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-- Copyright (C) 1992-2009, 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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pragma Style_Checks (All_Checks);
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-- Turn off subprogram alpha ordering check, since we group soft link bodies
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-- and dummy soft link bodies together separately in this unit.
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pragma Polling (Off);
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-- Turn polling off for this package. We don't need polling during any of the
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-- routines in this package, and more to the point, if we try to poll it can
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-- cause infinite loops.
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with Ada.Exceptions;
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with System.Task_Primitives;
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with System.Task_Primitives.Operations;
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with System.Soft_Links;
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with System.Soft_Links.Tasking;
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with System.Tasking.Debug;
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with System.Parameters;
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package body System.Tasking.Initialization is
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package STPO renames System.Task_Primitives.Operations;
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package SSL renames System.Soft_Links;
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package AE renames Ada.Exceptions;
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use Parameters;
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use Task_Primitives.Operations;
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Global_Task_Lock : aliased System.Task_Primitives.RTS_Lock;
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-- This is a global lock; it is used to execute in mutual exclusion from
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-- all other tasks. It is only used by Task_Lock, Task_Unlock, and
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-- Final_Task_Unlock.
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----------------------------------------------------------------------
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-- Tasking versions of some services needed by non-tasking programs --
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----------------------------------------------------------------------
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procedure Abort_Defer;
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-- NON-INLINE versions without Self_ID for soft links
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procedure Abort_Undefer;
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-- NON-INLINE versions without Self_ID for soft links
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procedure Task_Lock;
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-- Locks out other tasks. Preceding a section of code by Task_Lock and
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-- following it by Task_Unlock creates a critical region. This is used
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-- for ensuring that a region of non-tasking code (such as code used to
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-- allocate memory) is tasking safe. Note that it is valid for calls to
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-- Task_Lock/Task_Unlock to be nested, and this must work properly, i.e.
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-- only the corresponding outer level Task_Unlock will actually unlock.
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procedure Task_Unlock;
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-- Releases lock previously set by call to Task_Lock. In the nested case,
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-- all nested locks must be released before other tasks competing for the
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-- tasking lock are released.
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function Get_Current_Excep return SSL.EOA;
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-- Task-safe version of SSL.Get_Current_Excep
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procedure Update_Exception
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(X : AE.Exception_Occurrence := SSL.Current_Target_Exception);
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-- Handle exception setting and check for pending actions
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function Task_Name return String;
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-- Returns current task's name
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------------------------
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-- Local Subprograms --
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------------------------
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----------------------------
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-- Tasking Initialization --
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----------------------------
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procedure Init_RTS;
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-- This procedure completes the initialization of the GNARL. The first part
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-- of the initialization is done in the body of System.Tasking. It consists
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-- of initializing global locks, and installing tasking versions of certain
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-- operations used by the compiler. Init_RTS is called during elaboration.
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--------------------------
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-- Change_Base_Priority --
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--------------------------
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-- Call only with abort deferred and holding Self_ID locked
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procedure Change_Base_Priority (T : Task_Id) is
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begin
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if T.Common.Base_Priority /= T.New_Base_Priority then
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T.Common.Base_Priority := T.New_Base_Priority;
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Set_Priority (T, T.Common.Base_Priority);
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end if;
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end Change_Base_Priority;
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------------------------
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-- Check_Abort_Status --
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------------------------
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function Check_Abort_Status return Integer is
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Self_ID : constant Task_Id := Self;
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begin
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if Self_ID /= null
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and then Self_ID.Deferral_Level = 0
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and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level
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then
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return 1;
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else
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return 0;
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end if;
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end Check_Abort_Status;
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-----------------
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-- Defer_Abort --
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-----------------
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procedure Defer_Abort (Self_ID : Task_Id) is
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begin
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if No_Abort then
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return;
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end if;
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pragma Assert (Self_ID.Deferral_Level = 0);
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-- pragma Assert
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-- (Self_ID.Pending_ATC_Level >= Self_ID.ATC_Nesting_Level);
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-- The above check has been useful in detecting mismatched defer/undefer
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-- pairs. You may uncomment it when testing on systems that support
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-- preemptive abort.
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-- If the OS supports preemptive abort (e.g. pthread_kill), it should
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-- have happened already. A problem is with systems that do not support
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-- preemptive abort, and so rely on polling. On such systems we may get
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-- false failures of the assertion, since polling for pending abort does
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-- no occur until the abort undefer operation.
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-- Even on systems that only poll for abort, the assertion may be useful
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-- for catching missed abort completion polling points. The operations
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-- that undefer abort poll for pending aborts. This covers most of the
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-- places where the core Ada semantics require abort to be caught,
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-- without any special attention. However, this generally happens on
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-- exit from runtime system call, which means a pending abort will not
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-- be noticed on the way into the runtime system. We considered adding a
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-- check for pending aborts at this point, but chose not to, because of
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-- the overhead. Instead, we searched for RTS calls where abort
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-- completion is required and a task could go farther than Ada allows
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-- before undeferring abort; we then modified the code to ensure the
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-- abort would be detected.
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Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1;
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end Defer_Abort;
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--------------------------
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-- Defer_Abort_Nestable --
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--------------------------
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procedure Defer_Abort_Nestable (Self_ID : Task_Id) is
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begin
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if No_Abort then
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return;
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end if;
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-- The following assertion is by default disabled. See the comment in
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-- Defer_Abort on the situations in which it may be useful to uncomment
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-- this assertion and enable the test.
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-- pragma Assert
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-- (Self_ID.Pending_ATC_Level >= Self_ID.ATC_Nesting_Level or else
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-- Self_ID.Deferral_Level > 0);
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Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1;
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end Defer_Abort_Nestable;
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-----------------
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-- Abort_Defer --
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-----------------
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procedure Abort_Defer is
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Self_ID : Task_Id;
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begin
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if No_Abort then
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return;
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end if;
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Self_ID := STPO.Self;
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Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1;
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end Abort_Defer;
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-----------------------
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-- Get_Current_Excep --
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-----------------------
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function Get_Current_Excep return SSL.EOA is
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begin
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return STPO.Self.Common.Compiler_Data.Current_Excep'Access;
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end Get_Current_Excep;
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-----------------------
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-- Do_Pending_Action --
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-----------------------
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-- Call only when holding no locks
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procedure Do_Pending_Action (Self_ID : Task_Id) is
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use type Ada.Exceptions.Exception_Id;
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begin
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pragma Assert (Self_ID = Self and then Self_ID.Deferral_Level = 0);
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-- Needs loop to recheck for pending action in case a new one occurred
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-- while we had abort deferred below.
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loop
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-- Temporarily defer abort so that we can lock Self_ID
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Self_ID.Deferral_Level := Self_ID.Deferral_Level + 1;
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if Single_Lock then
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Lock_RTS;
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end if;
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Write_Lock (Self_ID);
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Self_ID.Pending_Action := False;
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Unlock (Self_ID);
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if Single_Lock then
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Unlock_RTS;
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end if;
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-- Restore the original Deferral value
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Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1;
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if not Self_ID.Pending_Action then
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if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level then
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if not Self_ID.Aborting then
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Self_ID.Aborting := True;
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pragma Debug
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(Debug.Trace (Self_ID, "raise Abort_Signal", 'B'));
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raise Standard'Abort_Signal;
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pragma Assert (not Self_ID.ATC_Hack);
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elsif Self_ID.ATC_Hack then
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-- The solution really belongs in the Abort_Signal handler
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-- for async. entry calls. The present hack is very
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-- fragile. It relies that the very next point after
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-- Exit_One_ATC_Level at which the task becomes abortable
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-- will be the call to Undefer_Abort in the
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-- Abort_Signal handler.
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Self_ID.ATC_Hack := False;
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pragma Debug
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(Debug.Trace
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(Self_ID, "raise Abort_Signal (ATC hack)", 'B'));
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raise Standard'Abort_Signal;
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end if;
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end if;
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return;
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end if;
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end loop;
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end Do_Pending_Action;
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-----------------------
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-- Final_Task_Unlock --
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-----------------------
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300 |
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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.
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-- There is a very interesting potential race condition there, where the
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-- old task may run concurrently with a new task that is allocated the old
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-- tasks (now reused) ATCB. The critical thing here is to not make any
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-- reference to the ATCB after the lock is released. See also comments on
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-- Terminate_Task and Unlock.
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309 |
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procedure Final_Task_Unlock (Self_ID : Task_Id) is
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begin
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pragma Assert (Self_ID.Common.Global_Task_Lock_Nesting = 1);
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Unlock (Global_Task_Lock'Access, Global_Lock => True);
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end Final_Task_Unlock;
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316 |
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--------------
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317 |
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-- Init_RTS --
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318 |
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--------------
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319 |
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procedure Init_RTS is
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Self_Id : Task_Id;
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begin
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323 |
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Tasking.Initialize;
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324 |
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325 |
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-- Terminate run time (regular vs restricted) specific initialization
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-- of the environment task.
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327 |
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Self_Id := Environment_Task;
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Self_Id.Master_of_Task := Environment_Task_Level;
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330 |
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Self_Id.Master_Within := Self_Id.Master_of_Task + 1;
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for L in Self_Id.Entry_Calls'Range loop
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Self_Id.Entry_Calls (L).Self := Self_Id;
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Self_Id.Entry_Calls (L).Level := L;
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end loop;
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336 |
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337 |
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Self_Id.Awake_Count := 1;
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338 |
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Self_Id.Alive_Count := 1;
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339 |
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340 |
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-- Normally, a task starts out with internal master nesting level one
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341 |
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-- larger than external master nesting level. It is incremented to one
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342 |
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-- by Enter_Master, which is called in the task body only if the
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343 |
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-- compiler thinks the task may have dependent tasks. There is no
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344 |
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-- corresponding call to Enter_Master for the environment task, so we
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-- would need to increment it to 2 here. Instead, we set it to 3. By
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346 |
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-- doing this we reserve the level 2 for server tasks of the runtime
|
347 |
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-- system. The environment task does not need to wait for these server
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348 |
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349 |
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Self_Id.Master_Within := Library_Task_Level;
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350 |
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351 |
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-- Initialize lock used to implement mutual exclusion between all tasks
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352 |
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353 |
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Initialize_Lock (Global_Task_Lock'Access, STPO.Global_Task_Level);
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354 |
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355 |
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-- Notify that the tasking run time has been elaborated so that
|
356 |
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-- the tasking version of the soft links can be used.
|
357 |
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|
358 |
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if not No_Abort then
|
359 |
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SSL.Abort_Defer := Abort_Defer'Access;
|
360 |
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SSL.Abort_Undefer := Abort_Undefer'Access;
|
361 |
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end if;
|
362 |
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|
363 |
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SSL.Lock_Task := Task_Lock'Access;
|
364 |
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SSL.Unlock_Task := Task_Unlock'Access;
|
365 |
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SSL.Check_Abort_Status := Check_Abort_Status'Access;
|
366 |
|
|
SSL.Task_Name := Task_Name'Access;
|
367 |
|
|
SSL.Update_Exception := Update_Exception'Access;
|
368 |
|
|
SSL.Get_Current_Excep := Get_Current_Excep'Access;
|
369 |
|
|
|
370 |
|
|
-- Initialize the tasking soft links (if not done yet) that are common
|
371 |
|
|
-- to the full and the restricted run times.
|
372 |
|
|
|
373 |
|
|
SSL.Tasking.Init_Tasking_Soft_Links;
|
374 |
|
|
|
375 |
|
|
-- Abort is deferred in a new ATCB, so we need to undefer abort at this
|
376 |
|
|
-- stage to make the environment task abortable.
|
377 |
|
|
|
378 |
|
|
Undefer_Abort (Environment_Task);
|
379 |
|
|
end Init_RTS;
|
380 |
|
|
|
381 |
|
|
---------------------------
|
382 |
|
|
-- Locked_Abort_To_Level--
|
383 |
|
|
---------------------------
|
384 |
|
|
|
385 |
|
|
-- Abort a task to the specified ATC nesting level.
|
386 |
|
|
-- Call this only with T locked.
|
387 |
|
|
|
388 |
|
|
-- An earlier version of this code contained a call to Wakeup. That should
|
389 |
|
|
-- not be necessary here, if Abort_Task is implemented correctly, since
|
390 |
|
|
-- Abort_Task should include the effect of Wakeup. However, the above call
|
391 |
|
|
-- was in earlier versions of this file, and at least for some targets
|
392 |
|
|
-- Abort_Task has not been doing Wakeup. It should not hurt to uncomment
|
393 |
|
|
-- the above call, until the error is corrected for all targets.
|
394 |
|
|
|
395 |
|
|
-- See extended comments in package body System.Tasking.Abort for the
|
396 |
|
|
-- overall design of the implementation of task abort.
|
397 |
|
|
-- ??? there is no such package ???
|
398 |
|
|
|
399 |
|
|
-- If the task is sleeping it will be in an abort-deferred region, and will
|
400 |
|
|
-- not have Abort_Signal raised by Abort_Task. Such an "abort deferral" is
|
401 |
|
|
-- just to protect the RTS internals, and not necessarily required to
|
402 |
|
|
-- enforce Ada semantics. Abort_Task should wake the task up and let it
|
403 |
|
|
-- decide if it wants to complete the aborted construct immediately.
|
404 |
|
|
|
405 |
|
|
-- Note that the effect of the low-level Abort_Task is not persistent.
|
406 |
|
|
-- If the target task is not blocked, this wakeup will be missed.
|
407 |
|
|
|
408 |
|
|
-- We don't bother calling Abort_Task if this task is aborting itself,
|
409 |
|
|
-- since we are inside the RTS and have abort deferred. Similarly, We don't
|
410 |
|
|
-- bother to call Abort_Task if T is terminated, since there is no need to
|
411 |
|
|
-- abort a terminated task, and it could be dangerous to try if the task
|
412 |
|
|
-- has stopped executing.
|
413 |
|
|
|
414 |
|
|
-- Note that an earlier version of this code had some false reasoning about
|
415 |
|
|
-- being able to reliably wake up a task that had suspended on a blocking
|
416 |
|
|
-- system call that does not atomically release the task's lock (e.g., UNIX
|
417 |
|
|
-- nanosleep, which we once thought could be used to implement delays).
|
418 |
|
|
-- That still left the possibility of missed wakeups.
|
419 |
|
|
|
420 |
|
|
-- We cannot safely call Vulnerable_Complete_Activation here, since that
|
421 |
|
|
-- requires locking Self_ID.Parent. The anti-deadlock lock ordering rules
|
422 |
|
|
-- would then require us to release the lock on Self_ID first, which would
|
423 |
|
|
-- create a timing window for other tasks to lock Self_ID. This is
|
424 |
|
|
-- significant for tasks that may be aborted before their execution can
|
425 |
|
|
-- enter the task body, and so they do not get a chance to call
|
426 |
|
|
-- Complete_Task. The actual work for this case is done in Terminate_Task.
|
427 |
|
|
|
428 |
|
|
procedure Locked_Abort_To_Level
|
429 |
|
|
(Self_ID : Task_Id;
|
430 |
|
|
T : Task_Id;
|
431 |
|
|
L : ATC_Level)
|
432 |
|
|
is
|
433 |
|
|
begin
|
434 |
|
|
if not T.Aborting and then T /= Self_ID then
|
435 |
|
|
case T.Common.State is
|
436 |
|
|
when Unactivated | Terminated =>
|
437 |
|
|
pragma Assert (False);
|
438 |
|
|
null;
|
439 |
|
|
|
440 |
|
|
when Activating | Runnable =>
|
441 |
|
|
|
442 |
|
|
-- This is needed to cancel an asynchronous protected entry
|
443 |
|
|
-- call during a requeue with abort.
|
444 |
|
|
|
445 |
|
|
T.Entry_Calls
|
446 |
|
|
(T.ATC_Nesting_Level).Cancellation_Attempted := True;
|
447 |
|
|
|
448 |
|
|
when Interrupt_Server_Blocked_On_Event_Flag =>
|
449 |
|
|
null;
|
450 |
|
|
|
451 |
|
|
when Delay_Sleep |
|
452 |
|
|
Async_Select_Sleep |
|
453 |
|
|
Interrupt_Server_Idle_Sleep |
|
454 |
|
|
Interrupt_Server_Blocked_Interrupt_Sleep |
|
455 |
|
|
Timer_Server_Sleep |
|
456 |
|
|
AST_Server_Sleep =>
|
457 |
|
|
Wakeup (T, T.Common.State);
|
458 |
|
|
|
459 |
|
|
when Acceptor_Sleep | Acceptor_Delay_Sleep =>
|
460 |
|
|
T.Open_Accepts := null;
|
461 |
|
|
Wakeup (T, T.Common.State);
|
462 |
|
|
|
463 |
|
|
when Entry_Caller_Sleep =>
|
464 |
|
|
T.Entry_Calls
|
465 |
|
|
(T.ATC_Nesting_Level).Cancellation_Attempted := True;
|
466 |
|
|
Wakeup (T, T.Common.State);
|
467 |
|
|
|
468 |
|
|
when Activator_Sleep |
|
469 |
|
|
Master_Completion_Sleep |
|
470 |
|
|
Master_Phase_2_Sleep |
|
471 |
|
|
Asynchronous_Hold =>
|
472 |
|
|
null;
|
473 |
|
|
end case;
|
474 |
|
|
end if;
|
475 |
|
|
|
476 |
|
|
if T.Pending_ATC_Level > L then
|
477 |
|
|
T.Pending_ATC_Level := L;
|
478 |
|
|
T.Pending_Action := True;
|
479 |
|
|
|
480 |
|
|
if L = 0 then
|
481 |
|
|
T.Callable := False;
|
482 |
|
|
end if;
|
483 |
|
|
|
484 |
|
|
-- This prevents aborted task from accepting calls
|
485 |
|
|
|
486 |
|
|
if T.Aborting then
|
487 |
|
|
|
488 |
|
|
-- The test above is just a heuristic, to reduce wasteful
|
489 |
|
|
-- calls to Abort_Task. We are holding T locked, and this
|
490 |
|
|
-- value will not be set to False except with T also locked,
|
491 |
|
|
-- inside Exit_One_ATC_Level, so we should not miss wakeups.
|
492 |
|
|
|
493 |
|
|
if T.Common.State = Acceptor_Sleep
|
494 |
|
|
or else
|
495 |
|
|
T.Common.State = Acceptor_Delay_Sleep
|
496 |
|
|
then
|
497 |
|
|
T.Open_Accepts := null;
|
498 |
|
|
end if;
|
499 |
|
|
|
500 |
|
|
elsif T /= Self_ID and then
|
501 |
|
|
(T.Common.State = Runnable
|
502 |
|
|
or else T.Common.State = Interrupt_Server_Blocked_On_Event_Flag)
|
503 |
|
|
|
504 |
|
|
-- The task is blocked on a system call waiting for the
|
505 |
|
|
-- completion event. In this case Abort_Task may need to take
|
506 |
|
|
-- special action in order to succeed. Example system: VMS.
|
507 |
|
|
|
508 |
|
|
then
|
509 |
|
|
Abort_Task (T);
|
510 |
|
|
end if;
|
511 |
|
|
end if;
|
512 |
|
|
end Locked_Abort_To_Level;
|
513 |
|
|
|
514 |
|
|
--------------------------------
|
515 |
|
|
-- Remove_From_All_Tasks_List --
|
516 |
|
|
--------------------------------
|
517 |
|
|
|
518 |
|
|
procedure Remove_From_All_Tasks_List (T : Task_Id) is
|
519 |
|
|
C : Task_Id;
|
520 |
|
|
Previous : Task_Id;
|
521 |
|
|
|
522 |
|
|
begin
|
523 |
|
|
pragma Debug
|
524 |
|
|
(Debug.Trace (Self, "Remove_From_All_Tasks_List", 'C'));
|
525 |
|
|
|
526 |
|
|
Previous := Null_Task;
|
527 |
|
|
C := All_Tasks_List;
|
528 |
|
|
while C /= Null_Task loop
|
529 |
|
|
if C = T then
|
530 |
|
|
if Previous = Null_Task then
|
531 |
|
|
All_Tasks_List := All_Tasks_List.Common.All_Tasks_Link;
|
532 |
|
|
else
|
533 |
|
|
Previous.Common.All_Tasks_Link := C.Common.All_Tasks_Link;
|
534 |
|
|
end if;
|
535 |
|
|
|
536 |
|
|
return;
|
537 |
|
|
end if;
|
538 |
|
|
|
539 |
|
|
Previous := C;
|
540 |
|
|
C := C.Common.All_Tasks_Link;
|
541 |
|
|
end loop;
|
542 |
|
|
|
543 |
|
|
pragma Assert (False);
|
544 |
|
|
end Remove_From_All_Tasks_List;
|
545 |
|
|
|
546 |
|
|
---------------
|
547 |
|
|
-- Task_Lock --
|
548 |
|
|
---------------
|
549 |
|
|
|
550 |
|
|
procedure Task_Lock (Self_ID : Task_Id) is
|
551 |
|
|
begin
|
552 |
|
|
Self_ID.Common.Global_Task_Lock_Nesting :=
|
553 |
|
|
Self_ID.Common.Global_Task_Lock_Nesting + 1;
|
554 |
|
|
|
555 |
|
|
if Self_ID.Common.Global_Task_Lock_Nesting = 1 then
|
556 |
|
|
Defer_Abort_Nestable (Self_ID);
|
557 |
|
|
Write_Lock (Global_Task_Lock'Access, Global_Lock => True);
|
558 |
|
|
end if;
|
559 |
|
|
end Task_Lock;
|
560 |
|
|
|
561 |
|
|
procedure Task_Lock is
|
562 |
|
|
begin
|
563 |
|
|
Task_Lock (STPO.Self);
|
564 |
|
|
end Task_Lock;
|
565 |
|
|
|
566 |
|
|
---------------
|
567 |
|
|
-- Task_Name --
|
568 |
|
|
---------------
|
569 |
|
|
|
570 |
|
|
function Task_Name return String is
|
571 |
|
|
Self_Id : constant Task_Id := STPO.Self;
|
572 |
|
|
begin
|
573 |
|
|
return Self_Id.Common.Task_Image (1 .. Self_Id.Common.Task_Image_Len);
|
574 |
|
|
end Task_Name;
|
575 |
|
|
|
576 |
|
|
-----------------
|
577 |
|
|
-- Task_Unlock --
|
578 |
|
|
-----------------
|
579 |
|
|
|
580 |
|
|
procedure Task_Unlock (Self_ID : Task_Id) is
|
581 |
|
|
begin
|
582 |
|
|
pragma Assert (Self_ID.Common.Global_Task_Lock_Nesting > 0);
|
583 |
|
|
Self_ID.Common.Global_Task_Lock_Nesting :=
|
584 |
|
|
Self_ID.Common.Global_Task_Lock_Nesting - 1;
|
585 |
|
|
|
586 |
|
|
if Self_ID.Common.Global_Task_Lock_Nesting = 0 then
|
587 |
|
|
Unlock (Global_Task_Lock'Access, Global_Lock => True);
|
588 |
|
|
Undefer_Abort_Nestable (Self_ID);
|
589 |
|
|
end if;
|
590 |
|
|
end Task_Unlock;
|
591 |
|
|
|
592 |
|
|
procedure Task_Unlock is
|
593 |
|
|
begin
|
594 |
|
|
Task_Unlock (STPO.Self);
|
595 |
|
|
end Task_Unlock;
|
596 |
|
|
|
597 |
|
|
-------------------
|
598 |
|
|
-- Undefer_Abort --
|
599 |
|
|
-------------------
|
600 |
|
|
|
601 |
|
|
-- Precondition : Self does not hold any locks!
|
602 |
|
|
|
603 |
|
|
-- Undefer_Abort is called on any abort completion point (aka.
|
604 |
|
|
-- synchronization point). It performs the following actions if they
|
605 |
|
|
-- are pending: (1) change the base priority, (2) abort the task.
|
606 |
|
|
|
607 |
|
|
-- The priority change has to occur before abort. Otherwise, it would
|
608 |
|
|
-- take effect no earlier than the next abort completion point.
|
609 |
|
|
|
610 |
|
|
procedure Undefer_Abort (Self_ID : Task_Id) is
|
611 |
|
|
begin
|
612 |
|
|
if No_Abort then
|
613 |
|
|
return;
|
614 |
|
|
end if;
|
615 |
|
|
|
616 |
|
|
pragma Assert (Self_ID.Deferral_Level = 1);
|
617 |
|
|
|
618 |
|
|
Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1;
|
619 |
|
|
|
620 |
|
|
if Self_ID.Deferral_Level = 0 then
|
621 |
|
|
pragma Assert (Check_No_Locks (Self_ID));
|
622 |
|
|
|
623 |
|
|
if Self_ID.Pending_Action then
|
624 |
|
|
Do_Pending_Action (Self_ID);
|
625 |
|
|
end if;
|
626 |
|
|
end if;
|
627 |
|
|
end Undefer_Abort;
|
628 |
|
|
|
629 |
|
|
----------------------------
|
630 |
|
|
-- Undefer_Abort_Nestable --
|
631 |
|
|
----------------------------
|
632 |
|
|
|
633 |
|
|
-- An earlier version would re-defer abort if an abort is in progress.
|
634 |
|
|
-- Then, we modified the effect of the raise statement so that it defers
|
635 |
|
|
-- abort until control reaches a handler. That was done to prevent
|
636 |
|
|
-- "skipping over" a handler if another asynchronous abort occurs during
|
637 |
|
|
-- the propagation of the abort to the handler.
|
638 |
|
|
|
639 |
|
|
-- There has been talk of reversing that decision, based on a newer
|
640 |
|
|
-- implementation of exception propagation. Care must be taken to evaluate
|
641 |
|
|
-- how such a change would interact with the above code and all the places
|
642 |
|
|
-- where abort-deferral is used to bridge over critical transitions, such
|
643 |
|
|
-- as entry to the scope of a region with a finalizer and entry into the
|
644 |
|
|
-- body of an accept-procedure.
|
645 |
|
|
|
646 |
|
|
procedure Undefer_Abort_Nestable (Self_ID : Task_Id) is
|
647 |
|
|
begin
|
648 |
|
|
if No_Abort then
|
649 |
|
|
return;
|
650 |
|
|
end if;
|
651 |
|
|
|
652 |
|
|
pragma Assert (Self_ID.Deferral_Level > 0);
|
653 |
|
|
|
654 |
|
|
Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1;
|
655 |
|
|
|
656 |
|
|
if Self_ID.Deferral_Level = 0 then
|
657 |
|
|
|
658 |
|
|
pragma Assert (Check_No_Locks (Self_ID));
|
659 |
|
|
|
660 |
|
|
if Self_ID.Pending_Action then
|
661 |
|
|
Do_Pending_Action (Self_ID);
|
662 |
|
|
end if;
|
663 |
|
|
end if;
|
664 |
|
|
end Undefer_Abort_Nestable;
|
665 |
|
|
|
666 |
|
|
-------------------
|
667 |
|
|
-- Abort_Undefer --
|
668 |
|
|
-------------------
|
669 |
|
|
|
670 |
|
|
procedure Abort_Undefer is
|
671 |
|
|
Self_ID : Task_Id;
|
672 |
|
|
begin
|
673 |
|
|
if No_Abort then
|
674 |
|
|
return;
|
675 |
|
|
end if;
|
676 |
|
|
|
677 |
|
|
Self_ID := STPO.Self;
|
678 |
|
|
|
679 |
|
|
if Self_ID.Deferral_Level = 0 then
|
680 |
|
|
|
681 |
|
|
-- In case there are different views on whether Abort is supported
|
682 |
|
|
-- between the expander and the run time, we may end up with
|
683 |
|
|
-- Self_ID.Deferral_Level being equal to zero, when called from
|
684 |
|
|
-- the procedure created by the expander that corresponds to a
|
685 |
|
|
-- task body.
|
686 |
|
|
|
687 |
|
|
-- In this case, there's nothing to be done
|
688 |
|
|
|
689 |
|
|
-- See related code in System.Tasking.Stages.Create_Task resetting
|
690 |
|
|
-- Deferral_Level when System.Restrictions.Abort_Allowed is False.
|
691 |
|
|
|
692 |
|
|
return;
|
693 |
|
|
end if;
|
694 |
|
|
|
695 |
|
|
pragma Assert (Self_ID.Deferral_Level > 0);
|
696 |
|
|
Self_ID.Deferral_Level := Self_ID.Deferral_Level - 1;
|
697 |
|
|
|
698 |
|
|
if Self_ID.Deferral_Level = 0 then
|
699 |
|
|
pragma Assert (Check_No_Locks (Self_ID));
|
700 |
|
|
|
701 |
|
|
if Self_ID.Pending_Action then
|
702 |
|
|
Do_Pending_Action (Self_ID);
|
703 |
|
|
end if;
|
704 |
|
|
end if;
|
705 |
|
|
end Abort_Undefer;
|
706 |
|
|
|
707 |
|
|
----------------------
|
708 |
|
|
-- Update_Exception --
|
709 |
|
|
----------------------
|
710 |
|
|
|
711 |
|
|
-- Call only when holding no locks
|
712 |
|
|
|
713 |
|
|
procedure Update_Exception
|
714 |
|
|
(X : AE.Exception_Occurrence := SSL.Current_Target_Exception)
|
715 |
|
|
is
|
716 |
|
|
Self_Id : constant Task_Id := Self;
|
717 |
|
|
use Ada.Exceptions;
|
718 |
|
|
|
719 |
|
|
begin
|
720 |
|
|
Save_Occurrence (Self_Id.Common.Compiler_Data.Current_Excep, X);
|
721 |
|
|
|
722 |
|
|
if Self_Id.Deferral_Level = 0 then
|
723 |
|
|
if Self_Id.Pending_Action then
|
724 |
|
|
Self_Id.Pending_Action := False;
|
725 |
|
|
Self_Id.Deferral_Level := Self_Id.Deferral_Level + 1;
|
726 |
|
|
|
727 |
|
|
if Single_Lock then
|
728 |
|
|
Lock_RTS;
|
729 |
|
|
end if;
|
730 |
|
|
|
731 |
|
|
Write_Lock (Self_Id);
|
732 |
|
|
Self_Id.Pending_Action := False;
|
733 |
|
|
Unlock (Self_Id);
|
734 |
|
|
|
735 |
|
|
if Single_Lock then
|
736 |
|
|
Unlock_RTS;
|
737 |
|
|
end if;
|
738 |
|
|
|
739 |
|
|
Self_Id.Deferral_Level := Self_Id.Deferral_Level - 1;
|
740 |
|
|
|
741 |
|
|
if Self_Id.Pending_ATC_Level < Self_Id.ATC_Nesting_Level then
|
742 |
|
|
if not Self_Id.Aborting then
|
743 |
|
|
Self_Id.Aborting := True;
|
744 |
|
|
raise Standard'Abort_Signal;
|
745 |
|
|
end if;
|
746 |
|
|
end if;
|
747 |
|
|
end if;
|
748 |
|
|
end if;
|
749 |
|
|
end Update_Exception;
|
750 |
|
|
|
751 |
|
|
--------------------------
|
752 |
|
|
-- Wakeup_Entry_Caller --
|
753 |
|
|
--------------------------
|
754 |
|
|
|
755 |
|
|
-- This is called at the end of service of an entry call, to abort the
|
756 |
|
|
-- caller if he is in an abortable part, and to wake up the caller if it
|
757 |
|
|
-- is on Entry_Caller_Sleep. It assumes that the call is already off-queue.
|
758 |
|
|
|
759 |
|
|
-- (This enforces the rule that a task must be off-queue if its state is
|
760 |
|
|
-- Done or Cancelled.) Call it holding the lock of Entry_Call.Self.
|
761 |
|
|
|
762 |
|
|
-- Timed_Call or Simple_Call:
|
763 |
|
|
-- The caller is waiting on Entry_Caller_Sleep, in
|
764 |
|
|
-- Wait_For_Completion, or Wait_For_Completion_With_Timeout.
|
765 |
|
|
|
766 |
|
|
-- Conditional_Call:
|
767 |
|
|
-- The caller might be in Wait_For_Completion,
|
768 |
|
|
-- waiting for a rendezvous (possibly requeued without abort)
|
769 |
|
|
-- to complete.
|
770 |
|
|
|
771 |
|
|
-- Asynchronous_Call:
|
772 |
|
|
-- The caller may be executing in the abortable part o
|
773 |
|
|
-- an async. select, or on a time delay,
|
774 |
|
|
-- if Entry_Call.State >= Was_Abortable.
|
775 |
|
|
|
776 |
|
|
procedure Wakeup_Entry_Caller
|
777 |
|
|
(Self_ID : Task_Id;
|
778 |
|
|
Entry_Call : Entry_Call_Link;
|
779 |
|
|
New_State : Entry_Call_State)
|
780 |
|
|
is
|
781 |
|
|
Caller : constant Task_Id := Entry_Call.Self;
|
782 |
|
|
|
783 |
|
|
begin
|
784 |
|
|
pragma Debug (Debug.Trace
|
785 |
|
|
(Self_ID, "Wakeup_Entry_Caller", 'E', Caller));
|
786 |
|
|
pragma Assert (New_State = Done or else New_State = Cancelled);
|
787 |
|
|
|
788 |
|
|
pragma Assert (Caller.Common.State /= Unactivated);
|
789 |
|
|
|
790 |
|
|
Entry_Call.State := New_State;
|
791 |
|
|
|
792 |
|
|
if Entry_Call.Mode = Asynchronous_Call then
|
793 |
|
|
|
794 |
|
|
-- Abort the caller in his abortable part, but do so only if call has
|
795 |
|
|
-- been queued abortably.
|
796 |
|
|
|
797 |
|
|
if Entry_Call.State >= Was_Abortable or else New_State = Done then
|
798 |
|
|
Locked_Abort_To_Level (Self_ID, Caller, Entry_Call.Level - 1);
|
799 |
|
|
end if;
|
800 |
|
|
|
801 |
|
|
elsif Caller.Common.State = Entry_Caller_Sleep then
|
802 |
|
|
Wakeup (Caller, Entry_Caller_Sleep);
|
803 |
|
|
end if;
|
804 |
|
|
end Wakeup_Entry_Caller;
|
805 |
|
|
|
806 |
|
|
-----------------------
|
807 |
|
|
-- Soft-Link Dummies --
|
808 |
|
|
-----------------------
|
809 |
|
|
|
810 |
|
|
-- These are dummies for subprograms that are only needed by certain
|
811 |
|
|
-- optional run-time system packages. If they are needed, the soft links
|
812 |
|
|
-- will be redirected to the real subprogram by elaboration of the
|
813 |
|
|
-- subprogram body where the real subprogram is declared.
|
814 |
|
|
|
815 |
|
|
procedure Finalize_Attributes (T : Task_Id) is
|
816 |
|
|
pragma Unreferenced (T);
|
817 |
|
|
begin
|
818 |
|
|
null;
|
819 |
|
|
end Finalize_Attributes;
|
820 |
|
|
|
821 |
|
|
procedure Initialize_Attributes (T : Task_Id) is
|
822 |
|
|
pragma Unreferenced (T);
|
823 |
|
|
begin
|
824 |
|
|
null;
|
825 |
|
|
end Initialize_Attributes;
|
826 |
|
|
|
827 |
|
|
begin
|
828 |
|
|
Init_RTS;
|
829 |
|
|
end System.Tasking.Initialization;
|