6cbcc54138
* xeinfo.adb: Don't look for revision numbers. * xnmake.adb: Likewise. * xsinfo.adb: Likewise. * xsnames.adb: Likewise. * xtreeprs.adb: Likewise. From-SVN: r50768
263 lines
9.4 KiB
Ada
263 lines
9.4 KiB
Ada
------------------------------------------------------------------------------
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-- --
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-- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
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-- --
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-- S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S . --
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-- S P E C I F I C --
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-- --
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-- B o d y --
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-- --
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-- --
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-- Copyright (C) 1992-2001, 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 2, or (at your option) any later ver- --
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-- sion. GNARL 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. See the GNU General Public License --
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-- for more details. You should have received a copy of the GNU General --
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-- Public License distributed with GNARL; see file COPYING. If not, write --
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-- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
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-- MA 02111-1307, USA. --
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-- --
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-- As a special exception, if other files instantiate generics from this --
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-- unit, or you link this unit with other files to produce an executable, --
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-- this unit does not by itself cause the resulting executable to be --
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-- covered by the GNU General Public License. This exception does not --
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-- however invalidate any other reasons why the executable file might be --
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-- covered by the GNU Public License. --
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-- --
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-- GNARL was developed by the GNARL team at Florida State University. It is --
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-- now maintained by Ada Core Technologies, Inc. (http://www.gnat.com). --
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-- --
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------------------------------------------------------------------------------
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-- This is a POSIX version of this package where foreign threads are
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-- recognized.
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-- Currently, DEC Unix, SCO UnixWare, Solaris pthread, HPUX pthread,
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-- GNU/Linux threads and RTEMS use this version.
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with System.Task_Info;
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-- Use for Unspecified_Task_Info
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with System.Soft_Links;
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-- used to initialize TSD for a C thread, in function Self
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separate (System.Task_Primitives.Operations)
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package body Specific is
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------------------
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-- Local Data --
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------------------
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-- The followings are logically constants, but need to be initialized
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-- at run time.
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ATCB_Key : aliased pthread_key_t;
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-- Key used to find the Ada Task_ID associated with a thread
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-- The following are used to allow the Self function to
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-- automatically generate ATCB's for C threads that happen to call
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-- Ada procedure, which in turn happen to call the Ada runtime system.
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type Fake_ATCB;
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type Fake_ATCB_Ptr is access Fake_ATCB;
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type Fake_ATCB is record
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Stack_Base : Interfaces.C.unsigned := 0;
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-- A value of zero indicates the node is not in use.
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Next : Fake_ATCB_Ptr;
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Real_ATCB : aliased Ada_Task_Control_Block (0);
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end record;
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Fake_ATCB_List : Fake_ATCB_Ptr;
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-- A linear linked list.
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-- The list is protected by Single_RTS_Lock;
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-- Nodes are added to this list from the front.
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-- Once a node is added to this list, it is never removed.
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Fake_Task_Elaborated : aliased Boolean := True;
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-- Used to identified fake tasks (i.e., non-Ada Threads).
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Next_Fake_ATCB : Fake_ATCB_Ptr;
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-- Used to allocate one Fake_ATCB in advance. See comment in New_Fake_ATCB
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-----------------------
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-- Local Subprograms --
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-----------------------
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---------------------------------
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-- Support for New_Fake_ATCB --
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---------------------------------
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function New_Fake_ATCB return Task_ID;
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-- Allocate and Initialize a new ATCB. This code can safely be called from
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-- a foreign thread, as it doesn't access implicitly or explicitly
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-- "self" before having initialized the new ATCB.
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-------------------
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-- New_Fake_ATCB --
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-------------------
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function New_Fake_ATCB return Task_ID is
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Self_ID : Task_ID;
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P, Q : Fake_ATCB_Ptr;
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Succeeded : Boolean;
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Result : Interfaces.C.int;
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begin
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-- This section is ticklish.
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-- We dare not call anything that might require an ATCB, until
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-- we have the new ATCB in place.
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Lock_RTS;
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Q := null;
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P := Fake_ATCB_List;
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while P /= null loop
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if P.Stack_Base = 0 then
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Q := P;
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end if;
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P := P.Next;
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end loop;
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if Q = null then
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-- Create a new ATCB with zero entries.
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Self_ID := Next_Fake_ATCB.Real_ATCB'Access;
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Next_Fake_ATCB.Stack_Base := 1;
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Next_Fake_ATCB.Next := Fake_ATCB_List;
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Fake_ATCB_List := Next_Fake_ATCB;
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Next_Fake_ATCB := null;
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else
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-- Reuse an existing fake ATCB.
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Self_ID := Q.Real_ATCB'Access;
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Q.Stack_Base := 1;
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end if;
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-- Record this as the Task_ID for the current thread.
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Self_ID.Common.LL.Thread := pthread_self;
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Result := pthread_setspecific (ATCB_Key, To_Address (Self_ID));
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pragma Assert (Result = 0);
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-- Do the standard initializations
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System.Tasking.Initialize_ATCB
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(Self_ID, null, Null_Address, Null_Task, Fake_Task_Elaborated'Access,
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System.Priority'First, Task_Info.Unspecified_Task_Info, 0, Self_ID,
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Succeeded);
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pragma Assert (Succeeded);
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-- Finally, it is safe to use an allocator in this thread.
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if Next_Fake_ATCB = null then
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Next_Fake_ATCB := new Fake_ATCB;
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end if;
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Self_ID.Master_of_Task := 0;
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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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Self_ID.Common.State := Runnable;
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Self_ID.Awake_Count := 1;
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-- Since this is not an ordinary Ada task, we will start out undeferred
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Self_ID.Deferral_Level := 0;
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System.Soft_Links.Create_TSD (Self_ID.Common.Compiler_Data);
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-- ????
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-- The following call is commented out to avoid dependence on
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-- the System.Tasking.Initialization package.
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-- It seems that if we want Ada.Task_Attributes to work correctly
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-- for C threads we will need to raise the visibility of this soft
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-- link to System.Soft_Links.
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-- We are putting that off until this new functionality is otherwise
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-- stable.
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-- System.Tasking.Initialization.Initialize_Attributes_Link.all (T);
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for J in Known_Tasks'Range loop
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if Known_Tasks (J) = null then
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Known_Tasks (J) := Self_ID;
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Self_ID.Known_Tasks_Index := J;
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exit;
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end if;
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end loop;
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-- Must not unlock until Next_ATCB is again allocated.
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Unlock_RTS;
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return Self_ID;
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end New_Fake_ATCB;
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----------------
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-- Initialize --
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----------------
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procedure Initialize (Environment_Task : Task_ID) is
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Result : Interfaces.C.int;
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begin
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Result := pthread_key_create (ATCB_Key'Access, null);
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pragma Assert (Result = 0);
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Result := pthread_setspecific (ATCB_Key, To_Address (Environment_Task));
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pragma Assert (Result = 0);
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-- Create a free ATCB for use on the Fake_ATCB_List.
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Next_Fake_ATCB := new Fake_ATCB;
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end Initialize;
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---------
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-- Set --
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---------
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procedure Set (Self_Id : Task_ID) is
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Result : Interfaces.C.int;
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begin
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Result := pthread_setspecific (ATCB_Key, To_Address (Self_Id));
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pragma Assert (Result = 0);
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end Set;
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----------
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-- Self --
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----------
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-- To make Ada tasks and C threads interoperate better, we have added some
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-- functionality to Self. Suppose a C main program (with threads) calls an
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-- Ada procedure and the Ada procedure calls the tasking runtime system.
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-- Eventually, a call will be made to self. Since the call is not coming
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-- from an Ada task, there will be no corresponding ATCB.
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-- What we do in Self is to catch references that do not come from
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-- recognized Ada tasks, and create an ATCB for the calling thread.
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-- The new ATCB will be "detached" from the normal Ada task master
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-- hierarchy, much like the existing implicitly created signal-server
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-- tasks.
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function Self return Task_ID is
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Result : System.Address;
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begin
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Result := pthread_getspecific (ATCB_Key);
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-- If the key value is Null, then it is a non-Ada task.
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if Result = System.Null_Address then
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return New_Fake_ATCB;
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end if;
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return To_Task_ID (Result);
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end Self;
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end Specific;
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