| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS -- |
| -- -- |
| -- S Y S T E M . T A S K I N G . U T I L I T I E S -- |
| -- -- |
| -- S p e c -- |
| -- -- |
| -- Copyright (C) 1992-2023, 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 3, or (at your option) any later ver- -- |
| -- sion. GNAT 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. -- |
| -- -- |
| -- As a special exception under Section 7 of GPL version 3, you are granted -- |
| -- additional permissions described in the GCC Runtime Library Exception, -- |
| -- version 3.1, as published by the Free Software Foundation. -- |
| -- -- |
| -- You should have received a copy of the GNU General Public License and -- |
| -- a copy of the GCC Runtime Library Exception along with this program; -- |
| -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- |
| -- <http://www.gnu.org/licenses/>. -- |
| -- -- |
| -- GNARL was developed by the GNARL team at Florida State University. -- |
| -- Extensive contributions were provided by Ada Core Technologies, Inc. -- |
| -- -- |
| ------------------------------------------------------------------------------ |
| |
| -- This package provides RTS Internal Declarations. |
| -- These declarations are not part of the GNARLI |
| |
| with Ada.Unchecked_Conversion; |
| with System.Task_Primitives; |
| |
| package System.Tasking.Utilities is |
| |
| function ATCB_To_Address is new |
| Ada.Unchecked_Conversion (Task_Id, System.Task_Primitives.Task_Address); |
| |
| --------------------------------- |
| -- Task_Stage Related routines -- |
| --------------------------------- |
| |
| function Make_Independent return Boolean; |
| -- Move the current task to the outermost level (level 2) of the master |
| -- hierarchy of the environment task. That is one level further out |
| -- than normal tasks defined in library-level packages (level 3). The |
| -- environment task will wait for level 3 tasks to terminate normally, |
| -- then it will abort all the level 2 tasks. See Finalize_Global_Tasks |
| -- procedure for more information. |
| -- |
| -- This is a dangerous operation, and should never be used on nested tasks |
| -- or tasks that depend on any objects that might be finalized earlier than |
| -- the termination of the environment task. It is primarily for internal |
| -- use by the GNARL, to prevent such internal server tasks from preventing |
| -- a partition from terminating. |
| -- |
| -- Also note that the run time assumes that the parent of an independent |
| -- task is the environment task. If this is not the case, Make_Independent |
| -- will change the task's parent. This assumption is particularly |
| -- important for master level completion and for the computation of |
| -- Independent_Task_Count. |
| -- |
| -- NOTE WELL: Make_Independent should be called before the task reaches its |
| -- "begin", like this: |
| -- |
| -- task body Some_Independent_Task is |
| -- ... |
| -- Ignore : constant Boolean := Make_Independent; |
| -- ... |
| -- begin |
| -- |
| -- The return value is meaningless; the only reason this is a function is |
| -- to get around the Ada limitation that makes a procedure call |
| -- syntactically illegal before the "begin". |
| -- |
| -- Calling it before "begin" ensures that the call completes before the |
| -- activating task can proceed. This is important for preventing race |
| -- conditions. For example, if the environment task reaches |
| -- Finalize_Global_Tasks before some task has finished Make_Independent, |
| -- the program can hang. |
| -- |
| -- Note also that if a package declares independent tasks, it should not |
| -- initialize its package-body data after "begin" of the package, because |
| -- that's where the tasks are activated. Initializing such data before the |
| -- task activation helps prevent the tasks from accessing uninitialized |
| -- data. |
| |
| Independent_Task_Count : Natural := 0; |
| -- Number of independent tasks. This counter is incremented each time |
| -- Make_Independent is called. Note that if a server task terminates, |
| -- this counter will not be decremented. Since Make_Independent locks |
| -- the environment task (because every independent task depends on it), |
| -- this counter is protected by the environment task's lock. |
| |
| --------------------------------- |
| -- Task Abort Related Routines -- |
| --------------------------------- |
| |
| procedure Cancel_Queued_Entry_Calls (T : Task_Id); |
| -- Cancel any entry calls queued on target task. |
| -- Call this while holding T's lock. |
| |
| procedure Exit_One_ATC_Level (Self_ID : Task_Id); |
| pragma Inline (Exit_One_ATC_Level); |
| -- Call only with abort deferred and holding lock of Self_ID. |
| -- This is a bit of common code for all entry calls. |
| -- The effect is to exit one level of ATC nesting. |
| |
| procedure Abort_One_Task (Self_ID : Task_Id; T : Task_Id); |
| -- Similar to Locked_Abort_To_Level (Self_ID, T, Level_Completed_Task), |
| -- but: |
| -- (1) caller should be holding no locks |
| -- (2) may be called for tasks that have not yet been activated |
| -- (3) always aborts whole task |
| |
| procedure Abort_Tasks (Tasks : Task_List); |
| -- Abort_Tasks is called to initiate abort, however, the actual |
| -- aborting is done by aborted task by means of Abort_Handler |
| |
| procedure Make_Passive (Self_ID : Task_Id; Task_Completed : Boolean); |
| -- Update counts to indicate current task is either terminated or |
| -- accepting on a terminate alternative. Call holding no locks except |
| -- Global_Task_Lock when calling from Terminate_Task. |
| |
| end System.Tasking.Utilities; |
