------------------------------------------------------------------------------ -- -- -- 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) 1992-2018, 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 -- -- . -- -- -- -- 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 (or RTS_Lock in Single_Lock mode). 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, 0), 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, and RTS_Lock when -- Single_Lock is True. end System.Tasking.Utilities;