------------------------------------------------------------------------------
-- --
--- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
+-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
-- S Y S T E M . T A S K I N G . S T A G E S --
-- --
-- B o d y --
-- --
--- Copyright (C) 1992-2004, Free Software Foundation, Inc. --
+-- Copyright (C) 1992-2009, 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 2, or (at your option) any later ver- --
--- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
+-- 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. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNARL; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
--- As a special exception, if other files instantiate generics from this --
--- unit, or you link this unit with other files to produce an executable, --
--- this unit does not by itself cause the resulting executable to be --
--- covered by the GNU General Public License. This exception does not --
--- however invalidate any other reasons why the executable file might be --
--- covered by the GNU Public License. --
+-- 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. --
------------------------------------------------------------------------------
pragma Polling (Off);
--- Turn off polling, we do not want ATC polling to take place during
--- tasking operations. It causes infinite loops and other problems.
+-- Turn off polling, we do not want ATC polling to take place during tasking
+-- operations. It causes infinite loops and other problems.
with Ada.Exceptions;
--- used for Raise_Exception
+with Ada.Unchecked_Deallocation;
with System.Tasking.Debug;
--- used for enabling tasking facilities with gdb
-
with System.Address_Image;
--- used for the function itself.
-
-with System.Parameters;
--- used for Size_Type
--- Single_Lock
--- Runtime_Traces
-
-with System.Task_Info;
--- used for Task_Info_Type
-
+with System.Task_Primitives;
with System.Task_Primitives.Operations;
--- used for Finalize_Lock
--- Enter_Task
--- Write_Lock
--- Unlock
--- Sleep
--- Wakeup
--- Get_Priority
--- Lock/Unlock_RTS
--- New_ATCB
-
-with System.Soft_Links;
--- These are procedure pointers to non-tasking routines that use
--- task specific data. In the absence of tasking, these routines
--- refer to global data. In the presense of tasking, they must be
--- replaced with pointers to task-specific versions.
--- Also used for Create_TSD, Destroy_TSD, Get_Current_Excep
-
-with System.Tasking.Initialization;
--- Used for Remove_From_All_Tasks_List
--- Defer_Abort
--- Undefer_Abort
--- Initialization.Poll_Base_Priority_Change
--- Finalize_Attributes_Link
--- Initialize_Attributes_Link
-
-pragma Elaborate_All (System.Tasking.Initialization);
--- This insures that tasking is initialized if any tasks are created.
-
with System.Tasking.Utilities;
--- Used for Make_Passive
--- Abort_One_Task
-
with System.Tasking.Queuing;
--- Used for Dequeue_Head
-
with System.Tasking.Rendezvous;
--- Used for Call_Simple
-
with System.OS_Primitives;
--- Used for Delay_Modes
-
-with System.Finalization_Implementation;
--- Used for System.Finalization_Implementation.Finalize_Global_List
-
with System.Secondary_Stack;
--- used for SS_Init
-
with System.Storage_Elements;
--- used for Storage_Array
-
+with System.Restrictions;
with System.Standard_Library;
--- used for Exception_Trace
-
with System.Traces.Tasking;
--- used for Send_Trace_Info
+with System.Stack_Usage;
+
+with System.Soft_Links;
+-- These are procedure pointers to non-tasking routines that use task
+-- specific data. In the absence of tasking, these routines refer to global
+-- data. In the presence of tasking, they must be replaced with pointers to
+-- task-specific versions. Also used for Create_TSD, Destroy_TSD,
+-- Get_Current_Excep, Finalize_Global_List, Task_Termination, Handler.
-with Unchecked_Deallocation;
--- To recover from failure of ATCB initialization.
+with System.Tasking.Initialization;
+pragma Elaborate_All (System.Tasking.Initialization);
+-- This insures that tasking is initialized if any tasks are created
package body System.Tasking.Stages is
-----------------------
procedure Free is new
- Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
+ Ada.Unchecked_Deallocation (Ada_Task_Control_Block, Task_Id);
+
+ procedure Free_Entry_Names (T : Task_Id);
+ -- Deallocate all string names associated with task entries
procedure Trace_Unhandled_Exception_In_Task (Self_Id : Task_Id);
-- This procedure outputs the task specific message for exception
-- tracing purposes.
procedure Task_Wrapper (Self_ID : Task_Id);
- -- This is the procedure that is called by the GNULL from the
- -- new context when a task is created. It waits for activation
- -- and then calls the task body procedure. When the task body
- -- procedure completes, it terminates the task.
+ pragma Convention (C, Task_Wrapper);
+ -- This is the procedure that is called by the GNULL from the new context
+ -- when a task is created. It waits for activation and then calls the task
+ -- body procedure. When the task body procedure completes, it terminates
+ -- the task.
+ --
+ -- The Task_Wrapper's address will be provided to the underlying threads
+ -- library as the task entry point. Convention C is what makes most sense
+ -- for that purpose (Export C would make the function globally visible,
+ -- and affect the link name on which GDB depends). This will in addition
+ -- trigger an automatic stack alignment suitable for GCC's assumptions if
+ -- need be.
+
+ -- "Vulnerable_..." in the procedure names below means they must be called
+ -- with abort deferred.
procedure Vulnerable_Complete_Task (Self_ID : Task_Id);
- -- Complete the calling task.
- -- This procedure must be called with abort deferred.
- -- It should only be called by Complete_Task and
- -- Finalizate_Global_Tasks (for the environment task).
+ -- Complete the calling task. This procedure must be called with
+ -- abort deferred. It should only be called by Complete_Task and
+ -- Finalize_Global_Tasks (for the environment task).
procedure Vulnerable_Complete_Master (Self_ID : Task_Id);
- -- Complete the current master of the calling task.
- -- This procedure must be called with abort deferred.
- -- It should only be called by Vulnerable_Complete_Task and
- -- Complete_Master.
+ -- Complete the current master of the calling task. This procedure
+ -- must be called with abort deferred. It should only be called by
+ -- Vulnerable_Complete_Task and Complete_Master.
procedure Vulnerable_Complete_Activation (Self_ID : Task_Id);
- -- Signal to Self_ID's activator that Self_ID has
- -- completed activation.
- --
- -- Call this procedure with abort deferred.
+ -- Signal to Self_ID's activator that Self_ID has completed activation.
+ -- This procedure must be called with abort deferred.
procedure Abort_Dependents (Self_ID : Task_Id);
- -- Abort all the direct dependents of Self at its current master
- -- nesting level, plus all of their dependents, transitively.
- -- RTS_Lock should be locked by the caller.
+ -- Abort all the direct dependents of Self at its current master nesting
+ -- level, plus all of their dependents, transitively. RTS_Lock should be
+ -- locked by the caller.
procedure Vulnerable_Free_Task (T : Task_Id);
- -- Recover all runtime system storage associated with the task T.
- -- This should only be called after T has terminated and will no
- -- longer be referenced.
- --
- -- For tasks created by an allocator that fails, due to an exception,
- -- it is called from Expunge_Unactivated_Tasks.
+ -- Recover all runtime system storage associated with the task T. This
+ -- should only be called after T has terminated and will no longer be
+ -- referenced.
--
- -- It is also called from Unchecked_Deallocation, for objects that
- -- are or contain tasks.
+ -- For tasks created by an allocator that fails, due to an exception, it is
+ -- called from Expunge_Unactivated_Tasks.
--
-- Different code is used at master completion, in Terminate_Dependents,
-- due to a need for tighter synchronization with the master.
begin
C := All_Tasks_List;
-
while C /= null loop
P := C.Common.Parent;
-
while P /= null loop
if P = Self_ID then
+
-- ??? C is supposed to take care of its own dependents, so
-- there should be no need to worry about them. Need to double
-- check this.
-- Activate_Tasks --
--------------------
- -- Note that locks of activator and activated task are both locked
- -- here. This is necessary because C.Common.State and
- -- Self.Common.Wait_Count have to be synchronized. This is safe from
- -- deadlock because the activator is always created before the activated
- -- task. That satisfies our in-order-of-creation ATCB locking policy.
-
- -- At one point, we may also lock the parent, if the parent is
- -- different from the activator. That is also consistent with the
- -- lock ordering policy, since the activator cannot be created
- -- before the parent.
-
- -- Since we are holding both the activator's lock, and Task_Wrapper
- -- locks that before it does anything more than initialize the
- -- low-level ATCB components, it should be safe to wait to update
- -- the counts until we see that the thread creation is successful.
-
- -- If the thread creation fails, we do need to close the entries
- -- of the task. The first phase, of dequeuing calls, only requires
- -- locking the acceptor's ATCB, but the waking up of the callers
- -- requires locking the caller's ATCB. We cannot safely do this
- -- while we are holding other locks. Therefore, the queue-clearing
- -- operation is done in a separate pass over the activation chain.
+ -- Note that locks of activator and activated task are both locked here.
+ -- This is necessary because C.Common.State and Self.Common.Wait_Count have
+ -- to be synchronized. This is safe from deadlock because the activator is
+ -- always created before the activated task. That satisfies our
+ -- in-order-of-creation ATCB locking policy.
+
+ -- At one point, we may also lock the parent, if the parent is different
+ -- from the activator. That is also consistent with the lock ordering
+ -- policy, since the activator cannot be created before the parent.
+
+ -- Since we are holding both the activator's lock, and Task_Wrapper locks
+ -- that before it does anything more than initialize the low-level ATCB
+ -- components, it should be safe to wait to update the counts until we see
+ -- that the thread creation is successful.
+
+ -- If the thread creation fails, we do need to close the entries of the
+ -- task. The first phase, of dequeuing calls, only requires locking the
+ -- acceptor's ATCB, but the waking up of the callers requires locking the
+ -- caller's ATCB. We cannot safely do this while we are holding other
+ -- locks. Therefore, the queue-clearing operation is done in a separate
+ -- pass over the activation chain.
procedure Activate_Tasks (Chain_Access : Activation_Chain_Access) is
Self_ID : constant Task_Id := STPO.Self;
All_Elaborated : Boolean := True;
begin
+ -- If pragma Detect_Blocking is active, then we must check whether this
+ -- potentially blocking operation is called from a protected action.
+
+ if System.Tasking.Detect_Blocking
+ and then Self_ID.Common.Protected_Action_Nesting > 0
+ then
+ raise Program_Error with "potentially blocking operation";
+ end if;
+
pragma Debug
(Debug.Trace (Self_ID, "Activate_Tasks", 'C'));
pragma Assert (Self_ID.Common.Wait_Count = 0);
- -- Lock RTS_Lock, to prevent activated tasks
- -- from racing ahead before we finish activating the chain.
+ -- Lock RTS_Lock, to prevent activated tasks from racing ahead before
+ -- we finish activating the chain.
Lock_RTS;
- -- Check that all task bodies have been elaborated.
+ -- Check that all task bodies have been elaborated
C := Chain_Access.T_ID;
Last_C := null;
-
while C /= null loop
if C.Common.Elaborated /= null
and then not C.Common.Elaborated.all
All_Elaborated := False;
end if;
- -- Reverse the activation chain so that tasks are
- -- activated in the same order they're declared.
+ -- Reverse the activation chain so that tasks are activated in the
+ -- same order they're declared.
Next_C := C.Common.Activation_Link;
C.Common.Activation_Link := Last_C;
if not All_Elaborated then
Unlock_RTS;
Initialization.Undefer_Abort_Nestable (Self_ID);
- Raise_Exception
- (Program_Error'Identity, "Some tasks have not been elaborated");
+ raise Program_Error with "Some tasks have not been elaborated";
end if;
- -- Activate all the tasks in the chain.
- -- Creation of the thread of control was deferred until
- -- activation. So create it now.
+ -- Activate all the tasks in the chain. Creation of the thread of
+ -- control was deferred until activation. So create it now.
C := Chain_Access.T_ID;
-
while C /= null loop
if C.Common.State /= Terminated then
pragma Assert (C.Common.State = Unactivated);
(C.Common.Compiler_Data.Pri_Stack_Info.Size),
Activate_Prio, Success);
- -- There would be a race between the created task and the
- -- creator to do the following initialization, if we did not
- -- have a Lock/Unlock_RTS pair in the task wrapper to prevent
- -- it from racing ahead.
+ -- There would be a race between the created task and the creator
+ -- to do the following initialization, if we did not have a
+ -- Lock/Unlock_RTS pair in the task wrapper to prevent it from
+ -- racing ahead.
if Success then
C.Common.State := Runnable;
Unlock_RTS;
end if;
- -- Close the entries of any tasks that failed thread creation,
- -- and count those that have not finished activation.
+ -- Close the entries of any tasks that failed thread creation, and count
+ -- those that have not finished activation.
Write_Lock (Self_ID);
Self_ID.Common.State := Activator_Sleep;
- C := Chain_Access.T_ID;
+ C := Chain_Access.T_ID;
while C /= null loop
Write_Lock (C);
-- unsafe to abort any of these tasks until the count goes to zero.
loop
- Initialization.Poll_Base_Priority_Change (Self_ID);
exit when Self_ID.Common.Wait_Count = 0;
Sleep (Self_ID, Activator_Sleep);
end loop;
if Self_ID.Common.Activation_Failed then
Self_ID.Common.Activation_Failed := False;
- Raise_Exception (Tasking_Error'Identity,
- "Failure during activation");
+ raise Tasking_Error with "Failure during activation";
end if;
end Activate_Tasks;
procedure Complete_Activation is
Self_ID : constant Task_Id := STPO.Self;
+
begin
Initialization.Defer_Abort_Nestable (Self_ID);
Initialization.Undefer_Abort_Nestable (Self_ID);
- -- ???
- -- Why do we need to allow for nested deferral here?
+ -- ??? Why do we need to allow for nested deferral here?
if Runtime_Traces then
Send_Trace_Info (T_Activate);
procedure Complete_Master is
Self_ID : constant Task_Id := STPO.Self;
-
begin
- pragma Assert (Self_ID.Deferral_Level > 0);
-
+ pragma Assert
+ (Self_ID.Deferral_Level > 0
+ or else not System.Restrictions.Abort_Allowed);
Vulnerable_Complete_Master (Self_ID);
end Complete_Master;
procedure Complete_Task is
Self_ID : constant Task_Id := STPO.Self;
+
begin
- pragma Assert (Self_ID.Deferral_Level > 0);
+ pragma Assert
+ (Self_ID.Deferral_Level > 0
+ or else not System.Restrictions.Abort_Allowed);
Vulnerable_Complete_Task (Self_ID);
-- Create_Task --
-----------------
- -- Compiler interface only. Do not call from within the RTS.
- -- This must be called to create a new task.
+ -- Compiler interface only. Do not call from within the RTS. This must be
+ -- called to create a new task.
procedure Create_Task
- (Priority : Integer;
- Size : System.Parameters.Size_Type;
- Task_Info : System.Task_Info.Task_Info_Type;
- Num_Entries : Task_Entry_Index;
- Master : Master_Level;
- State : Task_Procedure_Access;
- Discriminants : System.Address;
- Elaborated : Access_Boolean;
- Chain : in out Activation_Chain;
- Task_Image : String;
- Created_Task : out Task_Id)
+ (Priority : Integer;
+ Size : System.Parameters.Size_Type;
+ Task_Info : System.Task_Info.Task_Info_Type;
+ Relative_Deadline : Ada.Real_Time.Time_Span;
+ Num_Entries : Task_Entry_Index;
+ Master : Master_Level;
+ State : Task_Procedure_Access;
+ Discriminants : System.Address;
+ Elaborated : Access_Boolean;
+ Chain : in out Activation_Chain;
+ Task_Image : String;
+ Created_Task : out Task_Id;
+ Build_Entry_Names : Boolean)
is
T, P : Task_Id;
Self_ID : constant Task_Id := STPO.Self;
Base_Priority : System.Any_Priority;
Len : Natural;
+ pragma Unreferenced (Relative_Deadline);
+ -- EDF scheduling is not supported by any of the target platforms so
+ -- this parameter is not passed any further.
+
begin
+ -- If Master is greater than the current master, it means that Master
+ -- has already awaited its dependent tasks. This raises Program_Error,
+ -- by 4.8(10.3/2). See AI-280. Ignore this check for foreign threads.
+
+ if Self_ID.Master_of_Task /= Foreign_Task_Level
+ and then Master > Self_ID.Master_Within
+ then
+ raise Program_Error with
+ "create task after awaiting termination";
+ end if;
+
+ -- If pragma Detect_Blocking is active must be checked whether this
+ -- potentially blocking operation is called from a protected action.
+
+ if System.Tasking.Detect_Blocking
+ and then Self_ID.Common.Protected_Action_Nesting > 0
+ then
+ raise Program_Error with "potentially blocking operation";
+ end if;
+
pragma Debug
(Debug.Trace (Self_ID, "Create_Task", 'C'));
begin
T := New_ATCB (Num_Entries);
-
exception
when others =>
Initialization.Undefer_Abort_Nestable (Self_ID);
- Raise_Exception (Storage_Error'Identity, "Cannot allocate task");
+ raise Storage_Error with "Cannot allocate task";
end;
- -- RTS_Lock is used by Abort_Dependents and Abort_Tasks.
- -- Up to this point, it is possible that we may be part of
- -- a family of tasks that is being aborted.
+ -- RTS_Lock is used by Abort_Dependents and Abort_Tasks. Up to this
+ -- point, it is possible that we may be part of a family of tasks that
+ -- is being aborted.
Lock_RTS;
Write_Lock (Self_ID);
- -- Now, we must check that we have not been aborted.
- -- If so, we should give up on creating this task,
- -- and simply return.
+ -- Now, we must check that we have not been aborted. If so, we should
+ -- give up on creating this task, and simply return.
if not Self_ID.Callable then
pragma Assert (Self_ID.Pending_ATC_Level = 0);
pragma Assert (Self_ID.Pending_Action);
- pragma Assert (Chain.T_ID = null
- or else Chain.T_ID.Common.State = Unactivated);
+ pragma Assert
+ (Chain.T_ID = null or else Chain.T_ID.Common.State = Unactivated);
Unlock (Self_ID);
Unlock_RTS;
Unlock (Self_ID);
Unlock_RTS;
Initialization.Undefer_Abort_Nestable (Self_ID);
- Raise_Exception
- (Storage_Error'Identity, "Failed to initialize task");
+ raise Storage_Error with "Failed to initialize task";
+ end if;
+
+ if Master = Foreign_Task_Level + 2 then
+
+ -- This should not happen, except when a foreign task creates non
+ -- library-level Ada tasks. In this case, we pretend the master is
+ -- a regular library level task, otherwise the run-time will get
+ -- confused when waiting for these tasks to terminate.
+
+ T.Master_of_Task := Library_Task_Level;
+ else
+ T.Master_of_Task := Master;
end if;
- T.Master_of_Task := Master;
T.Master_Within := T.Master_of_Task + 1;
for L in T.Entry_Calls'Range loop
Len := 1;
T.Common.Task_Image (1) := Task_Image (Task_Image'First);
- for J in Task_Image'First + 1 .. Task_Image'Last loop
-
- -- Remove unwanted blank space generated by 'Image
+ -- Remove unwanted blank space generated by 'Image
+ for J in Task_Image'First + 1 .. Task_Image'Last loop
if Task_Image (J) /= ' '
or else Task_Image (J - 1) /= '('
then
Len := Len + 1;
T.Common.Task_Image (Len) := Task_Image (J);
-
exit when Len = T.Common.Task_Image'Last;
end if;
end loop;
T.Common.Task_Image_Len := Len;
end if;
+ if Build_Entry_Names then
+ T.Entry_Names :=
+ new Entry_Names_Array (1 .. Entry_Index (Num_Entries));
+ end if;
+
Unlock (Self_ID);
Unlock_RTS;
procedure Enter_Master is
Self_ID : constant Task_Id := STPO.Self;
-
begin
Self_ID.Master_Within := Self_ID.Master_Within + 1;
end Enter_Master;
-- Expunge_Unactivated_Tasks --
-------------------------------
- -- See procedure Close_Entries for the general case.
+ -- See procedure Close_Entries for the general case
procedure Expunge_Unactivated_Tasks (Chain : in out Activation_Chain) is
Self_ID : constant Task_Id := STPO.Self;
Initialization.Defer_Abort_Nestable (Self_ID);
-- ???
- -- Experimentation has shown that abort is sometimes (but not
- -- always) already deferred when this is called.
+ -- Experimentation has shown that abort is sometimes (but not always)
+ -- already deferred when this is called.
- -- That may indicate an error. Find out what is going on.
+ -- That may indicate an error. Find out what is going on
C := Chain.T_ID;
-
while C /= null loop
pragma Assert (C.Common.State = Unactivated);
---------------------------
-- ???
- -- We have a potential problem here if finalization of global
- -- objects does anything with signals or the timer server, since
- -- by that time those servers have terminated.
+ -- We have a potential problem here if finalization of global objects does
+ -- anything with signals or the timer server, since by that time those
+ -- servers have terminated.
- -- It is hard to see how that would occur.
+ -- It is hard to see how that would occur
-- However, a better solution might be to do all this finalization
-- using the global finalization chain.
procedure Finalize_Global_Tasks is
Self_ID : constant Task_Id := STPO.Self;
+
Ignore : Boolean;
+ pragma Unreferenced (Ignore);
begin
if Self_ID.Deferral_Level = 0 then
-- ???
- -- In principle, we should be able to predict whether
- -- abort is already deferred here (and it should not be deferred
- -- yet but in practice it seems Finalize_Global_Tasks is being
- -- called sometimes, from RTS code for exceptions, with abort already
- -- deferred.
+ -- In principle, we should be able to predict whether abort is
+ -- already deferred here (and it should not be deferred yet but in
+ -- practice it seems Finalize_Global_Tasks is being called sometimes,
+ -- from RTS code for exceptions, with abort already deferred.
Initialization.Defer_Abort_Nestable (Self_ID);
pragma Assert (Self_ID = Environment_Task);
-- Set Environment_Task'Callable to false to notify library-level tasks
- -- that it is waiting for them (cf 5619-003).
+ -- that it is waiting for them.
Self_ID.Callable := False;
- -- Exit level 2 master, for normal tasks in library-level packages.
+ -- Exit level 2 master, for normal tasks in library-level packages
Complete_Master;
- -- Force termination of "independent" library-level server tasks.
+ -- Force termination of "independent" library-level server tasks
Lock_RTS;
Unlock_RTS;
end if;
- -- We need to explicitely wait for the task to be terminated here
- -- because on true concurrent system, we may end this procedure
- -- before the tasks are really terminated.
+ -- We need to explicitly wait for the task to be terminated here
+ -- because on true concurrent system, we may end this procedure before
+ -- the tasks are really terminated.
Write_Lock (Self_ID);
loop
exit when Utilities.Independent_Task_Count = 0;
- -- We used to yield here, but this did not take into account
- -- low priority tasks that would cause dead lock in some cases.
- -- See 8126-020.
+ -- We used to yield here, but this did not take into account low
+ -- priority tasks that would cause dead lock in some cases (true
+ -- FIFO scheduling).
Timed_Sleep
(Self_ID, 0.01, System.OS_Primitives.Relative,
Vulnerable_Complete_Task (Self_ID);
- System.Finalization_Implementation.Finalize_Global_List;
+ -- Handle normal task termination by the environment task, but only
+ -- for the normal task termination. In the case of Abnormal and
+ -- Unhandled_Exception they must have been handled before, and the
+ -- task termination soft link must have been changed so the task
+ -- termination routine is not executed twice.
+
+ SSL.Task_Termination_Handler.all (Ada.Exceptions.Null_Occurrence);
+
+ -- Finalize the global list for controlled objects if needed
+
+ SSL.Finalize_Global_List.all;
+
+ -- Reset the soft links to non-tasking
SSL.Abort_Defer := SSL.Abort_Defer_NT'Access;
SSL.Abort_Undefer := SSL.Abort_Undefer_NT'Access;
SSL.Set_Jmpbuf_Address := SSL.Set_Jmpbuf_Address_NT'Access;
SSL.Get_Sec_Stack_Addr := SSL.Get_Sec_Stack_Addr_NT'Access;
SSL.Set_Sec_Stack_Addr := SSL.Set_Sec_Stack_Addr_NT'Access;
- SSL.Get_Exc_Stack_Addr := SSL.Get_Exc_Stack_Addr_NT'Access;
- SSL.Set_Exc_Stack_Addr := SSL.Set_Exc_Stack_Addr_NT'Access;
SSL.Check_Abort_Status := SSL.Check_Abort_Status_NT'Access;
SSL.Get_Stack_Info := SSL.Get_Stack_Info_NT'Access;
end Finalize_Global_Tasks;
+ ----------------------
+ -- Free_Entry_Names --
+ ----------------------
+
+ procedure Free_Entry_Names (T : Task_Id) is
+ Names : Entry_Names_Array_Access := T.Entry_Names;
+
+ procedure Free_Entry_Names_Array_Access is new
+ Ada.Unchecked_Deallocation
+ (Entry_Names_Array, Entry_Names_Array_Access);
+
+ begin
+ if Names = null then
+ return;
+ end if;
+
+ Free_Entry_Names_Array (Names.all);
+ Free_Entry_Names_Array_Access (Names);
+ end Free_Entry_Names;
+
---------------
-- Free_Task --
---------------
Initialization.Task_Lock (Self_Id);
Lock_RTS;
+ Initialization.Finalize_Attributes_Link.all (T);
Initialization.Remove_From_All_Tasks_List (T);
Unlock_RTS;
Initialization.Task_Unlock (Self_Id);
+ Free_Entry_Names (T);
System.Task_Primitives.Operations.Finalize_TCB (T);
-- If the task is not terminated, then we simply ignore the call. This
end if;
end Free_Task;
+ ---------------------------
+ -- Move_Activation_Chain --
+ ---------------------------
+
+ procedure Move_Activation_Chain
+ (From, To : Activation_Chain_Access;
+ New_Master : Master_ID)
+ is
+ Self_ID : constant Task_Id := STPO.Self;
+ C : Task_Id;
+
+ begin
+ pragma Debug
+ (Debug.Trace (Self_ID, "Move_Activation_Chain", 'C'));
+
+ -- Nothing to do if From is empty, and we can check that without
+ -- deferring aborts.
+
+ C := From.all.T_ID;
+
+ if C = null then
+ return;
+ end if;
+
+ Initialization.Defer_Abort (Self_ID);
+
+ -- Loop through the From chain, changing their Master_of_Task
+ -- fields, and to find the end of the chain.
+
+ loop
+ C.Master_of_Task := New_Master;
+ exit when C.Common.Activation_Link = null;
+ C := C.Common.Activation_Link;
+ end loop;
+
+ -- Hook From in at the start of To
+
+ C.Common.Activation_Link := To.all.T_ID;
+ To.all.T_ID := From.all.T_ID;
+
+ -- Set From to empty
+
+ From.all.T_ID := null;
+
+ Initialization.Undefer_Abort (Self_ID);
+ end Move_Activation_Chain;
+
+ -- Compiler interface only. Do not call from within the RTS.
+
+ --------------------
+ -- Set_Entry_Name --
+ --------------------
+
+ procedure Set_Entry_Name
+ (T : Task_Id;
+ Pos : Task_Entry_Index;
+ Val : String_Access)
+ is
+ begin
+ pragma Assert (T.Entry_Names /= null);
+
+ T.Entry_Names (Entry_Index (Pos)) := Val;
+ end Set_Entry_Name;
+
------------------
-- Task_Wrapper --
------------------
- -- The task wrapper is a procedure that is called first for each task
- -- task body, and which in turn calls the compiler-generated task body
- -- procedure. The wrapper's main job is to do initialization for the task.
- -- It also has some locally declared objects that server as per-task local
- -- data. Task finalization is done by Complete_Task, which is called from
- -- an at-end handler that the compiler generates.
+ -- The task wrapper is a procedure that is called first for each task body
+ -- and which in turn calls the compiler-generated task body procedure.
+ -- The wrapper's main job is to do initialization for the task. It also
+ -- has some locally declared objects that serve as per-task local data.
+ -- Task finalization is done by Complete_Task, which is called from an
+ -- at-end handler that the compiler generates.
procedure Task_Wrapper (Self_ID : Task_Id) is
- use type System.Parameters.Size_Type;
use type SSE.Storage_Offset;
use System.Standard_Library;
+ use System.Stack_Usage;
+
+ Bottom_Of_Stack : aliased Integer;
+
+ Task_Alternate_Stack :
+ aliased SSE.Storage_Array (1 .. Alternate_Stack_Size);
+ -- The alternate signal stack for this task, if any
+
+ Use_Alternate_Stack : constant Boolean := Alternate_Stack_Size /= 0;
+ -- Whether to use above alternate signal stack for stack overflows
+
+ Secondary_Stack_Size :
+ constant SSE.Storage_Offset :=
+ Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size *
+ SSE.Storage_Offset (Parameters.Sec_Stack_Ratio) / 100;
+
+ Secondary_Stack : aliased SSE.Storage_Array (1 .. Secondary_Stack_Size);
+
+ pragma Warnings (Off);
+ -- Why are warnings being turned off here???
- Secondary_Stack : aliased SSE.Storage_Array
- (1 .. Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size *
- SSE.Storage_Offset (Parameters.Sec_Stack_Ratio) / 100);
Secondary_Stack_Address : System.Address := Secondary_Stack'Address;
+ -- Address of secondary stack. In the fixed secondary stack case, this
+ -- value is not modified, causing a warning, hence the bracketing with
+ -- Warnings (Off/On). But why is so much *more* bracketed???
+
+ Small_Overflow_Guard : constant := 12 * 1024;
+ -- Note: this used to be 4K, but was changed to 12K, since smaller
+ -- values resulted in segmentation faults from dynamic stack analysis.
+
+ Big_Overflow_Guard : constant := 16 * 1024;
+ Small_Stack_Limit : constant := 64 * 1024;
+ -- ??? These three values are experimental, and seems to work on most
+ -- platforms. They still need to be analyzed further. They also need
+ -- documentation, what are they???
+
+ Size : Natural :=
+ Natural (Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size);
+
+ Overflow_Guard : Natural;
+ -- Size of the overflow guard, used by dynamic stack usage analysis
+
+ pragma Warnings (On);
+
+ SEH_Table : aliased SSE.Storage_Array (1 .. 8);
+ -- Structured Exception Registration table (2 words)
+
+ procedure Install_SEH_Handler (Addr : System.Address);
+ pragma Import (C, Install_SEH_Handler, "__gnat_install_SEH_handler");
+ -- Install the SEH (Structured Exception Handling) handler
+
+ Cause : Cause_Of_Termination := Normal;
+ -- Indicates the reason why this task terminates. Normal corresponds to
+ -- a task terminating due to completing the last statement of its body,
+ -- or as a result of waiting on a terminate alternative. If the task
+ -- terminates because it is being aborted then Cause will be set to
+ -- Abnormal. If the task terminates because of an exception raised by
+ -- the execution of its task body, then Cause is set to
+ -- Unhandled_Exception.
+
+ EO : Exception_Occurrence;
+ -- If the task terminates because of an exception raised by the
+ -- execution of its task body, then EO will contain the associated
+ -- exception occurrence. Otherwise, it will contain Null_Occurrence.
+
+ TH : Termination_Handler := null;
+ -- Pointer to the protected procedure to be executed upon task
+ -- termination.
+
+ procedure Search_Fall_Back_Handler (ID : Task_Id);
+ -- Procedure that searches recursively a fall-back handler through the
+ -- master relationship. If the handler is found, its pointer is stored
+ -- in TH.
+
+ ------------------------------
+ -- Search_Fall_Back_Handler --
+ ------------------------------
+
+ procedure Search_Fall_Back_Handler (ID : Task_Id) is
+ begin
+ -- If there is a fall back handler, store its pointer for later
+ -- execution.
+
+ if ID.Common.Fall_Back_Handler /= null then
+ TH := ID.Common.Fall_Back_Handler;
+
+ -- Otherwise look for a fall back handler in the parent
+
+ elsif ID.Common.Parent /= null then
+ Search_Fall_Back_Handler (ID.Common.Parent);
+
+ -- Otherwise, do nothing
+
+ else
+ return;
+ end if;
+ end Search_Fall_Back_Handler;
begin
pragma Assert (Self_ID.Deferral_Level = 1);
+ -- Assume a size of the stack taken at this stage
+
+ if Size < Small_Stack_Limit then
+ Overflow_Guard := Small_Overflow_Guard;
+ else
+ Overflow_Guard := Big_Overflow_Guard;
+ end if;
+
if not Parameters.Sec_Stack_Dynamic then
Self_ID.Common.Compiler_Data.Sec_Stack_Addr :=
Secondary_Stack'Address;
SST.SS_Init (Secondary_Stack_Address, Integer (Secondary_Stack'Last));
+ Size := Size - Natural (Secondary_Stack_Size);
+ end if;
+
+ if Use_Alternate_Stack then
+ Self_ID.Common.Task_Alternate_Stack := Task_Alternate_Stack'Address;
end if;
- -- Set the guard page at the bottom of the stack. The call to
- -- unprotect the page is done in Terminate_Task
+ Size := Size - Overflow_Guard;
+
+ if System.Stack_Usage.Is_Enabled then
+ STPO.Lock_RTS;
+ Initialize_Analyzer
+ (Self_ID.Common.Analyzer,
+ Self_ID.Common.Task_Image
+ (1 .. Self_ID.Common.Task_Image_Len),
+ Natural
+ (Self_ID.Common.Compiler_Data.Pri_Stack_Info.Size),
+ Size,
+ SSE.To_Integer (Bottom_Of_Stack'Address));
+ STPO.Unlock_RTS;
+ Fill_Stack (Self_ID.Common.Analyzer);
+ end if;
+
+ -- Set the guard page at the bottom of the stack. The call to unprotect
+ -- the page is done in Terminate_Task
Stack_Guard (Self_ID, True);
- -- Initialize low-level TCB components, that cannot be initialized
- -- by the creator. Enter_Task sets Self_ID.Known_Tasks_Index and
- -- also Self_ID.LL.Thread
+ -- Initialize low-level TCB components, that cannot be initialized by
+ -- the creator. Enter_Task sets Self_ID.Known_Tasks_Index and also
+ -- Self_ID.LL.Thread
Enter_Task (Self_ID);
- -- We lock RTS_Lock to wait for activator to finish activating
- -- the rest of the chain, so that everyone in the chain comes out
- -- in priority order.
+ -- We setup the SEH (Structured Exception Handling) handler if supported
+ -- on the target.
+
+ Install_SEH_Handler (SEH_Table'Address);
+
+ -- Initialize exception occurrence
+
+ Save_Occurrence (EO, Ada.Exceptions.Null_Occurrence);
+
+ -- We lock RTS_Lock to wait for activator to finish activating the rest
+ -- of the chain, so that everyone in the chain comes out in priority
+ -- order.
-- This also protects the value of
-- Self_ID.Common.Activator.Common.Wait_Count.
Lock_RTS;
Unlock_RTS;
+ if not System.Restrictions.Abort_Allowed then
+
+ -- If Abort is not allowed, reset the deferral level since it will
+ -- not get changed by the generated code. Keeping a default value
+ -- of one would prevent some operations (e.g. select or delay) to
+ -- proceed successfully.
+
+ Self_ID.Deferral_Level := 0;
+ end if;
+
begin
-- We are separating the following portion of the code in order to
-- place the exception handlers in a different block. In this way,
-- clean ups associated with the exception handler that need to
-- access task specific data.
- -- Defer abortion so that this task can't be aborted while exiting
+ -- Defer abort so that this task can't be aborted while exiting
when Standard'Abort_Signal =>
Initialization.Defer_Abort_Nestable (Self_ID);
+ -- Update the cause that motivated the task termination so that
+ -- the appropriate information is passed to the task termination
+ -- procedure. Task termination as a result of waiting on a
+ -- terminate alternative is a normal termination, although it is
+ -- implemented using the abort mechanisms.
+
+ if Self_ID.Terminate_Alternative then
+ Cause := Normal;
+ else
+ Cause := Abnormal;
+ end if;
when others =>
- -- ??? Using an E : others here causes CD2C11A to fail on
- -- DEC Unix, see 7925-005.
+ -- ??? Using an E : others here causes CD2C11A to fail on Tru64
Initialization.Defer_Abort_Nestable (Self_ID);
if Exception_Trace = Unhandled_Raise then
Trace_Unhandled_Exception_In_Task (Self_ID);
end if;
+
+ -- Update the cause that motivated the task termination so that
+ -- the appropriate information is passed to the task termination
+ -- procedure, as well as the associated Exception_Occurrence.
+
+ Cause := Unhandled_Exception;
+ Save_Occurrence (EO, SSL.Get_Current_Excep.all.all);
end;
+ -- Look for a task termination handler. This code is for all tasks but
+ -- the environment task. The task termination code for the environment
+ -- task is executed by SSL.Task_Termination_Handler.
+
+ if Single_Lock then
+ Lock_RTS;
+ end if;
+
+ Write_Lock (Self_ID);
+
+ if Self_ID.Common.Specific_Handler /= null then
+ TH := Self_ID.Common.Specific_Handler;
+ else
+ -- Look for a fall-back handler following the master relationship
+ -- for the task.
+
+ Search_Fall_Back_Handler (Self_ID);
+ end if;
+
+ Unlock (Self_ID);
+
+ if Single_Lock then
+ Unlock_RTS;
+ end if;
+
+ -- Execute the task termination handler if we found it
+
+ if TH /= null then
+ TH.all (Cause, Self_ID, EO);
+ end if;
+
+ if System.Stack_Usage.Is_Enabled then
+ Compute_Result (Self_ID.Common.Analyzer);
+ Report_Result (Self_ID.Common.Analyzer);
+ end if;
+
Terminate_Task (Self_ID);
end Task_Wrapper;
--------------------
-- Before we allow the thread to exit, we must clean up. This is a
- -- a delicate job. We must wake up the task's master, who may immediately
- -- try to deallocate the ATCB out from under the current task WHILE IT IS
- -- STILL EXECUTING.
+ -- delicate job. We must wake up the task's master, who may immediately try
+ -- to deallocate the ATCB out from under the current task WHILE IT IS STILL
+ -- EXECUTING.
-- To avoid this, the parent task must be blocked up to the latest
-- statement executed. The trouble is that we have another step that we
-- We can't call Destroy_TSD while we are holding any other locks, because
-- it locks Global_Task_Lock, and our deadlock prevention rules require
-- that to be the outermost lock. Our first "solution" was to just lock
- -- Global_Task_Lock in addition to the other locks, and force the parent
- -- to also lock this lock between its wakeup and its freeing of the ATCB.
- -- See Complete_Task for the parent-side of the code that has the matching
+ -- Global_Task_Lock in addition to the other locks, and force the parent to
+ -- also lock this lock between its wakeup and its freeing of the ATCB. See
+ -- Complete_Task for the parent-side of the code that has the matching
-- calls to Task_Lock and Task_Unlock. That was not really a solution,
-- since the operation Task_Unlock continued to access the ATCB after
- -- unlocking, after which the parent was observed to race ahead,
- -- deallocate the ATCB, and then reallocate it to another task. The
- -- call to Undefer_Abortion in Task_Unlock by the "terminated" task was
- -- overwriting the data of the new task that reused the ATCB! To solve
- -- this problem, we introduced the new operation Final_Task_Unlock.
+ -- unlocking, after which the parent was observed to race ahead, deallocate
+ -- the ATCB, and then reallocate it to another task. The call to
+ -- Undefer_Abort in Task_Unlock by the "terminated" task was overwriting
+ -- the data of the new task that reused the ATCB! To solve this problem, we
+ -- introduced the new operation Final_Task_Unlock.
procedure Terminate_Task (Self_ID : Task_Id) is
Environment_Task : constant Task_Id := STPO.Environment_Task;
-- Since GCC cannot allocate stack chunks efficiently without reordering
-- some of the allocations, we have to handle this unexpected situation
-- here. We should normally never have to call Vulnerable_Complete_Task
- -- here. See 6602-003 for more details.
+ -- here.
if Self_ID.Common.Activator /= null then
Vulnerable_Complete_Task (Self_ID);
Master_of_Task := Self_ID.Master_of_Task;
- -- Check if the current task is an independent task
- -- If so, decrement the Independent_Task_Count value.
+ -- Check if the current task is an independent task If so, decrement
+ -- the Independent_Task_Count value.
- if Master_of_Task = 2 then
+ if Master_of_Task = Independent_Task_Level then
if Single_Lock then
Utilities.Independent_Task_Count :=
Utilities.Independent_Task_Count - 1;
-
else
Write_Lock (Environment_Task);
Utilities.Independent_Task_Count :=
SSL.Destroy_TSD (Self_ID.Common.Compiler_Data);
Initialization.Final_Task_Unlock (Self_ID);
- -- WARNING
- -- past this point, this thread must assume that the ATCB
- -- has been deallocated. It should not be accessed again.
+ -- WARNING: past this point, this thread must assume that the ATCB has
+ -- been deallocated. It should not be accessed again.
if Master_of_Task > 0 then
STPO.Exit_Task;
procedure To_Stderr (S : String);
pragma Import (Ada, To_Stderr, "__gnat_to_stderr");
- use System.Task_Info;
use System.Soft_Links;
use System.Standard_Library;
function To_Address is new
- Unchecked_Conversion (Task_Id, System.Address);
+ Ada.Unchecked_Conversion
+ (Task_Id, System.Task_Primitives.Task_Address);
function Tailored_Exception_Information
(E : Exception_Occurrence) return String;
-- The activator raises a Tasking_Error if any task it is activating
-- is completed before the activation is done. However, if the reason
- -- for the task completion is an abortion, we do not raise an exception.
+ -- for the task completion is an abort, we do not raise an exception.
-- See RM 9.2(5).
if not Self_ID.Callable and then Self_ID.Pending_ATC_Level /= 0 then
Unlock (Self_ID);
Unlock (Activator);
- -- After the activation, active priority should be the same
- -- as base priority. We must unlock the Activator first,
- -- though, since it should not wait if we have lower priority.
+ -- After the activation, active priority should be the same as base
+ -- priority. We must unlock the Activator first, though, since it
+ -- should not wait if we have lower priority.
if Get_Priority (Self_ID) /= Self_ID.Common.Base_Priority then
Write_Lock (Self_ID);
--------------------------------
procedure Vulnerable_Complete_Master (Self_ID : Task_Id) is
- C : Task_Id;
- P : Task_Id;
- CM : constant Master_Level := Self_ID.Master_Within;
- T : aliased Task_Id;
+ C : Task_Id;
+ P : Task_Id;
+ CM : constant Master_Level := Self_ID.Master_Within;
+ T : aliased Task_Id;
To_Be_Freed : Task_Id;
- -- This is a list of ATCBs to be freed, after we have released
- -- all RTS locks. This is necessary because of the locking order
- -- rules, since the storage manager uses Global_Task_Lock.
+ -- This is a list of ATCBs to be freed, after we have released all RTS
+ -- locks. This is necessary because of the locking order rules, since
+ -- the storage manager uses Global_Task_Lock.
pragma Warnings (Off);
function Check_Unactivated_Tasks return Boolean;
end if;
Write_Lock (Self_ID);
- C := All_Tasks_List;
+ C := All_Tasks_List;
while C /= null loop
- if C.Common.Activator = Self_ID then
+ if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then
return False;
end if;
(Debug.Trace (Self_ID, "V_Complete_Master", 'C'));
pragma Assert (Self_ID.Common.Wait_Count = 0);
- pragma Assert (Self_ID.Deferral_Level > 0);
+ pragma Assert
+ (Self_ID.Deferral_Level > 0
+ or else not System.Restrictions.Abort_Allowed);
- -- Count how many active dependent tasks this master currently
- -- has, and record this in Wait_Count.
+ -- Count how many active dependent tasks this master currently has, and
+ -- record this in Wait_Count.
- -- This count should start at zero, since it is initialized to
- -- zero for new tasks, and the task should not exit the
- -- sleep-loops that use this count until the count reaches zero.
+ -- This count should start at zero, since it is initialized to zero for
+ -- new tasks, and the task should not exit the sleep-loops that use this
+ -- count until the count reaches zero.
+
+ -- While we're counting, if we run across any unactivated tasks that
+ -- belong to this master, we summarily terminate them as required by
+ -- RM-9.2(6).
Lock_RTS;
Write_Lock (Self_ID);
- C := All_Tasks_List;
+ C := All_Tasks_List;
while C /= null loop
- if C.Common.Activator = Self_ID then
+
+ -- Terminate unactivated (never-to-be activated) tasks
+
+ if C.Common.Activator = Self_ID and then C.Master_of_Task = CM then
+
pragma Assert (C.Common.State = Unactivated);
+ -- Usually, C.Common.Activator = Self_ID implies C.Master_of_Task
+ -- = CM. The only case where C is pending activation by this
+ -- task, but the master of C is not CM is in Ada 2005, when C is
+ -- part of a return object of a build-in-place function.
Write_Lock (C);
C.Common.Activator := null;
Unlock (C);
end if;
+ -- Count it if dependent on this master
+
if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
Write_Lock (C);
-- Wait until dependent tasks are all terminated or ready to terminate.
-- While waiting, the task may be awakened if the task's priority needs
- -- changing, or this master is aborted. In the latter case, we want
- -- to abort the dependents, and resume waiting until Wait_Count goes
- -- to zero.
+ -- changing, or this master is aborted. In the latter case, we abort the
+ -- dependents, and resume waiting until Wait_Count goes to zero.
Write_Lock (Self_ID);
loop
- Initialization.Poll_Base_Priority_Change (Self_ID);
exit when Self_ID.Common.Wait_Count = 0;
-- Here is a difference as compared to Complete_Master
Self_ID.Common.State := Runnable;
Unlock (Self_ID);
- -- Dependents are all terminated or on terminate alternatives.
- -- Now, force those on terminate alternatives to terminate, by
- -- aborting them.
+ -- Dependents are all terminated or on terminate alternatives. Now,
+ -- force those on terminate alternatives to terminate, by aborting them.
pragma Assert (Check_Unactivated_Tasks);
pragma Assert (Self_ID.Common.Wait_Count = 0);
- -- Force any remaining dependents to terminate, by aborting them.
+ -- Force any remaining dependents to terminate by aborting them
if not Single_Lock then
Lock_RTS;
-- rules prevent us from doing that without releasing the locks on C
-- and Self_ID. Releasing and retaking those locks would be wasteful
-- at best, and should not be considered further without more
- -- detailed analysis of potential concurrent accesses to the
- -- ATCBs of C and Self_ID.
+ -- detailed analysis of potential concurrent accesses to the ATCBs
+ -- of C and Self_ID.
- -- Count how many "alive" dependent tasks this master currently
- -- has, and record this in Wait_Count. This count should start at
- -- zero, since it is initialized to zero for new tasks, and the
- -- task should not exit the sleep-loops that use this count until
- -- the count reaches zero.
+ -- Count how many "alive" dependent tasks this master currently has,
+ -- and record this in Wait_Count. This count should start at zero,
+ -- since it is initialized to zero for new tasks, and the task should
+ -- not exit the sleep-loops that use this count until the count
+ -- reaches zero.
pragma Assert (Self_ID.Common.Wait_Count = 0);
Write_Lock (Self_ID);
- C := All_Tasks_List;
+ C := All_Tasks_List;
while C /= null loop
if C.Common.Parent = Self_ID and then C.Master_of_Task = CM then
Write_Lock (C);
Unlock_RTS;
end if;
- -- Wait for all counted tasks to finish terminating themselves.
+ -- Wait for all counted tasks to finish terminating themselves
Write_Lock (Self_ID);
loop
- Initialization.Poll_Base_Priority_Change (Self_ID);
exit when Self_ID.Common.Wait_Count = 0;
Sleep (Self_ID, Master_Phase_2_Sleep);
end loop;
Unlock (Self_ID);
end if;
- -- We don't wake up for abortion here. We are already terminating
- -- just as fast as we can, so there is no point.
+ -- We don't wake up for abort here. We are already terminating just as
+ -- fast as we can, so there is no point.
-- Remove terminated tasks from the list of Self_ID's dependents, but
- -- don't free their ATCBs yet, because of lock order restrictions,
- -- which don't allow us to call "free" or "malloc" while holding any
- -- other locks. Instead, we put those ATCBs to be freed onto a
- -- temporary list, called To_Be_Freed.
+ -- don't free their ATCBs yet, because of lock order restrictions, which
+ -- don't allow us to call "free" or "malloc" while holding any other
+ -- locks. Instead, we put those ATCBs to be freed onto a temporary list,
+ -- called To_Be_Freed.
if not Single_Lock then
Lock_RTS;
C := All_Tasks_List;
P := null;
-
while C /= null loop
if C.Common.Parent = Self_ID and then C.Master_of_Task >= CM then
if P /= null then
Unlock_RTS;
- -- Free all the ATCBs on the list To_Be_Freed.
+ -- Free all the ATCBs on the list To_Be_Freed
-- The ATCBs in the list are no longer in All_Tasks_List, and after
-- any interrupt entries are detached from them they should no longer
-- ???
-- The check "T.Common.Parent /= null ..." below is to prevent dangling
- -- references to terminated library-level tasks, which could
- -- otherwise occur during finalization of library-level objects.
- -- A better solution might be to hook task objects into the
- -- finalization chain and deallocate the ATCB when the task
- -- object is deallocated. However, this change is not likely
- -- to gain anything significant, since all this storage should
- -- be recovered en-masse when the process exits.
+ -- references to terminated library-level tasks, which could otherwise
+ -- occur during finalization of library-level objects. A better solution
+ -- might be to hook task objects into the finalization chain and
+ -- deallocate the ATCB when the task object is deallocated. However,
+ -- this change is not likely to gain anything significant, since all
+ -- this storage should be recovered en-masse when the process exits.
while To_Be_Freed /= null loop
T := To_Be_Freed;
if (T.Common.Parent /= null
and then T.Common.Parent.Common.Parent /= null)
- or else T.Master_of_Task > 3
+ or else T.Master_of_Task > Library_Task_Level
then
Initialization.Task_Lock (Self_ID);
-- ATCB. That would not cover the case of unactivated tasks. It also
-- would force us to keep the underlying thread around past termination,
-- since references to the ATCB are possible past termination.
+
-- Currently, we get rid of the thread as soon as the task terminates,
-- and let the parent recover the ATCB later.
-- that no longer have ATCBs. It is not clear how much this would gain,
-- since the user-level task object would still be occupying storage.
- -- Make next master level up active.
- -- We don't need to lock the ATCB, since the value is only updated by
- -- each task for itself.
+ -- Make next master level up active. We don't need to lock the ATCB,
+ -- since the value is only updated by each task for itself.
Self_ID.Master_Within := CM - 1;
end Vulnerable_Complete_Master;
-- Complete the calling task
- -- This procedure must be called with abort deferred. (That's why the
- -- name has "Vulnerable" in it.) It should only be called by Complete_Task
- -- and Finalize_Global_Tasks (for the environment task).
+ -- This procedure must be called with abort deferred. It should only be
+ -- called by Complete_Task and Finalize_Global_Tasks (for the environment
+ -- task).
-- The effect is similar to that of Complete_Master. Differences include
-- the closing of entries here, and computation of the number of active
procedure Vulnerable_Complete_Task (Self_ID : Task_Id) is
begin
- pragma Assert (Self_ID.Deferral_Level > 0);
+ pragma Assert
+ (Self_ID.Deferral_Level > 0
+ or else not System.Restrictions.Abort_Allowed);
pragma Assert (Self_ID = Self);
pragma Assert (Self_ID.Master_Within = Self_ID.Master_of_Task + 1
or else
Unlock_RTS;
end if;
- -- If Self_ID.Master_Within = Self_ID.Master_of_Task + 2
- -- we may have dependent tasks for which we need to wait.
- -- Otherwise, we can just exit.
+ -- If Self_ID.Master_Within = Self_ID.Master_of_Task + 2 we may have
+ -- dependent tasks for which we need to wait. Otherwise we just exit.
if Self_ID.Master_Within = Self_ID.Master_of_Task + 2 then
Vulnerable_Complete_Master (Self_ID);
-- Vulnerable_Free_Task --
--------------------------
- -- Recover all runtime system storage associated with the task T.
- -- This should only be called after T has terminated and will no
- -- longer be referenced.
+ -- Recover all runtime system storage associated with the task T. This
+ -- should only be called after T has terminated and will no longer be
+ -- referenced.
- -- For tasks created by an allocator that fails, due to an exception,
- -- it is called from Expunge_Unactivated_Tasks.
+ -- For tasks created by an allocator that fails, due to an exception, it
+ -- is called from Expunge_Unactivated_Tasks.
- -- For tasks created by elaboration of task object declarations it
- -- is called from the finalization code of the Task_Wrapper procedure.
- -- It is also called from Unchecked_Deallocation, for objects that
- -- are or contain tasks.
+ -- For tasks created by elaboration of task object declarations it is
+ -- called from the finalization code of the Task_Wrapper procedure. It is
+ -- also called from Ada.Unchecked_Deallocation, for objects that are or
+ -- contain tasks.
procedure Vulnerable_Free_Task (T : Task_Id) is
begin
Unlock_RTS;
end if;
+ Free_Entry_Names (T);
System.Task_Primitives.Operations.Finalize_TCB (T);
end Vulnerable_Free_Task;
+-- Package elaboration code
+
begin
- -- Establish the Adafinal softlink.
+ -- Establish the Adafinal oftlink
-- This is not done inside the central RTS initialization routine
-- to avoid with-ing this package from System.Tasking.Initialization.
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