+++ /dev/null
-------------------------------------------------------------------------------
--- --
--- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
--- --
--- S Y S T E M . T A S K I N G . R E N D E Z V O U S --
--- --
--- B o d y --
--- --
--- $Revision: 1.1 $
--- --
--- Copyright (C) 1991-2001, Florida State University --
--- --
--- 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- --
--- 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. --
--- --
--- 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. --
--- --
--- GNARL was developed by the GNARL team at Florida State University. It is --
--- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
--- State University (http://www.gnat.com). --
--- --
-------------------------------------------------------------------------------
-
-with Ada.Exceptions;
--- Used for Exception_ID
--- Null_Id
--- Save_Occurrence
--- Raise_Exception
-
-with System.Task_Primitives.Operations;
--- used for Get_Priority
--- Set_Priority
--- Write_Lock
--- Unlock
--- Sleep
--- Wakeup
--- Timed_Sleep
-
-with System.Tasking.Entry_Calls;
--- Used for Wait_For_Completion
--- Wait_For_Completion_With_Timeout
--- Wait_Until_Abortable
-
-with System.Tasking.Initialization;
--- used for Defer_Abort
--- Undefer_Abort
--- Poll_Base_Priority_Change
-
-with System.Tasking.Queuing;
--- used for Enqueue
--- Dequeue_Head
--- Select_Task_Entry_Call
--- Count_Waiting
-
-with System.Tasking.Utilities;
--- used for Check_Exception
--- Make_Passive
--- Wakeup_Entry_Caller
-
-with System.Tasking.Protected_Objects.Operations;
--- used for PO_Do_Or_Queue
--- PO_Service_Entries
--- Lock_Entries
--- Unlock_Entries
-
-with System.Tasking.Debug;
--- used for Trace
-
-package body System.Tasking.Rendezvous is
-
- package STPO renames System.Task_Primitives.Operations;
- package POO renames System.Tasking.Protected_Objects.Operations;
- package POE renames System.Tasking.Protected_Objects.Entries;
-
- use System.Task_Primitives;
- use System.Task_Primitives.Operations;
-
- type Select_Treatment is (
- Accept_Alternative_Selected, -- alternative with non-null body
- Accept_Alternative_Completed, -- alternative with null body
- Else_Selected,
- Terminate_Selected,
- Accept_Alternative_Open,
- No_Alternative_Open);
-
- Default_Treatment : constant array (Select_Modes) of Select_Treatment :=
- (Simple_Mode => No_Alternative_Open,
- Else_Mode => Else_Selected,
- Terminate_Mode => Terminate_Selected,
- Delay_Mode => No_Alternative_Open);
-
- New_State : constant array (Boolean, Entry_Call_State)
- of Entry_Call_State :=
- (True =>
- (Never_Abortable => Never_Abortable,
- Not_Yet_Abortable => Now_Abortable,
- Was_Abortable => Now_Abortable,
- Now_Abortable => Now_Abortable,
- Done => Done,
- Cancelled => Cancelled),
- False =>
- (Never_Abortable => Never_Abortable,
- Not_Yet_Abortable => Not_Yet_Abortable,
- Was_Abortable => Was_Abortable,
- Now_Abortable => Now_Abortable,
- Done => Done,
- Cancelled => Cancelled)
- );
-
- -----------------------
- -- Local Subprograms --
- -----------------------
-
- procedure Local_Defer_Abort (Self_Id : Task_ID) renames
- System.Tasking.Initialization.Defer_Abort_Nestable;
-
- procedure Local_Undefer_Abort (Self_Id : Task_ID) renames
- System.Tasking.Initialization.Undefer_Abort_Nestable;
-
- -- Florist defers abort around critical sections that
- -- make entry calls to the Interrupt_Manager task, which
- -- violates the general rule about top-level runtime system
- -- calls from abort-deferred regions. It is not that this is
- -- unsafe, but when it occurs in "normal" programs it usually
- -- means either the user is trying to do a potentially blocking
- -- operation from within a protected object, or there is a
- -- runtime system/compiler error that has failed to undefer
- -- an earlier abort deferral. Thus, for debugging it may be
- -- wise to modify the above renamings to the non-nestable forms.
-
- procedure Boost_Priority
- (Call : Entry_Call_Link;
- Acceptor : Task_ID);
- pragma Inline (Boost_Priority);
- -- Call this only with abort deferred and holding lock of Acceptor.
-
- procedure Call_Synchronous
- (Acceptor : Task_ID;
- E : Task_Entry_Index;
- Uninterpreted_Data : System.Address;
- Mode : Call_Modes;
- Rendezvous_Successful : out Boolean);
- pragma Inline (Call_Synchronous);
- -- This call is used to make a simple or conditional entry call.
-
- procedure Setup_For_Rendezvous_With_Body
- (Entry_Call : Entry_Call_Link;
- Acceptor : Task_ID);
- pragma Inline (Setup_For_Rendezvous_With_Body);
- -- Call this only with abort deferred and holding lock of Acceptor.
- -- When a rendezvous selected (ready for rendezvous) we need to save
- -- privious caller and adjust the priority. Also we need to make
- -- this call not Abortable (Cancellable) since the rendezvous has
- -- already been started.
-
- function Is_Entry_Open (T : Task_ID; E : Task_Entry_Index) return Boolean;
- pragma Inline (Is_Entry_Open);
- -- Call this only with abort deferred and holding lock of T.
-
- procedure Wait_For_Call (Self_Id : Task_ID);
- pragma Inline (Wait_For_Call);
- -- Call this only with abort deferred and holding lock of Self_Id.
- -- An accepting task goes into Sleep by calling this routine
- -- waiting for a call from the caller or waiting for an abortion.
- -- Make sure Self_Id is locked before calling this routine.
-
- -----------------
- -- Accept_Call --
- -----------------
-
- -- Compiler interface only. Do not call from within the RTS.
-
- -- source:
- -- accept E do ...A... end E;
- -- expansion:
- -- A27b : address;
- -- L26b : label
- -- begin
- -- accept_call (1, A27b);
- -- ...A...
- -- complete_rendezvous;
- -- <<L26b>>
- -- exception
- -- when all others =>
- -- exceptional_complete_rendezvous (get_gnat_exception);
- -- end;
-
- -- The handler for Abort_Signal (*all* others) is to handle the case when
- -- the acceptor is aborted between Accept_Call and the corresponding
- -- Complete_Rendezvous call. We need to wake up the caller in this case.
-
- -- See also Selective_Wait
-
- procedure Accept_Call
- (E : Task_Entry_Index;
- Uninterpreted_Data : out System.Address)
- is
- Self_Id : constant Task_ID := STPO.Self;
- Caller : Task_ID := null;
- Open_Accepts : aliased Accept_List (1 .. 1);
- Entry_Call : Entry_Call_Link;
-
- begin
- Initialization.Defer_Abort (Self_Id);
-
- STPO.Write_Lock (Self_Id);
-
- if not Self_Id.Callable then
- pragma Assert (Self_Id.Pending_ATC_Level = 0);
-
- pragma Assert (Self_Id.Pending_Action);
-
- STPO.Unlock (Self_Id);
- Initialization.Undefer_Abort (Self_Id);
-
- -- Should never get here ???
-
- pragma Assert (False);
- raise Standard'Abort_Signal;
- end if;
-
- -- If someone completed this task, this task should not try to
- -- access its pending entry calls or queues in this case, as they
- -- are being emptied. Wait for abortion to kill us.
- -- ?????
- -- Recheck the correctness of the above, now that we have made
- -- changes. The logic above seems to be based on the assumption
- -- that one task can safely clean up another's in-service accepts.
- -- ?????
- -- Why do we need to block here in this case?
- -- Why not just return and let Undefer_Abort do its work?
-
- Queuing.Dequeue_Head (Self_Id.Entry_Queues (E), Entry_Call);
-
- if Entry_Call /= null then
- Caller := Entry_Call.Self;
- Setup_For_Rendezvous_With_Body (Entry_Call, Self_Id);
- Uninterpreted_Data := Entry_Call.Uninterpreted_Data;
-
- else
- -- Wait for a caller
-
- Open_Accepts (1).Null_Body := False;
- Open_Accepts (1).S := E;
- Self_Id.Open_Accepts := Open_Accepts'Unrestricted_Access;
-
- -- Wait for normal call
-
- pragma Debug
- (Debug.Trace (Self_Id, "Accept_Call: wait", 'R'));
- Wait_For_Call (Self_Id);
-
- pragma Assert (Self_Id.Open_Accepts = null);
-
- if Self_Id.Pending_ATC_Level >= Self_Id.ATC_Nesting_Level then
- Caller := Self_Id.Common.Call.Self;
- Uninterpreted_Data :=
- Caller.Entry_Calls (Caller.ATC_Nesting_Level).Uninterpreted_Data;
- end if;
-
- -- If this task has been aborted, skip the Uninterpreted_Data load
- -- (Caller will not be reliable) and fall through to
- -- Undefer_Abort which will allow the task to be killed.
- -- ?????
- -- Perhaps we could do the code anyway, if it has no harm, in order
- -- to get better performance for the normal case.
-
- end if;
-
- -- Self_Id.Common.Call should already be updated by the Caller
- -- On return, we will start the rendezvous.
-
- STPO.Unlock (Self_Id);
- Initialization.Undefer_Abort (Self_Id);
- end Accept_Call;
-
- --------------------
- -- Accept_Trivial --
- --------------------
-
- -- Compiler interface only. Do not call from within the RTS.
- -- This should only be called when there is no accept body,
- -- or the except body is empty.
-
- -- source:
- -- accept E;
- -- expansion:
- -- accept_trivial (1);
-
- -- The compiler is also able to recognize the following and
- -- translate it the same way.
-
- -- accept E do null; end E;
-
- procedure Accept_Trivial (E : Task_Entry_Index) is
- Self_Id : constant Task_ID := STPO.Self;
- Caller : Task_ID := null;
- Open_Accepts : aliased Accept_List (1 .. 1);
- Entry_Call : Entry_Call_Link;
-
- begin
- Initialization.Defer_Abort_Nestable (Self_Id);
- STPO.Write_Lock (Self_Id);
-
- if not Self_Id.Callable then
- pragma Assert (Self_Id.Pending_ATC_Level = 0);
-
- pragma Assert (Self_Id.Pending_Action);
-
- STPO.Unlock (Self_Id);
- Initialization.Undefer_Abort_Nestable (Self_Id);
-
- -- Should never get here ???
-
- pragma Assert (False);
- raise Standard'Abort_Signal;
- end if;
-
- -- If someone completed this task, this task should not try to
- -- access its pending entry calls or queues in this case, as they
- -- are being emptied. Wait for abortion to kill us.
- -- ?????
- -- Recheck the correctness of the above, now that we have made
- -- changes.
-
- Queuing.Dequeue_Head (Self_Id.Entry_Queues (E), Entry_Call);
-
- if Entry_Call = null then
-
- -- Need to wait for entry call
-
- Open_Accepts (1).Null_Body := True;
- Open_Accepts (1).S := E;
- Self_Id.Open_Accepts := Open_Accepts'Unrestricted_Access;
-
- pragma Debug
- (Debug.Trace (Self_Id, "Accept_Trivial: wait", 'R'));
-
- Wait_For_Call (Self_Id);
-
- pragma Assert (Self_Id.Open_Accepts = null);
-
- -- No need to do anything special here for pending abort.
- -- Abort_Signal will be raised by Undefer on exit.
-
- STPO.Unlock (Self_Id);
-
- else -- found caller already waiting
-
- pragma Assert (Entry_Call.State < Done);
-
- STPO.Unlock (Self_Id);
- Caller := Entry_Call.Self;
-
- STPO.Write_Lock (Caller);
- Initialization.Wakeup_Entry_Caller (Self_Id, Entry_Call, Done);
- STPO.Unlock (Caller);
- end if;
-
- Initialization.Undefer_Abort_Nestable (Self_Id);
- end Accept_Trivial;
-
- --------------------
- -- Boost_Priority --
- --------------------
-
- -- Call this only with abort deferred and holding lock of Acceptor.
-
- procedure Boost_Priority (Call : Entry_Call_Link; Acceptor : Task_ID) is
- Caller : Task_ID := Call.Self;
- Caller_Prio : System.Any_Priority := Get_Priority (Caller);
- Acceptor_Prio : System.Any_Priority := Get_Priority (Acceptor);
-
- begin
- if Caller_Prio > Acceptor_Prio then
- Call.Acceptor_Prev_Priority := Acceptor_Prio;
- Set_Priority (Acceptor, Caller_Prio);
-
- else
- Call.Acceptor_Prev_Priority := Priority_Not_Boosted;
- end if;
- end Boost_Priority;
-
- -----------------
- -- Call_Simple --
- -----------------
-
- -- Compiler interface only. Do not call from within the RTS.
-
- procedure Call_Simple
- (Acceptor : Task_ID;
- E : Task_Entry_Index;
- Uninterpreted_Data : System.Address)
- is
- Rendezvous_Successful : Boolean;
- begin
- Call_Synchronous
- (Acceptor, E, Uninterpreted_Data, Simple_Call, Rendezvous_Successful);
- end Call_Simple;
-
- ----------------------
- -- Call_Synchronous --
- ----------------------
-
- -- Compiler interface.
- -- Also called from inside Call_Simple and Task_Entry_Call.
-
- procedure Call_Synchronous
- (Acceptor : Task_ID;
- E : Task_Entry_Index;
- Uninterpreted_Data : System.Address;
- Mode : Call_Modes;
- Rendezvous_Successful : out Boolean)
- is
- Self_Id : constant Task_ID := STPO.Self;
- Level : ATC_Level;
- Entry_Call : Entry_Call_Link;
-
- begin
- pragma Assert (Mode /= Asynchronous_Call);
-
- Local_Defer_Abort (Self_Id);
- Self_Id.ATC_Nesting_Level := Self_Id.ATC_Nesting_Level + 1;
- pragma Debug
- (Debug.Trace (Self_Id, "CS: entered ATC level: " &
- ATC_Level'Image (Self_Id.ATC_Nesting_Level), 'A'));
- Level := Self_Id.ATC_Nesting_Level;
- Entry_Call := Self_Id.Entry_Calls (Level)'Access;
- Entry_Call.Next := null;
- Entry_Call.Mode := Mode;
- Entry_Call.Cancellation_Attempted := False;
-
- -- If this is a call made inside of an abort deferred region,
- -- the call should be never abortable.
-
- if Self_Id.Deferral_Level > 1 then
- Entry_Call.State := Never_Abortable;
- else
- Entry_Call.State := Now_Abortable;
- end if;
-
- Entry_Call.E := Entry_Index (E);
- Entry_Call.Prio := Get_Priority (Self_Id);
- Entry_Call.Uninterpreted_Data := Uninterpreted_Data;
- Entry_Call.Called_Task := Acceptor;
- Entry_Call.Exception_To_Raise := Ada.Exceptions.Null_Id;
-
- -- Note: the caller will undefer abortion on return (see WARNING above)
-
- if not Task_Do_Or_Queue
- (Self_Id, Entry_Call, With_Abort => True)
- then
- Self_Id.ATC_Nesting_Level := Self_Id.ATC_Nesting_Level - 1;
- Initialization.Undefer_Abort (Self_Id);
- pragma Debug
- (Debug.Trace (Self_Id, "CS: exited to ATC level: " &
- ATC_Level'Image (Self_Id.ATC_Nesting_Level), 'A'));
- raise Tasking_Error;
- end if;
-
- STPO.Write_Lock (Self_Id);
- pragma Debug
- (Debug.Trace (Self_Id, "Call_Synchronous: wait", 'R'));
- Entry_Calls.Wait_For_Completion (Self_Id, Entry_Call);
- pragma Debug
- (Debug.Trace (Self_Id, "Call_Synchronous: done waiting", 'R'));
- Rendezvous_Successful := Entry_Call.State = Done;
- STPO.Unlock (Self_Id);
- Local_Undefer_Abort (Self_Id);
- Entry_Calls.Check_Exception (Self_Id, Entry_Call);
- end Call_Synchronous;
-
- --------------
- -- Callable --
- --------------
-
- -- Compiler interface.
- -- Do not call from within the RTS,
- -- except for body of Ada.Task_Identification.
-
- function Callable (T : Task_ID) return Boolean is
- Result : Boolean;
- Self_Id : constant Task_ID := STPO.Self;
-
- begin
- Initialization.Defer_Abort (Self_Id);
- STPO.Write_Lock (T);
- Result := T.Callable;
- STPO.Unlock (T);
- Initialization.Undefer_Abort (Self_Id);
- return Result;
- end Callable;
-
- ----------------------------
- -- Cancel_Task_Entry_Call --
- ----------------------------
-
- -- Compiler interface only. Do not call from within the RTS.
- -- Call only with abort deferred.
-
- procedure Cancel_Task_Entry_Call (Cancelled : out Boolean) is
- begin
- Entry_Calls.Try_To_Cancel_Entry_Call (Cancelled);
- end Cancel_Task_Entry_Call;
-
- -------------------------
- -- Complete_Rendezvous --
- -------------------------
-
- -- See comments for Exceptional_Complete_Rendezvous.
-
- procedure Complete_Rendezvous is
- begin
- Exceptional_Complete_Rendezvous (Ada.Exceptions.Null_Id);
- end Complete_Rendezvous;
-
- -------------------------------------
- -- Exceptional_Complete_Rendezvous --
- -------------------------------------
-
- -- Compiler interface.
- -- Also called from Complete_Rendezvous.
- -- ?????
- -- Consider phasing out Complete_Rendezvous in favor
- -- of direct call to this with Ada.Exceptions.Null_ID.
- -- See code expansion examples for Accept_Call and Selective_Wait.
- -- ?????
- -- If we don't change the interface, consider instead
- -- putting an explicit re-raise after this call, in
- -- the generated code. That way we could eliminate the
- -- code here that reraises the exception.
-
- -- The deferral level is critical here,
- -- since we want to raise an exception or allow abort to take
- -- place, if there is an exception or abort pending.
-
- procedure Exceptional_Complete_Rendezvous
- (Ex : Ada.Exceptions.Exception_Id)
- is
- Self_Id : constant Task_ID := STPO.Self;
- Entry_Call : Entry_Call_Link := Self_Id.Common.Call;
- Caller : Task_ID;
- Called_PO : STPE.Protection_Entries_Access;
-
- Exception_To_Raise : Ada.Exceptions.Exception_Id := Ex;
- Ceiling_Violation : Boolean;
-
- use type Ada.Exceptions.Exception_Id;
- procedure Internal_Reraise;
- pragma Import (C, Internal_Reraise, "__gnat_reraise");
-
- use type STPE.Protection_Entries_Access;
-
- begin
- pragma Debug
- (Debug.Trace (Self_Id, "Exceptional_Complete_Rendezvous", 'R'));
-
- if Ex = Ada.Exceptions.Null_Id then
- -- The call came from normal end-of-rendezvous,
- -- so abort is not yet deferred.
- Initialization.Defer_Abort_Nestable (Self_Id);
- end if;
-
- -- We need to clean up any accepts which Self may have
- -- been serving when it was aborted.
-
- if Ex = Standard'Abort_Signal'Identity then
- while Entry_Call /= null loop
- Entry_Call.Exception_To_Raise := Tasking_Error'Identity;
-
- -- All forms of accept make sure that the acceptor is not
- -- completed, before accepting further calls, so that we
- -- can be sure that no further calls are made after the
- -- current calls are purged.
-
- Caller := Entry_Call.Self;
-
- -- Take write lock. This follows the lock precedence rule that
- -- Caller may be locked while holding lock of Acceptor.
- -- Complete the call abnormally, with exception.
-
- STPO.Write_Lock (Caller);
-
- Initialization.Wakeup_Entry_Caller (Self_Id, Entry_Call, Done);
- STPO.Unlock (Caller);
- Entry_Call := Entry_Call.Acceptor_Prev_Call;
- end loop;
-
- else
- Caller := Entry_Call.Self;
-
- if Entry_Call.Needs_Requeue then
- -- We dare not lock Self_Id at the same time as Caller,
- -- for fear of deadlock.
-
- Entry_Call.Needs_Requeue := False;
- Self_Id.Common.Call := Entry_Call.Acceptor_Prev_Call;
-
- if Entry_Call.Called_Task /= null then
- -- Requeue to another task entry
-
- if not Task_Do_Or_Queue
- (Self_Id, Entry_Call, Entry_Call.Requeue_With_Abort)
- then
- Initialization.Undefer_Abort (Self_Id);
- raise Tasking_Error;
- end if;
-
- else
- -- Requeue to a protected entry
-
- Called_PO := POE.To_Protection (Entry_Call.Called_PO);
- STPE.Lock_Entries (Called_PO, Ceiling_Violation);
-
- if Ceiling_Violation then
- pragma Assert (Ex = Ada.Exceptions.Null_Id);
-
- Exception_To_Raise := Program_Error'Identity;
- Entry_Call.Exception_To_Raise := Exception_To_Raise;
- STPO.Write_Lock (Caller);
- Initialization.Wakeup_Entry_Caller
- (Self_Id, Entry_Call, Done);
- STPO.Unlock (Caller);
-
- else
- POO.PO_Do_Or_Queue
- (Self_Id, Called_PO, Entry_Call,
- Entry_Call.Requeue_With_Abort);
- POO.PO_Service_Entries (Self_Id, Called_PO);
- STPE.Unlock_Entries (Called_PO);
- end if;
- end if;
-
- Entry_Calls.Reset_Priority (Entry_Call.Acceptor_Prev_Priority,
- Self_Id);
-
- else
- -- The call does not need to be requeued.
-
- Self_Id.Common.Call := Entry_Call.Acceptor_Prev_Call;
- Entry_Call.Exception_To_Raise := Ex;
- STPO.Write_Lock (Caller);
-
- -- Done with Caller locked to make sure that Wakeup is not lost.
-
- if Ex /= Ada.Exceptions.Null_Id then
- Ada.Exceptions.Save_Occurrence
- (Caller.Common.Compiler_Data.Current_Excep,
- Self_Id.Common.Compiler_Data.Current_Excep);
- end if;
-
- Initialization.Wakeup_Entry_Caller (Self_Id, Entry_Call, Done);
- STPO.Unlock (Caller);
- Entry_Calls.Reset_Priority (Entry_Call.Acceptor_Prev_Priority,
- Self_Id);
- end if;
- end if;
-
- Initialization.Undefer_Abort (Self_Id);
-
- if Exception_To_Raise /= Ada.Exceptions.Null_Id then
- Internal_Reraise;
- end if;
-
- -- ?????
- -- Do we need to
- -- give precedence to Program_Error that might be raised
- -- due to failure of finalization, over Tasking_Error from
- -- failure of requeue?
- end Exceptional_Complete_Rendezvous;
-
- -------------------
- -- Is_Entry_Open --
- -------------------
-
- -- Call this only with abort deferred and holding lock of T.
-
- function Is_Entry_Open (T : Task_ID; E : Task_Entry_Index) return Boolean is
- begin
- pragma Assert (T.Open_Accepts /= null);
-
- if T.Open_Accepts /= null then
- for J in T.Open_Accepts'Range loop
-
- pragma Assert (J > 0);
-
- if E = T.Open_Accepts (J).S then
- return True;
- end if;
- end loop;
- end if;
-
- return False;
- end Is_Entry_Open;
-
- -------------------------------------
- -- Requeue_Protected_To_Task_Entry --
- -------------------------------------
-
- -- Compiler interface only. Do not call from within the RTS.
-
- -- entry e2 when b is
- -- begin
- -- b := false;
- -- ...A...
- -- requeue t.e2;
- -- end e2;
-
- -- procedure rPT__E14b (O : address; P : address; E :
- -- protected_entry_index) is
- -- type rTVP is access rTV;
- -- freeze rTVP []
- -- _object : rTVP := rTVP!(O);
- -- begin
- -- declare
- -- rR : protection renames _object._object;
- -- vP : integer renames _object.v;
- -- bP : boolean renames _object.b;
- -- begin
- -- b := false;
- -- ...A...
- -- requeue_protected_to_task_entry (rR'unchecked_access, tTV!(t).
- -- _task_id, 2, false);
- -- return;
- -- end;
- -- complete_entry_body (_object._object'unchecked_access, objectF =>
- -- 0);
- -- return;
- -- exception
- -- when others =>
- -- abort_undefer.all;
- -- exceptional_complete_entry_body (_object._object'
- -- unchecked_access, current_exception, objectF => 0);
- -- return;
- -- end rPT__E14b;
-
- procedure Requeue_Protected_To_Task_Entry
- (Object : STPE.Protection_Entries_Access;
- Acceptor : Task_ID;
- E : Task_Entry_Index;
- With_Abort : Boolean)
- is
- Entry_Call : constant Entry_Call_Link := Object.Call_In_Progress;
- begin
- pragma Assert (STPO.Self.Deferral_Level > 0);
-
- Entry_Call.E := Entry_Index (E);
- Entry_Call.Called_Task := Acceptor;
- Entry_Call.Called_PO := Null_Address;
- Entry_Call.Requeue_With_Abort := With_Abort;
- Object.Call_In_Progress := null;
- end Requeue_Protected_To_Task_Entry;
-
- ------------------------
- -- Requeue_Task_Entry --
- ------------------------
-
- -- Compiler interface only. Do not call from within the RTS.
- -- The code generation for task entry requeues is different from that
- -- for protected entry requeues. There is a "goto" that skips around
- -- the call to Complete_Rendezous, so that Requeue_Task_Entry must also
- -- do the work of Complete_Rendezvous. The difference is that it does
- -- not report that the call's State = Done.
-
- -- accept e1 do
- -- ...A...
- -- requeue e2;
- -- ...B...
- -- end e1;
-
- -- A62b : address;
- -- L61b : label
- -- begin
- -- accept_call (1, A62b);
- -- ...A...
- -- requeue_task_entry (tTV!(t)._task_id, 2, false);
- -- goto L61b;
- -- ...B...
- -- complete_rendezvous;
- -- <<L61b>>
- -- exception
- -- when others =>
- -- exceptional_complete_rendezvous (current_exception);
- -- end;
-
- procedure Requeue_Task_Entry
- (Acceptor : Task_ID;
- E : Task_Entry_Index;
- With_Abort : Boolean)
- is
- Self_Id : constant Task_ID := STPO.Self;
- Entry_Call : constant Entry_Call_Link := Self_Id.Common.Call;
-
- begin
- Initialization.Defer_Abort (Self_Id);
- Entry_Call.Needs_Requeue := True;
- Entry_Call.Requeue_With_Abort := With_Abort;
- Entry_Call.E := Entry_Index (E);
- Entry_Call.Called_Task := Acceptor;
- Initialization.Undefer_Abort (Self_Id);
- end Requeue_Task_Entry;
-
- --------------------
- -- Selective_Wait --
- --------------------
-
- -- Compiler interface only. Do not call from within the RTS.
- -- See comments on Accept_Call.
-
- -- source code:
-
- -- select accept e1 do
- -- ...A...
- -- end e1;
- -- ...B...
- -- or accept e2;
- -- ...C...
- -- end select;
-
- -- expansion:
-
- -- A32b : address;
- -- declare
- -- null;
- -- if accept_alternative'size * 2 >= 16#8000_0000# then
- -- raise storage_error;
- -- end if;
- -- A37b : T36b;
- -- A37b (1) := (null_body => false, s => 1);
- -- A37b (2) := (null_body => true, s => 2);
- -- if accept_alternative'size * 2 >= 16#8000_0000# then
- -- raise storage_error;
- -- end if;
- -- S0 : aliased T36b := accept_list'A37b;
- -- J1 : select_index := 0;
- -- L3 : label
- -- L1 : label
- -- L2 : label
- -- procedure e1A is
- -- begin
- -- abort_undefer.all;
- -- L31b : label
- -- ...A...
- -- <<L31b>>
- -- complete_rendezvous;
- -- exception
- -- when all others =>
- -- exceptional_complete_rendezvous (get_gnat_exception);
- -- end e1A;
- -- begin
- -- selective_wait (S0'unchecked_access, simple_mode, A32b, J1);
- -- case J1 is
- -- when 0 =>
- -- goto L3;
- -- when 1 =>
- -- e1A;
- -- goto L1;
- -- when 2 =>
- -- goto L2;
- -- when others =>
- -- goto L3;
- -- end case;
- -- <<L1>>
- -- ...B...
- -- goto L3;
- -- <<L2>>
- -- ...C...
- -- goto L3;
- -- <<L3>>
- -- end;
-
- procedure Selective_Wait
- (Open_Accepts : Accept_List_Access;
- Select_Mode : Select_Modes;
- Uninterpreted_Data : out System.Address;
- Index : out Select_Index)
- is
- Self_Id : constant Task_ID := STPO.Self;
- Entry_Call : Entry_Call_Link;
- Treatment : Select_Treatment;
- Caller : Task_ID;
- Selection : Select_Index;
- Open_Alternative : Boolean;
-
- begin
- Initialization.Defer_Abort (Self_Id);
- STPO.Write_Lock (Self_Id);
-
- if not Self_Id.Callable then
- pragma Assert (Self_Id.Pending_ATC_Level = 0);
-
- pragma Assert (Self_Id.Pending_Action);
-
- STPO.Unlock (Self_Id);
-
- -- ??? In some cases abort is deferred more than once. Need to figure
- -- out why.
-
- Self_Id.Deferral_Level := 1;
-
- Initialization.Undefer_Abort (Self_Id);
-
- -- Should never get here ???
-
- pragma Assert (False);
- raise Standard'Abort_Signal;
- end if;
-
- -- If someone completed this task, this task should not try to
- -- access its pending entry calls or queues in this case, as they
- -- are being emptied. Wait for abortion to kill us.
- -- ?????
- -- Recheck the correctness of the above, now that we have made
- -- changes.
-
- pragma Assert (Open_Accepts /= null);
-
- Queuing.Select_Task_Entry_Call
- (Self_Id, Open_Accepts, Entry_Call, Selection, Open_Alternative);
-
- -- Determine the kind and disposition of the select.
-
- Treatment := Default_Treatment (Select_Mode);
- Self_Id.Chosen_Index := No_Rendezvous;
-
- if Open_Alternative then
- if Entry_Call /= null then
- if Open_Accepts (Selection).Null_Body then
- Treatment := Accept_Alternative_Completed;
-
- else
- Setup_For_Rendezvous_With_Body (Entry_Call, Self_Id);
- Treatment := Accept_Alternative_Selected;
- end if;
-
- Self_Id.Chosen_Index := Selection;
-
- elsif Treatment = No_Alternative_Open then
- Treatment := Accept_Alternative_Open;
- end if;
- end if;
-
- -- ??????
- -- Recheck the logic above against the ARM.
-
- -- Handle the select according to the disposition selected above.
-
- case Treatment is
-
- when Accept_Alternative_Selected =>
-
- -- Ready to rendezvous
-
- Uninterpreted_Data := Self_Id.Common.Call.Uninterpreted_Data;
-
- -- In this case the accept body is not Null_Body. Defer abortion
- -- until it gets into the accept body.
-
- pragma Assert (Self_Id.Deferral_Level = 1);
-
- Initialization.Defer_Abort_Nestable (Self_Id);
- STPO.Unlock (Self_Id);
-
- when Accept_Alternative_Completed =>
-
- -- Accept body is null, so rendezvous is over immediately.
-
- STPO.Unlock (Self_Id);
- Caller := Entry_Call.Self;
-
- STPO.Write_Lock (Caller);
- Initialization.Wakeup_Entry_Caller (Self_Id, Entry_Call, Done);
- STPO.Unlock (Caller);
-
- when Accept_Alternative_Open =>
-
- -- Wait for caller.
-
- Self_Id.Open_Accepts := Open_Accepts;
- pragma Debug
- (Debug.Trace (Self_Id, "Selective_Wait: wait", 'R'));
- Wait_For_Call (Self_Id);
-
- pragma Assert (Self_Id.Open_Accepts = null);
-
- -- Self_Id.Common.Call should already be updated by the Caller if
- -- not aborted. It might also be ready to do rendezvous even if
- -- this wakes up due to an abortion.
- -- Therefore, if the call is not empty we need to do the rendezvous
- -- if the accept body is not Null_Body.
-
- -- ?????
- -- aren't the first two conditions below redundant?
-
- if Self_Id.Chosen_Index /= No_Rendezvous and then
- Self_Id.Common.Call /= null and then
- not Open_Accepts (Self_Id.Chosen_Index).Null_Body
- then
- Uninterpreted_Data := Self_Id.Common.Call.Uninterpreted_Data;
-
- pragma Assert (Self_Id.Deferral_Level = 1);
-
- Initialization.Defer_Abort_Nestable (Self_Id);
-
- -- Leave abort deferred until the accept body
- end if;
-
- STPO.Unlock (Self_Id);
-
- when Else_Selected =>
- pragma Assert (Self_Id.Open_Accepts = null);
-
- STPO.Unlock (Self_Id);
-
- when Terminate_Selected =>
-
- -- Terminate alternative is open
-
- Self_Id.Open_Accepts := Open_Accepts;
- Self_Id.Common.State := Acceptor_Sleep;
- STPO.Unlock (Self_Id);
-
- -- ?????
- -- We need to check if a signal is pending on an open interrupt
- -- entry. Otherwise this task would become potentially terminatable
- -- and, if none of the siblings are active
- -- any more, the task could not wake up any more, even though a
- -- signal might be pending on an open interrupt entry.
- -- -------------
- -- This comment paragraph does not make sense. Is it obsolete?
- -- There was no code here to check for pending signals.
-
- -- Notify ancestors that this task is on a terminate alternative.
-
- Utilities.Make_Passive (Self_Id, Task_Completed => False);
-
- -- Wait for normal entry call or termination
-
- pragma Assert (Self_Id.ATC_Nesting_Level = 1);
-
- STPO.Write_Lock (Self_Id);
-
- loop
- Initialization.Poll_Base_Priority_Change (Self_Id);
- exit when Self_Id.Open_Accepts = null;
- Sleep (Self_Id, Acceptor_Sleep);
- end loop;
-
- Self_Id.Common.State := Runnable;
-
- pragma Assert (Self_Id.Open_Accepts = null);
-
- if Self_Id.Terminate_Alternative then
-
- -- An entry call should have reset this to False,
- -- so we must be aborted.
- -- We cannot be in an async. select, since that
- -- is not legal, so the abort must be of the entire
- -- task. Therefore, we do not need to cancel the
- -- terminate alternative. The cleanup will be done
- -- in Complete_Master.
-
- pragma Assert (Self_Id.Pending_ATC_Level = 0);
-
- pragma Assert (Self_Id.Awake_Count = 0);
-
- -- Trust that it is OK to fall through.
-
- null;
-
- else
- -- Self_Id.Common.Call and Self_Id.Chosen_Index
- -- should already be updated by the Caller.
-
- if Self_Id.Chosen_Index /= No_Rendezvous
- and then not Open_Accepts (Self_Id.Chosen_Index).Null_Body
- then
- Uninterpreted_Data := Self_Id.Common.Call.Uninterpreted_Data;
-
- pragma Assert (Self_Id.Deferral_Level = 1);
-
- -- We need an extra defer here, to keep abort
- -- deferred until we get into the accept body
-
- Initialization.Defer_Abort_Nestable (Self_Id);
- end if;
- end if;
-
- STPO.Unlock (Self_Id);
-
- when No_Alternative_Open =>
-
- -- In this case, Index will be No_Rendezvous on return, which
- -- should cause a Program_Error if it is not a Delay_Mode.
-
- -- If delay alternative exists (Delay_Mode) we should suspend
- -- until the delay expires.
-
- Self_Id.Open_Accepts := null;
-
- if Select_Mode = Delay_Mode then
- Self_Id.Common.State := Delay_Sleep;
-
- loop
- Initialization.Poll_Base_Priority_Change (Self_Id);
- exit when Self_Id.Pending_ATC_Level < Self_Id.ATC_Nesting_Level;
- Sleep (Self_Id, Delay_Sleep);
- end loop;
-
- Self_Id.Common.State := Runnable;
- STPO.Unlock (Self_Id);
-
- else
- STPO.Unlock (Self_Id);
- Initialization.Undefer_Abort (Self_Id);
- Ada.Exceptions.Raise_Exception (Program_Error'Identity,
- "Entry call not a delay mode");
- end if;
-
- end case;
-
- -- Caller has been chosen.
- -- Self_Id.Common.Call should already be updated by the Caller.
- -- Self_Id.Chosen_Index should either be updated by the Caller
- -- or by Test_Selective_Wait.
- -- On return, we sill start rendezvous unless the accept body is
- -- null. In the latter case, we will have already completed the RV.
-
- Index := Self_Id.Chosen_Index;
- Initialization.Undefer_Abort_Nestable (Self_Id);
-
- end Selective_Wait;
-
- ------------------------------------
- -- Setup_For_Rendezvous_With_Body --
- ------------------------------------
-
- -- Call this only with abort deferred and holding lock of Acceptor.
-
- procedure Setup_For_Rendezvous_With_Body
- (Entry_Call : Entry_Call_Link;
- Acceptor : Task_ID)
- is
- begin
- Entry_Call.Acceptor_Prev_Call := Acceptor.Common.Call;
- Acceptor.Common.Call := Entry_Call;
-
- if Entry_Call.State = Now_Abortable then
- Entry_Call.State := Was_Abortable;
- end if;
-
- Boost_Priority (Entry_Call, Acceptor);
- end Setup_For_Rendezvous_With_Body;
-
- ----------------
- -- Task_Count --
- ----------------
-
- -- Compiler interface only. Do not call from within the RTS.
-
- function Task_Count (E : Task_Entry_Index) return Natural is
- Self_Id : constant Task_ID := STPO.Self;
- Return_Count : Natural;
-
- begin
- Initialization.Defer_Abort (Self_Id);
- STPO.Write_Lock (Self_Id);
- Return_Count := Queuing.Count_Waiting (Self_Id.Entry_Queues (E));
- STPO.Unlock (Self_Id);
- Initialization.Undefer_Abort (Self_Id);
- return Return_Count;
- end Task_Count;
-
- ----------------------
- -- Task_Do_Or_Queue --
- ----------------------
-
- -- Call this only with abort deferred and holding no locks.
- -- May propagate an exception, including Abort_Signal & Tasking_Error.
- -- ?????
- -- See Check_Callable. Check all call contexts to verify
- -- it is OK to raise an exception.
-
- -- Find out whether Entry_Call can be accepted immediately.
- -- If the Acceptor is not callable, raise Tasking_Error.
- -- If the rendezvous can start, initiate it.
- -- If the accept-body is trivial, also complete the rendezvous.
- -- If the acceptor is not ready, enqueue the call.
-
- -- ?????
- -- This should have a special case for Accept_Call and
- -- Accept_Trivial, so that
- -- we don't have the loop setup overhead, below.
-
- -- ?????
- -- The call state Done is used here and elsewhere to include
- -- both the case of normal successful completion, and the case
- -- of an exception being raised. The difference is that if an
- -- exception is raised no one will pay attention to the fact
- -- that State = Done. Instead the exception will be raised in
- -- Undefer_Abort, and control will skip past the place where
- -- we normally would resume from an entry call.
-
- function Task_Do_Or_Queue
- (Self_ID : Task_ID;
- Entry_Call : Entry_Call_Link;
- With_Abort : Boolean) return Boolean
- is
- E : constant Task_Entry_Index := Task_Entry_Index (Entry_Call.E);
- Old_State : constant Entry_Call_State := Entry_Call.State;
- Acceptor : constant Task_ID := Entry_Call.Called_Task;
- Parent : constant Task_ID := Acceptor.Common.Parent;
- Parent_Locked : Boolean := False;
- Null_Body : Boolean;
-
- begin
- pragma Assert (not Queuing.Onqueue (Entry_Call));
-
- -- We rely that the call is off-queue for protection,
- -- that the caller will not exit the Entry_Caller_Sleep,
- -- and so will not reuse the call record for another call.
- -- We rely on the Caller's lock for call State mod's.
-
- -- We can't lock Acceptor.Parent while holding Acceptor,
- -- so lock it in advance if we expect to need to lock it.
- -- ?????
- -- Is there some better solution?
-
- if Acceptor.Terminate_Alternative then
- STPO.Write_Lock (Parent);
- Parent_Locked := True;
- end if;
-
- STPO.Write_Lock (Acceptor);
-
- -- If the acceptor is not callable, abort the call
- -- and raise Tasking_Error. The call is not aborted
- -- for an asynchronous call, since Cancel_Task_Entry_Call
- -- will do the cancelation in that case.
- -- ????? .....
- -- Does the above still make sense?
-
- if not Acceptor.Callable then
- STPO.Unlock (Acceptor);
-
- if Parent_Locked then
- STPO.Unlock (Acceptor.Common.Parent);
- end if;
-
- pragma Assert (Entry_Call.State < Done);
-
- -- In case we are not the caller, set up the caller
- -- to raise Tasking_Error when it wakes up.
-
- STPO.Write_Lock (Entry_Call.Self);
- Entry_Call.Exception_To_Raise := Tasking_Error'Identity;
- Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Done);
- STPO.Unlock (Entry_Call.Self);
- return False;
- end if;
-
- -- Try to serve the call immediately.
-
- if Acceptor.Open_Accepts /= null then
- for J in Acceptor.Open_Accepts'Range loop
- if Entry_Call.E = Entry_Index (Acceptor.Open_Accepts (J).S) then
-
- -- Commit acceptor to rendezvous with us.
-
- Acceptor.Chosen_Index := J;
- Null_Body := Acceptor.Open_Accepts (J).Null_Body;
- Acceptor.Open_Accepts := null;
-
- -- Prevent abort while call is being served.
-
- if Entry_Call.State = Now_Abortable then
- Entry_Call.State := Was_Abortable;
- end if;
-
- if Acceptor.Terminate_Alternative then
-
- -- Cancel terminate alternative.
- -- See matching code in Selective_Wait and
- -- Vulnerable_Complete_Master.
-
- Acceptor.Terminate_Alternative := False;
- Acceptor.Awake_Count := Acceptor.Awake_Count + 1;
-
- if Acceptor.Awake_Count = 1 then
-
- -- Notify parent that acceptor is awake.
-
- pragma Assert (Parent.Awake_Count > 0);
-
- Parent.Awake_Count := Parent.Awake_Count + 1;
-
- if Parent.Common.State = Master_Completion_Sleep and then
- Acceptor.Master_of_Task = Parent.Master_Within
- then
- Parent.Common.Wait_Count :=
- Parent.Common.Wait_Count + 1;
- end if;
- end if;
- end if;
-
- if Null_Body then
-
- -- Rendezvous is over immediately.
-
- STPO.Wakeup (Acceptor, Acceptor_Sleep);
- STPO.Unlock (Acceptor);
-
- if Parent_Locked then
- STPO.Unlock (Parent);
- end if;
-
- STPO.Write_Lock (Entry_Call.Self);
- Initialization.Wakeup_Entry_Caller
- (Self_ID, Entry_Call, Done);
- STPO.Unlock (Entry_Call.Self);
-
- else
- Setup_For_Rendezvous_With_Body (Entry_Call, Acceptor);
-
- -- For terminate_alternative, acceptor may not be
- -- asleep yet, so we skip the wakeup
-
- if Acceptor.Common.State /= Runnable then
- STPO.Wakeup (Acceptor, Acceptor_Sleep);
- end if;
-
- STPO.Unlock (Acceptor);
-
- if Parent_Locked then
- STPO.Unlock (Parent);
- end if;
- end if;
-
- return True;
- end if;
- end loop;
-
- -- The acceptor is accepting, but not this entry.
- end if;
-
- -- If the acceptor was ready to accept this call,
- -- we would not have gotten this far, so now we should
- -- (re)enqueue the call, if the mode permits that.
-
- if Entry_Call.Mode /= Conditional_Call
- or else not With_Abort
- then
- -- Timed_Call, Simple_Call, or Asynchronous_Call
-
- Queuing.Enqueue (Acceptor.Entry_Queues (E), Entry_Call);
-
- -- Update abortability of call
-
- pragma Assert (Old_State < Done);
-
- Entry_Call.State := New_State (With_Abort, Entry_Call.State);
-
- STPO.Unlock (Acceptor);
-
- if Parent_Locked then
- STPO.Unlock (Parent);
- end if;
-
- if Old_State /= Entry_Call.State and then
- Entry_Call.State = Now_Abortable and then
- Entry_Call.Mode > Simple_Call and then
-
- -- Asynchronous_Call or Conditional_Call
-
- Entry_Call.Self /= Self_ID
-
- then
- -- Because of ATCB lock ordering rule
-
- STPO.Write_Lock (Entry_Call.Self);
-
- if Entry_Call.Self.Common.State = Async_Select_Sleep then
-
- -- Caller may not yet have reached wait-point
-
- STPO.Wakeup (Entry_Call.Self, Async_Select_Sleep);
- end if;
-
- STPO.Unlock (Entry_Call.Self);
- end if;
-
- else
- -- Conditional_Call and With_Abort
-
- STPO.Unlock (Acceptor);
-
- if Parent_Locked then
- STPO.Unlock (Parent);
- end if;
-
- STPO.Write_Lock (Entry_Call.Self);
-
- pragma Assert (Entry_Call.State >= Was_Abortable);
-
- Initialization.Wakeup_Entry_Caller (Self_ID, Entry_Call, Cancelled);
- STPO.Unlock (Entry_Call.Self);
- end if;
-
- return True;
- end Task_Do_Or_Queue;
-
- ---------------------
- -- Task_Entry_Call --
- ---------------------
-
- procedure Task_Entry_Call
- (Acceptor : Task_ID;
- E : Task_Entry_Index;
- Uninterpreted_Data : System.Address;
- Mode : Call_Modes;
- Rendezvous_Successful : out Boolean)
- is
- Self_Id : constant Task_ID := STPO.Self;
- Entry_Call : Entry_Call_Link;
-
- begin
- if Mode = Simple_Call or else Mode = Conditional_Call then
- Call_Synchronous
- (Acceptor, E, Uninterpreted_Data, Mode, Rendezvous_Successful);
-
- else
- -- This is an asynchronous call
-
- -- Abortion must already be deferred by the compiler-generated
- -- code. Without this, an abortion that occurs between the time
- -- that this call is made and the time that the abortable part's
- -- cleanup handler is set up might miss the cleanup handler and
- -- leave the call pending.
-
- Self_Id.ATC_Nesting_Level := Self_Id.ATC_Nesting_Level + 1;
- pragma Debug
- (Debug.Trace (Self_Id, "TEC: entered ATC level: " &
- ATC_Level'Image (Self_Id.ATC_Nesting_Level), 'A'));
- Entry_Call := Self_Id.Entry_Calls (Self_Id.ATC_Nesting_Level)'Access;
- Entry_Call.Next := null;
- Entry_Call.Mode := Mode;
- Entry_Call.Cancellation_Attempted := False;
- Entry_Call.State := Not_Yet_Abortable;
- Entry_Call.E := Entry_Index (E);
- Entry_Call.Prio := Get_Priority (Self_Id);
- Entry_Call.Uninterpreted_Data := Uninterpreted_Data;
- Entry_Call.Called_Task := Acceptor;
- Entry_Call.Called_PO := Null_Address;
- Entry_Call.Exception_To_Raise := Ada.Exceptions.Null_Id;
-
- if not Task_Do_Or_Queue
- (Self_Id, Entry_Call, With_Abort => True)
- then
- Self_Id.ATC_Nesting_Level := Self_Id.ATC_Nesting_Level - 1;
- pragma Debug
- (Debug.Trace (Self_Id, "TEC: exited to ATC level: " &
- ATC_Level'Image (Self_Id.ATC_Nesting_Level), 'A'));
- Initialization.Undefer_Abort (Self_Id);
- raise Tasking_Error;
- end if;
-
- -- The following is special for async. entry calls.
- -- If the call was not queued abortably, we need to wait until
- -- it is before proceeding with the abortable part.
-
- -- Wait_Until_Abortable can be called unconditionally here,
- -- but it is expensive.
-
- if Entry_Call.State < Was_Abortable then
- Entry_Calls.Wait_Until_Abortable (Self_Id, Entry_Call);
- end if;
-
- -- Note: following assignment needs to be atomic.
-
- Rendezvous_Successful := Entry_Call.State = Done;
- end if;
- end Task_Entry_Call;
-
- -----------------------
- -- Task_Entry_Caller --
- -----------------------
-
- -- Compiler interface only.
-
- function Task_Entry_Caller (D : Task_Entry_Nesting_Depth) return Task_ID is
- Self_Id : constant Task_ID := STPO.Self;
- Entry_Call : Entry_Call_Link;
-
- begin
- Entry_Call := Self_Id.Common.Call;
- for Depth in 1 .. D loop
- Entry_Call := Entry_Call.Acceptor_Prev_Call;
- pragma Assert (Entry_Call /= null);
- end loop;
-
- return Entry_Call.Self;
- end Task_Entry_Caller;
-
- --------------------------
- -- Timed_Selective_Wait --
- --------------------------
-
- -- Compiler interface only. Do not call from within the RTS.
-
- procedure Timed_Selective_Wait
- (Open_Accepts : Accept_List_Access;
- Select_Mode : Select_Modes;
- Uninterpreted_Data : out System.Address;
- Timeout : Duration;
- Mode : Delay_Modes;
- Index : out Select_Index)
- is
- Self_Id : constant Task_ID := STPO.Self;
- Treatment : Select_Treatment;
- Entry_Call : Entry_Call_Link;
- Caller : Task_ID;
- Selection : Select_Index;
- Open_Alternative : Boolean;
- Timedout : Boolean := False;
- Yielded : Boolean := False;
- begin
- pragma Assert (Select_Mode = Delay_Mode);
-
- Initialization.Defer_Abort (Self_Id);
-
- -- If we are aborted here, the effect will be pending
-
- STPO.Write_Lock (Self_Id);
-
- if not Self_Id.Callable then
- pragma Assert (Self_Id.Pending_ATC_Level = 0);
-
- pragma Assert (Self_Id.Pending_Action);
-
- STPO.Unlock (Self_Id);
- Initialization.Undefer_Abort (Self_Id);
-
- -- Should never get here ???
-
- pragma Assert (False);
- raise Standard'Abort_Signal;
- end if;
-
- -- If someone completed this task, this task should not try to
- -- access its pending entry calls or queues in this case, as they
- -- are being emptied. Wait for abortion to kill us.
- -- ?????
- -- Recheck the correctness of the above, now that we have made
- -- changes.
-
- pragma Assert (Open_Accepts /= null);
-
- Queuing.Select_Task_Entry_Call
- (Self_Id, Open_Accepts, Entry_Call, Selection, Open_Alternative);
-
- -- Determine the kind and disposition of the select.
-
- Treatment := Default_Treatment (Select_Mode);
- Self_Id.Chosen_Index := No_Rendezvous;
-
- if Open_Alternative then
- if Entry_Call /= null then
- if Open_Accepts (Selection).Null_Body then
- Treatment := Accept_Alternative_Completed;
-
- else
- Setup_For_Rendezvous_With_Body (Entry_Call, Self_Id);
- Treatment := Accept_Alternative_Selected;
- end if;
-
- Self_Id.Chosen_Index := Selection;
-
- elsif Treatment = No_Alternative_Open then
- Treatment := Accept_Alternative_Open;
- end if;
- end if;
-
- -- Handle the select according to the disposition selected above.
-
- case Treatment is
-
- when Accept_Alternative_Selected =>
-
- -- Ready to rendezvous
- -- In this case the accept body is not Null_Body. Defer abortion
- -- until it gets into the accept body.
-
- Uninterpreted_Data := Self_Id.Common.Call.Uninterpreted_Data;
- Initialization.Defer_Abort (Self_Id);
- STPO.Unlock (Self_Id);
-
- when Accept_Alternative_Completed =>
-
- -- Rendezvous is over
-
- STPO.Unlock (Self_Id);
- Caller := Entry_Call.Self;
-
- STPO.Write_Lock (Caller);
- Initialization.Wakeup_Entry_Caller (Self_Id, Entry_Call, Done);
- STPO.Unlock (Caller);
-
- when Accept_Alternative_Open =>
-
- -- Wait for caller.
-
- Self_Id.Open_Accepts := Open_Accepts;
-
- -- Wait for a normal call and a pending action until the
- -- Wakeup_Time is reached.
-
- Self_Id.Common.State := Acceptor_Sleep;
-
- loop
- Initialization.Poll_Base_Priority_Change (Self_Id);
- exit when Self_Id.Open_Accepts = null;
-
- if Timedout then
- Sleep (Self_Id, Acceptor_Sleep);
- else
- STPO.Timed_Sleep (Self_Id, Timeout, Mode,
- Acceptor_Sleep, Timedout, Yielded);
- end if;
-
- if Timedout then
- Self_Id.Open_Accepts := null;
- end if;
- end loop;
-
- Self_Id.Common.State := Runnable;
-
- -- Self_Id.Common.Call should already be updated by the Caller if
- -- not aborted. It might also be ready to do rendezvous even if
- -- this wakes up due to an abortion.
- -- Therefore, if the call is not empty we need to do the rendezvous
- -- if the accept body is not Null_Body.
-
- if Self_Id.Chosen_Index /= No_Rendezvous and then
- Self_Id.Common.Call /= null and then
- not Open_Accepts (Self_Id.Chosen_Index).Null_Body
- then
- Uninterpreted_Data := Self_Id.Common.Call.Uninterpreted_Data;
-
- pragma Assert (Self_Id.Deferral_Level = 1);
-
- Initialization.Defer_Abort_Nestable (Self_Id);
-
- -- Leave abort deferred until the accept body
-
- end if;
-
- STPO.Unlock (Self_Id);
- if not Yielded then
- Yield;
- end if;
-
- when No_Alternative_Open =>
-
- -- In this case, Index will be No_Rendezvous on return. We sleep
- -- for the time we need to.
- -- Wait for a signal or timeout. A wakeup can be made
- -- for several reasons:
- -- 1) Delay is expired
- -- 2) Pending_Action needs to be checked
- -- (Abortion, Priority change)
- -- 3) Spurious wakeup
-
- Self_Id.Open_Accepts := null;
- Self_Id.Common.State := Acceptor_Sleep;
-
- Initialization.Poll_Base_Priority_Change (Self_Id);
-
- STPO.Timed_Sleep (Self_Id, Timeout, Mode, Acceptor_Sleep,
- Timedout, Yielded);
-
- Self_Id.Common.State := Runnable;
-
- STPO.Unlock (Self_Id);
-
- if not Yielded then
- Yield;
- end if;
-
- when others =>
- -- Should never get here ???
-
- pragma Assert (False);
- null;
- end case;
-
- -- Caller has been chosen
-
- -- Self_Id.Common.Call should already be updated by the Caller
-
- -- Self_Id.Chosen_Index should either be updated by the Caller
- -- or by Test_Selective_Wait
-
- Index := Self_Id.Chosen_Index;
- Initialization.Undefer_Abort_Nestable (Self_Id);
-
- -- Start rendezvous, if not already completed
-
- end Timed_Selective_Wait;
-
- ---------------------------
- -- Timed_Task_Entry_Call --
- ---------------------------
-
- -- Compiler interface only. Do not call from within the RTS.
-
- procedure Timed_Task_Entry_Call
- (Acceptor : Task_ID;
- E : Task_Entry_Index;
- Uninterpreted_Data : System.Address;
- Timeout : Duration;
- Mode : Delay_Modes;
- Rendezvous_Successful : out Boolean)
- is
- Self_Id : constant Task_ID := STPO.Self;
- Level : ATC_Level;
- Entry_Call : Entry_Call_Link;
-
- begin
- Initialization.Defer_Abort (Self_Id);
- Self_Id.ATC_Nesting_Level := Self_Id.ATC_Nesting_Level + 1;
-
- pragma Debug
- (Debug.Trace (Self_Id, "TTEC: entered ATC level: " &
- ATC_Level'Image (Self_Id.ATC_Nesting_Level), 'A'));
-
- Level := Self_Id.ATC_Nesting_Level;
- Entry_Call := Self_Id.Entry_Calls (Level)'Access;
- Entry_Call.Next := null;
- Entry_Call.Mode := Timed_Call;
- Entry_Call.Cancellation_Attempted := False;
-
- -- If this is a call made inside of an abort deferred region,
- -- the call should be never abortable.
-
- if Self_Id.Deferral_Level > 1 then
- Entry_Call.State := Never_Abortable;
- else
- Entry_Call.State := Now_Abortable;
- end if;
-
- Entry_Call.E := Entry_Index (E);
- Entry_Call.Prio := Get_Priority (Self_Id);
- Entry_Call.Uninterpreted_Data := Uninterpreted_Data;
- Entry_Call.Called_Task := Acceptor;
- Entry_Call.Called_PO := Null_Address;
- Entry_Call.Exception_To_Raise := Ada.Exceptions.Null_Id;
-
- -- Note: the caller will undefer abortion on return (see WARNING above)
-
- if not Task_Do_Or_Queue
- (Self_Id, Entry_Call, With_Abort => True)
- then
- Self_Id.ATC_Nesting_Level := Self_Id.ATC_Nesting_Level - 1;
-
- pragma Debug
- (Debug.Trace (Self_Id, "TTEC: exited to ATC level: " &
- ATC_Level'Image (Self_Id.ATC_Nesting_Level), 'A'));
-
- Initialization.Undefer_Abort (Self_Id);
- raise Tasking_Error;
- end if;
-
- Entry_Calls.Wait_For_Completion_With_Timeout
- (Self_Id, Entry_Call, Timeout, Mode);
- Rendezvous_Successful := Entry_Call.State = Done;
- Initialization.Undefer_Abort (Self_Id);
- Entry_Calls.Check_Exception (Self_Id, Entry_Call);
- end Timed_Task_Entry_Call;
-
- -------------------
- -- Wait_For_Call --
- -------------------
-
- -- Call this only with abort deferred and holding lock of Self_Id.
- -- Wait for normal call and a pending action.
-
- procedure Wait_For_Call (Self_Id : Task_ID) is
- begin
- Self_Id.Common.State := Acceptor_Sleep;
-
- loop
- Initialization.Poll_Base_Priority_Change (Self_Id);
-
- exit when Self_Id.Open_Accepts = null;
-
- Sleep (Self_Id, Acceptor_Sleep);
- end loop;
-
- Self_Id.Common.State := Runnable;
- end Wait_For_Call;
-
-end System.Tasking.Rendezvous;
projects / msp430-gcc.git / blobdiff