aboutsummaryrefslogtreecommitdiffstats
path: root/gcc-4.8.3/gcc/ada/a-dynpri.adb
diff options
context:
space:
mode:
Diffstat (limited to 'gcc-4.8.3/gcc/ada/a-dynpri.adb')
-rw-r--r--gcc-4.8.3/gcc/ada/a-dynpri.adb164
1 files changed, 164 insertions, 0 deletions
diff --git a/gcc-4.8.3/gcc/ada/a-dynpri.adb b/gcc-4.8.3/gcc/ada/a-dynpri.adb
new file mode 100644
index 000000000..4e67934b7
--- /dev/null
+++ b/gcc-4.8.3/gcc/ada/a-dynpri.adb
@@ -0,0 +1,164 @@
+------------------------------------------------------------------------------
+-- --
+-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
+-- --
+-- A D A . D Y N A M I C _ P R I O R I T I E S --
+-- --
+-- B o d y --
+-- --
+-- Copyright (C) 1992-2012, Free Software Foundation, Inc. --
+-- --
+-- GNARL is free software; you can redistribute it and/or modify it under --
+-- terms of the GNU General Public License as published by the Free Soft- --
+-- ware Foundation; either version 3, or (at your option) any later ver- --
+-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
+-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
+-- --
+-- As a special exception under Section 7 of GPL version 3, you are granted --
+-- additional permissions described in the GCC Runtime Library Exception, --
+-- version 3.1, as published by the Free Software Foundation. --
+-- --
+-- You should have received a copy of the GNU General Public License and --
+-- a copy of the GCC Runtime Library Exception along with this program; --
+-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
+-- <http://www.gnu.org/licenses/>. --
+-- --
+-- GNARL was developed by the GNARL team at Florida State University. --
+-- Extensive contributions were provided by Ada Core Technologies, Inc. --
+-- --
+------------------------------------------------------------------------------
+
+with System.Task_Primitives.Operations;
+with System.Tasking;
+with System.Parameters;
+with System.Soft_Links;
+
+with Ada.Unchecked_Conversion;
+
+package body Ada.Dynamic_Priorities is
+
+ package STPO renames System.Task_Primitives.Operations;
+ package SSL renames System.Soft_Links;
+
+ use System.Parameters;
+ use System.Tasking;
+
+ function Convert_Ids is new
+ Ada.Unchecked_Conversion
+ (Task_Identification.Task_Id, System.Tasking.Task_Id);
+
+ ------------------
+ -- Get_Priority --
+ ------------------
+
+ -- Inquire base priority of a task
+
+ function Get_Priority
+ (T : Ada.Task_Identification.Task_Id :=
+ Ada.Task_Identification.Current_Task) return System.Any_Priority
+ is
+ Target : constant Task_Id := Convert_Ids (T);
+ Error_Message : constant String := "Trying to get the priority of a ";
+
+ begin
+ if Target = Convert_Ids (Ada.Task_Identification.Null_Task_Id) then
+ raise Program_Error with Error_Message & "null task";
+ end if;
+
+ if Task_Identification.Is_Terminated (T) then
+ raise Tasking_Error with Error_Message & "terminated task";
+ end if;
+
+ return Target.Common.Base_Priority;
+ end Get_Priority;
+
+ ------------------
+ -- Set_Priority --
+ ------------------
+
+ -- Change base priority of a task dynamically
+
+ procedure Set_Priority
+ (Priority : System.Any_Priority;
+ T : Ada.Task_Identification.Task_Id :=
+ Ada.Task_Identification.Current_Task)
+ is
+ Target : constant Task_Id := Convert_Ids (T);
+ Error_Message : constant String := "Trying to set the priority of a ";
+ Yield_Needed : Boolean;
+
+ begin
+ if Target = Convert_Ids (Ada.Task_Identification.Null_Task_Id) then
+ raise Program_Error with Error_Message & "null task";
+ end if;
+
+ -- Setting the priority of an already-terminated task doesn't do
+ -- anything (see RM-D.5.1(7)). Note that Get_Priority is different in
+ -- this regard.
+
+ if Task_Identification.Is_Terminated (T) then
+ return;
+ end if;
+
+ SSL.Abort_Defer.all;
+
+ if Single_Lock then
+ STPO.Lock_RTS;
+ end if;
+
+ STPO.Write_Lock (Target);
+
+ Target.Common.Base_Priority := Priority;
+
+ if Target.Common.Call /= null
+ and then
+ Target.Common.Call.Acceptor_Prev_Priority /= Priority_Not_Boosted
+ then
+ -- Target is within a rendezvous, so ensure the correct priority
+ -- will be reset when finishing the rendezvous, and only change the
+ -- priority immediately if the new priority is greater than the
+ -- current (inherited) priority.
+
+ Target.Common.Call.Acceptor_Prev_Priority := Priority;
+
+ if Priority >= Target.Common.Current_Priority then
+ Yield_Needed := True;
+ STPO.Set_Priority (Target, Priority);
+ else
+ Yield_Needed := False;
+ end if;
+
+ else
+ Yield_Needed := True;
+ STPO.Set_Priority (Target, Priority);
+
+ if Target.Common.State = Entry_Caller_Sleep then
+ Target.Pending_Priority_Change := True;
+ STPO.Wakeup (Target, Target.Common.State);
+ end if;
+ end if;
+
+ STPO.Unlock (Target);
+
+ if Single_Lock then
+ STPO.Unlock_RTS;
+ end if;
+
+ if STPO.Self = Target and then Yield_Needed then
+
+ -- Yield is needed to enforce FIFO task dispatching
+
+ -- LL Set_Priority is made while holding the RTS lock so that it is
+ -- inheriting high priority until it release all the RTS locks.
+
+ -- If this is used in a system where Ceiling Locking is not enforced
+ -- we may end up getting two Yield effects.
+
+ STPO.Yield;
+ end if;
+
+ SSL.Abort_Undefer.all;
+ end Set_Priority;
+
+end Ada.Dynamic_Priorities;