1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- A D A . D Y N A M I C _ P R I O R I T I E S --
9 -- Copyright (C) 1992-2005, Free Software Foundation, Inc. --
11 -- GNARL is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 2, or (at your option) any later ver- --
14 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNARL; see file COPYING. If not, write --
19 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
20 -- Boston, MA 02110-1301, USA. --
22 -- As a special exception, if other files instantiate generics from this --
23 -- unit, or you link this unit with other files to produce an executable, --
24 -- this unit does not by itself cause the resulting executable to be --
25 -- covered by the GNU General Public License. This exception does not --
26 -- however invalidate any other reasons why the executable file might be --
27 -- covered by the GNU Public License. --
29 -- GNARL was developed by the GNARL team at Florida State University. --
30 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
32 ------------------------------------------------------------------------------
34 with Ada
.Task_Identification
;
40 with System
.Task_Primitives
.Operations
;
41 -- used for Write_Lock
50 with System
.Parameters
;
51 -- used for Single_Lock
53 with System
.Soft_Links
;
54 -- use for Abort_Defer
57 with Unchecked_Conversion
;
59 package body Ada
.Dynamic_Priorities
is
61 package STPO
renames System
.Task_Primitives
.Operations
;
62 package SSL
renames System
.Soft_Links
;
64 use System
.Parameters
;
67 function Convert_Ids
is new
69 (Task_Identification
.Task_Id
, System
.Tasking
.Task_Id
);
75 -- Inquire base priority of a task
78 (T
: Ada
.Task_Identification
.Task_Id
:=
79 Ada
.Task_Identification
.Current_Task
) return System
.Any_Priority
81 Target
: constant Task_Id
:= Convert_Ids
(T
);
82 Error_Message
: constant String := "Trying to get the priority of a ";
85 if Target
= Convert_Ids
(Ada
.Task_Identification
.Null_Task_Id
) then
86 raise Program_Error
with Error_Message
& "null task";
89 if Task_Identification
.Is_Terminated
(T
) then
90 raise Tasking_Error
with Error_Message
& "null task";
93 return Target
.Common
.Base_Priority
;
100 -- Change base priority of a task dynamically
102 procedure Set_Priority
103 (Priority
: System
.Any_Priority
;
104 T
: Ada
.Task_Identification
.Task_Id
:=
105 Ada
.Task_Identification
.Current_Task
)
107 Target
: constant Task_Id
:= Convert_Ids
(T
);
108 Self_ID
: constant Task_Id
:= STPO
.Self
;
109 Error_Message
: constant String := "Trying to set the priority of a ";
112 if Target
= Convert_Ids
(Ada
.Task_Identification
.Null_Task_Id
) then
113 raise Program_Error
with Error_Message
& "null task";
116 if Task_Identification
.Is_Terminated
(T
) then
117 raise Tasking_Error
with Error_Message
& "terminated task";
126 STPO
.Write_Lock
(Target
);
128 if Self_ID
= Target
then
129 Target
.Common
.Base_Priority
:= Priority
;
130 STPO
.Set_Priority
(Target
, Priority
);
132 STPO
.Unlock
(Target
);
138 -- Yield is needed to enforce FIFO task dispatching
140 -- LL Set_Priority is made while holding the RTS lock so that it
141 -- is inheriting high priority until it release all the RTS locks.
143 -- If this is used in a system where Ceiling Locking is
144 -- not enforced we may end up getting two Yield effects.
149 Target
.New_Base_Priority
:= Priority
;
150 Target
.Pending_Priority_Change
:= True;
151 Target
.Pending_Action
:= True;
153 STPO
.Wakeup
(Target
, Target
.Common
.State
);
155 -- If the task is suspended, wake it up to perform the change.
156 -- check for ceiling violations ???
158 STPO
.Unlock
(Target
);
165 SSL
.Abort_Undefer
.all;
168 end Ada
.Dynamic_Priorities
;