1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
------------------------------------------------------------------------------
-- --
-- GNU ADA 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) 1992-2004, 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- --
-- 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. --
-- Extensive contributions were provided by Ada Core Technologies, Inc. --
-- --
------------------------------------------------------------------------------
with Ada.Task_Identification;
-- used for Task_Id
-- Current_Task
-- Null_Task_Id
-- Is_Terminated
with System.Task_Primitives.Operations;
-- used for Write_Lock
-- Unlock
-- Set_Priority
-- Wakeup
-- Self
with System.Tasking;
-- used for Task_Id
with Ada.Exceptions;
-- used for Raise_Exception
with System.Tasking.Initialization;
-- used for Defer/Undefer_Abort
with System.Parameters;
-- used for Single_Lock
with Unchecked_Conversion;
package body Ada.Dynamic_Priorities is
package STPO renames System.Task_Primitives.Operations;
use System.Parameters;
use System.Tasking;
use Ada.Exceptions;
function Convert_Ids is new
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_Exception (Program_Error'Identity,
Error_Message & "null task");
end if;
if Task_Identification.Is_Terminated (T) then
Raise_Exception (Tasking_Error'Identity,
Error_Message & "null 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);
Self_ID : constant Task_Id := STPO.Self;
Error_Message : constant String := "Trying to set the priority of a ";
begin
if Target = Convert_Ids (Ada.Task_Identification.Null_Task_Id) then
Raise_Exception (Program_Error'Identity,
Error_Message & "null task");
end if;
if Task_Identification.Is_Terminated (T) then
Raise_Exception (Tasking_Error'Identity,
Error_Message & "terminated task");
end if;
Initialization.Defer_Abort (Self_ID);
if Single_Lock then
STPO.Lock_RTS;
end if;
STPO.Write_Lock (Target);
if Self_ID = Target then
Target.Common.Base_Priority := Priority;
STPO.Set_Priority (Target, Priority);
STPO.Unlock (Target);
if Single_Lock then
STPO.Unlock_RTS;
end if;
-- 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;
else
Target.New_Base_Priority := Priority;
Target.Pending_Priority_Change := True;
Target.Pending_Action := True;
STPO.Wakeup (Target, Target.Common.State);
-- If the task is suspended, wake it up to perform the change.
-- check for ceiling violations ???
STPO.Unlock (Target);
if Single_Lock then
STPO.Unlock_RTS;
end if;
end if;
Initialization.Undefer_Abort (Self_ID);
end Set_Priority;
end Ada.Dynamic_Priorities;
|
