1 ------------------------------------------------------------------------------
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . T A S K _ P R I M I T I V E S --
9 -- Copyright (C) 1991-1994, Florida State University --
10 -- Copyright (C) 1995-2005, AdaCore --
12 -- GNARL is free software; you can redistribute it and/or modify it under --
13 -- terms of the GNU General Public License as published by the Free Soft- --
14 -- ware Foundation; either version 2, or (at your option) any later ver- --
15 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
16 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
17 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
18 -- for more details. You should have received a copy of the GNU General --
19 -- Public License distributed with GNARL; see file COPYING. If not, write --
20 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
21 -- Boston, MA 02110-1301, USA. --
23 -- As a special exception, if other files instantiate generics from this --
24 -- unit, or you link this unit with other files to produce an executable, --
25 -- this unit does not by itself cause the resulting executable to be --
26 -- covered by the GNU General Public License. This exception does not --
27 -- however invalidate any other reasons why the executable file might be --
28 -- covered by the GNU Public License. --
30 -- GNARL was developed by the GNARL team at Florida State University. --
31 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
33 ------------------------------------------------------------------------------
35 -- This is an OS/2 version of this package
37 -- This package provides low-level support for most tasking features
40 -- Turn off polling, we do not want ATC polling to take place during
41 -- tasking operations. It causes infinite loops and other problems.
43 with Interfaces
.OS2Lib
.Threads
;
44 with Interfaces
.OS2Lib
.Synchronization
;
46 package System
.Task_Primitives
is
49 type Lock
is limited private;
50 -- Should be used for implementation of protected objects.
52 type RTS_Lock
is limited private;
53 -- Should be used inside the runtime system.
54 -- The difference between Lock and the RTS_Lock is that the later
55 -- one serves only as a semaphore so that do not check for
56 -- ceiling violations.
58 type Task_Body_Access
is access procedure;
59 -- Pointer to the task body's entry point (or possibly a wrapper
60 -- declared local to the GNARL).
62 type Private_Data
is limited private;
63 -- Any information that the GNULLI needs maintained on a per-task
64 -- basis. A component of this type is guaranteed to be included
65 -- in the Ada_Task_Control_Block.
70 Mutex
: aliased Interfaces
.OS2Lib
.Synchronization
.HMTX
;
72 Owner_Priority
: Integer;
76 type RTS_Lock
is new Lock
;
78 type Suspension_Object
is record
80 pragma Atomic
(State
);
81 -- Boolean that indicates whether the object is open. This field is
82 -- marked Atomic to ensure that we can read its value without locking
83 -- the access to the Suspension_Object.
86 -- Flag showing if there is a task already suspended on this object
88 L
: aliased Interfaces
.OS2Lib
.Synchronization
.HMTX
;
89 -- Protection for ensuring mutual exclusion on the Suspension_Object
91 CV
: aliased Interfaces
.OS2Lib
.Synchronization
.HEV
;
92 -- Condition variable used to queue threads until condition is signaled
95 type Private_Data
is record
96 Thread
: aliased Interfaces
.OS2Lib
.Threads
.TID
;
97 pragma Atomic
(Thread
);
98 -- Thread field may be updated by two different threads of control.
99 -- (See, Enter_Task and Create_Task in s-taprop.adb). They put the same
100 -- value (thr_self value). We do not want to use lock on those
101 -- operations and the only thing we have to make sure is that they are
102 -- updated in atomic fashion.
104 CV
: aliased Interfaces
.OS2Lib
.Synchronization
.HEV
;
106 L
: aliased RTS_Lock
;
107 -- Protection for all components is lock L
109 Current_Priority
: Integer := -1;
110 -- The Current_Priority is the actual priority of a thread. This field
111 -- is needed because it is only possible to set delta priority in OS/2.
112 -- The only places where this field should be set are Set_Priority,
113 -- Create_Task and Initialize (Environment).
115 Wrapper
: Interfaces
.OS2Lib
.Threads
.PFNTHREAD
;
116 -- This is the original wrapper passed by Operations.Create_Task. When
117 -- installing an exception handler in a thread, the thread starts
118 -- executing the Exception_Wrapper which calls Wrapper when the handler
119 -- has been installed. The handler is removed when wrapper returns.
122 end System
.Task_Primitives
;