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) 1991-2008, 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 -- This is a OpenVMS/Alpha version of this package
36 -- This package provides low-level support for most tasking features
39 -- Turn off polling, we do not want ATC polling to take place during tasking
40 -- operations. It causes infinite loops and other problems.
44 with System
.OS_Interface
;
47 package System
.Task_Primitives
is
50 type Lock
is limited private;
51 -- Should be used for implementation of protected objects
53 type RTS_Lock
is limited private;
54 -- Should be used inside the runtime system. The difference between Lock
55 -- and the RTS_Lock is that the later one serves only as a semaphore so
56 -- that do not check for ceiling violations.
58 type Suspension_Object
is limited private;
59 -- Should be used for the implementation of Ada.Synchronous_Task_Control
61 type Task_Body_Access
is access procedure;
62 -- Pointer to the task body's entry point (or possibly a wrapper
63 -- declared local to the GNARL).
65 type Private_Data
is limited private;
66 -- Any information that the GNULLI needs maintained on a per-task basis.
67 -- A component of this type is guaranteed to be included in the
68 -- Ada_Task_Control_Block.
70 subtype Task_Address
is System
.Aux_DEC
.Short_Address
;
71 -- Task_Address is the short version of address defined in System.Aux_DEC.
72 -- To avoid dragging Aux_DEC into tasking packages a tasking specific
73 -- subtype is defined here.
75 Task_Address_Size
: constant := System
.Aux_DEC
.Short_Address_Size
;
76 -- The size of Task_Address
78 Alternate_Stack_Size
: constant := 0;
79 -- No alternate signal stack is used on this platform
83 type Exc_Stack_T
is array (0 .. 8192) of aliased Character;
84 for Exc_Stack_T
'Alignment use Standard
'Maximum_Alignment;
85 type Exc_Stack_Ptr_T
is access all Exc_Stack_T
;
88 L
: aliased System
.OS_Interface
.pthread_mutex_t
;
89 Prio
: Interfaces
.C
.int
;
90 Prio_Save
: Interfaces
.C
.int
;
93 type RTS_Lock
is new System
.OS_Interface
.pthread_mutex_t
;
95 type Suspension_Object
is record
97 pragma Atomic
(State
);
98 -- Boolean that indicates whether the object is open. This field is
99 -- marked Atomic to ensure that we can read its value without locking
100 -- the access to the Suspension_Object.
103 -- Flag showing if there is a task already suspended on this object
105 L
: aliased System
.OS_Interface
.pthread_mutex_t
;
106 -- Protection for ensuring mutual exclusion on the Suspension_Object
108 CV
: aliased System
.OS_Interface
.pthread_cond_t
;
109 -- Condition variable used to queue threads until ondition is signaled
112 type Private_Data
is record
113 Thread
: aliased System
.OS_Interface
.pthread_t
;
114 pragma Atomic
(Thread
);
115 -- Thread field may be updated by two different threads of control.
116 -- (See, Enter_Task and Create_Task in s-taprop.adb). They put the
117 -- same value (thr_self value). We do not want to use lock on those
118 -- operations and the only thing we have to make sure is that they
119 -- are updated in atomic fashion.
121 CV
: aliased System
.OS_Interface
.pthread_cond_t
;
123 L
: aliased RTS_Lock
;
124 -- Protection for all components is lock L
126 Exc_Stack_Ptr
: Exc_Stack_Ptr_T
;
127 -- ??? This needs comments
129 AST_Pending
: Boolean;
130 -- Used to detect delay and sleep timeouts
134 end System
.Task_Primitives
;