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) 1991-2011, 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 3, or (at your option) any later ver- --
14 -- sion. GNAT 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. --
18 -- As a special exception under Section 7 of GPL version 3, you are granted --
19 -- additional permissions described in the GCC Runtime Library Exception, --
20 -- version 3.1, as published by the Free Software Foundation. --
22 -- You should have received a copy of the GNU General Public License and --
23 -- a copy of the GCC Runtime Library Exception along with this program; --
24 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
25 -- <http://www.gnu.org/licenses/>. --
27 -- GNARL was developed by the GNARL team at Florida State University. --
28 -- Extensive contributions were provided by Ada Core Technologies, Inc. --
30 ------------------------------------------------------------------------------
32 -- This is a OpenVMS/Alpha version of this package
34 -- This package provides low-level support for most tasking features
37 -- Turn off polling, we do not want ATC polling to take place during tasking
38 -- operations. It causes infinite loops and other problems.
42 with System
.OS_Interface
;
45 package System
.Task_Primitives
is
48 type Lock
is limited private;
49 -- Should be used for implementation of protected objects
51 type RTS_Lock
is limited private;
52 -- Should be used inside the runtime system. The difference between Lock
53 -- and the RTS_Lock is that the later one serves only as a semaphore so
54 -- that do not check for ceiling violations.
56 type Suspension_Object
is limited private;
57 -- Should be used for the implementation of Ada.Synchronous_Task_Control
59 type Task_Body_Access
is access procedure;
60 -- Pointer to the task body's entry point (or possibly a wrapper
61 -- declared local to the GNARL).
63 type Private_Data
is limited private;
64 -- Any information that the GNULLI needs maintained on a per-task basis.
65 -- A component of this type is guaranteed to be included in the
66 -- Ada_Task_Control_Block.
68 subtype Task_Address
is System
.Aux_DEC
.Short_Address
;
69 -- Task_Address is the short version of address defined in System.Aux_DEC.
70 -- To avoid dragging Aux_DEC into tasking packages a tasking specific
71 -- subtype is defined here.
73 Task_Address_Size
: constant := System
.Aux_DEC
.Short_Address_Size
;
74 -- The size of Task_Address
76 Alternate_Stack_Size
: constant := 0;
77 -- No alternate signal stack is used on this platform
82 L
: aliased System
.OS_Interface
.pthread_mutex_t
;
83 Prio
: Interfaces
.C
.int
;
84 Prio_Save
: Interfaces
.C
.int
;
87 type RTS_Lock
is new System
.OS_Interface
.pthread_mutex_t
;
89 type Suspension_Object
is record
91 pragma Atomic
(State
);
92 -- Boolean that indicates whether the object is open. This field is
93 -- marked Atomic to ensure that we can read its value without locking
94 -- the access to the Suspension_Object.
97 -- Flag showing if there is a task already suspended on this object
99 L
: aliased System
.OS_Interface
.pthread_mutex_t
;
100 -- Protection for ensuring mutual exclusion on the Suspension_Object
102 CV
: aliased System
.OS_Interface
.pthread_cond_t
;
103 -- Condition variable used to queue threads until ondition is signaled
106 type Private_Data
is record
107 Thread
: aliased System
.OS_Interface
.pthread_t
;
108 pragma Atomic
(Thread
);
109 -- Thread field may be updated by two different threads of control.
110 -- (See, Enter_Task and Create_Task in s-taprop.adb). They put the
111 -- same value (thr_self value). We do not want to use lock on those
112 -- operations and the only thing we have to make sure is that they
113 -- are updated in atomic fashion.
115 CV
: aliased System
.OS_Interface
.pthread_cond_t
;
117 L
: aliased RTS_Lock
;
118 -- Protection for all components is lock L
120 AST_Pending
: Boolean;
121 -- Used to detect delay and sleep timeouts
125 end System
.Task_Primitives
;