1------------------------------------------------------------------------------
2--                                                                          --
3--                  GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                --
4--                                                                          --
5--                 S Y S T E M . T A S K _ P R I M I T I V E S              --
6--                                                                          --
7--                                  S p e c                                 --
8--                                                                          --
9--          Copyright (C) 1992-2011, Free Software Foundation, Inc.         --
10--                                                                          --
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.                                     --
17--                                                                          --
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.               --
21--                                                                          --
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/>.                                          --
26--                                                                          --
27-- GNARL was developed by the GNARL team at Florida State University.       --
28-- Extensive contributions were provided by Ada Core Technologies, Inc.     --
29--                                                                          --
30------------------------------------------------------------------------------
31
32--  This is a Solaris version of this package
33
34--  This package provides low-level support for most tasking features
35
36pragma Polling (Off);
37--  Turn off polling, we do not want ATC polling to take place during tasking
38--  operations. It causes infinite loops and other problems.
39
40with Ada.Unchecked_Conversion;
41
42with System.OS_Interface;
43
44package System.Task_Primitives is
45   pragma Preelaborate;
46
47   type Lock is limited private;
48   type Lock_Ptr is access all Lock;
49   --  Should be used for implementation of protected objects
50
51   type RTS_Lock is limited private;
52   type RTS_Lock_Ptr is access all RTS_Lock;
53   --  Should be used inside the runtime system. The difference between Lock
54   --  and the RTS_Lock is that the later one serves only as a semaphore so
55   --  that do not check for ceiling violations.
56
57   function To_Lock_Ptr is
58     new Ada.Unchecked_Conversion (RTS_Lock_Ptr, Lock_Ptr);
59
60   type Suspension_Object is limited private;
61   --  Should be used for the implementation of Ada.Synchronous_Task_Control
62
63   type Task_Body_Access is access procedure;
64   --  Pointer to the task body's entry point (or possibly a wrapper
65   --  declared local to the GNARL).
66
67   type Private_Data is limited private;
68   --  Any information that the GNULLI needs maintained on a per-task basis.
69   --  A component of this type is guaranteed to be included in the
70   --  Ada_Task_Control_Block.
71
72   subtype Task_Address is System.Address;
73   --  In some versions of Task_Primitives, notably for VMS, Task_Address is
74   --  the short version of address defined in System.Aux_DEC. To avoid
75   --  dragging Aux_DEC into tasking packages a tasking specific subtype is
76   --  defined here.
77
78   Task_Address_Size : constant := Standard'Address_Size;
79   --  The size of Task_Address
80
81   Alternate_Stack_Size : constant := 0;
82   --  No alternate signal stack is used on this platform
83
84private
85
86   type Private_Task_Serial_Number is mod 2 ** 64;
87   --  Used to give each task a unique serial number
88
89   type Base_Lock is new System.OS_Interface.mutex_t;
90
91   type Owner_Int is new Integer;
92   for Owner_Int'Alignment use Standard'Maximum_Alignment;
93
94   type Owner_ID is access all Owner_Int;
95
96   function To_Owner_ID is
97     new Ada.Unchecked_Conversion (System.Address, Owner_ID);
98
99   type Lock is record
100      L              : aliased Base_Lock;
101      Ceiling        : System.Any_Priority := System.Any_Priority'First;
102      Saved_Priority : System.Any_Priority :=  System.Any_Priority'First;
103      Owner          : Owner_ID;
104      Next           : Lock_Ptr;
105      Level          : Private_Task_Serial_Number := 0;
106      Buddy          : Owner_ID;
107      Frozen         : Boolean := False;
108   end record;
109
110   type RTS_Lock is new Lock;
111
112   type Suspension_Object is record
113      State : Boolean;
114      pragma Atomic (State);
115      --  Boolean that indicates whether the object is open. This field is
116      --  marked Atomic to ensure that we can read its value without locking
117      --  the access to the Suspension_Object.
118
119      Waiting : Boolean;
120      --  Flag showing if there is a task already suspended on this object
121
122      L : aliased System.OS_Interface.mutex_t;
123      --  Protection for ensuring mutual exclusion on the Suspension_Object
124
125      CV : aliased System.OS_Interface.cond_t;
126      --  Condition variable used to queue threads until condition is signaled
127   end record;
128
129   --  Note that task support on gdb relies on the fact that the first two
130   --  fields of Private_Data are Thread and LWP.
131
132   type Private_Data is record
133      Thread : aliased System.OS_Interface.thread_t;
134      pragma Atomic (Thread);
135      --  Thread field may be updated by two different threads of control.
136      --  (See, Enter_Task and Create_Task in s-taprop.adb). They put the same
137      --  value (thr_self value). We do not want to use lock on those
138      --  operations and the only thing we have to make sure is that they are
139      --  updated in atomic fashion.
140
141      LWP : System.OS_Interface.lwpid_t;
142      --  The LWP id of the thread. Set by self in Enter_Task
143
144      CV : aliased System.OS_Interface.cond_t;
145      L  : aliased RTS_Lock;
146      --  Protection for all components is lock L
147
148      Active_Priority : System.Any_Priority := System.Any_Priority'First;
149      --  Simulated active priority, used iff Priority_Ceiling_Support is True
150
151      Locking : Lock_Ptr;
152      Locks   : Lock_Ptr;
153      Wakeups : Natural := 0;
154   end record;
155
156end System.Task_Primitives;
157