1 ------------------------------------------------------------------------------
3 -- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
5 -- S Y S T E M . T A S K I N G . R E S T R I C T E D . S T A G E S --
11 -- Copyright (C) 1992-1999, Free Software Foundation, Inc. --
13 -- GNARL is free software; you can redistribute it and/or modify it under --
14 -- terms of the GNU General Public License as published by the Free Soft- --
15 -- ware Foundation; either version 2, or (at your option) any later ver- --
16 -- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
17 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
18 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
19 -- for more details. You should have received a copy of the GNU General --
20 -- Public License distributed with GNARL; see file COPYING. If not, write --
21 -- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
22 -- MA 02111-1307, USA. --
24 -- As a special exception, if other files instantiate generics from this --
25 -- unit, or you link this unit with other files to produce an executable, --
26 -- this unit does not by itself cause the resulting executable to be --
27 -- covered by the GNU General Public License. This exception does not --
28 -- however invalidate any other reasons why the executable file might be --
29 -- covered by the GNU Public License. --
31 -- GNARL was developed by the GNARL team at Florida State University. It is --
32 -- now maintained by Ada Core Technologies Inc. in cooperation with Florida --
33 -- State University (http://www.gnat.com). --
35 ------------------------------------------------------------------------------
37 -- This is a simplified version of the System.Tasking.Stages package,
38 -- intended to be used in a restricted run time.
40 -- This package represents the high level tasking interface used by the
41 -- compiler to expand Ada 95 tasking constructs into simpler run time calls
42 -- (aka GNARLI, GNU Ada Run-time Library Interface)
44 -- Note: the compiler generates direct calls to this interface, via Rtsfind.
45 -- Any changes to this interface may require corresponding compiler changes
46 -- in exp_ch9.adb and possibly exp_ch7.adb
48 -- The restricted GNARLI is also composed of System.Protected_Objects and
49 -- System.Protected_Objects.Single_Entry
51 with System.Task_Info;
52 -- used for Task_Info_Type
54 with System.Parameters;
57 package System.Tasking.Restricted.Stages is
58 pragma Elaborate_Body;
60 ---------------------------------
61 -- Compiler Interface (GNARLI) --
62 ---------------------------------
64 -- The compiler will expand in the GNAT tree the following construct:
66 -- task type T (Discr : Integer);
69 -- ...declarations, possibly some controlled...
78 -- task type t (discr : integer);
79 -- tE : aliased boolean := false;
80 -- tZ : size_type := unspecified_size;
81 -- type tV (discr : integer) is limited record
82 -- _task_id : task_id;
84 -- procedure tB (_task : access tV);
86 -- procedure _init_proc (_init : in out tV; _master : master_id;
87 -- _chain : in out activation_chain; _task_id : in task_image_type;
88 -- discr : integer) is
90 -- _init.discr := discr;
91 -- _init._task_id := null;
92 -- create_restricted_task (unspecified_priority, tZ,
93 -- unspecified_task_info, task_procedure_access!(tB'address),
94 -- _init'address, tE'unchecked_access, _chain, _task_id, _init.
100 -- _chain : aliased activation_chain;
101 -- _init_proc (_chain);
103 -- procedure tB (_task : access tV) is
104 -- discr : integer renames _task.discr;
106 -- procedure _clean is
108 -- complete_restricted_task;
109 -- finalize_list (F14b);
113 -- ...declarations...
114 -- complete_restricted_activation;
123 -- t1I : task_image_type := new string'"t1";
124 -- _init_proc (t1, 3, _chain, t1I, 1);
126 -- activate_restricted_tasks (_chain'unchecked_access);
128 procedure Create_Restricted_Task
130 Size : System.Parameters.Size_Type;
131 Task_Info : System.Task_Info.Task_Info_Type;
132 State : Task_Procedure_Access;
133 Discriminants : System.Address;
134 Elaborated : Access_Boolean;
135 Chain : in out Activation_Chain;
136 Task_Image : System.Task_Info.Task_Image_Type;
137 Created_Task : out Task_ID);
138 -- Compiler interface only. Do not call from within the RTS.
139 -- This must be called to create a new task.
141 -- Priority is the task's priority (assumed to be in the
142 -- System.Any_Priority'Range)
143 -- Size is the stack size of the task to create
144 -- Task_Info is the task info associated with the created task, or
145 -- Unspecified_Task_Info if none.
146 -- State is the compiler generated task's procedure body
147 -- Discriminants is a pointer to a limited record whose discriminants
148 -- are those of the task to create. This parameter should be passed as
149 -- the single argument to State.
150 -- Elaborated is a pointer to a Boolean that must be set to true on exit
151 -- if the task could be successfully elaborated.
152 -- Chain is a linked list of task that needs to be created. On exit,
153 -- Created_Task.Activation_Link will be Chain.T_ID, and Chain.T_ID
154 -- will be Created_Task (e.g the created task will be linked at the front
156 -- Task_Image is a pointer to a string created by the compiler that the
157 -- run time can store to ease the debugging and the
158 -- Ada.Task_Identification facility.
159 -- Created_Task is the resulting task.
161 -- This procedure can raise Storage_Error if the task creation failed.
163 procedure Activate_Restricted_Tasks
164 (Chain_Access : Activation_Chain_Access);
165 -- Compiler interface only. Do not call from within the RTS.
166 -- This must be called by the creator of a chain of one or more new tasks,
167 -- to activate them. The chain is a linked list that up to this point is
168 -- only known to the task that created them, though the individual tasks
169 -- are already in the All_Tasks_List.
171 -- The compiler builds the chain in LIFO order (as a stack). Another
172 -- version of this procedure had code to reverse the chain, so as to
173 -- activate the tasks in the order of declaration. This might be nice, but
174 -- it is not needed if priority-based scheduling is supported, since all
175 -- the activated tasks synchronize on the activators lock before they
176 -- start activating and so they should start activating in priority order.
178 procedure Complete_Restricted_Activation;
179 -- Compiler interface only. Do not call from within the RTS.
180 -- This should be called from the task body at the end of
181 -- the elaboration code for its declarative part.
182 -- Decrement the count of tasks to be activated by the activator and
183 -- wake it up so it can check to see if all tasks have been activated.
184 -- Except for the environment task, which should never call this procedure,
185 -- T.Activator should only be null iff T has completed activation.
187 procedure Complete_Restricted_Task;
188 -- Compiler interface only. Do not call from within the RTS.
189 -- This should be called from an implicit at-end handler
190 -- associated with the task body, when it completes.
191 -- From this point, the current task will become not callable.
192 -- If the current task have not completed activation, this should be done
193 -- now in order to wake up the activator (the environment task).
195 function Restricted_Terminated (T : Task_ID) return Boolean;
196 -- Compiler interface only. Do not call from within the RTS.
197 -- This is called by the compiler to implement the 'Terminated attribute.
203 -- restricted_terminated (t1._task_id)
205 procedure Finalize_Global_Tasks;
206 -- This is needed to support the compiler interface; it will only be called
207 -- by the Environment task in the binder generated file (by adafinal).
208 -- Instead, it will cause the Environment to block forever, since none of
209 -- the dependent tasks are expected to terminate
211 end System.Tasking.Restricted.Stages;