Implement -mmemcpy-strategy= and -mmemset-strategy= options
[official-gcc.git] / gcc / ada / s-taasde.ads
blob97a93b9ad5d760c1bf42f405bd7b2430ec8eed20
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
4 -- --
5 -- S Y S T E M . T A S K I N G . A S Y N C _ D E L A Y S --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 1998-2009, 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 ------------------------------------------------------------------------------
32 -- This package contains the procedures to implements timeouts (delays) for
33 -- asynchronous select statements.
35 -- Note: the compiler generates direct calls to this interface, via Rtsfind.
36 -- Any changes to this interface may require corresponding compiler changes.
38 package System.Tasking.Async_Delays is
40 -- Suppose the following source code is given:
42 -- select delay When;
43 -- ...continuation for timeout case...
44 -- then abort
45 -- ...abortable part...
46 -- end select;
48 -- The compiler should expand this to the following:
50 -- declare
51 -- DB : aliased Delay_Block;
52 -- begin
53 -- if System.Tasking.Async_Delays.Enqueue_Duration
54 -- (When, DB'Unchecked_Access)
55 -- then
56 -- begin
57 -- A101b : declare
58 -- procedure _clean is
59 -- begin
60 -- System.Tasking.Async_Delays.Cancel_Async_Delay
61 -- (DB'Unchecked_Access);
62 -- return;
63 -- end _clean;
64 -- begin
65 -- abort_undefer.all;
66 -- ...abortable part...
67 -- exception
68 -- when all others =>
69 -- declare
70 -- E105b : exception_occurrence;
71 -- begin
72 -- save_occurrence (E105b, get_current_excep.all.all);
73 -- _clean;
74 -- reraise_occurrence_no_defer (E105b);
75 -- end;
76 -- at end
77 -- _clean;
78 -- end A101b;
79 -- exception
80 -- when _abort_signal =>
81 -- abort_undefer.all;
82 -- end;
83 -- end if;
85 -- if Timed_Out (DB'Unchecked_Access) then
86 -- ...continuation for timeout case...
87 -- end if;
88 -- end;
90 -----------------
91 -- Delay_Block --
92 -----------------
94 type Delay_Block is limited private;
95 type Delay_Block_Access is access all Delay_Block;
97 function Enqueue_Duration
98 (T : Duration;
99 D : Delay_Block_Access) return Boolean;
100 -- Enqueue the specified relative delay. Returns True if the delay has
101 -- been enqueued, False if it has already expired. If the delay has been
102 -- enqueued, abort is deferred.
104 procedure Cancel_Async_Delay (D : Delay_Block_Access);
105 -- Cancel the specified asynchronous delay
107 function Timed_Out (D : Delay_Block_Access) return Boolean;
108 pragma Inline (Timed_Out);
109 -- Return True if the delay specified in D has timed out
111 -- There are child units for delays on Ada.Calendar.Time and
112 -- Ada.Real_Time.Time, so that an application will not need to link in
113 -- features that is not using.
115 private
117 type Delay_Block is record
118 Self_Id : Task_Id;
119 -- ID of the calling task
121 Level : ATC_Level_Base;
122 -- Normally Level is the ATC nesting level of the
123 -- async. select statement to which this delay belongs, but
124 -- after a call has been dequeued we set it to
125 -- ATC_Level_Infinity so that the Cancel operation can
126 -- detect repeated calls, and act idempotently.
128 Resume_Time : Duration;
129 -- The absolute wake up time, represented as Duration
131 Timed_Out : Boolean := False;
132 -- Set to true if the delay has timed out
134 Succ, Pred : Delay_Block_Access;
135 -- A double linked list
136 end record;
138 -- The above "overlaying" of Self_ID and Level to hold other
139 -- data that has a non-overlapping lifetime is an unabashed
140 -- hack to save memory.
142 procedure Time_Enqueue
143 (T : Duration;
144 D : Delay_Block_Access);
145 pragma Inline (Time_Enqueue);
146 -- Used by the child units to enqueue delays on the timer queue
147 -- implemented in the body of this package.
149 end System.Tasking.Async_Delays;