1------------------------------------------------------------------------------ 2-- -- 3-- GNAT RUN-TIME COMPONENTS -- 4-- -- 5-- A D A . S Y N C H R O N O U S _ B A R R I E R S -- 6-- -- 7-- B o d y -- 8-- -- 9-- Copyright (C) 1992-2011, Free Software Foundation, Inc. -- 10-- -- 11-- This specification is derived from the Ada Reference Manual for use with -- 12-- GNAT. The copyright notice above, and the license provisions that follow -- 13-- apply solely to the contents of the part following the private keyword. -- 14-- -- 15-- GNAT is free software; you can redistribute it and/or modify it under -- 16-- terms of the GNU General Public License as published by the Free Soft- -- 17-- ware Foundation; either version 3, or (at your option) any later ver- -- 18-- sion. GNAT is distributed in the hope that it will be useful, but WITH- -- 19-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY -- 20-- or FITNESS FOR A PARTICULAR PURPOSE. -- 21-- -- 22-- As a special exception under Section 7 of GPL version 3, you are granted -- 23-- additional permissions described in the GCC Runtime Library Exception, -- 24-- version 3.1, as published by the Free Software Foundation. -- 25-- -- 26-- You should have received a copy of the GNU General Public License and -- 27-- a copy of the GCC Runtime Library Exception along with this program; -- 28-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see -- 29-- <http://www.gnu.org/licenses/>. -- 30-- -- 31-- GNAT was originally developed by the GNAT team at New York University. -- 32-- Extensive contributions were provided by Ada Core Technologies Inc. -- 33-- -- 34------------------------------------------------------------------------------ 35 36package body Ada.Synchronous_Barriers is 37 38 protected body Synchronous_Barrier is 39 40 -- The condition "Wait'Count = Release_Threshold" opens the barrier when 41 -- the required number of tasks is reached. The condition "Keep_Open" 42 -- leaves the barrier open while there are queued tasks. While there are 43 -- tasks in the queue no new task will be queued (no new protected 44 -- action can be started on a protected object while another protected 45 -- action on the same protected object is underway, RM 9.5.1 (4)), 46 -- guaranteeing that the barrier will remain open only for those tasks 47 -- already inside the queue when the barrier was open. 48 49 entry Wait (Notified : out Boolean) 50 when Keep_Open or else Wait'Count = Release_Threshold 51 is 52 begin 53 -- If we are executing the entry it means that the required number of 54 -- tasks have been queued in the entry. Keep_Open barrier will remain 55 -- true until all queued tasks are out. 56 57 Keep_Open := Wait'Count > 0; 58 59 -- The last released task will close the barrier and get the Notified 60 -- token. 61 62 Notified := Wait'Count = 0; 63 end Wait; 64 end Synchronous_Barrier; 65 66 ---------------------- 67 -- Wait_For_Release -- 68 ---------------------- 69 70 procedure Wait_For_Release 71 (The_Barrier : in out Synchronous_Barrier; 72 Notified : out Boolean) 73 is 74 begin 75 The_Barrier.Wait (Notified); 76 end Wait_For_Release; 77 78end Ada.Synchronous_Barriers; 79