gcc/ada/a-synbar.adb

   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.         --
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  11 -- This specification is derived from the Ada Reference Manual for use with --
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  32 -- Extensive contributions were provided by Ada Core Technologies Inc.      --
  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 package body Ada.Synchronous_Barriers is
  37
  38    protected body Synchronous_Barrier is
  39       --  The condition "Wait'Count = Release_Threshold" opens the barrier when
  40       --  the required number of tasks is reached. The condition "Keep_Open"
  41       --  leaves the barrier open while there are queued tasks. While there are
  42       --  tasks in the queue no new task will be queued, guaranteeing that the
  43       --  barrier will remain open only for those tasks already inside.
  44
  45       entry Wait (Notified : out Boolean)
  46         when Wait'Count = Release_Threshold or else Keep_Open is
  47       begin
  48          --  If we are executing the entry it means that the required number
  49          --  of tasks have been queued in the entry. Keep_Open barrier will
  50          --  remain true until all queued tasks are out.
  51
  52          Keep_Open := Wait'Count > 0;
  53
  54          --  The last released task will close the barrier and get the
  55          --  Notified token.
  56
  57          Notified := Wait'Count = 0;
  58       end Wait;
  59    end Synchronous_Barrier;
  60
  61    ----------------------
  62    -- Wait_For_Release --
  63    ----------------------
  64
  65    procedure Wait_For_Release
  66      (The_Barrier : in out Synchronous_Barrier;
  67       Notified    : out    Boolean) is
  68    begin
  69       The_Barrier.Wait (Notified);
  70    end Wait_For_Release;
  71 end Ada.Synchronous_Barriers;