gcc/ada/libgnarl/a-synbar.adb

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  34 ------------------------------------------------------------------------------
  35
  36 package body Ada.Synchronous_Barriers with SPARK_Mode => Off 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
  78 end Ada.Synchronous_Barriers;