gcc/ada/a-synbar-posix.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT RUN-TIME COMPONENTS                         --
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   5 --             A D A . S Y N C H R O N O U S _ B A R R I E R S              --
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  33 --                                                                          --
  34 ------------------------------------------------------------------------------
  35
  36 --  This is the body of this package using POSIX barriers
  37
  38 with Interfaces.C; use Interfaces.C;
  39
  40 package body Ada.Synchronous_Barriers is
  41
  42    --------------------
  43    -- POSIX barriers --
  44    --------------------
  45
  46    function pthread_barrier_init
  47      (barrier : not null access pthread_barrier_t;
  48       attr    : System.Address := System.Null_Address;
  49       count   : unsigned) return int;
  50    pragma Import (C, pthread_barrier_init, "pthread_barrier_init");
  51    --  Initialize barrier with the attributes in attr. The barrier is opened
  52    --  when count waiters arrived. If attr is null the default barrier
  53    --  attributes are used.
  54
  55    function pthread_barrier_destroy
  56      (barrier : not null access pthread_barrier_t) return int;
  57    pragma Import (C, pthread_barrier_destroy, "pthread_barrier_destroy");
  58    --  Destroy a previously dynamically initialized barrier
  59
  60    function pthread_barrier_wait
  61      (barrier : not null access pthread_barrier_t) return int;
  62    pragma Import (C, pthread_barrier_wait, "pthread_barrier_wait");
  63    --  Wait on barrier
  64
  65    --------------
  66    -- Finalize --
  67    --------------
  68
  69    overriding procedure Finalize (Barrier : in out Synchronous_Barrier) is
  70       Result : int;
  71    begin
  72       Result := pthread_barrier_destroy (Barrier.POSIX_Barrier'Access);
  73       pragma Assert (Result = 0);
  74    end Finalize;
  75
  76    overriding procedure Initialize (Barrier : in out Synchronous_Barrier) is
  77       Result : int;
  78    begin
  79       Result :=
  80         pthread_barrier_init
  81           (barrier => Barrier.POSIX_Barrier'Access,
  82            attr    => System.Null_Address,
  83            count   => unsigned (Barrier.Release_Threshold));
  84       pragma Assert (Result = 0);
  85    end Initialize;
  86
  87    ----------------------
  88    -- Wait_For_Release --
  89    ----------------------
  90
  91    procedure Wait_For_Release
  92      (The_Barrier : in out Synchronous_Barrier;
  93       Notified    : out Boolean)
  94    is
  95       Result : int;
  96
  97       PTHREAD_BARRIER_SERIAL_THREAD : constant := -1;
  98       --  Value used to indicate the task which receives the notification for
  99       --  the barrier open.
 100
 101    begin
 102       Result :=
 103         pthread_barrier_wait
 104           (barrier => The_Barrier.POSIX_Barrier'Access);
 105       pragma Assert
 106         (Result = 0 or else Result = PTHREAD_BARRIER_SERIAL_THREAD);
 107
 108       Notified := (Result = PTHREAD_BARRIER_SERIAL_THREAD);
 109    end Wait_For_Release;
 110
 111 end Ada.Synchronous_Barriers;