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------------------------------------------------------------------------------

--                                                                          --

--                 GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS                 --

--                                                                          --

--     S Y S T E M . T A S K _ P R I M I T I V E S . O P E R A T I O N S    --

--                                                                          --

--                                  B o d y                                 --

--                                                                          --

--         Copyright (C) 1992-2011, Free Software Foundation, Inc.          --

--                                                                          --

-- GNARL is free software; you can  redistribute it  and/or modify it under --

-- terms of the  GNU General Public License as published  by the Free Soft- --

-- ware  Foundation;  either version 3,  or (at your option) any later ver- --

-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --

-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --

-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --

--                                                                          --

-- As a special exception under Section 7 of GPL version 3, you are granted --

-- additional permissions described in the GCC Runtime Library Exception,   --

-- version 3.1, as published by the Free Software Foundation.               --

--                                                                          --

-- You should have received a copy of the GNU General Public License and    --

-- a copy of the GCC Runtime Library Exception along with this program;     --

-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --

-- <http://www.gnu.org/licenses/>.                                          --

--                                                                          --

-- GNARL was developed by the GNARL team at Florida State University.       --

-- Extensive contributions were provided by Ada Core Technologies, Inc.     --

--                                                                          --

------------------------------------------------------------------------------

--  This is a OpenVMS/Alpha version of this package

--  This package contains all the GNULL primitives that interface directly with

--  the underlying OS.

pragma Polling (Off);

--  Turn off polling, we do not want ATC polling to take place during tasking

--  operations. It causes infinite loops and other problems.

with Ada.Unchecked_Conversion;

with Interfaces.C;

with System.Tasking.Debug;

with System.OS_Primitives;

with System.Soft_Links;

with System.Aux_DEC;

package body System.Task_Primitives.Operations is

   use System.Tasking.Debug;

   use System.Tasking;

   use Interfaces.C;

   use System.OS_Interface;

   use System.Parameters;

   use System.OS_Primitives;

   use type System.OS_Primitives.OS_Time;

   package SSL renames System.Soft_Links;

   ----------------

   -- Local Data --

   ----------------

   --  The followings are logically constants, but need to be initialized

   --  at run time.

   Single_RTS_Lock : aliased RTS_Lock;

   --  This is a lock to allow only one thread of control in the RTS at

   --  a time; it is used to execute in mutual exclusion from all other tasks.

   --  Used mainly in Single_Lock mode, but also to protect All_Tasks_List

   ATCB_Key : aliased pthread_key_t;

   --  Key used to find the Ada Task_Id associated with a thread

   Environment_Task_Id : Task_Id;

   --  A variable to hold Task_Id for the environment task

   Time_Slice_Val : Integer;

   pragma Import (C, Time_Slice_Val, "__gl_time_slice_val");

   Dispatching_Policy : Character;

   pragma Import (C, Dispatching_Policy, "__gl_task_dispatching_policy");

   Foreign_Task_Elaborated : aliased Boolean := True;

   --  Used to identified fake tasks (i.e., non-Ada Threads)

   --------------------

   -- Local Packages --

   --------------------

   package Specific is

      procedure Initialize (Environment_Task : Task_Id);

      pragma Inline (Initialize);

      --  Initialize various data needed by this package

      function Is_Valid_Task return Boolean;

      pragma Inline (Is_Valid_Task);

      --  Does executing thread have a TCB?

      procedure Set (Self_Id : Task_Id);

      pragma Inline (Set);

      --  Set the self id for the current task

      function Self return Task_Id;

      pragma Inline (Self);

      --  Return a pointer to the Ada Task Control Block of the calling task

   end Specific;

   package body Specific is separate;

   --  The body of this package is target specific

   ----------------------------------

   -- ATCB allocation/deallocation --

   ----------------------------------

   package body ATCB_Allocation is separate;

   --  The body of this package is shared across several targets

   ---------------------------------

   -- Support for foreign threads --

   ---------------------------------

   function Register_Foreign_Thread (Thread : Thread_Id) return Task_Id;

   --  Allocate and Initialize a new ATCB for the current Thread

   function Register_Foreign_Thread

     (Thread : Thread_Id) return Task_Id is separate;

   -----------------------

   -- Local Subprograms --

   -----------------------

   function To_Task_Id is

     new Ada.Unchecked_Conversion

       (System.Task_Primitives.Task_Address, Task_Id);

   function To_Address is

     new Ada.Unchecked_Conversion

       (Task_Id, System.Task_Primitives.Task_Address);

   procedure Timer_Sleep_AST (ID : Address);

   pragma Convention (C, Timer_Sleep_AST);

   --  Signal the condition variable when AST fires

   procedure Timer_Sleep_AST (ID : Address) is

      Result : Interfaces.C.int;

      pragma Warnings (Off, Result);

      Self_ID : constant Task_Id := To_Task_Id (ID);

   begin

      Self_ID.Common.LL.AST_Pending := False;

      Result := pthread_cond_signal_int_np (Self_ID.Common.LL.CV'Access);

      pragma Assert (Result = 0);

   end Timer_Sleep_AST;

   -----------------

   -- Stack_Guard --

   -----------------

   --  The underlying thread system sets a guard page at the bottom of a thread

   --  stack, so nothing is needed.

   --  ??? Check the comment above

   procedure Stack_Guard (T : ST.Task_Id; On : Boolean) is

      pragma Unreferenced (T);

      pragma Unreferenced (On);

   begin

      null;

   end Stack_Guard;

   --------------------

   -- Get_Thread_Id  --

   --------------------

   function Get_Thread_Id (T : ST.Task_Id) return OSI.Thread_Id is

   begin

      return T.Common.LL.Thread;

   end Get_Thread_Id;

   ----------

   -- Self --

   ----------

   function Self return Task_Id renames Specific.Self;

   ---------------------

   -- Initialize_Lock --

   ---------------------

   --  Note: mutexes and cond_variables needed per-task basis are initialized

   --  in Initialize_TCB and the Storage_Error is handled. Other mutexes (such

   --  as RTS_Lock, Memory_Lock...) used in RTS is initialized before any

   --  status change of RTS. Therefore raising Storage_Error in the following

   --  routines should be able to be handled safely.

   procedure Initialize_Lock

     (Prio : System.Any_Priority;

      L    : not null access Lock)

   is

      Attributes : aliased pthread_mutexattr_t;

      Result     : Interfaces.C.int;

   begin

      Result := pthread_mutexattr_init (Attributes'Access);

      pragma Assert (Result = 0 or else Result = ENOMEM);

      if Result = ENOMEM then

         raise Storage_Error;

      end if;

      L.Prio_Save := 0;

      L.Prio := Interfaces.C.int (Prio);

      Result := pthread_mutex_init (L.L'Access, Attributes'Access);

      pragma Assert (Result = 0 or else Result = ENOMEM);

      if Result = ENOMEM then

         raise Storage_Error;

      end if;

      Result := pthread_mutexattr_destroy (Attributes'Access);

      pragma Assert (Result = 0);

   end Initialize_Lock;

   procedure Initialize_Lock

     (L     : not null access RTS_Lock;

      Level : Lock_Level)

   is

      pragma Unreferenced (Level);

      Attributes : aliased pthread_mutexattr_t;

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutexattr_init (Attributes'Access);

      pragma Assert (Result = 0 or else Result = ENOMEM);

      if Result = ENOMEM then

         raise Storage_Error;

      end if;

--      Don't use, see comment in s-osinte.ads about ERRORCHECK mutexes???

--      Result := pthread_mutexattr_settype_np

--        (Attributes'Access, PTHREAD_MUTEX_ERRORCHECK_NP);

--      pragma Assert (Result = 0);

--      Result := pthread_mutexattr_setprotocol

--        (Attributes'Access, PTHREAD_PRIO_PROTECT);

--      pragma Assert (Result = 0);

--      Result := pthread_mutexattr_setprioceiling

--         (Attributes'Access, Interfaces.C.int (System.Any_Priority'Last));

--      pragma Assert (Result = 0);

      Result := pthread_mutex_init (L, Attributes'Access);

      pragma Assert (Result = 0 or else Result = ENOMEM);

      if Result = ENOMEM then

         raise Storage_Error;

      end if;

      Result := pthread_mutexattr_destroy (Attributes'Access);

      pragma Assert (Result = 0);

   end Initialize_Lock;

   -------------------

   -- Finalize_Lock --

   -------------------

   procedure Finalize_Lock (L : not null access Lock) is

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutex_destroy (L.L'Access);

      pragma Assert (Result = 0);

   end Finalize_Lock;

   procedure Finalize_Lock (L : not null access RTS_Lock) is

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutex_destroy (L);

      pragma Assert (Result = 0);

   end Finalize_Lock;

   ----------------

   -- Write_Lock --

   ----------------

   procedure Write_Lock

     (L                 : not null access Lock;

      Ceiling_Violation : out Boolean)

   is

      Self_ID        : constant Task_Id := Self;

      All_Tasks_Link : constant Task_Id := Self.Common.All_Tasks_Link;

      Current_Prio   : System.Any_Priority;

      Result         : Interfaces.C.int;

   begin

      Current_Prio := Get_Priority (Self_ID);

      --  If there is no other tasks, no need to check priorities

      if All_Tasks_Link /= Null_Task

        and then L.Prio < Interfaces.C.int (Current_Prio)

      then

         Ceiling_Violation := True;

         return;

      end if;

      Result := pthread_mutex_lock (L.L'Access);

      pragma Assert (Result = 0);

      Ceiling_Violation := False;

--  Why is this commented out ???

--      L.Prio_Save := Interfaces.C.int (Current_Prio);

--      Set_Priority (Self_ID, System.Any_Priority (L.Prio));

   end Write_Lock;

   procedure Write_Lock

     (L           : not null access RTS_Lock;

      Global_Lock : Boolean := False)

   is

      Result : Interfaces.C.int;

   begin

      if not Single_Lock or else Global_Lock then

         Result := pthread_mutex_lock (L);

         pragma Assert (Result = 0);

      end if;

   end Write_Lock;

   procedure Write_Lock (T : Task_Id) is

      Result : Interfaces.C.int;

   begin

      if not Single_Lock then

         Result := pthread_mutex_lock (T.Common.LL.L'Access);

         pragma Assert (Result = 0);

      end if;

   end Write_Lock;

   ---------------

   -- Read_Lock --

   ---------------

   procedure Read_Lock

     (L                 : not null access Lock;

      Ceiling_Violation : out Boolean)

   is

   begin

      Write_Lock (L, Ceiling_Violation);

   end Read_Lock;

   ------------

   -- Unlock --

   ------------

   procedure Unlock (L : not null access Lock) is

      Result : Interfaces.C.int;

   begin

      Result := pthread_mutex_unlock (L.L'Access);

      pragma Assert (Result = 0);

   end Unlock;

   procedure Unlock

     (L           : not null access RTS_Lock;

      Global_Lock : Boolean := False)

   is

      Result : Interfaces.C.int;

   begin

      if not Single_Lock or else Global_Lock then

         Result := pthread_mutex_unlock (L);

         pragma Assert (Result = 0);

      end if;

   end Unlock;

   procedure Unlock (T : Task_Id) is

      Result : Interfaces.C.int;

   begin

      if not Single_Lock then

         Result := pthread_mutex_unlock (T.Common.LL.L'Access);

         pragma Assert (Result = 0);

      end if;

   end Unlock;

   -----------------

   -- Set_Ceiling --

   -----------------

   --  Dynamic priority ceilings are not supported by the underlying system

   procedure Set_Ceiling

     (L    : not null access Lock;

      Prio : System.Any_Priority)

   is

      pragma Unreferenced (L, Prio);

   begin

      null;

   end Set_Ceiling;

   -----------

   -- Sleep --

   -----------

   procedure Sleep

     (Self_ID : Task_Id;

      Reason  : System.Tasking.Task_States)

   is

      pragma Unreferenced (Reason);

      Result : Interfaces.C.int;

   begin

      Result :=

        pthread_cond_wait

          (cond  => Self_ID.Common.LL.CV'Access,

           mutex => (if Single_Lock

                     then Single_RTS_Lock'Access

                     else Self_ID.Common.LL.L'Access));

      --  EINTR is not considered a failure

      pragma Assert (Result = 0 or else Result = EINTR);

      if Self_ID.Deferral_Level = 0

        and then Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level

      then

         Unlock (Self_ID);

         raise Standard'Abort_Signal;

      end if;

   end Sleep;

   -----------------

   -- Timed_Sleep --

   -----------------

   procedure Timed_Sleep

     (Self_ID  : Task_Id;

      Time     : Duration;

      Mode     : ST.Delay_Modes;

      Reason   : System.Tasking.Task_States;

      Timedout : out Boolean;

      Yielded  : out Boolean)

   is

      pragma Unreferenced (Reason);

      Sleep_Time : OS_Time;

      Result     : Interfaces.C.int;

      Status     : Cond_Value_Type;

      --  The body below requires more comments ???

   begin

      Timedout := False;

      Yielded := False;

      Sleep_Time := To_OS_Time (Time, Mode);

      if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level then

         return;

      end if;

      Self_ID.Common.LL.AST_Pending := True;

      Sys_Setimr

       (Status, 0, Sleep_Time,

        Timer_Sleep_AST'Access, To_Address (Self_ID), 0);

      if (Status and 1) /= 1 then

         raise Storage_Error;

      end if;

      if Single_Lock then

         Result :=

           pthread_cond_wait

             (Self_ID.Common.LL.CV'Access, Single_RTS_Lock'Access);

         pragma Assert (Result = 0);

      else

         Result :=

           pthread_cond_wait

             (Self_ID.Common.LL.CV'Access, Self_ID.Common.LL.L'Access);

         pragma Assert (Result = 0);

      end if;

      Yielded := True;

      if not Self_ID.Common.LL.AST_Pending then

         Timedout := True;

      else

         Sys_Cantim (Status, To_Address (Self_ID), 0);

         pragma Assert ((Status and 1) = 1);

      end if;

   end Timed_Sleep;

   -----------------

   -- Timed_Delay --

   -----------------

   procedure Timed_Delay

     (Self_ID : Task_Id;

      Time    : Duration;

      Mode    : ST.Delay_Modes)

   is

      Sleep_Time : OS_Time;

      Result     : Interfaces.C.int;

      Status     : Cond_Value_Type;

      Yielded    : Boolean := False;

   begin

      if Single_Lock then

         Lock_RTS;

      end if;

      --  More comments required in body below ???

      Write_Lock (Self_ID);

      if Time /= 0.0 or else Mode /= Relative then

         Sleep_Time := To_OS_Time (Time, Mode);

         if Mode = Relative or else OS_Clock <= Sleep_Time then

            Self_ID.Common.State := Delay_Sleep;

            Self_ID.Common.LL.AST_Pending := True;

            Sys_Setimr

             (Status, 0, Sleep_Time,

              Timer_Sleep_AST'Access, To_Address (Self_ID), 0);

            --  Comment following test

            if (Status and 1) /= 1 then

               raise Storage_Error;

            end if;

            loop

               if Self_ID.Pending_ATC_Level < Self_ID.ATC_Nesting_Level then

                  Sys_Cantim (Status, To_Address (Self_ID), 0);

                  pragma Assert ((Status and 1) = 1);

                  exit;

               end if;

               Result :=

                 pthread_cond_wait

                   (cond  => Self_ID.Common.LL.CV'Access,

                    mutex => (if Single_Lock

                              then Single_RTS_Lock'Access

                              else Self_ID.Common.LL.L'Access));

               pragma Assert (Result = 0);

               Yielded := True;

               exit when not Self_ID.Common.LL.AST_Pending;

            end loop;

            Self_ID.Common.State := Runnable;

         end if;

      end if;

      Unlock (Self_ID);

      if Single_Lock then

         Unlock_RTS;

      end if;

      if not Yielded then

         Result := sched_yield;

         pragma Assert (Result = 0);

      end if;

   end Timed_Delay;

   ---------------------

   -- Monotonic_Clock --

   ---------------------

   function Monotonic_Clock return Duration

     renames System.OS_Primitives.Monotonic_Clock;

   -------------------

   -- RT_Resolution --

   -------------------

   function RT_Resolution return Duration is

   begin

      --  Document origin of this magic constant ???

      return 10#1.0#E-3;

   end RT_Resolution;

   ------------

   -- Wakeup --

   ------------

   procedure Wakeup (T : Task_Id; Reason : System.Tasking.Task_States) is

      pragma Unreferenced (Reason);

      Result : Interfaces.C.int;

   begin

      Result := pthread_cond_signal (T.Common.LL.CV'Access);

      pragma Assert (Result = 0);

   end Wakeup;

   -----------

   -- Yield --

   -----------

   procedure Yield (Do_Yield : Boolean := True) is

      Result : Interfaces.C.int;

      pragma Unreferenced (Result);

   begin

      if Do_Yield then

         Result := sched_yield;

      end if;

   end Yield;

   ------------------

   -- Set_Priority --

   ------------------

   procedure Set_Priority

     (T                   : Task_Id;

      Prio                : System.Any_Priority;

      Loss_Of_Inheritance : Boolean := False)

   is

      pragma Unreferenced (Loss_Of_Inheritance);

      Result : Interfaces.C.int;

      Param  : aliased struct_sched_param;

      function Get_Policy (Prio : System.Any_Priority) return Character;

      pragma Import (C, Get_Policy, "__gnat_get_specific_dispatching");

      --  Get priority specific dispatching policy

      Priority_Specific_Policy : constant Character := Get_Policy (Prio);

      --  Upper case first character of the policy name corresponding to the

      --  task as set by a Priority_Specific_Dispatching pragma.

   begin

      T.Common.Current_Priority := Prio;

      Param.sched_priority := Interfaces.C.int (Underlying_Priorities (Prio));

      if Dispatching_Policy = 'R'

        or else Priority_Specific_Policy = 'R'

        or else Time_Slice_Val > 0

      then

         Result :=

           pthread_setschedparam

             (T.Common.LL.Thread, SCHED_RR, Param'Access);

      elsif Dispatching_Policy = 'F'

        or else Priority_Specific_Policy = 'F'

        or else Time_Slice_Val = 0

      then

         Result :=

           pthread_setschedparam

             (T.Common.LL.Thread, SCHED_FIFO, Param'Access);

      else

         --  SCHED_OTHER priorities are restricted to the range 8 - 15.

         --  Since the translation from Underlying priorities results

         --  in a range of 16 - 31, dividing by 2 gives the correct result.

         Param.sched_priority := Param.sched_priority / 2;

         Result :=

           pthread_setschedparam

             (T.Common.LL.Thread, SCHED_OTHER, Param'Access);

      end if;

      pragma Assert (Result = 0);

   end Set_Priority;

   ------------------

   -- Get_Priority --

   ------------------

   function Get_Priority (T : Task_Id) return System.Any_Priority is

   begin

      return T.Common.Current_Priority;

   end Get_Priority;

   ----------------

   -- Enter_Task --

   ----------------

   procedure Enter_Task (Self_ID : Task_Id) is

   begin

      Self_ID.Common.LL.Thread := pthread_self;

      Specific.Set (Self_ID);

   end Enter_Task;

   -------------------

   -- Is_Valid_Task --

   -------------------

   function Is_Valid_Task return Boolean renames Specific.Is_Valid_Task;

   -----------------------------

   -- Register_Foreign_Thread --

   -----------------------------

   function Register_Foreign_Thread return Task_Id is

   begin

      if Is_Valid_Task then

         return Self;

      else

         return Register_Foreign_Thread (pthread_self);

      end if;

   end Register_Foreign_Thread;

   --------------------

   -- Initialize_TCB --

   --------------------

   procedure Initialize_TCB (Self_ID : Task_Id; Succeeded : out Boolean) is

      Mutex_Attr : aliased pthread_mutexattr_t;

      Result     : Interfaces.C.int;

      Cond_Attr  : aliased pthread_condattr_t;

   begin

      --  More comments required in body below ???

      if not Single_Lock then

         Result := pthread_mutexattr_init (Mutex_Attr'Access);

         pragma Assert (Result = 0 or else Result = ENOMEM);

         if Result = 0 then

            Result :=

              pthread_mutex_init

                (Self_ID.Common.LL.L'Access, Mutex_Attr'Access);

            pragma Assert (Result = 0 or else Result = ENOMEM);

         end if;

         if Result /= 0 then

            Succeeded := False;

            return;

         end if;

         Result := pthread_mutexattr_destroy (Mutex_Attr'Access);

         pragma Assert (Result = 0);

      end if;

      Result := pthread_condattr_init (Cond_Attr'Access);

      pragma Assert (Result = 0 or else Result = ENOMEM);

      if Result = 0 then

         Result :=

           pthread_cond_init

             (Self_ID.Common.LL.CV'Access, Cond_Attr'Access);

         pragma Assert (Result = 0 or else Result = ENOMEM);

      end if;

      if Result = 0 then

         Succeeded := True;

      else

         if not Single_Lock then

            Result := pthread_mutex_destroy (Self_ID.Common.LL.L'Access);

            pragma Assert (Result = 0);

         end if;

         Succeeded := False;

      end if;

      Result := pthread_condattr_destroy (Cond_Attr'Access);

      pragma Assert (Result = 0);

   end Initialize_TCB;

   -----------------