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Diffstat (limited to 'gcc-4.9/gcc/ada/s-taprob.adb')
| -rw-r--r-- | gcc-4.9/gcc/ada/s-taprob.adb | 279 |
1 files changed, 279 insertions, 0 deletions
diff --git a/gcc-4.9/gcc/ada/s-taprob.adb b/gcc-4.9/gcc/ada/s-taprob.adb new file mode 100644 index 000000000..ab0557d86 --- /dev/null +++ b/gcc-4.9/gcc/ada/s-taprob.adb @@ -0,0 +1,279 @@ +------------------------------------------------------------------------------ +-- -- +-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS -- +-- -- +-- S Y S T E M . T A S K I N G . P R O T E C T E D _ O B J E C T S -- +-- -- +-- B o d y -- +-- -- +-- Copyright (C) 1991-1994, Florida State University -- +-- Copyright (C) 1995-2011, AdaCore -- +-- -- +-- GNAT 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. -- +-- -- +------------------------------------------------------------------------------ + +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 System.Task_Primitives.Operations; +with System.Parameters; +with System.Traces; +with System.Soft_Links.Tasking; + +package body System.Tasking.Protected_Objects is + + use System.Task_Primitives.Operations; + use System.Traces; + + ---------------- + -- Local Data -- + ---------------- + + Locking_Policy : Character; + pragma Import (C, Locking_Policy, "__gl_locking_policy"); + + ------------------------- + -- Finalize_Protection -- + ------------------------- + + procedure Finalize_Protection (Object : in out Protection) is + begin + Finalize_Lock (Object.L'Unrestricted_Access); + end Finalize_Protection; + + --------------------------- + -- Initialize_Protection -- + --------------------------- + + procedure Initialize_Protection + (Object : Protection_Access; + Ceiling_Priority : Integer) + is + Init_Priority : Integer := Ceiling_Priority; + + begin + if Init_Priority = Unspecified_Priority then + Init_Priority := System.Priority'Last; + end if; + + Initialize_Lock (Init_Priority, Object.L'Access); + Object.Ceiling := System.Any_Priority (Init_Priority); + Object.New_Ceiling := System.Any_Priority (Init_Priority); + Object.Owner := Null_Task; + end Initialize_Protection; + + ----------------- + -- Get_Ceiling -- + ----------------- + + function Get_Ceiling + (Object : Protection_Access) return System.Any_Priority is + begin + return Object.New_Ceiling; + end Get_Ceiling; + + ---------- + -- Lock -- + ---------- + + procedure Lock (Object : Protection_Access) is + Ceiling_Violation : Boolean; + + begin + -- The lock is made without deferring abort + + -- Therefore the abort has to be deferred before calling this routine. + -- This means that the compiler has to generate a Defer_Abort call + -- before the call to Lock. + + -- The caller is responsible for undeferring abort, and compiler + -- generated calls must be protected with cleanup handlers to ensure + -- that abort is undeferred in all cases. + + -- If pragma Detect_Blocking is active then, as described in the ARM + -- 9.5.1, par. 15, we must check whether this is an external call on a + -- protected subprogram with the same target object as that of the + -- protected action that is currently in progress (i.e., if the caller + -- is already the protected object's owner). If this is the case hence + -- Program_Error must be raised. + + if Detect_Blocking and then Object.Owner = Self then + raise Program_Error; + end if; + + Write_Lock (Object.L'Access, Ceiling_Violation); + + if Parameters.Runtime_Traces then + Send_Trace_Info (PO_Lock); + end if; + + if Ceiling_Violation then + raise Program_Error; + end if; + + -- We are entering in a protected action, so that we increase the + -- protected object nesting level (if pragma Detect_Blocking is + -- active), and update the protected object's owner. + + if Detect_Blocking then + declare + Self_Id : constant Task_Id := Self; + begin + -- Update the protected object's owner + + Object.Owner := Self_Id; + + -- Increase protected object nesting level + + Self_Id.Common.Protected_Action_Nesting := + Self_Id.Common.Protected_Action_Nesting + 1; + end; + end if; + end Lock; + + -------------------- + -- Lock_Read_Only -- + -------------------- + + procedure Lock_Read_Only (Object : Protection_Access) is + Ceiling_Violation : Boolean; + + begin + -- If pragma Detect_Blocking is active then, as described in the ARM + -- 9.5.1, par. 15, we must check whether this is an external call on + -- protected subprogram with the same target object as that of the + -- protected action that is currently in progress (i.e., if the caller + -- is already the protected object's owner). If this is the case hence + -- Program_Error must be raised. + -- + -- Note that in this case (getting read access), several tasks may have + -- read ownership of the protected object, so that this method of + -- storing the (single) protected object's owner does not work reliably + -- for read locks. However, this is the approach taken for two major + -- reasons: first, this function is not currently being used (it is + -- provided for possible future use), and second, it largely simplifies + -- the implementation. + + if Detect_Blocking and then Object.Owner = Self then + raise Program_Error; + end if; + + Read_Lock (Object.L'Access, Ceiling_Violation); + + if Parameters.Runtime_Traces then + Send_Trace_Info (PO_Lock); + end if; + + if Ceiling_Violation then + raise Program_Error; + end if; + + -- We are entering in a protected action, so we increase the protected + -- object nesting level (if pragma Detect_Blocking is active). + + if Detect_Blocking then + declare + Self_Id : constant Task_Id := Self; + begin + -- Update the protected object's owner + + Object.Owner := Self_Id; + + -- Increase protected object nesting level + + Self_Id.Common.Protected_Action_Nesting := + Self_Id.Common.Protected_Action_Nesting + 1; + end; + end if; + end Lock_Read_Only; + + ----------------- + -- Set_Ceiling -- + ----------------- + + procedure Set_Ceiling + (Object : Protection_Access; + Prio : System.Any_Priority) is + begin + Object.New_Ceiling := Prio; + end Set_Ceiling; + + ------------ + -- Unlock -- + ------------ + + procedure Unlock (Object : Protection_Access) is + begin + -- We are exiting from a protected action, so that we decrease the + -- protected object nesting level (if pragma Detect_Blocking is + -- active), and remove ownership of the protected object. + + if Detect_Blocking then + declare + Self_Id : constant Task_Id := Self; + + begin + -- Calls to this procedure can only take place when being within + -- a protected action and when the caller is the protected + -- object's owner. + + pragma Assert (Self_Id.Common.Protected_Action_Nesting > 0 + and then Object.Owner = Self_Id); + + -- Remove ownership of the protected object + + Object.Owner := Null_Task; + + -- We are exiting from a protected action, so we decrease the + -- protected object nesting level. + + Self_Id.Common.Protected_Action_Nesting := + Self_Id.Common.Protected_Action_Nesting - 1; + end; + end if; + + -- Before releasing the mutex we must actually update its ceiling + -- priority if it has been changed. + + if Object.New_Ceiling /= Object.Ceiling then + if Locking_Policy = 'C' then + System.Task_Primitives.Operations.Set_Ceiling + (Object.L'Access, Object.New_Ceiling); + end if; + + Object.Ceiling := Object.New_Ceiling; + end if; + + Unlock (Object.L'Access); + + if Parameters.Runtime_Traces then + Send_Trace_Info (PO_Unlock); + end if; + end Unlock; + +begin + -- Ensure that tasking is initialized, as well as tasking soft links + -- when using protected objects. + + Tasking.Initialize; + System.Soft_Links.Tasking.Init_Tasking_Soft_Links; +end System.Tasking.Protected_Objects; |