------------------------------------------------------------------------------
-- --
--- GNU ADA RUN-TIME LIBRARY (GNARL) COMPONENTS --
+-- GNAT RUN-TIME LIBRARY (GNARL) COMPONENTS --
-- --
--- SYSTEM.TASKING.PROTECTED_OBJECTS.ENTRIES --
+-- SYSTEM.TASKING.PROTECTED_OBJECTS.ENTRIES --
-- --
--- B o d y --
+-- B o d y --
-- --
--- Copyright (C) 1998-2001, Free Software Foundation, Inc. --
+-- Copyright (C) 1998-2010, 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 2, or (at your option) any later ver- --
--- sion. GNARL is distributed in the hope that it will be useful, but WITH- --
+-- 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. See the GNU General Public License --
--- for more details. You should have received a copy of the GNU General --
--- Public License distributed with GNARL; see file COPYING. If not, write --
--- to the Free Software Foundation, 59 Temple Place - Suite 330, Boston, --
--- MA 02111-1307, USA. --
+-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
--- As a special exception, if other files instantiate generics from this --
--- unit, or you link this unit with other files to produce an executable, --
--- this unit does not by itself cause the resulting executable to be --
--- covered by the GNU General Public License. This exception does not --
--- however invalidate any other reasons why the executable file might be --
--- covered by the GNU Public License. --
+-- 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. --
-- --
--- GNARL was developed by the GNARL team at Florida State University. It is --
--- now maintained by Ada Core Technologies, Inc. (http://www.gnat.com). --
+-- 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 package contains all the simple primitives related to
--- Protected_Objects with entries (i.e init, lock, unlock).
+-- This package contains all the simple primitives related to protected
+-- objects with entries (i.e init, lock, unlock).
-- The handling of protected objects with no entries is done in
-- System.Tasking.Protected_Objects, the complex routines for protected
-- objects with entries in System.Tasking.Protected_Objects.Operations.
+
-- The split between Entries and Operations is needed to break circular
-- dependencies inside the run time.
--- Note: the compiler generates direct calls to this interface, via Rtsfind.
+-- Note: the compiler generates direct calls to this interface, via Rtsfind
-with Ada.Exceptions;
--- used for Exception_Occurrence_Access
+with Ada.Unchecked_Deallocation;
with System.Task_Primitives.Operations;
--- used for Initialize_Lock
--- Write_Lock
--- Unlock
--- Get_Priority
--- Wakeup
+with System.Restrictions;
+with System.Parameters;
with System.Tasking.Initialization;
--- used for Defer_Abort,
--- Undefer_Abort,
--- Change_Base_Priority
-
pragma Elaborate_All (System.Tasking.Initialization);
--- this insures that tasking is initialized if any protected objects are
--- created.
-
-with System.Parameters;
--- used for Single_Lock
+-- To insure that tasking is initialized if any protected objects are created
package body System.Tasking.Protected_Objects.Entries is
use Parameters;
use Task_Primitives.Operations;
- use Ada.Exceptions;
+
+ -----------------------
+ -- Local Subprograms --
+ -----------------------
+
+ procedure Free_Entry_Names (Object : Protection_Entries);
+ -- Deallocate all string names associated with protected entries
+
+ ----------------
+ -- Local Data --
+ ----------------
Locking_Policy : Character;
pragma Import (C, Locking_Policy, "__gl_locking_policy");
-- Finalize --
--------------
- procedure Finalize (Object : in out Protection_Entries) is
+ overriding procedure Finalize (Object : in out Protection_Entries) is
Entry_Call : Entry_Call_Link;
- Caller : Task_ID;
+ Caller : Task_Id;
Ceiling_Violation : Boolean;
- Self_ID : constant Task_ID := STPO.Self;
+ Self_ID : constant Task_Id := STPO.Self;
Old_Base_Priority : System.Any_Priority;
begin
end if;
if Ceiling_Violation then
- -- Dip our own priority down to ceiling of lock.
- -- See similar code in Tasking.Entry_Calls.Lock_Server.
+
+ -- Dip our own priority down to ceiling of lock. See similar code in
+ -- Tasking.Entry_Calls.Lock_Server.
STPO.Write_Lock (Self_ID);
Old_Base_Priority := Self_ID.Common.Base_Priority;
STPO.Write_Lock (Object.L'Unrestricted_Access, Ceiling_Violation);
if Ceiling_Violation then
- Raise_Exception (Program_Error'Identity, "Ceiling Violation");
+ raise Program_Error with "Ceiling Violation";
end if;
if Single_Lock then
Object.Pending_Action := True;
end if;
- -- Send program_error to all tasks still queued on this object.
+ -- Send program_error to all tasks still queued on this object
for E in Object.Entry_Queues'Range loop
Entry_Call := Object.Entry_Queues (E).Head;
end loop;
end loop;
+ Free_Entry_Names (Object);
+
Object.Finalized := True;
if Single_Lock then
STPO.Finalize_Lock (Object.L'Unrestricted_Access);
end Finalize;
+ ----------------------
+ -- Free_Entry_Names --
+ ----------------------
+
+ procedure Free_Entry_Names (Object : Protection_Entries) is
+ Names : Entry_Names_Array_Access := Object.Entry_Names;
+
+ procedure Free_Entry_Names_Array_Access is new
+ Ada.Unchecked_Deallocation
+ (Entry_Names_Array, Entry_Names_Array_Access);
+
+ begin
+ if Names = null then
+ return;
+ end if;
+
+ Free_Entry_Names_Array (Names.all);
+ Free_Entry_Names_Array_Access (Names);
+ end Free_Entry_Names;
+
+ -----------------
+ -- Get_Ceiling --
+ -----------------
+
+ function Get_Ceiling
+ (Object : Protection_Entries_Access) return System.Any_Priority is
+ begin
+ return Object.New_Ceiling;
+ end Get_Ceiling;
+
-------------------------------------
-- Has_Interrupt_Or_Attach_Handler --
-------------------------------------
Ceiling_Priority : Integer;
Compiler_Info : System.Address;
Entry_Bodies : Protected_Entry_Body_Access;
- Find_Body_Index : Find_Body_Index_Access)
+ Find_Body_Index : Find_Body_Index_Access;
+ Build_Entry_Names : Boolean)
is
Init_Priority : Integer := Ceiling_Priority;
- Self_ID : constant Task_ID := STPO.Self;
+ Self_ID : constant Task_Id := STPO.Self;
begin
if Init_Priority = Unspecified_Priority then
- Init_Priority := System.Priority'Last;
+ Init_Priority := System.Priority'Last;
end if;
if Locking_Policy = 'C'
raise Program_Error;
end if;
- Initialization.Defer_Abort (Self_ID);
+ -- pragma Assert (Self_Id.Deferral_Level = 0);
+ -- If a PO is created from a controlled operation, abort is already
+ -- deferred at this point, so we need to use Defer_Abort_Nestable
+ -- In some cases, the above assertion can be useful to spot
+ -- inconsistencies, outside the above scenario involving controlled
+ -- types.
+
+ Initialization.Defer_Abort_Nestable (Self_ID);
Initialize_Lock (Init_Priority, Object.L'Access);
- Initialization.Undefer_Abort (Self_ID);
- Object.Ceiling := System.Any_Priority (Init_Priority);
- Object.Compiler_Info := Compiler_Info;
- Object.Pending_Action := False;
+ Initialization.Undefer_Abort_Nestable (Self_ID);
+
+ Object.Ceiling := System.Any_Priority (Init_Priority);
+ Object.New_Ceiling := System.Any_Priority (Init_Priority);
+ Object.Owner := Null_Task;
+ Object.Compiler_Info := Compiler_Info;
+ Object.Pending_Action := False;
Object.Call_In_Progress := null;
- Object.Entry_Bodies := Entry_Bodies;
- Object.Find_Body_Index := Find_Body_Index;
+ Object.Entry_Bodies := Entry_Bodies;
+ Object.Find_Body_Index := Find_Body_Index;
for E in Object.Entry_Queues'Range loop
Object.Entry_Queues (E).Head := null;
Object.Entry_Queues (E).Tail := null;
end loop;
+
+ if Build_Entry_Names then
+ Object.Entry_Names :=
+ new Entry_Names_Array (1 .. Entry_Index (Object.Num_Entries));
+ end if;
end Initialize_Protection_Entries;
------------------
------------------
procedure Lock_Entries
- (Object : Protection_Entries_Access; Ceiling_Violation : out Boolean) is
+ (Object : Protection_Entries_Access;
+ Ceiling_Violation : out Boolean)
+ is
begin
if Object.Finalized then
- Raise_Exception
- (Program_Error'Identity, "Protected Object is finalized");
+ raise Program_Error with "Protected Object is finalized";
+ end if;
+
+ -- 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;
- -- The lock is made without defering abortion.
+ -- The lock is made without deferring abort
- -- Therefore the abortion 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.
+ -- 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 abortion, and compiler
+ -- The caller is responsible for undeferring abort, and compiler
-- generated calls must be protected with cleanup handlers to ensure
- -- that abortion is undeferred in all cases.
+ -- that abort is undeferred in all cases.
+
+ pragma Assert
+ (STPO.Self.Deferral_Level > 0
+ or else not Restrictions.Abort_Allowed);
- pragma Assert (STPO.Self.Deferral_Level > 0);
Write_Lock (Object.L'Access, Ceiling_Violation);
+
+ -- 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_Entries;
procedure Lock_Entries (Object : Protection_Entries_Access) is
Ceiling_Violation : Boolean;
- begin
- if Object.Finalized then
- Raise_Exception
- (Program_Error'Identity, "Protected Object is finalized");
- end if;
- pragma Assert (STPO.Self.Deferral_Level > 0);
- Write_Lock (Object.L'Access, Ceiling_Violation);
+ begin
+ Lock_Entries (Object, Ceiling_Violation);
if Ceiling_Violation then
- Raise_Exception (Program_Error'Identity, "Ceiling Violation");
+ raise Program_Error with "Ceiling Violation";
end if;
end Lock_Entries;
procedure Lock_Read_Only_Entries (Object : Protection_Entries_Access) is
Ceiling_Violation : Boolean;
+
begin
if Object.Finalized then
- Raise_Exception
- (Program_Error'Identity, "Protected Object is finalized");
+ raise Program_Error with "Protected Object is finalized";
+ end if;
+
+ -- 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.
+
+ -- 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 Ceiling_Violation then
- Raise_Exception (Program_Error'Identity, "Ceiling Violation");
+ raise Program_Error with "Ceiling Violation";
+ 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_Read_Only_Entries;
+ -----------------
+ -- Set_Ceiling --
+ -----------------
+
+ procedure Set_Ceiling
+ (Object : Protection_Entries_Access;
+ Prio : System.Any_Priority) is
+ begin
+ Object.New_Ceiling := Prio;
+ end Set_Ceiling;
+
+ --------------------
+ -- Set_Entry_Name --
+ --------------------
+
+ procedure Set_Entry_Name
+ (Object : Protection_Entries'Class;
+ Pos : Protected_Entry_Index;
+ Val : String_Access)
+ is
+ begin
+ pragma Assert (Object.Entry_Names /= null);
+
+ Object.Entry_Names (Entry_Index (Pos)) := Val;
+ end Set_Entry_Name;
+
--------------------
-- Unlock_Entries --
--------------------
procedure Unlock_Entries (Object : Protection_Entries_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;
+
+ 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);
end Unlock_Entries;
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