[jira] Commented: (STDCXX-792) __rw_locale::_C_manage() uses mutex based __rw_atomic_preincrement() even if platform supports the native atomic operations

["Farid Zaripov (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/STDCXX-792?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12581591#action_12581591 ] 

Farid Zaripov commented on STDCXX-792:
--------------------------------------

The proposed patch below:

  ChangeLog:
  STDCXX-792
  * src/locale_body.cpp (_C_manage): Declare static variable ginit as non-volatile, to use the
  non-template version __rw_atomic_preincrement() instead of template version, if available.
  Declare static variable ginit as int instead of long because the all native atomic  functions
  are defined for int type and the overloads for long type just calls overload for int type on
  platforms where sizeof (int) == sizeof (long).

{noformat}
Index: src/locale_body.cpp
===================================================================
--- src/locale_body.cpp	(revision 640425)
+++ src/locale_body.cpp	(working copy)
@@ -805,7 +805,7 @@
 
         if (!global) {
 
-            static volatile long ginit /* = 0 */;
+            static int ginit /* = 0 */;
 
             if (!ginit && 1 == _RWSTD_ATOMIC_PREINCREMENT (ginit, false)) {
                 global  = _C_manage (0, "C");
{noformat}


> __rw_locale::_C_manage() uses mutex based __rw_atomic_preincrement() even if platform supports the native atomic operations
> ---------------------------------------------------------------------------------------------------------------------------
>
>                 Key: STDCXX-792
>                 URL: https://issues.apache.org/jira/browse/STDCXX-792
>             Project: C++ Standard Library
>          Issue Type: Bug
>          Components: 22. Localization
>    Affects Versions: 4.1.2, 4.1.3, 4.1.4, 4.2.0
>         Environment: All
>            Reporter: Farid Zaripov
>            Assignee: Farid Zaripov
>             Fix For: 4.2.1
>
>   Original Estimate: 0.5h
>  Remaining Estimate: 0.5h
>
> In __rw_locale::_C_manage() (src/locale_body.cpp, line 808), the static variable ginit declared as volatile, but __rw_atomic_preincrement() functions, which are implemented using atomic operations, accepting the non-volatile reference in parameter list. As a result the template version __rw_atomic_preincrement<volatile long>() (which is implemented using mutex object) is used.

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