[Ace-users] [ace-bugs] UUID_Generator

[Wim van den Boogaard]

ACE VERSION: 5.5.8 / 10

HOST MACHINE and OPERATING SYSTEM:
   WinXP

TARGET MACHINE and OPERATING SYSTEM, if different from HOST:
COMPILER NAME AND VERSION (AND PATCHLEVEL):

THE $ACE_ROOT/ace/config.h FILE [if you use a link to a platform-
   specific file, simply state which one]:
   config-win32.h


THE $ACE_ROOT/include/makeinclude/platform_macros.GNU FILE [if you
   use a link to a platform-specific file, simply state which one
   (unless this isn't used in this case, e.g., with Microsoft Visual
   C++)]:

CONTENTS OF $ACE_ROOT/bin/MakeProjectCreator/config/default.features
   (used by MPC when you generate your own makefiles):
    ---

AREA/CLASS/EXAMPLE AFFECTED:

   DOES THE PROBLEM AFFECT:
       COMPILATION?
       LINKING
       EXECUTION
         
       OTHER (please specify)?

   SYNOPSIS:
       Double UUID generated in a multi threaded application.

   DESCRIPTION:
        The method UUID_Generator::generateUUID is not thread safe in 
respect to the combination uuid_state_.clockSequence
        and timestamp.
        The combination timestamp and clockSequence should be accessed 
in a thread safe manner. The method
        UUID_Generator::get_timestamp returns the timestamp thread safe, 
but also modifies the uuid_state_.clockSequence.
        The uuid_state_.clockSequence is accessed thread safe in 
UUID_Generator::generateUUID, but could have been modified
        between the moment get_timestamp is being done and the moment it 
is being used.

   REPEAT BY:

   SAMPLE FIX/WORKAROUND:
        Return the timestamp and clockSequence in a atomic manner via 
the get_timestamp method. I added an other argument
        to the get_timestamp.
        void get_timestamp(UUID_time& timestamp, ACE_UINT16& clockSequence);

        Return the actual clockSequence in the get_timestamp method.