[ace-users] [ace-bugs] UUID_Generator

Wim van den Boogaard wim.van.den.boogaard at varianinc.com
Thu Sep 13 14:40:14 CDT 2007


Hello Doug,

I ran into an other problem when a lot UUIDs are generated quickly after 
each other, again duplicates are generated. This is being caused by the 
two occurences of the following line in UUID.cpp:
      uuid_state_.clockSequence = static_cast<u_char> 
((uuid_state_.clockSequence + 1) & ACE_UUID_CLOCK_SEQ_MASK);

This line should be:
      uuid_state_.clockSequence = static_cast<ACE_UINT16> 
((uuid_state_.clockSequence + 1) & ACE_UUID_CLOCK_SEQ_MASK);

Due to the casting to u_char instead of ACE_UINT16, duplicates are 
generated after more then 255.

Kind regards,

Wim van den Boogaard.

> Hi Wim,
>
>    ok, great, thanks for all the improvements and documentation.  I'll
> check this in after the x.6 release goes out tomorrow.  
>
>    BTW, Johnny, I've made a pass through UUID.{h,inl,cpp} and
> "ACE-ified" everything.  This may require some changes to user code,
> but the original API was totally inconsistent with ACE.
>
> Thanks,
>
>         Doug
>
>   
>> Thanks for the changes.
>>
>> This fix is working correctly for me.
>>
>> Changelog entry:
>> Implemented an accessor to obtain the timestamp and clockSequence in an 
>> atomic manner. The clockSequence could change between the moment the 
>> timestamp is obtained and the moment the clockSequence is used in a 
>> multithreaded environment and that results in duplicate UUIDs.
>>
>> Kind regards,
>>
>> Wim van den Boogaard.
>>     
>>> Hi Wim,
>>>
>>>   
>>>       
>>>> Hereby I sent you the source files, see attachments.
>>>>     
>>>>         
>>> Great, thanks!
>>>
>>>   
>>>       
>>>> Maybe it is better to rename the method get_timestamp to
>>>> get_timestampAndClocksequence.
>>>>     
>>>>         
>>> I've tweaked things a bit to ensure backwards compatibility with 
>>> existing applications.  Can you please check out
>>>
>>> http://www.dre.vanderbilt.edu/~schmidt/DOC_ROOT/ACE/ace/UUID.h
>>> http://www.dre.vanderbilt.edu/~schmidt/DOC_ROOT/ACE/ace/UUID.cpp
>>>
>>> and let me know if it's ok?  Also, could you please send me a brief
>>> ChangeLog entry explaining what you've done and why.
>>>
>>> Thanks very much,
>>>
>>>         Doug
>>>
>>>   
>>>       
>>>> Kind regards,
>>>>
>>>> Wim van den Boogaard
>>>>     
>>>>         
>>>>> Hi Wim,
>>>>>
>>>>> Thanks for using the PRF.
>>>>>
>>>>>
>>>>>       
>>>>>           
>>>>>> 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 $ACE_ROOT/bin/MakeProjectCreator/config/default.features
>>>>>>    (used by MPC when you generate your own makefiles):
>>>>>>     ---
>>>>>>
>>>>>> AREA/CLASS/EXAMPLE AFFECTED:
>>>>>>
>>>>>>    DOES THE PROBLEM AFFECT:
>>>>>>        COMPILATION?
>>>>>>        LINKING
>>>>>>        EXECUTION
>>>>>>                 OTHER (please specify)?
>>>>>>
>>>>>>    SYNOPSIS:
>>>>>>        Double UUID generated in a multi threaded application.
>>>>>>
>>>>>>    DESCRIPTION:
>>>>>>         The method UUID_Generator::generateUUID is not thread safe
>>>>>> in respect to the combination uuid_state_.clockSequence
>>>>>>         and timestamp.
>>>>>>         The combination timestamp and clockSequence should be
>>>>>> accessed in a thread safe manner. The method
>>>>>>         UUID_Generator::get_timestamp returns the timestamp thread
>>>>>> safe, but also modifies the uuid_state_.clockSequence.
>>>>>>         The uuid_state_.clockSequence is accessed thread safe in
>>>>>> UUID_Generator::generateUUID, but could have been modified
>>>>>>         between the moment get_timestamp is being done and the
>>>>>> moment it is being used.
>>>>>>
>>>>>>    REPEAT BY:
>>>>>>
>>>>>>    SAMPLE FIX/WORKAROUND:
>>>>>>         Return the timestamp and clockSequence in a atomic manner
>>>>>> via the get_timestamp method. I added an other argument
>>>>>>         to the get_timestamp.
>>>>>>         void get_timestamp(UUID_time& timestamp, ACE_UINT16& clockSequence);
>>>>>>
>>>>>>         Return the actual clockSequence in the get_timestamp method.
>>>>>>
>>>>>>         
>>>>>>             
>>>>> Could you please send the code that implements this and we'll add it to ACE!
>>>>>
>>>>> Thanks,
>>>>>
>>>>>         Doug
>>>>>
>>>>>
>>>>>       
>>>>>           
>>>> //$Id: UUID.cpp 78180 2007-04-25 07:05:02Z johnnyw $
>>>>
>>>> #include "ace/UUID.h"
>>>> #include "ace/Guard_T.h"
>>>>
>>>> #if !defined (__ACE_INLINE__)
>>>> #include "ace/UUID.inl"
>>>> #endif /* __ACE_INLINE__ */
>>>>
>>>> #include "ace/Log_Msg.h"
>>>> #include "ace/OS_NS_stdio.h"
>>>> #include "ace/OS_NS_string.h"
>>>> #include "ace/OS_NS_sys_time.h"
>>>> #include "ace/OS_NS_netdb.h"
>>>> #include "ace/OS_NS_unistd.h"
>>>> #include "ace/ACE.h"
>>>>
>>>> ACE_RCSID (ace,
>>>>            UUID,
>>>>            "$Id: UUID.cpp 78180 2007-04-25 07:05:02Z johnnyw $")
>>>>
>>>>
>>>> ACE_BEGIN_VERSIONED_NAMESPACE_DECL
>>>>
>>>> namespace ACE_Utils
>>>> {
>>>>
>>>>   UUID_node::UUID_node (void)
>>>>   {
>>>>     for (int i = 0; i < UUID_node::NODE_ID_SIZE; ++i)
>>>>       {
>>>>         nodeID_[i] = 0;
>>>>       }
>>>>   }
>>>>
>>>>   UUID_node::NodeID&
>>>>   UUID_node::nodeID (void)
>>>>   {
>>>>     return nodeID_;
>>>>   }
>>>>
>>>>   void
>>>>   UUID_node::nodeID (NodeID& nodeID)
>>>>   {
>>>>     for (int i = 0; i < UUID_node::NODE_ID_SIZE; ++i)
>>>>       {
>>>>         nodeID_[i] = nodeID[i];
>>>>       }
>>>>   }
>>>>
>>>>   UUID UUID::NIL_UUID;
>>>>
>>>>   /// Construct a nil UUID. Such a UUID has every one of it's data
>>>>   /// elements set to zero.
>>>>   UUID::UUID(void)
>>>>     : timeLow_ (0),
>>>>       timeMid_ (0),
>>>>       timeHiAndVersion_ (0),
>>>>       clockSeqHiAndReserved_ (0),
>>>>       clockSeqLow_ (0),
>>>>       node_ (0),
>>>>       node_release_ (true),
>>>>       as_string_ (0)
>>>>   {
>>>>     ACE_NEW (node_,
>>>>              UUID_node);
>>>>   }
>>>>
>>>>   /// Construct a UUID from a string representation of an UUID.
>>>>   UUID::UUID (const ACE_CString& uuid_string)
>>>>     : timeLow_ (0),
>>>>       timeMid_ (0),
>>>>       timeHiAndVersion_ (0),
>>>>       clockSeqHiAndReserved_ (0),
>>>>       clockSeqLow_ (0),
>>>>       node_ (0),
>>>>       node_release_ (true),
>>>>       as_string_ (0)
>>>>   {
>>>>     ACE_NEW (node_,
>>>>              UUID_node);
>>>>
>>>>     this->from_string_i (uuid_string);
>>>>   }
>>>>
>>>>   UUID::UUID(const UUID &right)
>>>>     : timeLow_ (right.timeLow_),
>>>>       timeMid_ (right.timeMid_),
>>>>       timeHiAndVersion_ (right.timeHiAndVersion_),
>>>>       clockSeqHiAndReserved_ (right.clockSeqHiAndReserved_),
>>>>       clockSeqLow_ (right.clockSeqLow_),
>>>>       as_string_ (0)
>>>>   {
>>>>     ACE_NEW (node_,
>>>>              UUID_node (*right.node_));
>>>>   }
>>>>
>>>>   UUID::~UUID (void)
>>>>   {
>>>>     if (node_release_)
>>>>       delete node_;
>>>>
>>>>     if (as_string_ != 0)
>>>>       delete as_string_;
>>>>   }
>>>>
>>>>   const ACE_CString*
>>>>   UUID::to_string (void)
>>>>   {
>>>>     /// Only compute the string representation once.
>>>>     if (as_string_ == 0)
>>>>       {
>>>>         // Get a buffer exactly the correct size. Use the nil UUID as a
>>>>         // gauge.  Don't forget the trailing nul.
>>>>         size_t UUID_STRING_LENGTH = 36 + thr_id_.length () + pid_.length ();
>>>>         char *buf = 0;
>>>>
>>>>         if ((thr_id_.length () != 0) && (pid_.length () != 0))
>>>>           {
>>>>             UUID_STRING_LENGTH += 2; //for '-'
>>>>             ACE_NEW_RETURN (buf,
>>>>                             char[UUID_STRING_LENGTH + 1],
>>>>                             0);
>>>>
>>>>             ACE_OS::sprintf(buf,
>>>>                             "%8.8x-%4.4x-%4.4x-%2.2x%2.2x-%2.2x%2.2x%2.2x%2.2x%2.2x%2.2x-%s-%s",
>>>>                             this->timeLow_,
>>>>                             this->timeMid_,
>>>>                             this->timeHiAndVersion_,
>>>>                             this->clockSeqHiAndReserved_,
>>>>                             this->clockSeqLow_,
>>>>                             (this->node_->nodeID ()) [0],
>>>>                             (this->node_->nodeID ()) [1],
>>>>                             (this->node_->nodeID ()) [2],
>>>>                             (this->node_->nodeID ()) [3],
>>>>                             (this->node_->nodeID ()) [4],
>>>>                             (this->node_->nodeID ()) [5],
>>>>                             thr_id_.c_str (),
>>>>                             pid_.c_str ()
>>>>                             );
>>>>           }
>>>>         else
>>>>           {
>>>>             ACE_NEW_RETURN (buf,
>>>>                             char[UUID_STRING_LENGTH + 1],
>>>>                             0);
>>>>
>>>>             ACE_OS::sprintf (buf,
>>>>                              "%8.8x-%4.4x-%4.4x-%2.2x%2.2x-%2.2x%2.2x%2.2x%2.2x%2.2x%2.2x",
>>>>                              this->timeLow_,
>>>>                              this->timeMid_,
>>>>                              this->timeHiAndVersion_,
>>>>                              this->clockSeqHiAndReserved_,
>>>>                              this->clockSeqLow_,
>>>>                              (this->node_->nodeID ()) [0],
>>>>                              (this->node_->nodeID ()) [1],
>>>>                              (this->node_->nodeID ()) [2],
>>>>                              (this->node_->nodeID ()) [3],
>>>>                              (this->node_->nodeID ()) [4],
>>>>                              (this->node_->nodeID ()) [5]
>>>>                              );
>>>>           }
>>>>
>>>>         // We allocated 'buf' above dynamically, so we shouldn't use
>>>>         // ACE_NEW_RETURN here to avoid a possible memory leak.
>>>>         ACE_NEW_NORETURN (this->as_string_,
>>>>                           ACE_CString (buf, UUID_STRING_LENGTH));
>>>>
>>>>         // we first free the dynamically allocated 'buf'.
>>>>         delete [] buf;
>>>>
>>>>         // then we test that ACE_NEW succeded for 'as_string_'
>>>>         // if not, we return 0 (NULL) to indicate failure.
>>>>         if( this->as_string_ == 0 )
>>>>         {
>>>>            return 0;
>>>>         }
>>>>       }
>>>>
>>>>     return as_string_;
>>>>   }
>>>>
>>>>   void
>>>>   UUID::from_string_i (const ACE_CString& uuid_string)
>>>>   {
>>>>     if (uuid_string.length() < NIL_UUID.to_string ()->length ())
>>>>       {
>>>>         ACE_ERROR ((LM_ERROR,
>>>>                     "%N ACE_UUID::from_string_i - "
>>>>                     "IllegalArgument(incorrect string length)\n"));
>>>>         return;
>>>>       }
>>>>
>>>>     /// Special case for the nil UUID.
>>>>     if (uuid_string == *NIL_UUID.to_string ())
>>>>       {
>>>>         bool copy_constructor_not_supported = false;
>>>>         ACE_ASSERT (copy_constructor_not_supported);
>>>>         //*this = NIL_UUID;
>>>>         ACE_UNUSED_ARG (copy_constructor_not_supported);
>>>>         return;
>>>>       }
>>>>
>>>>     unsigned int timeLow;
>>>>     unsigned int timeMid;
>>>>     unsigned int timeHiAndVersion;
>>>>     unsigned int clockSeqHiAndReserved;
>>>>     unsigned int clockSeqLow;
>>>>     unsigned int node [UUID_node::NODE_ID_SIZE];
>>>>     char thr_pid_buf [BUFSIZ];
>>>>
>>>>     if (uuid_string.length() == NIL_UUID.to_string()->length())
>>>>       {
>>>>         // This might seem quite strange this being in ACE, but it
>>>>         // seems to be a bit difficult to write a facade for ::sscanf
>>>>         // because some compilers dont support vsscanf, including
>>>>         // MSVC. It appears that most platforms support sscanf though
>>>>         // so we need to use it directly.
>>>>         const int nScanned =
>>>> #if defined (ACE_HAS_TR24731_2005_CRT)
>>>>           sscanf_s (
>>>> #else
>>>>           ::sscanf(
>>>> #endif
>>>>                    uuid_string.c_str(),
>>>>                    "%8x-%4x-%4x-%2x%2x-%2x%2x%2x%2x%2x%2x",
>>>>                    &timeLow,
>>>>                    &timeMid,
>>>>                    &timeHiAndVersion,
>>>>                    &clockSeqHiAndReserved,
>>>>                    &clockSeqLow,
>>>>                    &node[0],
>>>>                    &node[1],
>>>>                    &node[2],
>>>>                    &node[3],
>>>>                    &node[4],
>>>>                    &node[5]
>>>>                    );
>>>>
>>>>         if (nScanned != 11)
>>>>           {
>>>>             ACE_DEBUG ((LM_DEBUG,
>>>>                         "UUID::from_string_i - "
>>>>                         "IllegalArgument(invalid string representation)\n"));
>>>>             return;
>>>>           }
>>>>       }
>>>>     else
>>>>       {
>>>>         const int nScanned =
>>>> #if defined (ACE_HAS_TR24731_2005_CRT)
>>>>           sscanf_s (uuid_string.c_str(),
>>>>                     "%8x-%4x-%4x-%2x%2x-%2x%2x%2x%2x%2x%2x-%s",
>>>>                     &timeLow,
>>>>                     &timeMid,
>>>>                     &timeHiAndVersion,
>>>>                     &clockSeqHiAndReserved,
>>>>                     &clockSeqLow,
>>>>                     &node[0],
>>>>                     &node[1],
>>>>                     &node[2],
>>>>                     &node[3],
>>>>                     &node[4],
>>>>                     &node[5],
>>>>                     thr_pid_buf,
>>>>                     BUFSIZ
>>>>                     );
>>>> #else
>>>>           ::sscanf (uuid_string.c_str(),
>>>>                     "%8x-%4x-%4x-%2x%2x-%2x%2x%2x%2x%2x%2x-%s",
>>>>                     &timeLow,
>>>>                     &timeMid,
>>>>                     &timeHiAndVersion,
>>>>                     &clockSeqHiAndReserved,
>>>>                     &clockSeqLow,
>>>>                     &node[0],
>>>>                     &node[1],
>>>>                     &node[2],
>>>>                     &node[3],
>>>>                     &node[4],
>>>>                     &node[5],
>>>>                     thr_pid_buf
>>>>                     );
>>>> #endif /* ACE_HAS_TR24731_2005_CRT */
>>>>
>>>>         if (nScanned != 12)
>>>>           {
>>>>             ACE_DEBUG ((LM_DEBUG,
>>>>                         "ACE_UUID::from_string_i - "
>>>>                         "IllegalArgument(invalid string representation)\n"));
>>>>             return;
>>>>           }
>>>>       }
>>>>
>>>>     this->timeLow_ = static_cast<ACE_UINT32> (timeLow);
>>>>     this->timeMid_ = static_cast<ACE_UINT16> (timeMid);
>>>>     this->timeHiAndVersion_ = static_cast<ACE_UINT16> (timeHiAndVersion);
>>>>     this->clockSeqHiAndReserved_ = static_cast<u_char> (clockSeqHiAndReserved);
>>>>     this->clockSeqLow_ = static_cast<u_char> (clockSeqLow);
>>>>
>>>>     UUID_node::NodeID nodeID;
>>>>     for (int i = 0; i < UUID_node::NODE_ID_SIZE; ++i)
>>>>       nodeID [i] = static_cast<u_char> (node[i]);
>>>>
>>>>     this->node_->nodeID (nodeID);
>>>>
>>>>     // Support varient 10- only
>>>>     if ((this->clockSeqHiAndReserved_ & 0xc0) != 0x80 && (this->clockSeqHiAndReserved_ & 0xc0) != 0xc0)
>>>>       {
>>>>         ACE_DEBUG ((LM_DEBUG,
>>>>                     "ACE_UUID::from_string_i - "
>>>>                     "IllegalArgument(unsupported variant)\n"));
>>>>         return;
>>>>       }
>>>>
>>>>     /// Support versions 1, 3, and 4 only
>>>>     ACE_UINT16 V1 = this->timeHiAndVersion_;
>>>>
>>>>     if ((V1 & 0xF000) != 0x1000 &&
>>>>         (V1 & 0xF000) != 0x3000 &&
>>>>       (V1 & 0xF000) != 0x4000)
>>>>       {
>>>>         ACE_DEBUG ((LM_DEBUG,
>>>>                     "ACE_UUID::from_string_i - "
>>>>                     "IllegalArgument(unsupported version)\n"));
>>>>         return;
>>>>       }
>>>>     if ((this->clockSeqHiAndReserved_ & 0xc0) == 0xc0)
>>>>       {
>>>>         if (uuid_string.length() == NIL_UUID.to_string()->length())
>>>>           {
>>>>             ACE_DEBUG ((LM_DEBUG,
>>>>                       "ACE_UUID::from_string_i - "
>>>>                         "IllegalArgument (Missing Thread and Process Id)\n"));
>>>>             return;
>>>>           }
>>>>         ACE_CString thr_pid_str (thr_pid_buf);
>>>>         ssize_t pos = static_cast<ssize_t> (thr_pid_str.find ('-'));
>>>>         if (pos == -1)
>>>>           ACE_DEBUG ((LM_DEBUG,
>>>>                       "ACE_UUID::from_string_i - "
>>>>                       "IllegalArgument (Thread and Process Id format incorrect)\n"));
>>>>
>>>>         this->thr_id_ = thr_pid_str.substr (0, pos);
>>>>       this->pid_ = thr_pid_str.substr (pos+1, thr_pid_str.length ()-pos-1);
>>>>       }
>>>>   }
>>>>
>>>>   UUID_Generator::UUID_Generator ()
>>>>     : timeLast_ (0),
>>>>       destroy_lock_ (true)
>>>>   {
>>>>     ACE_NEW (lock_,
>>>>              ACE_SYNCH_MUTEX);
>>>>   }
>>>>
>>>>   UUID_Generator::~UUID_Generator()
>>>>   {
>>>>     if (destroy_lock_)
>>>>       delete lock_;
>>>>   }
>>>>
>>>>   void
>>>>   UUID_Generator::init (void)
>>>>   {
>>>>     ACE_OS::macaddr_node_t macaddress;
>>>>     int result = ACE_OS::getmacaddress (&macaddress);
>>>>
>>>>     UUID_node::NodeID nodeID;
>>>>     if (result != -1)
>>>>       {
>>>> //         ACE_DEBUG ((LM_DEBUG,
>>>> //                     "%02X-%02X-%02X-%02X-%02X-%02X\n",
>>>> //                     macaddress.node [0],
>>>> //                     macaddress.node [1],
>>>> //                     macaddress.node [2],
>>>> //                     macaddress.node [3],
>>>> //                     macaddress.node [4],
>>>> //                     macaddress.node [5]));
>>>>
>>>>         ACE_OS::memcpy (&nodeID,
>>>>                         macaddress.node,
>>>>                         sizeof (nodeID));
>>>>       }
>>>>     else
>>>>       {
>>>>         nodeID [0] = static_cast<u_char> (ACE_OS::rand());
>>>>         nodeID [1] = static_cast<u_char> (ACE_OS::rand());
>>>>         nodeID [2] = static_cast<u_char> (ACE_OS::rand());
>>>>         nodeID [3] = static_cast<u_char> (ACE_OS::rand());
>>>>         nodeID [4] = static_cast<u_char> (ACE_OS::rand());
>>>>         nodeID [5] = static_cast<u_char> (ACE_OS::rand());
>>>>       }
>>>>
>>>> 	ACE_UINT16 dummy;
>>>>     this->get_timestamp (timeLast_,dummy);
>>>>
>>>>     {
>>>>       ACE_GUARD (ACE_SYNCH_MUTEX, ace_mon, *lock_);
>>>>       uuid_state_.timestamp = timeLast_;
>>>>       uuid_state_.node.nodeID (nodeID);
>>>>     }
>>>>   }
>>>>
>>>>
>>>>   void
>>>>   UUID_Generator::generateUUID (UUID& uuid,ACE_UINT16 version, u_char variant)
>>>>   {
>>>>     UUID_time timestamp;
>>>> 	ACE_UINT16 clockSequence;
>>>>     this->get_timestamp (timestamp,clockSequence);
>>>>
>>>>
>>>>     // Construct a Version 1 UUID with the information in the arguements.
>>>>     uuid.timeLow (static_cast<ACE_UINT32> (timestamp & 0xFFFFFFFF));
>>>>     uuid.timeMid (static_cast<ACE_UINT16> ((timestamp >> 32) & 0xFFFF));
>>>>
>>>>
>>>>     ACE_UINT16 tHAV = static_cast<ACE_UINT16> ((timestamp >> 48) & 0xFFFF);
>>>>     tHAV |= (version << 12);
>>>>     uuid.timeHiAndVersion (tHAV);
>>>>
>>>>     u_char cseqHAV;
>>>>     uuid.clockSeqLow (static_cast<u_char> (clockSequence & 0xFF));
>>>>     cseqHAV = static_cast<u_char> ((clockSequence & 0x3f00) >> 8);
>>>>     uuid_state_.timestamp = timestamp;
>>>>
>>>>     cseqHAV |= variant;
>>>>     uuid.clockSeqHiAndReserved (cseqHAV);
>>>>     uuid.node (&(uuid_state_.node));
>>>>
>>>>     if (variant == 0xc0)
>>>>     {
>>>>       ACE_Thread_ID thread_id;
>>>>       char buf [BUFSIZ];
>>>>       thread_id.to_string (buf);
>>>>       uuid.thr_id (buf);
>>>>
>>>>       ACE_OS::sprintf (buf,
>>>>                        "%d",
>>>>                        static_cast<int> (ACE_OS::getpid ()));
>>>>       uuid.pid (buf);
>>>>     }
>>>>   }
>>>>
>>>>   UUID*
>>>>   UUID_Generator::generateUUID (ACE_UINT16 version, u_char variant)
>>>>   {
>>>>     UUID* uuid;
>>>>     ACE_NEW_RETURN (uuid,
>>>>                     UUID,
>>>>                     0);
>>>>
>>>>     this->generateUUID (*uuid, version, variant);
>>>>     return uuid;
>>>>   }
>>>>
>>>>   /// Obtain a new timestamp. If UUID's are being generated too quickly
>>>>   /// the clock sequence will be incremented
>>>>   void
>>>>   UUID_Generator::get_timestamp (UUID_time& timestamp,ACE_UINT16& clockSequence)
>>>>   {
>>>>     ACE_GUARD (ACE_SYNCH_MUTEX, mon, *lock_);
>>>>
>>>>     this->get_systemtime(timestamp);
>>>>
>>>>     // Account for the clock being set back. Increment the clock /
>>>>     // sequence.
>>>>     if (timestamp <= timeLast_)
>>>>       uuid_state_.clockSequence = static_cast<u_char> ((uuid_state_.clockSequence + 1) & ACE_UUID_CLOCK_SEQ_MASK);
>>>>
>>>>     // If the system time ticked since the last UUID was
>>>>     // generated. Set / the clock sequence back.
>>>>     else if (timestamp > timeLast_)
>>>>       uuid_state_.clockSequence = 0;
>>>>
>>>>     timeLast_ = timestamp;
>>>> 	clockSequence = uuid_state_.clockSequence;
>>>>   }
>>>>
>>>>   /**
>>>>    * ACE_Time_Value is in POSIX time, seconds since Jan 1, 1970. UUIDs use
>>>>    * time in 100ns ticks since 15 October 1582. The difference is:
>>>>    *   15 Oct 1582 - 1 Jan 1600: 17 days in Oct, 30 in Nov,  31 in Dec +
>>>>    *       17 years and 4 leap days (1584, 88, 92 and 96)
>>>>    *   1 Jan 1600 - 1 Jan 1900: 3 centuries + 73 leap days ( 25 in 17th cent.
>>>>    *       and 24 each in 18th and 19th centuries)
>>>>    *   1 Jan 1900 - 1 Jan 1970: 70 years + 17 leap days.
>>>>    * This adds up, in days: (17+30+31+365*17+4)+(365*300+73)+(365*70+17) or
>>>>    * 122192928000000000U (0x1B21DD213814000) 100 ns ticks.
>>>>    */
>>>>   void
>>>>   UUID_Generator::get_systemtime (UUID_time & timestamp)
>>>>   {
>>>>     const UUID_time timeOffset =
>>>> #if defined (ACE_LACKS_UNSIGNEDLONGLONG_T)
>>>>       ACE_U_LongLong (ACE_INT64_LITERAL (0x1B21DD213814000));
>>>> #elif defined (ACE_LACKS_LONGLONG_T)
>>>>       ACE_U_LongLong (0x13814000u, 0x1B21DD2u);
>>>> #else
>>>>       ACE_UINT64_LITERAL (0x1B21DD213814000);
>>>> #endif  /* ACE_LACKS_UNSIGNEDLONGLONG_T */
>>>>
>>>>     /// Get the time of day, convert to 100ns ticks then add the offset.
>>>>     ACE_Time_Value now = ACE_OS::gettimeofday();
>>>>     ACE_UINT64 time;
>>>>     now.to_usec (time);
>>>>     time = time * 10;
>>>>     timestamp = time + timeOffset;
>>>> }
>>>>
>>>>   ACE_SYNCH_MUTEX*
>>>>   UUID_Generator::lock (void)
>>>>   {
>>>>     return this->lock_;
>>>>   }
>>>>
>>>>   void
>>>>   UUID_Generator::lock (ACE_SYNCH_MUTEX* lock,
>>>>                         bool release_lock)
>>>>   {
>>>>     if (this->destroy_lock_)
>>>>       delete this->lock_;
>>>>
>>>>     this->lock_ = lock;
>>>>     this->destroy_lock_ = release_lock;
>>>>   }
>>>>
>>>> }
>>>>
>>>> #if defined (ACE_HAS_EXPLICIT_STATIC_TEMPLATE_MEMBER_INSTANTIATION)
>>>> template ACE_Singleton<ACE_Utils::UUID_Generator, ACE_SYNCH_MUTEX> *
>>>>   ACE_Singleton<ACE_Utils::UUID_Generator, ACE_SYNCH_MUTEX>::singleton_;
>>>> #endif /* ACE_HAS_EXPLICIT_STATIC_TEMPLATE_MEMBER_INSTANTIATION */
>>>>
>>>> ACE_END_VERSIONED_NAMESPACE_DECL
>>>> // -*- C++ -*-
>>>>
>>>> //=============================================================================
>>>> /**
>>>>  *  @file  UUID.h
>>>>  *
>>>>  *  $Id: UUID.h 74958 2006-10-23 23:31:00Z ossama $
>>>>  *
>>>>  *  @author Andrew T. Finnel <andrew at activesol.net>
>>>>  *  @author Yamuna Krishnmaurthy <yamuna at oomworks.com>
>>>>  */
>>>> //=============================================================================
>>>>
>>>> #ifndef ACE_UUID_H
>>>> #define ACE_UUID_H
>>>> #include /**/ "ace/pre.h"
>>>>
>>>> #include /**/ "ace/config-all.h"
>>>>
>>>> #if !defined (ACE_LACKS_PRAGMA_ONCE)
>>>> # pragma once
>>>> #endif /* ACE_LACKS_PRAGMA_ONCE */
>>>>
>>>> #include "ace/SString.h"
>>>> #include "ace/Singleton.h"
>>>> #include "ace/Synch_Traits.h"
>>>>
>>>> ACE_BEGIN_VERSIONED_NAMESPACE_DECL
>>>>
>>>> namespace ACE_Utils
>>>> {
>>>>   /// Class to hold a MAC address
>>>>   class ACE_Export UUID_node
>>>>   {
>>>>   public:
>>>>
>>>>     /// Constructor
>>>>     UUID_node (void);
>>>>
>>>>     enum {NODE_ID_SIZE = 6};
>>>>     typedef u_char NodeID[NODE_ID_SIZE];
>>>>
>>>>     NodeID& nodeID (void);
>>>>     void nodeID (NodeID&);
>>>>
>>>>     ///// Equality Operations
>>>>     bool operator == (const UUID_node& right) const;
>>>>     bool operator != (const UUID_node& right) const;
>>>>
>>>>     ///// Relational Operations
>>>>     //bool operator <  (const UUID_node& right) const;
>>>>
>>>>   private:
>>>>     NodeID nodeID_;
>>>>   };
>>>>
>>>>
>>>>
>>>>   /**
>>>>    *  @class ACE_UUID
>>>>    *
>>>>    * ACE_UUID represents a Universally Unique IDentifier (UUID) as
>>>>    * described in (the expired) INTERNET-DRAFT specification entitled
>>>>    * UUIDs and GUIDs. All instances of UUID are of the time-based
>>>>    * variety. That is, the version number part of the timeHiAndVersion
>>>>    * field is 1.
>>>>    *
>>>>    * The default constructor creates a nil UUID.
>>>>    *
>>>>    * UUIDs have value semantics. In addition, they may be compared for
>>>>    * ordering and equality.
>>>>    *
>>>>    * Additionally in this implementation provisions have been made to include
>>>>    * process and thread ids to make the UUIDs more unique. The variant 0xc0
>>>>    * has been added to facilitate this.
>>>>    */
>>>>   class ACE_Export UUID
>>>>   {
>>>>   public:
>>>>
>>>>     /// Constructor
>>>>     UUID (void);
>>>>
>>>>     /// Constructs a UUID from a string representation.
>>>>     UUID (const ACE_CString& uuidString);
>>>>
>>>>     UUID (const UUID &right);
>>>>
>>>>     // Destructor
>>>>     ~UUID (void);
>>>>
>>>>     ACE_UINT32 timeLow (void) const;
>>>>     void timeLow (ACE_UINT32);
>>>>
>>>>     ACE_UINT16 timeMid (void) const;
>>>>     void timeMid (ACE_UINT16);
>>>>
>>>>     ACE_UINT16 timeHiAndVersion (void) const;
>>>>     void timeHiAndVersion (ACE_UINT16);
>>>>
>>>>     u_char clockSeqHiAndReserved (void) const;
>>>>     void clockSeqHiAndReserved (u_char);
>>>>
>>>>     u_char clockSeqLow (void) const;
>>>>     void clockSeqLow (u_char);
>>>>
>>>>     UUID_node* node (void) const;
>>>>     void node (UUID_node*);
>>>>
>>>>     ACE_CString* thr_id (void);
>>>>     void thr_id (char*);
>>>>
>>>>     ACE_CString* pid (void);
>>>>     void pid (char*);
>>>>
>>>>     /// Returns a string representation of the UUID
>>>>     const ACE_CString* to_string (void);
>>>>
>>>>     /// Set the value using a string
>>>>     void from_string (const ACE_CString& uuid_string);
>>>>
>>>>     static UUID NIL_UUID;
>>>>
>>>>     /// Equality Operations
>>>>     bool operator== (const UUID &right) const;
>>>>     bool operator!= (const UUID &right) const;
>>>>
>>>>     /// Relational Operations
>>>>     //bool operator<  (const UUID &right) const;
>>>>     //bool operator>  (const UUID &right) const;
>>>>     //bool operator<= (const UUID &right) const;
>>>>     //bool operator>= (const UUID &right) const;
>>>>
>>>>   private:
>>>>     void from_string_i (const ACE_CString& uuidString);
>>>>
>>>>     UUID& operator= (const UUID&);
>>>>
>>>>     /// Data Members for Class Attributes
>>>>     ACE_UINT32 timeLow_;
>>>>     ACE_UINT16 timeMid_;
>>>>     ACE_UINT16 timeHiAndVersion_;
>>>>     u_char clockSeqHiAndReserved_;
>>>>     u_char clockSeqLow_;
>>>>     UUID_node* node_;
>>>>     bool node_release_;
>>>>     ACE_CString thr_id_;
>>>>     ACE_CString pid_;
>>>>
>>>>     /// The string representation of the UUID. This is created and
>>>>     /// updated only on demand.
>>>>     ACE_CString *as_string_;
>>>>   };
>>>>
>>>>
>>>>   /**
>>>>    * @class ACE_UUID_Generator
>>>>    *
>>>>    * Singleton class that generates UUIDs.
>>>>    *
>>>>    */
>>>>   class ACE_Export UUID_Generator
>>>>   {
>>>>   public:
>>>>
>>>>     enum {ACE_UUID_CLOCK_SEQ_MASK = 0x3FFF};
>>>>
>>>>     UUID_Generator();
>>>>     ~UUID_Generator();
>>>>
>>>>     void init (void);
>>>>
>>>>     /// Format timestamp, clockseq, and nodeID into an UUID of the
>>>>     /// specified version and variant. For generating UUID's with
>>>>     /// thread and process ids use variant=0xc0
>>>>     void generateUUID (UUID&, ACE_UINT16 version=0x0001, u_char variant=0x80);
>>>>
>>>>     /// Format timestamp, clockseq, and nodeID into a VI UUID. For
>>>>     /// generating UUID's with thread and process ids use variant=0xc0
>>>>     UUID* generateUUID (ACE_UINT16 version=0x0001, u_char variant=0x80);
>>>>
>>>>     /// Type to represent UTC as a count of 100 nanosecond intervals
>>>>     /// since 00:00:00.00, 15 October 1582.
>>>>     typedef ACE_UINT64 UUID_time;
>>>>
>>>>     /// The locking strategy prevents multiple generators from accessing
>>>>     /// the UUID_state at the same time. Get the locking strategy.
>>>>     ACE_SYNCH_MUTEX* lock (void);
>>>>
>>>>     /// Set a new locking strategy and return the old one.
>>>>     void lock (ACE_SYNCH_MUTEX* lock,
>>>>                bool release_lock);
>>>>
>>>>   private:
>>>>
>>>>     /// The system time when that last uuid was generated.
>>>>     UUID_time timeLast_;
>>>>
>>>>     /// Type to contain the UUID generator persistent state. This will
>>>>     /// be kept in memory mapped shared memory
>>>>     struct UUID_State
>>>>     {
>>>>       UUID_time timestamp;
>>>>       UUID_node node;
>>>>       ACE_UINT16 clockSequence;
>>>>     };
>>>>
>>>>     /// Obtain a UUID timestamp. Compensate for the fact that the time
>>>>     /// obtained from getSystem time has a resolution less than 100ns.
>>>>   void get_timestamp (UUID_time& timestamp, ACE_UINT16& clockSequence);
>>>>
>>>>     /// Obtain the system time in UTC as a count of 100 nanosecond intervals
>>>>     /// since 00:00:00.00, 15 October 1582 (the date of Gregorian reform to
>>>>   /// the Christian calendar).
>>>>     void get_systemtime( UUID_time& timeNow);
>>>>
>>>>     /// The UUID generator persistent state.
>>>>     UUID_State uuid_state_;
>>>>
>>>>     ACE_SYNCH_MUTEX* lock_;
>>>>     bool destroy_lock_;
>>>>   };
>>>>
>>>>   typedef ACE_Singleton<UUID_Generator, ACE_SYNCH_MUTEX> UUID_GENERATOR;
>>>>
>>>> }
>>>>
>>>> ACE_END_VERSIONED_NAMESPACE_DECL
>>>>
>>>> #if defined (__ACE_INLINE__)
>>>> #include "ace/UUID.inl"
>>>> #endif /* __ACE_INLINE__ */
>>>>
>>>> #include /**/ "ace/post.h"
>>>> #endif // ACE_UUID_H
>>>>     
>>>>         
>>>   
>>>       
>
>
>   



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