On quinta-feira, 8 de setembro de 2016 11:35:22 PDT Benjamin TERRIER wrote: > Hi, > > As of Qt 5.7, QUuid::createUuid() documentation is: > > On any platform other than Windows, this function returns a new UUID with > > variant QUuid::DCE and version QUuid::Random. If the /dev/urandom device > > exists, then the numbers used to construct the UUID will be of > > cryptographic quality, which will make the UUID unique. Otherwise, the > > numbers of the UUID will be obtained from the local pseudo-random number > > generator (qrand(), which is seeded by qsrand()) which is usually not of > > cryptograhic quality, which means that the UUID can't be guaranteed to be > > unique. > > > > On a Windows platform, a GUID is generated, which almost certainly will be > > unique, on this or any other system, networked or not. > So according to this there are 3 kinds of UUID: > - Generated by /dev/urandom > - Generated by qrand() > - Generated on Windows OS > > The documentation states explicitly that the first type is unique and > that the 2 last types are not unique.
It says that the first and the last are unique, the middle one isn't. > However, my knowledge is that whatever the method one use to generate > your UUID, one can never guarantee its uniqueness. Meaning that the Qt > documentation is falsely guarantying unique UUID and therefore should > be changed. > > If anyone can confirm, I'll create a bug report. Right, it's not guaranteed. It's just that the chance of collision is virtually zero. -- Thiago Macieira - thiago.macieira (AT) intel.com Software Architect - Intel Open Source Technology Center _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development