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From "Albert Lee (JIRA)" <j...@apache.org>
Subject [jira] Closed: (OPENJPA-361) Incorrect GREG_OFFSET offset or inconsistent usage in UUIDGenerator
Date Tue, 30 Oct 2007 14:43:51 GMT

     [ https://issues.apache.org/jira/browse/OPENJPA-361?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Albert Lee closed OPENJPA-361.
------------------------------


> Incorrect GREG_OFFSET offset or inconsistent usage in UUIDGenerator
> -------------------------------------------------------------------
>
>                 Key: OPENJPA-361
>                 URL: https://issues.apache.org/jira/browse/OPENJPA-361
>             Project: OpenJPA
>          Issue Type: Bug
>          Components: lib
>    Affects Versions: 1.0.0
>         Environment: All platforms
>            Reporter: Albert Lee
>            Assignee: Albert Lee
>            Priority: Trivial
>             Fix For: 1.0.1, 1.1.0
>
>         Attachments: OPENJPA-361.patch
>
>
> In UUIDGenerator, GREG_OFFSET is defined as
>     // offset to move from 1/1/1970, which is 0-time for Java, to gregorian
>     // 0-time 10/15/1582, and multiplier to go from 100nsec to msec units
>     private static final long GREG_OFFSET = 0x01b21dd213814000L;
> This constant is used as:
>         // calculate time as current millis plus offset times 100 ns ticks
>         long currentTime = (_currentMillis + GREG_OFFSET) * MILLI_MULT;
> Based of the usage, GREG_OFFSET should be in msec unit and this value should be
>     (1970-1582) * 365.25 * 24 * 3600 * 1000 (ms) = 12,219,292,800,000 (ms) = 0xB1D 069B
5400 (ms)
> The defined constant value 0x1b21dd213814000L is the last value in 100ns unit not ms.

> This also offsets the currentTime calculation off by a factor of 10**4.
> To correct the discrepency, either:
> 1) GREG_OFFSET should assign the value of 0xB1D 069B 5400L instead of 0x1b2 1dd2 1381
4000L, or
> 2) long currentTime = (_currentMillis * MILLI_MULT ) + GREG_OFFSET ;
> Since UUID is an arbituary value, therefore I don't believe the current implementation
is "incorrect" but just inconsistent in its implementation description. 
> Please comment on if:
> 1) the suggested change will have any undesirable side-effect for UUID
> 2) there is any legacy/backward compatibility problem
> 3) this is worth to change at all.
> If there is no objection, I'll correct the "problem" early next week.
> Albert Lee.

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