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id-generation.md

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EPF_PersistenceIdGenerator

For persistence a specialized version of the EDF_DbEntityIdGenerator is used. This is because the persistence system needs to account for multiple hives and deterministic GUIDs for baked map objects.

The format is still a GUID but depending on what it is generated for the exact format is different

Dynamic entities and scripted states

647399a8 - 0000 - 0017 - 0001 - 5487 a9003c24
TTTTTTTT SEQ1 SEQ1 HHHH RND1 RND1RND2
  • TTTTTTTT UNIX UTC 32-bit date time stamp. Gives the ID general lexograpical sortability by creation time. Minimizes collisions as each ID becomes unique per second.
  • SEQ1 gives guaranteed uniqueness to the ID due to the combination with the timestamp. Starts at 0 per session. Is incremented by one for each generated ID. There can be skips in the sequence number making their way to the database as not all generated ids will end up being used.
  • HHHH is the hive index with values between (inclusive) 1 and 4095.
  • RND1 and RND2 aim to minimize predictability by malicious actors by introducing pseudo-random numbers. These are however NOT cryptographically safe!

Baked map entities

00bb0001 - 1a79 - 8da7 - 3f92 - 4c9a 1f3582d7
00CCHHHH SPL1 SPL1 SPL2 SPL2 SPL3SPL3
  • 00 The double leading zero lexicographically sorts baked objects as earliest created and gives a hint that the entity in question is in fact baked.
  • CC is the code of the special GUID format, bb is the code for baked map ojects
  • HHHH is the hive index with values between (inclusive) 1 and 4095.
  • SPL1, SPL2, and SPL3 are splits of the deterministic string hash, for the unique identifier, that represents the baked entity (s. baked entities for details).

Root entity collection

00ec0001 - 0000 - 0000 - 0000 - 0000 00000000
00CCHHHH ZERO ZERO ZERO ZERO ZEROZERO
  • 00 The double leading zero lexicographically sorts this special collection with the baked objects
  • CC is the code of the special GUID format, ec is the code for root entity collection
  • HHHH is the hive index with values between (inclusive) 1 and 4095.
  • ZERO always zero groups. There can be only one root entity collection per hive so the hive id is identifier enough.

Local UID replacement

Uids are only available on backend connected dedicated servers. So for local workbench testing purposes a replacement is offered of the same GUID format and based on the order of connection of the main window and additional peer tools.

bbbbdddd - 0000 - 0000 - 0000 - 0000 00000001
BOHEMUID ZERO ZERO ZERO UID1 UID1UID1
  • BOHEMUID Leading indicator bbbbdddd of a local replacement of the Bohemia player UID.
  • ZERO always zero groups.
  • UID1 uid to a length of 12 based on the local connect playerId.