[core] Use libuuid's uuid_generate_time in TUUID when available#22016
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chrisburr wants to merge 1 commit intoroot-project:masterfrom
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[core] Use libuuid's uuid_generate_time in TUUID when available#22016chrisburr wants to merge 1 commit intoroot-project:masterfrom
chrisburr wants to merge 1 commit intoroot-project:masterfrom
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The existing TUUID v1 generator seeds its per-thread 14-bit clock sequence from `gSystem->Now() + GetPid()`. When many processes start within the same second on a single host, the seeds are nearly identical and all processes share the same MAC-derived node identifier, so UUIDs produced in the same 100ns tick collide (root-project#22015). libuuid's uuid_generate_time coordinates the clock sequence across processes via /var/lib/libuuid/clock.txt (or uuidd), eliminating these collisions while preserving the RFC 4122 v1 wire format. Link Core against uuid::uuid on non-Windows when libuuid is found and delegate generation to uuid_generate_time; fall back to the existing code path on Windows and on systems without libuuid.
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This Pull request:
Uses libuuid to generate UUIDs in a more robust way, avoiding the issues seen with duplicates in LHCb.
Checklist:
This PR fixes #22015