ENT-14329: Store only in-use measurement slots#21
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~80 of the 100 slots are consumed by default measurements, leaving little room for custom ones. Raise the limit to 300. Kept in sync: CF_OBSERVABLES and the two cf-check copies of the on-disk struct, plus the OBSERVABLES name table (GetObservable() indexes it for unregistered slots, so a short table crashes cf-monitord). cf-check dump now tolerates the shorter records and ts_key a pre-upgrade agent leaves behind. Ticket: ENT-6511 Changelog: Increased the maximum number of cf-monitord measurement slots (CF_OBSERVABLES) from 100 to 300
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| * The number of bytes of an Averages record that are actually in use. The | ||
| * built-in observables (indices 0..ob_spare-1) are always present; the custom | ||
| * slots above them are used only where a measurement is registered. cf-monitord | ||
| * writes only this many bytes per timekey, so unused trailing slots (up to 200 |
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Raising CF_OBSERVABLES enlarges the fixed-size Averages record, so records written by an older agent are shorter than the current struct. Added a migration (modelled on dbm_migration_lastseen.c) that rewrites old records to the current size, zero-filling the new slots, registered for the observations and history DBs. This replaces the cf-check dump leniency with a one-time on-disk migration; dump only needs to know the new "version" key. Ticket: ENT-6511 Changelog: None
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cf-monitord wrote a full Averages record per timekey regardless of use, so the raised CF_OBSERVABLES cost ~56 MB/host even with no custom measurements. Write only up to the highest in-use slot (AveragesUsedSize); readers zero-and-clamp, so the unused tail reads back as zero. Ticket: ENT-14329 Changelog: cf-monitord stores only in-use measurement slots
GetObservable() returns "spare"/"unused" for unregistered slots instead of
indexing the OBSERVABLES table beyond its named entries, so the table no longer
needs a {"spare","unused"} row per slot.
Ticket: ENT-14329
Changelog: None
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Stacked on the bump (cfengine#6239 / ENT-6511). Draft, unsigned — for review.
GetObservable()synthesizes"spare", soconstants.cdrops 300 → 72 rows.Ticket: ENT-14329