hamsterdb Embedded Database 2.0.0.rc3UNSTABLE
We keep track of VERY first free slot index + free slot index pointing at last (~ supposed largest) free range + 'utilization' of the range between FIRST and LAST as a ratio of number of free slots in there vs. total number of slots in that range (giving us a 'fill' ratio) + a fragmentation indication, determined by counting the number of freelist slot searches that FAILed vs. SUCCEEDed within the first..last range, when the search begun at the 'first' position (a FAIL here meaning the freelist scan did not deliver a free slot WITHIN the first..last range, i.e. it has scanned this entire range without finding anything suitably large).
Note that the free_fill in here is AN ESTIMATE.