the skip/retain/recalc handlign was confusing. This removes the switcheroo between leveled_codec and leveled_iclerk when mkaing the decision.
Also now the building of the accumulator is handled efficiently (not using ++ on the list).
Tried to rmeove as much of ?HEAD tag handling from leveled_head - as we want leveled_head to be only concerned with the head manipulation for object tags (?STD, ?RIAK and user-defined).
To allow for extraction of metadata, and building of head responses - it should eb possible to dynamically and user-defined tags, and functions to treat them.
If no function is defined, revert to the behaviour of the ?STD tag.
More obvious how to extend the code as it is all in one module.
Also add a new field to the standard object metadata tuple that may hold in the future other object metadata base don user-defined functions.
To show how this works, and prove that it does work thta way.
Test may require adjusting if tested on a slow node (e.g. reduce KeyCount or increase TTL)
Both log level and forced_logs. Allows for log_level to be changed at startup ad runtime. Also allow for a list of forced logs, so if log_level is set > info, individual info logs can be forced to be seen (such as to see stats logs).
The function should see the buckets in order, so it accumulates in such a way to reverse the order - it makes sense that the outcome should be in reverse.
This allows for all fold functions to throw an exception to exit out of a fold with all dependencies still closed down as expected.
This was previously available for key folds, which was necessary for the folds to work in Riak (as max_results in index queries depends one xiting the fold with an exception). This change now adds a ct test, and adds support for head folds, object folds (key order) and object folds (sqn order)
Export changes required to support kv_index_tictactree. This will call tictac_hahs, but also needs to know hash of key used in bxor - so that it can control alterations.
Adds support with test for tuplebuckets in Riak keys.
This exposed that there was no filter using the seglist on the in-mmemory keys. This means that if there is no filter applied in the fold_function, many false positives may emerge.
This is probably not a big performance benefit (and indeed for performance it may be better to apply during the leveled_pmem:merge_trees).
Some thought still required as to what is more likely to contribute to future bugs: an extra location using the hash matching found in leveled_sst, or the extra results in the query.
This helps with kv_index_tictcatree with the leveled_so backend. Now this cna do folds over ranges of keys with modified filters (as folds over ranges of keys must go over lal keys if the backend is segment_ordered)
