This allows for leveled_iclerk:clerk_stop to be a sync call, so that files will only be closed once the iclerk has stopped. This is designed ot prevent iclerk crashes during shutdowns when files it is depnding on are closed mid shutdown.
Warn at startup if this ratio is high. Not sure how snapshots will perform if there are a lot of ledger cache sin the list. However, it should still work. basic_SUITE/load_count test intended to demonstrate that a large ratio is still functional
A test thta will cause leveled to crash due to a low cache size being set - but protect against this (as well as the general scenario of the cache being full).
There could be a potential case where a L0 file present (post pending) without work backlog being set. In this case we want to roll the level zero to memory, but don't accept the cache update if the L0 cache is already full.
logs should always at least have a log_level defined which is in the ?LOG_LEVELS - so the final case of
`-is_active_level([] , _, _) -> false.`
is unnecessary (even if a bad log level is passed in).
correct Bucket and Key definition to hit expected eunit test cases in leveled_pmem
Will not lead to immediate run time changes in SST or CDB logs. These log settings will only change once the new files are re-written.
To completely change the log level - a restart of the store is necessary with new startup options.
Simple change to check for presence of objetc in list before adding it:
```Head check took 124416 microseconds checking list of length 5000
Head check took 130114 microseconds checking list of length 5000
Check for presence of repeated objects
Head check took 1725 microseconds checking list of length 5```
Test fails as fetching repeated object is too slow.
```Head check took 124301 microseconds checking list of length 5000
Head check took 112286 microseconds checking list of length 5000
Head check took 1336512 microseconds checking list of length 5
2018-12-10T11:54:41.342 B0013 <0.2459.0> Long running task took 260788 microseconds with task of type pcl_head
2018-12-10T11:54:41.618 B0013 <0.2459.0> Long running task took 276508 microseconds with task of type pcl_head
2018-12-10T11:54:41.894 B0013 <0.2459.0> Long running task took 275225 microseconds with task of type pcl_head
2018-12-10T11:54:42.173 B0013 <0.2459.0> Long running task took 278836 microseconds with task of type pcl_head
2018-12-10T11:54:42.477 B0013 <0.2459.0> Long running task took 304524 microseconds with task of type pcl_head```
It taks twice as long to check for one repeated object as it does to check for 5K non-repeated objects
