BOOKKEEPER-160: bookie server needs to do compaction over entry log files to reclaim disk space
Review Request #3874 - Created Feb. 12, 2012 and updated
bookie server aggregates entries into entry log file. suppose there is lots of ledgers, each ledger has little messages. so a entry log file would contains messages from lots of different ledgers. if there is only one ledger not be deleted, the entry log file would not be removed, whose occupied disk space could not be reclaimed.