added a purged marker to CFMetaData to avoid hash lookup in CL
last flush auto-closes and unmaps buffer; clean/dirty maps maintained separately and merged as necessary; supports securely discarding unused portion of segment
supports being awoken to flush outside of its flush schedule
switched back to a modified non-blocking allocateFrom(), also supports 'forced' recycling of all in use segments
exposes CLA.forceRecycleAll(), and simplifies discardUnusedSegments()
added support for low-signalling use cases
updated unit tests to match modified behaviour
Vijay's CommitLogStress patch - useful for putting CL through its paces
DROP and NodeTool.drain() now both use CommitLog.forceRecycleAllSegments() to ensure the CL is clean of records prior to their execution
DROP and NodeTool.drain() now both use CommitLog.forceRecycleAllSegments() to ensure the CL is clean of records prior to their execution