This commit includes concurrency control for datapages, the new backpressure for the c0-c1 merger, and (untested) support for defining NO_SNOWSHOVEL, and using the old approach.
There are a number of important limitations:
- statistics gathering is somewhat messed up
- the c0-c1 merge thread polls for new data
- on a sequential write, if the writers stall, the merge thread could empty memory and initiate an unnecessary merge. Instead, we should never finish a merge if c0 is less than N% full
- this commit introduces yet another batch of nasty mutex contention issues
git-svn-id: svn+ssh://svn.corp.yahoo.com/yahoo/yrl/labs/pnuts/code/logstore@955 8dad8b1f-cf64-0410-95b6-bcf113ffbcfe
Bugfixes:
- Atomically deallocate regions and update the logstore object
- Proactively invalidate iterators after each merge (before, it would simply set a not-valid bit. This doesn't work because iterators hold page pins, which breaks force-writes)
- Clarify semantics of opening iterators mid-stream: All calls now return iterators that return first key >= the requested one. revalidate() needs the key > the requested one, so it calls peek(), then (if necessary) getnext().
- Add asserts to check that the header is latched at update, and that tuples returned by iterators are strictly monotonically increasing'
- Improve error handling in network.h We still get (and terminate on) SIGPIPE.
Refactoring:
- Add dispatch function to network.h.
git-svn-id: svn+ssh://svn.corp.yahoo.com/yahoo/yrl/labs/pnuts/code/logstore@620 8dad8b1f-cf64-0410-95b6-bcf113ffbcfe
The tests now pass, except that check_merge never terminates (it takes too long) and check_mergelarge still is not passing.
For better luck running this version of the code, turn off stasis' concurrent buffer manager. We're doing something bad that leads to deadlocks with the concurrent buffer
manager. Another (the same?) bug less-frequently leads to page corruption with the old stasis buffer manager.
git-svn-id: svn+ssh://svn.corp.yahoo.com/yahoo/yrl/labs/pnuts/code/logstore@556 8dad8b1f-cf64-0410-95b6-bcf113ffbcfe
