mv-iterator-prev branch

[matthewvon]

This branch is to address issue: #52

The async NIF release knowingly disable the iterator "prev" support. Implicitly it also disabled all "next" / "prev" combinations. The assumption then was the Riak only used "fold" ... so don't sweat the details. However, other folks use eleveldb outside of Riak and need the support ... this restores the feature.

[uwiger]

Any ETC on this pull request? I'm doing integration this week, and it would be nice to have it. :)

[matthewvon]

uwiger, I was hoping to hear back on the results in your environment ... and we have gotten into a bottleneck on code reviews here. I can likely get this out Thursday.

[uwiger]

I have been testing it with the mnesia test suite (automatically transforming all occurrences of disc_only_copies to use a leveldb backend instead. While this doesn't work 100%, the mv-iterator-prev branch performs at least as well as master (slightly better since prev() actually works).

The mnesia test suite shakes things up quite a lot, but operates on fairly small data sets. I have not yet run tests on this branch with really large tables.

[matthewvon]

"While this doesn't work 100%" ... what is not working 100%: eleveldb, amnesia test suite, something else?

[uwiger]

Sorry for being unclear. The thing that doesn't work 100% is the "transforming all occurrences of disc_only_copies to use a leveldb backend instead" in the mnesia test suite.

[bookshelfdave]

@matthewvon can you make Travis happy?

[matthewvon]

Travis will not be consistently happy with this branch until 1) eleveldb's mv-clean-overlaps is pushed to master and 2) leveldb's mv-valgrind-cleanup is pushed to master. Travis is failing on the RSS test which Jon describes as unreliable. However, I reviewed it sufficiently to find a memory leak that lead to the other two branches. So, we could pull both branches to here, or finish the code review on the other two branches. I recommend the latter ... or ignoring Travis error on RSS.

[bookshelfdave]

is this comment still accurate?

[bookshelfdave]

+1

Test output:

[0]R15B01p:[mv-iterator-prev]prime:~/basho/eleveldb$ ./rebar eunit
==> eleveldb (eunit)
======================== EUnit ========================
module 'basho_bench_driver_eldb'
cacheleak: cacheleak_test_ (module 'cacheleak')...RSS1: 237176
RSS1: 285028
RSS1: 272244
RSS1: 290236
RSS1: 292764
RSS1: 291308
RSS1: 298684
RSS1: 289360
RSS1: 299124
RSS1: 305092
[28.955 s] ok
module 'cleanup'
  cleanup: assumption_test...assumption_test: top
assumption_test: bottom
[0.526 s] ok
  cleanup: open_close_test...[1.007 s] ok
  cleanup: open_exit_test...[1.507 s] ok
  cleanup: iterator_test...[2.697 s] ok
  cleanup: iterator_db_close_test...[2.033 s] ok
  cleanup: iterator_exit_test...[1.511 s] ok
  [done in 9.298 s]
module 'eleveldb'
  eleveldb: open_test...ok
  eleveldb: fold_test...ok
  eleveldb: fold_keys_test...ok
  eleveldb: fold_from_key_test...ok
  eleveldb: destroy_test...ok
  eleveldb: compression_test...ok
  eleveldb: close_test...ok
  eleveldb: close_fold_test...ok
  [done in 0.025 s]
module 'eleveldb_bump'
iterators: prev_test (module 'iterators')...[0.012 s] ok
=======================================================
  All 16 tests passed.

[uwiger]

Thanks.