Stop stopping writes on bg_error_

Summary: This might have caused https://github.com/facebook/rocksdb/issues/345. If we're stopping writes and bg_error comes along, we will never unblock the write.

Test Plan: compiles

Reviewers: ljin

Reviewed By: ljin

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24807
Options correction
Merge pull request #352 from fyrz/OptionsTestMergeProblem

Options correction related to merge
WriteBatchWithIndex's Iterator bug of SeekToFirst() and SeekToLast()

Summary: WriteBatchWithIndex's iterator's SeekToFirst() and SeekToLast() use offset=0 to indicate it is smaller than all the keys, which is wrong. offset=0 will decode a key "" (the header decodes like that). It could be larger than other keys in non-default comparators. Fix it by using a special flag of offset to indicate searching to the beginning of the CF.

Test Plan: Add a unit test that used to fail. Also, add some more tests to related cases, though they don't fail for now.

Reviewers: igor

Reviewed By: igor

Subscribers: rven, yhchiang, ljin, leveldb

Differential Revision: https://reviews.facebook.net/D24873
Move logging out of mutex

Summary: As title

Test Plan: compiles

Reviewers: sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24897
Filters getting disposed by System.gc before EOL

Previous to this commit Filters passed as parameters to the
BlockTableConfig are disposed before they should be disposed.

Further Smart pointer usage was corrected.

Java holds now the smart pointer to the FilterPolicy correctly
and cares about freeing underlying c++ structures.
ldb: support --fix_prefix_len

Summary:
ldb to support --fix_prefix_len to allow us to verify more cases.
Also fix a small issue that --bloom_bits might not be applied if --block_size is not given.

Test Plan: run ldb tool against an example DB.

Reviewers: ljin, yhchiang, rven, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24819
make max_write_buffer_number dynamic

Summary: as title

Test Plan: unit test

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D24729
dynamic disable_auto_compactions

Summary: Add more tests as well

Test Plan: unit test

Reviewers: igor, sdong, yhchiang

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24747
dynamic soft_rate_limit and hard_rate_limit

Summary: as title

Test Plan:
unit test
I am only able to build the test case for hard_rate_limit.
soft_rate_limit is essentially the same thing as hard_rate_limit

Reviewers: igor, sdong, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24759
Log MutableCFOptions in SetOptions

Summary: as title

Test Plan: make release

Reviewers: sdong, yhchiang, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24903
fix build failure

Summary: missed default value during merge

Test Plan: ./db_test

Reviewers: igor, sdong, yhchiang

Reviewed By: yhchiang

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D24975
Fix mac compile
Fix mac compile, second try
Total memtables size counter

Summary: Added one new counter for GetProperty

Test Plan: Not sure if needs a test case. compiles

Reviewers: sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D25023
Merge pull request #353 from fyrz/FixBloomfilterRocksJava

[RocksJava] Filters getting disposed by System.gc before EOL
Fix DynamicMemtableOptions test

Summary: as title

Test Plan: make release

Reviewers: igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D25029
[RocksJava] Support Snapshots

Summary:
Snapshots integration into RocksJava. Added support for the following functionalities:

- getSnapshot
- releaseSnapshot
- ReadOptions support to set a Snapshot
- ReadOptions support to retrieve Snapshot
- SnapshotTest

Test Plan:
make rocksdbjava
make jtest

Differential Revision: https://reviews.facebook.net/D24801