[C-API] added the possiblity to create a HashSkipList or HashLinkedList to support prefix seeks
Fixed a compile error which tries to check whether a size_t < 0 in env_posix.cc

Summary:
Fixed a compile error which tries to check whether a size_t < 0 in env_posix.cc

util/env_posix.cc:180:16: error: comparison of unsigned expression < 0 is always false [-Werror,-Wtautological-compare]
    } while (r < 0 && errno == EINTR);
             ~ ^ ~
1 error generated.

Test Plan: make check all

Reviewers: igor, haobo

Reviewed By: igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17379
Merge pull request #105 from tecbot/c-api-prefix

[C-API] support prefix seeks
PlainTableIterator::Seek() shouldn't check bloom filter in total order mode

Summary:
In total order mode, iterator's seek() shouldn't check total order.

Also some cleaning up about checking null for shared pointers. I don't know the behavior before it.

This bug was reported by @igor.

Test Plan: test plain_table_db_test

Reviewers: ljin, haobo, igor

Reviewed By: igor

CC: yhchiang, dhruba, igor, leveldb

Differential Revision: https://reviews.facebook.net/D17391
reduce thread count in ThreadLocalTest.ConcurrentReadWriteTest

Summary: to make it less CPU intensive

Test Plan: ran it

Reviewers: igor

Reviewed By: igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D17403
DBIter to use static allocated char array for saved_key_ (if it is not too long)

Summary: DBIter now uses a std::string for saved_key. Based on some profiling, it could be more expensive than we though. Optimize it with the same technique as LookupKey -- if it is short, we copy it to a static allocated char. Otherwise, dynamically allocate memory for it.

Test Plan: make all check

Reviewers: haobo, ljin

Reviewed By: haobo

CC: dhruba, igor, yhchiang, leveldb

Differential Revision: https://reviews.facebook.net/D17289
Add a java api for rocksdb::Options, currently only supports create_if_missing.

Summary:
* [java] Add a java api for rocksdb::Options, currently only supports create_if_missing.
* [java] Add a test for RocksDBException in RocksDBSample.

Test Plan: make jtest

Reviewers: haobo, sdong

Reviewed By: haobo

CC: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D17385