C API: add rocksdb_env_set_high_priority_background_threads
Merge pull request #59 from mlin/more-c-bindings

C API: add rocksdb_env_set_high_priority_background_threads
Don't always compress L0 files written by memtable flush

Summary:
Code was always compressing L0 files written by a memtable flush
when compression was enabled. Now this is done when
min_level_to_compress=0 for leveled compaction and when
universal_compaction_size_percent=-1 for universal compaction.

Task ID: #3416472

Blame Rev:

Test Plan:
ran db_bench with compression options

Revert Plan:

Database Impact:

Memcache Impact:

Other Notes:

EImportant:

- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -

Reviewers: dhruba, igor, sdong

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D14757
Separate the aligned and unaligned memory allocation

Summary: Use two vectors for different types of memory allocation.

Test Plan: run all unit tests.

Reviewers: haobo, sdong

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15027
StopWatch not to get time if it is created for statistics and it is disabled

Summary: Currently, even if statistics is not enabled, StopWatch only for the stats still gets the time of the day, which is wasteful. This patch adds a new option to StopWatch to disable this get in this case.

Test Plan: make all check

Reviewers: dhruba, haobo, igor

CC: leveldb

Differential Revision: https://reviews.facebook.net/D14703
readwhilewriting benchmark

Summary:
Added readwhilewriting benchmark to our regression tests.
Changed block cache shards from 16 to 64, as Mark found that cache mutex contention is a big bottleneck.

Test Plan: Ran it.

Reviewers: dhruba, haobo, MarkCallaghan, xjin

Reviewed By: MarkCallaghan

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15075
Feature requests for BackupableDB

Summary:
This diff introduces some features that were requested by two internal customers:
* Ability for backups not to share table files, because we can't guarantee that equal filename means equal content accross replicas
* Ability for two threads to call EnableFileDeletions() and DisableFileDeletions()
* Ability to stop backup from another thread and not slow down the DB close
* Copy the files to the temporary folder first and then atomically rename

Test Plan: Added some tests to backupable_db_test

Reviewers: dhruba, sanketh, muthu, sdong, haobo

Reviewed By: haobo

CC: leveldb, sanketh, muthu

Differential Revision: https://reviews.facebook.net/D14769
fix compile warning
Merge pull request #61 from Yancey1989/master

fix compile warning
Fix share_table_files condition in BackupEngine constructor.

That makes BackupableDBTest.NoDoubleCopy test error.
Merge pull request #62 from matope/fix-BackupableDBTest-NoDoubleCopy-test-fail

Fix share_table_files condition in BackupEngine constructor.
Improve RocksDB "get" performance by computing merge result in memtable

Summary:
Added an option (max_successive_merges) that can be used to specify the
maximum number of successive merge operations on a key in the memtable.
This can be used to improve performance of the "get" operation. If many
successive merge operations are performed on a key, the performance of "get"
operations on the key deteriorates, as the value has to be computed for each
"get" operation by applying all the successive merge operations.

FB Task ID: #3428853

Test Plan:
make all check
db_bench --benchmarks=readrandommergerandom
counter_stress_test

Reviewers: haobo, vamsi, dhruba, sdong

Reviewed By: haobo

CC: zshao

Differential Revision: https://reviews.facebook.net/D14991
Use ASSERT_EQ() instead of assert() in merge_test
Merge branch 'master' into columnfamilies