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
WriteBatch to provide a way for user to query data size directly and only return constant reference of data in Data()

Summary:
WriteBatch::Data() now is easily to be misuse by users. Also, there is no cheap way for user of WriteBatch to know the data size accumulated. This patch fix the problem by:
(1) return a constant reference to Data() so it's obvious to caller what it means.
(2) add a function to return data size directly

Test Plan: make all check

Reviewers: haobo, igor, kailiu

Reviewed By: kailiu

CC: zshao, leveldb

Differential Revision: https://reviews.facebook.net/D15123
Compile dynamic library by default

Summary:
Per request, some users need to use dynamic rocksdb library instead of static one.

However currently the dynamic libraries have to be manually compiled by default, which is inconvenient. I made dymamic libraries to be compiled by default.

Test Plan: make clean; make; make clean;

Reviewers: haobo, sdong, dhruba, igor

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15117
DB::Put() to estimate write batch data size needed and pre-allocate buffer

Summary:
In one of CPU profiles, we see some CPU costs of string::reserve() inside Batch.Put(). This patch should be able to reduce some of the costs by allocating sufficient buffer before hand.

Since it is a trivial percentage of CPU costs, I didn't find a way to show the improvement in one of the benchmarks. I'll deploy it to same application and do the same CPU profiling to make sure those CPU costs are reduced.

Test Plan: make all check

Reviewers: haobo, kailiu, igor

Reviewed By: haobo

CC: leveldb, nkg-

Differential Revision: https://reviews.facebook.net/D15135
Pre-calculate whether to slow down for too many level 0 files

Summary: Currently in DBImpl::MakeRoomForWrite(), we do  "versions_->NumLevelFiles(0) >= options_.level0_slowdown_writes_trigger" to check whether the writer thread needs to slow down. However, versions_->NumLevelFiles(0) is slightly more expensive than we expected. By caching the result of the comparison when installing a new version, we can avoid this function call every time.

Test Plan:
make all check
Manually trigger this behavior by applying universal compaction style and make sure inserts are made slow after there are certain number of files.

Reviewers: haobo, kailiu, igor

Reviewed By: kailiu

CC: nkg-, leveldb

Differential Revision: https://reviews.facebook.net/D15141
Use sanitized options while opening db

Summary: We use SanitizeOptions() to set appropriate values for some options, based on other options. So we should use the sanitized options by default. Luckily it hasn't caused a bug yet, but can result in a bug in the fugture.

Test Plan: make check

Reviewers: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D14103
A script that automatically reformat affected lines

Summary:
Added a script that reformat only the affected lines in a given diff.

I planned to make that file as pre-commit hook but looks it's a little bit more difficult than I thought. Since I don't want to spend too much time on this task right now, I eventually added a "make command" to achieve this with a few additional key strokes.

Also make the clang-format solely inherited from Google's style -- there are still debates on some of the style issues, but we can address them later once we reach a consensus.

Test Plan: Did some ugly format change and ran "make format", all affected lines are formatted as expected.

Reviewers: igor, sdong, haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D15147
Merge branch 'master' of github.com:facebook/rocksdb into sanitizedOptions
Move the compilation of the shared libraries to "make release"

Compiling the shared libraries took a long time. Thus to speed up the development speed, it still makes sense to be separated from regular compilation.