Summary:
I've added functions to the C API to support WriteBatchWithIndex as requested in #1833.

I've also added unit tests to c_test

I've implemented the WriteBatchWithIndex variation of every function available for regular WriteBatch.  And added additional functions unique to WriteBatchWithIndex.

For now, the following is omitted:
  1. The ability to create WriteBatchWithIndex's custom batch-only iterator as I'm not sure what its purpose is.  It should be possible to add later if anyone wants it.
  2. The ability to create the batch with a fallback comparator, since it appears to be unnecessary.  I believe the column family comparator will be used for this, meaning those using a custom comparator can just use the column family variations.
Closes https://github.com/facebook/rocksdb/pull/1985

Differential Revision: D4760039

Pulled By: siying

fbshipit-source-id: 393227e

Summary:
Allow set SavePoint to WriteBatch in C ABI.
Closes https://github.com/facebook/rocksdb/pull/1698

Differential Revision: D4378556

Pulled By: yiwu-arbug

fbshipit-source-id: afca746

Summary: Closes https://github.com/facebook/rocksdb/pull/1687

Differential Revision: D4349210

Pulled By: IslamAbdelRahman

fbshipit-source-id: 32d0fbd

Summary:
addfile phase in c_test could fail because in previous steps we did a DeleteRange.
Fix the test by simply moving the addfile phase before DeleteRange
Closes https://github.com/facebook/rocksdb/pull/1672

Differential Revision: D4328896

Pulled By: IslamAbdelRahman

fbshipit-source-id: 1d946df

Summary: Closes https://github.com/facebook/rocksdb/pull/1671

Differential Revision: D4327453

Pulled By: yiwu-arbug

fbshipit-source-id: bcdbc65

Summary:
Seem that writebatch delete range can work now, so I add C API for later use.

Btw, can we use this feature in production now?
Closes https://github.com/facebook/rocksdb/pull/1647

Differential Revision: D4314534

Pulled By: ajkr

fbshipit-source-id: e835165

Summary:
Add C API for CompactRangeOptions.
Closes https://github.com/facebook/rocksdb/pull/1596

Differential Revision: D4252339

Pulled By: yiwu-arbug

fbshipit-source-id: f768f93

Summary:
Add C API to set base_backgroud_compactions
Closes https://github.com/facebook/rocksdb/pull/1571

Differential Revision: D4245709

Pulled By: yiwu-arbug

fbshipit-source-id: 792c6b8

Summary: Closes https://github.com/facebook/rocksdb/pull/1496

Differential Revision: D4168080

Pulled By: siying

fbshipit-source-id: 056ae62

Summary:
Fix the following RocksDB Lite build failure in c_test.cc

db/c_test.c:1051:3: error: implicit declaration of function 'fprintf' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
  fprintf(stderr, "SKIPPED\n");
  ^
db/c_test.c:1051:3: error: declaration of built-in function 'fprintf' requires inclusion of the header <stdio.h> [-Werror,-Wbuiltin-requires-header]
db/c_test.c:1051:11: error: use of undeclared identifier 'stderr'
  fprintf(stderr, "SKIPPED\n");
          ^
3 errors generated.
Closes https://github.com/facebook/rocksdb/pull/1479

Differential Revision: D4151160

Pulled By: yhchiang

fbshipit-source-id: a471a30

Summary:
fix lint error about tabs and duplicate includes.
Closes https://github.com/facebook/rocksdb/pull/1476

Differential Revision: D4149646

Pulled By: lightmark

fbshipit-source-id: 2e0a632

Summary:
support seek_for_prev in c abi.
Closes https://github.com/facebook/rocksdb/pull/1457

Differential Revision: D4135360

Pulled By: lightmark

fbshipit-source-id: 61256b0

Summary:
Add C api for RateLimiter.
Closes https://github.com/facebook/rocksdb/pull/1455

Differential Revision: D4116362

Pulled By: yiwu-arbug

fbshipit-source-id: cb05a8d

Summary:
IngestExternalFile is very useful when doing bulk load. This pr expose this API to c so many bindings can benefit from it too.
Closes https://github.com/facebook/rocksdb/pull/1454

Differential Revision: D4113420

Pulled By: yiwu-arbug

fbshipit-source-id: 307c6ae

* add C api for set wal recovery mode

* add test

Summary:
This adds a new metablock containing a shared dictionary that is used
to compress all data blocks in the SST file. The size of the shared dictionary
is configurable in CompressionOptions and defaults to 0. It's currently only
used for zlib/lz4/lz4hc, but the block will be stored in the SST regardless of
the compression type if the user chooses a nonzero dictionary size.

During compaction, computes the dictionary by randomly sampling the first
output file in each subcompaction. It pre-computes the intervals to sample
by assuming the output file will have the maximum allowable length. In case
the file is smaller, some of the pre-computed sampling intervals can be beyond
end-of-file, in which case we skip over those samples and the dictionary will
be a bit smaller. After the dictionary is generated using the first file in a
subcompaction, it is loaded into the compression library before writing each
block in each subsequent file of that subcompaction.

On the read path, gets the dictionary from the metablock, if it exists. Then,
loads that dictionary into the compression library before reading each block.

Test Plan: new unit test

Reviewers: yhchiang, IslamAbdelRahman, cyan, sdong

Reviewed By: sdong

Subscribers: andrewkr, yoshinorim, kradhakrishnan, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D52287

rocksdb_backup_engine_purge_old_backups for C libraries

Summary: It has been around for a while and it looks like it never found any uses in the wild. It's also complicating our compaction_job code quite a bit. We're deprecating it in 3.13, but will put it back in 3.14 if we actually find users that need this feature.

Test Plan: make check

Reviewers: noetzli, yhchiang, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42405

 Summary: Make RocksDb build and run on Windows to be functionally
 complete and performant. All existing test cases run with no
 regressions. Performance numbers are in the pull-request.

 Test plan: make all of the existing unit tests pass, obtain perf numbers.

 Co-authored-by: Praveen Rao praveensinghrao@outlook.com
 Co-authored-by: Sherlock Huang baihan.huang@gmail.com
 Co-authored-by: Alex Zinoviev alexander.zinoviev@me.com
 Co-authored-by: Dmitri Smirnov dmitrism@microsoft.com

Summary: Block c_test in ROCKSDB_LITE as it's not supported in ROCKSDB_LITE.

Test Plan: c_test

Reviewers: sdong, rven, anthony, kradhakrishnan, IslamAbdelRahman, igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40257

Summary: key_sizes claims that 3rd key is of length 8, but it's really only 3. This diff makes it length 8.

Test Plan: asan c_test works again.

Reviewers: sdong, yhchiang

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D39699

This reverts commit 78382d4b, reversing
changes made to ca8b85ac.

Summary:
This diff contains trivial fixes for 6 scan-build warnings:

**db/c_test.c**
`db` variable is never read. Removed assignment.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-9b77d2.html#EndPath

**db/db_iter.cc**
`skipping` local variable is assigned to false. Then in the next switch block the only "non return" case assign `skipping` to true, the rest cases don't use it and all do return.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-13fca7.html#EndPath

**db/log_reader.cc**
In `bool Reader::SkipToInitialBlock()` `offset_in_block` local variable is assigned to 0 `if (offset_in_block > kBlockSize - 6)` and then never used. Removed the assignment and renamed it to `initial_offset_in_block` to avoid confusion.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-a618dd.html#EndPath

In `bool Reader::ReadRecord(Slice* record, std::string* scratch)` local variable `in_fragmented_record` in switch case `kFullType` block is assigned to false and then does `return` without use. In the other switch case `kFirstType` block the same `in_fragmented_record` is assigned to false, but later assigned to true without prior use. Removed assignment for both cases.
scan-build reprots:
http://home.fburl.com/~sugak/latest20/report-bb86b0.html#EndPath
http://home.fburl.com/~sugak/latest20/report-a975be.html#EndPath

**table/plain_table_key_coding.cc**
Local variable `user_key_size` is assigned when declared. But then in both places where it is used assigned to `static_cast<uint32_t>(key.size() - 8)`. Changed to initialize the variable to the proper value in declaration.
scan-build report:
http://home.fburl.com/~sugak/latest20/report-9e6b86.html#EndPath

**tools/db_stress.cc**
Missing `break` in switch case block. This seems to be a bug. Added missing `break`.

Test Plan:
Make sure all tests are passing and scan-build does not report 'Dead assignment' and 'Dead initialization' bugs.
```lang=bash
% make check
% make analyze
```

Reviewers: meyering, igor, kradhakrishnan, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D33795

Summary:
We need to turn on -Wshorten-64-to-32 for mobile. See D1671432 (internal phabricator) for details.

This diff turns on the warning flag and fixes all the errors. There were also some interesting errors that I might call bugs, especially in plain table. Going forward, I think it makes sense to have this flag turned on and be very very careful when converting 64-bit to 32-bit variables.

Test Plan: compiles

Reviewers: ljin, rven, yhchiang, sdong

Reviewed By: yhchiang

Subscribers: bobbaldwin, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D28689

Summary: as title

Test Plan: ./c_test

Reviewers: igor

Reviewed By: igor

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D28119

Summary:
...and fix all the errors :)

Jim suggested turning on -Wshadow because it helped him fix number of critical bugs in fbcode. I think it's a good idea to be -Wshadow clean.

Test Plan: compiles

Reviewers: yhchiang, rven, sdong, ljin

Reviewed By: ljin

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D27711

Summary:
It was creating BlockBasedTableOptions object in a loop without calling
destroy()

Test Plan: valgrind ./c_test --leak-check=full --show-reachable=yes

Reviewers: sdong, igor

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D22431

Summary:
I will move compression related options in a separate diff since this
diff is already pretty lengthy.
I guess I will also need to change JNI accordingly :(

Test Plan: make all check

Reviewers: yhchiang, igor, sdong

Reviewed By: igor

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D21915

Summary:
Fix the error of c_test.c

Test Plan:
make c_test
./c_test

Previously, the prefix extractor was being supplied with the RocksDB
key instead of a parsed user key. This makes correct interpretation
by calling application fragile or impossible.