Summary:
Allow `Slice` holding nullptr as a sentinel value but not in comparisons. This new restriction eliminates the need for the manual checks in 39ef9005, while still conforming to glibc's `memcmp` API. Thanks siying for the idea. Users may need to migrate, so mentioned it in HISTORY.md.
Closes https://github.com/facebook/rocksdb/pull/2777

Differential Revision: D5686016

Pulled By: ajkr

fbshipit-source-id: 03a2ca3fd9a0ebade9d0d5686c81d59a9534f563

Summary:
The ::Get from DB is not augmented with an overload method that takes a PinnableSlice instead of a string. Transactions however are not yet upgraded to use the new API. As a result, transaction users such as MyRocks cannot benefit from it. This patch updates the transactional API with a PinnableSlice overload.
Closes https://github.com/facebook/rocksdb/pull/2736

Differential Revision: D5645770

Pulled By: maysamyabandeh

fbshipit-source-id: f6af520df902f842de1bcf99bed3e8dfc43ad96d

Summary:
This is the continuation of https://github.com/facebook/rocksdb/pull/2661 for filter partitions. When pin_l0 is set (along with cache_xxx), then open table open the filter partitions are loaded into the cache and pinned there.
Closes https://github.com/facebook/rocksdb/pull/2766

Differential Revision: D5671098

Pulled By: maysamyabandeh

fbshipit-source-id: 174f24018f1d7f1129621e7380287b65b67d2115

Summary:
it doesn't take nullptr according to its declaration in glibc, and calling it in this way causes our sanitizers (ubsan, clang analyze) to fail.
Closes https://github.com/facebook/rocksdb/pull/2776

Differential Revision: D5683260

Pulled By: ajkr

fbshipit-source-id: 114b137ee188172f96eedc43139255cae7bee80a

Summary:
In Java API, `SstFileWriter.put/merge/delete` takes `Slice` type of key and value, which is a Java wrapper object around C++ Slice object.  The Slice object inherited [ `finalize`](https://github.com/facebook/rocksdb/blob/3c327ac2d0fd50bbd82fe1f1af5de909dad769e6/java/src/main/java/org/rocksdb/AbstractNativeReference.java#L69) method, which [added huge overhead](https://softwareengineering.stackexchange.com/questions/288715/is-overriding-object-finalize-really-bad/288753#288753) to JVM while creating new SstFile.

To address this issue, this PR overload the merge method to take Java byte array instead of the Slice object, and added unit test for it.

We also benchmark these two different merge function, where we could see GC Stall reduced from 50%  to 1%, and the throughput increased from 50MB to 200MB.
Closes https://github.com/facebook/rocksdb/pull/2746

Reviewed By: sagar0

Differential Revision: D5653145

Pulled By: scv119

fbshipit-source-id: b55ea58554b573d0b1c6f6170f8d9223811bc4f5

Summary:
The goal is to reduce the number of histogram buckets, particularly now that we print these histograms for each column family. I chose 1.5 as the factor. We can adjust it later to either make buckets more granular or make fewer buckets.
Closes https://github.com/facebook/rocksdb/pull/2139

Differential Revision: D4872076

Pulled By: ajkr

fbshipit-source-id: 87790d782a605506c3d24190a028cecbd7aa564a

Summary:
- Allow setting custom installation prefix.
- Add option to disable building tests.
Closes https://github.com/facebook/rocksdb/pull/2195

Differential Revision: D5054239

Pulled By: sagar0

fbshipit-source-id: 2de6bef8b7eafed60a830e1796b262f9e6f79da0

Summary:
Changes:
* checks if ASAN mode is on, and uses malloc and free in the constructor and destructor
Closes https://github.com/facebook/rocksdb/pull/2767

Differential Revision: D5671243

Pulled By: armishra

fbshipit-source-id: 8e4ad0f7f163400c4effa8617d3b30134119d802

Summary:
If GC kicks in between

* A Get() reads index entry from base db.
* The Get() read from a blob file

The GC can delete the corresponding blob file, making the key not found. Fortunately we have existing logic to avoid deleting a blob file if it is referenced by a snapshot. So the fix is to explicitly create a snapshot before reading index entry from base db.
Closes https://github.com/facebook/rocksdb/pull/2754

Differential Revision: D5655956

Pulled By: yiwu-arbug

fbshipit-source-id: e4ccbc51331362542e7343175bbcbdea5830f544

Summary:
When out of space, blob db should GC the oldest file. The current implementation GC the newest one instead. Fixing it.
Closes https://github.com/facebook/rocksdb/pull/2757

Differential Revision: D5657611

Pulled By: yiwu-arbug

fbshipit-source-id: 56c30a4c52e6ab04551dda8c5c46006d4070b28d

Summary:
add this counter stat to track usage of deletion-dropping optimization. if usage is low, we can delete it to prevent bugs like #2726.
Closes https://github.com/facebook/rocksdb/pull/2761

Differential Revision: D5665421

Pulled By: ajkr

fbshipit-source-id: 881befa2d199838dac88709e7b376a43d304e3d4

Summary:
https://github.com/facebook/rocksdb/pull/2661 mistakenly updates the version. This patch reverts it.
Closes https://github.com/facebook/rocksdb/pull/2760

Differential Revision: D5662089

Pulled By: maysamyabandeh

fbshipit-source-id: f4735e37921c0ced6081a89080c78ac3728aa8bd

Summary:
it's a new feature that'll be released in 5.8, introduced by PR #2498.
Closes https://github.com/facebook/rocksdb/pull/2759

Differential Revision: D5661923

Pulled By: ajkr

fbshipit-source-id: 9ba9f0d146c453715358ef2dd298aa7765649d7c

Summary:
With this PR, we can measure read-amp for queries where perf_context is enabled as follows:

```
SetPerfLevel(kEnableCount);
Get(1, "foo");
double read_amp = static_cast<double>(get_perf_context()->block_read_byte / get_perf_context()->get_read_bytes);
SetPerfLevel(kDisable);
```

Our internal infra enables perf_context for a sampling of queries. So we'll be able to compute the read-amp for the sample set, which can give us a good estimate of read-amp.
Closes https://github.com/facebook/rocksdb/pull/2749

Differential Revision: D5647240

Pulled By: ajkr

fbshipit-source-id: ad73550b06990cf040cc4528fa885360f308ec12

Summary:
This fixes the existing logic for pinning l0 index partitions. The patch preloads the partitions into block cache and pin them if they belong to level 0 and pin_l0 is set.

The drawback is that it does many small IOs when preloading all the partitions into the cache is direct io is enabled. Working for a solution for that.
Closes https://github.com/facebook/rocksdb/pull/2661

Differential Revision: D5554010

Pulled By: maysamyabandeh

fbshipit-source-id: 1e6f32a3524d71355c77d4138516dcfb601ca7b2

Summary:
Changes:
* extended the wait_txn_map to track additional information
* designed circular buffer to store n latest deadlocks' information
* added test coverage to verify the additional information tracked is accurately stored in the buffer
Closes https://github.com/facebook/rocksdb/pull/2630

Differential Revision: D5478025

Pulled By: armishra

fbshipit-source-id: 2b138de7b5a73f5ca554fc3ff8220a3be49f39e7

Summary:
Clang complain about an cast from uint64_t to int32 in db_stress. Fixing it.
Closes https://github.com/facebook/rocksdb/pull/2755

Differential Revision: D5655947

Pulled By: yiwu-arbug

fbshipit-source-id: cfac10e796e0adfef4727090b50975b0d6e2c9be

Summary:
On initial call to BlobDBImpl::WaStats() `all_periods_write_` would be empty, so it will crash when we call pop_front() at line 1627. Apparently it is mean to pop only when `all_periods_write_.size() > kWriteAmplificationStatsPeriods`.

The whole write amp calculation doesn't seems to be correct and it is not being exposed. Will work on it later.

Test Plan
Change kWriteAmplificationStatsPeriodMillisecs to 1000 (1 second) and run db_bench --use_blob_db for 5 minutes.
Closes https://github.com/facebook/rocksdb/pull/2751

Differential Revision: D5648269

Pulled By: yiwu-arbug

fbshipit-source-id: b843d9a09bb5f9e1b713d101ec7b87e54b5115a4

Summary:
Updating Cassandra merge operator to make use of a single merge operand when needed. Single merge operand support has been introduced in #2721.
Closes https://github.com/facebook/rocksdb/pull/2753

Differential Revision: D5652867

Pulled By: sagar0

fbshipit-source-id: b9fbd3196d3ebd0b752626dbf9bec9aa53e3e26a

Summary:
Added a function `MergeOperator::DoesAllowSingleMergeOperand()` to allow invoking a merge operator even with a single merge operand, if overriden.

This is needed for Cassandra-on-RocksDB work. All Cassandra writes are through merges and this will allow a single merge-value to be updated in the merge-operator invoked via a compaction, if needed, due to an expired TTL.
Closes https://github.com/facebook/rocksdb/pull/2721

Differential Revision: D5608706

Pulled By: sagar0

fbshipit-source-id: f299f9f91c4d1ac26e48bd5906e122c1c5e5f3fc

Summary:
PTAL ajkr
Closes https://github.com/facebook/rocksdb/pull/2750

Differential Revision: D5648052

Pulled By: ajkr

fbshipit-source-id: 7cd1ddd61364d5a55a10fdd293fa74b2bf89dd98

Summary:
fix some things that made this command hard to use from CLI:

- use default values for `target_file_size_base` and `max_bytes_for_level_base`. previously we were using small values for these but default value of `write_buffer_size`, which led to enormous number of L1 files.
- failure message for `value_size_mult` too big. previously there was just an assert, so in non-debug mode it'd overrun the value buffer and crash mysteriously.
- only print verification success if there's no failure. before it'd print both in the failure case.
- support `memtable_prefix_bloom_size_ratio`
- support `num_bottom_pri_threads` (universal compaction)
Closes https://github.com/facebook/rocksdb/pull/2741

Differential Revision: D5629495

Pulled By: ajkr

fbshipit-source-id: ddad97d6d4ba0884e7c0f933b0a359712514fc1d

Summary:
the range delete tombstones in memtable should be added to the aggregator even when the memtable's prefix bloom filter tells us the lookup key's not there. This bug could cause data to temporarily reappear until the memtable containing range deletions is flushed.

Reported in #2743.
Closes https://github.com/facebook/rocksdb/pull/2745

Differential Revision: D5639007

Pulled By: ajkr

fbshipit-source-id: 04fc6facb6f978340a3f639536f4ca7c0d73dfc9

Summary:
We forgot to recompute compaction scores after picking a universal compaction like we do in level compaction (https://github.com/facebook/rocksdb/blob/a34b2e388ee51173e44f6aa290f1301c33af9e67/db/compaction_picker.cc#L691-L695). This leads to a fairness issue where we waste compactions on CFs/DB instances that don't need it while others can starve.

Previously, ccecf3f4 fixed the issue for the read-amp-based compaction case; this PR avoids the issue earlier and also for size-ratio-based compactions.
Closes https://github.com/facebook/rocksdb/pull/2688

Differential Revision: D5566191

Pulled By: ajkr

fbshipit-source-id: 010bccb2a107f6a76f3d3022b90aadce5cc48feb

Summary:
Implement the main body of WritePrepared pseudo code. This includes PrepareInternal and CommitInternal, as well as AddCommitted which updates the commit map. It also provides a IsInSnapshot method that could be later called form the read path to decide if a version is in the read snapshot or it should other be skipped.

This patch lacks unit tests and does not attempt to offer an efficient implementation. The idea is that to have the API specified so that we can work on related tasks in parallel.
Closes https://github.com/facebook/rocksdb/pull/2713

Differential Revision: D5640021

Pulled By: maysamyabandeh

fbshipit-source-id: bfa7a05e8d8498811fab714ce4b9c21530514e1c

Summary:
`PartialMergeMulti` implementation is enough for Cassandra, and `PartialMerge` is not required. Implementing both will just duplicate the code.
As per https://github.com/facebook/rocksdb/blob/master/include/rocksdb/merge_operator.h#L130-L135 :

```
  // The default implementation of PartialMergeMulti will use this function
  // as a helper, for backward compatibility.  Any successor class of
  // MergeOperator should either implement PartialMerge or PartialMergeMulti,
  // although implementing PartialMergeMulti is suggested as it is in general
  // more effective to merge multiple operands at a time instead of two
  // operands at a time.
```
Closes https://github.com/facebook/rocksdb/pull/2737

Reviewed By: scv119

Differential Revision: D5633073

Pulled By: sagar0

fbshipit-source-id: ef4fa102c22fec6a0175ed12f5c44c15afe3c8ca

Summary:
Similar to the bug fixed by https://github.com/facebook/rocksdb/pull/2726, FIFO with compaction and kCompactionStyleNone during user customized CompactFiles() with output level to be 0 can suffer from the same problem. Fix it by leveraging the bottommost_level_ flag.
Closes https://github.com/facebook/rocksdb/pull/2735

Differential Revision: D5626906

Pulled By: siying

fbshipit-source-id: 2b148d0461c61dbd986d74655e384419ae442158

Summary:
If ROCKSDB_LITE is defined, a call to abort() is introduced. This call requires stdlib.h.

Build log of unpatched 5.7.1:

http://beefy9.nyi.freebsd.org/data/110amd64-default/447974/logs/rocksdb-lite-5.7.1.log
Closes https://github.com/facebook/rocksdb/pull/2744

Reviewed By: yiwu-arbug

Differential Revision: D5632372

Pulled By: lxcode

fbshipit-source-id: b2a8e692bf14ccf1f875f3a00463e87bba310a2b

Summary:
Support a window of `active_width` keys that rolls through `[0, max_key)` over the duration of the test. Operations only affect keys inside the window. This gives us the ability to detect L0->L0 deletion bug (#2722).
Closes https://github.com/facebook/rocksdb/pull/2739

Differential Revision: D5628555

Pulled By: ajkr

fbshipit-source-id: 9cb2d8f4ab1a7c73f7797b8e19f7094970ea8749

Summary:
Most of the data used here in shell commands is not generated directly from user input but some data (ie: from environment variables) may have been external influenced. It is a good practice to escape this data before using it in a shell command.

Originally D4800264 but we never quite got it merged.

Reviewed By: yiwu-arbug

Differential Revision: D5595052

fbshipit-source-id: c09d8b47fe35fc6a47afb4933ccad9d56ca8d7be

Summary:
Also verify it fixes gcc7 compile failure #2672 (see also #2699)
Closes https://github.com/facebook/rocksdb/pull/2732

Differential Revision: D5620348

Pulled By: yiwu-arbug

fbshipit-source-id: 87db657ab734f23b1bfaaa9db9b9956d10eaef59

Summary:
Some compilers require `-std=c++11` for the `cstdint` header to be available. We already have logic to add `-std=c++11` to `CXXFLAGS` when the compiler is not MSVC; simply reorder CMakeLists.txt so that logic happens before the calls to `CHECK_CXX_SOURCE_COMPILES`.

Additionally add a missing `set(CMAKE_REQUIRED_FLAGS, ...)` before a call to `CHECK_C_SOURCE_COMPILES`.
Closes https://github.com/facebook/rocksdb/pull/2535

Differential Revision: D5384244

Pulled By: yiwu-arbug

fbshipit-source-id: 2dbae4297c5d8ab4636e08b1457ffb2d3e37aef4

Summary:
With some compilers, `-std=c++11` is necessary for <cstdint> to be
available. Pass this flag via $PLATFORM_CXXFLAGS. Fixes #2488.
Closes https://github.com/facebook/rocksdb/pull/2545

Differential Revision: D5620610

Pulled By: yiwu-arbug

fbshipit-source-id: 2f975b8c1ad52e283e677d9a33543abd064f13ce

Summary:
This pr enables linking all the supported compression libraries via cmake.
Closes https://github.com/facebook/rocksdb/pull/2552

Differential Revision: D5620607

Pulled By: yiwu-arbug

fbshipit-source-id: b6949181f305bfdf04a98f898c92fd0caba0c45a

Summary:
- Remove default arch-specified flags.
- Move non-default arch-specific flags to arch-specific param.

Reviewed By: yiwu-arbug

Differential Revision: D5597499

fbshipit-source-id: c53108ac39c73ac36893d3fd9aaf3b5e3080f1ae

Summary: Closes https://github.com/facebook/rocksdb/pull/2730

Differential Revision: D5619256

Pulled By: ajkr

fbshipit-source-id: c80d697eeceab91964259132e58f5cd2219efb93

Summary:
`KeyNotExistsBeyondOutputLevel` didn't consider L0 files' key-ranges. So if a key only was covered by older L0 files' key-ranges, we would incorrectly drop deletions of that key. This PR just skips the deletion-dropping optimization when output level is L0.
Closes https://github.com/facebook/rocksdb/pull/2726

Differential Revision: D5617286

Pulled By: ajkr

fbshipit-source-id: 4bff1396b06d49a828ba4542f249191052915bce

Summary:
- like other subcommands, reporting compression sizes should be specified with the `--command` CLI arg.
- also added `--compression_types` arg as it's useful to restrict the types of compression used, at least in my dictionary compression experiments.
Closes https://github.com/facebook/rocksdb/pull/2706

Differential Revision: D5589520

Pulled By: ajkr

fbshipit-source-id: 305bb4ebcc95eecc8a85523cd3b1050619c9ddc5

Summary:
Previously we could only select the CF on which to operate uniformly at random. This is a limitation, e.g., when testing universal compaction as all CFs would need to run full compaction at roughly the same time, which isn't realistic.

This PR allows the user to specify the probability distribution for selecting CFs via the `--column_family_distribution` argument.
Closes https://github.com/facebook/rocksdb/pull/2677

Differential Revision: D5544436

Pulled By: ajkr

fbshipit-source-id: 478d56260995236ae90895ce5bd51f38882e185a