Summary:
Add "examples" build (which build examples folder in rocksdb) in TravisCI to CircleCI. This is helpful before pull request.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7136

Test Plan: Watch for CircleCI results to succeed

Reviewed By: jay-zhuang

Differential Revision: D22555528

Pulled By: akankshamahajan15

fbshipit-source-id: 6bca16647760d5f0131f064765fe9e88e034c578

Summary:
TSAN shows warning with clang with warning similar to this:

WARNING: ThreadSanitizer: data race (pid=10159)
  Atomic write of size 8 at 0x7b5000002890 by thread T33:
    #0 __tsan_atomic64_store <null> (db_test+0x4ca2b5)
    https://github.com/facebook/rocksdb/issues/1 std::__atomic_base<unsigned long>::store(unsigned long, std::memory_order) /usr/bin/../lib/gcc/x86_64-linux-gnu/5.4.0/../../../../include/c++/5.4.0/bits/atomic_base.h:374:2 (db_test+0x774fde)
    https://github.com/facebook/rocksdb/issues/2 rocksdb::VersionSet::SetLastSequence(unsigned long) /home/circleci/project/./db/version_set.h:1057:20 (db_test+0x774fde)
    https://github.com/facebook/rocksdb/issues/3 rocksdb::DBImpl::WriteImpl(rocksdb::WriteOptions const&, rocksdb::WriteBatch*, rocksdb::WriteCallback*, unsigned long*, unsigned long, bool, unsigned long*, unsigned long, rocksdb::PreReleaseCallback*) /home/circleci/project/db/db_impl/db_impl_write.cc:449:18 (db_test+0x774fde)
......
  Previous read of size 8 at 0x7b5000002890 by thread T5 (mutexes: write M1044689462619020832):
    #0 rocksdb::DBImpl::ReleaseSnapshot(rocksdb::Snapshot const*) /home/circleci/project/db/db_impl/db_impl.cc (db_test+0x6f4ae7)
    https://github.com/facebook/rocksdb/issues/1 rocksdb::(anonymous namespace)::MTThreadBody(void*) /home/circleci/project/db/db_test.cc:2514:13 (db_test+0x56ac59)
    https://github.com/facebook/rocksdb/issues/2 rocksdb::(anonymous namespace)::StartThreadWrapper(void*) /home/circleci/project/env/env_posix.cc:443:3 (db_test+0x88c4cd)

It is not limited to ReleaseSnapshot() and rocksdb::DBImpl::MultiCFSnapshot().

While we are not 100% sure it doesn't indicate any correctness violation, we suppress them for now to keep TSAN clean with more tests so that we can cover more bugs with CI.

In the gcc runs we have been running, this warning rarely shows up.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7126

Test Plan: See the mini-TSAN test to pass with reasonable run time.

Reviewed By: ajkr

Differential Revision: D22552375

fbshipit-source-id: ebdd3854cb3becec3403970326a1ca961db2ab00

Summary:
In both cases where `BlobDBImpl::DecompressSlice` is called,
`compression_type` is already checked at the call site; thus, the check
inside the method is redundant and can be turned into an assertion.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7127

Test Plan: `make check`

Reviewed By: zhichao-cao

Differential Revision: D22533454

Pulled By: ltamasi

fbshipit-source-id: ae524443fc6abe0a5fb12327a3fe761a9cd2c831

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7135

Reviewed By: siying

Differential Revision: D22553594

Pulled By: jay-zhuang

fbshipit-source-id: 5b40621ffad05c4fffe3ac536a11d6c87e7ef512

Summary:
In current codebase, in write path, if Retryable IO Error happens, SetBGError is called. The retryable IO Error is converted to hard error and DB is in read only mode. User or application needs to resume it. In this PR, if Retryable IO Error happens in one DB, SetBGError will create a new thread to call Resume (auto resume). otpions.max_bgerror_resume_count controls if auto resume is enabled or not (if max_bgerror_resume_count<=0, auto resume will not be enabled). options.bgerror_resume_retry_interval controls the time interval to call Resume again if the previous resume fails due to the Retryable IO Error. If non-retryable error happens during resume, auto resume will terminate.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/6765

Test Plan: Added the unit test cases in error_handler_fs_test and pass make asan_check

Reviewed By: anand1976

Differential Revision: D21916789

Pulled By: zhichao-cao

fbshipit-source-id: acb8b5e5dc3167adfa9425a5b7fc104f6b95cb0b

Summary:
Fix typo in ThreadData comment

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7131

Reviewed By: riversand963

Differential Revision: D22543135

Pulled By: jay-zhuang

fbshipit-source-id: 39c9d0e8cd5a364af9a2f05fd3783e8482dea976

Summary:
Currently, RocksDB lets compaction to go through even in case of
corrupted keys, the number of which is reported in CompactionJobStats.
However, RocksDB does not check this value. We should let compaction run
in a stricter mode.

Temporarily disable two tests that allow corrupted keys in compaction.
With this PR, the two tests will assert(false) and terminate. Still need
to investigate what is the recommended google-test way of doing it.
Death test (EXPECT_DEATH) in gtest has warnings now.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7124

Test Plan: make check

Reviewed By: ajkr

Differential Revision: D22530722

Pulled By: riversand963

fbshipit-source-id: 6a5a6a992028c6d4f92cb74693c92db462ae4ad6

Summary:
https://github.com/facebook/rocksdb/pull/6850, which added compaction
filter support to BlobDB, reused elements of the BlobDB GC mechanism.
This patch updates some log messages in this logic to account for this
fact; namely, it replaces mentions of "GC" with "compaction/GC" to avoid
confusion in cases when GC is not enabled.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7128

Test Plan: `make check`

Reviewed By: zhichao-cao

Differential Revision: D22535371

Pulled By: ltamasi

fbshipit-source-id: 1f14f3b02ab9983728bbca1cf680420208d9a195

Summary:
This fixes an issue introduced in 0c56fc4d whereby the location of Python is evaluated many times and leads to excessive logging of unknown python locations of CentOS 6.

The location is now only checked once.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7123

Reviewed By: zhichao-cao

Differential Revision: D22532274

Pulled By: ajkr

fbshipit-source-id: cade71b4b46e9a23d63ecb4dd36a4ac8ae217970

Summary:
It is helpful to add some TSAN coverage before a pull request is committed. This diff adds some of them.
Some slow tests are excluded for the running speed. Some are blacklisted because they show warnings. Will investigate these warnings and see whether we can fix or suppress them.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7122

Test Plan: Watch CIrcleCI runs

Reviewed By: riversand963

Differential Revision: D22532133

fbshipit-source-id: 81ddd02d9df19c513a12811979e8ddabae911354

Summary:
Periodic syncing of blob files is performed by `WritableFileWriter`;
`bytes_per_sync_` and `next_sync_offset_` in `BlobLogWriter` are
actually unused (or more precisely, only used by methods that are
themselves unused). The patch removes all this dead code.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7125

Test Plan: `make check`

Reviewed By: riversand963

Differential Revision: D22531021

Pulled By: ltamasi

fbshipit-source-id: 6b293ad5a79d3e6bf15c5c68f7aedd7ce7a15f10

Summary:
Add stress test coverage for `DB::GetProperty()`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7111

Test Plan:
```
./db_stress -get_property_one_in=1
make crash_test
```

Reviewed By: ajkr

Differential Revision: D22487906

Pulled By: jay-zhuang

fbshipit-source-id: c118d95cc9b4e2fa669a06e6aa531541fa885dc5

Summary:
During memtable lookup, an unrecognized value type should be reported as
Status::Corruption.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7121

Test Plan: make check

Reviewed By: cheng-chang

Differential Revision: D22512124

Pulled By: riversand963

fbshipit-source-id: 9b97be7d9b230c5aae9205f96054420e5ea09066

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7120

Test Plan: Watch CI results.

Reviewed By: cheng-chang

Differential Revision: D22516995

fbshipit-source-id: ddf7c0482dfac30d9044b833852348eda987cb67

Summary:
1. Add the wrapper classes FileSystemTracingWrapper, FSSequentialFileTracingWrapper, FSRandomAccessFileTracingWrapper, FSWritableFileTracingWrapper, FSRandomRWFileTracingWrapper that forward the calls to underlying storage system and then pass the file operation information to IOTracer. IOTracer dumps the record in binary format for tracing.
2. Add the wrapper classes FileSystemPtr, FSSequentialFilePtr, FSRandomAccessFilePtr, FSWritableFilePtr and FSRandomRWFilePtr that overload operator-> and return ptr to underlying storage system or Tracing wrapper class based on enabling/disabling of IO tracing. These classes are added to bypass Tracing Wrapper classes when we disable tracing.
3. Add enums in trace.h that distinguish which options need to be added for different file operations(Read, close, write etc) as part of tracing record.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7002

Test Plan: make check -j64

Reviewed By: anand1976

Differential Revision: D22127897

Pulled By: akankshamahajan15

fbshipit-source-id: 74cff58ce5661c9a3832dfaa52483f3b2d8565e0

Summary:
Add circleci java build workflow.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7119

Reviewed By: siying

Differential Revision: D22512426

Pulled By: jay-zhuang

fbshipit-source-id: 45a7445c861fee48017bae42cdb7172c8b091475

Summary:
CLANG analyze is useful before pull request. Add it.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7114

Test Plan: Watch the CI results to succeed.

Reviewed By: riversand963

Differential Revision: D22491942

fbshipit-source-id: 9ccad91c6142fedc3d3dd491cf55054827908f36

Summary:
It is useful to run UBSAN before merging a PR. This commit adds it. We see warning for stl_tree.h, suppress the warning to make it work.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7112

Test Plan: See the CI to succeed. Manually ingest a UBSAN warning and see it got reported.

Reviewed By: pdillinger

Differential Revision: D22490519

fbshipit-source-id: e4495a0c78a3e2dae7dbf294da79585e141cbb66

Summary:
Closes https://github.com/facebook/rocksdb/issues/6729

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7088

Reviewed By: riversand963

Differential Revision: D22481624

Pulled By: pdillinger

fbshipit-source-id: 27c0ebd4168d374ae81f3595e034150c1c97f8b8

Summary:
Along with https://github.com/facebook/rocksdb/issues/6925 and https://github.com/facebook/rocksdb/issues/6998, this should add getters for all Options fields except several ones with non-trivial interface (for example rocksdb_options_set_min_level_to_compress).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7094

Reviewed By: riversand963

Differential Revision: D22479800

Pulled By: pdillinger

fbshipit-source-id: d14f305e12cfe268d07e0fe229d55cef299c792a

Summary:
Closes https://github.com/facebook/rocksdb/issues/7053

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7090

Reviewed By: riversand963

Differential Revision: D22481199

Pulled By: pdillinger

fbshipit-source-id: 287477db94d57b18bee58189135f44936f1c3ca3

Summary:
There currently exist multiple `GetChildren()` calls in `DBImpl::Recover()`, which can be expensive in cases of distributed file systems.
This pull request try to call `DBImpl::Recover()` of each necessary directory only _once_ and reuse the results in the places of repeated calls in current code.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7044

Test Plan:
Run `make check` and use the default test suite. The modified code should be semantically identical to the current code. As a proof of this solution, we may optionally deploy the system onto a (real or simulated) distributed system and expect reduced latency caused by manifest fetching.

(WIP)

Reviewed By: riversand963

Differential Revision: D22419925

Pulled By: roghnin

fbshipit-source-id: d3774fbfbc246c5527101bc16747eb5c90919886

Summary:
In status.cc, the assert is `assert(sizeof(msgs) > index)`; msgs is a const char* array, sizeof(msgs) is the array size*char* size, which will make the assert pass all the time. Change it to sizeof(msgs)/sizeof(char*) > index.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7045

Test Plan: pass make check

Reviewed By: cheng-chang

Differential Revision: D22291337

Pulled By: zhichao-cao

fbshipit-source-id: 4ba8ebbb8da80ace7ca6adcdb0c66726f993659d

Summary:
Cleans up some of the dependencies on test code in the Makefile while building tools:
- Moves the test::RandomString, DBBaseTest::RandomString into Random
- Moves the test::RandomHumanReadableString into Random
- Moves the DestroyDir method into file_utils
- Moves the SetupSyncPointsToMockDirectIO into sync_point.
- Moves the FaultInjection Env and FS classes under env

These changes allow all of the tools to build without dependencies on test_util, thereby simplifying the build dependencies.  By moving the FaultInjection code, the dependency in db_stress on different libraries for debug vs release was eliminated.

Tested both release and debug builds via Make and CMake for both static and shared libraries.

More work remains to clean up how the tools are built and remove some unnecessary dependencies.  There is also more work that should be done to get the Makefile and CMake to align in their builds -- what is in the libraries and the sizes of the executables are different.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7097

Reviewed By: riversand963

Differential Revision: D22463160

Pulled By: pdillinger

fbshipit-source-id: e19462b53324ab3f0b7c72459dbc73165cc382b2

Summary:
This is a followup to https://github.com/facebook/rocksdb/issues/6646. In that PR, for simplicity I just appended a comparison against the 0th restart key in case `BinarySeek()`'s binary search landed at index 0. As a result there were `2/(N+1) + log_2(N)` key comparisons. This PR does it differently. Now we expand the binary search range by one so it also covers the case where target is at or before the restart key at index 0. As a result, it involves `log_2(N+1)` key comparisons.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7068

Test Plan:
ran readrandom with mostly default settings and counted key comparisons
using `PerfContext`.

before: `user_key_comparison_count = 28881965`
after: `user_key_comparison_count = 27823245`

setup command:

```
$ TEST_TMPDIR=/dev/shm/dbbench ./db_bench -benchmarks=fillrandom,compact -write_buffer_size=1048576 -target_file_size_base=1048576 -max_bytes_for_level_base=4194304 -max_background_jobs=12 -level_compaction_dynamic_level_bytes=true -num=10000000
```

benchmark command:

```
$ TEST_TMPDIR=/dev/shm/dbbench/ ./db_bench -use_existing_db=true -benchmarks=readrandom -disable_auto_compactions=true -num=10000000 -compression_type=none -reads=1000000 -perf_level=3
```

Reviewed By: anand1976

Differential Revision: D22357032

Pulled By: ajkr

fbshipit-source-id: 8b01e9c1c2a4e9d02fc9dfe16c1cc0327f8bdf24

Summary:
As title. The goal is to shorten the execution time of several tests
when they are combined together in a single TEST_F.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7105

Test Plan:
make db_wal_test
./db_wal_test

Reviewed By: ltamasi

Differential Revision: D22442705

Pulled By: riversand963

fbshipit-source-id: 0ad49b8f21fa86dcd5a4d3c9a06af313735ac217

Summary:
as title.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7107

Test Plan: make ldb && ./ldb

Reviewed By: pdillinger

Differential Revision: D22451399

Pulled By: riversand963

fbshipit-source-id: 797645e06473bb9cf139c533877e5161281515e8

Summary:
Although PR https://github.com/facebook/rocksdb/issues/7032 fixes the construction of the `SstFileDumper` in `GetFileDbIdentities` by setting a proper `Env` of the `Options` passed in the constructor, the file path was not corrected accordingly. This actually disables backup engine to use db session ids in the file names since the `db_session_id` is always empty.

Now it is fixed by setting the correct path in the construction of `SstFileDumper`. Furthermore, to preserve the Direct IO property that backup engine already has, parameter `EnvOptions` is added to `GetFileDbIdentities` and `SstFileDumper`.

The `BackupUsingDirectIO` test is updated accordingly.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7104

Test Plan: backupable_db_test and some manual tests.

Reviewed By: ajkr

Differential Revision: D22443245

Pulled By: gg814

fbshipit-source-id: 056a9bb8b82947c5e73d7c3fbb62bfe23af5e562

Update Flush policy in PartitionedIndexBuilder on switching from user-key to internal-key mode (#7096)

Summary:
When format_version is high enough to support user-key and
there are index entries for same user key that spans multiple data
blocks then it changes from user-key mode to internal-key mode. But the
flush policy is not reset to point to Block Builder of internal-keys.
After this switch, no entries are added to user key index partition
result, thus it never triggers flushing the block.

Fix: 1. After adding the entry in sub_builder_index_, if there is a switch
from user-key to internal-key, then flush policy is updated to point to
Block Builder of internal-keys index partition.
2. Set sub_builder_index_->seperator_is_key_plus_seq_ = true if
seperator_is_key_plus_seq_  is set to true so that subsequent partitions
can also use internal key mode.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7096

Test Plan: make check -j64

Reviewed By: ajkr

Differential Revision: D22416598

Pulled By: akankshamahajan15

fbshipit-source-id: 01fc2dc07ea1b32f8fb803995ebe6e9a3fbe67ac

Summary:
WITH_TESTS=OFF and WITH_BENCHMARK_TOOLS=ON

there has errors:
 /bin/ld: cannot find -ltestharness

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7040

Reviewed By: riversand963

Differential Revision: D22447637

Pulled By: ajkr

fbshipit-source-id: f63058376deb4a2e6722d63541c40caa617c331a

Summary:
Delicious copy-pasta from https://github.com/facebook/rocksdb/issues/7039

Also fixing DestroyDir to allow files to go missing while it is operating. This seems to fix failures I got with test plan reproducer.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7103

Test Plan:
make blackbox_crash_test_with_atomic_flush for a while with
checkpoint_one_in=100

Reviewed By: siying

Differential Revision: D22435315

Pulled By: pdillinger

fbshipit-source-id: 0ec0538402493887aeda43ecc03f32979cb84ced

Summary:
The fix in PR https://github.com/facebook/rocksdb/issues/7082 is not really successful because there is still a small chance that the test will fail.

In addtion to flushing, we close the DB and then reopen before corrupting a table file in the DB. Specifically, we corrupt a table file before backup takes place as follows.
* Open DB
* Fill DB
* Flush DB (optional, no flushing here also works)
* Close DB
* Reopen DB
* Corrupt a table file in the DB

This should make the test reliable.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7102

Test Plan:
`while ./backupable_db_test --gtest_filter=*TableFileCorruptedBeforeBackup*; do true; done`
(kept running for an hour or so :)

Reviewed By: pdillinger

Differential Revision: D22432417

Pulled By: gg814

fbshipit-source-id: d407eee93ff428bb662f80cde1659fbf0149d0cd

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7092

Reviewed By: riversand963

Differential Revision: D22412323

Pulled By: ajkr

fbshipit-source-id: 3fc1c63bb19a8cd2c0ae620800c28f199a7f494b

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/7080

Reviewed By: riversand963

Differential Revision: D22412352

Pulled By: ajkr

fbshipit-source-id: 1d7f4c1621040a0130245139b52c3f4d3deac865

Summary:
Currently, `EventListener` in listner.h only have callback functions for file read and write. One may favor extended callback functions for more file I/O operations like flush, sync and close. This PR tries to add those interface and have them called when appropriate throughout the code base.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7055

Test Plan:
Write an experimental listener with those new callback functions with log output in them; run experiments and check logs to see those functions are actually called.
Default test suits `make check` should also be included.

Reviewed By: riversand963

Differential Revision: D22380624

Pulled By: roghnin

fbshipit-source-id: 4121491d45c2c2aae8c255e7998090559a241c6a

Summary:
Replace `BlockIter::comparator_` and `IndexBlockIter::user_comparator_wrapper_` with a concrete `UserComparatorWrapper` and `InternalKeyComparator`. The motivation for this change was the inconvenience of not knowing the concrete type of `BlockIter::comparator_`, which prevented calling specialized internal key comparison functions to optimize comparison of keys with global seqno applied.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/6944

Test Plan:
benchmark setup -- single file DBs, in-memory, no compression. "normal_db"
created by regular flush; "ingestion_db" created by ingesting a file. Both
DBs have same contents.

```
$ TEST_TMPDIR=/dev/shm/normal_db/ ./db_bench -benchmarks=fillrandom,compact -write_buffer_size=10485760000 -disable_auto_compactions=true -compression_type=none -num=1000000
$ ./ldb write_extern_sst ./tmp.sst --db=/dev/shm/ingestion_db/dbbench/ --compression_type=no --hex --create_if_missing < <(./sst_dump --command=scan --output_hex --file=/dev/shm/normal_db/dbbench/000007.sst | awk 'began {print "0x" substr($1, 2, length($1) - 2), "==>", "0x" $5} ; /^Sst file format: block-based/ {began=1}')
$ ./ldb ingest_extern_sst ./tmp.sst --db=/dev/shm/ingestion_db/dbbench/
```

benchmark run command:

```
$ TEST_TMPDIR=/dev/shm/$DB/ ./db_bench -benchmarks=seekrandom -seek_nexts=$SEEK_NEXT -use_existing_db=true -cache_index_and_filter_blocks=false -num=1000000 -cache_size=0 -threads=1 -reads=200000000 -mmap_read=1 -verify_checksum=false
```

results: perf improved marginally for ingestion_db and did not change significantly for normal_db:

SEEK_NEXT | DB | code | ops/sec | % change
-- | -- | -- | -- | --
0 | normal_db | master | 350880 |  
0 | normal_db | PR6944 | 351040 | 0.0
0 | ingestion_db | master | 343255 |  
0 | ingestion_db | PR6944 | 349424 | 1.8
10 | normal_db | master | 218711 |  
10 | normal_db | PR6944 | 217892 | -0.4
10 | ingestion_db | master | 220334 |  
10 | ingestion_db | PR6944 | 226437 | 2.8

Reviewed By: pdillinger

Differential Revision: D21924676

Pulled By: ajkr

fbshipit-source-id: ea4288a2eefa8112eb6c651a671c1de18c12e538

Summary:
On some platforms like MacOS, a second 'make check' can lead to
/bin/rm: Argument list too long

This is fixed by replacing with a 'find'. Also, using '-f' for more rm calls
to avoid prompt.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7095

Test Plan: 'make check' on Linux and MacOS

Reviewed By: riversand963

Differential Revision: D22415808

Pulled By: pdillinger

fbshipit-source-id: 0fd1ebae13739c9d81f9e813e99b062715604d6b

Summary:
by tracking and linking against runtime dependent libraries in
Makefile

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7098

Test Plan: look for fix in CircleCI

Reviewed By: riversand963

Differential Revision: D22420860

Pulled By: pdillinger

fbshipit-source-id: d211d709214bf5306db68e43b7a2f18169281022

Summary:
Fix a Facebook internal build

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7093

Test Plan:
buck build mode/opt :c_test :c_test_bin (was compilation
failure, now "not found")
buck build mode/dev :c_test :c_test_bin (still passes)

Reviewed By: ajkr

Differential Revision: D22412528

Pulled By: pdillinger

fbshipit-source-id: 8e55c43dbf95386597e4cc690c41d9cbdcee03aa

Summary:
Primarily, this change adds a way to work around a bug limiting the effective output (and therefore debugability) of the Linux builds using parallel make. We would get
make[1]: write error: stdout
probably due to a kernel bug, apparently affecting both available ubuntu 16 machine images (maybe not affecting docker images, less horsepower). https://bugs.launchpad.net/ubuntu/+source/linux-signed/+bug/1814393

Now in the CircleCI config, make output on Ubuntu is piped through a custom 'cat' that ignores EAGAIN errors, which seems to fix the problem.

Significant other changes:
* Add another linux build that combines
  * LIB_MODE=shared, to ensure this works with compile and unit test execution
  * Alternative rocksdb namespace, to ensure this works (not rely on Travis)
  * ASSERT_STATUS_CHECKED=1, but with building all unit tests and running those expected to pass with it
* Run release build with and without gflags. (Was running only without, ignore large swaths of code in a normal release build! Two regressions in this build, only with gflags, in the last week not caught by CI!)
* Use gflags with unity and LITE build, as typical case.

Debugability improvements:
* Use V=1 to show commands being executed (thanks to EAGAIN work-around)
* Print kernel version and compiler versions as part of V=1 output from Makefile

Cosmetic other changes:
* Put more commands on one line, for less clutter in CircleCI output pages
* Remove redundant "all" in "make all check" and put make command options before targets
* Change some recursive "make clean" into dependency on "clean," toward minimizing unnecessary overhead (detect platform, build version, etc.) of extra recursive makes

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7078

Reviewed By: siying

Differential Revision: D22391647

Pulled By: pdillinger

fbshipit-source-id: d446fccf5a8c568b37dc8748621c8a5c546fe135