Summary:
This PR implements a fault injection mechanism for injecting errors in reads in db_stress. The FaultInjectionTestFS is used for this purpose. A thread local structure is used to track the errors, so that each db_stress thread can independently enable/disable error injection and verify observed errors against expected errors. This is initially enabled only for Get and MultiGet, but can be extended to iterator as well once its proven stable.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6538

Test Plan:
crash_test
make check

Reviewed By: riversand963

Differential Revision: D20714347

Pulled By: anand1976

fbshipit-source-id: d7598321d4a2d72bda0ced57411a337a91d87dc7

Summary:
When dynamically linking two binaries together, different builds of RocksDB from two sources might cause errors. To provide a tool for user to solve the problem, the RocksDB namespace is changed to a flag which can be overridden in build time.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6433

Test Plan: Build release, all and jtest. Try to build with ROCKSDB_NAMESPACE with another flag.

Differential Revision: D19977691

fbshipit-source-id: aa7f2d0972e1c31d75339ac48478f34f6cfcfb3e

Summary:
Undo https://github.com/facebook/rocksdb/issues/6243 and fix the crash test failures.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6273

Test Plan: Run make ubsan_crash_test

Differential Revision: D19331472

Pulled By: anand1976

fbshipit-source-id: 30aa4a36c1b0f77a97159d82bbfd1cd767878e28

Summary:
When called on transactions, MultiGet could return a legit MergeInProgress status. The patch excludes this case from errors.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6257

Differential Revision: D19275787

Pulled By: maysamyabandeh

fbshipit-source-id: f7158229422af015947e592ae066b4273c9fb9a4

Summary:
Stress tests count number of errors and report them at the end. Not all the cases are accompanied with a log line which makes debugging difficult. The patch adds a log line to the remaining cases.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6256

Differential Revision: D19268785

Pulled By: maysamyabandeh

fbshipit-source-id: bdabcaa5c5c7edcb4ce4f25e38fd8a3fd9c7700b

Summary:
Clang analyzer was falsely reporting on use of txn=nullptr.
Added a new const variable so that it can properly prune impossible
control flows.

Also, 'make analyze' previously required setting USE_CLANG=1 as an
environment variable, not a make variable, or else compilation errors
like

g++: error: unrecognized command line option ‘-Wshorten-64-to-32’

Now USE_CLANG is not required for 'make analyze' (it's implied) and you
can do an incremental analysis (recompile what has changed) with
'USE_CLANG=1 make analyze_incremental'
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6244

Test Plan: 'make -j24 analyze', 'make crash_test'

Differential Revision: D19225950

Pulled By: pdillinger

fbshipit-source-id: 14f4039aa552228826a2de62b2671450e0fed3cb

Summary:
This commit is suspected in some crash test failures such as

Verification failed for column family 0 key 78438077: Value not found: NotFound:
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6243

Test Plan: 'make check' and start 'make crash_test'

Differential Revision: D19220495

Pulled By: pdillinger

fbshipit-source-id: 6c4709cee80ab4344e06ce360f51e947d79fb3fa

Summary:
Seeing crash test failures like

db_stress: db_stress_tool/no_batched_ops_stress.cc:271: virtual
rocksdb::Status
rocksdb::NonBatchedOpsStressTest::TestPrefixScan(rocksdb::ThreadState*,
const rocksdb::ReadOptions&, const std::vector<int>&, const
std::vector<long int>&): Assertion `count <=
GetPrefixKeyCount(prefix.ToString(), upper_bound)' failed.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6238

Differential Revision: D19210312

Pulled By: pdillinger

fbshipit-source-id: 4d2c35c38f418b408e01c7ba22adf6983ae67d44

Summary:
Call Transaction::MultiGet from TestMultiGet() in db_stress. We add some Puts/Merges/Deletes into the transaction in order to exercise MultiGetFromBatchAndDB. There is no data verification on read, just check status. There is currently no read data verification in db_stress as it requires synchronization with writes. It needs to be tackled separately.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6227

Test Plan: make crash_test_with_txn

Differential Revision: D19204611

Pulled By: anand1976

fbshipit-source-id: 770d0e30d002e88626c264c58103f1d709bb060c

Summary:
Currently, db_stress generates fixed length keys of 8 bytes. This patch adds the ability to generate variable length keys. Most of the db_stress code continues to work with a numeric key randomly generated, and the numeric key also acts as an index into the values_ array. The numeric key is mapped to a variable length string key in a deterministic way. Furthermore, the ordering is preserved.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6165

Test Plan: run make crash_test

Differential Revision: D19204646

Pulled By: anand1976

fbshipit-source-id: d2d46a96615b4832a8be2a981f5913905f0e1ca7

Summary:
Several improvements to crash_test/stress_test:
(1) Stress_test to support an parameter of bottommost compression
(2) Rename those FLAGS_* variables that are not gflags to avoid confusion
(3) Crash_test to randomly generate compression type for bottommost compression with half the chance.
(4) Stress_test to sanitize unsupported compression type to snappy, so that crash_test to cover all possible compression types and people don't need to worry about they don't support all comrpession types in their environment.
(5) In crash_test, when generating db_stress command, sort arguments in alphabeta order, so that it is easier to find value for a specific argument.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6215

Test Plan: Run "make crash_test" for a while and see the botommost option shown in LOG files.

Differential Revision: D19171255

fbshipit-source-id: d7001e246c4ff9ee5760776eea0be97738650735

Summary:
Currently, db_stress performs verification by calling `VerifyDb()` at the end of test and optionally before tests start. In case of corruption or incorrect result, it will be too late. This PR adds more verification in two ways.
1. For cf consistency test, each test thread takes a snapshot and verifies every N ops. N is configurable via `-verify_db_one_in`. This option is not supported in other stress tests.
2. For cf consistency test, we use another background thread in which a secondary instance periodically tails the primary (interval is configurable). We verify the secondary. Once an error is detected, we terminate the test and report. This does not affect other stress tests.

Test plan (devserver)
```
$./db_stress -test_cf_consistency -verify_db_one_in=0 -ops_per_thread=100000 -continuous_verification_interval=100
$./db_stress -test_cf_consistency -verify_db_one_in=1000 -ops_per_thread=10000 -continuous_verification_interval=0
$make crash_test
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6173

Differential Revision: D19047367

Pulled By: riversand963

fbshipit-source-id: aeed584ad71f9310c111445f34975e5ab47a0615

Summary:
And clean up related code, especially in stress test.

(More clean up of db_stress_test_base.cc coming after this.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6154

Test Plan: make check, make blackbox_crash_test for a bit

Differential Revision: D18938180

Pulled By: pdillinger

fbshipit-source-id: 524d27621b8dbb25f6dff40f1081e7c00630357e

Summary:
Two changes:
1. Prevent static variables in a header file
2. Add "override" keyword when virtual functions are overridden.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6137

Test Plan: Build db_stress with or without LITE.

Differential Revision: D18892007

fbshipit-source-id: 295356427a34473b23ed36d6ed4ef3ae35a32db0

Summary:
db_stress_tool.cc now is a giant file. In order to main it easier to improve and maintain, break it down to multiple source files.
Most classes are turned into their own files. Separate .h and .cc files are created for gflag definiations. Another .h and .cc files are created for some common functions. Some test execution logic that is only loosely related to class StressTest is moved to db_stress_driver.h and db_stress_driver.cc. All the files are located under db_stress_tool/. The directory name is created as such because if we end it with either stress or test, .gitignore will ignore any file under it and makes it prone to issues in developements.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6134

Test Plan: Build under GCC7 with and without LITE on using GNU Make. Build with GCC 4.8. Build with cmake with -DWITH_TOOL=1

Differential Revision: D18876064

fbshipit-source-id: b25d0a7451840f31ac0f5ebb0068785f783fdf7d