Summary:
Current implementation of the ```read_options.deadline``` option only checks the deadline for random file reads during point lookups. This PR extends the checks to file opens, prefetches and preloads as part of table open.

The main changes are in the ```BlockBasedTable```, partitioned index and filter readers, and ```TableCache``` to take ReadOptions as an additional parameter. In ```BlockBasedTable::Open```, in order to retain existing behavior w.r.t checksum verification and block cache usage, we filter out most of the options in ```ReadOptions``` except ```deadline```. However, having the ```ReadOptions``` gives us more flexibility to honor other options like verify_checksums, fill_cache etc. in the future.

Additional changes in callsites due to function signature changes in ```NewTableReader()``` and ```FilePrefetchBuffer```.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6982

Test Plan: Add new unit tests in db_basic_test

Reviewed By: riversand963

Differential Revision: D22219515

Pulled By: anand1976

fbshipit-source-id: 8a3b92f4a889808013838603aa3ca35229cd501b

Summary:
We are still keeping unity build working. So it's a good idea to add to a pre-commit CI.
A latest GCC docker image just to get a little bit more coverage. Fix three small issues to make it pass.
Also make unity_test to run db_basic_test rather than db_test to cut the test time. There is no point to run expensive tests here. It was set to run db_test before db_basic_test was separated out.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7026

Test Plan: watch tests to pass.

Reviewed By: zhichao-cao

Differential Revision: D22223197

fbshipit-source-id: baa3b6cbb623bf359829b63ce35715c75bcb0ed4

Add a new option for BackupEngine to store table files under shared_checksum using DB session id in the backup filenames (#6997)

Summary:
`BackupableDBOptions::new_naming_for_backup_files` is added. This option is false by default. When it is true, backup table filenames under directory shared_checksum are of the form `<file_number>_<crc32c>_<db_session_id>.sst`.

Note that when this option is true, it comes into effect only when both `share_files_with_checksum` and `share_table_files` are true.

Three new test cases are added.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6997

Test Plan: Passed make check.

Reviewed By: ajkr

Differential Revision: D22098895

Pulled By: gg814

fbshipit-source-id: a1d9145e7fe562d71cde7ac995e17cb24fd42e76

Summary:
It's useful to build RocksDB using a more recent clang version in CI. Add a CircleCI build and fix some issues with it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/7025

Test Plan: See all tests pass.

Reviewed By: pdillinger

Differential Revision: D22215700

fbshipit-source-id: 914a729c2cd3f3ac4a627cc0ac58d4691dca2168

Summary:
New experimental option BBTO::optimize_filters_for_memory builds
filters that maximize their use of "usable size" from malloc_usable_size,
which is also used to compute block cache charges.

Rather than always "rounding up," we track state in the
BloomFilterPolicy object to mix essentially "rounding down" and
"rounding up" so that the average FP rate of all generated filters is
the same as without the option. (YMMV as heavily accessed filters might
be unluckily lower accuracy.)

Thus, the option near-minimizes what the block cache considers as
"memory used" for a given target Bloom filter false positive rate and
Bloom filter implementation. There are no forward or backward
compatibility issues with this change, though it only works on the
format_version=5 Bloom filter.

With Jemalloc, we see about 10% reduction in memory footprint (and block
cache charge) for Bloom filters, but 1-2% increase in storage footprint,
due to encoding efficiency losses (FP rate is non-linear with bits/key).

Why not weighted random round up/down rather than state tracking? By
only requiring malloc_usable_size, we don't actually know what the next
larger and next smaller usable sizes for the allocator are. We pick a
requested size, accept and use whatever usable size it has, and use the
difference to inform our next choice. This allows us to narrow in on the
right balance without tracking/predicting usable sizes.

Why not weight history of generated filter false positive rates by
number of keys? This could lead to excess skew in small filters after
generating a large filter.

Results from filter_bench with jemalloc (irrelevant details omitted):

    (normal keys/filter, but high variance)
    $ ./filter_bench -quick -impl=2 -average_keys_per_filter=30000 -vary_key_count_ratio=0.9
    Build avg ns/key: 29.6278
    Number of filters: 5516
    Total size (MB): 200.046
    Reported total allocated memory (MB): 220.597
    Reported internal fragmentation: 10.2732%
    Bits/key stored: 10.0097
    Average FP rate %: 0.965228
    $ ./filter_bench -quick -impl=2 -average_keys_per_filter=30000 -vary_key_count_ratio=0.9 -optimize_filters_for_memory
    Build avg ns/key: 30.5104
    Number of filters: 5464
    Total size (MB): 200.015
    Reported total allocated memory (MB): 200.322
    Reported internal fragmentation: 0.153709%
    Bits/key stored: 10.1011
    Average FP rate %: 0.966313

    (very few keys / filter, optimization not as effective due to ~59 byte
     internal fragmentation in blocked Bloom filter representation)
    $ ./filter_bench -quick -impl=2 -average_keys_per_filter=1000 -vary_key_count_ratio=0.9
    Build avg ns/key: 29.5649
    Number of filters: 162950
    Total size (MB): 200.001
    Reported total allocated memory (MB): 224.624
    Reported internal fragmentation: 12.3117%
    Bits/key stored: 10.2951
    Average FP rate %: 0.821534
    $ ./filter_bench -quick -impl=2 -average_keys_per_filter=1000 -vary_key_count_ratio=0.9 -optimize_filters_for_memory
    Build avg ns/key: 31.8057
    Number of filters: 159849
    Total size (MB): 200
    Reported total allocated memory (MB): 208.846
    Reported internal fragmentation: 4.42297%
    Bits/key stored: 10.4948
    Average FP rate %: 0.811006

    (high keys/filter)
    $ ./filter_bench -quick -impl=2 -average_keys_per_filter=1000000 -vary_key_count_ratio=0.9
    Build avg ns/key: 29.7017
    Number of filters: 164
    Total size (MB): 200.352
    Reported total allocated memory (MB): 221.5
    Reported internal fragmentation: 10.5552%
    Bits/key stored: 10.0003
    Average FP rate %: 0.969358
    $ ./filter_bench -quick -impl=2 -average_keys_per_filter=1000000 -vary_key_count_ratio=0.9 -optimize_filters_for_memory
    Build avg ns/key: 30.7131
    Number of filters: 160
    Total size (MB): 200.928
    Reported total allocated memory (MB): 200.938
    Reported internal fragmentation: 0.00448054%
    Bits/key stored: 10.1852
    Average FP rate %: 0.963387

And from db_bench (block cache) with jemalloc:

    $ ./db_bench -db=/dev/shm/dbbench.no_optimize -benchmarks=fillrandom -format_version=5 -value_size=90 -bloom_bits=10 -num=2000000 -threads=8 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=false
    $ ./db_bench -db=/dev/shm/dbbench -benchmarks=fillrandom -format_version=5 -value_size=90 -bloom_bits=10 -num=2000000 -threads=8 -optimize_filters_for_memory -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=false
    $ (for FILE in /dev/shm/dbbench.no_optimize/*.sst; do ./sst_dump --file=$FILE --show_properties | grep 'filter block' ; done) | awk '{ t += $4; } END { print t; }'
    17063835
    $ (for FILE in /dev/shm/dbbench/*.sst; do ./sst_dump --file=$FILE --show_properties | grep 'filter block' ; done) | awk '{ t += $4; } END { print t; }'
    17430747
    $ #^ 2.1% additional filter storage
    $ ./db_bench -db=/dev/shm/dbbench.no_optimize -use_existing_db -benchmarks=readrandom,stats -statistics -bloom_bits=10 -num=2000000 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=false -duration=10 -cache_index_and_filter_blocks -cache_size=1000000000
    rocksdb.block.cache.index.add COUNT : 33
    rocksdb.block.cache.index.bytes.insert COUNT : 8440400
    rocksdb.block.cache.filter.add COUNT : 33
    rocksdb.block.cache.filter.bytes.insert COUNT : 21087528
    rocksdb.bloom.filter.useful COUNT : 4963889
    rocksdb.bloom.filter.full.positive COUNT : 1214081
    rocksdb.bloom.filter.full.true.positive COUNT : 1161999
    $ #^ 1.04 % observed FP rate
    $ ./db_bench -db=/dev/shm/dbbench -use_existing_db -benchmarks=readrandom,stats -statistics -bloom_bits=10 -num=2000000 -compaction_style=2 -fifo_compaction_max_table_files_size_mb=10000 -fifo_compaction_allow_compaction=false -optimize_filters_for_memory -duration=10 -cache_index_and_filter_blocks -cache_size=1000000000
    rocksdb.block.cache.index.add COUNT : 33
    rocksdb.block.cache.index.bytes.insert COUNT : 8448592
    rocksdb.block.cache.filter.add COUNT : 33
    rocksdb.block.cache.filter.bytes.insert COUNT : 18220328
    rocksdb.bloom.filter.useful COUNT : 5360933
    rocksdb.bloom.filter.full.positive COUNT : 1321315
    rocksdb.bloom.filter.full.true.positive COUNT : 1262999
    $ #^ 1.08 % observed FP rate, 13.6% less memory usage for filters

(Due to specific key density, this example tends to generate filters that are "worse than average" for internal fragmentation. "Better than average" cases can show little or no improvement.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6427

Test Plan: unit test added, 'make check' with gcc, clang and valgrind

Reviewed By: siying

Differential Revision: D22124374

Pulled By: pdillinger

fbshipit-source-id: f3e3aa152f9043ddf4fae25799e76341d0d8714e

Summary:
Although RocksDB falls over in various other ways with KVs
around 4GB or more, this change fixes how XXH32 and XXH64 were being
called by the block checksum code to support >= 4GB in case that should
ever happen, or the code copied for other uses.

This change is not a schema compatibility issue because the checksum
verification code would checksum the first (block_size + 1) mod 2^32
bytes while the checksum construction code would checksum the first
block_size mod 2^32 plus the compression type byte, meaning the
XXH32/64 checksums for >=4GB block would not match about 255/256 times.

While touching this code, I refactored to consolidate redundant
implementations, improving diagnostics and performance tracking in some
cases. Also used less confusing language in those diagnostics.

Makes https://github.com/facebook/rocksdb/issues/6875 obsolete.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6978

Test Plan:
I was able to write a test for this using an SST file writer
and VerifyChecksum in a reader. The test fails before the fix, though
I'm leaving the test disabled because I don't think it's worth the
expense of running regularly.

Reviewed By: gg814

Differential Revision: D22143260

Pulled By: pdillinger

fbshipit-source-id: 982993d16134e8c50bea2269047f901c1783726e

Summary:
Compressed block cache is disabled in https://github.com/facebook/rocksdb/pull/4650 for no good reason. Re-enable it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6990

Test Plan: Add a unit test to make sure a general function works with read-only DB + compressed block cache.

Reviewed By: ltamasi

Differential Revision: D22072755

fbshipit-source-id: 2a55df6363de23a78979cf6c747526359e5dc7a1

Summary:
`db_id` and `db_session_id` are now part of the table properties for all formats and stored in SST files. This adds about 99 bytes to each new SST file.

The `TablePropertiesNames` for these two identifiers are `rocksdb.creating.db.identity` and `rocksdb.creating.session.identity`.

In addition, SST files generated from SstFileWriter and Repairer have DB identity “SST Writer” and “DB Repairer”, respectively. Their DB session IDs are generated in the same way as `DB::GetDbSessionId`.

A table property test is added.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6983

Test Plan: make check and some manual tests.

Reviewed By: zhichao-cao

Differential Revision: D22048826

Pulled By: gg814

fbshipit-source-id: afdf8c11424a6f509b5c0b06dafad584a80103c9

Summary:
When using parameterized tests, `gtest` sometimes prints the test
parameters. If no other printing method is available, it essentially
produces a hex dump of the object. This can cause issues with valgrind
with types like `TestArgs` in `table_test`, where the object layout has
gaps (with uninitialized contents) due to the members' alignment
requirements. The patch fixes the uninitialized reads by providing an
`operator<<` for `TestArgs` and also makes sure all members are
initialized (in a consistent order) on all code paths.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6980

Test Plan: `valgrind --leak-check=full ./table_test`

Reviewed By: siying

Differential Revision: D22045536

Pulled By: ltamasi

fbshipit-source-id: 6f5920ac28c712d0aa88162fffb80172ed769c32

Summary:
Persistent cache feature caused rocks db crash on windows. I posted a issue for it, https://github.com/facebook/rocksdb/issues/6919. I found this is because no "persistent_cache_key_prefix" is generated for persistent cache. Looking repo history, "GetUniqueIdFromFile" is not implemented on Windows. So my fix is adding "NewId()" function in "persistent_cache" and using it to generate prefix for persistent cache. In this PR, i also re-enable related test cases defined in "db_test2" and "persistent_cache_test" for windows.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6932

Test Plan:
1. run related test cases in "db_test2" and "persistent_cache_test" on windows and see it passed.
2. manually run db_bench.exe with "read_cache_path" and verified.

Reviewed By: riversand963

Differential Revision: D21911608

Pulled By: cheng-chang

fbshipit-source-id: cdfd938d54a385edbb2836b13aaa1d39b0a6f1c2

Summary:
`HarnessTest` in `table_test.cc` currently tests many parameter
combinations sequentially in a loop. This is problematic from
a testing perspective, since if the test fails, we have no way of
knowing how many/which combinations have failed. It can also cause timeouts on
our test system due to the sheer number of combinations tested.
(Specifically, the parallel compression threads parameter added by
https://github.com/facebook/rocksdb/pull/6262 seems to have been the last straw.)
There is some DIY code there that splits the load among eight test cases
but that does not appear to be sufficient anymore.

Instead, the patch turns `HarnessTest` into a parameterized test, so all the
parameter combinations can be tested separately and potentially
concurrently. It also cleans up the tests a little, fixes
`RandomizedLongDB`, which did not get updated when the parallel
compression threads parameter was added, and turns `FooterTests` into a
standalone test case (since it does not actually need a fixture class).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6974

Test Plan: `make check`

Reviewed By: siying

Differential Revision: D22029572

Pulled By: ltamasi

fbshipit-source-id: 51baea670771c33928f2eb3902bd69dcf540aa41

Summary:
This saves up to two key comparisons in block seeks. The first key
comparison saved is a redundant key comparison against the restart key
where the linear scan starts. This comparison is saved in all cases
except when the found key is in the first restart interval. The
second key comparison saved is a redundant key comparison against the
restart key where the linear scan ends. This is only saved in cases
where all keys in the restart interval are less than the target
(probability roughly `1/restart_interval`).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6646

Test Plan:
ran a benchmark with mostly default settings and counted key comparisons

before: `user_key_comparison_count = 19399529`
after: `user_key_comparison_count = 18431498`

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: pdillinger

Differential Revision: D20849707

Pulled By: ajkr

fbshipit-source-id: 1f01c5cd99ea771fd27974046e37b194f1cdcfac

Summary:
Memory pinned by `pin_l0_filter_and_index_blocks_in_cache` needs to be predictable based on user config. This PR makes sure
we do not pin extra memory for large files generated by intra-L0 (see https://github.com/facebook/rocksdb/issues/6889).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6911

Test Plan: unit test

Reviewed By: siying

Differential Revision: D21835818

Pulled By: ajkr

fbshipit-source-id: a11a088549d06bed8aacc2548d266e5983f0ead4

Summary:
In db_options.c, we should avoid including header files in the `db` directory to avoid introducing unnecessary dependency. The reason why `version_edit.h` has been included in `db_options.cc` is because we need two constants, `kUnknownChecksum` and `kUnknownChecksumFuncName`. We can put these two constants as `constexpr` in the public header `file_checksum.h`.

Test plan (devserver):
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6952

Reviewed By: zhichao-cao

Differential Revision: D21925341

Pulled By: riversand963

fbshipit-source-id: 2902f3b74c97f0cf16c58ad24c095c787c3a40e2

Summary:
Remove the dead code in table test.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6946

Test Plan: run table_test

Reviewed By: riversand963

Differential Revision: D21913563

Pulled By: zhichao-cao

fbshipit-source-id: c0aa9f3b95dfe87dd7fb2cd4823784f08cb3ddd3

Summary:
The ```for``` loop in ```VerifyChecksumInBlocks``` only checks ```index_iter->Valid()``` which could be ```false``` either due to reaching the end of the index or, in case of partitioned index, it could be due to a checksum mismatch error when reading a 2nd level index block. Instead of throwing away the index iterator status, we need to return any errors back to the caller.

Tests:
Add a test in block_based_table_reader_test.cc.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6909

Reviewed By: pdillinger

Differential Revision: D21833922

Pulled By: anand1976

fbshipit-source-id: bc778ebf1121dbbdd768689de5183f07a9f0beae

Summary:
Mostly uninitialized values: some probably written before use, but some seem like bugs. Also, destructor needs to be virtual, and possible use-after-free in test
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6935

Test Plan: make check

Reviewed By: siying

Differential Revision: D21885484

Pulled By: pdillinger

fbshipit-source-id: e2e7cb0a0cf196f2b55edd16f0634e81f6cc8e08

Summary:
This reverts commit 8d87e9ce.

Based on offline discussions, it's too early to upgrade to gtest 1.10, as it prevents some developers from using an older version of gtest to integrate to some other systems. Revert it for now.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6923

Reviewed By: pdillinger

Differential Revision: D21864799

fbshipit-source-id: d0726b1ff649fc911b9378f1763316200bd363fc

Summary:
Because ARM and some other platforms have a larger cache line
size, they have a larger minimum filter size, which causes recently
added PartitionedMultiGet test in db_bloom_filter_test to fail on those
platforms. The code would actually end up using larger partitions,
because keys_per_partition_ would be 0 and never == number of keys
added.

The code now attempts to get as close as possible to the small target
size, while fully utilizing that filter size, if the target partition
size is smaller than the minimum filter size.

Also updated the test to break more uniformly across platforms
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6905

Test Plan: updated test, tested on ARM

Reviewed By: anand1976

Differential Revision: D21840639

Pulled By: pdillinger

fbshipit-source-id: 11684b6d35f43d2e98b85ddb2c8dcfd59d670817

Summary:
x.size() -1 or y - 1 can overflow to an extremely large value when x.size() pr y is 0 when they are unsigned type. The end condition of i in the for loop will be extremely large, potentially causes segment fault. Fix them.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6902

Test Plan: pass make asan_check

Reviewed By: ajkr

Differential Revision: D21843767

Pulled By: zhichao-cao

fbshipit-source-id: 5b8b88155ac5a93d86246d832e89905a783bb5a1

Summary:
The implementation of GetApproximateSizes was inconsistent in
its treatment of the size of non-data blocks of SST files, sometimes
including and sometimes now. This was at its worst with large portion
of table file used by filters and querying a small range that crossed
a table boundary: the size estimate would include large filter size.

It's conceivable that someone might want only to know the size in terms
of data blocks, but I believe that's unlikely enough to ignore for now.
Similarly, there's no evidence the internal function AppoximateOffsetOf
is used for anything other than a one-sided ApproximateSize, so I intend
to refactor to remove redundancy in a follow-up commit.

So to fix this, GetApproximateSizes (and implementation details
ApproximateSize and ApproximateOffsetOf) now consistently include in
their returned sizes a portion of table file metadata (incl filters
and indexes) based on the size portion of the data blocks in range. In
other words, if a key range covers data blocks that are X% by size of all
the table's data blocks, returned approximate size is X% of the total
file size. It would technically be more accurate to attribute metadata
based on number of keys, but that's not computationally efficient with
data available and rarely a meaningful difference.

Also includes miscellaneous comment improvements / clarifications.

Also included is a new approximatesizerandom benchmark for db_bench.
No significant performance difference seen with this change, whether ~700 ops/sec with cache_index_and_filter_blocks and small cache or ~150k ops/sec without cache_index_and_filter_blocks.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6784

Test Plan:
Test added to DBTest.ApproximateSizesFilesWithErrorMargin.
Old code running new test...

    [ RUN      ] DBTest.ApproximateSizesFilesWithErrorMargin
    db/db_test.cc:1562: Failure
    Expected: (size) <= (11 * 100), actual: 9478 vs 1100

Other tests updated to reflect consistent accounting of metadata.

Reviewed By: siying

Differential Revision: D21334706

Pulled By: pdillinger

fbshipit-source-id: 6f86870e45213334fedbe9c73b4ebb1d8d611185

Summary:
Release code now depends on gtest, indirectly through including "test_util/testharness.h". This creates multiple problems. One important reason is the definition of IGNORE_STATUS_IF_ERROR() in test_util/testharness.h. Move it to sync_point.h instead.
Note that utilities/cassandra/format.h still depends on "test_util/testharness.h". This will be resolved in a separate diff.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6907

Test Plan: Run all existing tests.

Reviewed By: ajkr

Differential Revision: D21829884

fbshipit-source-id: 9253c19ffde2936f3ae68998210f8e54f645a6e6

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6808

Reviewed By: anand1976

Differential Revision: D21483984

Pulled By: pdillinger

fbshipit-source-id: 70c5eff2bd54ddba469761d95e4cd4611fb8e598

Summary:
We may sometimes read the uncompression dictionary when its not
necessary, when we lookup a key in an SST file but the index indicates
the key is not present. This can happen with index_type 3.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6906

Test Plan: make check

Reviewed By: cheng-chang

Differential Revision: D21828944

Pulled By: anand1976

fbshipit-source-id: 7aef4f0a39548d0874eafefd2687006d2652f9bb

Summary:
Currently we rely on `BlockContents` to implicitly free the allocated scratch buffer, but when IO error happens, it doesn't make sense to construct the `BlockContents` which might be corrupted. In the stress test, we find that `assert(req.result.size() == block_size(handle));` fails because of potential IO errors.

In this PR, we explicitly free the scratch buffer on error without constructing `BlockContents`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6903

Test Plan: watch stress test

Reviewed By: anand1976

Differential Revision: D21823869

Pulled By: cheng-chang

fbshipit-source-id: 5603fc80e9bf3f44a9d7250ddebd871afe1eb89f

Summary:
`IterKey::UpdateInternalKey()` is an error-prone API as it's
incompatible with `IterKey::TrimAppend()`, which is used for
decoding delta-encoded internal keys. This PR stops using it in
`BlockIter`. Instead, it assigns global seqno in a separate `IterKey`'s
buffer when needed. The logic for safely getting a Slice with global
seqno properly assigned is encapsulated in `GlobalSeqnoAppliedKey`.
`BinarySeek()` is also migrated to use this API (previously it ignored
global seqno entirely).
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6843

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=10 -use_existing_db=true -cache_index_and_filter_blocks=false -num=1000000 -cache_size=1048576000 -threads=1 -reads=40000000
```

results:

| DB | code | throughput |
|---|---|---|
| normal_db | master |  267.9 |
| normal_db   |    PR6843 | 254.2 (-5.1%) |
| ingestion_db |   master |  259.6 |
| ingestion_db |   PR6843 | 250.5 (-3.5%) |

Reviewed By: pdillinger

Differential Revision: D21562604

Pulled By: ajkr

fbshipit-source-id: 937596f836930515da8084d11755e1f247dcb264

Summary:
Preliminary user-timestamp support for delete.

If ["a", ts=100] exists, you can delete it by calling `DB::Delete(write_options, key)` in which `write_options.timestamp` points to a `ts` higher than 100.

Implementation
A new ValueType, i.e. `kTypeDeletionWithTimestamp` is added for deletion marker with timestamp.
The reason for a separate `kTypeDeletionWithTimestamp`: RocksDB may drop tombstones (keys with kTypeDeletion) when compacting them to the bottom level. This is OK and useful if timestamp is disabled. When timestamp is enabled, should we still reuse `kTypeDeletion`, we may drop the tombstone with a more recent timestamp, causing deleted keys to re-appear.

Test plan (dev server)
```
make check
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6253

Reviewed By: ltamasi

Differential Revision: D20995328

Pulled By: riversand963

fbshipit-source-id: a9e5c22968ad76f98e3dc6ee0151265a3f0df619

Summary:
1. Add a value_size in read options which limits the cumulative value size of keys read in batches. Once the size exceeds read_options.value_size, all the remaining keys are returned with status Abort without further fetching any key.
2. Add a unit test case MultiGetBatchedValueSizeSimple the reads keys from memory and sst files.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6826

Test Plan:
1. make check -j64
	   2. Add a new unit test case

Reviewed By: anand1976

Differential Revision: D21471483

Pulled By: akankshamahajan15

fbshipit-source-id: dea51b8e76d5d1df38ece8cdb29933b1d798b900

Summary:
If `req.scratch` is an internally allocated buffer, but `raw_block_contents` is not constructed to own `req.scratch`, then `req.scratch` will be leaked.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6879

Test Plan: make asan_check

Reviewed By: anand1976

Differential Revision: D21728498

Pulled By: cheng-chang

fbshipit-source-id: 8fc6a4f2543918c565ddc16ecfad1807eb9a42cf

Summary:
Fix a couple places where direct I/O was used even though it is
unsupported in lite builds.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6867

Test Plan: `LITE=1 make check -j48`

Reviewed By: pdillinger

Differential Revision: D21689185

Pulled By: ajkr

fbshipit-source-id: 3eaa3abf69cd7d0bcaabbcad3bb5a26fb8dd7301

Summary:
Added code for generically handing structs to OptionTypeInfo.  A struct is a collection of variables handled by their own map of OptionTypeInfos.  Examples of structs include Compaction and Cache options.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6425

Reviewed By: siying

Differential Revision: D21668789

Pulled By: zhichao-cao

fbshipit-source-id: 064b110de39dadf82361ed4663f7ac1a535b0b07

Summary:
* Add missing unit test for schema stability of FileChecksumGenCrc32c
  (previously was only comparing to itself)
* A lot of clarifying comments
* Add some assertions for preconditions
* Rename WritableFileWriter::CalculateFileChecksum -> UpdateFileChecksum
* Simplify FileChecksumGenCrc32c with shared functions
* Implement EndianSwapValue to replace unused EndianTransform

And incidentally since I had trouble with 'make check-format' GitHub action disagreeing with local run,
* Output full diagnostic information when 'make check-format' fails in CI
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6861

Test Plan: new unit test passes before & after other changes

Reviewed By: zhichao-cao

Differential Revision: D21667115

Pulled By: pdillinger

fbshipit-source-id: 6a99970f87605aa024fa540c78cd519ff322c3e6

Summary:
If Option.file_checksum_gen_factory is set, rocksdb generates the file checksum during flush and compaction based on the checksum generator created by the factory and store the checksum and function name in vstorage and Manifest.

This PR enable file checksum generation in SstFileWrite and store the checksum and checksum function name in the  ExternalSstFileInfo, such that application can use them for other purpose, for example, ingest the file checksum with files in IngestExternalFile().
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6859

Test Plan: add unit test and pass make asan_check.

Reviewed By: ajkr

Differential Revision: D21656247

Pulled By: zhichao-cao

fbshipit-source-id: 78a3570c76031d8832e3d2de3d6c79cdf2b675d0

Summary:
Currently, in direct IO mode, `MultiGet` retrieves the data blocks one by one instead of in parallel, see `BlockBasedTable::RetrieveMultipleBlocks`.

Since direct IO is supported in `RandomAccessFileReader::MultiRead` in https://github.com/facebook/rocksdb/pull/6446, this PR applies `MultiRead` to `MultiGet` so that the data blocks can be retrieved in parallel.

Also, in direct IO mode and when data blocks are compressed and need to uncompressed, this PR only allocates one continuous aligned buffer to hold the data blocks, and then directly uncompress the blocks to insert into block cache, there is no longer intermediate copies to scratch buffers.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6815

Test Plan:
1. added a new unit test `BlockBasedTableReaderTest::MultiGet`.
2. existing unit tests and stress tests  contain tests against `MultiGet` in direct IO mode.

Reviewed By: anand1976

Differential Revision: D21426347

Pulled By: cheng-chang

fbshipit-source-id: b8446ae0e74152444ef9111e97f8e402ac31b24f

Summary:
sst_dump can issue many file reads from the file system. This doesn't work well with file systems without a OS cache, especially remote file systems. In order to mitigate this problem, several improvements are done:
1. --readahead_size is added, so that users can specify readahead size when scanning the data.
2. Force a 512KB tail readahead, which prevents three I/Os for footer, meta index and property blocks and hopefully index and filter blocks too.
3. Consoldiate SSTDump's I/Os before opening the file for read. Use the same file prefetch buffer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6836

Test Plan: Add a test that covers this new feature.

Reviewed By: pdillinger

Differential Revision: D21516607

fbshipit-source-id: 3ae43526286f67b2f4a5bdedfbc92719d579b87e

Summary:
Currently there is no check for whether BlockBasedTableBuilder will expose
compression error status if compression fails during the table building.
This commit adds fake faulting compressors and a unit test to test such
cases.

This check finds 5 bugs, and this commit also fixes them:

1. Not handling compression failure well in
   BlockBasedTableBuilder::BGWorkWriteRawBlock.
2. verify_compression failing in BlockBasedTableBuilder when used with ZSTD.
3. Wrongly passing the same reference of block contents to
   BlockBasedTableBuilder::CompressAndVerifyBlock in parallel compression.
4. Wrongly setting block_rep->first_key_in_next_block to nullptr in
   BlockBasedTableBuilder::EnterUnbuffered when there are still incoming data
   blocks.
5. Not maintaining variables for compression ratio estimation and first_block
   in BlockBasedTableBuilder::EnterUnbuffered.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6709

Reviewed By: ajkr

Differential Revision: D21236254

fbshipit-source-id: 101f6e62b2bac2b7be72be198adf93cd32a1ff46

Summary:
The error is assigning KeyContext::s to NotFound status in a
table reader for a "not found in this table" case, which skips searching
in later tables, like only a delete should. (The hash search index iterator
is the only one that can return status NotFound even if Valid() == false.)

This was detected by intermittent failure in
MultiThreadedDBTest.MultiThreaded/5, a kHashSearch configuration.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6821

Test Plan: modified existing unit test to reproduce problem

Reviewed By: anand1976

Differential Revision: D21450469

Pulled By: pdillinger

fbshipit-source-id: 7478003684d637dbd491cdac81468041a791be2c

Summary:
Add methods and constructors for handling enums to the OptionTypeInfo.  This change allows enums to be converted/compared without adding a special "type" to the OptionType.

This change addresses a couple of issues:
- It allows new enumerated types to be added to the options without editing the OptionType base class (and related methods)
- It standardizes the procedure for adding enumerated types to the options, reducing potential mistakes
- It moves the enum maps to the location where they are used, allowing them to be static file members rather than global values
- It reduces the number of types and cases that need to be handled in the various OptionType methods
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6423

Reviewed By: siying

Differential Revision: D21408713

Pulled By: zhichao-cao

fbshipit-source-id: fc492af285d011822578b95d186a0fce25d35626

Summary:
There is no systematic mechanism to prevent BlockBasedTableBuilder's status to be set from non-OK to OK. Adding a mechanism to force this will help us prevent failures in the future.

The solution is to only make it possible to set the status code if the status code to set is not OK.

Since the status code passed to CompressAndVerifyBlock() is changed, a mini refactoring is done too so that the output arguments are changed from reference to pointers, based on Google C++ Style.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6776

Test Plan: Run all existing test.

Reviewed By: pdillinger

Differential Revision: D21314382

fbshipit-source-id: 27000c10f1e4c121661e026548d6882066409375

Summary:
Calculate ```IOOptions::timeout``` using ```ReadOptions::deadline``` and pass it to ```FileSystem::Read/FileSystem::MultiRead```. This allows us to impose a tighter bound on the time taken by Get/MultiGet on FileSystem/Envs that support IO timeouts. Even on those that don't support, check in ```RandomAccessFileReader::Read``` and ```MultiRead``` and return ```Status::TimedOut()``` if the deadline is exceeded.

For now, TableReader creation, which might do file opens and reads, are not covered. It will be implemented in another PR.

Tests:
Update existing unit tests to verify the correct timeout value is being passed
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6751

Reviewed By: riversand963

Differential Revision: D21285631

Pulled By: anand1976

fbshipit-source-id: d89af843e5a91ece866e87aa29438b52a65a8567