Summary:
In the current db_stress, all the keys are generated randomly and follows the uniform distribution. In order to test some corner cases that some key are always updated or read, we need to generate the key based on other distributions. In this PR, the key is generated based on Zipfian distribution and the skewness can be controlled by setting hot_key_alpha (0.8 to 1.5 is suggested). The larger hot_key_alpha is, the more skewed will be. Not that, usually, if hot_key_alpha is larger than 2, there might be only 1 or 2 keys that are generated. If hot_key_alpha is 0, it generate the key follows uniform distribution (random key)

Testing plan: pass the db_stress and printed the keys to make sure it follows the distribution.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6163

Differential Revision: D18978480

Pulled By: zhichao-cao

fbshipit-source-id: e123b4865477f7478e83fb581f9576bada334680

Summary:
https://github.com/facebook/rocksdb/pull/6177 introduced a data race
involving `MemTableList::InstallNewVersion` and `MemTableList::NumFlushed`.
The patch fixes this by caching whether the current version has any
memtable history (i.e. flushed memtables that are kept around for
transaction conflict checking) in an `std::atomic<bool>` member called
`current_has_history_`, similarly to how `current_memory_usage_excluding_last_`
is handled.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6187

Test Plan:
```
make clean
COMPILE_WITH_TSAN=1 make db_test -j24
./db_test
```

Differential Revision: D19084059

Pulled By: ltamasi

fbshipit-source-id: 327a5af9700fb7102baea2cc8903c085f69543b9

Summary:
The filter bits builder collects all the hashes to add in memory before adding them (because the number of keys is not known until we've walked over all the keys). Existing code uses a std::vector for this, which can mean up to 2x than necessary space allocated (and not freed) and up to ~2x write amplification in memory. Using std::deque uses close to minimal space (for large filters, the only time it matters), no write amplification, frees memory while building, and no need for large contiguous memory area. The only cost is more calls to allocator, which does not appear to matter, at least in benchmark test.

For now, this change only applies to the new (format_version=5) Bloom filter implementation, to ease before-and-after comparison downstream.

Temporary memory use during build is about the only way the new Bloom filter could regress vs. the old (because of upgrade to 64-bit hash) and that should only matter for full filters. This change should largely mitigate that potential regression.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6175

Test Plan:
Using filter_bench with -new_builder option and 6M keys per filter is like large full filter (improvement). 10k keys and no -new_builder is like partitioned filters (about the same). (Corresponding configurations run simultaneously on devserver.)

std::vector impl (before)

    $ /usr/bin/time -v ./filter_bench -impl=2 -quick -new_builder -working_mem_size_mb=1000 -
    average_keys_per_filter=6000000
    Build avg ns/key: 52.2027
    Maximum resident set size (kbytes): 1105016
    $ /usr/bin/time -v ./filter_bench -impl=2 -quick -working_mem_size_mb=1000 -
    average_keys_per_filter=10000
    Build avg ns/key: 30.5694
    Maximum resident set size (kbytes): 1208152

std::deque impl (after)

    $ /usr/bin/time -v ./filter_bench -impl=2 -quick -new_builder -working_mem_size_mb=1000 -
    average_keys_per_filter=6000000
    Build avg ns/key: 39.0697
    Maximum resident set size (kbytes): 1087196
    $ /usr/bin/time -v ./filter_bench -impl=2 -quick -working_mem_size_mb=1000 -
    average_keys_per_filter=10000
    Build avg ns/key: 30.9348
    Maximum resident set size (kbytes): 1207980

Differential Revision: D19053431

Pulled By: pdillinger

fbshipit-source-id: 2888e748723a19d9ea40403934f13cbb8483430c

Summary:
Fix the test failure.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6178

Differential Revision: D19071208

Pulled By: maysamyabandeh

fbshipit-source-id: 71622832ac93ff2663946c546d9642d5b9e3d194

Summary:
Current implementation holds on to 10% of snapshots for 10x longer, and 1% of snapshots 100x longer.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6171

Test Plan:
```
make -j32 crash_test

Differential Revision: D19038399

Pulled By: maysamyabandeh

fbshipit-source-id: 75da2dbb5c47a0b3f37d299b8719e392b73b42c0

Summary:
We have observed an increase in CPU load caused by frequent calls to
`ColumnFamilyData::InstallSuperVersion` from `DBImpl::TrimMemtableHistory`
when using `max_write_buffer_size_to_maintain` to limit the amount of
memtable history maintained for transaction conflict checking. Part of the issue
is that trimming can potentially be scheduled even if there is no memtable
history. The patch adds a check that fixes this.

See also https://github.com/facebook/rocksdb/pull/6169.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6177

Test Plan:
Compared `perf` output for

```
./db_bench -benchmarks=randomtransaction -optimistic_transaction_db=1 -statistics -stats_interval_seconds=1 -duration=90 -num=500000 --max_write_buffer_size_to_maintain=16000000 --transaction_set_snapshot=1 --threads=32
```

before and after the change. There is a significant reduction for the call chain
`rocksdb::DBImpl::TrimMemtableHistory` -> `rocksdb::ColumnFamilyData::InstallSuperVersion` ->
`rocksdb::ThreadLocalPtr::StaticMeta::Scrape` even without https://github.com/facebook/rocksdb/pull/6169.

Differential Revision: D19057445

Pulled By: ltamasi

fbshipit-source-id: dff81882d7b280e17eda7d9b072a2d4882c50f79

Summary:
Close asserts that there is no unreleased snapshots. For WritePrepared transaction, this means that the background work that holds on a snapshot must be canceled first. Update the stress tests to respect the sequence.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6174

Test Plan:
```
make -j32 crash_test

Differential Revision: D19057322

Pulled By: maysamyabandeh

fbshipit-source-id: c9e9e24f779bbfb0ab72c2717e34576c01bc6362

Summary:
Closes https://github.com/facebook/rocksdb/issues/6118
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6167

Differential Revision: D19053577

Pulled By: pdillinger

fbshipit-source-id: 86aca9a5bec0947a641649b515da17b3cb12bdde

Summary:
Periodic compactions ensure that even SSTs that do not get picked up
otherwise eventually go through compaction; used in conjunction with
BlobDB's garbage collection, they enable BlobDB to reclaim space when
old blob files are used by such straggling SSTs.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6172

Test Plan: Ran `make check` and used the BlobDB mode of `db_bench`.

Differential Revision: D19045045

Pulled By: ltamasi

fbshipit-source-id: 04636ecc4b6cfe8d495bf656faa65d54a5eb1a93

Summary:
The current Env API encompasses both storage/file operations, as well as OS related operations. Most of the APIs return a Status, which does not have enough metadata about an error, such as whether its retry-able or not, scope (i.e fault domain) of the error etc., that may be required in order to properly handle a storage error. The file APIs also do not provide enough control over the IO SLA, such as timeout, prioritization, hinting about placement and redundancy etc.

This PR separates out the file/storage APIs from Env into a new FileSystem class. The APIs are updated to return an IOStatus with metadata about the error, as well as to take an IOOptions structure as input in order to allow more control over the IO.

The user can set both ```options.env``` and ```options.file_system``` to specify that RocksDB should use the former for OS related operations and the latter for storage operations. Internally, a ```CompositeEnvWrapper``` has been introduced that inherits from ```Env``` and redirects individual methods to either an ```Env``` implementation or the ```FileSystem``` as appropriate. When options are sanitized during ```DB::Open```, ```options.env``` is replaced with a newly allocated ```CompositeEnvWrapper``` instance if both env and file_system have been specified. This way, the rest of the RocksDB code can continue to function as before.

This PR also ports PosixEnv to the new API by splitting it into two - PosixEnv and PosixFileSystem. PosixEnv is defined as a sub-class of CompositeEnvWrapper, and threading/time functions are overridden with Posix specific implementations in order to avoid an extra level of indirection.

The ```CompositeEnvWrapper``` translates ```IOStatus``` return code to ```Status```, and sets the severity to ```kSoftError``` if the io_status is retryable. The error handling code in RocksDB can then recover the DB automatically.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5761

Differential Revision: D18868376

Pulled By: anand1976

fbshipit-source-id: 39efe18a162ea746fabac6360ff529baba48486f

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:
We have observed an increase in CPU load caused by frequent calls to
`ColumnFamilyData::InstallSuperVersion` from `DBImpl::TrimMemtableHistory`
when using `max_write_buffer_size_to_maintain` to limit the amount of
memtable history maintained for transaction conflict checking. As it turns out,
this is caused by the code creating and installing a new `SuperVersion` even if
no memtables were actually trimmed. The patch adds a check to avoid this.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6169

Test Plan:
Compared `perf` output for

```
./db_bench -benchmarks=randomtransaction -optimistic_transaction_db=1 -statistics -stats_interval_seconds=1 -duration=90 -num=500000 --max_write_buffer_size_to_maintain=16000000 --transaction_set_snapshot=1 --threads=32
```

before and after the change. With the fix, the call chain `rocksdb::DBImpl::TrimMemtableHistory` ->
`rocksdb::ColumnFamilyData::InstallSuperVersion` -> `rocksdb::ThreadLocalPtr::StaticMeta::Scrape`
no longer registers in the `perf` report.

Differential Revision: D19031509

Pulled By: ltamasi

fbshipit-source-id: 02686fce594e5b50eba0710e4b28a9b808c8aa20

Summary:
fixes https://github.com/facebook/rocksdb/issues/2445
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5916

Differential Revision: D19031236

fbshipit-source-id: bc3107b6b25a01958677d7cb411b1f381aae91c6

Summary:
With WritePrepared transactions configured with two_write_queues, unordered_write will offer the same guarantees as vanilla rocksdb and thus can be enabled in stress tests.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6164

Test Plan:
```
make -j32 crash_test_with_txn

Differential Revision: D18991899

Pulled By: maysamyabandeh

fbshipit-source-id: eece5e96b4169b67d7931e5c0afca88540a113e1

Summary:
The patch adds logic that relocates live blobs from the oldest N non-TTL
blob files as they are encountered during compaction (assuming the BlobDB
configuration option `enable_garbage_collection` is `true`), where N is defined
as the number of immutable non-TTL blob files multiplied by the value of
a new BlobDB configuration option called `garbage_collection_cutoff`.
(The default value of this parameter is 0.25, that is, by default the valid blobs
residing in the oldest 25% of immutable non-TTL blob files are relocated.)
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6121

Test Plan: Added unit test and tested using the BlobDB mode of `db_bench`.

Differential Revision: D18785357

Pulled By: ltamasi

fbshipit-source-id: 8c21c512a18fba777ec28765c88682bb1a5e694e

Summary:
It's easy to cause coredump when closing ColumnFamilyHandle with unreleased iterators, especially iterators release is controlled by java GC when using JNI.

This patch fixed concurrent CF iteration and drop, we let iterators(actually SuperVersion) hold a ColumnFamilyData reference to prevent the CF from being released too early.

fixed https://github.com/facebook/rocksdb/issues/5982
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6147

Differential Revision: D18926378

fbshipit-source-id: 1dff6d068c603d012b81446812368bfee95a5e15

Summary:
Correct javadocs of several RocksDB option classes to not mislead RocksJava users.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6123

Differential Revision: D18989044

Pulled By: pdillinger

fbshipit-source-id: a5ac6a415e5311084b10d973d354e6925788f01e

Summary:
Read keys from a snapshot that a range deletion were added after the snapshot  was created and this range deletion was inside an immutable memtable, we will get wrong key set.
More detail rest in codes.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6062

Differential Revision: D18966785

Pulled By: pdillinger

fbshipit-source-id: 38a60bb1e2d0a1dbfc8ec641617200b6a02b86c3

Summary:
**Summary:**
This PR fixes two unordered_write related issues:
- ingestion job may skip the necessary memtable flush https://github.com/facebook/rocksdb/issues/6026
- compact range may cause memtable is flushed before pending unordered write finished
    1. `CompactRange` triggers memtable flush but doesn't wait for pending-writes
    2.  there are some pending writes but memtable is already flushed
    3.  the memtable related WAL is removed( note that the pending-writes were recorded in that WAL).
    4.  pending-writes write to newer created memtable
    5. there is a restart
    6. missing the previous pending-writes because WAL is removed but they aren't included in SST.

**How to solve:**
- Wait pending memtable writes before ingestion job check memtable key range
- Wait pending memtable writes before flush memtable.
**Note that: `CompactRange` calls `RangesOverlapWithMemtables` too without waiting for pending waits, but I'm not sure whether it affects the correctness.**

**Test Plan:**
make check
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6113

Differential Revision: D18895674

Pulled By: maysamyabandeh

fbshipit-source-id: da22b4476fc7e06c176020e7cc171eb78189ecaf

Summary:
While the instruction of installing "make format" dependencies works on some platforms, it is hard to use for some others. Improve it a little bit.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6162

Test Plan: Run "make format" on an envrionment missing the dependencies and see the instructions printed out

Differential Revision: D18970773

fbshipit-source-id: fd21b31053407cc171a6675f781a556a1c3e8945

Summary:
This change fixes a source issue that caused compile time error which breaks build for many fbcode services in that setup. The size() member function of channel is a const member, so member variables accessed within it are implicitly const as well. This caused error when clang fails to resolve to a constructor that takes std::mutex because the suitable constructor got rejected due to loss of constness for its argument. The fix is to add mutable modifier to the lock_ member of channel.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6161

Differential Revision: D18967685

Pulled By: maysamyabandeh

fbshipit-source-id: 698b6a5153c3c92eeacb842c467aa28cc350d432

Summary:
As requested in https://github.com/facebook/rocksdb/issues/6127
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6152

Differential Revision: D18955608

Pulled By: pdillinger

fbshipit-source-id: 3e1367d944e44d5f1675a422f7dd2451c86feb6f

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6156

Test Plan: Extended unit tests.

Differential Revision: D18943867

Pulled By: ltamasi

fbshipit-source-id: b3669d2dd6af08e987ad1a59d6712ae2514da0b1

Summary:
Currently the default txn write policy in crash tests is WRITE_PREPARED. The patch randomly picks the write policy at the start of the crash test.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6158

Test Plan:
```
make -j32 crash_test_with_txn
```

Differential Revision: D18946307

Pulled By: maysamyabandeh

fbshipit-source-id: f77d7a94f99a08791ef9626da153d284bf521950

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6157

Test Plan: make check

Differential Revision: D18944259

Pulled By: ltamasi

fbshipit-source-id: 7fb29447b52d801215bd6ab811e229a7fa2c763d

Summary:
Start daily crash tests with use_txn flag.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6155

Differential Revision: D18943630

Pulled By: maysamyabandeh

fbshipit-source-id: eea99a6ffd5f57fb9651f6ca7dab8fbf70379c87

Summary:
This test was recently updated but failed to account for Bloom
schema variance by CACHE_LINE_SIZE. (Since CACHE_LINE_SIZE is not
defined in our C code, the test now simply allows a valid result for any
CACHE_LINE_SIZE, not just the current one.)

Unblock https://github.com/facebook/rocksdb/issues/5932
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6153

Test Plan:
ran unit test with builds TEST_CACHE_LINE_SIZE=128, =256, and
unset (64 on Intel)

Differential Revision: D18936015

Pulled By: pdillinger

fbshipit-source-id: e5e3852f95283d34d624632c1ae8d3adb2f2662c

Summary:
`curr.level` is `c->inputs_` index, not real level.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6067

Differential Revision: D18935726

fbshipit-source-id: 4354e6e9cd900ca56c96e9d770f0ab6634e45daf

Summary: Pull Request resolved: https://github.com/facebook/rocksdb/pull/6116

Differential Revision: D18935622

fbshipit-source-id: 59f7a7bc9f0116ae6354ea217896622a34329d3c

Summary:
`low_pri_write_rate_limiter_` is not being used. Removing. `WriteController` has an internal low_pri rate limiter which is the real rate limiter for low-pri writes.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6068

Test Plan: make

Differential Revision: D18664120

fbshipit-source-id: dfe3e4de033cf3522b67781b383aad7d0936034c

Summary:
Adds example to show the difference of reading from snapshot and from the latest state.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6059

Test Plan: cd examples && make transaction_example && ./transaction_example

Differential Revision: D18797616

fbshipit-source-id: f17a2cb12187092ea243159e6ccf55790859e0c0

Summary:
Add SyncWAL to db_stress. Specify with `-sync_wal_one_in=N` so that it will be
called once every N operations on average.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6149

Test Plan:
```
$make db_stress
$./db_stress -sync_wal_one_in=100 -ops_per_thread=100000
```

Differential Revision: D18922529

Pulled By: riversand963

fbshipit-source-id: 4c0b8cb8fa21852722cffd957deddf688f12ea56

Summary:
CancelAllBackgroundWork() and Close() are frequently used features but we don't cover it in stress test. Simply execute them before closing the DB with 1/2 chance.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6141

Test Plan: Run "db_stress".

Differential Revision: D18900861

fbshipit-source-id: 49b46ccfae120d0f9de3e0543b82fb6d715949d0

Summary:
This is required to compile on Windows with Visual Studio 2015, which is used for creating the RocksJava releases.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5446

Differential Revision: D18924811

fbshipit-source-id: a183a62e79a2af5aaf59cd08235458a172fe7dcb

Summary:
Worker thread will occasionally call PauseBackgroundWork(),
briefly sleep (to avoid stalling itself) and then call
ContinueBackgroundWork().
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6148

Test Plan:
some running of 'make blackbox_crash_test' with temporary
printf output to confirm code occasionally reached.

Differential Revision: D18913886

Pulled By: pdillinger

fbshipit-source-id: ae9356a803390929f3165dfb6a00194692ba92be

Summary:
Add an option to explicitly disable building shared versions of the
RocksDB libraries.  The shared libraries cannot be built in cases where
some dependencies are only available as static libraries.  This allows
still building RocksDB in these situations.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6122

Differential Revision: D18920740

fbshipit-source-id: d24f66d93c68a1e65635e6e0b663bae62c903bca

Summary:
For more portability, switch from readdir to Env::GetChildren() in ldb's
manifest_dump subcommand.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6139

Test Plan:
```
$make check
```
Manually check ldb command.

Differential Revision: D18898197

Pulled By: riversand963

fbshipit-source-id: 92afca379e9fbe78ab70b2eb40d127daad8df5e2

Summary:
Right now, in db_stress, compact range is simply executed without any immediate data validation. Add a simply validation which compares hash for all keys within the compact range to stay the same against the same snapshot before and after the compaction.

Also, randomly tune most knobs of CompactRangeOptions.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6140

Test Plan: Run db_stress with "--compact_range_one_in=2000 --compact_range_width=100000000" for a while. Manually ingest some hacky code and observe the error path.

Differential Revision: D18900230

fbshipit-source-id: d96e75bc8c38dd5ec702571ffe7cf5f4ea93ee10

Summary:
Error message when running `make` on Mac OS with master branch (v6.6.0):
```
$ make
$DEBUG_LEVEL is 1
Makefile:168: Warning: Compiling in debug mode. Don't use the resulting binary in production
third-party/folly/folly/synchronization/WaitOptions.cpp:6:10: fatal error: 'folly/synchronization/WaitOptions.h' file not found
#include <folly/synchronization/WaitOptions.h>
         ^
1 error generated.
third-party/folly/folly/synchronization/ParkingLot.cpp:6:10: fatal error: 'folly/synchronization/ParkingLot.h' file not found
#include <folly/synchronization/ParkingLot.h>
         ^
1 error generated.
third-party/folly/folly/synchronization/DistributedMutex.cpp:6:10: fatal error: 'folly/synchronization/DistributedMutex.h' file not found
#include <folly/synchronization/DistributedMutex.h>
         ^
1 error generated.
third-party/folly/folly/synchronization/AtomicNotification.cpp:6:10: fatal error: 'folly/synchronization/AtomicNotification.h' file not found
#include <folly/synchronization/AtomicNotification.h>
         ^
1 error generated.
third-party/folly/folly/detail/Futex.cpp:6:10: fatal error: 'folly/detail/Futex.h' file not found
#include <folly/detail/Futex.h>
         ^
1 error generated.
  GEN      util/build_version.cc
$DEBUG_LEVEL is 1
Makefile:168: Warning: Compiling in debug mode. Don't use the resulting binary in production
third-party/folly/folly/synchronization/WaitOptions.cpp:6:10: fatal error: 'folly/synchronization/WaitOptions.h' file not found
#include <folly/synchronization/WaitOptions.h>
         ^
1 error generated.
third-party/folly/folly/synchronization/ParkingLot.cpp:6:10: fatal error: 'folly/synchronization/ParkingLot.h' file not found
#include <folly/synchronization/ParkingLot.h>
         ^
1 error generated.
third-party/folly/folly/synchronization/DistributedMutex.cpp:6:10: fatal error: 'folly/synchronization/DistributedMutex.h' file not found
#include <folly/synchronization/DistributedMutex.h>
         ^
1 error generated.
third-party/folly/folly/synchronization/AtomicNotification.cpp:6:10: fatal error: 'folly/synchronization/AtomicNotification.h' file not found
#include <folly/synchronization/AtomicNotification.h>
         ^
1 error generated.
third-party/folly/folly/detail/Futex.cpp:6:10: fatal error: 'folly/detail/Futex.h' file not found
#include <folly/detail/Futex.h>
```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6145

Differential Revision: D18910812

fbshipit-source-id: 5a4475466c2d0601657831a0b48d34316b2f0816

Summary:
Especially with non-integral bits/key now supported,
db_crashtest should vary the bloom_bits configuration. The probabilities
look like this:

1/2 chance of a uniform int from 0 to 19. This includes overall 1/40
chance of 0 which disables the bloom filter.

1/2 chance of a float from a lognormal distribution with a median of 10.
This always produces positive values but with a decent chance of < 1
(overall ~1/40) or > 100 (overall ~1/40), the enforced/coerced
implementation limits.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/6103

Test Plan:
start 'make blackbox_crash_test' several times and look at
configuration output

Differential Revision: D18734877

Pulled By: pdillinger

fbshipit-source-id: 4a38cb057d3b3fc1327f93199f65b9a9ffbd7316