Summary:
Right now, deleting blob files is not rate limited, even if SstFileManger is specified.
On the other hand, rate limiting blob deletion is not supported. With this change, Blob file
deletion will go through SstFileManager too.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4904
Differential Revision: D13772545
Pulled By: siying
fbshipit-source-id: bd1b1d0beb26d5167385e00b7ecb8b94b879de84
Summary:
Remove unused blob WAL filter so that users are not confused.
I was initially under the impression that we have WAL Filter support in BlobDB.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4896
Differential Revision: D13725709
Pulled By: sagar0
fbshipit-source-id: f997d7546e138a474036e88b957907cc714327f1
Summary:
This is essentially a re-submission of #4251 with a few improvements:
- Split `CompressionDict` into two separate classes: `CompressionDict` and `UncompressionDict`
- Eliminated `Init` functions. Instead do all initialization work in constructors.
- Added test case for parallel DB open, which is the scenario where #4251 failed under TSAN.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4849
Differential Revision: D13606039
Pulled By: ajkr
fbshipit-source-id: 08c236059798c710db9cbf545fce0f371232d447
Summary:
Remove `garbage_collection_deletion_size_threshold` as it is not used anywhere.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4888
Differential Revision: D13685982
Pulled By: sagar0
fbshipit-source-id: e08d3017b9a0c8fa99bc332b595ee4ed9db70c87
Summary:
- Corrected a comment asserting that the values "smaller" than a min_blob_size will be inlined in the base db.
- Also fixed the type of ttl_range_secs while dumping blobdb options.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4887
Differential Revision: D13680163
Pulled By: sagar0
fbshipit-source-id: 306c8cf2daa52210ffc334a6924ef44ffdedf887
Summary:
As pointed out in #4059, we miss use string as buffer for file read. Changing to use char array instead.
Closing #4059
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4662
Differential Revision: D13012998
Pulled By: yiwu-arbug
fbshipit-source-id: 41234ba17c0bccea65bd647e362a0e979152bd1e
Summary:
Ran the following commands to recursively change all the files under RocksDB:
```
find . -type f -name "*.cc" -exec sed -i 's/ unique_ptr/ std::unique_ptr/g' {} +
find . -type f -name "*.cc" -exec sed -i 's/<unique_ptr/<std::unique_ptr/g' {} +
find . -type f -name "*.cc" -exec sed -i 's/ shared_ptr/ std::shared_ptr/g' {} +
find . -type f -name "*.cc" -exec sed -i 's/<shared_ptr/<std::shared_ptr/g' {} +
```
Running `make format` updated some formatting on the files touched.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4638
Differential Revision: D12934992
Pulled By: sagar0
fbshipit-source-id: 45a15d23c230cdd64c08f9c0243e5183934338a8
Summary:
Ensure delete[] and not delete is called on buffer_, as it is reset with new char[buffer_size_].
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4647
Differential Revision: D12961327
Pulled By: ajkr
fbshipit-source-id: c1af373b98359edfdc291caebe4e0acdfb8afdd8
Summary:
A fix similar to #4410 but on the write path. On IO error on `SelectBlobFile()` we didn't return error code properly, but simply a nullptr of `BlobFile`. The `AppendBlob()` method didn't have null check for the pointer and caused crash. The fix make sure we properly return error code in this case.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4580
Differential Revision: D10513849
Pulled By: yiwu-arbug
fbshipit-source-id: 80bca920d1d7a3541149de981015ad83e0aa14b5
Summary:
- Fix DBImpl API race condition
The timeline of execution flow is as follow:
```
timeline user_thread1 user_thread2
t1 | cfh = GetColumnFamilyHandleUnlocked(0)
t2 | id1 = cfh->GetID()
t3 | GetColumnFamilyHandleUnlocked(1)
t4 | id2 = cfh->GetID()
V
```
The original implementation return a pointer to a stateful variable, so that the return `ColumnFamilyHandle` will be changed when another thread calls `GetColumnFamilyHandleUnlocked` with different `column family id`
- Expose ColumnFamily ID to compaction event listener
- Fix the return status of `DBImpl::GetLatestSequenceForKey`
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4391
Differential Revision: D10221243
Pulled By: yiwu-arbug
fbshipit-source-id: dec60ee9ff0c8261a2f2413a8506ec1063991993
Summary:
Fix IO error on read not being handle and crashing the DB. With the fix we properly return the error.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4410
Differential Revision: D9979246
Pulled By: yiwu-arbug
fbshipit-source-id: 111a85675067a29c03cb60e9a34103f4ff636694
Summary:
Reverting is needed to unblock a user building against master, who is blocked for multiple days due to a thread-safety issue in `GetEmptyDict`. We haven't been able to fix it quickly, so reverting.
Simply ran `git revert 6c40806e51a89386d2b066fddf73d3fd03a36f65`. There were no merge conflicts.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4347
Differential Revision: D9668365
Pulled By: ajkr
fbshipit-source-id: 0c56334f0a23cf5ee0233d4e4679eae6709739cd
Summary:
As you know, almost all compilers support "pragma once" keyword instead of using include guards. To be keep consistency between header files, all header files are edited.
Besides this, try to fix some warnings about loss of data.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4339
Differential Revision: D9654990
Pulled By: ajkr
fbshipit-source-id: c2cf3d2d03a599847684bed81378c401920ca848
Summary:
`GetLiveFiles` and `GetLiveFilesMetadata` should return path relative to db path.
It is a separate issue when `path_relative` is false how can we return relative path. But `DBImpl::GetLiveFiles` don't handle it as well when there are multiple `db_paths`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4326
Differential Revision: D9545904
Pulled By: yiwu-arbug
fbshipit-source-id: 6762d879fcb561df2b612e6fdfb4a6b51db03f5d
Summary:
When reading an expired key using `Get(..., std::string* value)` API, BlobDB first read the index entry and decode expiration from it. In this case, although BlobDB reset the PinnableSlice, the index entry is stored in user provided string `value`. The value will be returned as a garbage value, despite status being NotFound. Fixing it by use a different PinnableSlice to read the index entry.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4321
Differential Revision: D9519042
Pulled By: yiwu-arbug
fbshipit-source-id: f054c951a1fa98265228be94f931904ed7056677
Summary:
`DB::DiableFileDeletions` and `DB::EnableFileDeletions` are used for applications to stop RocksDB background jobs to delete files while they are doing replication. Implement these methods for BlobDB. `DeleteObsolteFiles` now needs to check `disable_file_deletions_` before starting, and will hold `delete_file_mutex_` the whole time while it is running. `DisableFileDeletions` needs to wait on `delete_file_mutex_` for running `DeleteObsolteFiles` job and set `disable_file_deletions_` flag.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4314
Differential Revision: D9501373
Pulled By: yiwu-arbug
fbshipit-source-id: 81064c1228f1724eff46da22b50ff765b16292cd
Summary:
In RocksDB, for a given SST file, all data blocks are compressed with the same dictionary. When we compress a block using the dictionary's raw bytes, the compression library first has to digest the dictionary to get it into a usable form. This digestion work is redundant and ideally should be done once per file.
ZSTD offers APIs for the caller to create and reuse a digested dictionary object (`ZSTD_CDict`). In this PR, we call `ZSTD_createCDict` once per file to digest the raw bytes. Then we use `ZSTD_compress_usingCDict` to compress each data block using the pre-digested dictionary. Once the file's created `ZSTD_freeCDict` releases the resources held by the digested dictionary.
There are a couple other changes included in this PR:
- Changed the parameter object for (un)compression functions from `CompressionContext`/`UncompressionContext` to `CompressionInfo`/`UncompressionInfo`. This avoids the previous pattern, where `CompressionContext`/`UncompressionContext` had to be mutated before calling a (un)compression function depending on whether dictionary should be used. I felt that mutation was error-prone so eliminated it.
- Added support for digested uncompression dictionaries (`ZSTD_DDict`) as well. However, this PR does not support reusing them across uncompression calls for the same file. That work is deferred to a later PR when we will store the `ZSTD_DDict` objects in block cache.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4251
Differential Revision: D9257078
Pulled By: ajkr
fbshipit-source-id: 21b8cb6bbdd48e459f1c62343780ab66c0a64438
Summary:
We want to sample the file I/O issued by RocksDB and report the function calls. This requires us to include the file paths otherwise it's hard to tell what has been going on.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4039
Differential Revision: D8670178
Pulled By: riversand963
fbshipit-source-id: 97ee806d1c583a2983e28e213ee764dc6ac28f7a
Summary:
Fix expired file not being evicted from the DB. We have a background task (previously called `CheckSeqFiles` and I rename it to `EvictExpiredFiles`) to scan and remove expired files, but it only close the files, not marking them as expired.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4294
Differential Revision: D9415984
Pulled By: yiwu-arbug
fbshipit-source-id: eff7bf0331c52a7ccdb02318602bff7f64f3ef3d
Summary:
Right now, `ldb idump` may have memory out of control if there is a big range of tombstones. Add an option to cut maxinum number of keys in GetAllKeyVersions(), and push down --max_num_ikeys from ldb.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4271
Differential Revision: D9369149
Pulled By: siying
fbshipit-source-id: 7cbb797b7d2fa16573495a7e84937456d3ff25bf
Summary:
Add API to allow fetching expiration of a key with `Get()`.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4227
Differential Revision: D9169897
Pulled By: yiwu-arbug
fbshipit-source-id: 2a6f216c493dc75731ddcef1daa689b517fab31b
Summary:
There are two issues with `VisibleToActiveSnapshot`:
1. If there are no snapshots, `oldest_snapshot` will be 0 and `VisibleToActiveSnapshot` will always return true. Since the method is used to decide whether it is safe to delete obsolete files, obsolete file won't be able to delete in this case.
2. The `auto` keyword of `auto snapshots = db_impl_->snapshots()` translate to a copy of `const SnapshotList` instead of a reference. Since copy constructor of `SnapshotList` is not defined, using the copy may yield unexpected result.
Issue 2 actually hide issue 1 from being catch by tests. During test `snapshots.empty()` can return false while it should actually be empty, and `snapshots.oldest()` return an invalid address, making `oldest_snapshot` being some random large number.
The issue was originally reported by BlobDB early adopter at Kuaishou.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4236
Differential Revision: D9188706
Pulled By: yiwu-arbug
fbshipit-source-id: a0f2624b927cf9bf28c1bb534784fee5d106f5ea
Summary:
Cleanup TTLExtractor interface. The original purpose of it is to allow our users keep using existing `Write()` interface but allow it to accept TTL via `TTLExtractor`. However the interface is confusing. Will replace it with something like `WriteWithTTL(batch, ttl)` in the future.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4229
Differential Revision: D9174390
Pulled By: yiwu-arbug
fbshipit-source-id: 68201703d784408b851336ab4dd9b84188245b2d
Summary:
The patch makes sure that two parallel test threads will operate on different db paths. This enables using open source tools such as gtest-parallel to run the tests of a file in parallel.
Example: ``` ~/gtest-parallel/gtest-parallel ./table_test```
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4135
Differential Revision: D8846653
Pulled By: maysamyabandeh
fbshipit-source-id: 799bad1abb260e3d346bcb680d2ae207a852ba84
Summary:
Previously with is_fifo=true we only evict TTL file. Changing it to also evict non-TTL files from oldest to newest, after exhausted TTL files.
Closes https://github.com/facebook/rocksdb/pull/4049
Differential Revision: D8604597
Pulled By: yiwu-arbug
fbshipit-source-id: bc4209ee27c1528ce4b72833e6f1e1bff80082c1
Summary:
Enable readahead for blob DB garbage collection, which should improve GC performance a little bit.
Closes https://github.com/facebook/rocksdb/pull/3648
Differential Revision: D7383791
Pulled By: yiwu-arbug
fbshipit-source-id: 642b3327f7105eca85986d3fb2d8f960a3d83cf1
Summary:
We potentially need this information for tracing, profiling and diagnosis.
Closes https://github.com/facebook/rocksdb/pull/4026
Differential Revision: D8555214
Pulled By: riversand963
fbshipit-source-id: 4263e06c00b6d5410b46aa46eb4e358ff2161dd2
Summary:
PR https://github.com/facebook/rocksdb/pull/3838 made some changes that triggers lint warnings.
Run `make format` to fix formatting as suggested by siying .
Also piggyback two changes:
1) fix singleton destruction order for windows and posix env
2) fix two clang warnings
Closes https://github.com/facebook/rocksdb/pull/3954
Differential Revision: D8272041
Pulled By: miasantreble
fbshipit-source-id: 7c4fd12bd17aac13534520de0c733328aa3c6c9f
Summary:
Windows does not have LD_PRELOAD mechanism to override all memory allocation functions and ZSTD makes use of C-tuntime calloc. During flushes and compactions default system allocator fragments and the system slows down considerably.
For builds with jemalloc we employ an advanced ZSTD context creation API that re-directs memory allocation to jemalloc. To reduce the cost of context creation on each block we cache ZSTD context within the block based table builder while a new SST file is being built, this will help all platform builds including those w/o jemalloc. This avoids system allocator fragmentation and improves the performance.
The change does not address random reads and currently on Windows reads with ZSTD regress as compared with SNAPPY compression.
Closes https://github.com/facebook/rocksdb/pull/3838
Differential Revision: D8229794
Pulled By: miasantreble
fbshipit-source-id: 719b622ab7bf4109819bc44f45ec66f0dd3ee80d
Summary:
Before this PR, Iterator/InternalIterator may simultaneously have non-ok status() and Valid() = true. That state means that the last operation failed, but the iterator is nevertheless positioned on some unspecified record. Likely intended uses of that are:
* If some sst files are corrupted, a normal iterator can be used to read the data from files that are not corrupted.
* When using read_tier = kBlockCacheTier, read the data that's in block cache, skipping over the data that is not.
However, this behavior wasn't documented well (and until recently the wiki on github had misleading incorrect information). In the code there's a lot of confusion about the relationship between status() and Valid(), and about whether Seek()/SeekToLast()/etc reset the status or not. There were a number of bugs caused by this confusion, both inside rocksdb and in the code that uses rocksdb (including ours).
This PR changes the convention to:
* If status() is not ok, Valid() always returns false.
* Any seek operation resets status. (Before the PR, it depended on iterator type and on particular error.)
This does sacrifice the two use cases listed above, but siying said it's ok.
Overview of the changes:
* A commit that adds missing status checks in MergingIterator. This fixes a bug that actually affects us, and we need it fixed. `DBIteratorTest.NonBlockingIterationBugRepro` explains the scenario.
* Changes to lots of iterator types to make all of them conform to the new convention. Some bug fixes along the way. By far the biggest changes are in DBIter, which is a big messy piece of code; I tried to make it less big and messy but mostly failed.
* A stress-test for DBIter, to gain some confidence that I didn't break it. It does a few million random operations on the iterator, while occasionally modifying the underlying data (like ForwardIterator does) and occasionally returning non-ok status from internal iterator.
To find the iterator types that needed changes I searched for "public .*Iterator" in the code. Here's an overview of all 27 iterator types:
Iterators that didn't need changes:
* status() is always ok(), or Valid() is always false: MemTableIterator, ModelIter, TestIterator, KVIter (2 classes with this name anonymous namespaces), LoggingForwardVectorIterator, VectorIterator, MockTableIterator, EmptyIterator, EmptyInternalIterator.
* Thin wrappers that always pass through Valid() and status(): ArenaWrappedDBIter, TtlIterator, InternalIteratorFromIterator.
Iterators with changes (see inline comments for details):
* DBIter - an overhaul:
- It used to silently skip corrupted keys (`FindParseableKey()`), which seems dangerous. This PR makes it just stop immediately after encountering a corrupted key, just like it would for other kinds of corruption. Let me know if there was actually some deeper meaning in this behavior and I should put it back.
- It had a few code paths silently discarding subiterator's status. The stress test caught a few.
- The backwards iteration code path was expecting the internal iterator's set of keys to be immutable. It's probably always true in practice at the moment, since ForwardIterator doesn't support backwards iteration, but this PR fixes it anyway. See added DBIteratorTest.ReverseToForwardBug for an example.
- Some parts of backwards iteration code path even did things like `assert(iter_->Valid())` after a seek, which is never a safe assumption.
- It used to not reset status on seek for some types of errors.
- Some simplifications and better comments.
- Some things got more complicated from the added error handling. I'm open to ideas for how to make it nicer.
* MergingIterator - check status after every operation on every subiterator, and in some places assert that valid subiterators have ok status.
* ForwardIterator - changed to the new convention, also slightly simplified.
* ForwardLevelIterator - fixed some bugs and simplified.
* LevelIterator - simplified.
* TwoLevelIterator - changed to the new convention. Also fixed a bug that would make SeekForPrev() sometimes silently ignore errors from first_level_iter_.
* BlockBasedTableIterator - minor changes.
* BlockIter - replaced `SetStatus()` with `Invalidate()` to make sure non-ok BlockIter is always invalid.
* PlainTableIterator - some seeks used to not reset status.
* CuckooTableIterator - tiny code cleanup.
* ManagedIterator - fixed some bugs.
* BaseDeltaIterator - changed to the new convention and fixed a bug.
* BlobDBIterator - seeks used to not reset status.
* KeyConvertingIterator - some small change.
Closes https://github.com/facebook/rocksdb/pull/3810
Differential Revision: D7888019
Pulled By: al13n321
fbshipit-source-id: 4aaf6d3421c545d16722a815b2fa2e7912bc851d
Summary:
this PR fixes a few failed contbuild:
1. ASAN memory leak in Block::NewIterator (table/block.cc:429). the proper destruction of first_level_iter_ and second_level_iter_ of two_level_iterator.cc is missing from the code after the refactoring in https://github.com/facebook/rocksdb/pull/3406
2. various unused param errors introduced by https://github.com/facebook/rocksdb/pull/3662
3. updated comment for `ForceReleaseCachedEntry` to emphasize the use of `force_erase` flag.
Closes https://github.com/facebook/rocksdb/pull/3718
Reviewed By: maysamyabandeh
Differential Revision: D7621192
Pulled By: miasantreble
fbshipit-source-id: 476c94264083a0730ded957c29de7807e4f5b146
Summary:
Make blob_dump tool able to show uncompressed values if the blob file is compressed. Also show total compressed vs. raw size at the end if --show_summary is provided.
Closes https://github.com/facebook/rocksdb/pull/3633
Differential Revision: D7348926
Pulled By: yiwu-arbug
fbshipit-source-id: ca709cb4ed5cf6a550ff2987df8033df81516f8e
Summary:
* Fix BlobDBImpl::GCFileAndUpdateLSM doesn't close the new file, and the new file will not be able to be garbage collected later.
* Fix BlobDBImpl::GCFileAndUpdateLSM doesn't copy over metadata from old file to new file.
Closes https://github.com/facebook/rocksdb/pull/3639
Differential Revision: D7355092
Pulled By: yiwu-arbug
fbshipit-source-id: 4fa3594ac5ce376bed1af04a545c532cfc0088c4
Summary:
Improving blob db FIFO eviction with the following changes,
* Change blob_dir_size to max_db_size. Take into account SST file size when computing DB size.
* FIFO now only take into account live sst files and live blob files. It is normal for disk usage to go over max_db_size because there are obsolete sst files and blob files pending deletion.
* FIFO eviction now also evict TTL blob files that's still open. It doesn't evict non-TTL blob files.
* If FIFO is triggered, it will pass an expiration and the current sequence number to compaction filter. Compaction filter will then filter inlined keys to evict those with an earlier expiration and smaller sequence number. So call LSM FIFO.
* Compaction filter also filter those blob indexes where corresponding blob file is gone.
* Add an event listener to listen compaction/flush event and update sst file size.
* Implement DB::Close() to make sure base db, as well as event listener and compaction filter, destruct before blob db.
* More blob db statistics around FIFO.
* Fix some locking issue when accessing a blob file.
Closes https://github.com/facebook/rocksdb/pull/3556
Differential Revision: D7139328
Pulled By: yiwu-arbug
fbshipit-source-id: ea5edb07b33dfceacb2682f4789bea61de28bbfa
Summary:
Red diff to remove existing implementation of garbage collection. The current approach is reference counting kind of approach and require a lot of effort to get the size counter right on compaction and deletion. I'm going to go with a simple mark-sweep kind of approach and will send another PR for that.
CompactionEventListener was added solely for blob db and it adds complexity and overhead to compaction iterator. Removing it as well.
Closes https://github.com/facebook/rocksdb/pull/3551
Differential Revision: D7130190
Pulled By: yiwu-arbug
fbshipit-source-id: c3a375ad2639a3f6ed179df6eda602372cc5b8df
Summary:
When blob_files is empty, std::min_element will return blobfiles.end(), which cannot be dereference. Fixing it.
Closes https://github.com/facebook/rocksdb/pull/3387
Differential Revision: D6764927
Pulled By: yiwu-arbug
fbshipit-source-id: 86f78700132be95760d35ac63480dfd3a8bbe17a
Summary:
Previously on a blob db read, we are making a read of the blob value, and then make another read to get CRC checksum. I'm combining the two read into one.
readrandom db_bench with 1G database with base db size of 13M, value size 1k:
`./db_bench --db=/home/yiwu/tmp/db_bench --use_blob_db --value_size=1024 --num=1000000 --benchmarks=readrandom --use_existing_db --cache_size=32000000`
master: throughput 234MB/s, get micros p50 5.984 p95 9.998 p99 20.817 p100 787
this PR: throughput 261MB/s, get micros p50 5.157 p95 9.928 p99 20.724 p100 190
Closes https://github.com/facebook/rocksdb/pull/3301
Differential Revision: D6615950
Pulled By: yiwu-arbug
fbshipit-source-id: 052410c6d8539ec0cc305d53793bbc8f3616baa3
Summary:
We dump blob db options on blob db open, but it was removed by mistake in #3246. Adding it back.
Closes https://github.com/facebook/rocksdb/pull/3298
Differential Revision: D6607177
Pulled By: yiwu-arbug
fbshipit-source-id: 2a4aacbfa52fd8f1878dc9e1fbb95fe48faf80c0
Summary:
Previously, if blob_db_options.bytes_per_sync, there is a background job to call fsync() for every bytes_per_sync bytes written to a blob file. With the change we simply pass bytes_per_sync as env_options_ to blob files so that sync_file_range() will be used instead.
Closes https://github.com/facebook/rocksdb/pull/3297
Differential Revision: D6606994
Pulled By: yiwu-arbug
fbshipit-source-id: 452424be52e32ba92f5ea603b564e9b88929af47
Summary:
Previously we store sequence number range of each blob files, and use the sequence number range to check if the file can be possibly visible by a snapshot. But it adds complexity to the code, since the sequence number is only available after a write. (The current implementation get sequence number by calling GetLatestSequenceNumber(), which is wrong.) With the patch, we are not storing sequence number range, and check if snapshot_sequence < obsolete_sequence to decide if the file is visible by a snapshot (previously we check if first_sequence <= snapshot_sequence < obsolete_sequence).
Closes https://github.com/facebook/rocksdb/pull/3274
Differential Revision: D6571497
Pulled By: yiwu-arbug
fbshipit-source-id: ca06479dc1fcd8782f6525b62b7762cd47d61909
Summary:
Refactor BlobDB open logic. List of changes:
Major:
* On reopen, mark blob files found as immutable, do not use them for writing new keys.
* Not to scan the whole file to find file footer. Instead just seek to the end of the file and try to read footer.
Minor:
* Move most of the real logic from blob_db.cc to blob_db_impl.cc.
* Not to hold shared_ptr of event listeners in global maps in blob_db.cc
* Some changes to BlobFile interface.
* Improve logging and error handling.
Closes https://github.com/facebook/rocksdb/pull/3246
Differential Revision: D6526147
Pulled By: yiwu-arbug
fbshipit-source-id: 9dc4cdd63359a2f9b696af817086949da8d06952
