Commit Graph

271 Commits

Author SHA1 Message Date
Jay Zhuang
d3a2f284d9 Add Temperature info in NewSequentialFile() (#9499)
Summary:
Add Temperature hints information from RocksDB in API
`NewSequentialFile()`. backup and checkpoint operations need to open the
source files with `NewSequentialFile()`, which will have the temperature
hints. Other operations are not covered.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9499

Test Plan: Added unittest

Reviewed By: pdillinger

Differential Revision: D34006115

Pulled By: jay-zhuang

fbshipit-source-id: 568b34602b76520e53128672bd07e9d886786a2f
2022-02-18 18:23:07 -08:00
Peter Dillinger
78aee6fedc Remove obsolete backupable_db.h, utility_db.h (#9438)
Summary:
This also removes the obsolete names BackupableDBOptions
and UtilityDB. API users must now use BackupEngineOptions and
DBWithTTL::Open. In C API, `rocksdb_backupable_db_*` is replaced
`rocksdb_backup_engine_*`. Similar renaming in Java API.

In reference to https://github.com/facebook/rocksdb/issues/9389

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9438

Test Plan: CI

Reviewed By: mrambacher

Differential Revision: D33780269

Pulled By: pdillinger

fbshipit-source-id: 4a6cfc5c1b4c78bcad790b9d3dd13c5fdf4a1fac
2022-01-27 15:45:30 -08:00
mrambacher
fe31dc53ca Make the Env class Customizable (#9293)
Summary:
Allows the Env to have options (Configurable) and loads like other Customizable classes.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9293

Reviewed By: pdillinger, zhichao-cao

Differential Revision: D33181591

Pulled By: mrambacher

fbshipit-source-id: 55e823886c654d214eda9eedd45ccdc54dac14d7
2022-01-04 16:45:49 -08:00
Andrew Kryczka
538d2365e9 Fix race condition in BackupEngineTest.ChangeManifestDuringBackupCreation (#9327)
Summary:
The failure looked like this:

```
utilities/backupable/backupable_db_test.cc:3161: Failure
Value of: db_chroot_env_->FileExists(prev_manifest_path).IsNotFound()
  Actual: false
Expected: true
```

The failure could be coerced consistently with the following patch:

```
 diff --git a/db/db_impl/db_impl_compaction_flush.cc b/db/db_impl/db_impl_compaction_flush.cc
index 80410f671..637636791 100644
 --- a/db/db_impl/db_impl_compaction_flush.cc
+++ b/db/db_impl/db_impl_compaction_flush.cc
@@ -2772,6 +2772,8 @@ void DBImpl::BackgroundCallFlush(Env::Priority thread_pri) {
     if (job_context.HaveSomethingToClean() ||
         job_context.HaveSomethingToDelete() || !log_buffer.IsEmpty()) {
       mutex_.Unlock();
+      bg_cv_.SignalAll();
+      sleep(1);
       TEST_SYNC_POINT("DBImpl::BackgroundCallFlush:FilesFound");
       // Have to flush the info logs before bg_flush_scheduled_--
       // because if bg_flush_scheduled_ becomes 0 and the lock is
```

The cause was a familiar problem, which is manual flush/compaction may
return before files they obsoleted are removed. The solution is just to
wait for "scheduled" work to complete, which includes all phases
including cleanup.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9327

Test Plan:
after this PR, even the above patch to coerce the bug cannot
cause the test to fail.

Reviewed By: riversand963

Differential Revision: D33252208

Pulled By: ajkr

fbshipit-source-id: 720a7eaca58c7247d221911fffe3d5e1dbf581e9
2021-12-22 21:59:53 -08:00
Peter Dillinger
0050a73a4f New stable, fixed-length cache keys (#9126)
Summary:
This change standardizes on a new 16-byte cache key format for
block cache (incl compressed and secondary) and persistent cache (but
not table cache and row cache).

The goal is a really fast cache key with practically ideal stability and
uniqueness properties without external dependencies (e.g. from FileSystem).
A fixed key size of 16 bytes should enable future optimizations to the
concurrent hash table for block cache, which is a heavy CPU user /
bottleneck, but there appears to be measurable performance improvement
even with no changes to LRUCache.

This change replaces a lot of disjointed and ugly code handling cache
keys with calls to a simple, clean new internal API (cache_key.h).
(Preserving the old cache key logic under an option would be very ugly
and likely negate the performance gain of the new approach. Complete
replacement carries some inherent risk, but I think that's acceptable
with sufficient analysis and testing.)

The scheme for encoding new cache keys is complicated but explained
in cache_key.cc.

Also: EndianSwapValue is moved to math.h to be next to other bit
operations. (Explains some new include "math.h".) ReverseBits operation
added and unit tests added to hash_test for both.

Fixes https://github.com/facebook/rocksdb/issues/7405 (presuming a root cause)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9126

Test Plan:
### Basic correctness
Several tests needed updates to work with the new functionality, mostly
because we are no longer relying on filesystem for stable cache keys
so table builders & readers need more context info to agree on cache
keys. This functionality is so core, a huge number of existing tests
exercise the cache key functionality.

### Performance
Create db with
`TEST_TMPDIR=/dev/shm ./db_bench -bloom_bits=10 -benchmarks=fillrandom -num=3000000 -partition_index_and_filters`
And test performance with
`TEST_TMPDIR=/dev/shm ./db_bench -readonly -use_existing_db -bloom_bits=10 -benchmarks=readrandom -num=3000000 -duration=30 -cache_index_and_filter_blocks -cache_size=250000 -threads=4`
using DEBUG_LEVEL=0 and simultaneous before & after runs.
Before ops/sec, avg over 100 runs: 121924
After ops/sec, avg over 100 runs: 125385 (+2.8%)

### Collision probability
I have built a tool, ./cache_bench -stress_cache_key to broadly simulate host-wide cache activity
over many months, by making some pessimistic simplifying assumptions:
* Every generated file has a cache entry for every byte offset in the file (contiguous range of cache keys)
* All of every file is cached for its entire lifetime

We use a simple table with skewed address assignment and replacement on address collision
to simulate files coming & going, with quite a variance (super-Poisson) in ages. Some output
with `./cache_bench -stress_cache_key -sck_keep_bits=40`:

```
Total cache or DBs size: 32TiB  Writing 925.926 MiB/s or 76.2939TiB/day
Multiply by 9.22337e+18 to correct for simulation losses (but still assume whole file cached)
```

These come from default settings of 2.5M files per day of 32 MB each, and
`-sck_keep_bits=40` means that to represent a single file, we are only keeping 40 bits of
the 128-bit cache key.  With file size of 2\*\*25 contiguous keys (pessimistic), our simulation
is about 2\*\*(128-40-25) or about 9 billion billion times more prone to collision than reality.

More default assumptions, relatively pessimistic:
* 100 DBs in same process (doesn't matter much)
* Re-open DB in same process (new session ID related to old session ID) on average
every 100 files generated
* Restart process (all new session IDs unrelated to old) 24 times per day

After enough data, we get a result at the end:

```
(keep 40 bits)  17 collisions after 2 x 90 days, est 10.5882 days between (9.76592e+19 corrected)
```

If we believe the (pessimistic) simulation and the mathematical generalization, we would need to run a billion machines all for 97 billion days to expect a cache key collision. To help verify that our generalization ("corrected") is robust, we can make our simulation more precise with `-sck_keep_bits=41` and `42`, which takes more running time to get enough data:

```
(keep 41 bits)  16 collisions after 4 x 90 days, est 22.5 days between (1.03763e+20 corrected)
(keep 42 bits)  19 collisions after 10 x 90 days, est 47.3684 days between (1.09224e+20 corrected)
```

The generalized prediction still holds. With the `-sck_randomize` option, we can see that we are beating "random" cache keys (except offsets still non-randomized) by a modest amount (roughly 20x less collision prone than random), which should make us reasonably comfortable even in "degenerate" cases:

```
197 collisions after 1 x 90 days, est 0.456853 days between (4.21372e+18 corrected)
```

I've run other tests to validate other conditions behave as expected, never behaving "worse than random" unless we start chopping off structured data.

Reviewed By: zhichao-cao

Differential Revision: D33171746

Pulled By: pdillinger

fbshipit-source-id: f16a57e369ed37be5e7e33525ace848d0537c88f
2021-12-16 17:15:13 -08:00
Peter Dillinger
80ac7412b5 Polish/deflake BackupEngineTest.FileCollision (#9257)
Summary:
Use smaller and more predictable behaviors

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9257

Test Plan:
gtest-parallel --repeat=N ./backupable_db_test --gtest_filter=BackupEngineTest.FileCollision

before (N=50) we see inconsistent sets of SST files

    $ find /dev/shm/rocksdb_blah/ | grep -o '/00.*sst' | grep -o '^[^_]*' | sort | uniq -c
     49 /000009
      3 /000010
      1 /000010.sst
     49 /000012
      3 /000013
      1 /000013.sst
     49 /000015
      2 /000016
      1 /000016.sst
     22 /000018
      2 /000019
      1 /000019.sst
     29 /000020
     11 /000021
      2 /000021.sst
     46 /000022
      2 /000022.sst
      4 /000023
      1 /000023.sst
     27 /000025

And after (N=5000) we see

    $ find /dev/shm/rocksdb_blah/ | grep -o '/00.*sst' | grep -o '^[^_]*' | sort | uniq -c
      10000 /000009
      10000 /000012
       5000 /000015

Reviewed By: ajkr

Differential Revision: D32888393

Pulled By: pdillinger

fbshipit-source-id: 5bfd075b3184bb66c5613758a53f431c406e9808
2021-12-08 21:57:46 -08:00
Hui Xiao
cff7819dff Fix BackupEngine's internal callers of GenericRateLimiter::Request() not honoring bytes <= GetSingleBurstBytes() (#9063)
Summary:
**Context:**
Some existing internal calls of `GenericRateLimiter::Request()` in backupable_db.cc and newly added internal calls in https://github.com/facebook/rocksdb/pull/8722/ do not make sure `bytes <= GetSingleBurstBytes()` as required by rate_limiter https://github.com/facebook/rocksdb/blob/master/include/rocksdb/rate_limiter.h#L47.

**Impacts of this bug include:**
(1) In debug build, when `GenericRateLimiter::Request()` requests bytes greater than `GenericRateLimiter:: kMinRefillBytesPerPeriod = 100` byte, process will crash due to assertion failure. See https://github.com/facebook/rocksdb/pull/9063#discussion_r737034133 and for possible scenario
(2) In production build, although there will not be the above crash due to disabled assertion, the bug can lead to a request of small bytes being blocked for a long time by a request of same priority with insanely large bytes from a different thread. See updated https://github.com/facebook/rocksdb/wiki/Rate-Limiter ("Notice that although....the maximum bytes that can be granted in a single request have to be bounded...") for more info.

There is an on-going effort to move rate-limiting to file wrapper level so rate limiting in `BackupEngine` and this PR might be made obsolete in the future.

**Summary:**
- Implemented loop-calling `GenericRateLimiter::Request()` with `bytes <= GetSingleBurstBytes()` as a static private helper function `BackupEngineImpl::LoopRateLimitRequestHelper`
   -- Considering make this a util function in `RateLimiter` later or do something with `RateLimiter::RequestToken()`
- Replaced buggy internal callers with this helper function wherever requested byte is not pre-limited by `GetSingleBurstBytes()`
- Removed the minimum refill bytes per period enforced by `GenericRateLimiter` since it is useless and prevents testing `GenericRateLimiter` for extreme case with small refill bytes per period.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/9063

Test Plan:
- Added a new test that failed the assertion before this change and now passes
  - It exposed bugs in [the write during creation in `CopyOrCreateFile()`](df7cc66e17/utilities/backupable/backupable_db.cc (L2034-L2043)), [the read of table properties in `GetFileDbIdentities()`](df7cc66e17/utilities/backupable/backupable_db.cc (L2372-L2378)), [some read of metadata in `BackupMeta::LoadFromFile()`](df7cc66e17/utilities/backupable/backupable_db.cc (L2726))
- Passing Existing tests

Reviewed By: ajkr

Differential Revision: D31824535

Pulled By: hx235

fbshipit-source-id: d2b3dea7a64e2a4b1e6a59fca322f0800a4fcbcc
2021-11-16 09:52:16 -08:00
Jay Zhuang
29102641dd Skip directory fsync for filesystem btrfs (#8903)
Summary:
Directory fsync might be expensive on btrfs and it may not be needed.
Here are 4 directory fsync cases:
1. creating a new file: dir-fsync is not needed on btrfs, as long as the
   new file itself is synced.
2. renaming a file: dir-fsync is not needed if the renamed file is
   synced. So an API `FsyncAfterFileRename(filename, ...)` is provided
   to sync the file on btrfs. By default, it just calls dir-fsync.
3. deleting files: dir-fsync is forced by set
   `IOOptions.force_dir_fsync = true`
4. renaming multiple files (like backup and checkpoint): dir-fsync is
   forced, the same as above.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8903

Test Plan: run tests on btrfs and non btrfs

Reviewed By: ajkr

Differential Revision: D30885059

Pulled By: jay-zhuang

fbshipit-source-id: dd2730b31580b0bcaedffc318a762d7dbf25de4a
2021-11-03 12:21:27 -07:00
Peter Dillinger
3ffb3baa0b Add (Live)FileStorageInfo API (#8968)
Summary:
New classes FileStorageInfo and LiveFileStorageInfo and
'experimental' function DB::GetLiveFilesStorageInfo, which is intended
to largely replace several fragmented DB functions needed to create
checkpoints and backups.

This function is now used to create checkpoints and backups, because
it fixes many (probably not all) of the prior complexities of checkpoint
not having atomic access to DB metadata. This also ensures strong
functional test coverage of the new API. Specifically, much of the old
CheckpointImpl::CreateCustomCheckpoint has been migrated to and
updated in DBImpl::GetLiveFilesStorageInfo, with the former now
calling the latter.

Also, the class FileStorageInfo in metadata.h compatibly replaces
BackupFileInfo and serves as a new base class for SstFileMetaData.
Some old fields of SstFileMetaData are still provided (for now) but
deprecated.

Although FileStorageInfo::directory is accurate when using db_paths
and/or cf_paths, these have never been supported by Checkpoint
nor BackupEngine and still are not. This change does now detect
these cases and return NotSupported when appropriate. (More work
needed for support.)

Somehow this change broke ProgressCallbackDuringBackup, but
the progress_callback logic was dubious to begin with because it
would call the callback based on copy buffer size, not size actually
copied. Logic and test updated to track size actually copied
per-thread.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8968

Test Plan:
tests updated.
DB::GetLiveFilesStorageInfo mostly tested by use in CheckpointImpl.
DBTest.SnapshotFiles updated to also test GetLiveFilesStorageInfo,
including reading the data after DB close.
Added CheckpointTest.CheckpointWithDbPath (NotSupported).

Reviewed By: siying

Differential Revision: D31242045

Pulled By: pdillinger

fbshipit-source-id: b183d1ce9799e220daaefd6b3b5365d98de676c0
2021-10-16 10:04:32 -07:00
Peter Dillinger
5268cdc997 Finish BackupEngine migration to IOStatus (#8940)
Summary:
Updates a few remaining functions that should have been updated
from Status -> IOStatus, and adds to HISTORY for the overall change
including https://github.com/facebook/rocksdb/issues/8820.

This change is for inclusion in version 6.25.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8940

Test Plan: CI

Reviewed By: zhichao-cao

Differential Revision: D31085029

Pulled By: pdillinger

fbshipit-source-id: 91557c6a39ef1d90357d4f4dcd79af0645d87c7b
2021-09-21 11:13:17 -07:00
Zhichao Cao
82e7631de6 Replace Status with IOStatus in the backupable_db (#8820)
Summary:
In order to populate the IOStatus up to the higher level, replace some of the Status to IOStatus.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8820

Test Plan: make check

Reviewed By: pdillinger

Differential Revision: D30967215

Pulled By: zhichao-cao

fbshipit-source-id: ccf9d5cfbd9d3de047c464aaa85f9fa43b474903
2021-09-15 15:09:48 -07:00
hx235
45175ca2e1 Charge read to rate limiter in BackupEngine (#8722)
Summary:
Context:
While all the non-trivial write operations in BackupEngine go through the RateLimiter, reads currently do not. In general, this is not a huge issue because (especially since some I/O efficiency fixes) reads in BackupEngine are mostly limited by corresponding writes, for both backup and restore. But in principle we should charge the RateLimiter for reads as well.
- Charged read operations in `BackupEngineImpl::CopyOrCreateFile`, `BackupEngineImpl::ReadFileAndComputeChecksum`, `BackupEngineImpl::BackupMeta::LoadFromFile` and `BackupEngineImpl::GetFileDbIdentities`

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8722

Test Plan:
- Passed existing tests
- Passed added unit tests

Reviewed By: pdillinger

Differential Revision: D30610464

Pulled By: hx235

fbshipit-source-id: 9b08c9387159a5385c8d390d6666377a0d0117e5
2021-09-08 16:24:40 -07:00
Andrew Kryczka
dd092c2d11 prevent stranded LATEST_BACKUP in BackupEngineTest.NoDeleteWithReadOnly (#8887)
Summary:
A "LATEST_BACKUP" file was left in the backup directory by
"BackupEngineTest.NoDeleteWithReadOnly" test, affecting future test
runs. In particular, it caused "BackupEngineTest.IOStats" to fail since
it relies on backup directory containing only data written by its
`BackupEngine`.

The fix is to promote "LATEST_BACKUP" to an explicitly managed file so
it is deleted in `BackupEngineTest` constructor if it exists.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8887

Test Plan:
below command used to fail. Now it passes:

```
$ TEST_TMPDIR=/dev/shm ./backupable_db_test --gtest_filter='BackupEngineTest.NoDeleteWithReadOnly:BackupEngineTest.IOStats'
```

Reviewed By: pdillinger

Differential Revision: D30812336

Pulled By: ajkr

fbshipit-source-id: 32dfbe1368ebdab872e610764bfea5daf9a2af09
2021-09-08 13:39:01 -07:00
Andrew Kryczka
9308ff366c Bytes read/written stats for CreateNewBackup*() (#8819)
Summary:
Gets `Statistics` from the options associated with the `DB` undergoing backup, and populates new ticker stats with the thread-local `IOContext` read/write counters for the threads doing backup work.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8819

Reviewed By: pdillinger

Differential Revision: D30779238

Pulled By: ajkr

fbshipit-source-id: 75ccafc355f90906df5cf80367f7245b985772d8
2021-09-07 18:25:16 -07:00
Peter Dillinger
0ef88538c6 Improve support for using regexes (#8740)
Summary:
* Consolidate use of std::regex for testing to testharness.cc, to
minimize Facebook linters constantly flagging uses in non-production
code.
* Improve syntax and error messages for asserting some string matches a
regex in tests.
* Add a public Regex wrapper class to encapsulate existing usage in
ObjectRegistry.
* Remove unnecessary include <regex>
* Put warnings that use of Regex in production code could cause bad
performance or stack overflow.

Intended follow-up work:
* Replace std::regex with another underlying implementation like RE2
* Improve ObjectRegistry interface in terms of possibly confusing literal
string matching vs. regex and in terms of reporting invalid regex.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8740

Test Plan:
tests updated, basic unit test for public Regex, and some manual
testing of temporary changes to see example error messages:

utilities/backupable/backupable_db_test.cc:917: Failure
000010_1162373755_138626.blob (child.name)
does not match regex
[0-9]+_[0-9]+_[0-9]+[.]blobHAHAHA (pattern)

db/db_basic_test.cc:74: Failure
R3SHSBA8C4U0CIMV2ZB0 (sid3)
does not match regex [0-9A-Z]{20}HAHAHA

Reviewed By: mrambacher

Differential Revision: D30706246

Pulled By: pdillinger

fbshipit-source-id: ba845e8f563ccad39bdb58f44f04e9da8f78c3fd
2021-09-07 13:05:23 -07:00
Peter Dillinger
32752551b9 Fix a buffer size race condition in BackupEngine (#8732)
Summary:
If RateLimiter burst bytes changes during concurrent Restore
operations

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8732

Test Plan: updated unit test fails with TSAN before change, passes after

Reviewed By: ajkr

Differential Revision: D30683879

Pulled By: pdillinger

fbshipit-source-id: d0ddb3587ade91ee2a4d926b475acf7781b03086
2021-09-01 14:28:58 -07:00
Peter Dillinger
a7fd1d0881 Make backup restore atomic, with sync option (#8568)
Summary:
Guarantees that if a restore is interrupted, DB::Open will fail. This works by
restoring CURRENT first to CURRENT.tmp then as a final step renaming to CURRENT.

Also makes restore respect BackupEngineOptions::sync (default true). When set,
the restore is guaranteed persisted by the time it returns OK. Also makes the above
atomicity guarantee work in case the interruption is power loss or OS crash (not just
process interruption or crash).

Fixes https://github.com/facebook/rocksdb/issues/8500

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8568

Test Plan:
added to backup mini-stress unit test. Passes with
gtest_repeat=100 (whereas fails 7 times without the CURRENT.tmp)

Reviewed By: akankshamahajan15

Differential Revision: D29812605

Pulled By: pdillinger

fbshipit-source-id: 24e9a993b305b1835ca95558fa7a7152e54cda8e
2021-08-06 09:50:21 -07:00
Andrew Kryczka
ed8eb436db Move slow valgrind tests behind -DROCKSDB_FULL_VALGRIND_RUN (#8475)
Summary:
Various tests had disabled valgrind due to it slowing down and timing
out (as is the case right now) the CI runs. Where a test was disabled with no comment,
I assumed slowness was the cause. For these tests that were slow under
valgrind, as well as the ones identified in https://github.com/facebook/rocksdb/issues/8352, this PR moves them
behind the compiler flag `-DROCKSDB_FULL_VALGRIND_RUN`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8475

Test Plan: running `make full_valgrind_test`, `make valgrind_test`, `make check`; will verify they appear working correctly

Reviewed By: jay-zhuang

Differential Revision: D29504843

Pulled By: ajkr

fbshipit-source-id: 2aac90749cfbd30d5ce11cb29a07a1b9314eeea7
2021-07-07 11:14:05 -07:00
Peter Dillinger
c26b75baa5 Deprecate obsolete "backupable db" from public APIs (#8274)
Summary:
An early design of BackupEngine used stackable DB, so I guess a
DB had to opt-in to being backupable. Unfortunately the naming of that
obsolete design still infects our public API and implementation.

This change fixes the public API, with a deprecated
backward-compatibility header. `BackupableDBOptions` is renamed to
`BackupEngineOptions` (copy-replace in the public header) and
backup_engine.h replaces backupable_db.h (present for backward
compatibility). The only other change in backupable_db.h ->
backup_engine.h is cleaning up headers.

Later changes will fix the internal implementation.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8274

Test Plan:
The internal implementation of BackupEngine uses the name
BackupEngineOptions, while the unit tests use the old name
BackupableDBOptions. This gives me confidence that both still work.

Reviewed By: mrambacher

Differential Revision: D28259471

Pulled By: pdillinger

fbshipit-source-id: a25dbe327b9772143488e7bb0ec7139ee42d0613
2021-05-07 13:53:15 -07:00
Yanqin Jin
a376c22066 Handle rename() failure in non-local FS (#8192)
Summary:
In a distributed environment, a file `rename()` operation can succeed on server (remote)
side, but the client can somehow return non-ok status to RocksDB. Possible reasons include
network partition, connection issue, etc. This happens in `rocksdb::SetCurrentFile()`, which
can be called in `LogAndApply() -> ProcessManifestWrites()` if RocksDB tries to switch to a
new MANIFEST. We currently always delete the new MANIFEST if an error occurs.

This is problematic in distributed world. If the server-side successfully updates the CURRENT
file via renaming, then a subsequent `DB::Open()` will try to look for the new MANIFEST and fail.

As a fix, we can track the execution result of IO operations on the new MANIFEST.
- If IO operations on the new MANIFEST fail, then we know the CURRENT must point to the original
  MANIFEST. Therefore, it is safe to remove the new MANIFEST.
- If IO operations on the new MANIFEST all succeed, but somehow we end up in the clean up
  code block, then we do not know whether CURRENT points to the new or old MANIFEST. (For local
  POSIX-compliant FS, it should still point to old MANIFEST, but it does not matter if we keep the
  new MANIFEST.) Therefore, we keep the new MANIFEST.
    - Any future `LogAndApply()` will switch to a new MANIFEST and update CURRENT.
    - If process reopens the db immediately after the failure, then the CURRENT file can point
      to either the new MANIFEST or the old one, both of which exist. Therefore, recovery can
      succeed and ignore the other.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8192

Test Plan: make check

Reviewed By: zhichao-cao

Differential Revision: D27804648

Pulled By: riversand963

fbshipit-source-id: 9c16f2a5ce41bc6aadf085e48449b19ede8423e4
2021-04-19 18:11:13 -07:00
Akanksha Mahajan
c377c2ba15 Fix flaky test BackupableDBTest.FileSizeForIncremental (#8197)
Summary:
Test was flaky because for kUseDbSessionId naming, blob files use
naming scheme kLegacyCrc32cAndFileSize. So expected number of files
because of collision can vary. So disabling blobdb for this test case.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8197

Reviewed By: pdillinger

Differential Revision: D27836997

Pulled By: akankshamahajan15

fbshipit-source-id: 5eb21a5f4acae3d6b730a9e1b207264fbc18cb80
2021-04-18 16:18:35 -07:00
Peter Dillinger
bb75092574 Misc Backup API enhancements (#8170)
Summary:
* CreateNewBackup(WithMetadata) returning the BackupID of new backup
through optional new output param. This is especially useful with the
new mutithreading support, so that you can transactionally determine the
ID of a backup you create.
* GetBackupInfo / GetLatestBackupInfo for individual backups, so that
you don't have to comb through a vector of backups if you don't want to.

Updated HISTORY.md (including re: BlobDB support as new feature)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8170

Test Plan:
Added test logic to existing tests, to minimize increase in
cost of running tests

Reviewed By: zhichao-cao

Differential Revision: D27680410

Pulled By: pdillinger

fbshipit-source-id: 1fc45b73d81aae293ccd4a43d9583d7fd915d3eb
2021-04-12 11:00:47 -07:00
Akanksha Mahajan
d52b520d51 Integrated BlobDB for backup/restore support (#8129)
Summary:
Add support for blob files for backup/restore like table files.
    Since DB session ID is currently not supported for blob files (there is no place to store it in
    the header), so for blob files uses the
    kLegacyCrc32cAndFileSize naming scheme even if
    share_files_with_checksum_naming is set to kUseDbSessionId.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8129

Test Plan: Add new test units

Reviewed By: ltamasi

Differential Revision: D27408510

Pulled By: akankshamahajan15

fbshipit-source-id: b27434d189a639ef3e6ad165c61a143a2daaf06e
2021-04-07 13:38:54 -07:00
Peter Dillinger
a4e82a3cca Fix read-only DB writing to filesystem with write_dbid_to_manifest (#8164)
Summary:
Fixing another crash test failure in the case of
write_dbid_to_manifest=true and reading a backup as read-only DB.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8164

Test Plan:
enhanced unit test for backup as read-only DB, ran
blackbox_crash_test more with elevated backup_one_in

Reviewed By: zhichao-cao

Differential Revision: D27622237

Pulled By: pdillinger

fbshipit-source-id: 680d0f99ddb465a601737f2e3f2c80efd47384fb
2021-04-07 10:26:47 -07:00
Peter Dillinger
35af0433cf Fix crash test with backup as read-only DB (#8161)
Summary:
Forgot to re-test crash test after adding read-only filesystem
enforcement to https://github.com/facebook/rocksdb/issues/8142. The problem is ReadOnlyFileSystem would reject
CreateDirIfMissing whenever DBOptions::create_if_missing=true. The fix
that is better for users is to allow CreateDirIfMissing in
ReadOnlyFileSystem if the directory exists, so that they don't cause a
failure on using create_if_missing with opening backups as read-only
DBs. Added this option test to the unit test (in addition to being in the
crash test).

Also fixed a couple of lints.

And some better messaging from 'make format' so that when you run it
with uncommitted changes, it's clear that it's only checking the
uncommitted changes.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8161

Test Plan: local blackbox_crash_test with amplified backup_one_in

Reviewed By: ajkr

Differential Revision: D27614409

Pulled By: pdillinger

fbshipit-source-id: 63ccb626c7e34c200d61c6bca2a8f60da9015179
2021-04-06 23:31:51 -07:00
Peter Dillinger
879357fdb0 Make backups openable as read-only DBs (#8142)
Summary:
A current limitation of backups is that you don't know the
exact database state of when the backup was taken. With this new
feature, you can at least inspect the backup's DB state without
restoring it by opening it as a read-only DB.

Rather than add something like OpenAsReadOnlyDB to the BackupEngine API,
which would inhibit opening stackable DB implementations read-only
(if/when their APIs support it), we instead provide a DB name and Env
that can be used to open as a read-only DB.

Possible follow-up work:

* Add a version of GetBackupInfo for a single backup.
* Let CreateNewBackup return the BackupID of the newly-created backup.

Implementation details:

Refactored ChrootFileSystem to split off new base class RemapFileSystem,
which allows more general remapping of files. We use this base class to
implement BackupEngineImpl::RemapSharedFileSystem.

To minimize API impact, I decided to just add these fields `name_for_open`
and `env_for_open` to those set by GetBackupInfo when
include_file_details=true. Creating the RemapSharedFileSystem adds a bit
to the memory consumption, perhaps unnecessarily in some cases, but this
has been mitigated by (a) only initialize the RemapSharedFileSystem
lazily when GetBackupInfo with include_file_details=true is called, and
(b) using the existing `shared_ptr<FileInfo>` objects to hold most of the
mapping data.

To enhance API safety, RemapSharedFileSystem is wrapped by new
ReadOnlyFileSystem which rejects any attempts to write. This uncovered a
couple of places in which DB::OpenForReadOnly would write to the
filesystem, so I fixed these. Added a release note because this affects
logging.

Additional minor refactoring in backupable_db.cc to support the new
functionality.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8142

Test Plan:
new test (run with ASAN and UBSAN), added to stress test and
ran it for a while with amplified backup_one_in

Reviewed By: ajkr

Differential Revision: D27535408

Pulled By: pdillinger

fbshipit-source-id: 04666d310aa0261ef6b2385c43ca793ce1dfd148
2021-04-06 14:37:53 -07:00
Peter Dillinger
96205baa63 Likely fix flaky TableFileCorruptedBeforeBackup (#8151)
Summary:
Before corrupting a file in the DB and expecting corruption to
be detected, open DB read-only to ensure file is not made obsolete by
compaction. Also, to avoid obsolete files not yet deleted, only select
live files to corrupt.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8151

Test Plan: watch CI

Reviewed By: akankshamahajan15

Differential Revision: D27568849

Pulled By: pdillinger

fbshipit-source-id: 39a69a2eafde0482b20a197949d24abe21952f27
2021-04-05 11:40:31 -07:00
Peter Dillinger
ec11c23caa Add thread safety to BackupEngine, explain more (#8115)
Summary:
BackupEngine previously had unclear but strict concurrency
requirements that the API user must follow for safe use. Now we make
that clear, by separating operations into "Read," "Append," and "Write"
operations, and specifying which combinations are safe across threads on
the same BackupEngine object (previously none; now all, using a
read-write lock), and which are safe across different BackupEngine
instances open on the same backup_dir.

The changes to backupable_db.h should be backward compatible. It is
mostly about eliminating copies of what should be the same function and
(unsurprisingly) useful documentation comments were often placed on
only one of the two copies. With the re-organization, we are also
grouping different categories of operations. In the future we might add
BackupEngineReadAppendOnly, but that didn't seem necessary.

To mark API Read operations 'const', I had to mark some implementation
functions 'const' and some fields mutable.

Functional changes:
* Added RWMutex locking around public API functions to implement thread
safety on a single object. To avoid future bugs, this is another
internal class layered on top (removing many "override" in
BackupEngineImpl). It would be possible to allow more concurrency
between operations, rather than mutual exclusion, but IMHO not worth the
work.
* Fixed a race between Open() (Initialize()) and CreateNewBackup() for
different objects on the same backup_dir, where Initialize() could
delete the temporary meta file created during CreateNewBackup().
(This was found by the new test.)

Also cleaned up a couple of "status checked" TODOs, and improved a
checksum mismatch error message to include involved files.

Potential follow-up work:
* CreateNewBackup has an API wart because it doesn't tell you the
BackupID it just created, which makes it of limited use in a multithreaded
setting.
* We could also consider a Refresh() function to catch up to
changes made from another BackupEngine object to the same dir.
* Use a lock file to prevent multiple writer BackupEngines, but this
won't work on remote filesystems not supporting lock files.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8115

Test Plan:
new mini-stress test in backup unit tests, run with gcc,
clang, ASC, TSAN, and UBSAN, 100 iterations each.

Reviewed By: ajkr

Differential Revision: D27347589

Pulled By: pdillinger

fbshipit-source-id: 28d82ed2ac672e44085a739ddb19d297dad14b15
2021-03-29 22:41:51 -07:00
Peter Dillinger
3bfd3ed2f3 Begin forward compatibility for new backup meta schema (#8069)
Summary:
This does not add any new public APIs or published
functionality, but adds the ability to read and use (and in tests,
write) backups with a new meta file schema, based on the old schema
but not forward-compatible (before this change). The new schema enables
some capabilities not in the old:

* Explicit versioning, so that users get clean error messages the next
time we want to break forward compatibility.
* Ignoring unrecognized fields (with warning), so that new non-critical
features can be added without breaking forward compatibility.
* Rejecting future "non-ignorable" fields, so that new features critical
to some use-cases could potentially be added outside of linear schema
versions, with broken forward compatibility.
* Fields at the end of the meta file, such as for checksum of the meta
file's contents (up to that point)
* New optional 'size' field for each file, which is checked when present
* Optionally omitting 'crc32' field, so that we aren't required to have
a crc32c checksum for files to take a backup. (E.g. to support backup
via hard links and to better support file custom checksums.)

Because we do not have a JSON parser and to share code, the new schema
is simply derived from the old schema.

BackupEngine code is updated to allow missing checksums in some places,
and to make that easier, `has_checksum` and `verify_checksum_after_work`
are eliminated. Empty `checksum_hex` indicates checksum is unknown. I'm
not too afraid of regressing on data integrity, because
(a) we have pretty good test coverage of corruption detection in backups, and
(b) we are increasingly relying on the DB itself for data integrity rather than
it being an exclusive feature of backups.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8069

Test Plan:
new unit tests, added to crash test (some local run with
boosted backup probability)

Reviewed By: ajkr

Differential Revision: D27139824

Pulled By: pdillinger

fbshipit-source-id: 9e0e4decfb42bb84783d64d2d246456d97e8e8c5
2021-03-19 20:15:40 -07:00
Yanqin Jin
7ee41a5d25 Fix a test failure when built with ASSERT_STATUS_CHECKED=1 (#8075)
Summary:
As title.
Test plan
ASSERT_STATUS_CHECKED=1 make -j20 backupable_db_test error_handler_fs_test
./backupable_db_test
./error_handler_fs_test

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8075

Reviewed By: zhichao-cao

Differential Revision: D27173832

Pulled By: riversand963

fbshipit-source-id: 37dac50f7c89127804ff2572abddd4174642de30
2021-03-18 21:52:48 -07:00
Peter Dillinger
589ea6bec2 Add BackupEngine API for backup file details (#8042)
Summary:
This API can be used for things like determining how much space
can be freed up by deleting a particular backup, etc.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8042

Test Plan:
validation of the API added to many existing backup unit
tests

Reviewed By: mrambacher

Differential Revision: D26936577

Pulled By: pdillinger

fbshipit-source-id: f0bbd90f0917b9781a6837652fb4616d9247816a
2021-03-12 11:03:54 -08:00
Peter Dillinger
4b18c46d10 Refactor: add LineFileReader and Status::MustCheck (#8026)
Summary:
Removed confusing, awkward, and undocumented internal API
ReadOneLine and replaced with very simple LineFileReader.

In refactoring backupable_db.cc, this has the side benefit of
removing the arbitrary cap on the size of backup metadata files.

Also added Status::MustCheck to make it easy to mark a Status as
"must check." Using this, I can ensure that after
LineFileReader::ReadLine returns false the caller checks GetStatus().

Also removed some excessive conditional compilation in status.h

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8026

Test Plan: added unit test, and running tests with ASSERT_STATUS_CHECKED

Reviewed By: mrambacher

Differential Revision: D26831687

Pulled By: pdillinger

fbshipit-source-id: ef749c265a7a26bb13cd44f6f0f97db2955f6f0f
2021-03-09 20:12:38 -08:00
Peter Dillinger
847ca9f964 Make default share_files_with_checksum=true (#8020)
Summary:
New comment for share_files_with_checksum:
// Only used if share_table_files is set to true. Setting to false is
// DEPRECATED and potentially dangerous because in that case BackupEngine
// can lose data if backing up databases with distinct or divergent
// history, for example if restoring from a backup other than the latest,
// writing to the DB, and creating another backup. Setting to true (default)
// prevents these issues by ensuring that different table files (SSTs) with
// the same number are treated as distinct. See
// share_files_with_checksum_naming and ShareFilesNaming.

I have also removed interim option kFlagMatchInterimNaming, which is no
longer needed and was never needed for correct+compatible operation
(just performance).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8020

Test Plan:
tests updated. Backward+forward compatibility verified with
SHORT_TEST=1 check_format_compatible.sh. ldb uses default backup
options, and I manually verified shared_checksum in
/tmp/rocksdb_format_compatible_peterd/bak/current/ after run.

Reviewed By: ajkr

Differential Revision: D26786331

Pulled By: pdillinger

fbshipit-source-id: 36f968dfef1f5cacbd65154abe1d846151a55130
2021-03-09 16:27:13 -08:00
Akanksha Mahajan
f19612970d Support retrieving checksums for blob files from the MANIFEST when checkpointing (#8003)
Summary:
The checkpointing logic supports passing file level checksums
to the copy_file_cb callback function which is used by the backup code
for detecting corruption during file copies.
However, this is currently implemented only for table files.

This PR extends the checksum retrieval to blob files as well.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8003

Test Plan: Add new test units

Reviewed By: ltamasi

Differential Revision: D26680701

Pulled By: akankshamahajan15

fbshipit-source-id: 1bd1e2464df6e9aa31091d35b8c72786d94cd1c5
2021-03-01 20:07:07 -08:00
mrambacher
4a09d632c4 Remove Legacy and Custom FileWrapper classes from header files (#7851)
Summary:
Removed the uses of the Legacy FileWrapper classes from the source code.  The wrappers were creating an additional layer of indirection/wrapping, as the Env already has a FileSystem.

Moved the Custom FileWrapper classes into the CustomEnv, as these classes are really for the private use the the CustomEnv class.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7851

Reviewed By: anand1976

Differential Revision: D26114816

Pulled By: mrambacher

fbshipit-source-id: db32840e58d969d3a0fa6c25aaf13d6dcdc74150
2021-01-28 22:10:32 -08:00
Adam Retter
4926b33742 Improvements to Env::GetChildren (#7819)
Summary:
The main improvement here is to not include `.` or `..` in the results of `Env::GetChildren`. The occurrence of `.` or `..`; it is non-portable, dependent on the Operating System and the File System. See: https://www.gnu.org/software/libc/manual/html_node/Reading_002fClosing-Directory.html

There were lots of duplicate checks spread through the RocksDB codebase previously to skip `.` and `..`. This new removes the need for those at the source.

Also some minor fixes to `Env::GetChildren`:
* Improve error handling in POSIX implementation
* Remove unnecessary array allocation on Windows
* Fix struct name for Windows Non-UTF-8 API

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7819

Reviewed By: ajkr

Differential Revision: D25837394

Pulled By: jay-zhuang

fbshipit-source-id: 1e137e7218d38b450af9c083f73d5357abcbba2e
2021-01-09 09:44:34 -08:00
mrambacher
cc2a180d00 Add more tests to the ASC pass list (#7834)
Summary:
Fixed the following  to now pass ASC checks:
* `ttl_test`
* `blob_db_test`
* `backupable_db_test`,
* `delete_scheduler_test`

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7834

Reviewed By: jay-zhuang

Differential Revision: D25795398

Pulled By: ajkr

fbshipit-source-id: a10037817deda4fc7cbb353a2e00b62ed89b6476
2021-01-07 15:22:53 -08:00
cheng-chang
bdb7e544bd Skip WALs according to MinLogNumberToKeep when creating checkpoint (#7789)
Summary:
In a stress test failure, we observe that a WAL is skipped when creating checkpoint, although its log number >= MinLogNumberToKeep(). This might happen in the following case:

1. when creating the checkpoint, there are 2 column families: CF0 and CF1, and there are 2 WALs: 1, 2;
2. CF0's log number is 1, CF0's active memtable is empty, CF1's log number is 2, CF1's active memtable is not empty, WAL 2 is not empty, the sequence number points to WAL 2;
2. the checkpoint process flushes CF0, since CF0' active memtable is empty, there is no need to SwitchMemtable, thus no new WAL will be created, so CF0's log number is now 2, concurrently, some data is written to CF0 and WAL 2;
3. the checkpoint process flushes CF1, WAL 3 is created and CF1's log number is now 3, CF0's log number is still 2 because CF0 is not empty and WAL 2 contains its unflushed data concurrently written in step 2;
4.  the checkpoint process determines that WAL 1 and 2 are no longer needed according to [live_wal_files[i]->StartSequence() >= *sequence_number](https://github.com/facebook/rocksdb/blob/master/utilities/checkpoint/checkpoint_impl.cc#L388), so it skips linking them to the checkpoint directory;
5. but according to `MinLogNumberToKeep()`, WAL 2 still needs to be kept because CF0's log number is 2.

If the checkpoint is reopened in read-only mode, and only read from the snapshot with the initial sequence number, then there will be no data loss or data inconsistency.

But if the checkpoint is reopened and read from the most recent sequence number, suppose in step 3, there are also data concurrently written to CF1 and WAL 3, then the most recent sequence number refers to the latest entry in WAL 3, so the data written in step 2 should also be visible, but since WAL 2 is discarded, those data are lost.

When tracking WAL in MANIFEST is enabled, when reopening the checkpoint, since WAL 2 is still tracked in MANIFEST as alive, but it's missing from the checkpoint directory, a corruption will be reported.

This PR makes the checkpoint process to only skip a WAL if its log number < `MinLogNumberToKeep`.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7789

Test Plan: watch existing tests to pass.

Reviewed By: ajkr

Differential Revision: D25662346

Pulled By: cheng-chang

fbshipit-source-id: 136471095baa01886cf44809455cf855f24857a0
2020-12-23 11:33:26 -08:00
Akanksha Mahajan
20c7d7c58a Handling misuse of snprintf return value (#7686)
Summary:
Handle misuse of snprintf return value to avoid Out of bound
read/write.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7686

Test Plan: make check -j64

Reviewed By: riversand963

Differential Revision: D25030831

Pulled By: akankshamahajan15

fbshipit-source-id: 1a1d181c067c78b94d720323ae00b79566b57cfa
2020-12-07 13:43:55 -08:00
Cheng Chang
5e794b0841 Fix a recovery corner case (#7621)
Summary:
Consider the following sequence of events:

1. Db flushed an SST with file number N, appended to MANIFEST, and tried to sync the MANIFEST.
2. Syncing MANIFEST failed and db crashed.
3. Db tried to recover with this MANIFEST. In the meantime, no entry about the newly-flushed SST was found in the MANIFEST. Therefore, RocksDB replayed WAL and tried to flush to an SST file reusing the same file number N. This failed because file system does not support overwrite. Then Db deleted this file.
4. Db crashed again.
5. Db tried to recover. When db read the MANIFEST, there was an entry referencing N.sst. This could happen probably because the append in step 1 finally reached the MANIFEST and became visible. Since N.sst had been deleted in step 3, recovery failed.

It is possible that N.sst created in step 1 is valid. Although step 3 would still fail since the MANIFEST was not synced properly in step 1 and 2, deleting N.sst would make it impossible for the db to recover even if the remaining part of MANIFEST was appended and visible after step 5.

After this PR, in step 3, immediately after recovering from MANIFEST, a new MANIFEST is created, then we find that N.sst is not referenced in the MANIFEST, so we delete it, and we'll not reuse N as file number. Then in step 5, since the new MANIFEST does not contain N.sst, the recovery failure situation in step 5 won't happen.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7621

Test Plan:
1. some tests are updated, because these tests assume that new MANIFEST is created after WAL recovery.
2. a new unit test is added in db_basic_test to simulate step 3.

Reviewed By: riversand963

Differential Revision: D24668144

Pulled By: cheng-chang

fbshipit-source-id: 90d7487fbad2bc3714f5ede46ea949895b15ae3b
2020-11-07 22:23:27 -08:00
Zhichao Cao
d8ec0a760a Make FileType Public and Replace kLogFile with kWalFile (#7580)
Summary:
As suggested by pdillinger ,The name of kLogFile is misleading, in some tests, kLogFile is defined as info log. Replace it with kWalFile and move it to public, which will be used in https://github.com/facebook/rocksdb/issues/7523

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7580

Test Plan: make check

Reviewed By: riversand963

Differential Revision: D24485420

Pulled By: zhichao-cao

fbshipit-source-id: 955e3dacc1021bb590fde93b0a568ffe9ad80799
2020-10-22 17:06:20 -07:00
Jay Zhuang
e127fe18c3 Fix TSAN failure for backupable_db_test (#7478)
Summary:
It's a transient failure, but can be reproduce with running the test 100
times:
https://app.circleci.com/pipelines/github/facebook/rocksdb/3760/workflows/de909685-f22b-45ba-a8f3-6ebb78a54e96/jobs/37039

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7478

Test Plan: re-run the test 100 times

Reviewed By: ajkr

Differential Revision: D24035758

Pulled By: jay-zhuang

fbshipit-source-id: 6b31983d5c3f7faa8d5481306098513485d0d69d
2020-09-30 17:22:56 -07:00
Peter Dillinger
9d8eb77c4d Less I/O for incremental backups, slightly better corruption detection (#7413)
Summary:
Two relatively simple functional changes to incremental backup
behavior, integrated with a minor refactoring to reduce code redundancy and
improve error/log message. There are nuances to the impact of these changes,
but I believe they are fundamentally good and generally safe. Those functional
changes:

* Incremental backups no longer read DB table files that are already saved to a
shared part of the backup directory, unless `share_files_with_checksum` is used
with `kLegacyCrc32cAndFileSize` naming (discouraged) where crc32c full file
checksums are needed to determine file naming.
  * Justification: incremental backups should not need to read the whole DB,
especially without rate limiting. (Although other BackupEngine reads are not
rate limited either, other non-trivial reads are generally limited by a
corresponding write, as in copying files.) Also, the fact that this is not
already fixed was arguably a bug/oversight in the implementation of https://github.com/facebook/rocksdb/issues/7110.

* When considering whether a table file is already backed up in a shared part
of backup directory, BackupEngine would already query the sizes of source (DB)
and pre-existing destination (backup) files. BackupEngine now uses these file
sizes to detect corruption, as at least one of (a) old backup, (b) backup in
progress, or (c) current DB is corrupt if there's a size mismatch.
  * Justification: a random related fix that also helps to cover a small hole
in corruption checking uncovered by the other functional change:
  * For `share_table_files` without "checksum" (not recommended), the other
change regresses in detecting fundamentally unsafe use of this option
combination: when you might generate different versions of same SST file
number. As demonstrated by `BackupableDBTest.FailOverwritingBackups,` this
regression is greatly mitigated by the new file size checking. Nevertheless,
almost no reason to use `share_files_with_checksum=false` should remain, and
comments are updated appropriately.

Also, this change renames internal function `CalculateChecksum` to
`ReadFileAndComputeChecksum` to make the performance impact of this function
clear in code reviews.

It is not clear what 'same_path' is for in backupable_db.cc, and I suspect it
cannot be true for a DB with unique file names (like DBImpl). Nevertheless,
I've tried to keep its functionality intact when `true` to minimize risk for
now, despite having no unit tests for which it is true.

Select impact details (much more in unit tests): For
`share_files_with_checksum`, I am confident there is no regression (vs.
pre-6.12) in detecting DB or backup corruption at backup creation time, mostly
because the old design did not leverage this extra checksum computation for
detecting inconsistencies at backup creation time. (With computed checksums in
names, a recently corrupted file just looked like a different file vs. what was
already backed up.)

Even in the hypothetical case of DB session id collision (~100 bits entropy
collision), file size in name and/or our file size check add an extra layer of
protection against false success in creating an accurate new backup. (Unit test
included.)

`DB::VerifyChecksum` and `BackupEngine::VerifyBackup` with checksum checking
are still able to catch corruptions that `CreateNewBackup` does not. Note that
when custom file checksum support is added to BackupEngine, that will
essentially give the same power as `DB::VerifyChecksum` into `CreateNewBackup`.
We could add options for `CreateNewBackup` to cover some of what would be
caught by `VerifyBackup` with checksum checking.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7413

Test Plan:
Two new unit tests included, both of which fail without these
changes. Although we don't test the I/O improvement directly, we test it
indirectly in DB corruption detection power that was inadvertently unlocked
with new backup file naming PLUS computing current content checksums (now
removed). (I don't think that case of DB corruption detection justifies reading
the whole DB on incremental backup.)

Reviewed By: zhichao-cao

Differential Revision: D23818480

Pulled By: pdillinger

fbshipit-source-id: 148aff16f001af5b9fd4b22f155311c2461f1bac
2020-09-21 16:19:24 -07:00
Peter Dillinger
b475a83f9d Postponing custom checksum support in BackupEngine (#7411)
Summary:
This change reverts BackupEngine to 6.12 state to accommodate a
higher-priority fix that does not easily merge with this custom checksum
support. We intend to reinstate this support soon, by merging a revert
of this change.

For backupable_db_test, I've removed the tests depending on this
feature.

I've also removed relevant HISTORY.md entry.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7411

Test Plan: unit tests

Reviewed By: ajkr

Differential Revision: D23793835

Pulled By: pdillinger

fbshipit-source-id: 7e861436539584799b13d1a8ae559b81b6d08052
2020-09-18 15:27:03 -07:00
Peter Dillinger
93719fc953 Restore file size in backup table file names (and other cleanup) (#7400)
Summary:
Prior to 6.12, backup files using share_files_with_checksum had
the file size encoded in the file name, after the last '\_' and before
the last '.'. We considered this an implementation detail subject to
change, and indeed removed this information from the file name (with an
option to use old behavior) because it was considered
ineffective/inefficient for file name uniqueness. However, some
downstream RocksDB users were relying on this information since the file
size is not explicitly in the backup manifest file.

This primary purpose of this change is "retrofitting" the 6.12 release
(not yet a public release) to simultaneously support the benefits of the
new naming scheme (I/O performance and data correctness at scale) and
preserve the file size information, both as default behaviors. With this
change, we are essentially making the file size information encoded in
the file name an official, though obscure, extension of the backup meta
file format.

We preserve an option (kLegacyCrc32cAndFileSize) to use the original
"legacy" naming scheme, with its caveats, and make it easy to omit the
file size information (no kFlagIncludeFileSize), for more compact file
names. But note that changing the naming scheme used on an existing db
and backup directory can lead to transient space amplification, as some
files will be stored under two names in the shared_checksum directory.
Because some backups were saved using the original 6.12 naming scheme,
we offer two ways of dealing with those files: SST files generated by
older 6.12 versions can either use the default naming scheme in effect
when the SST files were generated (kFlagMatchInterimNaming, default, no
transient space amplification) or can use a new naming scheme (no
kFlagMatchInterimNaming, potential space amplification because some
already stored files getting a new name).

We don't have a natural way to detect which files were generated by
previous 6.12 versions, but this change hacks one in by changing DB
session ids to now use a more concise encoding, reducing file name
length, saving ~dozen bytes from SST files, and making them visually
distinct from DB ids so that they are less likely to be mixed up.

Two final auxiliary notes:
Recognizing that the backup file names have become a de facto part of
the backup meta schema, this change makes them easier to parse and
extend by putting a distinct marker, 's', before DB session ids embedded
in the name. When we extend this to allow custom checksums in the name,
they can get their own marker to ensure safe parsing. For backward
compatibility, file size does not get a marker but is assumed for
`_[0-9]+[.]`

Another change from initial 6.12 default behavior is never including
file custom checksum in the file name. Looking ahead to 6.13, we do not
want the default behavior to cause backup space amplification for
someone turning on file custom checksum checking in BackupEngine; we
want that to be an easy decision. When implemented, including file
custom checksums in backup file names will be a non-default option.

Actual file name patterns and priorities, as regexes:

    kLegacyCrc32cAndFileSize OR pre-6.12 SST file ->
      [0-9]+_[0-9]+_[0-9]+[.]sst
    kFlagMatchInterimNaming set (default) AND early 6.12 SST file ->
      [0-9]+_[0-9a-fA-F-]+[.]sst
    kUseDbSessionId AND NOT kFlagIncludeFileSize ->
      [0-9]+_s[0-9A-Z]{20}[.]sst
    kUseDbSessionId AND kFlagIncludeFileSize (default) ->
      [0-9]+_s[0-9A-Z]{20}_[0-9]+[.]sst

We might add opt-in options for more '\_' separated data in the name,
but embedded file size, if present, will always be after last '\_' and
before '.sst'.

This change was originally applied to version 6.12. (See https://github.com/facebook/rocksdb/issues/7390)

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7400

Test Plan:
unit tests included. Sync point callbacks are used to mimic
previous version SST files.

Reviewed By: ajkr

Differential Revision: D23759587

Pulled By: pdillinger

fbshipit-source-id: f62d8af4e0978de0a34f26288cfbe66049b70025
2020-09-17 10:24:22 -07:00
Peter Dillinger
4e258d3e63 Fix backup/restore in stress/crash test (#7357)
Summary:
(1) Skip check on specific key if restoring an old backup
(small minority of cases) because it can fail in those cases. (2) Remove
an old assertion about number of column families and number of keys
passed in, which is broken by atomic flush (cf_consistency) test. Like
other code (for better or worse) assume a single key and iterate over
column families. (3) Apply mock_direct_io to NewSequentialFile so that
db_stress backup works on /dev/shm.

Also add more context to output in case of backup/restore db_stress
failure.

Also a minor fix to BackupEngine to report first failure status in
creating new backup, and drop another clue about the potential
source of a "Backup failed" status.

Reverts "Disable backup/restore stress test (https://github.com/facebook/rocksdb/issues/7350)"

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7357

Test Plan:
Using backup_one_in=10000,
"USE_CLANG=1 make crash_test_with_atomic_flush" for 30+ minutes
"USE_CLANG=1 make blackbox_crash_test" for 30+ minutes
And with use_direct_reads with TEST_TMPDIR=/dev/shm/rocksdb

Reviewed By: riversand963

Differential Revision: D23567244

Pulled By: pdillinger

fbshipit-source-id: e77171c2e8394d173917e36898c02dead1c40b77
2020-09-08 10:50:19 -07:00
Peter Dillinger
9aad24da55 Real fix for race in backup custom checksum checking (#7309)
Summary:
This is a "real" fix for the issue worked around in https://github.com/facebook/rocksdb/issues/7294.
To get DB checksum info for live files, we now read the manifest file
that will become part of the checkpoint/backup. This requires a little
extra handling in taking a custom checkpoint, including only reading the
manifest file up to the size prescribed by the checkpoint.

This moves GetFileChecksumsFromManifest from backup code to
file_checksum_helper.{h,cc} and removes apparently unnecessary checking
related to column families.

Updated HISTORY.md and warned potential future users of
DB::GetLiveFilesChecksumInfo()

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7309

Test Plan: updated unit test, before and after

Reviewed By: ajkr

Differential Revision: D23311994

Pulled By: pdillinger

fbshipit-source-id: 741e30a2dc1830e8208f7648fcc8c5f000d4e2d5
2020-08-26 10:39:20 -07:00
Peter Dillinger
a1b5484811 Work around a backup bug with DB custom checksums (#7294)
Summary:
On a read-write DB configured with
DBOptions::file_checksum_gen_factory, BackupEngine::CreateNewBackup can
fail intermittently, with non-OK status. This is due to a race between
GetLiveFiles and GetLiveFilesChecksumInfo in creating backups.

For patching 6.12 release (as this commit is intended for, except this is a
forward-merged version), we can simply treat files for which we falsely failed
to get checksum info as legacy files lacking checksum info.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7294

Test Plan: unit test reproducer included

Reviewed By: ajkr

Differential Revision: D23253489

Pulled By: pdillinger

fbshipit-source-id: 9e4945dad120b776ad3e753be10b962f61f28e14
2020-08-21 08:16:04 -07:00
Peter Dillinger
7d0ecab570 Fix some flaky tests in BackupableDBTest with intentional flushing (#7273)
Summary:
Some tests like BackupableDBTest.FileCollision and
ShareTableFilesWithChecksumsNewNaming are intermittently failing,
probably due to unpredictable flushing with FillDB. This change
should fix the failures seen and help to prevent similar flakiness in
future tests in the file.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7273

Test Plan: make check, and with valgrind

Reviewed By: siying

Differential Revision: D23176947

Pulled By: pdillinger

fbshipit-source-id: 654b73a64db475f2b9b065ed53a889a8b9083c59
2020-08-17 22:07:17 -07:00
Zitan Chen
500eeb6fd3 Re-enable param tests for backup engine (#7260)
Summary:
The param tests did not take any effect previously. This PR re-enables it.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7260

Test Plan: Some manual tests and `./backupable_db_test`.

Reviewed By: siying

Differential Revision: D23140902

Pulled By: pdillinger

fbshipit-source-id: cd62b11b926affed25127d9074fa97a1c7f748c4
2020-08-17 13:59:21 -07:00