BTRFS reorders rename and write operations, so it is possible that a filesystem crash and recovery results in a situation where the file pointed to by CURRENT does not exist. DB::Open currently reports an I/O error in this case. Reporting database corruption is a better hint to the caller, which can attempt to recover the database or erase it and start over.
This issue is not merely theoretical. It was reported as having showed up in the wild at https://github.com/google/leveldb/issues/195 and at https://crbug.com/738961. Also, asides from the BTRFS case described above, incorrect data in CURRENT seems like a possible corruption case that should be handled gracefully.
The Env API changes here can be considered backwards compatible, because an implementation that returns Status::IOError instead of Status::NotFound will still get the same functionality as before.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=161432630
Markdown is more readable in a text editor and when hosted
on GitHub is more readable than HTML.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148830423
Detailed description:
Suppose an input split is generated between two leveldb record blocks and the preceding block ends with null padding.
A reader that previously read at least 1 record within the first block (before encountering the padding) upon trying to read the next record, will successfully and correctly read the next logical record from the subsequent block, but will return a last record offset pointing to the padding in the first block.
When this happened in a [], it resulted in duplicate records being handled at what appeared to be different offsets that were separated by only a few bytes.
This behavior is only observed when at least 1 record was read from the first block before encountering the padding. If the initial offset for a reader was within the padding, the correct record offset would be reported, namely the offset within the second block.
The tests failed to catch this scenario/bug, because each read test only read a single record with an initial offset. This CL adds an explicit test case for this scenario, and modifies the test structure to read all remaining records in the test case after an initial offset is specified. Thus an initial offset that jumps to record #3, with 5 total records in the test file, will result in reading 2 records, and validating the offset of each of them in order to pass successfully.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=115338487
1. Object files, libraries, and compiled executables are put
into subdirectories.
2. The shared library is linked from individual object files.
This provides for greater parallelism on large desktops
while at the same time making for easier builds on small
(i.e. embedded) systems. Fixes issue #279.
3. One program, db_bench, is compiled using the shared library.
4. The source file for "leveldbutil" was renamed from
leveldb_main.cc to leveldbutil.cc. This provides for simpler
makefile rules.
5. Because all targets placed the library (libleveldb.a) at the top
level, the last platform built (desktop/device) always overwrote
any prior artifact.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=113407013
The write operations in the table happens without holding the mutex
lock, but concurrent writes are avoided using "writers_" queue.
The Arena::MemoryUsage could access the blocks when write happens.
So, the memory usage is cached in atomic word and can be loaded
from any thread safely.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=107573379
The approximate RAM usage of the database is calculated from the memory
allocated for write buffers and the block cache. This is to give an
estimate of memory usage to leveldb clients.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=104222307
Prior implementation would always try to reuse the manifest, even if reuse_logs
was false (the default). This was missed because the stock
Env::NewAppendableFile implementation returns false forcing the creation of a
new log.
(Based on a suggestion by cmumford.)
"open" benchmark on my workstation speeds up significantly since we
can now avoid three fdatasync calls and a compaction per open:
Before: ~80000 microseconds
After: ~130 microseconds
Details:
(1) Added Options::reuse_logs (currently defaults to false) to control
new behavior. The intention is to change the default to true after some
baking.
(2) Added Env::NewAppendableFile() whose default implementation returns
a not-supported error.
(3) VersionSet::Recovery attempts to reuse the MANIFEST from which
it is recovering.
(4) DBImpl recovery attempts to reuse the last log file and memtable.
(5) db_test.cc now tests a new configuration that sets reuse_logs to true.
(6) fault_injection_test also tests a reuse_logs==true config.
(7) Added a new recovery_test.
This test is intended to ensure leveldb properly detects and recovers from
faults - specifically unwritten file data lost as a result of a system reset.
Changes are:
* Update version number to 1.18
* Replace the basic fprintf call with a call to fwrite in order to
work around the apparent compiler optimization/rewrite failure that we are
seeing with the new toolchain/iOS SDKs provided with Xcode6 and iOS8.
* Fix ALL the header guards.
* Createed a README.md with the LevelDB project description.
* A new CONTRIBUTING file.
* Don't implicitly convert uint64_t to size_t or int. Either preserve it as
uint64_t, or explicitly cast. This fixes MSVC warnings about possible value
truncation when compiling this code in Chromium.
* Added a DumpFile() library function that encapsulates the guts of the
"leveldbutil dump" command. This will allow clients to dump
data to their log files instead of stdout. It will also allow clients to
supply their own environment.
* leveldb: Remove unused function 'ConsumeChar'.
* leveldbutil: Remove unused member variables from WriteBatchItemPrinter.
* OpenBSD, NetBSD and DragonflyBSD have _LITTLE_ENDIAN, so define
PLATFORM_IS_LITTLE_ENDIAN like on FreeBSD. This fixes:
* issue #143
* issue #198
* issue #249
* Switch from <cstdatomic> to <atomic>. The former never made it into the
standard and doesn't exist in modern gcc versions at all. The later contains
everything that leveldb was using from the former.
This problem was noticed when porting to Portable Native Client where no memory
barrier is defined. The fact that <cstdatomic> is missing normally goes
unnoticed since memory barriers are defined for most architectures.
* Make Hash() treat its input as unsigned. Before this change LevelDB files
from platforms with different signedness of char were not compatible. This
change fixes: issue #243
* Verify checksums of index/meta/filter blocks when paranoid_checks set.
* Invoke all tools for iOS with xcrun. (This was causing problems with the new
XCode 5.1.1 image on pulse.)
* include <sys/stat.h> only once, and fix the following linter warning:
"Found C system header after C++ system header"
* When encountering a corrupted table file, return Status::Corruption instead of
Status::InvalidArgument.
* Support cygwin as build platform, patch is from https://code.google.com/p/leveldb/issues/detail?id=188
* Fix typo, merge patch from https://code.google.com/p/leveldb/issues/detail?id=159
* Fix typos and comments, and address the following two issues:
* issue #166
* issue #241
* Add missing db synchronize after "fillseq" in the benchmark.
* Removed unused variable in SeekRandom: value (issue #201)
- Cleanup: delete unused IntSetToString
It was added in http://cr/19491949 (and was referenced at the time).
The last reference was removed in http://cr/19507363.
This fixes warning/error with pre-release crosstoolv18:
'std::string leveldb::{anonymous}::IntSetToString(const std::set<long unsigned int>&)' defined but not used [-Werror=unused-function]
- Added arm64 and and armv7s to IOS build as suggested on leveldb mailing list.
- Changed local variable type from int to size_t
This eliminates compiler warning/error and resolves
https://code.google.com/p/leveldb/issues/detail?id=140
- Make Log::Reader not report a corruption when the last record in a
log file is truncated.
- Fix issue 224: variable created but not utilized.
- Remove comment that referenced a removed feature.
- switched from mmap based writing to simpler stdio based writing. Has a
minor impact (0.5 microseconds) on microbenchmarks for asynchronous
writes. Synchronous writes speed up from 30ms to 10ms on linux/ext4.
Should be much more reliable on diverse platforms.
- compaction errors now immediately put the database into a read-only
mode (until it is re-opened). As a downside, a disk going out of
space and then space being created will require a re-open to recover
from, whereas previously that would happen automatically. On the
plus side, many corruption possibilities go away.
- force the DB to enter an error-state so that all future writes fail
when a synchronous log write succeeds but the sync fails.
- repair now regenerates sstables that exhibit problems
- fix issue 218 - Use native memory barriers on OSX
- fix issue 212 - QNX build is broken
- fix build on iOS with xcode 5
- make tests compile and pass on windows
Fix issues 200, 201
Also,
* Fix link to bigtable paper in docs.
* New sstables will have the file extension .ldb. .sst files will
continue to be recognized.
* When building for iOS, use xcrun to execute the compiler. This may
affect issue 177.
Fix issues 77, 87, 182, 190.
Additionally, fix the bug described in
https://groups.google.com/d/msg/leveldb/yL6h1mAOc20/vLU64RylIdMJ
where a large contiguous keyspace of deleted data was not getting
compacted.
Also fix a bug where options.max_open_files was not getting clamped
properly.
Fixes issues
147 - thanks feniksgordonfreeman
153
156
166
Additionally,
* Remove calls to exit(1).
* Fix unused-variable warnings from clang.
* Fix possible overflow error related to num_restart value >= (2^32/4).
* Add leveldbutil to .gitignore.
* Add better log messages when Write is stalled on a compaction.
Details:
* Fix shared library building.
* Reorganize linking commands so flags like --as-needed can be passed.
* C binding exports version numbers.
* Fix small typos in documention.
Highlights
----------
Mmap at most 1000 files on Posix to improve performance for large databases.
Support for more architectures (thanks to Alexander K.)
Building and porting
--------------------
HP/UX support (issue 126)
AtomicPointer for ia64 (issue 123)
Sparc v9 support (issue 124)
Atomic ops for powerpc
Use -fno-builtin-memcmp only when using g++
Simplify IOS build rules (issue 114)
Use CXXFLAGS instead of CFLAGS when invoking C++ compiler (issue 118)
Fix snappy shared library problem (issue 94)
Fix shared library installation path regression
Endian-ness detection tweak for FreeBSD
Bug fixes
---------
Stop ignoring FLAGS_open_files in db_bench
Make bloom test behavior agnostic to endian-ness
Performance
-----------
Limit number of mmapped files to 1000 to improve perf for large dbs
Do not delay for 1 second on shutdown path (issue 125)
Misc
----
Make InMemoryEnv return a no-op logger
C binding now has a wrapper for free (issue 117)
Add thread-safety annotations
Added an in-process lock table (issue 120)
Make RandomAccessFile and SequentialFile non-copyable
various platforms; improve android port speed.
Avoid static initializer by using a new portability interface for
thread-safe lazy initialization. Custom ports will need to be
extended to implement InitOnce/OnceType/LEVELDB_ONCE_INIT.
Fix endian-ness detection (fixes Powerpc builds).
Build related fixes:
- Support platforms that have unversioned shared libraries.
- Fix IOS build rules.
Android improvements
- Speed up atomic pointers
- Share more code with port_posix.
Do not spin in a tight loop attempting compactions if the file system
is inaccessible (e.g., if kerberos tickets have expired or if it is out
of space).
In particular, we add a new FilterPolicy class. An instance
of this class can be supplied in Options when opening a
database. If supplied, the instance is used to generate
summaries of keys (e.g., a bloom filter) which are placed in
sstables. These summaries are consulted by DB::Get() so we
can avoid reading sstable blocks that are guaranteed to not
contain the key we are looking for.
This change provides one implementation of FilterPolicy
based on bloom filters.
Other changes:
- Updated version number to 1.4.
- Some build tweaks.
- C binding for CompactRange.
- A few more benchmarks: deleteseq, deleterandom, readmissing, seekrandom.
- Minor .gitignore update.
- Pass system's values of CFLAGS,LDFLAGS.
Don't override OPT if it's already set.
Original patch by Alessio Treglia <alessio@debian.org>:
http://code.google.com/p/leveldb/issues/detail?id=27#c6
- Remove 1 exit time destructor from leveldb.
See http://crbug.com/101600
- Fix problem where sstable building code would pass an
internal key to the user comparator.
(Sync with uptream at 25436817.)
- Replace raw slice comparison with a call to user comparator.
Added test for custom comparators.
- Fix end of namespace comments.
- Fixed bug in picking inputs for a level-0 compaction.
When finding overlapping files, the covered range may expand
as files are added to the input set. We now correctly expand
the range when this happens instead of continuing to use the
old range. For example, suppose L0 contains files with the
following ranges:
F1: a .. d
F2: c .. g
F3: f .. j
and the initial compaction target is F3. We used to search
for range f..j which yielded {F2,F3}. However we now expand
the range as soon as another file is added. In this case,
when F2 is added, we expand the range to c..j and restart the
search. That picks up file F1 as well.
This change fixes a bug related to deleted keys showing up
incorrectly after a compaction as described in Issue 44.
(Sync with upstream @25072954)
- Added DB::CompactRange() method.
Changed manual compaction code so it breaks up compactions of
big ranges into smaller compactions.
Changed the code that pushes the output of memtable compactions
to higher levels to obey the grandparent constraint: i.e., we
must never have a single file in level L that overlaps too
much data in level L+1 (to avoid very expensive L-1 compactions).
Added code to pretty-print internal keys.
- Fixed bug where we would not detect overlap with files in
level-0 because we were incorrectly using binary search
on an array of files with overlapping ranges.
Added "leveldb.sstables" property that can be used to dump
all of the sstables and ranges that make up the db state.
- Removing post_write_snapshot support. Email to leveldb mailing
list brought up no users, just confusion from one person about
what it meant.
- Fixing static_cast char to unsigned on BIG_ENDIAN platforms.
Fixes Issue 35 and Issue 36.
- Comment clarification to address leveldb Issue 37.
- Change license in posix_logger.h to match other files.
- A build problem where uint32 was used instead of uint32_t.
Sync with upstream @24408625
- Fix bug in Get: when it triggers a compaction, it could sometimes
mark the compaction with the wrong level (if there was a gap
in the set of levels examined for the Get).
- Do not hold mutex while writing to the log file or to the
MANIFEST file.
Added a new benchmark that runs a writer thread concurrently with
reader threads.
Percentiles
------------------------------
micros/op: avg median 99 99.9 99.99 99.999 max
------------------------------------------------------
before: 42 38 110 225 32000 42000 48000
after: 24 20 55 65 130 1100 7000
- Fixed race in optimized Get. It should have been using the
pinned memtables, not the current memtables.
git-svn-id: https://leveldb.googlecode.com/svn/trunk@50 62dab493-f737-651d-591e-8d6aee1b9529
- Fix for issue 33 (non-null-terminated result from
leveldb_property_value())
- Support for running multiple instances of a benchmark in parallel.
- Reduce lock contention on Get():
(1) Do not hold the lock while searching memtables.
(2) Shard block and table caches 16-ways.
Benchmark for evaluating this change:
$ db_bench --benchmarks=fillseq1,readrandom --threads=$n
(fillseq1 is a small hack to make sure fillseq runs once regardless
of number of threads specified on the command line).
git-svn-id: https://leveldb.googlecode.com/svn/trunk@49 62dab493-f737-651d-591e-8d6aee1b9529
- Fix bug in Iterator::Prev where it would return the wrong key.
Fixes issues 29 and 30.
- Added a tweak to testharness to allow running just some tests.
- Fixing two minor documentation errors based on issues 28 and 25.
- Cleanup; fix namespaces of export-to-C code.
Also fix one "const char*" vs "char*" mismatch.
git-svn-id: https://leveldb.googlecode.com/svn/trunk@48 62dab493-f737-651d-591e-8d6aee1b9529
- Added a C binding for LevelDB.
May be useful as a stable ABI that can be used by
programs that keep leveldb in a shared library,
or for JNI API.
- Replaced SQLite's readseq benchmark to a more efficient version.
SQLite readseq speeds increased by about a factor of 2x
from the previous version. Also updated benchmark page to
reflect readseq speed up.
git-svn-id: https://leveldb.googlecode.com/svn/trunk@46 62dab493-f737-651d-591e-8d6aee1b9529
- Removed one copy of an uncompressed block contents changing
the signature of Snappy_Uncompress() so it uncompresses into a
flat array instead of a std::string.
Speeds up readrandom ~10%.
- Instead of a combination of Env/WritableFile, we now have a
Logger interface that can be easily overridden applications
that want to supply their own logging.
- Separated out the gcc and Sun Studio parts of atomic_pointer.h
so we can use 'asm', 'volatile' keywords for Sun Studio.
git-svn-id: https://leveldb.googlecode.com/svn/trunk@39 62dab493-f737-651d-591e-8d6aee1b9529
