This CL removes AtomicPointer from leveldb's port interface. Its usage is replaced with std::atomic<> from the C++11 standard library.
AtomicPointer was used to wrap flags, numbers, and pointers, so its instances are replaced with std::atomic<bool>, std::atomic<int>, std::atomic<size_t> and std::atomic<Node*>.
This CL does not revise the memory ordering. AtomicPointer's methods are replaced mechanically with their std::atomic equivalents, even when the underlying usage is incorrect. (Example: DBImpl::has_imm_ is written using release stores, even though it is always read using relaxed ordering.) Revising the memory ordering is left for future CLs.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=237865146
This is not an API-breaking change, because it reduces the API that the
leveldb embedder must implement. The project will build just fine
against ports that still implement InitOnce.
C++11 guarantees thread-safe initialization of static variables inside
functions. This is a more restricted form of std::call_once or
pthread_once_t (e.g., single call site), so the compiler might be able
to generate better code [1]. Equally important, having less code in
port_example.h makes it easier to port to other platforms.
Due to the change above, this CL introduces a new approach for storing
the singleton BytewiseComparatorImpl instance returned by
BytewiseComparator(). The new approach avoids a dynamic memory
allocation, which eliminates the false positive from LeakSanitizer
reported in https://github.com/google/leveldb/issues/200
[1] https://stackoverflow.com/a/27206650/
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=212348004
The porting layer implements threading primitives: atomic pointers,
condition variables, mutexes, thread-safe initialization. These are all
specified in C++11, so the reference open source port implementation can
become platform-independent.
The porting layer will remain in place to allow the use of other
implementations with more features, such as the built-in deadlock
detection in abseil's Mutex.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=193245934
This is an accidental leftover from the CMake migration. The macro has
been replaced with LEVELDB_IS_BIG_ENDIAN.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=192364918
External linkage is the default for function declarations in C++.
This also fixes ClangTidy errors generated by removing the "extern"
keyword as described above.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=188730416
This follows the general naming convention for preprocessor macros used
to detect feature (library / header file / symbol) presence.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171184641
CL 170738066 removed all instances of fread_unlocked, fwrite_unlocked
and fflush_unlocked calls from the codebase, so the feature detection
can be removed as well.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=171154269
Use __APPLE__ instead of OS_MACOS when testing for the Apple platform and
remove the latter symbol from the BUILD file. This fixes incompatibility issues
when using the library on an Apple device.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=162958094
This change authored by vadimskipin and submitted via:
https://github.com/google/leveldb/pull/309
Changes made to support iOS builds and other architectures
without support for SSE 4.2.
db_bench reports original crc32 speed at:
crc32c : 3.610 micros/op; 1082.0 MB/s (4K per op)
with this change performance has increased to:
crc32c : 0.843 micros/op; 4633.6 MB/s (4K per op)
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=148694935
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)
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).
- LevelDB patch for FreeBSD. This resolves Issue 22.
Contributed by dforsythe (thanks!).
- Removing Chromium-specific files.
They are now going to live in the Chromium repository.
- Adding a benchmark page comparing LevelDB performance
to SQLite and Kyoto Cabinet's TreeDB, along with
code to generate the benchmarks.
Thanks to Kevin Tseng for compiling the benchmarks,
and Scott Hess and Mikio Hirabayashi for their
help and advice.
git-svn-id: https://leveldb.googlecode.com/svn/trunk@40 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
Change atomic_pointer.h to prefer a memory barrier based
implementation over a <cstdatomic> based implementation for
the following reasons:
(1) On a x86-32-bit gcc-4.4 build, <ctdatomic> was corrupting
the AtomicPointer.
(2) On a x86-64-bit gcc build, a <ctstdatomic> based acquire-load
takes ~15ns as opposed to the ~1ns for a memory-barrier
based implementation.
Fixes issue 9 (corruption_test fails)
http://code.google.com/p/leveldb/issues/detail?id=9
Fixes issue 16 (CorruptionTest.MissingDescriptor fails)
http://code.google.com/p/leveldb/issues/detail?id=16
git-svn-id: https://leveldb.googlecode.com/svn/trunk@36 62dab493-f737-651d-591e-8d6aee1b9529
This revision adds two major changes:
1. build_detect_platform which generates build_config.mk
with platform-dependent flags for the build process
2. /port/atomic_pointer.h with anAtomicPointerimplementation
for platforms without <cstdatomic>
Some of this code is loosely based on patches submitted to the
LevelDB mailing list at https://groups.google.com/forum/#!forum/leveldb
Tip of the hat to Dave Smith and Edouard A, who both sent patches.
The presence of Snappy (http://code.google.com/p/snappy/) and
cstdatomic are now both detected in the build_detect_platform
script (1.) which gets executing during make.
For (2.), instead of broadly importing atomicops_* from Chromium or
the Google performance tools, we chose to just implement AtomicPointer
and the limited atomic load and store operations it needs.
This resulted in much less code and fewer files - everything is
contained in atomic_pointer.h.
git-svn-id: https://leveldb.googlecode.com/svn/trunk@34 62dab493-f737-651d-591e-8d6aee1b9529
- Implemented Get() directly instead of building on top of a full
merging iterator stack. This speeds up the "readrandom" benchmark
by up to 15-30%.
- Fixed an opensource compilation problem.
Added --db=<name> flag to control where the database is placed.
- Automatically compact a file when we have done enough
overlapping seeks to that file.
- Fixed a performance bug where we would read from at least one
file in a level even if none of the files overlapped the key
being read.
- Makefile fix for Mac OSX installations that have XCode 4 without XCode 3.
- Unified the two occurrences of binary search in a file-list
into one routine.
- Found and fixed a bug where we would unnecessarily search the
last file when looking for a key larger than all data in the
level.
- A fix to avoid the need for trivial move compactions and
therefore gets rid of two out of five syncs in "fillseq".
- Removed the MANIFEST file write when switching to a new
memtable/log-file for a 10-20% improvement on fill speed on ext4.
- Adding a SNAPPY setting in the Makefile for folks who have
Snappy installed. Snappy compresses values and speeds up writes.
git-svn-id: https://leveldb.googlecode.com/svn/trunk@32 62dab493-f737-651d-591e-8d6aee1b9529
* env_chromium.cc should not export symbols.
* Fix MSVC warnings.
* Removed large value support.
* Fix broken reference to documentation file
git-svn-id: https://leveldb.googlecode.com/svn/trunk@24 62dab493-f737-651d-591e-8d6aee1b9529
costan
scrubbed
Chris Mumford
Sanjay Ghemawat
David Grogan
gabor@google.com
dgrogan@chromium.org
jorlow@chromium.org