Summary:
It would appear our unit tests make use of code from ldb_cmd,
and don't always require a valid database handle. D6855 was not aware
db_ could sometimes be NULL for such commands, and so it broke
reduce_levels_test.
This moves the check elsewhere to (at least) fix the 'ldb dump' case of
segfaulting when it couldn't open a database.
Test Plan: make check
Reviewers: dhruba
Reviewed By: dhruba
CC: leveldb
Differential Revision: https://reviews.facebook.net/D6903
Summary:
Link statically against snappy, using the gvfs one for facebook
environments, and the bundled one otherwise.
In addition, fix a few minor segfaults in ldb when it couldn't open the
database, and update .gitignore to include a few other build artifacts.
Test Plan: make check
Reviewers: dhruba
Reviewed By: dhruba
CC: leveldb
Differential Revision: https://reviews.facebook.net/D6855
Summary:
The compaction process takes some files from LevelK and
merges it into LevelK+1. The number of files it picks from
LevelK was capped such a way that the total amount of
data picked does not exceed the maxfilesize of that level.
This essentially meant that only one file from LevelK
is picked for a single compaction.
For bulkloads, we would like to take many many file from
LevelK and compact them using a single compaction run.
This patch introduces a option called the 'source_compaction_factor'
(similar to expanded_compaction_factor). It is a multiplier
that is multiplied by the maxfilesize of that level to arrive
at the limit that is used to throttle the number of source
files from LevelK. For bulk loads, set source_compaction_factor
to a very high number so that multiple files from the same
level are picked for compaction in a single compaction.
The default value of source_compaction_factor is 1, so that
we can keep backward compatibilty with existing compaction semantics.
Test Plan: make clean check
Reviewers: emayanke, sheki
Reviewed By: emayanke
CC: leveldb
Differential Revision: https://reviews.facebook.net/D6867
Summary:
This option is needed for fast bulk uploads. The goal is to load
all the data into files in L0 without any interference from
background compactions.
Test Plan: make clean check
Reviewers: sheki
Reviewed By: sheki
CC: leveldb
Differential Revision: https://reviews.facebook.net/D6849
Summary:
StringStream.clear() does not clear the stream. It sets some flags.
Who knew? Fixing that is not printing the stuff again and again.
Test Plan: ran it on a local db
Reviewers: dhruba, emayanke
Reviewed By: dhruba
Differential Revision: https://reviews.facebook.net/D6795
Summary:
There are applications that operate on multiple leveldb instances.
These applications will like to pass in an opaque type for each
leveldb instance and this type should be passed back to the application
with every invocation of the CompactionFilter api.
Test Plan: Enehanced unit test for opaque parameter to CompactionFilter.
Reviewers: heyongqiang
Reviewed By: heyongqiang
CC: MarkCallaghan, sheki, emayanke
Differential Revision: https://reviews.facebook.net/D6711
Summary:
I changed the reduce_num_levels logic to avoid "compactRange()" call if the current number of levels in use (levels that contain files) is smaller than the new num of levels.
And that change breaks the assert in reduce_levels_test
Test Plan: run reduce_levels_test
Reviewers: dhruba, MarkCallaghan
Reviewed By: dhruba
CC: emayanke, sheki
Differential Revision: https://reviews.facebook.net/D6651
Summary:
make clean check OPT=-g fails
leveldb::DBStatistics::getTickerCount(leveldb::Tickers)’:
./db/db_statistics.h:34: error: ‘MAX_NO_TICKERS’ was not declared in this scope
util/ldb_cmd.cc:255: warning: left shift count >= width of type
Test Plan:
make clean check OPT=-g
Reviewers:
CC:
Task ID: #
Blame Rev:
Summary:
disable size compaction in ldb reduce_levels, this will avoid compactions rather than the manual comapction,
added --compression=none|snappy|zlib|bzip2 and --file_size= per-file size to ldb reduce_levels command
Test Plan: run ldb
Reviewers: dhruba, MarkCallaghan
Reviewed By: dhruba
CC: sheki, emayanke
Differential Revision: https://reviews.facebook.net/D6597
Summary:
The default compilation process now uses "-Wall" to compile.
Fix all compilation error generated by gcc.
Test Plan: make all check
Reviewers: heyongqiang, emayanke, sheki
Reviewed By: heyongqiang
CC: MarkCallaghan
Differential Revision: https://reviews.facebook.net/D6525
Summary:
There are certain use-cases where the application intends to
delete older keys aftre they have expired a certian time period.
One option for those applications is to periodically scan the
entire database and delete appropriate keys.
A better way is to allow the application to hook into the
compaction process. This patch allows the application to set
a method callback for every key that is being compacted. If
this method returns true, then the key is not preserved in
the output of the compaction.
Test Plan:
This is mostly to preview the proposed new public api.
Since it is a public api, please do due diligence on reviewing it.
I will be writing test cases for this api in mynext version of
this patch.
Reviewers: MarkCallaghan, heyongqiang
Reviewed By: heyongqiang
CC: sheki, adsharma
Differential Revision: https://reviews.facebook.net/D6285
Summary: as subject.
Test Plan: manually test it, will add a testcase
Reviewers: dhruba, MarkCallaghan
Differential Revision: https://reviews.facebook.net/D6345
Summary: Leveldb currently uses windowBits=-14 while using zlib compression.(It was earlier 15). This makes the setting configurable. Related changes here: https://reviews.facebook.net/D6105
Test Plan: make all check
Reviewers: dhruba, MarkCallaghan, sheki, heyongqiang
Differential Revision: https://reviews.facebook.net/D6393
Summary:
as subject
Test Plan:
run db_bench and db_test
Reviewers: dhruba
Reviewed By: dhruba
Differential Revision: https://reviews.facebook.net/D6111
Summary:
The leveldb API is enhanced to support different compression algorithms at
different levels.
This adds the option min_level_to_compress to db_bench that specifies
the minimum level for which compression should be done when
compression is enabled. This can be used to disable compression for levels
0 and 1 which are likely to suffer from stalls because of the CPU load
for memtable flushes and (L0,L1) compaction. Level 0 is special as it
gets frequent memtable flushes. Level 1 is special as it frequently
gets all:all file compactions between it and level 0. But all other levels
could be the same. For any level N where N > 1, the rate of sequential
IO for that level should be the same. The last level is the
exception because it might not be full and because files from it are
not read to compact with the next larger level.
The same amount of time will be spent doing compaction at any
level N excluding N=0, 1 or the last level. By this standard all
of those levels should use the same compression. The difference is that
the loss (using more disk space) from a faster compression algorithm
is less significant for N=2 than for N=3. So we might be willing to
trade disk space for faster write rates with no compression
for L0 and L1, snappy for L2, zlib for L3. Using a faster compression
algorithm for the mid levels also allows us to reclaim some cpu
without trading off much loss in disk space overhead.
Also note that little is to be gained by compressing levels 0 and 1. For
a 4-level tree they account for 10% of the data. For a 5-level tree they
account for 1% of the data.
With compression enabled:
* memtable flush rate is ~18MB/second
* (L0,L1) compaction rate is ~30MB/second
With compression enabled but min_level_to_compress=2
* memtable flush rate is ~320MB/second
* (L0,L1) compaction rate is ~560MB/second
This practicaly takes the same code from https://reviews.facebook.net/D6225
but makes the leveldb api more general purpose with a few additional
lines of code.
Test Plan: make check
Differential Revision: https://reviews.facebook.net/D6261
Summary:
Adds a method that returns the score for the next level that most
needs compaction. That method is then used by db_bench to rate limit threads.
Threads are put to sleep at the end of each stats interval until the score
is less than the limit. The limit is set via the --rate_limit=$double option.
The specified value must be > 1.0. Also adds the option --stats_per_interval
to enable additional metrics reported every stats interval.
Task ID: #
Blame Rev:
Test Plan:
run db_bench
Revert Plan:
Database Impact:
Memcache Impact:
Other Notes:
EImportant:
- begin *PUBLIC* platform impact section -
Bugzilla: #
- end platform impact -
Reviewers: dhruba
Reviewed By: dhruba
Differential Revision: https://reviews.facebook.net/D6243
Summary: Enable LevelDb to create a new log file if current log file is too large.
Test Plan:
Write a script and manually check the generated info LOG.
Task ID: 1803577
Blame Rev:
Reviewers: dhruba, heyongqiang
Reviewed By: heyongqiang
CC: zshao
Differential Revision: https://reviews.facebook.net/D6003
Summary:
The parameter delete_obsolete_files_period_micros controls the
periodicity of deleting obsolete files. db_bench was reading in
this parameter intoa local variable called 'l' but was incorrectly
using another local variable called 'n' while setting it in the
db.options data structure.
This patch also logs the value of delete_obsolete_files_period_micros
in the LOG file at db startup time.
I am hoping that this will improve the overall write throughput drastically.
Test Plan: run db_bench
Reviewers: MarkCallaghan, heyongqiang
Reviewed By: MarkCallaghan
Differential Revision: https://reviews.facebook.net/D6099
published in https://reviews.facebook.net/D5997.
Summary:
This patch allows compaction to occur in multiple background threads
concurrently.
If a manual compaction is issued, the system falls back to a
single-compaction-thread model. This is done to ensure correctess
and simplicity of code. When the manual compaction is finished,
the system resumes its concurrent-compaction mode automatically.
The updates to the manifest are done via group-commit approach.
Test Plan: run db_bench
Summary:
The method DeleteObsolete files is a very costly methind, especially
when the number of files in a system is large. It makes a list of
all live-files and then scans the directory to compute the diff.
By default, this method is executed after every compaction run.
This patch makes it such that DeleteObsolete files is never
invoked twice within a configured period.
Test Plan: run all unit tests
Reviewers: heyongqiang, MarkCallaghan
Reviewed By: MarkCallaghan
Differential Revision: https://reviews.facebook.net/D6045
Summary:
Each assoc is identified by (id1, assocType). This is the rowkey.
Each row has a read/write rowlock. There is statically allocated array
of 2000 read/write locks. A rowkey is murmur-hashed to one of the
read/write locks.
assocPut and assocDelete acquires the rowlock in Write mode.
The key-updates are done within the rowlock with a atomic nosync
batch write to leveldb. Then the rowlock is released and
a write-with-sync is done to sync leveldb transaction log.
Test Plan: added unit test
Reviewers: heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D5859
Summary:
We have seen that reading data via the pread call (instead of
mmap) is much faster on Linux 2.6.x kernels. This patch makes
an equivalent option to switch off mmaps for the write path
as well.
db_bench --mmap_write=0 will use write() instead of mmap() to
write data to a file.
This change is backward compatible, the default
option is to continue using mmap for writing to a file.
Test Plan: "make check all"
Differential Revision: https://reviews.facebook.net/D5781
Summary:
Implement ReadWrite locks for leveldb. These will be helpful
to implement a read-modify-write operation (e.g. atomic increments).
Test Plan: does not modify any existing code
Reviewers: heyongqiang
Reviewed By: heyongqiang
CC: MarkCallaghan
Differential Revision: https://reviews.facebook.net/D5787
Summary: Print the block cache size in the LOG.
Test Plan: run db_bench and look at LOG. This is helpful while I was debugging one use-case.
Reviewers: heyongqiang, MarkCallaghan
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D5739
Summary:
The GetLiveFiles() api lists the set of sst files and the current
MANIFEST file. But the database continues to append new data to the
MANIFEST file even when the application is backing it up to the
backup location. This means that the database-version that is
stored in the MANIFEST FILE in the backup location
does not correspond to the sst files returned by GetLiveFiles.
This API adds a new parameter to GetLiveFiles. This new parmeter
returns the current size of the MANIFEST file.
Test Plan: Unit test attached.
Reviewers: heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D5631
Summary:
The background threads are necessary for compaction.
For slower storage, it might be necessary to have more than
one compaction thread per DB. This patch allows creating
a configurable number of worker threads.
The default reamins at 1 (to maintain backward compatibility).
Test Plan:
run all unit tests. changes to db-bench coming in
a separate patch.
Reviewers: heyongqiang
Reviewed By: heyongqiang
CC: MarkCallaghan
Differential Revision: https://reviews.facebook.net/D5559
Summary:
as subject. This diff should be good for benchmarking.
will send another diff to make it better in the case the seek compaction is enable.
In that coming diff, will not count a seek if the bloomfilter filters.
Test Plan: build
Reviewers: dhruba, MarkCallaghan
Reviewed By: MarkCallaghan
Differential Revision: https://reviews.facebook.net/D5481
Summary:
as subject. this can be used for benchmarking.
If we want it for some cases, we can do more changes to make this part of the option.
Test Plan: db_test
Reviewers: dhruba
CC: MarkCallaghan
Differential Revision: https://reviews.facebook.net/D5451
Summary:
Reads via mmap on concurrent workloads are much slower than pread.
For example on a 24-core server with storage that can do 100k IOPS or more
I can get no more than 10k IOPS with mmap reads and 32+ threads.
Test Plan: db_bench benchmarks
Reviewers: dhruba, heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D5433
Summary:
Ability to switch off filesystem read-aheads. This change is
backward-compatible: the default setting is to allow file
system read-aheads.
Test Plan: run benchmarks
Reviewers: heyongqiang, adsharma
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D5391
Summary:
When posix_fadvise(offset, offset) is usedm it frees up only those
pages in that specified range. But the filesystem could have done some
read-aheads and those get cached in the OS cache.
Do not cache readahead-pages in the OS cache.
Test Plan: run db_bench benchmark.
Reviewers: vamsi, heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D5379
Summary: added a new option db_log_dir, which points the log dir. Inside that dir, in order to make log names unique, the log file name is prefixed with the leveldb data dir absolute path.
Test Plan: db_test
Reviewers: dhruba
Reviewed By: dhruba
Differential Revision: https://reviews.facebook.net/D5205
Summary:
Clean up compiler warnings generated by -Wall option.
make clean all OPT=-Wall
This is a pre-requisite before making a new release.
Test Plan: compile and run unit tests
Reviewers: heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D5019
Summary:
The numbers of shards that the block cache is divided into is
configurable. However, if the user specifies that he/she wants
the block cache to be divided into more than 2**20 pieces, then
the system will rey to allocate a huge array of that size) that
could fail.
It is better to limit the sharding of the block cache to an
upper bound. The default sharding is 16 shards (i.e. 2**4)
and the maximum is now 2 million shards (i.e. 2**20).
Also, fixed a bug with the LRUCache where the numShardBits
should be a private member of the LRUCache object rather than
a static variable.
Test Plan:
run db_bench with --cache_numshardbits=64.
Task ID: #
Blame Rev:
Reviewers: heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D5013
Summary:
Introduce a new method Env->Fsync() that issues fsync (instead of fdatasync).
This is needed for data durability when running on ext3 filesystems.
Added options to the benchmark db_bench to generate performance numbers
with either fsync or fdatasync enabled.
Cleaned up Makefile to build leveldb_shell only when building the thrift
leveldb server.
Test Plan: build and run benchmark
Reviewers: heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D4911
Summary: Log the open-options to the LOG. Use options_ instead of options because SanitizeOptions could modify the max_file_open limit.
Test Plan: num db_bench
Reviewers: heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D4833
Summary: Record the version of the source that we are compiling. We keep a record of the git revision in util/version.cc. This source file is then built as a regular source file as part of the compilation process. One can run "strings executable_filename | grep _build_" to find the version of the source that we used to build the executable file.
Test Plan: none
Differential Revision: https://reviews.facebook.net/D4785
Summary:
as subject.
A new log is written to scribe via thrift client when a new db is opened and when there is
a compaction.
a new option var scribe_log_db_stats is added.
Test Plan: manually checked using command "ptail -time 0 leveldb_deploy_stats"
Reviewers: dhruba
Differential Revision: https://reviews.facebook.net/D4659
Summary:
The fcntl call cannot detect lock conflicts when invoked multiple times
from the same thread.
Use a static lockedFile Set to record the paths that are locked.
A lockfile request checks to see if htis filename already exists in
lockedFiles, if so, then it triggers an error. Otherwise, it inserts
the filename in the lockedFiles Set.
A unlock file request verifies that the filename is in the lockedFiles
set and removes it from lockedFiles set.
Test Plan: unit test attached
Reviewers: heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D4755
My change in this patch is to make the Hash code that is used for blooms to be confgurable. In fact,
one can specify a modified HashCode that inspects only parts of the Key to generate the Hash (used
by booms).
Test Plan: none
Differential Revision: https://reviews.facebook.net/D4059
Summary:
First draft.
Unit tests pass.
Test Plan: unit tests attached
Reviewers: heyongqiang
Reviewed By: heyongqiang
Differential Revision: https://reviews.facebook.net/D3969
Summary:
This speeds up CRC computation significantly on
hardware that supports it. Enabled via -msse4.
Note: the binary won't be usable on older CPUs
that don't support the instruction.
Test Plan: crc32c_test
Reviewers: dhruba
Reviewed By: dhruba
Differential Revision: https://reviews.facebook.net/D3201
Summary:
Some code reorganization in-preparation for replacing with a hardware
instruction.
* Use u64 for some of the key types
* Use an ALIGN macro so code is easier to read
Test Plan: crc32c_test
Reviewers: dhruba
Reviewed By: dhruba
Differential Revision: https://reviews.facebook.net/D3135
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 GCC -Wshadow warnings in LevelDB's public header files,
reported by Dustin.
Add in-memory Env implementation (helpers/memenv/*).
This enables users to create LevelDB databases in-memory.
Initialize ShardedLRUCache::last_id_ to zero.
This fixes a Valgrind warning.
(Also delete port/sha1_* which were removed upstream some time ago.)
- 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
- 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
- LevelDB patch for Sun Studio
Based on a patch submitted by Theo Schlossnagle - thanks!
This fixes Issue 17.
- Fix a couple of test related memory leaks.
git-svn-id: https://leveldb.googlecode.com/svn/trunk@38 62dab493-f737-651d-591e-8d6aee1b9529
Slight tweak to the no-overlap optimization: only push to
level 2 to reduce the amount of wasted space when the same
small key range is being repeatedly overwritten.
Fix for Issue 18: Avoid failure on Windows by avoiding
deletion of lock file until the end of DestroyDB().
Fix for Issue 19: Disregard sequence numbers when checking for
overlap in sstable ranges. This fixes issue 19: when writing
the same key over and over again, we would generate a sequence
of sstables that were never merged together since their sequence
numbers were disjoint.
Don't ignore map/unmap error checks.
Miscellaneous fixes for small problems Sanjay found while diagnosing
issue/9 and issue/16 (corruption_testr failures).
- log::Reader reports the record type when it finds an unexpected type.
- log::Reader no longer reports an error when it encounters an expected
zero record regardless of the setting of the "checksum" flag.
- Added a missing forward declaration.
- Documented a side-effects of larger write buffer sizes
(longer recovery time).
git-svn-id: https://leveldb.googlecode.com/svn/trunk@37 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
* Patch LevelDB to build for OSX and iOS
* Fix race condition in memtable iterator deletion.
* Other small fixes.
git-svn-id: https://leveldb.googlecode.com/svn/trunk@29 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
