Summary:
Currently, blocks which have more than one reference (ie referenced by something other than cache itself) are evicted from cache. This doesn't make much sense:
- blocks are still in RAM, so the RAM usage reported by the cache is incorrect
- if the same block is needed by another iterator, it will be loaded and decompressed again
This diff changes the reference counting scheme a bit. Previously, if the cache contained the block, this was accounted for in its refcount. After this change, the refcount is only used to track external references. There is a boolean flag which indicates whether or not the block is contained in the cache.
This diff also changes how LRU list is used. Previously, both hashtable and the LRU list contained all blocks. After this change, the LRU list contains blocks with the refcount==0, ie those which can be evicted from the cache.
Note that this change still allows for cache to grow beyond its capacity. This happens when all blocks are pinned (ie refcount>0). This is consistent with the current behavior. The cache's insert function never fails. I spent lots of time trying to make table_reader and other places work with the insert which might failed. It turned out to be pretty hard. It might really destabilize some customers, so finally, I decided against doing this.
table_cache_remove_scan_count_limit option will be unneeded after this change, but I will remove it in the following diff, if this one gets approved
Test Plan: Ran tests, made sure they pass
Reviewers: sdong, ljin
Differential Revision: https://reviews.facebook.net/D25503
Summary:
In some environment such as android, the c++ library does not have
std::to_string. This path adds rocksdb::ToString(), which wraps std::to_string
when std::to_string is not available, and implements std::to_string
in the other case.
Test Plan:
make dbg -j32
./db_test
make clean
make dbg OPT=-DOS_ANDROID -j32
./db_test
Reviewers: ljin, sdong, igor
Reviewed By: igor
Subscribers: dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D29181
Summary:
We need to turn on -Wshorten-64-to-32 for mobile. See D1671432 (internal phabricator) for details.
This diff turns on the warning flag and fixes all the errors. There were also some interesting errors that I might call bugs, especially in plain table. Going forward, I think it makes sense to have this flag turned on and be very very careful when converting 64-bit to 32-bit variables.
Test Plan: compiles
Reviewers: ljin, rven, yhchiang, sdong
Reviewed By: yhchiang
Subscribers: bobbaldwin, dhruba, leveldb
Differential Revision: https://reviews.facebook.net/D28689
Summary: Added a method that executes a callback on every cache entry.
Test Plan: added a unit test
Reviewers: haobo
Reviewed By: haobo
CC: leveldb, dhruba
Differential Revision: https://reviews.facebook.net/D18441
Summary: Compiling for iOS has by default turned on -Wmissing-prototypes, which causes rocksdb to fail compiling. This diff turns on -Wmissing-prototypes in our compile options and cleans up all functions with missing prototypes.
Test Plan: compiles
Reviewers: dhruba, haobo, ljin, sdong
Reviewed By: ljin
CC: leveldb
Differential Revision: https://reviews.facebook.net/D17649
Summary: make release complains signed unsigned comparison.
Test Plan: make release
Reviewers: kailiu
CC: leveldb
Differential Revision: https://reviews.facebook.net/D14661
Summary: This diff will help us to figure out the memory usage for the cache part.
Test Plan: added a new memory usage test for cache
Reviewers: haobo, sdong, dhruba
CC: leveldb
Differential Revision: https://reviews.facebook.net/D14559
Summary:
With this patch, when LRUCache.Insert() is called and the cache is full, it will first try to free up entries whose reference counter is 1 (would become 0 after remo\
ving from the cache). We do it in two passes, in the first pass, we only try to release those unreferenced entries. If we cannot free enough space after traversing t\
he first remove_scan_cnt_ entries, we start from the beginning again and remove those entries being used.
Test Plan: add two unit tests to cover the codes
Reviewers: dhruba, haobo, emayanke
Reviewed By: emayanke
CC: leveldb, emayanke, xjin
Differential Revision: https://reviews.facebook.net/D13377
Summary:
As title. Fix an lint error:
Lint: CppLint Error
Single-argument constructor 'Value(int v)' may inadvertently be used as a type conversion constructor. Prefix the function with the 'explicit' keyword to avoid this, or add an /* implicit */ comment to suppress this warning.
Test Plan: N/A
Reviewers: emayanke, haobo, dhruba
Reviewed By: emayanke
CC: leveldb
Differential Revision: https://reviews.facebook.net/D13401
Summary:
Change namespace from leveldb to rocksdb. This allows a single
application to link in open-source leveldb code as well as
rocksdb code into the same process.
Test Plan: compile rocksdb
Reviewers: emayanke
Reviewed By: emayanke
CC: leveldb
Differential Revision: https://reviews.facebook.net/D13287
Summary: Replace include/leveldb with include/rocksdb.
Test Plan:
make clean; make check
make clean; make release
Differential Revision: https://reviews.facebook.net/D12489
Summary:
1. The stock LRUCache nukes itself whenever the working set (the total number of entries not released by client at a certain time) is bigger than the cache capacity.
See https://our.dev.facebook.com/intern/tasks/?t=2252281
2. There's a bug in shard calculation leading to segmentation fault when only one shard is needed.
Test Plan: make check
Reviewers: dhruba, heyongqiang
Reviewed By: heyongqiang
CC: leveldb, zshao, sheki
Differential Revision: https://reviews.facebook.net/D9927
Summary:
Replace manual memory management with std::unique_ptr in a
number of places; not exhaustive, but this fixes a few leaks with file
handles as well as clarifies semantics of the ownership of file handles
with log classes.
Test Plan: db_stress, make check
Reviewers: dhruba
Reviewed By: dhruba
CC: zshao, leveldb, heyongqiang
Differential Revision: https://reviews.facebook.net/D8043
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
- 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)
- 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
