Commit Graph

3 Commits

Author SHA1 Message Date
Jim Paton 74781a0c49 Add three new MemTableRep's
Summary:
This patch adds three new MemTableRep's: UnsortedRep, PrefixHashRep, and VectorRep.

UnsortedRep stores keys in an std::unordered_map of std::sets. When an iterator is requested, it dumps the keys into an std::set and iterates over that.

VectorRep stores keys in an std::vector. When an iterator is requested, it creates a copy of the vector and sorts it using std::sort. The iterator accesses that new vector.

PrefixHashRep stores keys in an unordered_map mapping prefixes to ordered sets.

I also added one API change. I added a function MemTableRep::MarkImmutable. This function is called when the rep is added to the immutable list. It doesn't do anything yet, but it seems like that could be useful. In particular, for the vectorrep, it means we could elide the extra copy and just sort in place. The only reason I haven't done that yet is because the use of the ArenaAllocator complicates things (I can elaborate on this if needed).

Test Plan:
make -j32 check
./db_stress --memtablerep=vector
./db_stress --memtablerep=unsorted
./db_stress --memtablerep=prefixhash --prefix_size=10

Reviewers: dhruba, haobo, emayanke

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D12117
2013-08-22 23:10:02 -07:00
Xing Jin 0f0a24e298 Make arena block size configurable
Summary:
Add an option for arena block size, default value 4096 bytes. Arena will allocate blocks with such size.

I am not sure about passing parameter to skiplist in the new virtualized framework, though I talked to Jim a bit. So add Jim as reviewer.

Test Plan:
new unit test, I am running db_test.

For passing paramter from configured option to Arena, I tried tests like:

  TEST(DBTest, Arena_Option) {
  std::string dbname = test::TmpDir() + "/db_arena_option_test";
  DestroyDB(dbname, Options());

  DB* db = nullptr;
  Options opts;
  opts.create_if_missing = true;
  opts.arena_block_size = 1000000; // tested 99, 999999
  Status s = DB::Open(opts, dbname, &db);
  db->Put(WriteOptions(), "a", "123");
  }

and printed some debug info. The results look good. Any suggestion for such a unit-test?

Reviewers: haobo, dhruba, emayanke, jpaton

Reviewed By: dhruba

CC: leveldb, zshao

Differential Revision: https://reviews.facebook.net/D11799
2013-07-31 12:42:23 -07:00
Jim Paton 52d7ecfc78 Virtualize SkipList Interface
Summary: This diff virtualizes the skiplist interface so that users can provide their own implementation of a backing store for MemTables. Eventually, the backing store will be responsible for its own synchronization, allowing users (and us) to experiment with different lockless implementations.

Test Plan:
make clean
make -j32 check
./db_stress

Reviewers: dhruba, emayanke, haobo

Reviewed By: dhruba

CC: leveldb

Differential Revision: https://reviews.facebook.net/D11739
2013-07-23 14:42:27 -07:00