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Summary: A vector that leverages pre-allocated stack-based array to achieve better performance for array with small amount of items. Test Plan: Added tests for both correctness and performance Here is the performance benchmark between vector and autovector Please note that in the test "Creation and Insertion Test", the test case were designed with the motivation described below: * no element inserted: internal array of std::vector may not really get initialize. * one element inserted: internal array of std::vector must have initialized. * kSize elements inserted. This shows the most time we'll spend if we keep everything in stack. * 2 * kSize elements inserted. The internal vector of autovector must have been initialized. Note: kSize is the capacity of autovector ===================================================== Creation and Insertion Test ===================================================== created 100000 vectors: each was inserted with 0 elements total time elapsed: 128000 (ns) created 100000 autovectors: each was inserted with 0 elements total time elapsed: 3641000 (ns) created 100000 VectorWithReserveSizes: each was inserted with 0 elements total time elapsed: 9896000 (ns) ----------------------------------- created 100000 vectors: each was inserted with 1 elements total time elapsed: 11089000 (ns) created 100000 autovectors: each was inserted with 1 elements total time elapsed: 5008000 (ns) created 100000 VectorWithReserveSizes: each was inserted with 1 elements total time elapsed: 24271000 (ns) ----------------------------------- created 100000 vectors: each was inserted with 4 elements total time elapsed: 39369000 (ns) created 100000 autovectors: each was inserted with 4 elements total time elapsed: 10121000 (ns) created 100000 VectorWithReserveSizes: each was inserted with 4 elements total time elapsed: 28473000 (ns) ----------------------------------- created 100000 vectors: each was inserted with 8 elements total time elapsed: 75013000 (ns) created 100000 autovectors: each was inserted with 8 elements total time elapsed: 18237000 (ns) created 100000 VectorWithReserveSizes: each was inserted with 8 elements total time elapsed: 42464000 (ns) ----------------------------------- created 100000 vectors: each was inserted with 16 elements total time elapsed: 102319000 (ns) created 100000 autovectors: each was inserted with 16 elements total time elapsed: 76724000 (ns) created 100000 VectorWithReserveSizes: each was inserted with 16 elements total time elapsed: 68285000 (ns) ----------------------------------- ===================================================== Sequence Access Test ===================================================== performed 100000 sequence access against vector size: 4 total time elapsed: 198000 (ns) performed 100000 sequence access against autovector size: 4 total time elapsed: 306000 (ns) ----------------------------------- performed 100000 sequence access against vector size: 8 total time elapsed: 565000 (ns) performed 100000 sequence access against autovector size: 8 total time elapsed: 512000 (ns) ----------------------------------- performed 100000 sequence access against vector size: 16 total time elapsed: 1076000 (ns) performed 100000 sequence access against autovector size: 16 total time elapsed: 1070000 (ns) ----------------------------------- Reviewers: dhruba, haobo, sdong, chip Reviewed By: dhruba CC: leveldb Differential Revision: https://reviews.facebook.net/D14655
rocksdb: A persistent key-value store for flash storage
Authors: * The Facebook Database Engineering Team
* Build on earlier work on leveldb by Sanjay Ghemawat
(sanjay@google.com) and Jeff Dean (jeff@google.com)
This code is a library that forms the core building block for a fast
key value server, especially suited for storing data on flash drives.
It has an Log-Structured-Merge-Database (LSM) design with flexible tradeoffs
between Write-Amplification-Factor(WAF), Read-Amplification-Factor (RAF)
and Space-Amplification-Factor(SAF). It has multi-threaded compactions,
making it specially suitable for storing multiple terabytes of data in a
single database.
The core of this code has been derived from open-source leveldb.
The code under this directory implements a system for maintaining a
persistent key/value store.
See doc/index.html and github wiki (https://github.com/facebook/rocksdb/wiki)
for more explanation.
The public interface is in include/*. Callers should not include or
rely on the details of any other header files in this package. Those
internal APIs may be changed without warning.
Guide to header files:
include/rocksdb/db.h
Main interface to the DB: Start here
include/rocksdb/options.h
Control over the behavior of an entire database, and also
control over the behavior of individual reads and writes.
include/rocksdb/comparator.h
Abstraction for user-specified comparison function. If you want
just bytewise comparison of keys, you can use the default comparator,
but clients can write their own comparator implementations if they
want custom ordering (e.g. to handle different character
encodings, etc.)
include/rocksdb/iterator.h
Interface for iterating over data. You can get an iterator
from a DB object.
include/rocksdb/write_batch.h
Interface for atomically applying multiple updates to a database.
include/rocksdb/slice.h
A simple module for maintaining a pointer and a length into some
other byte array.
include/rocksdb/status.h
Status is returned from many of the public interfaces and is used
to report success and various kinds of errors.
include/rocksdb/env.h
Abstraction of the OS environment. A posix implementation of
this interface is in util/env_posix.cc
include/rocksdb/table_builder.h
Lower-level modules that most clients probably won't use directly
include/rocksdb/cache.h
An API for the block cache.
include/rocksdb/compaction_filter.h
An API for a application filter invoked on every compaction.
include/rocksdb/filter_policy.h
An API for configuring a bloom filter.
include/rocksdb/memtablerep.h
An API for implementing a memtable.
include/rocksdb/statistics.h
An API to retrieve various database statistics.
include/rocksdb/transaction_log.h
An API to retrieve transaction logs from a database.
Design discussions are conducted in https://www.facebook.com/groups/rocksdb.dev/