Bento is a new Bencoding library for Elixir focusing on incredibly fast speed without sacrificing simplicity, completeness, or correctness.
It takes inspiration from Poison, a pure-Elixir JSON library, and uses several techniques found there to achieve this speed:
- Extensive sub-binary matching
- A hand-rolled parser using several techniques known to benefit HiPE for native compilation
- IO list encoding
- Single-pass decoding
Additionally, and unlike some other Elixir bencoding libraries, Bento will also reject all malformed input. This guarantees you're working with a well-formed bencoded file.
Preliminary benchmarking shows that Bento performs over 2x faster when encoding, and at least as fast when decoding, compared to other existing Elixir libraries.
Bento is available in Hex. The package can be installed by:
-
Add bento to your list of dependencies in
mix.exs:{:bento, "~> 0.9"} -
Update your dependencies.
$ mix deps.get
Encoding an Elixir data type:
iex> Bento.encode([1, "two", [3]])
{:ok, "li1e3:twoli3eee"}
iex> Bento.encode!(%{"foo" => ["bar", "baz"], "qux" => "norf"})
"d3:fool3:bar3:baze3:qux4:norfe"Decoding a bencoded string:
iex> Bento.decode("li1e3:twoli3eee")
{:ok, [1, "two", [3]]}
iex> Bento.decode!("d3:fool3:bar3:baze3:qux4:norfe")
%{"foo" => ["bar", "baz"], "qux" => "norf"}Bento is also metainfo-aware and comes with a .torrent decoder out of the box:
iex> File.read!("test/_data/ubuntu-14.04.4-desktop-amd64.iso.torrent") |> Bento.torrent!()
%Bento.Metainfo.Torrent{announce: "http://torrent.ubuntu.com:6969/announce",
"announce-list": [["http://torrent.ubuntu.com:6969/announce"],
["http://ipv6.torrent.ubuntu.com:6969/announce"]],
comment: "Ubuntu CD releases.ubuntu.com", "created by": nil,
"creation date": 1455826371, encoding: nil,
info: %Bento.Metainfo.SingleFile{length: 1069547520, md5sum: nil,
name: "ubuntu-14.04.4-desktop-amd64.iso", "piece length": 524288,
pieces: <<109, 235, 143, 234, 36, 25, 142, 36, 20, 3, 227, 227, 134, 136, 205, 130, 176, ...>>,
private: nil}}Since Bento uses Poison's Decoder module for .torrent(), this means it also supports decoding bencoded data into any struct you choose, like so:
defmodule Name do
defstruct [:family, :given]
end
iex> Bento.decode!("d6:family4:Folz5:given6:Rodneye", as: %Name{})
%Name{family: "Folz", given: "Rodney"}$ MIX_ENV=bench mix bench
We currently benchmark against: Bento (this project), bencode, Bencodex, and bencoder.
We are aware of, but unable to benchmark against: exbencode (build errors), and elixir_bencode (module name conflicts with Bencode).
PRs that add libraries to the benchmarks are greatly appreciated!
See LICENSE.