Description

The esnappy library provides Erlang bindings to Google's Snappy compression library. It uses separate OS thread for compression/decompression so it won't screw up Erlang's VM scheduler while processing large data chunks.

Erlang Version

The esnappy library requires Erlang R14B or later.

Building

You have to have Snappy library installed on your system so that compiler can link against it. You can also specify ESNAPPY_INCLUDE_DIR and ESNAPPY_LIB_DIR enviroment variables for better control of paths used to compile and link esnappy library.

$ ESNAPPY_INCLUDE_DIR=/usr/local/include ESNAPPY_LIB_DIR=/usr/local/lib ./rebar compile
$ ./rebar eunit

Perfomance

Erlang R14B02 (erts-5.8.3) [source] [64-bit] [smp:4:4] [rq:4] [async-threads:0] [hipe] [kernel-poll:false]

Eshell V5.8.3  (abort with ^G)
1> code:add_path("ebin").
true
2> {ok, Data} = file:read_file("test/text.txt").
{ok,<<32,32,32,208,155,208,181,208,178,32,208,157,208,
      184,208,186,208,190,208,187,208,176,208,181,208,
      178,208,...>>}
3> {ok, Ctx} = esnappy:create_ctx().
{ok,<<>>}
4> {ST, {ok, SCompressed}} = timer:tc(esnappy, compress, [Ctx, Data]).
{46692,
 {ok,<<217,192,187,1,84,32,32,32,208,155,208,181,208,178,
       32,208,157,208,184,208,186,208,190,208,187,...>>}}
5> {ZT, ZCompressed} = timer:tc(zlib, zip, [Data]).
{493585,
 <<172,189,203,110,37,219,145,37,56,207,175,56,17,147,146,
   10,78,126,64,196,128,227,4,106,212,104,52,...>>}
6> size(Data).
3072089
7> size(SCompressed).
1548017
8> size(ZCompressed).
832898

Note the difference in execution time 46692 (Snappy) vs. 493585 (zlib).