My snappy wrapper from earlier in the week to show igrigorik

extconf.rb

require 'mkmf'

# Give it a name
extension_name = 'lrsnappy'

# The destination
dir_config(extension_name)

$LIBS << " -lstdc++ -lsnappy"

# Do the work
create_makefile(extension_name)

rsnappy.cc

 #include <ruby.h>
 #include <snappy.h>
 
    using namespace snappy;

    typedef VALUE (ruby_method)(...);


    extern "C" VALUE compress(VALUE self, VALUE input, VALUE length) {
      string *out = new string();
      char *in = StringValuePtr(input);
      size_t sz = snappy::Compress(in, NUM2INT(length), out);
      VALUE ret = rb_str_new(out->c_str(), sz);
      delete out;
      return ret;
    }

    extern "C" VALUE uncompress(VALUE self, VALUE input, VALUE length) {
      VALUE ret;
      string *out = new string();
      char* str = StringValuePtr(input);
      bool pass = snappy::Uncompress(str, NUM2INT(length), out);

      if (pass)
        ret = rb_str_new(out->c_str(), out->length());
      else
        ret = Qnil;

      delete out;
      return ret;
    }

    extern "C" VALUE init(VALUE self)
    {
       return self;
    }


    static VALUE RSnappy;

    extern "C" void Init_lrsnappy() 
    {
        RSnappy = rb_define_class("LRSnappy", rb_cObject);
        rb_define_method(RSnappy, "initialize", (ruby_method*) &init, /*n_args*/0);
        rb_define_method(RSnappy, "_compress", (ruby_method*) &compress, 2);
        rb_define_method(RSnappy, "_uncompress", (ruby_method*) &uncompress, 2);
    }

rsnappy.rb

require 'lrsnappy'

class RSnappy
  def self.compress(value)
    LRSnappy.new._compress(value, value.length)
  end

  def self.uncompress(value)
    LRSnappy.new._uncompress(value, value.length)
  end
end