Modifies ::BSON::ByteBuffer#get_int64 to return Fixnum not Bignum

bson_bignum_patch.rb

# ByteBuf#getInt64 should return Fixnum not Bignum
# Issue: https://jira.mongodb.org/browse/RUBY-1189
# Example: http://pastie.org/10978801#1,14,17,19,25
# Gist: https://gist.github.com/kml/4c76c22df26a1fa372c97aff93e873ab

require "bson"

unless BSON::ByteBuffer.new(2200000227.to_bson.to_s).get_int64.is_a?(Bignum)
  abort "#{__FILE__}: BSON::ByteBuffer#get_int64 already fixed! Remove this patch."
end

::BSON::ByteBuffer.class_eval do
  alias :get_int64_bignum :get_int64

  def get_int64
    org.jruby.RubyBignum.big2long(get_int64_bignum)
  end
end