which log parser gem/lib shall i use in ruby?

Now i want choose a ruby log parser gem to parse my own log files, after investigation i found there are rawk, log analyzer and so on. My requirements 开发者_StackOverflow中文版are:

1. log file format is defined by ourselves, it can parse our log file.
2. log file is large such as 1G or so.
3. require to parse at real time.
4. forward the parse result into database, we can do it by ourselves.

if you are familar with ruby log parser, could u recommend one to me according to our requirements? thank you in advance.