Gitarella born as a replacement for gitweb, as it wasn't providing something I
was looking for: direct URLs pointing to files in the repository.

The decision to make it a Ruby webapp was due to my passion for Ruby and the
availability of a lot of tools to write Web Applications, like CGI and FastCGI
libraries, and HTML template libraries and so on.

The current code, while not as evolved as gitweb's, can do basic browsing of the
repositories' tree and handle diff view of the changesets.

To be able to run gitarella you need:

- a webserver able to handle CGI or FastCGI requests (tested and developed using
lighttpd, but Apache should work just as fine);
- Ruby version 1.8;
- for FastCGI support, ruby-fcgi extension
  ( http://raa.ruby-lang.org/list.rhtml?name=fcgi );
- for memcached backend, Ruby-MemCache extension
  ( http://www.deveiate.org/projects/RMemCache/ );
- diff-lcs extensions, mandatory for diff viewing
  ( http://raa.ruby-lang.org/project/diff-lcs ); TODO, make this optional;
- htmlentities extension, mandatory ( http://htmlentities.rubyforge.org/ );
- filemagic extension, required for serving proper mime-types of the files, both
  statics and raw from the repository; optional but highly suggested
  ( http://grub.ath.cx/filemagic/ );
- and of course GIT (developed using version 1.4.0).

Compared to gitweb, Gitarella tries to focus more on limiting the disk I/O when
reading almost-static data. This is achieved through the optional memcached
support, that will keep cached in memory all the data read for repositories,
commits and tags.

This can be done safely by using the SHA1 of the objects to memorize them in
the cache: as the objects are immutables, the cache can be maintained
indefinitely. This reduces a lot the time required for reading the data through
the git commands and for parsing it into a Ruby-usable object.