Implementation

These are initial, rough considerations for the implementation.

Thunar data will be presented by implementing the GtkTreeModel. On-top of this, there will be the ExoIconView and the GtkTreeView (as list view). The optional tree view pane needs a tree model backend as well, and we need a unified design for the backend code.

Initial implementation ideas for certain aspects of the file manager. Some of them contain sample code already.

• MIME Glob Match
• MIME Info Parser

Its very important to reduce disk seeks (notably stat()s and file content accesses). For the MIME detection, the file manager should probably even skip the magic-detection and use only the glob-detection (problem here, is that we need to grab the first 256 bytes anyways to detect if the file in question is a text file, as the fallback).

When writing code, try to avoid bugs as much as possible. This includes, always compiling with warnings enabled (-Wall) and let the compiler treat warnings as errors (-Werror). Make heavy use of the

Message Output and Debugging Functions provided by GLib. There are some other points that can help to avoid bugs from day one (already proven to work in other projects like xfce4-session - no critical implementation bugs during the 4.2 release phase! - and Terminal), and I’ll write down some notes about this at a later time. Others may also have some interesting tips, if so, feel free to send them to the thunar-dev mailinglist.

Fortunately, the Shared MIME Database Specification is well-thought, so there’s enough room for optimization on the implementors side. The most important point is to optimize the common case - the glob-detection - as much as possible. The most common case of a glob is *.EXT, an extension with 3 ASCII characters. Here the comparison can be speed up using a 32bit integer for the comparison instead of performing a comparison by character.

The filer repository contains samples of other optimizations.

ExoIconView can be optimized to avoid the time-consuming relayout calls. This requires changing most of the internals (sample code exists).

Thunar should preload all mimetype icons and create a hash-table with mimetype → icon for easy lookup when loading a directory. This will add some memory overhead, but might add some speed.

A sample implementation of the many of the above requirements exists in the CVS repository, the module name is filer. It should be noted, that this is really just sample code, which should be considered of prototype quality, but not production quality.

Some sample implementations are available online:

• MIME icon loading
• Thumbnail Loader/Generator