Re: GSoC 2011 project proposal [Add kqueue support to GIO]

[Mindaugas Rasiukevicius <rmind%netbsd.org@localhost>]

Dmitry Matveev <me%dmitrymatveev.co.uk@localhost> wrote:
> > Would be nice to provide a detailed description of what kqueue lacks
> > during the early stages of the project.  It might be the case that
> > it's impossible to extend kqueue to implement some important
> > functionality... in which case we could be looking at a different
> > project altogether (e.g. implement inotify in the kernel)!
> 
>  I have found that kqueue does not have analogues to the following
>  inotify events:
> 
>  1. IN_ACCESS        - File was read from
>  2. IN_OPEN          - File was opened
>  3. IN_CLOSE_WRITE   - File was closed (and was open for writing)
>  4. IN_CLOSE_NOWRITE - File was closed (and was not open for writing)
>  5. IN_MOVED_FROM    - File was moved away from a watched directory
>  6. IN_MOVED_TO      - File was moved into a watched directory
> 
>  There is also the IN_UNMOUNT event. According to manual, kqueue has
>  the NOTE_REVOKE event to signal that the underlying fileystem was
>  unmounted, but I could not reach this behaviour. The fact that
>  kqueue requires an open file descriptor per entry complicates the
>  monitoring on removable devices.
> 
>  Inotify also provides an additional information for several
>  notifications, i.e. for MOVED_FROM/MOVED_TO events it also supplies
>  a name of the file moved. Technically for kqueue this information
>  can be passed from kernel via kevent.data (if to consider this field
>  as a pointer).
> 
>  Determining the possibility of extending kqueue with this additional
>  functionality requires a deeper analysis, I have planned it on the
>  community bonding period.

Solaris has Event Port interface, an equivalent of inotify, which has
mentioned capabilities.  I would suggest to evaluate its interface:

http://blogs.sun.com/praks/entry/file_events_notification
(see man pages as well)

Having it in the kernel - might be something to consider.  Also, AFAIK,
GIO already has support for it.

-- 
Mindaugas