ASP.Net and file changes on FreeBSD

[Ivan Radovanovic]

On 03/18/15 11:27, Ivan Radovanovic napisa:
> On 03/06/15 09:16, Ivan Radovanovic napisa:
>> Hi,
>>
>> I am running latest ASP.Net using latest mono from ports (3.10) on
>> FreeBSD 10.1 and it seems it is unable to detect changes on (some?)
>> files. What confuses me is that if I run xsp for testing project it is
>> unable to realize that project DLL is recompiled, or if I change
>> web.config it won't restart application manually, or if aspx file is
>> changed it won't recompile it, but if I add new aspx file then it will
>> try to compile that. It seems to me like it is able to detect file
>> addition but not change.
>>
>> Is there some workaround for this?
>>
>> Kind regards,
>> Ivan
>>
>> P.S.
>> Is there some dedicated website/forum for mono on FreeBSD - I saw some
>> page on mono project site but that is completely outdated and I also saw
>> BSD# page on google, but that also seems little bit old? I did little
>> bit of work on having up-to-date xsp/fast-cgi and monodevelop to
>> compile/work on freebsd so I would like to pass that to somebody from
>> freebsd-mono group so it could eventually reach ports :-)
>
> This is actually more interesting problem than what I expected, here are
> conclusions up to this point:
>
> * 3.10.0 has completely broken kevent implentation of FileSystemWatcher
> - so it couldn't restart application because it is not able to detect
> any file changes (I gave up on patching this implementation with latest
> code when I saw that 3.12.1 is ported to FreeBSD)
>
> * 3.12.1 has proper support for FileSystemWatcher, but I suspect
> something in System.Web.dll is broken (for example it properly detects
> dll change (writes message about that), but doesn't restart
> application), I am still unable to pinpoint exact problem there
>
> * 3.2.3 has partially working FileSystemWatcher (using kevent) - it is
> not able to catch file changes but only file creations/deletions, for
> that reason changes using editors like ee which really change file
> contents (not changing inode number) go undetected, but changes with
> editors which recreate file (like monodevelop or gedit for example) are
> properly captured and handled. This version also properly restarts
> application when dll is changed.
>
> I was using identical xsp for all mono versions to rule out differences
> there (I didn't do any tests using fastcgi server or mod_mono - will
> probably do that once I have xsp working as expected).

There were 2 problems here (applies to 3.12.1):

* FileSystemWatcher implementation for kevent was relying on Darwin's 
specific behavior (when kevent is executed with NULL timeout, if kqueue 
FD is closed kevent call on Darwin returns with error, however FreeBSD 
doesn't behave that way), so instead of using (almost) blocking version 
of kevent I put reasonable timeout there (instead of 500 seconds they 
had I put 0.5 seconds)

* HttpApplicationFactory wasn't able to restart application domain 
because of deadlock within FileSystemWatcher (basically file changed 
notification is executed from watcher's thread and then there is attempt 
to disable watcher from that same thread). I resolved this by creating 
separate thread to post events.

As far as I can tell at least xsp now works as expected (restaring 
application on DLL changes, recompiling changed files if .aspx file is 
changed), I will probably test at least fastcgi server soon as well, and 
I will try to find solution which would work with blocking kevent.

Attached is patch for latest mono version in ports (3.12.1) - patch file 
should be saved to files subdirectory of port and port should be rebuilt 
after that.