[haiku-development] Re: AddOnMonitorHandler

  • From: "Stephan Assmus" <superstippi@xxxxxx>
  • To: haiku-development@xxxxxxxxxxxxx
  • Date: Fri, 27 Aug 2010 08:52:24 +0200


> is there a special reason why AddOnMonitorHandler *) needs a B_PULSE  
> message runner to trigger the add-on handling of the pending entries? Why 
> not just post a B_PULSE into the message queue from within the handler  
> when a new entry is created?
> Is it really necessary to have a pending entry list? and thus a B_PULSE  
> message? Why not handle the entries in the same cycle? Ok it makes it a  
> little bit more multi threaded when scanning the directory the first time 
> but I see no advantage in this case.

It is probably good to handle notifications in the expected thread, and 
asynchronously to the AddDirectory() call. The mechanism with the pulse 
messages could be improved. I take it it is supposed to let things settle down 
a bit. For example a file might quickly appear and disappear and it will be 
ignored. Also many notifications could arrive and should cause only one action. 
As you say the pulse message could be send when receiving the first event, that 
would certainly remove the running of the thread when nothing goes on. Just to 
give an example of why batching notifications can be good: In the time it takes 
the linker to produce a new ffmpeg plugin binary, there arrive enough stat 
changed notifications that the media_server manages to unload the user ffmpeg 
version, unshadow the system ffmpeg version and reshadow it with the user 
version about seven to ten times in a row. :-) I put the TODO into the 
AddOnMonitorHandler before testing this, but I am surprised it would be as

Best regards,

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