Re: Reduce the time to know trigger_fi​le's existence

On 09/03/2012 04:30 PM, Harshitha S wrote:
> Hi,
> We are trying to introduce a thread that monitors the creation of the
> trigger_file. As and when the file is created, the process that monitors
> postgres server needs to be notified through the inotify API.

File system notification APIs aren't portable. If you want to implement
this you'll need to support at least the Windows FSNotify stuff,
notification features compatible with several different Linux versions
and with the BSDs, with a fallback to polling for other platforms.

For Windows:

http://msdn.microsoft.com/en-us/library/windows/desktop/aa365261(v=vs.85).aspx

For Linux it appears that inotify has been present since 2005:

http://en.wikipedia.org/wiki/Inotify

but it's probably best to add a configure test and fall back to polling
if it isn't found.

This will mean adding a new internal API and then adding backend/port/
implementations for various platforms, as well as taking the current
code and splitting it out into a port file that gets used if no other is
chosen.

This page is likely to be useful:

http://wiki.postgresql.org/wiki/So,_you_want_to_be_a_developer%3F

--
Craig Ringer