Re: [GENERAL] Reduce the time to know trigger_fi​le's existence - Mailing list pgsql-general

From Harshitha S
Subject Re: [GENERAL] Reduce the time to know trigger_fi​le's existence
Date
Msg-id CAAe0G5tLJCCjfMLTPS9gfzQiW+EyVZewxg8k01OS6tnyqs_KxQ@mail.gmail.com
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In response to Re: Reduce the time to know trigger_fi​le's existence  (Craig Ringer <ringerc@ringerc.id.au>)
Responses Re: Reduce the time to know trigger_fi​le's existence
List pgsql-general
Hi,

Can Latch - that postgres already uses, be used to achieve the same?

On Tue, Sep 4, 2012 at 6:31 AM, Craig Ringer <ringerc@ringerc.id.au> wrote:
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

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