11

When I try to load a feed using Miranda RSSNews plugin, it only loads on startup.

The root of the problem seems to be in the server-side cache which does not seem to grace If-Modified-Since when using Accept-Encoding: gzip:

GET /feeds/tag?tagnames=oracle+or+sql+or+rdbms+or+dbms+or+database+or+mysql+or+postgresql+or+tsql+or+sql-server HTTP/1.0
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) RSSNews plugin for Miranda IM
If-Modified-Since: Mon, 11 Apr 2011 15:09:39 GMT
A-IM: feed
Accept-Encoding: gzip, deflate
Host: stackoverflow.com
Connection: Keep-Alive
Proxy-Connection: Keep-Alive

HTTP/1.1 304 Not Modified
Cache-Control: public, max-age=0
Expires: Mon, 11 Apr 2011 15:14:39 GMT
Last-Modified: Mon, 11 Apr 2011 15:09:39 GMT
Vary: *
Date: Mon, 11 Apr 2011 17:04:37 GMT
Connection: keep-alive

Compare to:

GET /feeds/tag?tagnames=oracle+or+sql+or+rdbms+or+dbms+or+database+or+mysql+or+postgresql+or+tsql+or+sql-server HTTP/1.1
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) RSSNews plugin for Miranda IM
If-Modified-Since: Mon, 11 Apr 2011 15:09:39 GMT
A-IM: feed
Host: stackoverflow.com
Connection: Keep-Alive
Proxy-Connection: Keep-Alive

HTTP/1.1 200 OK
Cache-Control: public, max-age=0
Content-Type: application/atom+xml; charset=utf-8
Expires: Mon, 11 Apr 2011 17:20:18 GMT
Last-Modified: Mon, 11 Apr 2011 17:15:18 GMT
Vary: *
Date: Mon, 11 Apr 2011 17:23:16 GMT
Content-Length: 72163

Update:

Seems that the feeds don't expire for too long even without the gzip encoding. Just run this:

GET /feeds/tag?tagnames=oracle+or+sql+or+rdbms+or+dbms+or+database+or+mysql+or+postgresql+or+tsql+or+sql-server&sort=newest HTTP/1.0
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) RSSNews plugin for Miranda IM
A-IM: feed
Host: stackoverflow.com
Connection: Keep-Alive
Proxy-Connection: Keep-Alive

HTTP/1.1 200 OK
Cache-Control: public, max-age=0
Content-Type: application/atom+xml; charset=utf-8
Expires: Wed, 13 Apr 2011 15:24:30 GMT
Last-Modified: Wed, 13 Apr 2011 15:19:30 GMT
Vary: *
Date: Wed, 13 Apr 2011 21:28:42 GMT
Content-Length: 78697
Connection: keep-alive

It returns the feed as of Wed, 13 Apr 2011 15:19:30 GMT despite the fact it was requested 6 hours later and the expiration time was only 5 minutes.

4

We had a bug in our output-cache provider, so it used sliding instead of absolute expiry. So it was only when the readers stopped hitting it that it would expire.

Fixed next deploy.

  • Trusting you on this one! – Quassnoi Jul 1 '11 at 14:33
2

The issue seems to be fixed by now.

  • You sure about that? – Ufuk Hacıoğulları Apr 18 '11 at 7:40
  • @Narsil: my reader has no more than 5 minutes delay now. – Quassnoi Apr 18 '11 at 9:31
  • Interesting; I couldn't see any obvious cause here (or, indeed, repro); I've just come back to re-investigate, so I'm intrigued that it has gone away. I wonder if this was a dodgy intermediary caching something incorrectly? – Marc Gravell Apr 18 '11 at 11:39
  • @Marc: probably. Actually, I tried this from two separate IP addresses and it seemed that two different versions of the cache were returned (though on they day I asked they both did not expire on time). Now, the feeds seem to expire properly from both IP addesses (and I switched to StackGuru anyway as suggested by Jeff here: meta.stackexchange.com/questions/87575/…). – Quassnoi Apr 18 '11 at 11:44
  • Actually, it wasn't fixed. But it will be next deploy. – Marc Gravell Jul 1 '11 at 11:54

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