Pop optimisation

[Servant Cyril]

Hello,

Here is a patch for optimizing pop. Let me explain : Here we have lots (millions) of mailboxes. Many people connect to pop every few minutes, doing LIST, and if there are mails, they do RETR and DELE. Most of time, there is no mail (for 138770 pop connections, there was no mail 92498 times => 66.6%). Without the patch, the seen, index, cache and header files are opened. With this patch, we only read statuscache.db (which is already opened) when there is no mail.

On the stat image joined, you can see what's happening when we empty statuscache.db (at 10:51) : pop optimization doesn't work the first time a client connects to pop (Lots of reads), and then, as the same clients connect again to pop, reads slowly decrease. Without the patch, reads would stay high.

--
Cyril Servant


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