[Kde-pim] Re: Moving Trojitá to extragear

[Jan Kundrát]

On Tuesday, 27 November 2012 22:52:24 CEST, Christian Mollekopf wrote:
> Sure, on the other hand the session does exactly that (as you 
> noted below) and is well separated from the parsing.

I disagree on the topic of separation -- if you take a look at fetchjob.cpp in particular, you'll see that the quote an amount of the actual parsing happens at the level of job, not earlier in the process.

> I'm just wondering why you think it 
> wouldn't be possible to implement pipelining (relatively easily) in that 
> session, as that might be something I'd want to do eventually (as you 
> mentioned you got substantial performance improvements). So I'm 
> just trying to 
> learn from your experience here.
>
> AFAIK pipelining is the following:
> - You send a bunch of commands (which support pipelining), 
> without waiting for 
> a response
> - You match the response to the sent command using the tag at 
> the beginning of 
> each command.

In IMAP, each command results in a response tagged with the same tag as you used in the command. So far, so good. However, plenty of command result in untagged responses as well, and as a bonus, servers are explicitly allowed to send untagged responses even without any command being in progress, completely on their own.

One possible solution to this is to work as Trojita does, i.e. start offering each received response to each active job, stopping as soon as a job declares the response as "handled". I cannot guess how much work that might involve.

In Trojita, we also have some auxiliary "jobs" (KeepMailboxOpenTask) which process any incoming responses containing mailbox updates. In fact, our equivalent of fetchjob.cpp does not handle FETCH responses at all -- the untagged FETCH responses are processed by the KeepMailboxOpenTask.cpp. This way, we don't care whether something like, say, a FETCH FLAGS is triggered by something on the server's side or as a result of an explicit FETCH command.

Hope this helps,
Jan
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