From ed123baa1bd00437f8db4a8849ee206c79963545 Mon Sep 17 00:00:00 2001 From: "Eric S. Raymond" Date: Mon, 29 Sep 1997 15:36:26 +0000 Subject: Added a won't-do-it note. svn path=/trunk/; revision=1433 --- design-notes.html | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) (limited to 'design-notes.html') diff --git a/design-notes.html b/design-notes.html index d0c8549e..1d3f478d 100644 --- a/design-notes.html +++ b/design-notes.html @@ -10,7 +10,7 @@
Back to Fetchmail Home Page To Site Map -$Date: 1997/08/05 04:14:49 $ +$Date: 1997/09/29 15:36:26 $

Design Notes On Fetchmail

@@ -171,7 +171,7 @@ necessary decoder out of the fetchmail code itself to get it.

All .fetchmailrc encryption would do is give a false sense of security to people who don't think very hard.

-

2. Truly concurrent queries to multiple hosts

+

Truly concurrent queries to multiple hosts

Occasionally I get a request for this on "efficiency" grounds. These people aren't thinking either. True concurrency would do nothing to lessen @@ -188,6 +188,25 @@ Fortunately, I've only seldom seen a server that incurred significant wait time on an individual response. I judge the gain from this not worth the hideous complexity increase it would require in the code.

+

Multiple concurrent instances of fetchmail

+ +What would be required for this is a per-host semaphore asserted +during each poll.

+ +The fundamental problem here is how an instance of fetchmail polling +host foo can assert that it's doing so in a way visible to all other +fetchmails. System V semaphores would be ideal for this purpose, but +they're not portable.

+ +I've thought about this a lot and roughed up several designs. All are +complicated and fragile, with a bunch of the standard problems (what +happens if a fetchmail aborts before clearing its semaphore, and how +do we recover reliably?)

. + +I'm not satisfied that there's enough functional gain here to pay +for the large increase in complexity that adding these semaphores +would entail.

+

Multidrop and alias handling

I decided to add the multidrop support partly because some users were @@ -383,7 +402,7 @@ all shaped the design in one way or another.

Back to Fetchmail Home Page To Site Map -$Date: 1997/08/05 04:14:49 $ +$Date: 1997/09/29 15:36:26 $

Eric S. Raymond <esr@snark.thyrsus.com>
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