nnrss: handle unavailability of rss server more gracefully?

nnrss: handle unavailability of rss server more gracefully?

[Michael Schierl]

Hi,

today my emacs crashed (i.e. hanged) when fetching news. A few
edebug sessions later, i knew that the problem was in

mm-url-insert, which was called by an unreachable (timing out) host
name. wget (mm-url-program is `wget' here) seems to try to fetch the
file indefinitely (at least several minutes). So I thought the proper
way would be to do

(setq mm-url-predefined-programs 
'((wget "wget" "-T" "10" "-t" "1" "--user-agent=mm-url" "-q" "-O"
"-")))

to make wget fail after 10 seconds. However, this will signal an error
and this error prevents updating the rest of the groups.

As a workaround, I put nnrss: to Denied in the server buffer (this
allows me at least to fetch news from nntp server, but not the other
rss feeds).

Can I deny only one single RSS feed? And would it be possible for
nnrss to notice when a feed is down and fetch the others nevertheless?

Michael

Re: nnrss: handle unavailability of rss server more gracefully?

[Lars Magne Ingebrigtsen]

Michael Schierl <schierlm-usenet@gmx.de> writes:

> mm-url-insert, which was called by an unreachable (timing out) host
> name. wget (mm-url-program is `wget' here) seems to try to fetch the
> file indefinitely (at least several minutes). So I thought the proper
> way would be to do
>
> (setq mm-url-predefined-programs 
> '((wget "wget" "-T" "10" "-t" "1" "--user-agent=mm-url" "-q" "-O"
> "-")))
>
> to make wget fail after 10 seconds. However, this will signal an error
> and this error prevents updating the rest of the groups.

nnrss shouldn't bug out in these situations.  Could you `(setq
debug-on-error t)', repeat the bug and mail me the resulting
backtrace.

-- 
(domestic pets only, the antidote for overdose, milk.)
  larsi@gnus.org * Lars Magne Ingebrigtsen

Re: nnrss: handle unavailability of rss server more gracefully?

[Michael Schierl]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> Michael Schierl <schierlm-usenet@gmx.de> writes:

>> to make wget fail after 10 seconds. However, this will signal an error
>> and this error prevents updating the rest of the groups.
>
> nnrss shouldn't bug out in these situations.  Could you `(setq
> debug-on-error t)', repeat the bug and mail me the resulting
> backtrace.

Since no server is down now, I aliased one of my RSS feed's host to
localhost ;)

Debugger entered--Lisp error: (error "Couldn't fetch http://********.****.com/rss.aspx")
  signal(error ("Couldn't fetch http://********.****.com/rss.aspx"))
  error("Couldn't fetch %s" "http://********.****.com/rss.aspx")
  mm-url-insert-file-contents-external("http://********.****.com/rss.aspx")
  mm-url-insert-file-contents("http://********.****.com/rss.aspx")
  byte-code("[some garbage...]" [mm-url-timeout with-timeout-tag with-timeout-timer first mm-url-retries times run-with-timer nil with-timeout-handler message "Trying again (%s)..." mm-url-insert-file-contents re-search-forward "<meta[ 	^M\n]*http-equiv=\"Refresh\"[^>]*URL=\\([^\"]+\\)\"" t match-string 1 mm-url-insert follow-refresh url result done with-timeout-value] 5)
  mm-url-insert("http://********.****.com/rss.aspx")
  nnrss-fetch("http://********.****.com/rss.aspx")
  nnrss-check-group("******* Forums" "")
  nnrss-request-group("******* Forums" "" nil)
  gnus-activate-group("nnrss:******* Forums" scan)
  gnus-get-unread-articles(nil)
  gnus-group-get-new-news(nil)
* call-interactively(gnus-group-get-new-news)

HTH,

Michael

Re: nnrss: handle unavailability of rss server more gracefully?

[Lars Magne Ingebrigtsen]

Michael Schierl <schierlm-usenet@gmx.de> writes:

> Since no server is down now, I aliased one of my RSS feed's host to
> localhost ;)

[...]

>   nnrss-request-group("******* Forums" "" nil)
>   gnus-activate-group("nnrss:******* Forums" scan)
>   gnus-get-unread-articles(nil)

But the thing is that the call to `nnrss-request-group' is wrapped in
a `condition-case', so you shouldn't see anything (except warning
message) if you have debug-on-quit/error switched off.  Do you?

-- 
(domestic pets only, the antidote for overdose, milk.)
  larsi@gnus.org * Lars Magne Ingebrigtsen

Re: nnrss: handle unavailability of rss server more gracefully?

[Michael Schierl]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> Michael Schierl <schierlm-usenet@gmx.de> writes:
>
>> Since no server is down now, I aliased one of my RSS feed's host to
>> localhost ;)
>
> [...]
>
>>   nnrss-request-group("******* Forums" "" nil)
>>   gnus-activate-group("nnrss:******* Forums" scan)
>>   gnus-get-unread-articles(nil)
>
> But the thing is that the call to `nnrss-request-group' is wrapped in
> a `condition-case', so you shouldn't see anything (except warning
> message) if you have debug-on-quit/error switched off.  Do you?

I see an error message and hear a beep - and my fetchnews script is
not continued but aborted¹ - so either there is no condition-case in
the version I am using here, or my Emacs is borken...

(btw - a debug-on-error should not start the debugger on an error
inside condition-case, should it?)

Michael

¹ My Emacs is still showing "--- Fetching news ---" in the title bar now

Re: nnrss: handle unavailability of rss server more gracefully?

[Lars Magne Ingebrigtsen]

Michael Schierl <schierlm-usenet@gmx.de> writes:

> I see an error message and hear a beep - and my fetchnews script is
> not continued but aborted¹ - so either there is no condition-case in
> the version I am using here, or my Emacs is borken...

And this is with debug-on-* off?

> (btw - a debug-on-error should not start the debugger on an error
> inside condition-case, should it?)

No, normally it doesn't, but the Gnus code switched the
condition-case off when you have those variables on to make it
possible to debug stuff that really goes wrong.

-- 
(domestic pets only, the antidote for overdose, milk.)
  larsi@gnus.org * Lars Magne Ingebrigtsen

Re: nnrss: handle unavailability of rss server more gracefully?

[Michael Schierl]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> Michael Schierl <schierlm-usenet@gmx.de> writes:
>
>> I see an error message and hear a beep - and my fetchnews script is
>> not continued but aborted¹ - so either there is no condition-case in
>> the version I am using here, or my Emacs is borken...
>
> And this is with debug-on-* off?

Think so.

,----[ C-h v debug-on-error RET ]
| debug-on-error's value is nil
| 
| [...]
`----

,----[ C-h v debug-on-quit RET ]
| debug-on-quit's value is nil
| 
| [...]
`----

>> (btw - a debug-on-error should not start the debugger on an error
>> inside condition-case, should it?)
>
> No, normally it doesn't, but the Gnus code switched the
> condition-case off when you have those variables on to make it
> possible to debug stuff that really goes wrong.

Hmm, neat...

Michael

Re: nnrss: handle unavailability of rss server more gracefully?

[Lars Magne Ingebrigtsen]

Michael Schierl <schierlm-usenet@gmx.de> writes:

>> And this is with debug-on-* off?
>
> Think so.

Do you have an nnrss group that doesn't work that I can test with?
Perhaps the output from `G E' on the group would be helpful...

-- 
(domestic pets only, the antidote for overdose, milk.)
  larsi@gnus.org * Lars Magne Ingebrigtsen

Re: nnrss: handle unavailability of rss server more gracefully?

[Michael Schierl]

Lars Magne Ingebrigtsen <larsi@gnus.org> writes:

> Michael Schierl <schierlm-usenet@gmx.de> writes:
>
>>> And this is with debug-on-* off?
>>
>> Think so.
>
> Do you have an nnrss group that doesn't work that I can test with?

For my tests i used http://channel9.msdn.com/rss.aspx

However, most of the time this is up, so i aliased channel9.msdn.com
to 127.0.0.1 in my hosts file (I don't have a web server running) to
reproduce the bug. (so that Gnus will get a "Connection Refused").

> Perhaps the output from `G E' on the group would be helpful...

("nnrss:Channel9 Forums" 3
 ((1 . 39))
 ((seen
   (1 . 97)))
 (nnrss ""))

Michael

Re: nnrss: handle unavailability of rss server more gracefully?

[Ken Coleman]

Michael Schierl <schierlm-usenet@gmx.de> writes:

> Lars Magne Ingebrigtsen <larsi@gnus.org> writes:
>
>> Michael Schierl <schierlm-usenet@gmx.de> writes:
>>
>>>> And this is with debug-on-* off?
>>>
>>> Think so.
>>
>> Do you have an nnrss group that doesn't work that I can test with?
>
> For my tests i used http://channel9.msdn.com/rss.aspx
>
> However, most of the time this is up, so i aliased channel9.msdn.com
> to 127.0.0.1 in my hosts file (I don't have a web server running) to
> reproduce the bug. (so that Gnus will get a "Connection Refused").
>
>> Perhaps the output from `G E' on the group would be helpful...
>
> ("nnrss:Channel9 Forums" 3
>  ((1 . 39))
>  ((seen
>    (1 . 97)))
>  (nnrss ""))
>
> Michael

What was the resolution to this thread?  I am having all of the exact
same symptoms, except my RSS feed it
http://www.insidemacgames.com/news/rss.php

Same debug-on-* settings (all nil), same use of an external fetcher
for the feed, etc.

Thanks in advance for any assistance!
- Ken.
ken_coleman@iname.com