From: "Frank Ch. Eigler" <fche@redhat.com>
To: Mark Wielaard <mark@klomp.org>
Cc: elfutils-devel@sourceware.org, amerey@redhat.com
Subject: Re: patch 1/2 debuginfod client
Date: Mon, 18 Nov 2019 20:33:00 -0000 [thread overview]
Message-ID: <20191118203324.GD2880@redhat.com> (raw)
In-Reply-To: <356e88e4937ddb97a3e7cc93dbdfe29239ff960e.camel@klomp.org>
Hi -
> > > But since the user won't see the URL generated they might not notice
> > > what is really going on. They will just see that something wasn't
> > > found, won't they?
> >
> > Yes, so the only benefit would be the generation of a different error
> > message for impossible buildids.
>
> But if there are multiple server URLs it might not be clear which/where
> the error came from.
(My comment was about detecting even number of chars in the hex code.)
> Since all this is done through a very simple web
> api I think it is useful for the user to get informed about what the
> actual request URL was that failed. [...]
> If we go with the client connection context idea for the API we could
> add an extra function that would tell you the last URL tried maybe?
Yeah, maybe. They are tried in parallel. We could also hook up to
libcurl's own progress-notification callbacks.
> > > Do you know how other libraries that use libcurl deal with this?
> >
> > I looked over some other libcurl users in fedora. Some don't worry
> > about the issue at all, relying on implicit initialization, which is
> > only safe if single-threaded. Others (libvirtd) do an explicitly
> > invoked initialization function, which is also only safe if invoked
> > from a single-threaded context.
> >
> > I think actually our way here, running the init function from the
> > shared library constructor, is about the best possible. As long as
> > the ld.so process is done as normal, it should be fine. Programs that
> > use the elfutils trick of manual dlopen'ing libdebuginfod.so should do
> > so only if they are single-threaded.
>
> But they cannot really control that... Since they might not know (and
> really shouldn't care) that libdw lazily tries to dlopen
> libdebuginfod.so which then pulls in libcurl and calls that global init
> function...
>
> Could we do try to do the dlopen and global curl initialization from
> libdw _init, or a ctor, to make sure it is done as early as possible?
Doing a redundant initialization later is not a problem; there is a
counter in there. The problematic case would be
- a multithreaded application
- loading debuginfod.so multiply concurrently somehow
- and calling the solib ctor concurrently somehow
- and all of this concurrently enough to defeat libcurl's init-counter
IMHO, not worth worrying about. Someday libcurl will do the right
thing (tm) and plop this initialization into their solib ctor.
> > > I was more thinking zero == infinity (no timeout).
> >
> > An unset environment variable should do that.
>
> Are you sure? If DEBUGINFOD_TIMEOUT isn't set, then it seems it
> defaults to 5 seconds:
>
> /* Timeout for debuginfods, in seconds.
> This env var must be set for debuginfod-client to run. */
> static const char *server_timeout_envvar = DEBUGINFOD_TIMEOUT_ENV_VAR;
> static int server_timeout = 5;
> [...]
>
> if (getenv(server_timeout_envvar))
> server_timeout = atoi (getenv(server_timeout_envvar));
OK, hm, we could make an -empty- but set environment variable mean
'infinity'. Then again, a user can also say =99999.
- FChE
next prev parent reply other threads:[~2019-11-18 20:33 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-28 19:04 patch 0/2 debuginfod submission Frank Ch. Eigler
2019-10-28 19:06 ` patch 1/2 debuginfod client Frank Ch. Eigler
2019-10-28 19:09 ` patch 2/2 debuginfod server etc Frank Ch. Eigler
2019-11-04 21:48 ` patch 3/3 debuginfod client interruptability Frank Ch. Eigler
2019-11-07 9:07 ` patch 4 debuginfod: symlink following mode Frank Ch. Eigler
2019-11-07 9:08 ` patch 5 debuginfod: prometheus metrics Frank Ch. Eigler
2019-11-15 17:26 ` Mark Wielaard
2019-11-15 17:58 ` Frank Ch. Eigler
2019-11-18 16:20 ` Mark Wielaard
2019-11-18 16:48 ` Frank Ch. Eigler
2019-11-19 16:13 ` Mark Wielaard
2019-11-15 16:49 ` patch 4 debuginfod: symlink following mode Mark Wielaard
2019-11-15 18:31 ` Frank Ch. Eigler
2019-11-18 16:27 ` Mark Wielaard
2019-11-15 16:16 ` patch 3/3 debuginfod client interruptability Mark Wielaard
2019-11-15 17:03 ` Aaron Merey
2019-11-15 17:35 ` Mark Wielaard
2019-11-15 18:14 ` Pedro Alves
2019-11-17 23:44 ` Mark Wielaard
2019-11-18 2:50 ` Frank Ch. Eigler
2019-11-18 9:24 ` Pedro Alves
2019-11-19 12:58 ` Mark Wielaard
2019-11-13 17:22 ` patch 2/2 debuginfod server etc Mark Wielaard
2019-11-14 11:54 ` Frank Ch. Eigler
2019-11-16 1:31 ` Mark Wielaard
2019-11-13 23:19 ` Mark Wielaard
2019-11-14 12:30 ` Frank Ch. Eigler
2019-11-18 14:17 ` Mark Wielaard
2019-11-18 18:41 ` Frank Ch. Eigler
2019-11-19 15:41 ` Mark Wielaard
2019-11-19 16:13 ` Frank Ch. Eigler
2019-11-19 20:11 ` Mark Wielaard
2019-11-19 21:15 ` Frank Ch. Eigler
2019-11-20 11:53 ` Mark Wielaard
2019-11-20 12:29 ` Frank Ch. Eigler
2019-11-21 14:16 ` Mark Wielaard
2019-11-21 15:40 ` Mark Wielaard
2019-11-21 16:01 ` Frank Ch. Eigler
2019-11-21 15:58 ` Frank Ch. Eigler
2019-11-21 16:37 ` Mark Wielaard
2019-11-21 17:18 ` Frank Ch. Eigler
2019-11-21 20:42 ` Mark Wielaard
2019-11-22 12:08 ` Mark Wielaard
2019-11-14 20:45 ` Mark Wielaard
2019-11-15 11:03 ` Mark Wielaard
2019-11-15 21:00 ` Frank Ch. Eigler
2019-11-18 15:01 ` Mark Wielaard
2019-11-15 14:40 ` Mark Wielaard
2019-11-15 19:54 ` Frank Ch. Eigler
2019-11-18 15:31 ` Mark Wielaard
2019-11-18 15:49 ` Frank Ch. Eigler
2019-11-12 11:12 ` patch 1/2 debuginfod client Mark Wielaard
2019-11-12 15:14 ` Frank Ch. Eigler
2019-11-12 21:59 ` Mark Wielaard
2019-11-14 0:33 ` Frank Ch. Eigler
2019-11-15 21:33 ` Mark Wielaard
2019-11-12 21:25 ` Mark Wielaard
2019-11-13 23:25 ` Frank Ch. Eigler
2019-11-16 0:46 ` Mark Wielaard
2019-11-16 18:53 ` Frank Ch. Eigler
2019-11-18 17:17 ` Mark Wielaard
2019-11-18 20:33 ` Frank Ch. Eigler [this message]
2019-11-19 15:57 ` Mark Wielaard
2019-11-19 16:20 ` Frank Ch. Eigler
2019-11-19 20:16 ` Mark Wielaard
2019-11-19 21:22 ` Frank Ch. Eigler
2019-11-20 12:50 ` Mark Wielaard
2019-11-20 13:30 ` Frank Ch. Eigler
2019-11-21 14:02 ` Mark Wielaard
2019-11-13 13:57 ` Mark Wielaard
2019-11-14 11:24 ` Frank Ch. Eigler
2019-11-16 0:52 ` Mark Wielaard
2019-11-16 2:28 ` Frank Ch. Eigler
2019-10-30 11:04 ` patch 0/2 debuginfod submission Mark Wielaard
2019-10-30 13:40 ` Frank Ch. Eigler
2019-10-30 14:12 ` Mark Wielaard
2019-10-30 18:11 ` Frank Ch. Eigler
2019-10-31 11:18 ` Mark Wielaard
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