[SSSD] About managing branches: WAS: [Fwd: Re: [PATCH] nss: Add option to disable memcache]

Sumit Bose sbose at redhat.com
Mon Sep 16 08:29:41 UTC 2013


On Fri, Sep 13, 2013 at 12:41:41PM -0400, Simo Sorce wrote:
> I wonder if it wouldn't make sense to delay commits to stable branches
> until the time to release comes ?
> 
> Would it make it easier or harder to review and apply changes only at
> release time ?

I think it would be harder. Since some patches cannot easily be
cherry-pick but needs explicit backporting chances are that there are
conflicts which all have to be sorted out at release time, making the
release process more cumbersome.

I guess it is more likely that a patch will be forgotten.

If we commit the patches when they are available chances are higher that
the branch is tested at least by some developers while preparing other
patches for this branch.

bye,
Sumit

> 
> Simo.
> 
> -- 
> Simo Sorce * Red Hat, Inc * New York

> Date: Fri, 13 Sep 2013 17:59:04 +0200
> From: Jakub Hrozek <jhrozek at redhat.com>
> To: sssd-devel at lists.fedorahosted.org
> Subject: Re: [SSSD] [PATCH] nss: Add option to disable memcache
> 
> On Fri, Sep 13, 2013 at 05:26:23PM +0200, Jakub Hrozek wrote:
> > On Fri, Sep 13, 2013 at 02:31:50PM +0200, Michal Židek wrote:
> > > On 09/12/2013 10:10 PM, Simo Sorce wrote:
> > > >On Thu, 2013-09-12 at 20:06 +0200, Michal Židek wrote:
> > > >>On 09/12/2013 05:48 PM, Simo Sorce wrote:
> > > >>>On Thu, 2013-09-12 at 11:23 +0200, Jakub Hrozek wrote:
> > > >>>>On Wed, Sep 11, 2013 at 05:54:01PM -0400, Simo Sorce wrote:
> > > >>>>>On Wed, 2013-09-11 at 20:19 +0200, Michal Židek wrote:
> > > >>>>>>Hello,
> > > >>>>>>
> > > >>>>>>I would like to have this option in SSSD for debugging purposes.
> > > >>It is
> > > >>>>>>not documented, so it should be invisible for users (but I can
> > > >>add it to
> > > >>>>>>man pages as well, if someone thinks it is useful to have it
> > > >>there).
> > > >>>>>
> > > >>>>>This would cause you to have stale mmap cache files on the system,
> > > >>>>>wouldn't it make more sense to have an environment variable for
> > > >>the
> > > >>>>>client libraries instead and have them ignore the mmap cache when
> > > >>you
> > > >>>>>want to test something ?
> > > >>>>
> > > >>>>This sounds like a good idea.
> > > >>>>
> > > >>>>>It could also be documented as it may be a useful workaround
> > > >>should a
> > > >>>>>user find a bug that hits the mmap_cache and wants a temporary way
> > > >>to
> > > >>>>>avoid it even if with performance penalty for a specific
> > > >>application.
> > > >>>>>
> > > >>>>>Something like SSS_NSS_USE_MEMCACHE=yes/no
> > > >>>>>
> > > >>>>>defaulting to yes, if no env var is found.
> > > >>
> > > >>Just found out that we have a check for _SSS_MC_SPECIAL in function
> > > >>sss_nss_mc_get_ctx. It makes the function fail returning the EPERM
> > > >>errno. I do not know what was the purpose of this variable, but it is
> > > >>exactly what we need.
> > > >>
> > > >>Maybe we should just rename this variable, because it is not cleat
> > > >>from
> > > >>first glance, what it really does (see attached patch).
> > > >
> > > >Uhmmm I forgot why I added it, I guess for testing :)
> > > >
> > > >>>>
> > > >>>>If I can speak for Michal -- we discussed that it might be nice to
> > > >>be able
> > > >>>>to temporarily disable the memcache somehow, but if there was a
> > > >>documented
> > > >>>>way, hitting memcache problems would simply disable it and don't
> > > >>even
> > > >>>>report a bug. Kind of like users switching SELinux to Permissive.
> > > >>>
> > > >>>Their choice.
> > > >>>I think it is more valuable to have the option than not for fear of
> > > >>>people not reporting bugs.
> > > >>>
> > > >>
> > > >>Ok. I added the man page change in the second patch.
> > > >>
> > > >>>Simo.
> > > >>>
> > > >>
> > > >>Patches are attached.
> > > >>
> > > >>Thanks
> > > >>Michal
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>differences
> > > >>between files
> > > >>attachment
> > > >>(0001-Rename-_SSS_MC_SPECIAL.patch)
> > > >>
> > > >> From 595c9892ad2079276855519e1fac086b9d52f685 Mon Sep 17 00:00:00 2001
> > > >>From: Michal Zidek <mzidek at redhat.com>
> > > >>Date: Thu, 12 Sep 2013 19:45:39 +0200
> > > >>Subject: [PATCH 1/2] Rename _SSS_MC_SPECIAL
> > > >>
> > > >>If the environment variable _SSS_MC_SPECIAL is set to "NO", the
> > > >>mmap cache is skipped in the client code. The name is not very
> > > >>descriptive. This patch renames the variable to SSS_NSS_USE_MEMCACHE.
> > > >>---
> > > >>  src/sss_client/nss_mc_common.c | 4 ++--
> > > >>  1 file changed, 2 insertions(+), 2 deletions(-)
> > > >>
> > > >>diff --git a/src/sss_client/nss_mc_common.c
> > > >>b/src/sss_client/nss_mc_common.c
> > > >>index 5d36c47..a0a70ab 100644
> > > >>--- a/src/sss_client/nss_mc_common.c
> > > >>+++ b/src/sss_client/nss_mc_common.c
> > > >>@@ -108,8 +108,8 @@ errno_t sss_nss_mc_get_ctx(const char *name,
> > > >>struct sss_cli_mc_ctx *ctx)
> > > >>      char *envval;
> > > >>      int ret;
> > > >>
> > > >>-    envval = getenv("_SSS_MC_SPECIAL");
> > > >>-    if (envval && strcmp(envval, "NO") == 0) {
> > > >>+    envval = getenv("SSS_NSS_USE_MEMCACHE");
> > > >>+    if (envval && strcasecmp(envval, "NO") == 0) {
> > > >>          return EPERM;
> > > >>      }
> > > >>
> > > >>--
> > > >>1.7.11.2
> > > >
> > > >ACK
> > > >
> > > >
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>
> > > >>differences
> > > >>between files
> > > >>attachment
> > > >>(0002-man-sssd-Add-note-about-SSS_NSS_USE_MEMCACHE.patch)
> > > >>
> > > >> From f7d07757b00eec75716ae7b43403f206d81466b6 Mon Sep 17 00:00:00 2001
> > > >>From: Michal Zidek <mzidek at redhat.com>
> > > >>Date: Thu, 12 Sep 2013 19:51:55 +0200
> > > >>Subject: [PATCH 2/2] man sssd: Add note about SSS_NSS_USE_MEMCACHE
> > > >>
> > > >>---
> > > >>  src/man/sssd.8.xml | 8 ++++++++
> > > >>  1 file changed, 8 insertions(+)
> > > >>
> > > >>diff --git a/src/man/sssd.8.xml b/src/man/sssd.8.xml
> > > >>index 0aba418..3a0fc01 100644
> > > >>--- a/src/man/sssd.8.xml
> > > >>+++ b/src/man/sssd.8.xml
> > > >>@@ -187,6 +187,14 @@
> > > >>          </variablelist>
> > > >>      </refsect1>
> > > >>
> > > >>+    <refsect1 id='notes'>
> > > >>+        <title>NOTES</title>
> > > >>+        <para>
> > > >>+            If the environment variable SSS_NSS_USE_MEMCACHE is set
> > > >>to "NO",
> > > >>+            the client applications will not use the fast in memory
> > > >
> > > >drop 'the' --^^^^ in front of client
> > > >
> > > >otherwise ACK
> > > >
> > > >>  cache.
> > > >>+        </para>
> > > >>+    </refsect1>
> > > >>+
> > > >>         <xi:include xmlns:xi="http://www.w3.org/2001/XInclude"
> > > >>href="include/seealso.xml" />
> > > >>
> > > >>  </refentry>
> > > >>--
> > > >>1.7.11.2
> > > 
> > > Thank you. New patches are attached.
> > > 
> > > Michal
> > 
> > The language was fixed as Simo requested. ACK.
> > 
> > I think this would be nice to have even in stable branches.
> 
> Pushed to master, sssd-1-11, sssd-1-10 and sssd-1-9
> 
> I'm looking forward to releasing 1.10.2 to have one less branch to care
> about :-)
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