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Date: Sun, 11 Jan 2015 10:00:40 -0800
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Subject: Re: Help with what I am doing wrong with the C interface ...
From: Richard Sharpe <realrichardsharpe@gmail.com>
To: user@zookeeper.apache.org
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On Sun, Jan 11, 2015 at 9:59 AM, Richard Sharpe
<realrichardsharpe@gmail.com> wrote:
> Hi folks,
>
> I am not sure if this is the correct interface, however, I am trying
> to develop a config backend for Samba that connects to Zookeeper. The
> intent is that parts of Samba's smb.conf would be stored in zookeeper
> to make life easier in clustered environments.
>
> I am constrained to use C both by the code I am working with and by
> inclination. The examples in C are somewhat sparse.
>
> I am trying to use the sync interface at the moment and I get zero
> children back when I call zoo_get_children, however, if I use cli_mt I
> can see that there is one child node under /samba in zookeeper:
>
>     [root@localhost zookeeper-3.4.6]# ./src/c/cli_mt localhost:2181
>     Watcher SESSION_EVENT state =3D CONNECTED_STATE
>     Got a new session id: 0x14accb10de10004
>
>     ls /
>     time =3D 1 msec
>     /: rc =3D 0
>     samba
>     zookeeper
>     time =3D 1 msec
>     ls /samba
>     time =3D 1 msec
>     /samba: rc =3D 0
>     global
>     time =3D 1 msec
>
> I am pretty certain that I am asking for the children of /samba as my
> logging code shows me that I am feeding that path to zoo_get_children
> and when I had a bug that appended a trailing slash I got error -8
> back.
>
> Here are what I think are the relevant parts of the code I have at the mo=
ment:
>
> -------
> static void zoo_watcher(zhandle_t *zzh, int type, int state, const char *=
path,
>                         void *context)
> {
>         DEBUG(10, ("%s called\n",__func__));
> }
>
> ...
>
>         zh =3D zookeeper_init(host_port, zoo_watcher, 30000, &myId, 0, 0)=
;
>         if (!zh) {
>                 DEBUG(10, ("Problem with zookeeper_init: %s\n",
> strerror(errno)));
>         }
>
> ...
>
>         struct String_vector strings;
> ...
>
>         rc =3D zoo_get_children(zh, zookeeper_key, false, &strings);
> --------------
>
> There are hints in the test code for the C client interface that
> perhaps I should be doing something real in the watcher function above
> but I am not sure.
>
> Any hints would be appreciated.

OK, it looks like the problem was my confusion between the single
threaded library and the multi-threaded library.

I was trying to use the _st library, but it seems I need more
infrastructure for that.

I wrote a small simple test program and after linking it with the _mt
library things are working.

--=20
Regards,
Richard Sharpe
(=E4=BD=95=E4=BB=A5=E8=A7=A3=E6=86=82=EF=BC=9F=E5=94=AF=E6=9C=89=E6=9D=9C=
=E5=BA=B7=E3=80=82--=E6=9B=B9=E6=93=8D)