[Gluster-devel] gfapi: add function to set client-pid

[Ravishankar N]

On 12/03/19 4:20 PM, Niels de Vos wrote:
> On Tue, Mar 12, 2019 at 03:00:27PM +0530, Ravishankar N wrote:
>> Hello,
>>
>> I'm planning to expose setting client-pid for gfapi clients via a new api,
>> something like `glfs_set_client_pid (fs, pid)`.
>> The functionality already exists for fuse mounts via the --client-pid=$PID
>> option, where the value is captured in
>> glusterfs_ctx_t->cmd_args->client_pid.
>>
>> Background:
>>
>> If the glusterfs eventing framework is enabled, AFR sends child-up/child
>> down events (via the gf_event() call) in the notify code path whenever there
>> is a connect/disconnect at AFR level. While this is okay for normal client
>> processes, it does not make much sense if the event is coming from say
>> glfsheal, which is a gfapi based program (having the AFR xlator) that is
>> invoked when you run the heal info set of commands. Many applications
>> periodically run heal info to monitor the heals and display it on the
>> dashboard (like tendryl), leading to a flood of child up/ down messages to
>> the application monitoring these events.
>>
>> We need to add a unique key=value to all such gf_event() calls in AFR, based
>> on which the consumer of the events can decide to ignore them if needed.
>> This key-value can be client-pid=$PID, where PID can be
>> GF_CLIENT_PID_SELF_HEALD for selfheal daemon, GF_CLIENT_PID_GLFS_HEAL for
>> glfsheal etc (these values are already defined in the code). This is why we
>> need a way to set the client-pid for gfapi clients as well.
>>
>> Another approach would be to add an xlator option (say 'client-name')
>> specific to AFR  and use that as the key-value pair but it seems to be an
>> overkill to do that just for the sake of eventing purposes. Besides, the pid
>> approach can also be extended to other gluster processes like rebalance, shd
>> and other daemons where AFR is loaded but AFR child-up/down events from it
>> are not of any particular interest.These daemons will now have to be spawned
>> by glusterd with the --client-pid option.
> Sounds good to me. This probably should be a function that is not
> available to all gfapi consumers, so please use api/src/glfs-internal.h
> for that. With clear documentation as written in the email, it should be
> obvious that only Gluster internal processes may use it.
>
> Adding the integration mailinglist on CC, as that is where all
> discussions around gfapi should be archived.
Hi Niels,
The gfapi patch [1] is awaiting your review.
Thanks,
Ravi
[1] https://review.gluster.org/#/c/glusterfs/+/22368/
>
> Thanks,
> Niels