[sheepdog] [PATCH v2 4/4] cluster driver: handle pending block/notify event during reconnect

[Kai Zhang]

On Jul 9, 2013, at 8:46 AM, MORITA Kazutaka <morita.kazutaka at gmail.com> wrote:

> At Sun,  7 Jul 2013 21:20:51 -0700,
> Kai Zhang wrote:
>> 
>> Current implementation of reconnection doesn't handle pending block/notify
>> event.
>> 
>> It is easy to handle notify event by sending it again.
>> 
>> However, it is a little bit complex for block event.
>> This is because a block event need 4 steps.
>> 1. in queue_cluster_request(), send block event by sys->cdrv->block(), and
>>  add to pending_block_list.
>> 2. in sd_block_handler(), queue the event to work queue of 'block' thread.
>> 3. in cluster_op_done(), send unblock event by sys->cdrv->unblock().
>> 4. in sd_notify_handler(), remove it from pending_block_list.
>> 
>> And step 1 and 3 contains broadcast operations.
>> So we have to know which step has been done for a pending block event.
>> 
>> If step 1 has been done, we can re-queue it simply. (Any block event which sent
>> by this node have been removed due to the leave event)
>> If step 2 has been done, the event is handling by another thread. We have to mark
>> it as 'drop' so that it will be dropped when cluster_op_done() is called later.
>> if step 3 has been done, we should call sd_notify_handler() manually to finish
>> it.
>> 
>> Signed-off-by: Kai Zhang <kyle at zelin.io>
>> ---
>> sheep/group.c      |   69 ++++++++++++++++++++++++++++++++++++++++++++++++++--
>> sheep/sheep_priv.h |    8 ++++++
>> 2 files changed, 75 insertions(+), 2 deletions(-)
>> 
>> diff --git a/sheep/group.c b/sheep/group.c
>> index 2fa4091..1a549de 100644
>> --- a/sheep/group.c
>> +++ b/sheep/group.c
>> @@ -251,6 +251,9 @@ static void cluster_op_done(struct work *work)
>> 	struct vdi_op_message *msg;
>> 	size_t size;
>> 
>> +	if (req->status == REQUEST_DROPPED)
> 
> I think adding sd_dprintf here would help us to debug.
> 

We already have a sd_dprintf when we mark it as REQUEST_DROPPED.
Do you think we should add one more here?

Thanks,
Kyle

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