Re: SoC: Improve syslogd

["Rainer Gerhards" <rgerhards%gmail.com@localhost>]

I could do a quick test. Unfortunately, it does not work. You will
always see EAGAIN - no matter if the underlying connection is broken
or not. While on the road, I did also think about this method. From a
theoretical point of view, I think it can not work.  I'll elaborate a
bit later as I need to head to the next meeting (I just found time to
squeeze the quick test into today's busy schedule...).

Rainer

On Thu, May 29, 2008 at 9:23 AM, Rainer Gerhards 
<rgerhards%gmail.com@localhost> wrote:
> I thought a bit about the approach, I think there is a race condition
> in it, even if it works. Quick summary here:
> http://blog.gerhards.net/2008/05/more-reliability-for-tcp-syslog.html
>
> Rainer
>
> On Thu, May 29, 2008 at 9:02 AM, Rainer Gerhards 
> <rgerhards%gmail.com@localhost> wrote:
>> So far just one reply, the others follow (but I need to leave soon
>> until later ;)):
>>
>> On Thu, May 29, 2008 at 1:45 AM, Martin Schütte 
>> <info%mschuette.name@localhost> wrote:
>>>> this can lead to massive data loss, even to complete data loss. Note
>>>> that this is not a direct cause of transport-tls, but of the underlying
>>>> plain TCP syslog protocol. I have more details in my blog post on the
>>>> unreliability of TCP syslog.
>>>
>>> I also thought about that message loss and I think I found a solution.
>>> Please take a look at
>>> http://mschuette.name/wp/2008/05/29/reliable-tcp-reconnect-made-easy/ and
>>> let me know what you think.
>>
>> I think this is a nice but partial solution. Note: I did not yet prove
>> what I am talking about ;), but.. As of my understanding of TCP, this
>> does not (actually MUST not) work if the connection really breaks
>> (that is remote machine or network connection dies). In this case, you
>> do not have a real shutdown.
>>
>> For the TLS use case, however, this should be sufficient (as we always
>> have a connection close, at least if nothing goes strangly wrong).
>>
>> But the shutdown case should work. I'll give it a try and report back.
>>
>> Thanks for the good idea!
>>
>> Rainer
>>
>