[ltt-dev] [RFC UST and LTTNG] Daemon model proposal v0.3

David Goulet david.goulet at polymtl.ca
Mon Jan 31 14:16:01 EST 2011

On 11-01-31 02:06 PM, Mathieu Desnoyers wrote:
> * David Goulet (david.goulet at polymtl.ca) wrote:
>> Everything about a per-user ltt-sessiond will be added to the RFC!
>> Comments below.
>> On 11-01-31 12:10 PM, Mathieu Desnoyers wrote:
>>> * David Goulet (david.goulet at polymtl.ca) wrote:
>>>> This unique identifier SHOULD be a unique string consisting of the username, a
>>>> session name and the number of already created session plus one. The last
>>>> number makes sure that the ID is unique in the ltt-sessiond context. In the
>>>> implementation, a simple number could be use for performance purpose instead of
>>>> comparing string at each iteration.
>>>> Ex: Username - "dave", Session name - "mysession", Num. sessions - fifth one
>>>>       -->   ID: dave.mysession-5
>>> We will run into problems across reboots: session IDs might be reused, thus
>>> trying to overwrite older traces. Other ideas, possibly including UUID, would be
>>> welcome.
>> Across reboot... I don't see the problem reusing IDs... The only problem
>> to overwrite older traces is if the session ID is used in the trace path
>> on the disk which is not the case.
> Then what do you propose using as directory name to hold the trace on disk ?
> Using the session name would seem natural.

Yep, absolutely for the first level directory but the trace file path 
should be quite different. We talked about something like this the other 
day :


having $sessionID the above proposition : dave.session_name-5

The $time is a bit useless but makes the trace path "unique" since the 
case of having the same date, appname and PID can occur.

I'm actually quite open for better suggestion :)

I'll make sure the rest of that email is taking into account for the 
next version!


David Goulet
LTTng project, DORSAL Lab.

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