[lttng-dev] Max length for trace path in LTTng MI

Tue Mar 29 17:44:28 UTC 2016

Hi,

We have noticed a problem when a trace session uses a long output path (over 255 in length) and the session is listed with MI. The MI output format is specified in a schema, here is the relevant part:

<!-- Maps to the char name[LTTNG_SYMBOL_NAME_LEN] -->
<xs:simpleType name="name_type">
<xs:restriction base="xs:string">
<xs:maxLength value="255"/>
</xs:restriction>
</xs:simpleType>

Because of the maxLength of 255, the MI output received by the viewer (Trace Compass) is deemed invalid and the session cannot be listed.

The issue was first noticed here, in a test:
https://ci.lttng.org/view/Trace%20Compass/job/tracecompass-master-linux/197/JAVA_TO_USE=OpenJDK-8,SWT_GTK3=0,WM=metacity,label=x86-32,target-platform=tracecompass-e4.5/artifact/lttng/org.eclipse.tracecompass.lttng2.control.ui.swtbot.tests/target/work/data/.metadata/.log/*view*/

Then I described steps to reproduce this in normal usage:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=490557

What would be the best way forward here? Would it be a solution to increase this limit or would it be better perhaps to have a different element for the trace output path that has either a bigger limit or no limit at all?

Thank you,
Marc-André
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.lttng.org/pipermail/lttng-dev/attachments/20160329/93af1623/attachment.html>