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NAME | DESCRIPTION | INITIALIZATION PARAMETERS | PORTS | QUERY OBJECTS | BUGS | RESOURCES | AUTHORS | COPYRIGHT | SEE ALSO | COLOPHON |
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BABELTRACE2-SOURCE() BABELTRACE2-SOURCE()
babeltrace2-source.ctf.lttng-live - Babeltrace 2: LTTng live
source component class
A Babeltrace 2 source.ctf.lttng-live message iterator connects to
a local or remote LTTng (see <https://lttng.org/>) relay daemon,
receives the streams of a specific tracing session, and emits
corresponding messages.
CTF streams over
LTTng live (TCP)
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| +--------------------+
| | src.ctf.lttng-live |
'-->| |
| out @--> Sorted messages of one
+--------------------+ or more streams
More information about LTTng live is available in the LTTng
Documentation (see <https://lttng.org/docs/#doc-lttng-live>).
See babeltrace2-intro(7) to learn more about the Babeltrace 2
project and its core concepts.
A source.ctf.lttng-live component has a single output port: its
message iterator muxes (sorts) the messages from the various CTF
data streams internally.
A source.ctf.lttng-live message iterator handles the messages of
one, and only one LTTng tracing session. A single LTTng tracing
session can contain one or more traces, depending on the active
tracing domains and the configured user space buffering scheme.
The component connects to an LTTng relay daemon using the inputs
parameter. This is an array of exactly one string which is the URL
of the LTTng relay daemon to connect to.
By default, if the remote tracing session name doesn’t exist, then
the message iterator returns "try again later". This default mode
makes the message iterator never end: even if the remote tracing
session is destroyed, the message iterator keeps on waiting for a
tracing session with the same name to exist. You can change this
behaviour with the session-not-found-action initialization
parameter.
Note
As of this version, you can only create one message iterator
per source.ctf.lttng-live component. This is because the LTTng
live protocol accepts at most one client per tracing session
per LTTng relay daemon.
As of this version, a source.ctf.lttng-live component can connect
to an LTTng relay daemon using the LTTng 2.4 or LTTng 2.15
protocol. The latter is required for CTF 2 (see
<https://diamon.org/ctf/>) support.
The "get supported MIP versions" method of source.ctf.lttng-live
always reports to support MIP versions 0 and 1. If you attempt to
make a source.ctf.lttng-live component read a CTF 2 recording
session within a trace processing graph configured with MIP 0,
then the message iterator will fail at initialization or "next"
method call time.
inputs=URL [array of one string]
Use URL to connect to the LTTng relay daemon.
URL is an array of exactly one string of which the format is:
net[4]://RDHOST[:RDPORT]/host/TGTHOST/SESSION
RDHOST
Host name or IP address of the LTTng relay daemon.
RDPORT
Listening port of the LTTng relay daemon.
If not specified, then the component uses the default port
(5344).
TGTHOST
Target host name or IP address.
SESSION
Name of the LTTng tracing session from which to receive
data.
session-not-found-action=(continue | fail | end) [optional string]
When the message iterator doesn’t find the specified remote
tracing session (SESSION part of the inputs parameter), do one
of:
continue (default)
Keep on trying, returning "try again later" to the
downstream user until the tracing session exists.
With this action, the message iterator never ends, as the
LTTng live protocol cannot currently indicate that a
tracing session will never exist.
fail
Fail.
end
End.
+--------------------+
| src.ctf.lttng-live |
| |
| out @
+--------------------+
Output
out
Single output port.
babeltrace.support-info
See babeltrace2-query-babeltrace.support-info(7) to learn more
about this query object.
For a string input which honors the LTTng live URL format (see the
inputs parameter), the result object is 0.75.
sessions
You can query the sessions object to get a list of available LTTng
tracing sessions for a given LTTng relay daemon URL.
Parameters:
url=URL [string]
Use URL to connect to the LTTng relay daemon.
The format of URL is:
net[4]://RDHOST[:RDPORT]
RDHOST
Host name or IP address of the LTTng relay daemon.
RDPORT
Listening port of the LTTng relay daemon.
If not specified, then the query operation uses the
default port (5344).
Result object (array of maps, one element for each available
tracing session):
client-count [unsigned integer]
Current number of LTTng live clients connected to the relay
daemon to receive data from this tracing session.
session-name [string]
Tracing session name.
stream-count [unsigned integer]
Current number of CTF streams in this tracing sessions,
including the metadata streams.
target-hostname [string]
Hostname of the tracing session.
This isn’t necessarily the hostname of the relay daemon.
timer-us [unsigned integer]
Configured period (µs) of the live timer of the tracing
session (see lttng-create(1)).
trace-format [string]
Format of the trace(s) of the tracing session amongst:
ctf-1.8
CTF 1.8 (see <https://diamon.org/ctf/v1.8.3/>)
ctf-2.0
CTF 2 (see <https://diamon.org/ctf/>)
url [string]
URL to use as the first element of the inputs parameter to
connect to the same LTTng relay daemon and receive data from
this tracing session.
If you encounter any issue or usability problem, please report it
on the Babeltrace bug tracker (see
<https://bugs.lttng.org/projects/babeltrace>).
The Babeltrace project shares some communication channels with the
LTTng project (see <https://lttng.org/>).
• Babeltrace website (see <https://babeltrace.org/>)
• Mailing list (see <https://lists.lttng.org>) for support and
development: [email protected]
• IRC channel (see <irc://irc.oftc.net/lttng>): #lttng on
irc.oftc.net
• Bug tracker (see <https://bugs.lttng.org/projects/babeltrace>)
• Git repository (see
<https://git.efficios.com/?p=babeltrace.git>)
• GitHub project (see <https://github.com/efficios/babeltrace>)
• Continuous integration (see
<https://ci.lttng.org/view/Babeltrace/>)
• Code review (see
<https://review.lttng.org/q/project:babeltrace>)
The Babeltrace 2 project is the result of hard work by many
regular developers and occasional contributors.
The current project maintainer is Jérémie Galarneau
<mailto:[email protected]>.
This component class is part of the Babeltrace 2 project.
Babeltrace is distributed under the MIT license (see
<https://opensource.org/licenses/MIT>).
babeltrace2-intro(7), babeltrace2-plugin-ctf(7), lttng-relayd(8),
lttng-create(1)
This page is part of the babeltrace (trace read and write
libraries and a trace converter) project. Information about the
project can be found at ⟨http://www.efficios.com/babeltrace⟩. If
you have a bug report for this manual page, send it to
[email protected]. This page was obtained from the
project's upstream Git repository
⟨git://git.efficios.com/babeltrace.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-06-25.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
BABELTRACE2-SOURCE()
Pages that refer to this page: babeltrace2(1), babeltrace2-convert(1), babeltrace2-plugin-ctf(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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