NAMEDESCRIPTION
InputTrace quirksMessage Interchange Protocol (MIP) specificsCTF compliance
INITIALIZATION PARAMETERSPORTS
Output
QUERY OBJECTS
babeltrace.support-infobabeltrace.trace-infosmetadata-info
SEE ALSO

babeltrace2-source.ctf.fs(7)

NAME

babeltrace2-source.ctf.fs — Babeltrace 2: File system CTF source component class

DESCRIPTION

A Babeltrace 2 source.ctf.fs message iterator reads one or more CTF 1.8 or CTF 2 data streams on the file system and emits corresponding messages.

CTF data streams on
the file system
  |
  |   +---------------------+
  |   |      src.ctf.fs     |
  |   |                     |
  '-->|    ...5c847 | 0 | 0 @--> Stream 0 messages
      |    ...5c847 | 0 | 1 @--> Stream 1 messages
      |    ...5c847 | 0 | 2 @--> Stream 2 messages
      +---------------------+

See babeltrace2-intro(7) to learn more about the Babeltrace 2 project and its core concepts.

Input

A source.ctf.fs component opens a single logical CTF trace. A logical CTF trace contains one or more physical CTF traces. A physical CTF trace on the file system is a directory which contains:

If the logical CTF trace to handle contains more than one physical CTF trace, then all the physical CTF traces, depending on the CTF version:

CTF 1.8

Must have a trace UUID and all UUIDs must be the same.

CTF 2

Must have a trace name and a trace unique ID (UID), and all trace namespaces (if any), names, and UIDs must be the same.

Opening more than one physical CTF trace to constitute a single logical CTF trace is needed to support LTTng’s tracing session rotation feature, for example (see lttng-rotate(1) starting from LTTng 2.11). In that case, the component elects the largest metadata stream, considering the total count of data stream classes and event record classes, as the one to use to decode the data streams of all the physical traces.

You specify which physical CTF traces to open and read with the inputs array parameter. Each entry in this array is the path to a physical CTF trace directory, that is, the directory directly containing the stream files.

A source.ctf.fs component doesn’t recurse into directories to find CTF traces. However, the component class provides the babeltrace.support-info query object which indicates whether or not a given directory looks like a CTF trace directory (see babeltrace.support-info).

The component creates one output port for each logical CTF data stream. More than one physical CTF data stream file can support a single logical CTF data stream (LTTng’s trace file rotation and tracing session rotation can cause this).

If two or more data stream files contain the same packets, then a source.ctf.fs message iterator reads each of them only once so that it never emits duplicated messages. This feature makes it possible, for example, to open overlapping LTTng snapshots with a single source.ctf.fs component and silently discard the duplicated packets.

Trace quirks

Many tracers produce CTF traces. A source.ctf.fs component makes some effort to support as many CTF traces as possible, even those with malformed streams.

In general, for a CTF 1.8 trace:

A source.ctf.fs component has special quirk handling for some LTTng and barectf traces, depending on the tracer version:

All LTTng versions

  • For CTF 1.8 traces, the component sets the origin of the monotonic clock class to the Unix epoch so that different LTTng traces are always correlatable.

    This is the equivalent of setting the force-clock-class-origin-unix-epoch parameter to true.

  • For a given data stream, for all the contiguous last packets of which the timestamp_end context field is 0, the message iterator uses the time of the last event record of the packet as the time of the packet end message.

    This is useful for the traces which lttng-crash(1) generates.

LTTng-UST up to, but excluding, 2.11.0
LTTng-modules up to, but excluding, 2.9.13
LTTng-modules from 2.10.0 to 2.10.9

  • For a given packet, the message iterator uses the time of the last event record of the packet as the time of the packet end message, ignoring the timestamp_end packet context field.

barectf up to, but excluding, 2.3.1

  • For a given packet, the message iterator uses the time of the first event record of the packet as the time of the packet beginning message, ignoring the timestamp_begin packet context field.

Message Interchange Protocol (MIP) specifics

A source.ctf.fs component can open and decode, depending on the effective MIP version:

MIP 0

CTF 1.8 traces.

MIP 1

CTF 1.8 and CTF 2 traces.

While the CTF 1.8 metadata stream (TSDL) features naturally map to the MIP 0 API and the CTF 2 ones to the MIP 1 API, a source.ctf.fs component makes a best effort to represent CTF 1.8 features when working with MIP 1. In particular, a source.ctf.fs component:

When reading a CTF 2 metadata stream (therefore working with MIP 1), a source.ctf.fs component:

CTF compliance

A source.ctf.fs component decodes traces as per CTF 1.8 or CTF 2, except:

INITIALIZATION PARAMETERS

clock-class-offset-ns=NS [optional signed integer]

Add NS nanoseconds to the offset of all the clock classes that the component creates.

You can combine this parameter with the clock-class-offset-s parameter.

clock-class-offset-s=SEC [optional signed integer]

Add SEC seconds to the offset of all the clock classes that the component creates.

You can combine this parameter with the clock-class-offset-ns parameter.

force-clock-class-origin-unix-epoch=VAL [optional boolean]

If VAL is true, then force the origin of all clock classes that the component creates to have a Unix epoch origin, whatever the detected tracer.

Default: false.

inputs=DIRS [array of strings]

Open and read the physical CTF traces located in DIRS.

Each element of DIRS is the path to a physical CTF trace directory containing the trace stream files.

All the specified physical CTF traces must belong to the same logical CTF trace. See Input to learn more about logical and physical CTF traces.

trace-name=NAME [optional string]

Set the name of the trace object that the component creates to NAME.

PORTS

+--------------------+
|     src.ctf.fs     |
|                    |
|   ...5c847 | 0 | 1 @
|                ... @
+--------------------+

Output

A source.ctf.fs component creates one output port for each logical CTF data stream. See Input to learn more about logical and physical CTF data streams.

Each output port name has one of the following forms:

TRACE-ID | STREAM-CLASS-ID | STREAM-ID
TRACE-ID | STREAM-ID

The component uses the second form when the stream class ID isn’t available.

TRACE-ID

If the namespace NS, name NAME, and UID UID of the trace are available, then the exact string: 

{namespace: `NS`, name: `NAME`, uid: `UID`}

If the namespace of the trace isn’t available, but the name NAME and UID UID are, then the exact string:

{name: `NAME`, uid: `UID`}

Otherwise, the absolute directory path of the trace.

NoteThe namespace of any LTTng trace is lttng.org,2009. If a CTF 1.8 trace has a UUID, then its corresponding libbabeltrace2 trace always has a name and a UID (the textual representation of the UUID).

STREAM-CLASS-ID

Stream class ID.

STREAM-ID

Stream ID if available, otherwise the absolute file path of the stream.

QUERY OBJECTS

babeltrace.support-info

See babeltrace2-query-babeltrace.support-info(7) to learn more about this query object.

For a directory input which is the path to a CTF trace directory, the result object contains:

weight

0.75

group

If the namespace NS, name NAME, and UID UID of the trace are available, then the exact string: 

namespace: NS, name: NAME, uid: UID

If the namespace of the trace isn’t available, but the name NAME and UID UID are, then the exact string:

name: NAME, uid: UID

Otherwise, the entry doesn’t exist.

NoteThe namespace of any LTTng trace is lttng.org,2009. If a CTF 1.8 trace has a UUID, then its corresponding libbabeltrace2 trace always has a name and a UID (the textual representation of the UUID).

You can leverage the group entry of this query object to assemble many physical CTF traces as a single logical CTF trace (see Input to learn more about logical and physical CTF traces). This is how the babeltrace2-convert(1) command makes it possible to specify as non-option arguments the paths to multiple physical CTF traces which belong to the same logical CTF trace and create a single source.ctf.fs component.

babeltrace.trace-infos

See babeltrace2-query-babeltrace.trace-infos(7) to learn more about this query object.

metadata-info

You can query the metadata-info object for a specific CTF trace to get its plain text metadata stream as well as whether or not it’s packetized.

Parameters:

path=PATH [string]

Path to the physical CTF trace directory which contains the metadata file.

Result object (map):

is-packetized [boolean]

True if the metadata stream file is packetized.

This is only relevant for a CTF 1.8 metadata stream. Always false with a CTF 2 metadata stream.

text [string]

Plain text metadata stream.

The exact contents of the metadata stream file for a CTF 2 metadata stream.

SEE ALSO

babeltrace2-intro(7), babeltrace2-plugin-ctf(7), lttng-crash(1)