babeltrace2-sink.ctf.fs(7)
NAME
babeltrace2-sink.ctf.fs
— Babeltrace 2's file system CTF sink component class
DESCRIPTION
A Babeltrace 2 sink.ctf.fs component writes the messages it consumes to one or more CTF 1.8 traces on the file system.
+-------------+
| sink.ctf.fs |
| +--> CTF trace(s) on
Messages -->@ in | the file system
+-------------+
See babeltrace2-intro(7) to learn more about the Babeltrace 2 project and its core concepts.
A sink.ctf.fs component does not merge traces: it writes the messages of different input traces to different output traces.
Special trace IR to CTF translations
A sink.ctf.fs component makes a best effort to write CTF traces that are semantically equivalent to the input traces. As of this version, the component writes CTF 1.8 traces, so the following field class translations can occur:
-
The component translates a boolean field class to a CTF unsigned 8-bit integer field class.
The unsigned integer field’s value is 0 when the boolean field’s value is false and 1 when the boolean field’s value is true.
-
The component translates a bit array field to a CTF unsigned integer field class having the same length.
-
The component translates an option field class to a CTF variant field class where the options are an empty structure field class and the optional field class itself.
The empty structure field is selected when the option field has no field.
In all the cases above, the component adds a comment in the metadata stream, above the field class, to indicate that a special translation occurred.
Input message constraints
Because of limitations in CTF 1.8 regarding how discarded events and packets are encoded:
-
If a stream class supports discarded events and the
ignore-discarded-events
parameter is not true:-
The stream class must support packets.
-
Discarded events messages must have times.
-
Any discarded events message must occur between a packet end and a packet beginning message.
-
The beginning time of a discarded events message must be the same as the time of the last packet end message.
-
The end time of a discarded events message must be the same as the time of the next packet end message.
-
Time ranges of discarded events messages must not overlap.
-
-
If a stream class supports discarded packets and the
ignore-discarded-packets
parameter is not true:-
The stream class must support packets.
-
Discarded packets messages must have times.
-
The beginning time of a discarded events message must be the same as the time of the last packet end message.
-
The end time of a discarded events message must be the same as the time of the next packet beginning message.
-
Time ranges of discarded packets messages must not overlap.
-
The messages which a source.ctf.fs component creates satisfy all the requirements above.
If a discarded events or packets message has no events/packets count, the sink.ctf.fs component adds 1 to the corresponding CTF stream’s counter.
Alignment and byte order
A sink.ctf.fs component always aligns data fields as such:
- Integer fields with a size which is not a multiple of 8
-
1-bit.
- All other scalar fields (integer, enumeration, real, string)
-
8-bit.
The component writes fields using the machine’s native byte order. As of this version, there’s no way to force a custom byte order.
Output path
The path of a CTF trace is the directory which directly contains the metadata and data stream files.
The current strategy to build a path in which to write the streams of a given input trace is, in this order:
-
If the
assume-single-trace
parameter is true, then the output trace path to use for the single input trace is the directory specified by thepath
parameter. -
If the component recognizes the input trace as an LTTng (2.11 or greater) trace, then it checks specific trace environment values to build a trace path relative to the directory specified by the
path
parameter:- Linux kernel domain
-
HOST
/SNAME
-STIME
/kernel - User space domain, per-UID buffering
-
HOST
/SNAME
-STIME
/ust/uid/UID
/ARCHW
-bit - User space domain, per-PID buffering
-
HOST
/SNAME
-STIME
/ust/pid/PNAME
-PID
-PTIME
With:
-
HOST
-
Target’s hostname.
-
SNAME
-
Tracing session name.
-
STIME
-
Tracing session creation date/time.
-
UID
-
User ID.
-
ARCHW
-
Architecture’s width (
32
or64
). -
PNAME
-
Process name.
-
PID
-
Process ID.
-
PTIME
-
Process’s date/time.
-
If the input trace has a name, then the component sanitizes this name and uses it as a relative path to the directory specified by the
path
parameter.The trace name sanitization operation:
-
Replaces
.
subdirectories with_
. -
Replaces
..
subdirectories with__
. -
Removes any trailing
/
character.
-
-
The component uses the subdirectory
trace
relative to the directory specified by thepath
parameter.
In all the cases above, if the effective output trace path already exists on the file system, the component appends a numeric suffix to the name of the last subdirectory. The suffix starts at 0 and increments until the path does not exist.
INITIALIZATION PARAMETERS
-
assume-single-trace
=VAL
[optional boolean] -
If
VAL
is true, then assume that the component only receives messages related to a single input trace.This parameter affects how the component builds the output trace path (see Output path).
Default: false.
-
ignore-discarded-events
=VAL
[optional boolean] -
If
VAL
is true, then ignore discarded events messages.Default: false.
-
ignore-discarded-packets
=VAL
[optional boolean] -
If
VAL
is true, then ignore discarded packets messages.Default: false.
-
path
=PATH
[string] -
Base output path.
See Output path to learn how the component uses this parameter to build the output path for a given input trace.
-
quiet
=VAL
[optional boolean] -
If
VAL
is true, then do not write anything to the standard output.Default: false.
PORTS
+-------------+
| sink.ctf.fs |
| |
@ in |
+-------------+
Input
-
in
-
Single input port.