= YAML trace type object

A _**trace type object**_ is the type of a xref:trace-obj.adoc[trace
object].

A trace type describes everything a CTF consumer needs to decode all the
trace's xref:how-barectf-works:ctf-primer.adoc#ds[data
streams].

A trace type object is only found as the
xref:trace-obj.adoc#type-prop[`type` property] of a trace object.

[[props]]
== Properties

[%autowidth.stretch, cols="d,d,a,d,d", role="can-break"]
|===
|Name |Type |Description |{req-abbr} |Default

|[[native-bo-prop]]`native-byte-order`
|xref:common-values.adoc#byte-order[Byte order]
|Native byte order of the system which produces this trace type's
instance's xref:how-barectf-works:ctf-primer.adoc#ds[data streams].

You must not use this property and the
<<trace-bo-prop,`trace-byte-order`>> property at the same time.
|Yes, if the `trace-byte-order` property is missing
|

|[[trace-bo-prop]]`trace-byte-order`
|xref:common-values.adoc#byte-order[Byte order]
|Byte order of fields of this trace type's
instance's xref:how-barectf-works:ctf-primer.adoc#ds[data streams].

[IMPORTANT]
====
This property exists to support barectf{nbsp}2 configurations.

Prefer the <<native-bo-prop,`native-byte-order`>> property instead, as
enforcing the trace byte order could result in a less efficient
generated tracer.
====

You must not use this property and the `native-byte-order` property at
the same time.
|Yes, if the `native-byte-order` property is missing
|

|[[uuid-prop]]`uuid`
|xref:common-values.adoc#uuid[UUID] or string
|UUID of this trace type.

If this property's value is the string `auto`, barectf generates a UUID.

|No
|No UUID

|[[ft-aliases-prop]]`$field-type-aliases`
|Mapping of string keys to xref:ft-obj.adoc[field type objects]
or strings
|Field type aliases.

Keys of this mapping are field type alias names.

If an entry's value is a string, it must be the name of an existing
field type alias.

You can use a field type alias name anywhere you can use a
xref:ft-obj.adoc[field type object].
|No
|Empty mapping

|[[ll-aliases-prop]]`$log-level-aliases`
|Mapping of string keys to integers
|Log level aliases.

Keys of this mapping are log level alias names.

Values of this mapping are positive integral log levels.

You can use a log level alias name as the value of an event record type
object's xref:ert-obj.adoc#ll-prop[`log-level` property].
|No
|Empty mapping

|`$features`
|<<features-obj>>
|Features of this trace type's instance (trace).
|No
|See <<features-obj>> for default values.

|[[clk-types-prop]]`clock-types`
|Mapping of string keys to xref:clk-type-obj.adoc[clock type objects]
|Clock type store for this trace type.

Keys of this mapping are clock type names. They must be valid
xref:index.adoc#tsdl-ident[TSDL identifiers].

The
xref:dst-obj.adoc#def-clk-type-name-prop[`$default-clock-type-name`
property] of a data stream type object refers to a key of this mapping.
|No
|No clock type store

|[[dsts-prop]]`data-stream-types`
|Mapping of string keys to xref:dst-obj.adoc[data stream
type objects]
|Data stream types of this trace type.

Keys of this mapping are data stream type names. They must be valid
C{nbsp}identifiers.

This mapping must contain at least one entry.
|Yes
|

|[[include-prop]]`$include`
|Sequence of strings.
|See xref:include.adoc[].
|No
|No inclusions
|===

[[features-obj]]
== Features object

The features of a trace type object.

As of barectf{nbsp}{page-component-version}, each feature controls
whether or not some information will be part of the header of each
xref:how-barectf-works:ctf-primer.adoc#pkt[CTF packet] which the
generated tracer produces.

You can enable or disable a feature. When you enable one, you can set
its xref:ft-obj.adoc[field type] explicitly or make barectf choose a
sane default.

=== Properties

For all the feature properties below, if the value is a boolean:

True::
    Make barectf use a default field type.

False::
    Disable the feature.

All the properties are optional.

[%autowidth.stretch, cols="d,d,a,d", role="can-break"]
|===
|Name |Type |Description |Default

|[[magic-ft-prop]]`magic-field-type`
|32-bit{nbsp}unsigned xref:int-ft-obj.adoc[integer field type object],
string, or boolean
|Type of packet header's magic number field.

If this property's value is a string, it must be the name of an existing
<<ft-aliases-prop,field type alias>>.
|Use a default field type (true)

|[[uuid-ft-prop]]`uuid-field-type`
|xref:static-array-ft-obj.adoc[Static array field type object] of
16{nbsp}8-bit{nbsp}unsigned xref:int-ft-obj.adoc[integer field
type objects] (8-bit{nbsp}alignment), string, or boolean
|Type of packet header's trace type UUID field.

If this property's value is a string, it must be the name of an existing
<<ft-aliases-prop,field type alias>>.
|Use a default field type (true) if this trace type has a
<<uuid-prop,`uuid` property>>, or false otherwise

|[[dst-id-ft-prop]]`data-stream-type-id-field-type`
|Unsigned xref:int-ft-obj.adoc[integer field type object], string,
or boolean
|Type of packet header's xref:dst-obj.adoc[data stream type] ID field.

If this property's value is a string, it must be the name of an existing
<<ft-aliases-prop,field type alias>>.

This feature is required when this trace type has more than one
data stream type (<<dsts-prop,`data-stream-types` property>>).
|Use a default field type (true)
|===

== Examples

NOTE: The following examples can omit <<dsts-prop,data stream type
objects>> for clarity.

.Basic trace type object.
====
[source,yaml]
----
native-byte-order: little-endian
data-stream-types:
  # ...
----
====

.Trace type object with a specific <<uuid-prop,UUID>>.
====
[source,yaml]
----
native-byte-order: little-endian
uuid: 1b706833-b56c-4960-b5f7-e43651ff01fb
data-stream-types:
  # ...
----
====

.Trace type object with an automatic <<uuid-prop,UUID>>.
====
[source,yaml]
----
native-byte-order: little-endian
uuid: auto
data-stream-types:
  # ...
----
====

.Trace type object with a disabled <<magic-ft-prop,magic field type feature>>.
====
[source,yaml]
----
native-byte-order: little-endian
$features:
  magic-field-type: false
data-stream-types:
  # ...
----
====

.Trace type object with a specific <<dst-id-ft-prop,data stream type ID field type feature>>.
====
[source,yaml]
----
native-byte-order: little-endian
$features:
  data-stream-type-id-field-type:
    class: unsigned-integer
    size: 8
data-stream-types:
  # ...
----
====

.Trace type object with a <<clk-types-prop,clock type object>>.
====
[source,yaml]
----
native-byte-order: little-endian
clock-types:
  sys_clock:
    frequency: 8000000
    description: Clock A13 (8 MHz)
    origin-is-unix-epoch: false
data-stream-types:
  my_stream:
    $default-clock-type-name: sys_clock
    # ...
  # ...
----
====

.Trace type object with <<ft-aliases-prop,field type aliases>>.
====
[source,yaml]
----
native-byte-order: little-endian
$field-type-aliases:
  hex-uint8:
    $inherit: uint8
    preferred-display-base: hexadecimal
  string-array:
    class: dynamic-array
    element-field-type:
      class: string
$features:
  magic-field-type: hex-uint8
data-stream-types:
  my_stream:
    event-record-types:
      my_event:
        payload-field-type:
          client_id: hex-uint8
          messages: string-array
      # ...
    # ...
  # ...
----
====

.Trace type object with a <<ll-aliases-prop,log level alias>>.
====
[source,yaml]
----
native-byte-order: little-endian
$log-level-aliases:
  WARN: 17
data-stream-types:
  my_stream:
    event-record-types:
      my_event:
        log-level: WARN
        # ...
      # ...
    # ...
  # ...
----
====

.Trace type object with <<include-prop,inclusions>>.
====
[source,yaml]
----
native-byte-order: little-endian
data-stream-types:
  # ...
$include:
  - stdint.yaml
  - stdmisc.yaml
  - network-field-type-aliases.yaml
  - sched-field-type-aliases.yaml
  - default-log-levels.yaml
  - project-b-data-stream-types.yaml
----
====