3eceaf4669
Bug: b/258408932 Change-Id: Ib96f39fe0c3912f9746bcc09d079097a145d6115 Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/290987 Reviewed-by: Harald Alvestrand <hta@webrtc.org> Commit-Queue: Artem Titov <titovartem@webrtc.org> Cr-Commit-Position: refs/heads/main@{#39205}
46 lines
2.0 KiB
Markdown
46 lines
2.0 KiB
Markdown
<!-- go/cmark -->
|
|
<!--* freshness: {owner: 'lndmrk' reviewed: '2022-06-23'} *-->
|
|
|
|
# Field trials
|
|
|
|
WebRTC provides some means to alter its default behavior during run-time,
|
|
colloquially known as *field trials*. This is foremost used for A/B testing new
|
|
features and are related to
|
|
[Chromium field trials](https://chromium.googlesource.com/chromium/src/+/main/testing/variations/README.md)
|
|
to facilitate interoperability.
|
|
|
|
A field trial consist of a key-value pair of strings. By convention, the field
|
|
trial key is prefixed with `WebRTC-` and each word is capitalized without
|
|
spaces. Sometimes the key is further subdivided into a category, for example,
|
|
`WebRTC-MyCategory-MyExperiment`. The field trial value is an opaque string and
|
|
it is up to the author to define what it represents. There are
|
|
[helper functions](https://webrtc.googlesource.com/src/+/refs/heads/main/api/field_trials_view.h)
|
|
to use a field trial as a boolean, with the string `Enabled` representing true
|
|
and `Disabled` representing false. You can also use
|
|
[field trial parameters](https://webrtc.googlesource.com/src/+/refs/heads/main/rtc_base/experiments/field_trial_parser.h)
|
|
if you wish to encode more elaborate data types.
|
|
|
|
The set of field trials can be instantiated from a single string with the format
|
|
`<key-1>/<value-1>/<key-2>/<value-2>/`. Note the final `/` at the end! In
|
|
Chromium you can launch with the `--force-fieldtrials` flag to instantiate field
|
|
trials this way, for example:
|
|
|
|
```
|
|
--force-fieldtrials="WebRTC-Foo/Enabled/WebRTC-Bar/Disabled/"
|
|
```
|
|
|
|
## Policy
|
|
|
|
The policy for field trials is:
|
|
|
|
- A field trial should only be used to test out new code or parameters for a
|
|
limited time period. It should not be used for configuring persistent
|
|
behavior.
|
|
- The field trial must have an end date. The end date may be pushed back if
|
|
necessary, but should not be pushed back indefinitely.
|
|
- A field trial must be associated with a bug that
|
|
- reserves the field trial key,
|
|
- is open,
|
|
- is assigned to an owner, and
|
|
- has the end date specified.
|