trace2: add variable description to git.txt

Documentation/technical/api-trace2.txt contains the full details of the trace2 API and the GIT_TR2* environment variables. However, most environment variables are included in Documentation/git.txt, including the GIT_TRACE* variables. Add a brief description of the GIT_TR2* variables with links to the full technical details. The biggest difference from the original variables is that we can specify a Unix Domain Socket. Mention this difference, but leave the details to the technical documents. Reported-by: Szeder Gábor <szeder.dev@gmail.com> Signed-off-by: Derrick Stolee <dstolee@microsoft.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Derrick Stolee committed May 10, 2019 at 12:44 UTC 04b7e86e4854fecc8cca1d3c08af5cfe771e9091
1 file changed +21
Documentation/git.txt
+21
@@ -660,6 +660,27 @@ of clones and fetches.
660 When a curl trace is enabled (see `GIT_TRACE_CURL` above), do not dump
661 data (that is, only dump info lines and headers).
662
663 +`GIT_TR2`::
664 + Enables more detailed trace messages from the "trace2" library.
665 + Output from `GIT_TR2` is a simple text-based format for human
666 + readability.
667 ++
668 +The `GIT_TR2` variables can take many values. Any value available to
669 +the `GIT_TRACE` variables is also available to `GIT_TR2`. The `GIT_TR2`
670 +variables can also specify a Unix Domain Socket. See
671 +link:technical/api-trace2.html[Trace2 documentation] for full details.
672 +
673 +`GIT_TR2_EVENT`::
674 + This setting writes a JSON-based format that is suited for machine
675 + interpretation. See link:technical/api-trace2.html[Trace2 documentation]
676 + for full details.
677 +
678 +`GIT_TR2_PERF`::
679 + In addition to the text-based messages available in `GIT_TR2`, this
680 + setting writes a column-based format for understanding nesting
681 + regions. See link:technical/api-trace2.html[Trace2 documentation]
682 + for full details.
683 +
684 `GIT_REDACT_COOKIES`::
685 This can be set to a comma-separated list of strings. When a curl trace
686 is enabled (see `GIT_TRACE_CURL` above), whenever a "Cookies:" header