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authorJosh Steadmon <steadmon@google.com>2024-08-22 14:57:45 -0700
committerJunio C Hamano <gitster@pobox.com>2024-08-22 15:02:31 -0700
commitcbe140754bc1eb4380ffe820de121e49357a9af8 (patch)
tree850e955f9173a3165f27d0db183ed4fd9b94551a /Documentation/technical
parent3a7362eb9fad0c4838f5cfaa95ed3c51a4c18d93 (diff)
downloadgit-cbe140754bc1eb4380ffe820de121e49357a9af8.tar.gz
trace2: implement trace2_printf() for event target
The trace2 event target does not have an implementation for trace2_printf(). While the event target is for structured events, and trace2_printf() is for unstructured, human-readable messages, it may still be useful to wrap these unstructured messages in a structured JSON object. Among other things, it may reduce confusion when manually debugging using event trace data. Add a simple implementation for the event target that wraps trace2_printf() messages in a minimal JSON object. Document this in Documentation/technical/api-trace2.txt, and bump the event format version since we're adding a new event type. Signed-off-by: Josh Steadmon <steadmon@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
Diffstat (limited to 'Documentation/technical')
-rw-r--r--Documentation/technical/api-trace2.txt17
1 files changed, 15 insertions, 2 deletions
diff --git a/Documentation/technical/api-trace2.txt b/Documentation/technical/api-trace2.txt
index de5fc25059..5817b18310 100644
--- a/Documentation/technical/api-trace2.txt
+++ b/Documentation/technical/api-trace2.txt
@@ -128,7 +128,7 @@ yields
------------
$ cat ~/log.event
-{"event":"version","sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.620713Z","file":"common-main.c","line":38,"evt":"3","exe":"2.20.1.155.g426c96fcdb"}
+{"event":"version","sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.620713Z","file":"common-main.c","line":38,"evt":"4","exe":"2.20.1.155.g426c96fcdb"}
{"event":"start","sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.621027Z","file":"common-main.c","line":39,"t_abs":0.001173,"argv":["git","version"]}
{"event":"cmd_name","sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.621122Z","file":"git.c","line":432,"name":"version","hierarchy":"version"}
{"event":"exit","sid":"20190408T191610.507018Z-H9b68c35f-P000059a8","thread":"main","time":"2019-01-16T17:28:42.621236Z","file":"git.c","line":662,"t_abs":0.001227,"code":0}
@@ -344,7 +344,7 @@ only present on the "start" and "atexit" events.
{
"event":"version",
...
- "evt":"3", # EVENT format version
+ "evt":"4", # EVENT format version
"exe":"2.20.1.155.g426c96fcdb" # git version
}
------------
@@ -835,6 +835,19 @@ The "value" field may be an integer or a string.
}
------------
+`"printf"`::
+ This event logs a human-readable message with no particular formatting
+ guidelines.
++
+------------
+{
+ "event":"printf",
+ ...
+ "t_abs":0.015905, # elapsed time in seconds
+ "msg":"Hello world" # optional
+}
+------------
+
== Example Trace2 API Usage