[PATCH v2 2/2] tr2: shows scope unconditionally in addition to key-value pair

[Teng Long <dyroneteng@gmail.com>]

From: Teng Long <dyroneteng@gmail.com>

When we specify GIT_TRACE2_CONFIG_PARAMS or trace2.configparams,
trace2 will prints "interesting" config values to log. Sometimes,
when a config set in multiple scope files, the following output
looks like (the irrelevant fields are omitted here as "..."):

...| def_param    |  ...  | core.multipackindex:false
...| def_param    |  ...  | core.multipackindex:false
...| def_param    |  ...  | core.multipackindex:false

As the log shows, even each config in different scope is dumped, but
we don't know which scope it comes from. Therefore, it's better to
add the scope names as well to make them be more recognizable. For
example, when execute:

    $ GIT_TRACE2_PERF=1 \
    > GIT_TRACE2_CONFIG_PARAMS=core.multipackIndex \
    > git rev-list --test-bitmap HEAD"

The following is the ouput (the irrelevant fields are omitted here
as "..."):

Format normal:
... git.c:461 ... def_param scope:system core.multipackindex=false
... git.c:461 ... def_param scope:global core.multipackindex=false
... git.c:461 ... def_param scope:local core.multipackindex=false

Format perf:

... | def_param    | ... | scope:system | core.multipackindex:false
... | def_param    | ... | scope:global | core.multipackindex:false
... | def_param    | ... | scope:local  | core.multipackindex:false

Format event:

{"event":"def_param", ... ,"scope":"system","param":"core.multipackindex","value":"false"}
{"event":"def_param", ... ,"scope":"global","param":"core.multipackindex","value":"false"}
{"event":"def_param", ... ,"scope":"local","param":"core.multipackindex","value":"false"}

Signed-off-by: Teng Long <dyroneteng@gmail.com>
---
 Documentation/technical/api-trace2.txt | 17 +++++++++++++----
 trace2/tr2_tgt_event.c                 |  3 +++
 trace2/tr2_tgt_normal.c                |  5 ++++-
 trace2/tr2_tgt_perf.c                  |  9 +++++++--
 4 files changed, 27 insertions(+), 7 deletions(-)

diff --git a/Documentation/technical/api-trace2.txt b/Documentation/technical/api-trace2.txt
index 38d0878d85..2afa28bb5a 100644
--- a/Documentation/technical/api-trace2.txt
+++ b/Documentation/technical/api-trace2.txt
@@ -717,6 +717,7 @@ The "exec_id" field is a command-unique id and is only useful if the
 {
 	"event":"def_param",
 	...
+	"scope":"global",
 	"param":"core.abbrev",
 	"value":"7"
 }
@@ -1216,7 +1217,13 @@ We can optionally emit configuration events, see
 it.
 +
 ----------------
-$ git config color.ui auto
+$ git config --system color.ui never
+$ git config --global color.ui always
+$ git config --local color.ui auto
+$ git config --list --show-scope | grep 'color.ui'
+system  color.ui=never
+global  color.ui=always
+local   color.ui=auto
 ----------------
 +
 Then, mark the config `color.ui` as "interesting" config with
@@ -1232,11 +1239,13 @@ $ cat ~/log.perf
 d0 | main                     | version      |     |           |           |              | ...
 d0 | main                     | start        |     |  0.001642 |           |              | /usr/local/bin/git version
 d0 | main                     | cmd_name     |     |           |           |              | version (version)
-d0 | main                     | def_param    |     |           |           |              | color.ui:auto
+d0 | main                     | def_param    |     |           |           | scope:system | color.ui:never
+d0 | main                     | def_param    |     |           |           | scope:global | color.ui:always
+d0 | main                     | def_param    |     |           |           | scope:local  | color.ui:auto
 d0 | main                     | data         | r0  |  0.002100 |  0.002100 | fsync        | fsync/writeout-only:0
 d0 | main                     | data         | r0  |  0.002126 |  0.002126 | fsync        | fsync/hardware-flush:0
-d0 | main                     | exit         |     |  0.002142 |           |              | code:0
-d0 | main                     | atexit       |     |  0.002161 |           |              | code:0
+d0 | main                     | exit         |     |  0.000470 |           |              | code:0
+d0 | main                     | atexit       |     |  0.000477 |           |              | code:0
 ----------------
 == Future Work
 
diff --git a/trace2/tr2_tgt_event.c b/trace2/tr2_tgt_event.c
index c5c8cfbbaa..37a3163be1 100644
--- a/trace2/tr2_tgt_event.c
+++ b/trace2/tr2_tgt_event.c
@@ -479,9 +479,12 @@ static void fn_param_fl(const char *file, int line, const char *param,
 {
 	const char *event_name = "def_param";
 	struct json_writer jw = JSON_WRITER_INIT;
+	enum config_scope scope = current_config_scope();
+	const char *scope_name = config_scope_name(scope);
 
 	jw_object_begin(&jw, 0);
 	event_fmt_prepare(event_name, file, line, NULL, &jw);
+	jw_object_string(&jw, "scope", scope_name);
 	jw_object_string(&jw, "param", param);
 	jw_object_string(&jw, "value", value);
 	jw_end(&jw);
diff --git a/trace2/tr2_tgt_normal.c b/trace2/tr2_tgt_normal.c
index c42fbade7f..69f8033077 100644
--- a/trace2/tr2_tgt_normal.c
+++ b/trace2/tr2_tgt_normal.c
@@ -298,8 +298,11 @@ static void fn_param_fl(const char *file, int line, const char *param,
 			const char *value)
 {
 	struct strbuf buf_payload = STRBUF_INIT;
+	enum config_scope scope = current_config_scope();
+	const char *scope_name = config_scope_name(scope);
 
-	strbuf_addf(&buf_payload, "def_param %s=%s", param, value);
+	strbuf_addf(&buf_payload, "def_param scope:%s %s=%s", scope_name, param,
+		    value);
 	normal_io_write_fl(file, line, &buf_payload);
 	strbuf_release(&buf_payload);
 }
diff --git a/trace2/tr2_tgt_perf.c b/trace2/tr2_tgt_perf.c
index a1eff8bea3..8cb792488c 100644
--- a/trace2/tr2_tgt_perf.c
+++ b/trace2/tr2_tgt_perf.c
@@ -441,12 +441,17 @@ static void fn_param_fl(const char *file, int line, const char *param,
 {
 	const char *event_name = "def_param";
 	struct strbuf buf_payload = STRBUF_INIT;
+	struct strbuf scope_payload = STRBUF_INIT;
+	enum config_scope scope = current_config_scope();
+	const char *scope_name = config_scope_name(scope);
 
 	strbuf_addf(&buf_payload, "%s:%s", param, value);
+	strbuf_addf(&scope_payload, "%s:%s", "scope", scope_name);
 
-	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL, NULL,
-			 &buf_payload);
+	perf_io_write_fl(file, line, event_name, NULL, NULL, NULL,
+			 scope_payload.buf, &buf_payload);
 	strbuf_release(&buf_payload);
+	strbuf_release(&scope_payload);
 }
 
 static void fn_repo_fl(const char *file, int line,
-- 
2.37.1.1.g8cbb44ffc4.dirty