[PATCH v2 2/3] trace2: avoid emitting 'def_param' set more than once

["Jeff Hostetler via GitGitGadget" <gitgitgadget@gmail.com>]

From: Jeff Hostetler <jeffhostetler@github.com>

During nested alias expansion it is possible for
"trace2_cmd_list_config()" and "trace2_cmd_list_env_vars()"
to be called more than once.  This causes a full set of
'def_param' events to be emitted each time.  Let's avoid
that.

Add code to those two functions to only emit them once.

Signed-off-by: Jeff Hostetler <jeffhostetler@github.com>
---
 t/t0211-trace2-perf.sh |  2 +-
 trace2.c               | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/t/t0211-trace2-perf.sh b/t/t0211-trace2-perf.sh
index 588c5bad033..7b353195396 100755
--- a/t/t0211-trace2-perf.sh
+++ b/t/t0211-trace2-perf.sh
@@ -470,7 +470,7 @@ test_expect_success 'expect def_params during shell alias expansion' '
 	grep "d1|main|def_param|.*|ENV_PROP_FOO:blue" actual
 '
 
-test_expect_failure 'expect def_params during nested git alias expansion' '
+test_expect_success 'expect def_params during nested git alias expansion' '
 	test_when_finished "rm prop.perf actual" &&
 
 	test_config_global "trace2.configParams" "cfg.prop.*" &&
diff --git a/trace2.c b/trace2.c
index f1e268bd159..facce641ef3 100644
--- a/trace2.c
+++ b/trace2.c
@@ -464,17 +464,29 @@ void trace2_cmd_alias_fl(const char *file, int line, const char *alias,
 
 void trace2_cmd_list_config_fl(const char *file, int line)
 {
+	static int emitted = 0;
+
 	if (!trace2_enabled)
 		return;
 
+	if (emitted)
+		return;
+	emitted = 1;
+
 	tr2_cfg_list_config_fl(file, line);
 }
 
 void trace2_cmd_list_env_vars_fl(const char *file, int line)
 {
+	static int emitted = 0;
+
 	if (!trace2_enabled)
 		return;
 
+	if (emitted)
+		return;
+	emitted = 1;
+
 	tr2_list_env_vars_fl(file, line);
 }
 
-- 
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