[PATCH 1/2] perf stat: Fix JSON metric printout for multiple metrics per line

[Michael Petlan <mpetlan@redhat.com>]

JSON printing engine used to always print metric (even when there should
be none and other engines (std, csv) would not print it) and the metric
used to always close the line by printing a closing curly bracket.

This caused invalid JSON output being generated for top-down metrics,
when multiple metrics are printed on a single line, so the broken output
might have looked like:

  ... "metric-value" : 15.564203, "metric-unit" : \
  "Memory Bound"}"metric-value" : 14.007787, "metric-unit" : "Core Bound"}

To fix it, print always the separating comma BEFORE the key:value pairs
and close the line outside of the JSON metric printing routine.

Fixes: df936cadfb58 ("perf stat: Add JSON output option")

Signed-off-by: Michael Petlan <mpetlan@redhat.com>
---
 tools/perf/util/stat-display.c | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index 8bd8b0142630..8f80f6b566d0 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -86,7 +86,7 @@ static void print_running_json(struct perf_stat_config *config, u64 run, u64 ena
 
 	if (run != ena)
 		enabled_percent = 100 * run / ena;
-	fprintf(config->output, "\"event-runtime\" : %" PRIu64 ", \"pcnt-running\" : %.2f, ",
+	fprintf(config->output, ", \"event-runtime\" : %" PRIu64 ", \"pcnt-running\" : %.2f",
 		run, enabled_percent);
 }
 
@@ -121,7 +121,7 @@ static void print_noise_pct_csv(struct perf_stat_config *config,
 static void print_noise_pct_json(struct perf_stat_config *config,
 				 double pct)
 {
-	fprintf(config->output, "\"variance\" : %.2f, ", pct);
+	fprintf(config->output, ", \"variance\" : %.2f", pct);
 }
 
 static void print_noise_pct(struct perf_stat_config *config,
@@ -165,7 +165,7 @@ static void print_cgroup_csv(struct perf_stat_config *config, const char *cgrp_n
 
 static void print_cgroup_json(struct perf_stat_config *config, const char *cgrp_name)
 {
-	fprintf(config->output, "\"cgroup\" : \"%s\", ", cgrp_name);
+	fprintf(config->output, ", \"cgroup\" : \"%s\"", cgrp_name);
 }
 
 static void print_cgroup(struct perf_stat_config *config, struct cgroup *cgrp)
@@ -431,10 +431,11 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
 	struct outstate *os = ctx;
 	FILE *out = os->fh;
 
-	fprintf(out, "\"metric-value\" : %f, ", val);
-	fprintf(out, "\"metric-unit\" : \"%s\"", unit);
-	if (!config->metric_only)
-		fprintf(out, "}");
+	if (unit == NULL || fmt == NULL)
+		return;
+
+	fprintf(out, ", \"metric-value\" : %f", val);
+	fprintf(out, ", \"metric-unit\" : \"%s\"", unit);
 }
 
 static void new_line_json(struct perf_stat_config *config, void *ctx)
@@ -623,14 +624,14 @@ static void print_counter_value_json(struct perf_stat_config *config,
 	const char *bad_count = evsel->supported ? CNTR_NOT_COUNTED : CNTR_NOT_SUPPORTED;
 
 	if (ok)
-		fprintf(output, "\"counter-value\" : \"%f\", ", avg);
+		fprintf(output, "\"counter-value\" : \"%f\"", avg);
 	else
-		fprintf(output, "\"counter-value\" : \"%s\", ", bad_count);
+		fprintf(output, "\"counter-value\" : \"%s\"", bad_count);
 
 	if (evsel->unit)
-		fprintf(output, "\"unit\" : \"%s\", ", evsel->unit);
+		fprintf(output, ", \"unit\" : \"%s\"", evsel->unit);
 
-	fprintf(output, "\"event\" : \"%s\", ", evsel__name(evsel));
+	fprintf(output, ", \"event\" : \"%s\"", evsel__name(evsel));
 }
 
 static void print_counter_value(struct perf_stat_config *config,
@@ -835,8 +836,11 @@ static void print_counter_aggrdata(struct perf_stat_config *config,
 
 	printout(config, os, uval, run, ena, avg, s);
 
-	if (!metric_only)
+	if (!metric_only) {
+		if (config->json_output)
+			fputc('}', output);
 		fputc('\n', output);
+	}
 }
 
 static void print_metric_begin(struct perf_stat_config *config,
-- 
2.18.4