From fc5be74fe9f371d037089f793df724c4fef9027c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Catt=C4=AB=20Cr=C5=ABd=C4=93l=C4=93s?=
 <17695588+wzy9607@users.noreply.github.com>
Date: Sun, 15 Sep 2024 18:26:16 +0800
Subject: [PATCH] fix(redisotel): fix buggy append in reportPoolStats

The current append twice to `conf.attrs` approach in `reportPoolStats` may result in unexpected idleAttrs,
due to `append` [can mutate](https://github.com/golang/go/issues/29115#issuecomment-444669036) the underlying array of the original slice,
as demonstrated at <https://go.dev/play/p/jwRMofH91eQ?v=goprev>.

Also, I replaced `metric.WithAttributes` in `reportPoolStats` with `metric.WithAttributeSet`,
since `WithAttributes` is just `WithAttributeSet` with some extra works that are not needed here,
see <https://pkg.go.dev/go.opentelemetry.io/otel/metric@v1.22.0#WithAttributes>.
---
 extra/redisotel/metrics.go | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/extra/redisotel/metrics.go b/extra/redisotel/metrics.go
index 915838f3..2778c7bc 100644
--- a/extra/redisotel/metrics.go
+++ b/extra/redisotel/metrics.go
@@ -83,9 +83,9 @@ func InstrumentMetrics(rdb redis.UniversalClient, opts ...MetricsOption) error {
 }
 
 func reportPoolStats(rdb *redis.Client, conf *config) error {
-	labels := conf.attrs
-	idleAttrs := append(labels, attribute.String("state", "idle"))
-	usedAttrs := append(labels, attribute.String("state", "used"))
+	poolAttrs := attribute.NewSet(conf.attrs...)
+	idleAttrs := attribute.NewSet(append(poolAttrs.ToSlice(), attribute.String("state", "idle"))...)
+	usedAttrs := attribute.NewSet(append(poolAttrs.ToSlice(), attribute.String("state", "used"))...)
 
 	idleMax, err := conf.meter.Int64ObservableUpDownCounter(
 		"db.client.connections.idle.max",
@@ -132,14 +132,14 @@ func reportPoolStats(rdb *redis.Client, conf *config) error {
 		func(ctx context.Context, o metric.Observer) error {
 			stats := rdb.PoolStats()
 
-			o.ObserveInt64(idleMax, int64(redisConf.MaxIdleConns), metric.WithAttributes(labels...))
-			o.ObserveInt64(idleMin, int64(redisConf.MinIdleConns), metric.WithAttributes(labels...))
-			o.ObserveInt64(connsMax, int64(redisConf.PoolSize), metric.WithAttributes(labels...))
+			o.ObserveInt64(idleMax, int64(redisConf.MaxIdleConns), metric.WithAttributeSet(poolAttrs))
+			o.ObserveInt64(idleMin, int64(redisConf.MinIdleConns), metric.WithAttributeSet(poolAttrs))
+			o.ObserveInt64(connsMax, int64(redisConf.PoolSize), metric.WithAttributeSet(poolAttrs))
 
-			o.ObserveInt64(usage, int64(stats.IdleConns), metric.WithAttributes(idleAttrs...))
-			o.ObserveInt64(usage, int64(stats.TotalConns-stats.IdleConns), metric.WithAttributes(usedAttrs...))
+			o.ObserveInt64(usage, int64(stats.IdleConns), metric.WithAttributeSet(idleAttrs))
+			o.ObserveInt64(usage, int64(stats.TotalConns-stats.IdleConns), metric.WithAttributeSet(usedAttrs))
 
-			o.ObserveInt64(timeouts, int64(stats.Timeouts), metric.WithAttributes(labels...))
+			o.ObserveInt64(timeouts, int64(stats.Timeouts), metric.WithAttributeSet(poolAttrs))
 			return nil
 		},
 		idleMax,