Preallocate slice length instead of append

Author: urdarinda

extra/redisotel/metrics.go

@@ -214,8 +214,10 @@ func (mh *metricsHook) ProcessHook(hook redis.ProcessHook) redis.ProcessHook {
 
 		dur := time.Since(start)
 
-		attrs := make([]attribute.KeyValue, 0, len(mh.attrs)+2)
-		attrs = append(attrs, mh.attrsFunc(ctx)...)
+		customAttrs := mh.attrsFunc(ctx)
+		
+		attrs := make([]attribute.KeyValue, 0, len(mh.attrs) + len(customAttrs) + 2)
+		attrs = append(attrs, customAttrs...)
 		attrs = append(attrs, mh.attrs...)
 		attrs = append(attrs, attribute.String("type", "command"))
 		attrs = append(attrs, statusAttr(err))
@@ -236,8 +238,10 @@ func (mh *metricsHook) ProcessPipelineHook(
 
 		dur := time.Since(start)
 
-		attrs := make([]attribute.KeyValue, 0, len(mh.attrs)+2)
-		attrs = append(attrs, mh.attrsFunc(ctx)...)
+		customAttrs := mh.attrsFunc(ctx)
+
+		attrs := make([]attribute.KeyValue, 0, len(mh.attrs) + len(customAttrs) + 2)
+		attrs = append(attrs, customAttrs...)
 		attrs = append(attrs, mh.attrs...)
 		attrs = append(attrs, attribute.String("type", "pipeline"))
 		attrs = append(attrs, statusAttr(err))

extra/redisotel/tracing.go

@@ -103,7 +103,10 @@ func (th *tracingHook) ProcessHook(hook redis.ProcessHook) redis.ProcessHook {
 	return func(ctx context.Context, cmd redis.Cmder) error {
 		fn, file, line := funcFileLine("github.com/redis/go-redis")
 
-		attrs := make([]attribute.KeyValue, 0, 8)
+
+		customAttrs := th.conf.attrsFunc(ctx)
+
+		attrs := make([]attribute.KeyValue, 0, len(customAttrs) + 8)
 		attrs = append(attrs,
 			semconv.CodeFunction(fn),
 			semconv.CodeFilepath(file),
@@ -116,7 +119,7 @@ func (th *tracingHook) ProcessHook(hook redis.ProcessHook) redis.ProcessHook {
 		}
 
 		opts := th.spanOpts
-		opts = append(opts, trace.WithAttributes(th.conf.attrsFunc(ctx)...))
+		opts = append(opts, trace.WithAttributes(customAttrs...))
 		opts = append(opts, trace.WithAttributes(attrs...))
 
 		ctx, span := th.conf.tracer.Start(ctx, cmd.FullName(), opts...)
@@ -136,7 +139,9 @@ func (th *tracingHook) ProcessPipelineHook(
 	return func(ctx context.Context, cmds []redis.Cmder) error {
 		fn, file, line := funcFileLine("github.com/redis/go-redis")
 
-		attrs := make([]attribute.KeyValue, 0, 8)
+		customAttrs := th.conf.attrsFunc(ctx)
+		
+		attrs := make([]attribute.KeyValue, 0, len(customAttrs) + 8)
 		attrs = append(attrs,
 			semconv.CodeFunction(fn),
 			semconv.CodeFilepath(file),
@@ -150,7 +155,7 @@ func (th *tracingHook) ProcessPipelineHook(
 		}
 
 		opts := th.spanOpts
-		opts = append(opts, trace.WithAttributes(th.conf.attrsFunc(ctx)...))
+		opts = append(opts, trace.WithAttributes(customAttrs...))
 		opts = append(opts, trace.WithAttributes(attrs...))
 
 		ctx, span := th.conf.tracer.Start(ctx, "redis.pipeline "+summary, opts...)