feat: add max cmd bytes for otel hook

extra/redisotel/config.go

@@ -19,7 +19,8 @@ type config struct {
 	tp     trace.TracerProvider
 	tracer trace.Tracer
 
-	dbStmtEnabled bool
+	dbStmtEnabled   bool
+	maxCommandBytes int
 
 	// Metrics options.
 
@@ -54,9 +55,10 @@ func newConfig(opts ...baseOption) *config {
 		dbSystem: "redis",
 		attrs:    []attribute.KeyValue{},
 
-		tp:            otel.GetTracerProvider(),
-		mp:            otel.GetMeterProvider(),
-		dbStmtEnabled: true,
+		tp:              otel.GetTracerProvider(),
+		mp:              otel.GetMeterProvider(),
+		dbStmtEnabled:   true,
+		maxCommandBytes: 0,
 	}
 
 	for _, opt := range opts {
@@ -113,6 +115,14 @@ func WithDBStatement(on bool) TracingOption {
 	})
 }
 
+// WithMaxCommandBytes limit the bytes of raw redis commands.
+// Default is 0, don't limit.
+func WithMaxCommandBytes(size int) TracingOption {
+	return tracingOption(func(conf *config) {
+		conf.maxCommandBytes = size
+	})
+}
+
 //------------------------------------------------------------------------------
 
 type MetricsOption interface {

extra/redisotel/redisotel_test.go

@@ -2,6 +2,7 @@ package redisotel
 
 import (
 	"context"
+	"strings"
 	"testing"
 
 	semconv "go.opentelemetry.io/otel/semconv/v1.7.0"
@@ -59,3 +60,21 @@ func TestWithDBStatement(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestMaxString(t *testing.T) {
+	src := strings.Repeat("a", 100)
+	dst := maxString(src, 50)
+	if dst != src[:50] {
+		t.Fatal("failed to maxstring")
+	}
+
+	dst = maxString(src, 200)
+	if dst != src {
+		t.Fatal("failed to maxstring")
+	}
+
+	dst = maxString(src, 0)
+	if dst != src {
+		t.Fatal("failed to maxstring")
+	}
+}

extra/redisotel/tracing.go

@@ -27,6 +27,7 @@ func InstrumentTracing(rdb redis.UniversalClient, opts ...TracingOption) error {
 		connString := formatDBConnString(opt.Network, opt.Addr)
 		rdb.AddHook(newTracingHook(connString, opts...))
 		return nil
+
 	case *redis.ClusterClient:
 		rdb.AddHook(newTracingHook("", opts...))
 
@@ -120,6 +121,9 @@ func (th *tracingHook) ProcessHook(hook redis.ProcessHook) redis.ProcessHook {
 
 		if th.conf.dbStmtEnabled {
 			cmdString := rediscmd.CmdString(cmd)
+			if th.conf.maxCommandBytes > 0 {
+				cmdString = maxString(cmdString, th.conf.maxCommandBytes)
+			}
 			attrs = append(attrs, semconv.DBStatementKey.String(cmdString))
 		}
 
@@ -157,6 +161,9 @@ func (th *tracingHook) ProcessPipelineHook(
 
 		summary, cmdsString := rediscmd.CmdsString(cmds)
 		if th.conf.dbStmtEnabled {
+			if th.conf.maxCommandBytes > 0 {
+				cmdsString = maxString(cmdsString, th.conf.maxCommandBytes)
+			}
 			attrs = append(attrs, semconv.DBStatementKey.String(cmdsString))
 		}
 
@@ -213,3 +220,14 @@ func funcFileLine(pkg string) (string, string, int) {
 
 	return fn, file, line
 }
+
+func maxString(s string, length int) string {
+	if length <= 0 { // no define or no limit
+		return s
+	}
+
+	if len(s) > length {
+		return s[:length]
+	}
+	return s
+}