From 11c4d6f5566cb5cec8f89f5c4eaaf8d87851a2f3 Mon Sep 17 00:00:00 2001
From: Vladimir Mihailenco <vladimir.webdev@gmail.com>
Date: Wed, 8 Sep 2021 15:54:10 +0300
Subject: [PATCH] chore: cleanup OpenTelemetry example

---
 example/otel/README.md                      | 21 ++++++---
 example/otel/docker-compose.yml             |  3 +-
 example/otel/{example-client.go => main.go} | 49 +++++++++++++--------
 tx.go                                       |  3 +-
 4 files changed, 49 insertions(+), 27 deletions(-)
 rename example/otel/{example-client.go => main.go} (54%)

diff --git a/example/otel/README.md b/example/otel/README.md
index 60d4d12..40db8ac 100644
--- a/example/otel/README.md
+++ b/example/otel/README.md
@@ -1,9 +1,16 @@
-### OpenTelemetry Example 
-Prints spans and metrics to the console.
-#### To Run:
-- `docker-compose up -d`
-- `go run .`
+# Example for go-redis OpenTelemetry instrumentation
 
-When you're finished, be sure to run `docker-compose down` to shutdown
-the redis server.
+This example requires running Redis Server. You can start Redis Server using Docker:
 
+```shell
+docker-compose up -d
+```
+
+To run this example:
+
+```shell
+go run .
+```
+
+See [Monitoring performance and errors](https://redis.uptrace.dev/guide/tracing.html) for more
+details.
diff --git a/example/otel/docker-compose.yml b/example/otel/docker-compose.yml
index c2d7f1d..ff8f066 100644
--- a/example/otel/docker-compose.yml
+++ b/example/otel/docker-compose.yml
@@ -1,8 +1,9 @@
 version: '3'
+
 services:
   redis-server:
     image: redis
     ports:
-      - "6379:6379"
+      - '6379:6379'
   redis-cli:
     image: redis
diff --git a/example/otel/example-client.go b/example/otel/main.go
similarity index 54%
rename from example/otel/example-client.go
rename to example/otel/main.go
index 546d6c8..9bb272e 100644
--- a/example/otel/example-client.go
+++ b/example/otel/main.go
@@ -2,35 +2,45 @@ package main
 
 import (
 	"context"
-	"log"
 	"sync"
-	"time"
 
 	"github.com/go-redis/redis/extra/redisotel/v8"
 	"github.com/go-redis/redis/v8"
 	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/codes"
 	"go.opentelemetry.io/otel/exporters/stdout/stdouttrace"
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
 )
 
+var tracer = otel.Tracer("redisexample")
+
 func main() {
 	ctx := context.Background()
 
-	stop := runExporter(ctx)
-	defer stop(ctx)
+	stop := configureOpentelemetry(ctx)
+	defer stop()
 
 	rdb := redis.NewClient(&redis.Options{
 		Addr: ":6379",
 	})
-
 	rdb.AddHook(redisotel.TracingHook{})
 
-	tracer := otel.Tracer("Example tracer")
-	ctx, span := tracer.Start(ctx, "start-test-span")
+	ctx, span := tracer.Start(ctx, "handleRequest")
+	defer span.End()
 
-	rdb.Set(ctx, "First value", "value_1", 0)
+	if err := handleRequest(ctx); err != nil {
+		span.RecordError(err)
+		span.SetStatus(codes.Error, err.Error())
+	}
+}
 
-	rdb.Set(ctx, "Second value", "value_2", 0)
+func handleRequest(ctx context.Context) error {
+	if err := rdb.Set(ctx, "First value", "value_1", 0).Err(); err != nil {
+		return err
+	}
+	if err := rdb.Set(ctx, "Second value", "value_2", 0).Err(); err != nil {
+		return err
+	}
 
 	var group sync.WaitGroup
 
@@ -40,27 +50,30 @@ func main() {
 			defer group.Done()
 			val := rdb.Get(ctx, "Second value").Val()
 			if val != "value_2" {
-				log.Fatalf("val was not set. expected: %s but got: %s", "value_2", val)
+				panic(err)
 			}
 		}()
 	}
+
 	group.Wait()
 
-	rdb.Del(ctx, "First value")
-	rdb.Del(ctx, "Second value")
+	if err := rdb.Del(ctx, "First value").Err(); err != nil {
+		return err
+	}
+	if err := rdb.Del(ctx, "Second value").Err(); err != nil {
+		return err
+	}
 
-	// Wait some time to allow spans to export
-	<-time.After(5 * time.Second)
-	span.End()
+	return nil
 }
 
-func runExporter(ctx context.Context) func(context.Context) {
+func configureOpentelemetry(ctx context.Context) func() {
 	provider := sdktrace.NewTracerProvider()
 	otel.SetTracerProvider(provider)
 
 	exp, err := stdouttrace.New(stdouttrace.WithPrettyPrint())
 	if err != nil {
-		log.Fatal(err)
+		panic(err)
 	}
 
 	bsp := sdktrace.NewBatchSpanProcessor(exp)
@@ -68,7 +81,7 @@ func runExporter(ctx context.Context) func(context.Context) {
 
 	return func(ctx context.Context) {
 		if err := provider.Shutdown(ctx); err != nil {
-			log.Printf("Shutdown failed: %s", err)
+			panic(err)
 		}
 	}
 }
diff --git a/tx.go b/tx.go
index 08d381a..8c9d872 100644
--- a/tx.go
+++ b/tx.go
@@ -13,7 +13,8 @@ const TxFailedErr = proto.RedisError("redis: transaction failed")
 // Tx implements Redis transactions as described in
 // http://redis.io/topics/transactions. It's NOT safe for concurrent use
 // by multiple goroutines, because Exec resets list of watched keys.
-// If you don't need WATCH it is better to use Pipeline.
+//
+// If you don't need WATCH, use Pipeline instead.
 type Tx struct {
 	baseClient
 	cmdable