docs(readme): add error-handling to example code (segmentio#513)

huangfu · Sep 19, 2020 · 418f1fd · 418f1fd
1 parent 7bc2404
commit 418f1fd
Showing 1 changed file with 41 additions and 14 deletions.
diff --git a/README.md b/README.md
@@ -50,23 +50,34 @@ Here are some examples showing typical use of a connection object:
 topic := "my-topic"
 partition := 0
 
-conn, _ := kafka.DialLeader(context.Background(), "tcp", "localhost:9092", topic, partition)
+conn, err := kafka.DialLeader(context.Background(), "tcp", "localhost:9092", topic, partition)
+if err != nil {
+    log.Fatal("failed to dial leader:", err)
+}
 
 conn.SetWriteDeadline(time.Now().Add(10*time.Second))
-conn.WriteMessages(
+err := conn.WriteMessages(
     kafka.Message{Value: []byte("one!")},
     kafka.Message{Value: []byte("two!")},
     kafka.Message{Value: []byte("three!")},
 )
+if err != nil {
+    log.Fatal("failed to write messages:", err)
+}
 
-conn.Close()
+if err := conn.Close(); err != nil {
+    log.Fatal("failed to close writer:", err)
+}
 ```
 ```go
 // to consume messages
 topic := "my-topic"
 partition := 0
 
-conn, _ := kafka.DialLeader(context.Background(), "tcp", "localhost:9092", topic, partition)
+conn, err := kafka.DialLeader(context.Background(), "tcp", "localhost:9092", topic, partition)
+if err != nil {
+    log.Fatal("failed to dial leader:", err)
+}
 
 conn.SetReadDeadline(time.Now().Add(10*time.Second))
 batch := conn.ReadBatch(10e3, 1e6) // fetch 10KB min, 1MB max
@@ -80,8 +91,13 @@ for {
     fmt.Println(string(b))
 }
 
-batch.Close()
-conn.Close()
+if err := batch.Close(); err != nil {
+    log.Fatal("failed to close batch:", err)
+}
+
+if err := conn.Close(); err != nil {
+    log.Fatal("failed to close connection:", err)
+}
 ```
 
 Because it is low level, the `Conn` type turns out to be a great building block
@@ -115,7 +131,9 @@ for {
     fmt.Printf("message at offset %d: %s = %s\n", m.Offset, string(m.Key), string(m.Value))
 }
 
-r.Close()
+if err := r.Close(); err != nil {
+    log.Fatal("failed to close reader:", err)
+}
 ```
 
 ### Consumer Groups
@@ -143,7 +161,9 @@ for {
     fmt.Printf("message at topic/partition/offset %v/%v/%v: %s = %s\n", m.Topic, m.Partition, m.Offset, string(m.Key), string(m.Value))
 }
 
-r.Close()
+if err := r.Close(); err != nil {
+    log.Fatal("failed to close reader:", err)
+}
 ```
 
 There are a number of limitations when using consumer groups:
@@ -167,7 +187,9 @@ for {
         break
     }
     fmt.Printf("message at topic/partition/offset %v/%v/%v: %s = %s\n", m.Topic, m.Partition, m.Offset, string(m.Key), string(m.Value))
-    r.CommitMessages(ctx, m)
+    if err := r.CommitMessages(ctx, m); err != nil {
+        log.Fatal("failed to commit messages:", err)
+    }
 }
 ```
 
@@ -210,7 +232,7 @@ w := kafka.NewWriter(kafka.WriterConfig{
 	Balancer: &kafka.LeastBytes{},
 })
 
-w.WriteMessages(context.Background(),
+err := w.WriteMessages(context.Background(),
 	kafka.Message{
 		Key:   []byte("Key-A"),
 		Value: []byte("Hello World!"),
@@ -224,8 +246,13 @@ w.WriteMessages(context.Background(),
 		Value: []byte("Two!"),
 	},
 )
+if err != nil {
+    log.Fatal("failed to write messages:", err)
+}
 
-w.Close()
+if err := w.Close(); err != nil {
+    log.Fatal("failed to close writer:", err)
+}
 ```
 
 **Note:** Even though kafka.Message contain ```Topic``` and ```Partition``` fields, they **MUST NOT** be
@@ -286,9 +313,9 @@ w := kafka.NewWriter(kafka.WriterConfig{
 })
 ```
 
-The `Reader` will by determine if the consumed messages are compressed by 
-examining the message attributes.  However, the package(s) for all expected 
-codecs must be imported so that they get loaded correctly.  For example, if you 
+The `Reader` will by determine if the consumed messages are compressed by
+examining the message attributes.  However, the package(s) for all expected
+codecs must be imported so that they get loaded correctly.  For example, if you
 are going to be receiving messages compressed with Snappy, add the following
 import: