docs: Add example

Signed-off-by: Bo-Yi Wu <[email protected]>

Author: appleboy

README.md

@@ -31,3 +31,81 @@ nsqadmin --lookupd-http-address localhost:4161
 ```sh
 go test -v ./...
 ```
+
+## Example
+
+```go
+package main
+
+import (
+  "context"
+  "encoding/json"
+  "fmt"
+  "log"
+  "time"
+
+  "github.com/golang-queue/nsq"
+  "github.com/golang-queue/queue"
+)
+
+type job struct {
+  Message string
+}
+
+func (j *job) Bytes() []byte {
+  b, err := json.Marshal(j)
+  if err != nil {
+    panic(err)
+  }
+  return b
+}
+
+func main() {
+  taskN := 100
+  rets := make(chan string, taskN)
+
+  // define the worker
+  w := nsq.NewWorker(
+    nsq.WithAddr("127.0.0.1:4150"),
+    nsq.WithTopic("example"),
+    nsq.WithChannel("foobar"),
+    // concurrent job number
+    nsq.WithMaxInFlight(10),
+    nsq.WithRunFunc(func(ctx context.Context, m queue.QueuedMessage) error {
+      var v *job
+      if err := json.Unmarshal(m.Bytes(), &v); err != nil {
+        return err
+      }
+      rets <- v.Message
+      return nil
+    }),
+  )
+
+  // define the queue
+  q := queue.NewPool(
+    10,
+    queue.WithWorker(w),
+  )
+  defer q.Release()
+
+  // start the five worker
+  q.Start()
+
+  // assign tasks in queue
+  for i := 0; i < taskN; i++ {
+    go func(i int) {
+      if err := q.Queue(&job{
+        Message: fmt.Sprintf("handle the job: %d", i+1),
+      }); err != nil {
+        log.Fatal(err)
+      }
+    }(i)
+  }
+
+  // wait until all tasks done
+  for i := 0; i < taskN; i++ {
+    fmt.Println("message:", <-rets)
+    time.Sleep(50 * time.Millisecond)
+  }
+}
+```

_example/main.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"log"
 	"time"
 
 	"github.com/golang-queue/nsq"
@@ -34,13 +35,10 @@ func main() {
 		// concurrent job number
 		nsq.WithMaxInFlight(10),
 		nsq.WithRunFunc(func(ctx context.Context, m queue.QueuedMessage) error {
-			v, ok := m.(*job)
-			if !ok {
-				if err := json.Unmarshal(m.Bytes(), &v); err != nil {
-					return err
-				}
+			var v *job
+			if err := json.Unmarshal(m.Bytes(), &v); err != nil {
+				return err
 			}
-
 			rets <- v.Message
 			return nil
 		}),
@@ -59,9 +57,11 @@ func main() {
 	// assign tasks in queue
 	for i := 0; i < taskN; i++ {
 		go func(i int) {
-			q.Queue(&job{
+			if err := q.Queue(&job{
 				Message: fmt.Sprintf("handle the job: %d", i+1),
-			})
+			}); err != nil {
+				log.Fatal(err)
+			}
 		}(i)
 	}