producer: Adds a Ping method in order to validate an nsqd connection

Signed-off-by: dcarney <dcarney@gmail.com>

producer.go

@@ -91,6 +91,23 @@ func NewProducer(addr string, config *Config) (*Producer, error) {
  return p, nil
 }
 
+// Ping causes the Producer to connect to it's configured nsqd (if not already
+// connected) and send a `Nop` command, returning any error that might occur.
+//
+// This method can be used to verify that a newly-created Producer instance is
+// configured correctly, rather than relying on the lazy "connect on Publish"
+// behavior of a Producer.
+func (w *Producer) Ping() error {
+ if atomic.LoadInt32(&w.state) != StateConnected {
+ err := w.connect()
+ if err != nil {
+ return err
+ }
+ }
+
+ return w.conn.WriteCommand(Nop())
+}
+
 // SetLogger assigns the logger to use as well as a level
 //
 // The logger parameter is an interface that requires the following

producer_test.go

@@ -3,6 +3,9 @@ package nsq
 import (
  "bytes"
  "errors"
+ "io/ioutil"
+ "log"
+ "os"
  "runtime"
  "strconv"
  "sync"
@@ -53,6 +56,28 @@ func TestProducerConnection(t *testing.T) {
  }
 }
 
+func TestProducerPing(t *testing.T) {
+ log.SetOutput(ioutil.Discard)
+ defer log.SetOutput(os.Stdout)
+
+ config := NewConfig()
+ w, _ := NewProducer("127.0.0.1:4150", config)
+ w.SetLogger(nullLogger, LogLevelInfo)
+
+ err := w.Ping()
+
+ if err != nil {
+ t.Fatalf("should connect on ping")
+ }
+
+ w.Stop()
+
+ err = w.Ping()
+ if err != ErrStopped {
+ t.Fatalf("should not be able to ping after Stop()")
+ }
+}
+
 func TestProducerPublish(t *testing.T) {
  topicName := "publish" + strconv.Itoa(int(time.Now().Unix()))
  msgCount := 10