Add grpc check example. (#306)

* Add grpc check example.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* add missing package.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

README.md

@@ -743,11 +743,11 @@ The following example code to send single notification in Go.
 package main
 
 import (
+	"context"
 	"log"
 
 	"github.com/appleboy/gorush/rpc/proto"
 
-	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
 
@@ -802,6 +802,47 @@ function main() {
 main();
 ```
 
+GRPC Health Checking example: See [document](https://github.com/grpc/grpc/blob/master/doc/health-checking.md).
+
+[embedmd]:# (rpc/example/go/send/main.go go)
+```go
+package main
+
+import (
+	"context"
+	"log"
+
+	"github.com/appleboy/gorush/rpc/proto"
+
+	"google.golang.org/grpc"
+)
+
+const (
+	address = "localhost:9000"
+)
+
+func main() {
+	// Set up a connection to the server.
+	conn, err := grpc.Dial(address, grpc.WithInsecure())
+	if err != nil {
+		log.Fatalf("did not connect: %v", err)
+	}
+	defer conn.Close()
+	c := proto.NewGorushClient(conn)
+
+	r, err := c.Send(context.Background(), &proto.NotificationRequest{
+		Platform: 2,
+		Tokens:   []string{"1234567890"},
+		Message:  "test message",
+	})
+	if err != nil {
+		log.Fatalf("could not greet: %v", err)
+	}
+	log.Printf("Success: %t\n", r.Success)
+	log.Printf("Count: %d\n", r.Counts)
+}
+```
+
 ## Run gorush in Docker
 
 Set up `gorush` in the cloud in under 5 minutes with zero knowledge of Golang or Linux shell using our [gorush Docker image](https://hub.docker.com/r/appleboy/gorush/).

rpc/client_grpc_health.go

@@ -2,7 +2,6 @@ package rpc
 
 import (
 	"context"
-	"time"
 
 	"github.com/appleboy/gorush/rpc/proto"
 
@@ -13,8 +12,6 @@ import (
 // generate protobuffs
 //   protoc --go_out=plugins=grpc,import_path=proto:. *.proto
 
-var backoff = time.Second
-
 type healthClient struct {
 	client proto.HealthClient
 	conn   *grpc.ClientConn
@@ -37,25 +34,24 @@ func (c *healthClient) Check(ctx context.Context) (bool, error) {
 	var err error
 	req := new(proto.HealthCheckRequest)
 
-	for {
-		res, err = c.client.Check(ctx, req)
-		if err == nil {
-			if res.GetStatus() == proto.HealthCheckResponse_SERVING {
-				return true, nil
-			}
-			return false, nil
+	res, err = c.client.Check(ctx, req)
+	if err == nil {
+		if res.GetStatus() == proto.HealthCheckResponse_SERVING {
+			return true, nil
 		}
-		switch grpc.Code(err) {
-		case
-			codes.Aborted,
-			codes.DataLoss,
-			codes.DeadlineExceeded,
-			codes.Internal,
-			codes.Unavailable:
-			// non-fatal errors
-		default:
-			return false, err
-		}
-		<-time.After(backoff)
+		return false, nil
 	}
+	switch grpc.Code(err) {
+	case
+		codes.Aborted,
+		codes.DataLoss,
+		codes.DeadlineExceeded,
+		codes.Internal,
+		codes.Unavailable:
+		// non-fatal errors
+	default:
+		return false, err
+	}
+
+	return false, err
 }

rpc/example/go/health/main.go

@@ -1,11 +1,12 @@
 package main
 
 import (
+	"context"
 	"log"
+	"time"
 
-	"github.com/appleboy/gorush/rpc/proto"
+	"github.com/appleboy/gorush/rpc"
 
-	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
 
@@ -21,10 +22,16 @@ func main() {
 	}
 	defer conn.Close()
 
-	c := proto.NewHealthClient(conn)
-	r, err := c.Check(context.Background(), &proto.HealthCheckRequest{})
-	if err != nil {
-		log.Fatalf("could not greet: %v", err)
+	client := rpc.NewGrpcHealthClient(conn)
+
+	for {
+		ok, err := client.Check(context.Background())
+		if !ok || err != nil {
+			log.Printf("can't connect grpc server: %v, code: %v\n", err, grpc.Code(err))
+		} else {
+			log.Println("connect the grpc server successfully")
+		}
+
+		<-time.After(time.Second)
 	}
-	log.Printf("Health: %d\n", r.GetStatus())
 }

rpc/example/go/send/main.go

@@ -1,11 +1,11 @@
 package main
 
 import (
+	"context"
 	"log"
 
 	"github.com/appleboy/gorush/rpc/proto"
 
-	"golang.org/x/net/context"
 	"google.golang.org/grpc"
 )
 

vendor/golang.org/x/net/context/context.go

@@ -5,6 +5,8 @@
 // Package context defines the Context type, which carries deadlines,
 // cancelation signals, and other request-scoped values across API boundaries
 // and between processes.
+// As of Go 1.7 this package is available in the standard library under the
+// name context.  https://golang.org/pkg/context.
 //
 // Incoming requests to a server should create a Context, and outgoing calls to
 // servers should accept a Context. The chain of function calls between must

vendor/vendor.json

@@ -585,10 +585,10 @@
 			"revisionTime": "2017-02-08T20:51:15Z"
 		},
 		{
-			"checksumSHA1": "dr5+PfIRzXeN+l1VG+s0lea9qz8=",
+			"checksumSHA1": "GtamqiJoL7PGHsN454AoffBFMa8=",
 			"path": "golang.org/x/net/context",
-			"revision": "ab5485076ff3407ad2d02db054635913f017b0ed",
-			"revisionTime": "2017-07-19T21:11:51Z"
+			"revision": "a337091b0525af65de94df2eb7e98bd9962dcbe2",
+			"revisionTime": "2016-10-09T20:39:03Z"
 		},
 		{
 			"checksumSHA1": "WHc3uByvGaMcnSoI21fhzYgbOgg=",