Merge pull request #13161 from calavera/plugin_discovery

Proposal: Volume refactor and external volume plugins

plugins/client.go

@@ -31,6 +31,10 @@ type Client struct {
 }
 
 func (c *Client) Call(serviceMethod string, args interface{}, ret interface{}) error {
+	return c.callWithRetry(serviceMethod, args, ret, true)
+}
+
+func (c *Client) callWithRetry(serviceMethod string, args interface{}, ret interface{}, retry bool) error {
 	var buf bytes.Buffer
 	if err := json.NewEncoder(&buf).Encode(args); err != nil {
 		return err
@@ -50,12 +54,16 @@ func (c *Client) Call(serviceMethod string, args interface{}, ret interface{}) e
 	for {
 		resp, err := c.http.Do(req)
 		if err != nil {
+			if !retry {
+				return err
+			}
+
 			timeOff := backoff(retries)
-			if timeOff+time.Since(start) > defaultTimeOut {
+			if abort(start, timeOff) {
 				return err
 			}
 			retries++
-			logrus.Warn("Unable to connect to plugin: %s, retrying in %ds\n", c.addr, timeOff)
+			logrus.Warnf("Unable to connect to plugin: %s, retrying in %v", c.addr, timeOff)
 			time.Sleep(timeOff)
 			continue
 		}
@@ -73,7 +81,7 @@ func (c *Client) Call(serviceMethod string, args interface{}, ret interface{}) e
 }
 
 func backoff(retries int) time.Duration {
-	b, max := float64(1), float64(defaultTimeOut)
+	b, max := 1, defaultTimeOut
 	for b < max && retries > 0 {
 		b *= 2
 		retries--
@@ -81,7 +89,11 @@ func backoff(retries int) time.Duration {
 	if b > max {
 		b = max
 	}
-	return time.Duration(b)
+	return time.Duration(b) * time.Second
+}
+
+func abort(start time.Time, timeOff time.Duration) bool {
+	return timeOff+time.Since(start) > time.Duration(defaultTimeOut)*time.Second
 }
 
 func configureTCPTransport(tr *http.Transport, proto, addr string) {

plugins/client_test.go

@@ -6,6 +6,7 @@ import (
 	"net/http/httptest"
 	"reflect"
 	"testing"
+	"time"
 )
 
 var (
@@ -27,7 +28,7 @@ func teardownRemotePluginServer() {
 
 func TestFailedConnection(t *testing.T) {
 	c := NewClient("tcp://127.0.0.1:1")
-	err := c.Call("Service.Method", nil, nil)
+	err := c.callWithRetry("Service.Method", nil, nil, false)
 	if err == nil {
 		t.Fatal("Unexpected successful connection")
 	}
@@ -61,3 +62,44 @@ func TestEchoInputOutput(t *testing.T) {
 		t.Fatalf("Expected %v, was %v\n", m, output)
 	}
 }
+
+func TestBackoff(t *testing.T) {
+	cases := []struct {
+		retries    int
+		expTimeOff time.Duration
+	}{
+		{0, time.Duration(1)},
+		{1, time.Duration(2)},
+		{2, time.Duration(4)},
+		{4, time.Duration(16)},
+		{6, time.Duration(30)},
+		{10, time.Duration(30)},
+	}
+
+	for _, c := range cases {
+		s := c.expTimeOff * time.Second
+		if d := backoff(c.retries); d != s {
+			t.Fatalf("Retry %v, expected %v, was %v\n", c.retries, s, d)
+		}
+	}
+}
+
+func TestAbortRetry(t *testing.T) {
+	cases := []struct {
+		timeOff  time.Duration
+		expAbort bool
+	}{
+		{time.Duration(1), false},
+		{time.Duration(2), false},
+		{time.Duration(10), false},
+		{time.Duration(30), true},
+		{time.Duration(40), true},
+	}
+
+	for _, c := range cases {
+		s := c.timeOff * time.Second
+		if a := abort(time.Now(), s); a != c.expAbort {
+			t.Fatalf("Duration %v, expected %v, was %v\n", c.timeOff, s, a)
+		}
+	}
+}