From 424e0cf73c4dc6c719c9e682b39ec2d17f63820c Mon Sep 17 00:00:00 2001
From: Umputun <umputun@gmail.com>
Date: Fri, 8 Jun 2018 03:12:22 -0500
Subject: [PATCH] proxy client with retry

---
 app/rest/proxy/avatar.go       | 20 ++++++++++++++++++--
 app/rest/proxy/avatar_store.go |  6 +++---
 app/rest/proxy/avatar_test.go  | 22 ++++++++++++++++++++++
 app/rest/proxy/image.go        |  8 +++++++-
 4 files changed, 50 insertions(+), 6 deletions(-)

diff --git a/app/rest/proxy/avatar.go b/app/rest/proxy/avatar.go
index 8b4ec746..0c085a33 100644
--- a/app/rest/proxy/avatar.go
+++ b/app/rest/proxy/avatar.go
@@ -40,10 +40,16 @@ func (p *Avatar) Put(u store.User) (avatarURL string, err error) {
 
 	// load avatar from remote location
 	client := http.Client{Timeout: 10 * time.Second}
-	resp, err := client.Get(u.Picture)
+	var resp *http.Response
+	err = retry(5, time.Second, func() error {
+		var e error
+		resp, e = client.Get(u.Picture)
+		return e
+	})
 	if err != nil {
-		return "", errors.Wrapf(err, "failed to get avatar for user %s from %s", u.ID, u.Picture)
+		return "", errors.Wrap(err, "failed to fetch avatar from the orig")
 	}
+
 	defer func() {
 		if e := resp.Body.Close(); e != nil {
 			log.Printf("[WARN] can't close response body, %s", e)
@@ -106,3 +112,13 @@ func (p *Avatar) Routes(middlewares ...func(http.Handler) http.Handler) (string,
 
 	return p.RoutePath, router
 }
+
+func retry(retries int, delay time.Duration, fn func() error) (err error) {
+	for i := 0; i < retries; i++ {
+		if err = fn(); err == nil {
+			return nil
+		}
+		time.Sleep(delay)
+	}
+	return errors.Wrap(err, "retry failed")
+}
diff --git a/app/rest/proxy/avatar_store.go b/app/rest/proxy/avatar_store.go
index 2db744ea..783544a4 100644
--- a/app/rest/proxy/avatar_store.go
+++ b/app/rest/proxy/avatar_store.go
@@ -17,8 +17,8 @@ import (
 
 // AvatarStore defines interface to store and serve avatars
 type AvatarStore interface {
-	Put(userID string, reader io.Reader) (avatarURL string, err error)
-	Get(userID string) (reader io.ReadCloser, size int, err error)
+	Put(userID string, reader io.Reader) (avatar string, err error)
+	Get(avatar string) (reader io.ReadCloser, size int, err error)
 }
 
 // FSAvatarStore implements AvatarStore for local file system
@@ -33,7 +33,7 @@ func NewFSAvatarStore(storePath string) *FSAvatarStore {
 	return &FSAvatarStore{storePath: storePath}
 }
 
-// Put avatar for userID to file and return avatar name
+// Put avatar for userID to file and return avatar's file name (base), like 12345678.image
 func (fs *FSAvatarStore) Put(userID string, reader io.Reader) (avatar string, err error) {
 
 	id := store.EncodeID(userID)
diff --git a/app/rest/proxy/avatar_test.go b/app/rest/proxy/avatar_test.go
index 8da97a92..bd8d6c25 100644
--- a/app/rest/proxy/avatar_test.go
+++ b/app/rest/proxy/avatar_test.go
@@ -2,6 +2,7 @@ package proxy
 
 import (
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"log"
@@ -9,6 +10,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -118,3 +120,23 @@ func TestAvatar_Routes(t *testing.T) {
 	assert.Equal(t, int64(21), sz)
 	assert.Equal(t, "some picture bin data", bb.String())
 }
+
+func TestAvatar_Retry(t *testing.T) {
+	i := 0
+	err := retry(5, time.Millisecond, func() error {
+		if i == 3 {
+			return nil
+		}
+		i++
+		return errors.New("err")
+	})
+	assert.Nil(t, err)
+	assert.Equal(t, 3, i)
+
+	st := time.Now()
+	err = retry(5, time.Millisecond, func() error {
+		return errors.New("err")
+	})
+	assert.NotNil(t, err)
+	assert.True(t, time.Since(st) >= time.Microsecond*5)
+}
diff --git a/app/rest/proxy/image.go b/app/rest/proxy/image.go
index 3b211aa4..087c235e 100644
--- a/app/rest/proxy/image.go
+++ b/app/rest/proxy/image.go
@@ -48,8 +48,14 @@ func (p Image) Routes() chi.Router {
 			rest.SendErrorJSON(w, r, http.StatusBadRequest, err, "can't decode image url")
 			return
 		}
+
 		client := http.Client{Timeout: 30 * time.Second}
-		resp, err := client.Get(string(src))
+		var resp *http.Response
+		err = retry(5, time.Second, func() error {
+			var e error
+			resp, e = client.Get(string(src))
+			return e
+		})
 		if err != nil {
 			rest.SendErrorJSON(w, r, http.StatusBadRequest, err, "can't get image "+string(src))
 			return