From d3a76e646ad2f88d0e50f5ddf4bef8d859b7be59 Mon Sep 17 00:00:00 2001
From: Asim Aslam <asim@chuhnk.me>
Date: Sun, 22 Jul 2018 17:41:58 +0100
Subject: [PATCH] retry only on timeout or internal server error

---
 client/client.go          |  2 +-
 client/retry.go           | 26 ++++++++++++++++++++++++--
 client/rpc_client_test.go |  4 ++--
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/client/client.go b/client/client.go
index 87cdad01..74ec51be 100644
--- a/client/client.go
+++ b/client/client.go
@@ -68,7 +68,7 @@ var (
 	// DefaultBackoff is the default backoff function for retries
 	DefaultBackoff = exponentialBackoff
 	// DefaultRetry is the default check-for-retry function for retries
-	DefaultRetry = alwaysRetry
+	DefaultRetry = RetryOnError
 	// DefaultRetries is the default number of times a request is tried
 	DefaultRetries = 1
 	// DefaultRequestTimeout is the default request timeout
diff --git a/client/retry.go b/client/retry.go
index c094b4ea..46466d48 100644
--- a/client/retry.go
+++ b/client/retry.go
@@ -2,12 +2,34 @@ package client
 
 import (
 	"context"
+
+	"github.com/micro/go-micro/errors"
 )
 
 // note that returning either false or a non-nil error will result in the call not being retried
 type RetryFunc func(ctx context.Context, req Request, retryCount int, err error) (bool, error)
 
-// always retry on error
-func alwaysRetry(ctx context.Context, req Request, retryCount int, err error) (bool, error) {
+// RetryAlways always retry on error
+func RetryAlways(ctx context.Context, req Request, retryCount int, err error) (bool, error) {
 	return true, nil
 }
+
+// RetryOnError retries a request on a 500 or timeout error
+func RetryOnError(ctx context.Context, req Request, retryCount int, err error) (bool, error) {
+	if err == nil {
+		return false, nil
+	}
+
+	e := errors.Parse(err.Error())
+	if e == nil {
+		return false, nil
+	}
+
+	switch e.Code {
+	// retry on timeout or internal server error
+	case 408, 500:
+		return true, nil
+	default:
+		return false, nil
+	}
+}
diff --git a/client/rpc_client_test.go b/client/rpc_client_test.go
index fde49ffc..6bafbdf5 100644
--- a/client/rpc_client_test.go
+++ b/client/rpc_client_test.go
@@ -2,10 +2,10 @@ package client
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"testing"
 
+	"github.com/micro/go-micro/errors"
 	"github.com/micro/go-micro/registry"
 	"github.com/micro/go-micro/registry/mock"
 	"github.com/micro/go-micro/selector"
@@ -69,7 +69,7 @@ func TestCallRetry(t *testing.T) {
 		return func(ctx context.Context, addr string, req Request, rsp interface{}, opts CallOptions) error {
 			called++
 			if called == 1 {
-				return errors.New("retry request")
+				return errors.InternalServerError("test.error", "retry request")
 			}
 
 			// don't do the call