common/lhttp: only retry transient errors

common/lhttp/client.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 package lhttp
 
 import (
         "bytes"
         "encoding/json"
         "fmt"
@@ skipping 21 matching lines @@
 // multiple times if an operation needs to be retried. The HTTP server is
 // responsible for closing the Request body, as per http.Request Body method
 // documentation.
 type RequestGen func() (*http.Request, error)
 
 // NewRequest returns a retriable request.
 //
 // The handler func is responsible for closing the response Body before
 // returning. It should return retry.Error in case of retriable error, for
 // example if a TCP connection is terminated while receiving the content.
+//
+// If rFn is nil, NewRequest will use a default exponential backoff strategy only

[dsansome-google, 2016/12/13 02:36:14]

Wrap to 80-chars like the other comments

+// for transient errors.
 func NewRequest(ctx context.Context, c *http.Client, rFn retry.Factory, rgen RequestGen, handler Handler) func() (int, error) {
         if rFn == nil {
-                rFn = retry.Default
+                rFn = retry.TransientOnly(retry.Default)
         }
 
         return func() (int, error) {
                 status, attempts := 0, 0
                 err := retry.Retry(ctx, rFn, func() error {
                         attempts++
                         req, err := rgen()
                         if err != nil {
                                 return err
                         }
@@ skipping 95 matching lines @@
 }
 
 // PostJSON is a shorthand. It returns the HTTP status code and error if any.
 func PostJSON(ctx context.Context, rFn retry.Factory, c *http.Client, url string, headers map[string]string, in, out interface{}) (int, error) {
         req, err := NewRequestJSON(ctx, c, rFn, url, "POST", headers, in, out)
         if err != nil {
                 return 0, err
         }
         return req()
 }