From 8ff05d8e38b24ccc2d7555e7578d361cdf2abded Mon Sep 17 00:00:00 2001
From: Andrew Gaul <andrew@gaul.org>
Date: Fri, 1 Feb 2019 19:46:06 -0800
Subject: [PATCH] Implement exponential backoff for 503

Amazon returns SlowDown when overloaded.  Also return ENOTSUP for 501
and immediately return EIO for 500 instead of retrying.  Fixes #603.
---
 src/curl.cpp | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/src/curl.cpp b/src/curl.cpp
index c7a4788..9976290 100644
--- a/src/curl.cpp
+++ b/src/curl.cpp
@@ -2065,7 +2065,7 @@ int S3fsCurl::RequestPerform(void)
   }
 
   // 1 attempt + retries...
-  for(int retrycnt = S3fsCurl::retries; 0 < retrycnt; retrycnt--){
+  for(int retrycnt = 0; retrycnt < S3fsCurl::retries; ++retrycnt){
     // Requests
     CURLcode curlCode = curl_easy_perform(hCurl);
 
@@ -2081,11 +2081,6 @@ int S3fsCurl::RequestPerform(void)
           S3FS_PRN_INFO3("HTTP response code %ld", LastResponseCode);
           return 0;
         }
-        if(500 <= LastResponseCode){
-          S3FS_PRN_ERR("HTTP response code = %ld Body Text: %s", LastResponseCode, (bodydata ? bodydata->str() : ""));
-          sleep(4);
-          break; 
-        }
 
         // Service response codes which are >= 300 && < 500
         switch(LastResponseCode){
@@ -2108,6 +2103,17 @@ int S3fsCurl::RequestPerform(void)
             S3FS_PRN_DBG("Body Text: %s", (bodydata ? bodydata->str() : ""));
             return -ENOENT;
 
+          case 501:
+            S3FS_PRN_INFO3("HTTP response code 501 was returned, returning ENOTSUP");
+            S3FS_PRN_DBG("Body Text: %s", (bodydata ? bodydata->str() : ""));
+            return -ENOTSUP;
+
+          case 503:
+            S3FS_PRN_INFO3("HTTP response code 503 was returned, slowing down");
+            S3FS_PRN_DBG("Body Text: %s", (bodydata ? bodydata->str() : ""));
+            sleep(4 << retry_count);
+            break;
+
           default:
             S3FS_PRN_ERR("HTTP response code %ld, returning EIO. Body Text: %s", LastResponseCode, (bodydata ? bodydata->str() : ""));
             return -EIO;