From 864ce5f946e1923900ba6fdb01921987451e7982 Mon Sep 17 00:00:00 2001
From: Wolfgang Ebner <wolfgang.ebner@catalysts.cc>
Date: Tue, 16 Jun 2015 20:39:42 +0200
Subject: [PATCH 1/3] proxy: handle canceled proxy request gracefully

when a client of the proxy server cancels a request the proxy should not
set the endpoint state to unavailable
---
 proxy/reverse.go | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/proxy/reverse.go b/proxy/reverse.go
index 0db5bd111..a707a38b1 100644
--- a/proxy/reverse.go
+++ b/proxy/reverse.go
@@ -90,6 +90,7 @@ func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request
 		return
 	}
 
+	requestCanceled := false
 	completeCh := make(chan bool, 1)
 	closeNotifier, ok := rw.(http.CloseNotifier)
 	if ok {
@@ -98,6 +99,8 @@ func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request
 			case <-closeNotifier.CloseNotify():
 				tp, ok := p.transport.(*http.Transport)
 				if ok {
+					requestCanceled = true
+					log.Printf("proxy: request from %v canceled", clientreq.RemoteAddr)
 					tp.CancelRequest(proxyreq)
 				}
 			case <-completeCh:
@@ -118,6 +121,9 @@ func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request
 		redirectRequest(proxyreq, ep.URL)
 
 		res, err = p.transport.RoundTrip(proxyreq)
+		if requestCanceled {
+			return
+		}
 		if err != nil {
 			log.Printf("proxy: failed to direct request to %s: %v", ep.URL.String(), err)
 			ep.Failed()

From 5e31854afd3da752f68736d8e7b798c72bbe4a00 Mon Sep 17 00:00:00 2001
From: Wolfgang Ebner <wolfgang.ebner@catalysts.cc>
Date: Wed, 17 Jun 2015 10:15:00 +0200
Subject: [PATCH 2/3] proxy: use atomic operations for requestCanceled flag

---
 proxy/reverse.go | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/proxy/reverse.go b/proxy/reverse.go
index a707a38b1..3a2bcf297 100644
--- a/proxy/reverse.go
+++ b/proxy/reverse.go
@@ -24,6 +24,7 @@ import (
 	"net/http"
 	"net/url"
 	"strings"
+	"sync/atomic"
 
 	"github.com/coreos/etcd/etcdserver/etcdhttp/httptypes"
 )
@@ -90,7 +91,7 @@ func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request
 		return
 	}
 
-	requestCanceled := false
+	var requestClosed int32
 	completeCh := make(chan bool, 1)
 	closeNotifier, ok := rw.(http.CloseNotifier)
 	if ok {
@@ -99,7 +100,7 @@ func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request
 			case <-closeNotifier.CloseNotify():
 				tp, ok := p.transport.(*http.Transport)
 				if ok {
-					requestCanceled = true
+					atomic.StoreInt32(&requestClosed, 1)
 					log.Printf("proxy: request from %v canceled", clientreq.RemoteAddr)
 					tp.CancelRequest(proxyreq)
 				}
@@ -121,7 +122,7 @@ func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request
 		redirectRequest(proxyreq, ep.URL)
 
 		res, err = p.transport.RoundTrip(proxyreq)
-		if requestCanceled {
+		if atomic.LoadInt32(&requestClosed) == 1 {
 			return
 		}
 		if err != nil {

From a6e61864773481e10da5fa882ce3e864f9c9d28d Mon Sep 17 00:00:00 2001
From: Wolfgang Ebner <wolfgang.ebner@catalysts.cc>
Date: Fri, 19 Jun 2015 08:45:45 +0200
Subject: [PATCH 3/3] proxy: always set requestClosed flag when client closes
 the connection prematurely

---
 proxy/reverse.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/proxy/reverse.go b/proxy/reverse.go
index 3a2bcf297..0d6822e52 100644
--- a/proxy/reverse.go
+++ b/proxy/reverse.go
@@ -98,10 +98,11 @@ func (p *reverseProxy) ServeHTTP(rw http.ResponseWriter, clientreq *http.Request
 		go func() {
 			select {
 			case <-closeNotifier.CloseNotify():
+				atomic.StoreInt32(&requestClosed, 1)
+				log.Printf("proxy: client %v closed request prematurely", clientreq.RemoteAddr)
+
 				tp, ok := p.transport.(*http.Transport)
 				if ok {
-					atomic.StoreInt32(&requestClosed, 1)
-					log.Printf("proxy: request from %v canceled", clientreq.RemoteAddr)
 					tp.CancelRequest(proxyreq)
 				}
 			case <-completeCh: