From d307d127bff93294f8d05dc334c857cb7dc6aa58 Mon Sep 17 00:00:00 2001
From: Marc MacLeod <Marc@Marcs-MacBook-Pro.local>
Date: Sun, 14 Dec 2014 14:47:43 -0500
Subject: [PATCH 1/2] MiddlewareChain implements Middleware interface

If, during ProcessRequest, a middleware returns a response or error, don't process the rest of the chain.
---
 middleware/chain.go | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/middleware/chain.go b/middleware/chain.go
index fca387d..3e9ce5b 100644
--- a/middleware/chain.go
+++ b/middleware/chain.go
@@ -3,6 +3,7 @@ package middleware
 import (
 	"fmt"
 	. "github.com/mailgun/vulcan/request"
+	"net/http"
 	"sort"
 	"sync"
 )
@@ -49,6 +50,25 @@ func (c *MiddlewareChain) GetIter() *MiddlewareIter {
 	}
 }
 
+func (c *MiddlewareChain) ProcessRequest(r Request) (*http.Response, error) {
+	it := c.chain.getIter()
+	for v := it.next(); v != nil; v = it.next() {
+		resp, err := v.(Middleware).ProcessRequest(r)
+		if resp != nil || err != nil {
+			break
+			return resp, err
+		}
+	}
+	return nil, nil
+}
+
+func (c *MiddlewareChain) ProcessResponse(r Request, a Attempt) {
+	it := c.chain.getReverseIter()
+	for v := it.next(); v != nil; v = it.next() {
+		v.(Middleware).ProcessResponse(r, a)
+	}
+}
+
 type MiddlewareIter struct {
 	iter *iter
 }

From ba137ab61ae846273287e88f5ae9ff1f1847a716 Mon Sep 17 00:00:00 2001
From: Marc MacLeod <Marc@Marcs-MacBook-Pro.local>
Date: Sun, 14 Dec 2014 14:47:43 -0500
Subject: [PATCH 2/2] MiddlewareChain implements Middleware interface

If, during ProcessRequest, a middleware returns a response or error, don't process the rest of the chain.

During ProcessResponse, only call the middleware that was called in ProcessResponse.
---
 middleware/chain.go | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/middleware/chain.go b/middleware/chain.go
index fca387d..9623dba 100644
--- a/middleware/chain.go
+++ b/middleware/chain.go
@@ -3,6 +3,7 @@ package middleware
 import (
 	"fmt"
 	. "github.com/mailgun/vulcan/request"
+	"net/http"
 	"sort"
 	"sync"
 )
@@ -49,6 +50,32 @@ func (c *MiddlewareChain) GetIter() *MiddlewareIter {
 	}
 }
 
+func (c *MiddlewareChain) ProcessRequest(r Request) (*http.Response, error) {
+	it := c.chain.getIter()
+	for v := it.next(); v != nil; v = it.next() {
+		// Track how deep we've gotten in the middleware chain
+		c.chain.callDepth = it.index + 1
+		resp, err := v.(Middleware).ProcessRequest(r)
+		if resp != nil || err != nil {
+			break
+			return resp, err
+		}
+	}
+	return nil, nil
+}
+
+func (c *MiddlewareChain) ProcessResponse(r Request, a Attempt) {
+	it := c.chain.getReverseIter()
+
+	// Set the iterator to start at the furthest spot we got in the chain during ProcessRequest
+	currentIndex := c.chain.callDepth
+	it.index = len(it.callbacks) - currentIndex
+
+	for v := it.next(); v != nil; v = it.next() {
+		v.(Middleware).ProcessResponse(r, a)
+	}
+}
+
 type MiddlewareIter struct {
 	iter *iter
 }
@@ -122,6 +149,7 @@ func (c *ObserverChain) ObserveResponse(r Request, a Attempt) {
 type chain struct {
 	mutex     *sync.RWMutex
 	callbacks []*callback
+	callDepth int            // how deep into the chain we get on ProcessRequest / ObserveRequest. 1 based
 	indexes   map[string]int // Indexes for in place updates
 	iter      *iter          //current version of iterator
 }