From e8f1b88d37ffc20a353e4491f76c2e64060bc3f2 Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Thu, 15 Mar 2018 16:53:13 +0100
Subject: [PATCH 1/3] Use Request context for HTTPClient.Do

If the context is cancelled on the request the breaker considers that an error.

Instead of creating a new context, we use the one provided on the http.Request, which returns context.BackGround if none is set.
---
 client.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/client.go b/client.go
index e91c52b..3127e07 100644
--- a/client.go
+++ b/client.go
@@ -94,7 +94,8 @@ func (c *HTTPClient) Do(req *http.Request) (*http.Response, error) {
 	var resp *http.Response
 	var err error
 	breaker := c.breakerLookup(req.URL.String())
-	err = breaker.Call(func() error {
+	ctx := req.Context()
+	err = breaker.CallContext(ctx, func() error {
 		resp, err = c.Client.Do(req)
 		return err
 	}, c.timeout)

From 1d961865afddae95b555549f393f6f387cae7475 Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Tue, 25 Sep 2018 15:48:03 +0200
Subject: [PATCH 2/3] Don't break on deadline exceeded.

---
 circuitbreaker.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/circuitbreaker.go b/circuitbreaker.go
index 620cd94..9636a5b 100644
--- a/circuitbreaker.go
+++ b/circuitbreaker.go
@@ -361,7 +361,9 @@ func (cb *Breaker) CallContext(ctx context.Context, circuit func() error, timeou
 	}
 
 	if err != nil {
-		if ctx.Err() != context.Canceled {
+		switch ctx.Err() {
+		case context.Canceled, context.DeadlineExceeded:
+		default:
 			cb.Fail()
 		}
 		return err

From 71b1aba38de5e8059c5aed541b19926bb63d22dc Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Tue, 25 Sep 2018 15:59:37 +0200
Subject: [PATCH 3/3] Report error if breaker is also timed out.

---
 circuitbreaker.go | 22 ++++++++++++++--------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/circuitbreaker.go b/circuitbreaker.go
index 9636a5b..f7288a6 100644
--- a/circuitbreaker.go
+++ b/circuitbreaker.go
@@ -360,17 +360,23 @@ func (cb *Breaker) CallContext(ctx context.Context, circuit func() error, timeou
 		}
 	}
 
-	if err != nil {
-		switch ctx.Err() {
-		case context.Canceled, context.DeadlineExceeded:
-		default:
+	if err == nil {
+		cb.Success()
+		return nil
+	}
+
+	switch ctx.Err() {
+	case context.Canceled:
+	case context.DeadlineExceeded:
+		// If the breaker timed out as well, report that,
+		// otherwise consider it "neutral".
+		if err == ErrBreakerTimeout {
 			cb.Fail()
 		}
-		return err
+	default:
+		cb.Fail()
 	}
-
-	cb.Success()
-	return nil
+	return err
 }
 
 // state returns the state of the TrippableBreaker. The states available are: