From c57f8cfa660aacfa5c9dd2d58885ec7e3f286e04 Mon Sep 17 00:00:00 2001
From: funkygao <funky.gao@gmail.com>
Date: Thu, 12 Nov 2015 22:12:43 +0800
Subject: [PATCH 1/3] client will export isr info of a topic/partition

---
 client.go | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/client.go b/client.go
index 210dd9a38..ef19b2992 100644
--- a/client.go
+++ b/client.go
@@ -295,6 +295,31 @@ func (client *client) Replicas(topic string, partitionID int32) ([]int32, error)
 	return dupeAndSort(metadata.Replicas), nil
 }
 
+func (client *client) Isr(topic string, partitionID int32) ([]int32, error) {
+	if client.Closed() {
+		return nil, ErrClosedClient
+	}
+
+	metadata := client.cachedMetadata(topic, partitionID)
+
+	if metadata == nil {
+		err := client.RefreshMetadata(topic)
+		if err != nil {
+			return nil, err
+		}
+		metadata = client.cachedMetadata(topic, partitionID)
+	}
+
+	if metadata == nil {
+		return nil, ErrUnknownTopicOrPartition
+	}
+
+	if metadata.Err == ErrReplicaNotAvailable {
+		return nil, metadata.Err
+	}
+	return dupeAndSort(metadata.Isr), nil
+}
+
 func (client *client) Leader(topic string, partitionID int32) (*Broker, error) {
 	if client.Closed() {
 		return nil, ErrClosedClient

From f79a4d6153050d0d1e223e5d3d254542e26d466b Mon Sep 17 00:00:00 2001
From: Kyle Hargraves <pd@krh.me>
Date: Mon, 1 May 2017 11:48:28 -0500
Subject: [PATCH 2/3] Add Isr to Client interface

---
 client.go      |  3 +++
 client_test.go | 11 +++++++++++
 2 files changed, 14 insertions(+)

diff --git a/client.go b/client.go
index ef19b2992..615ef9761 100644
--- a/client.go
+++ b/client.go
@@ -38,6 +38,9 @@ type Client interface {
 	// Replicas returns the set of all replica IDs for the given partition.
 	Replicas(topic string, partitionID int32) ([]int32, error)
 
+	// Isr returns the set of in-sync replica IDs for the given partition.
+	Isr(topic string, partitionID int32) ([]int32, error)
+
 	// RefreshMetadata takes a list of topics and queries the cluster to refresh the
 	// available metadata for those topics. If no topics are provided, it will refresh
 	// metadata for all topics.
diff --git a/client_test.go b/client_test.go
index b0559466f..85a97d174 100644
--- a/client_test.go
+++ b/client_test.go
@@ -196,6 +196,17 @@ func TestClientMetadata(t *testing.T) {
 		t.Error("Incorrect (or unsorted) replica")
 	}
 
+	isr, err = client.Isr("my_topic", 0)
+	if err != nil {
+		t.Error(err)
+	} else if len(isr) != 2 {
+		t.Error("Client returned incorrect ISRs for partition:", isr)
+	} else if isr[0] != 1 {
+		t.Error("Incorrect (or unsorted) ISR:", isr)
+	} else if isr[1] != 5 {
+		t.Error("Incorrect (or unsorted) ISR:", isr)
+	}
+
 	leader.Close()
 	seedBroker.Close()
 	safeClose(t, client)

From dbc0382c178bf0da82e37b98b9b9434feddfc264 Mon Sep 17 00:00:00 2001
From: Kyle Hargraves <pd@krh.me>
Date: Mon, 1 May 2017 14:19:41 -0500
Subject: [PATCH 3/3] Rename client.Isr to client.InSyncReplicas

---
 client.go      | 8 +++++---
 client_test.go | 2 +-
 2 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/client.go b/client.go
index 615ef9761..45de3973d 100644
--- a/client.go
+++ b/client.go
@@ -38,8 +38,10 @@ type Client interface {
 	// Replicas returns the set of all replica IDs for the given partition.
 	Replicas(topic string, partitionID int32) ([]int32, error)
 
-	// Isr returns the set of in-sync replica IDs for the given partition.
-	Isr(topic string, partitionID int32) ([]int32, error)
+	// InSyncReplicas returns the set of all in-sync replica IDs for the given
+	// partition. In-sync replicas are replicas which are fully caught up with
+	// the partition leader.
+	InSyncReplicas(topic string, partitionID int32) ([]int32, error)
 
 	// RefreshMetadata takes a list of topics and queries the cluster to refresh the
 	// available metadata for those topics. If no topics are provided, it will refresh
@@ -298,7 +300,7 @@ func (client *client) Replicas(topic string, partitionID int32) ([]int32, error)
 	return dupeAndSort(metadata.Replicas), nil
 }
 
-func (client *client) Isr(topic string, partitionID int32) ([]int32, error) {
+func (client *client) InSyncReplicas(topic string, partitionID int32) ([]int32, error) {
 	if client.Closed() {
 		return nil, ErrClosedClient
 	}
diff --git a/client_test.go b/client_test.go
index 85a97d174..0bac1b405 100644
--- a/client_test.go
+++ b/client_test.go
@@ -196,7 +196,7 @@ func TestClientMetadata(t *testing.T) {
 		t.Error("Incorrect (or unsorted) replica")
 	}
 
-	isr, err = client.Isr("my_topic", 0)
+	isr, err = client.InSyncReplicas("my_topic", 0)
 	if err != nil {
 		t.Error(err)
 	} else if len(isr) != 2 {