From 5d740dce6a8c0e34f3a812d76b30378475bff95f Mon Sep 17 00:00:00 2001
From: Justin Santa Barbara <justin@fathomdb.com>
Date: Mon, 16 Jan 2017 10:16:24 -0500
Subject: [PATCH] dnsprovider: Add IsEmpty method

When batching changes, it is often handy to know whether a changeset
IsEmpty, and thus does not need to be Apply-ed.
---
 federation/pkg/dnsprovider/dns.go                             | 4 +++-
 .../pkg/dnsprovider/providers/aws/route53/rrchangeset.go      | 4 ++++
 federation/pkg/dnsprovider/providers/coredns/rrchangeset.go   | 4 ++++
 .../pkg/dnsprovider/providers/google/clouddns/rrchangeset.go  | 4 ++++
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/federation/pkg/dnsprovider/dns.go b/federation/pkg/dnsprovider/dns.go
index 6676c326918..39f322657f7 100644
--- a/federation/pkg/dnsprovider/dns.go
+++ b/federation/pkg/dnsprovider/dns.go
@@ -45,7 +45,7 @@ type Zone interface {
 	Name() string
 	// ID returns the unique provider identifier for the zone
 	ID() string
-	// ResourceRecordsets returns the provider's ResourceRecordSets interface, or false if not supported.
+	// ResourceRecordSets returns the provider's ResourceRecordSets interface, or false if not supported.
 	ResourceRecordSets() (ResourceRecordSets, bool)
 }
 
@@ -70,6 +70,8 @@ type ResourceRecordChangeset interface {
 	Remove(ResourceRecordSet) ResourceRecordChangeset
 	// Apply applies the accumulated operations to the Zone.
 	Apply() error
+	// IsEmpty returns true if there are no accumulated operations.
+	IsEmpty() bool
 }
 
 type ResourceRecordSet interface {
diff --git a/federation/pkg/dnsprovider/providers/aws/route53/rrchangeset.go b/federation/pkg/dnsprovider/providers/aws/route53/rrchangeset.go
index 2ec0c9e0317..5acfd33939e 100644
--- a/federation/pkg/dnsprovider/providers/aws/route53/rrchangeset.go
+++ b/federation/pkg/dnsprovider/providers/aws/route53/rrchangeset.go
@@ -99,3 +99,7 @@ func (c *ResourceRecordChangeset) Apply() error {
 	}
 	return nil
 }
+
+func (c *ResourceRecordChangeset) IsEmpty() bool {
+	return len(c.removals) == 0 && len(c.additions) == 0
+}
diff --git a/federation/pkg/dnsprovider/providers/coredns/rrchangeset.go b/federation/pkg/dnsprovider/providers/coredns/rrchangeset.go
index 8820ab463f6..e056339fa9d 100644
--- a/federation/pkg/dnsprovider/providers/coredns/rrchangeset.go
+++ b/federation/pkg/dnsprovider/providers/coredns/rrchangeset.go
@@ -58,6 +58,10 @@ func (c *ResourceRecordChangeset) Remove(rrset dnsprovider.ResourceRecordSet) dn
 	return c
 }
 
+func (c *ResourceRecordChangeset) IsEmpty() bool {
+	return len(c.changeset) == 0
+}
+
 func (c *ResourceRecordChangeset) Apply() error {
 	ctx := context.Background()
 	etcdPathPrefix := c.zone.zones.intf.etcdPathPrefix
diff --git a/federation/pkg/dnsprovider/providers/google/clouddns/rrchangeset.go b/federation/pkg/dnsprovider/providers/google/clouddns/rrchangeset.go
index f38f19dd217..d30df2f5f51 100644
--- a/federation/pkg/dnsprovider/providers/google/clouddns/rrchangeset.go
+++ b/federation/pkg/dnsprovider/providers/google/clouddns/rrchangeset.go
@@ -72,3 +72,7 @@ func (c *ResourceRecordChangeset) Apply() error {
 
 	return nil
 }
+
+func (c *ResourceRecordChangeset) IsEmpty() bool {
+	return len(c.additions) == 0 && len(c.removals) == 0
+}