Dedup policy implement between grpc and proxy plugin (#3537)

Signed-off-by: zouyee <zounengren@cmss.chinamobile.com>

3 files changed, 13 insertions, 70 deletions

diff --git a/plugin/grpc/grpc.go b/plugin/grpc/grpc.go
index 3dda225df..878b6c3f4 100644
--- a/plugin/grpc/grpc.go
+++ b/plugin/grpc/grpc.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/coredns/coredns/plugin"
 	"github.com/coredns/coredns/plugin/debug"
+	"github.com/coredns/coredns/plugin/pkg/policy"
 	"github.com/coredns/coredns/request"
 
 	"github.com/miekg/dns"
@@ -17,7 +18,7 @@ import (
 // It has a list of proxies each representing one upstream proxy.
 type GRPC struct {
 	proxies []*Proxy
-	p       Policy
+	p       policy.Policy
 
 	from    string
 	ignored []string
@@ -93,7 +94,7 @@ func (g *GRPC) ServeDNS(ctx context.Context, w dns.ResponseWriter, r *dns.Msg) (
 // NewGRPC returns a new GRPC.
 func newGRPC() *GRPC {
 	g := &GRPC{
-		p: new(random),
+		p: new(policy.Random),
 	}
 	return g
 }
@@ -126,6 +127,11 @@ func (g *GRPC) isAllowedDomain(name string) bool {
 }
 
 // List returns a set of proxies to be used for this client depending on the policy in p.
-func (g *GRPC) list() []*Proxy { return g.p.List(g.proxies) }
+func (g *GRPC) list() []*Proxy {
+	if len(g.p.List(g.proxies)) == 1 {
+		return g.p.List(g.proxies)[0].([]*Proxy)
+	}
+	return nil
+}
 
 const defaultTimeout = 5 * time.Second
diff --git a/plugin/grpc/policy.go b/plugin/grpc/policy.go
deleted file mode 100644
index 66351d822..000000000
--- a/plugin/grpc/policy.go
+++ /dev/null
@@ -1,64 +0,0 @@
-package grpc
-
-import (
-	"math/rand"
-	"sync/atomic"
-)
-
-// Policy defines a policy we use for selecting upstreams.
-type Policy interface {
-	List([]*Proxy) []*Proxy
-	String() string
-}
-
-// random is a policy that implements random upstream selection.
-type random struct{}
-
-func (r *random) String() string { return "random" }
-
-func (r *random) List(p []*Proxy) []*Proxy {
-	switch len(p) {
-	case 1:
-		return p
-	case 2:
-		if rand.Int()%2 == 0 {
-			return []*Proxy{p[1], p[0]} // swap
-		}
-		return p
-	}
-
-	perms := rand.Perm(len(p))
-	rnd := make([]*Proxy, len(p))
-
-	for i, p1 := range perms {
-		rnd[i] = p[p1]
-	}
-	return rnd
-}
-
-// roundRobin is a policy that selects hosts based on round robin ordering.
-type roundRobin struct {
-	robin uint32
-}
-
-func (r *roundRobin) String() string { return "round_robin" }
-
-func (r *roundRobin) List(p []*Proxy) []*Proxy {
-	poolLen := uint32(len(p))
-	i := atomic.AddUint32(&r.robin, 1) % poolLen
-
-	robin := []*Proxy{p[i]}
-	robin = append(robin, p[:i]...)
-	robin = append(robin, p[i+1:]...)
-
-	return robin
-}
-
-// sequential is a policy that selects hosts based on sequential ordering.
-type sequential struct{}
-
-func (r *sequential) String() string { return "sequential" }
-
-func (r *sequential) List(p []*Proxy) []*Proxy {
-	return p
-}
diff --git a/plugin/grpc/setup.go b/plugin/grpc/setup.go
index a234efb37..c178932c4 100644
--- a/plugin/grpc/setup.go
+++ b/plugin/grpc/setup.go
@@ -8,6 +8,7 @@ import (
 	"github.com/coredns/coredns/plugin"
 	"github.com/coredns/coredns/plugin/metrics"
 	"github.com/coredns/coredns/plugin/pkg/parse"
+	"github.com/coredns/coredns/plugin/pkg/policy"
 	pkgtls "github.com/coredns/coredns/plugin/pkg/tls"
 
 	"github.com/caddyserver/caddy"
@@ -132,11 +133,11 @@ func parseBlock(c *caddy.Controller, g *GRPC) error {
 		}
 		switch x := c.Val(); x {
 		case "random":
-			g.p = &random{}
+			g.p = &policy.Random{}
 		case "round_robin":
-			g.p = &roundRobin{}
+			g.p = &policy.RoundRobin{}
 		case "sequential":
-			g.p = &sequential{}
+			g.p = &policy.Sequential{}
 		default:
 			return c.Errf("unknown policy '%s'", x)
 		}