From 22a4d48cf967bffd26522d35a7b939e4d619f8ce Mon Sep 17 00:00:00 2001
From: zhengrui <zhengrui@zenmen.com>
Date: Sun, 18 Mar 2018 10:41:55 +0800
Subject: [PATCH] #224 add fifo strategy for node selector

---
 cmd/gost/main.go |  4 +++-
 selector.go      | 35 +++++++++++++++++++++++++++--------
 2 files changed, 30 insertions(+), 9 deletions(-)

diff --git a/cmd/gost/main.go b/cmd/gost/main.go
index 6cc244d..14f5062 100644
--- a/cmd/gost/main.go
+++ b/cmd/gost/main.go
@@ -488,7 +488,7 @@ func (r *route) serve() error {
 		case "sni":
 			handler = gost.SNIHandler(handlerOptions...)
 		default:
-			// start from 2.5, if remote is not empty, then we assume that it is a forward tunnel
+			// start from 2.5, if remote is not empty, then we assume that it is a forward tunnel.
 			if node.Remote != "" {
 				handler = gost.TCPDirectForwardHandler(node.Remote, handlerOptions...)
 			} else {
@@ -696,6 +696,8 @@ func parseStrategy(s string) gost.Strategy {
 	switch s {
 	case "random":
 		return &gost.RandomStrategy{}
+	case "fifo":
+		return &gost.FIFOStrategy{}
 	case "round":
 		fallthrough
 	default:
diff --git a/selector.go b/selector.go
index 15bbe33..cadf799 100644
--- a/selector.go
+++ b/selector.go
@@ -9,7 +9,7 @@ import (
 )
 
 var (
-	// ErrNoneAvailable indicates there is no node available
+	// ErrNoneAvailable indicates there is no node available.
 	ErrNoneAvailable = errors.New("none available")
 )
 
@@ -38,10 +38,10 @@ func (s *defaultSelector) Select(nodes []Node, opts ...SelectOption) (Node, erro
 	return sopts.Strategy.Apply(nodes), nil
 }
 
-// SelectOption used when making a select call
+// SelectOption is the option used when making a select call.
 type SelectOption func(*SelectOptions)
 
-// SelectOptions is the options for node selection
+// SelectOptions is the options for node selection.
 type SelectOptions struct {
 	Filters  []Filter
 	Strategy Strategy
@@ -62,18 +62,19 @@ func WithStrategy(s Strategy) SelectOption {
 	}
 }
 
-// Strategy is a selection strategy e.g random, round robin
+// Strategy is a selection strategy e.g random, round-robin.
 type Strategy interface {
 	Apply([]Node) Node
 	String() string
 }
 
-// RoundStrategy is a strategy for node selector
+// RoundStrategy is a strategy for node selector.
+// The node will be selected by round-robin algorithm.
 type RoundStrategy struct {
 	count uint64
 }
 
-// Apply applies the round robin strategy for the nodes
+// Apply applies the round-robin strategy for the nodes.
 func (s *RoundStrategy) Apply(nodes []Node) Node {
 	if len(nodes) == 0 {
 		return Node{}
@@ -87,14 +88,15 @@ func (s *RoundStrategy) String() string {
 	return "round"
 }
 
-// RandomStrategy is a strategy for node selector
+// RandomStrategy is a strategy for node selector.
+// The node will be selected randomly.
 type RandomStrategy struct {
 	Seed int64
 	rand *rand.Rand
 	once sync.Once
 }
 
-// Apply applies the random strategy for the nodes
+// Apply applies the random strategy for the nodes.
 func (s *RandomStrategy) Apply(nodes []Node) Node {
 	s.once.Do(func() {
 		seed := s.Seed
@@ -114,6 +116,23 @@ func (s *RandomStrategy) String() string {
 	return "random"
 }
 
+// FIFOStrategy is a strategy for node selector.
+// The node will be selected from first to last,
+// and will stick to the selected node until it is failed.
+type FIFOStrategy struct{}
+
+// Apply applies the fifo strategy for the nodes.
+func (s *FIFOStrategy) Apply(nodes []Node) Node {
+	if len(nodes) == 0 {
+		return Node{}
+	}
+	return nodes[0]
+}
+
+func (s *FIFOStrategy) String() string {
+	return "fifo"
+}
+
 // Filter is used to filter a node during the selection process
 type Filter interface {
 	Filter([]Node) []Node