Implementing select random outbound

option/group.go

@@ -13,4 +13,5 @@ type URLTestOutboundOptions struct {
 	Tolerance                 uint16   `json:"tolerance,omitempty"`
 	IdleTimeout               Duration `json:"idle_timeout,omitempty"`
 	InterruptExistConnections bool     `json:"interrupt_exist_connections,omitempty"`
+	Randomized                bool     `json:"randomized,omitempty"`
 }

outbound/urltest.go

@@ -2,6 +2,7 @@ package outbound
 
 import (
 	"context"
+	"math/rand"
 	"net"
 	"sync"
 	"time"
@@ -38,6 +39,7 @@ type URLTest struct {
 	idleTimeout                  time.Duration
 	group                        *URLTestGroup
 	interruptExternalConnections bool
+	randomized                   bool
 }
 
 func NewURLTest(ctx context.Context, router adapter.Router, logger log.ContextLogger, tag string, options option.URLTestOutboundOptions) (*URLTest, error) {
@@ -57,6 +59,7 @@ func NewURLTest(ctx context.Context, router adapter.Router, logger log.ContextLo
 		tolerance:                    options.Tolerance,
 		idleTimeout:                  time.Duration(options.IdleTimeout),
 		interruptExternalConnections: options.InterruptExistConnections,
+		randomized:                   options.Randomized,
 	}
 	if len(outbound.tags) == 0 {
 		return nil, E.New("missing tags")
@@ -83,6 +86,7 @@ func (s *URLTest) Start() error {
 		s.tolerance,
 		s.idleTimeout,
 		s.interruptExternalConnections,
+		s.randomized,
 	)
 	if err != nil {
 		return err
@@ -126,6 +130,9 @@ func (s *URLTest) CheckOutbounds() {
 func (s *URLTest) DialContext(ctx context.Context, network string, destination M.Socksaddr) (net.Conn, error) {
 	s.group.Touch()
 	var outbound adapter.Outbound
+	if s.randomized {
+		outbound = s.group.selectRandomOutbound(network)
+	} else {
 		switch N.NetworkName(network) {
 		case N.NetworkTCP:
 			outbound = s.group.selectedOutboundTCP
@@ -137,6 +144,7 @@ func (s *URLTest) DialContext(ctx context.Context, network string, destination M
 		if outbound == nil {
 			outbound, _ = s.group.Select(network)
 		}
+	}
 	if outbound == nil {
 		return nil, E.New("missing supported outbound")
 	}
@@ -151,10 +159,15 @@ func (s *URLTest) DialContext(ctx context.Context, network string, destination M
 
 func (s *URLTest) ListenPacket(ctx context.Context, destination M.Socksaddr) (net.PacketConn, error) {
 	s.group.Touch()
-	outbound := s.group.selectedOutboundUDP
+	var outbound adapter.Outbound
+	if s.randomized {
+		outbound = s.group.selectRandomOutbound(N.NetworkUDP) // Since ListenPacket is for UDP, we pass "N.NetworkUDP" as the network type
+	} else {
+		outbound = s.group.selectedOutboundUDP
 		if outbound == nil {
 			outbound, _ = s.group.Select(N.NetworkUDP)
 		}
+	}
 	if outbound == nil {
 		return nil, E.New("missing supported outbound")
 	}
@@ -196,6 +209,9 @@ type URLTestGroup struct {
 	pauseManager                 pause.Manager
 	selectedOutboundTCP          adapter.Outbound
 	selectedOutboundUDP          adapter.Outbound
+	randomized					 bool
+	bestTCPLatencyOutbounds      []adapter.Outbound
+	bestUDPLatencyOutbounds      []adapter.Outbound
 	interruptGroup               *interrupt.Group
 	interruptExternalConnections bool
 	
@@ -216,6 +232,7 @@ func NewURLTestGroup(
 	tolerance uint16,
 	idleTimeout time.Duration,
 	interruptExternalConnections bool,
+	randomized bool,
 ) (*URLTestGroup, error) {
 	if interval == 0 {
 		interval = C.DefaultURLTestInterval
@@ -250,6 +267,7 @@ func NewURLTestGroup(
 		pauseManager:                 service.FromContext[pause.Manager](ctx),
 		interruptGroup:               interrupt.NewGroup(),
 		interruptExternalConnections: interruptExternalConnections,
+		randomized:					  randomized,
 	}, nil
 }
 
@@ -349,6 +367,9 @@ func (g *URLTestGroup) loopCheck() {
         }
         g.pauseManager.WaitActive()
         g.CheckOutbounds(false)
+		if g.randomized {
+			g.selectBestLatencyOutbounds()
+		}
     }
 }
 
@@ -357,7 +378,15 @@ func (g *URLTestGroup) CheckOutbounds(force bool) {
 }
 
 func (g *URLTestGroup) URLTest(ctx context.Context) (map[string]uint16, error) {
-	return g.urlTest(ctx, false)
+	result, err := g.urlTest(ctx, false)
+    if err != nil {
+        return nil, err
+    }
+
+	if g.randomized {
+		g.selectBestLatencyOutbounds()
+	}
+    return result, nil
 }
 
 func (g *URLTestGroup) urlTest(ctx context.Context, force bool) (map[string]uint16, error) {
@@ -423,3 +452,69 @@ func (g *URLTestGroup) performUpdateCheck() {
 		g.interruptGroup.Interrupt(g.interruptExternalConnections)
 	}
 }
+
+func (g *URLTestGroup) selectBestLatencyOutbounds() {
+    var bestTCPLatency uint16
+    var bestUDPLatency uint16
+
+    var bestTCPOutbounds []adapter.Outbound
+    var bestUDPOutbounds []adapter.Outbound
+
+    for _, detour := range g.outbounds {
+        history := g.history.LoadURLTestHistory(RealTag(detour))
+        if history == nil {
+            continue
+        }
+        
+        if common.Contains(detour.Network(), N.NetworkTCP) {
+            if bestTCPLatency == 0 || history.Delay < bestTCPLatency {
+                bestTCPLatency = history.Delay
+            }
+        } else if common.Contains(detour.Network(), N.NetworkUDP) {
+            if bestUDPLatency == 0 || history.Delay < bestUDPLatency {
+                bestUDPLatency = history.Delay
+            }
+        }
+    }
+
+    for _, detour := range g.outbounds {
+        history := g.history.LoadURLTestHistory(RealTag(detour))
+        if history == nil {
+            continue
+        }
+
+        if common.Contains(detour.Network(), N.NetworkTCP) && history.Delay <= bestTCPLatency+g.tolerance {
+            bestTCPOutbounds = append(bestTCPOutbounds, detour)
+        } else if common.Contains(detour.Network(), N.NetworkUDP) && history.Delay <= bestUDPLatency+g.tolerance {
+            bestUDPOutbounds = append(bestUDPOutbounds, detour)
+        }
+    }
+
+    g.bestTCPLatencyOutbounds = bestTCPOutbounds
+    g.bestUDPLatencyOutbounds = bestUDPOutbounds
+}
+
+// selectRandomOutbound selects an outbound randomly among the outbounds with the best latency
+func (g *URLTestGroup) selectRandomOutbound(network string) adapter.Outbound {
+    var bestOutbounds []adapter.Outbound
+
+    switch network {
+    case N.NetworkTCP:
+        bestOutbounds = g.bestTCPLatencyOutbounds
+    case N.NetworkUDP:
+        bestOutbounds = g.bestUDPLatencyOutbounds
+    default:
+        return nil
+    }
+
+    if len(bestOutbounds) == 0 {
+        return nil
+    }
+
+    randIndex := rand.Intn(len(bestOutbounds))
+	g.logger.Debug("Random outbound selection: ", bestOutbounds[randIndex].Tag())
+	
+    return bestOutbounds[randIndex]
+}
+
+