lua: unify IP slice access and cache slice metatables

common/geodata/lua.go

@@ -4,20 +4,6 @@ import (
 	xlua "github.com/xtls/xray-core/common/lua"
 	"github.com/xtls/xray-core/common/net"
 	lua "github.com/yuin/gopher-lua"
-	luar "layeh.com/gopher-luar"
-)
-
-var (
-	luaDomainDirectMethods = map[string]xlua.DirectMethod{
-		"Match":    luaDomainMatch,
-		"MatchAny": luaDomainMatchAny,
-	}
-	luaIPDirectMethods = map[string]xlua.DirectMethod{
-		"Match":     luaIPMatch,
-		"AnyMatch":  luaIPAnyMatch,
-		"Matches":   luaIPMatches,
-		"FilterIPs": luaIPFilterIPs,
-	}
 )
 
 // RegisterLua makes xray.geodata available to require in an LState.
@@ -36,7 +22,10 @@ func RegisterLua(L *lua.LState) {
 				L.RaiseError("%v", err)
 				return 0
 			}
-			xlua.PushWithDirectMethods(L, matcher, luaDomainDirectMethods)
+			xlua.PushWithDirectMethods(L, matcher, map[string]xlua.DirectMethod{
+				"Match":    newLuaDomainMatch(xlua.NewSlicePusher[uint32](L)),
+				"MatchAny": luaDomainMatchAny,
+			})
 			return 1
 		}))
 
@@ -51,9 +40,15 @@ func RegisterLua(L *lua.LState) {
 				L.RaiseError("%v", err)
 				return 0
 			}
-			xlua.PushWithDirectMethods(L, matcher, luaIPDirectMethods)
+			xlua.PushWithDirectMethods(L, matcher, map[string]xlua.DirectMethod{
+				"Match":     luaIPMatch,
+				"AnyMatch":  luaIPAnyMatch,
+				"Matches":   luaIPMatches,
+				"FilterIPs": newLuaIPFilterIPs(xlua.NewSlicePusher[net.IP](L)),
+			})
 			return 1
 		}))
+
 		L.Push(module)
 		return 1
 	})
@@ -111,29 +106,33 @@ func luaIPMatches(L *lua.LState) (int, bool) {
 	return 1, true
 }
 
-func luaIPFilterIPs(L *lua.LState) (int, bool) {
-	matcher, ips, ok := readLuaIPMatcherArgs[[]net.IP](L)
-	if !ok {
-		return 0, false
+func newLuaIPFilterIPs(pushIPs func(*lua.LState, []net.IP)) xlua.DirectMethod {
+	return func(L *lua.LState) (int, bool) {
+		matcher, ips, ok := readLuaIPMatcherArgs[[]net.IP](L)
+		if !ok {
+			return 0, false
+		}
+		matched, unmatched := matcher.FilterIPs(ips)
+		pushIPs(L, matched)
+		pushIPs(L, unmatched)
+		return 2, true
 	}
-	matched, unmatched := matcher.FilterIPs(ips)
-	L.Push(luar.New(L, matched))
-	L.Push(luar.New(L, unmatched))
-	return 2, true
 }
 
-func luaDomainMatch(L *lua.LState) (int, bool) {
-	if L.GetTop() == 2 {
-		if value, ok := L.Get(1).(*lua.LUserData); ok {
-			matcher, validMatcher := value.Value.(DomainMatcher)
-			domain, validDomain := L.Get(2).(lua.LString)
-			if validMatcher && validDomain {
-				L.Push(luar.New(L, matcher.Match(string(domain))))
-				return 1, true
+func newLuaDomainMatch(pushMatches func(*lua.LState, []uint32)) xlua.DirectMethod {
+	return func(L *lua.LState) (int, bool) {
+		if L.GetTop() == 2 {
+			if value, ok := L.Get(1).(*lua.LUserData); ok {
+				matcher, validMatcher := value.Value.(DomainMatcher)
+				domain, validDomain := L.Get(2).(lua.LString)
+				if validMatcher && validDomain {
+					pushMatches(L, matcher.Match(string(domain)))
+					return 1, true
+				}
 			}
 		}
+		return 0, false
 	}
-	return 0, false
 }
 
 func luaDomainMatchAny(L *lua.LState) (int, bool) {

common/lua/luar.go

@@ -5,6 +5,23 @@ import (
 	luar "layeh.com/gopher-luar"
 )
 
+// NewSlicePusher captures luar's slice metatable during state initialization.
+// The returned function wraps slices without reflection or metatable lookup,
+// and pushes nil for nil slices. Use it with this state or its coroutines.
+func NewSlicePusher[T any](L *glua.LState) func(*glua.LState, []T) {
+	metatable := luar.New(L, []T{}).(*glua.LUserData).Metatable
+	return func(L *glua.LState, values []T) {
+		if values == nil {
+			L.Push(glua.LNil)
+			return
+		}
+		userdata := L.NewUserData()
+		userdata.Value = values
+		userdata.Metatable = metatable
+		L.Push(userdata)
+	}
+}
+
 // DirectMethod handles a Lua call without luar's reflected method invocation.
 // It returns the result count and whether it handled the arguments. On false,
 // it must leave the stack unchanged for the original luar wrapper.

common/lua/luar_test.go

@@ -0,0 +1,84 @@
+package lua
+
+import (
+	"net"
+	"testing"
+
+	glua "github.com/yuin/gopher-lua"
+	luar "layeh.com/gopher-luar"
+)
+
+func TestSlicePusher(t *testing.T) {
+	L := glua.NewState()
+	defer L.Close()
+	push := NewSlicePusher[int](L)
+	values := []int{3, 5}
+	L.SetGlobal("getValues", L.NewFunction(func(L *glua.LState) int {
+		push(L, values)
+		return 1
+	}))
+	if err := L.DoString(`
+local values = getValues()
+assert(#values == 2 and values[1] == 3 and values[2] == 5)
+values[2] = 7
+local co = coroutine.create(function()
+    local values = getValues()
+    assert(#values == 2 and values[1] == 3 and values[2] == 7)
+    return true
+end)
+local ok, result = coroutine.resume(co)
+assert(ok and result == true)
+`); err != nil {
+		t.Fatal(err)
+	}
+	if values[1] != 7 {
+		t.Fatal("slice storage was copied")
+	}
+	push(L, nil)
+	if L.Get(-1) != glua.LNil {
+		t.Fatal("nil slice must push Lua nil")
+	}
+	L.Pop(1)
+	push(L, []int{})
+	L.SetGlobal("empty", L.Get(-1))
+	L.Pop(1)
+	if err := L.DoString(`assert(type(empty) == "userdata" and #empty == 0)`); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestSlicePusherMetatablePerState(t *testing.T) {
+	first := glua.NewState()
+	defer first.Close()
+	second := glua.NewState()
+	defer second.Close()
+	NewSlicePusher[int](first)(first, []int{1})
+	NewSlicePusher[int](second)(second, []int{1})
+	if first.Get(-1).(*glua.LUserData).Metatable == second.Get(-1).(*glua.LUserData).Metatable {
+		t.Fatal("independent states share a slice metatable")
+	}
+}
+
+func BenchmarkSlicePusher(b *testing.B) {
+	L := glua.NewState()
+	defer L.Close()
+	ips := []net.IP{net.ParseIP("127.0.0.1")}
+	pushIPs := NewSlicePusher[net.IP](L)
+	for _, benchmark := range []struct {
+		name string
+		push func(*glua.LState, []net.IP)
+	}{
+		{"bare", func(L *glua.LState, ips []net.IP) { PushUserData(L, ips) }},
+		{"luar", func(L *glua.LState, ips []net.IP) { L.Push(luar.New(L, ips)) }},
+		{"cached", pushIPs},
+	} {
+		b.Run(benchmark.name, func(b *testing.B) {
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				benchmark.push(L, ips)
+				L.Pop(1)
+			}
+		})
+	}
+}