MPH domian matcher: Support building & using cache directly (instead of building from geosite.dat when Xray starts) (#5505)

Like https://github.com/XTLS/Xray-core/pull/5488#issuecomment-3710995080

app/router/geosite_compact.go

@@ -0,0 +1,100 @@
+package router
+
+import (
+	"encoding/gob"
+	"errors"
+	"io"
+	"runtime"
+
+	"github.com/xtls/xray-core/common/strmatcher"
+)
+
+type geoSiteListGob struct {
+	Sites map[string][]byte
+	Deps  map[string][]string
+	Hosts map[string][]string
+}
+
+func SerializeGeoSiteList(sites []*GeoSite, deps map[string][]string, hosts map[string][]string, w io.Writer) error {
+	data := geoSiteListGob{
+		Sites: make(map[string][]byte),
+		Deps:  deps,
+		Hosts: hosts,
+	}
+
+	for _, site := range sites {
+		if site == nil {
+			continue
+		}
+		var buf bytesWriter
+		if err := SerializeDomainMatcher(site.Domain, &buf); err != nil {
+			return err
+		}
+		data.Sites[site.CountryCode] = buf.Bytes()
+	}
+
+	return gob.NewEncoder(w).Encode(data)
+}
+
+type bytesWriter struct {
+	data []byte
+}
+
+func (w *bytesWriter) Write(p []byte) (n int, err error) {
+	w.data = append(w.data, p...)
+	return len(p), nil
+}
+
+func (w *bytesWriter) Bytes() []byte {
+	return w.data
+}
+
+func LoadGeoSiteMatcher(r io.Reader, countryCode string) (strmatcher.IndexMatcher, error) {
+	var data geoSiteListGob
+	if err := gob.NewDecoder(r).Decode(&data); err != nil {
+		return nil, err
+	}
+
+	return loadWithDeps(&data, countryCode, make(map[string]bool))
+}
+
+func loadWithDeps(data *geoSiteListGob, code string, visited map[string]bool) (strmatcher.IndexMatcher, error) {
+	if visited[code] {
+		return nil, errors.New("cyclic dependency")
+	}
+	visited[code] = true
+
+	var matchers []strmatcher.IndexMatcher
+
+	if siteData, ok := data.Sites[code]; ok {
+		m, err := NewDomainMatcherFromBuffer(siteData)
+		if err == nil {
+			matchers = append(matchers, m)
+		}
+	}
+
+	if deps, ok := data.Deps[code]; ok {
+		for _, dep := range deps {
+			m, err := loadWithDeps(data, dep, visited)
+			if err == nil {
+				matchers = append(matchers, m)
+			}
+		}
+	}
+
+	if len(matchers) == 0 {
+		return nil, errors.New("matcher not found for: " + code)
+	}
+	if len(matchers) == 1 {
+		return matchers[0], nil
+	}
+	runtime.GC()
+	return &strmatcher.IndexMatcherGroup{Matchers: matchers}, nil
+}
+func LoadGeoSiteHosts(r io.Reader) (map[string][]string, error) {
+	var data geoSiteListGob
+	if err := gob.NewDecoder(r).Decode(&data); err != nil {
+		return nil, err
+	}
+	return data.Hosts, nil
+}