TUN-1968: Gracefully diff StreamHandler.UpdateConfig

tunnelhostnamemapper/tunnelhostnamemapper.go

@@ -5,6 +5,7 @@ import (
 
 	"github.com/cloudflare/cloudflared/h2mux"
 	"github.com/cloudflare/cloudflared/originservice"
+	"github.com/cloudflare/cloudflared/tunnelrpc/pogs"
 )
 
 // TunnelHostnameMapper maps TunnelHostname to an OriginService
@@ -38,12 +39,55 @@ func (om *TunnelHostnameMapper) Add(key h2mux.TunnelHostname, os originservice.O
 	om.tunnelHostnameToOrigin[key] = os
 }
 
-// DeleteAll mappings, and shutdown all OriginService
-func (om *TunnelHostnameMapper) DeleteAll() {
+// Delete a mapping, and shutdown its OriginService
+func (om *TunnelHostnameMapper) Delete(key h2mux.TunnelHostname) (keyFound bool) {
 	om.Lock()
 	defer om.Unlock()
-	for key, os := range om.tunnelHostnameToOrigin {
+	if os, ok := om.tunnelHostnameToOrigin[key]; ok {
 		os.Shutdown()
 		delete(om.tunnelHostnameToOrigin, key)
+		return true
 	}
+	return false
+}
+
+// ToRemove finds all keys that should be removed from the TunnelHostnameMapper.
+func (om *TunnelHostnameMapper) ToRemove(newConfigs []*pogs.ReverseProxyConfig) (toRemove []h2mux.TunnelHostname) {
+	om.Lock()
+	defer om.Unlock()
+
+	// Convert into a set, for O(1) lookups instead of O(n)
+	newConfigSet := toSet(newConfigs)
+
+	// If a config in `om` isn't in `newConfigs`, it must be removed.
+	for hostname := range om.tunnelHostnameToOrigin {
+		if _, ok := newConfigSet[hostname]; !ok {
+			toRemove = append(toRemove, hostname)
+		}
+	}
+
+	return
+}
+
+// ToAdd filters the given configs, keeping those that should be added to the TunnelHostnameMapper.
+func (om *TunnelHostnameMapper) ToAdd(newConfigs []*pogs.ReverseProxyConfig) (toAdd []*pogs.ReverseProxyConfig) {
+	om.Lock()
+	defer om.Unlock()
+
+	// If a config in `newConfigs` isn't in `om`, it must be added.
+	for _, config := range newConfigs {
+		if _, ok := om.tunnelHostnameToOrigin[config.TunnelHostname]; !ok {
+			toAdd = append(toAdd, config)
+		}
+	}
+
+	return
+}
+
+func toSet(configs []*pogs.ReverseProxyConfig) map[h2mux.TunnelHostname]*pogs.ReverseProxyConfig {
+	m := make(map[h2mux.TunnelHostname]*pogs.ReverseProxyConfig)
+	for _, config := range configs {
+		m[config.TunnelHostname] = config
+	}
+	return m
 }