cmd, common, core, eth, node, rpc, tests, whisper, xeth: use protocol stacks

node/service.go

@@ -18,6 +18,7 @@ package node
 
 import (
 	"path/filepath"
+	"reflect"
 
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
@@ -28,18 +29,39 @@ import (
 // the protocol stack, that is passed to all constructors to be optionally used;
 // as well as utility methods to operate on the service environment.
 type ServiceContext struct {
-	dataDir  string         // Data directory for protocol persistence
-	EventMux *event.TypeMux // Event multiplexer used for decoupled notifications
+	datadir  string             // Data directory for protocol persistence
+	services map[string]Service // Index of the already constructed services
+	EventMux *event.TypeMux     // Event multiplexer used for decoupled notifications
 }
 
 // Database opens an existing database with the given name (or creates one if no
 // previous can be found) from within the node's data directory. If the node is
 // an ephemeral one, a memory database is returned.
 func (ctx *ServiceContext) Database(name string, cache int) (ethdb.Database, error) {
-	if ctx.dataDir == "" {
+	if ctx.datadir == "" {
 		return ethdb.NewMemDatabase()
 	}
-	return ethdb.NewLDBDatabase(filepath.Join(ctx.dataDir, name), cache)
+	return ethdb.NewLDBDatabase(filepath.Join(ctx.datadir, name), cache)
+}
+
+// Service retrieves an already constructed service registered under a given id.
+func (ctx *ServiceContext) Service(id string) Service {
+	return ctx.services[id]
+}
+
+// SingletonService retrieves an already constructed service using a specific type
+// implementing the Service interface. This is a utility function for scenarios
+// where it is known that only one instance of a given service type is running,
+// allowing to access services without needing to know their specific id with
+// which they were registered.
+func (ctx *ServiceContext) SingletonService(service interface{}) (string, error) {
+	for id, running := range ctx.services {
+		if reflect.TypeOf(running) == reflect.ValueOf(service).Elem().Type() {
+			reflect.ValueOf(service).Elem().Set(reflect.ValueOf(running))
+			return id, nil
+		}
+	}
+	return "", ErrServiceUnknown
 }
 
 // ServiceConstructor is the function signature of the constructors needed to be
@@ -58,8 +80,9 @@ type Service interface {
 	// Protocol retrieves the P2P protocols the service wishes to start.
 	Protocols() []p2p.Protocol
 
-	// Start spawns any goroutines required by the service.
-	Start() error
+	// Start is called after all services have been constructed and the networking
+	// layer was also initialized to spawn any goroutines required by the service.
+	Start(server *p2p.Server) error
 
 	// Stop terminates all goroutines belonging to the service, blocking until they
 	// are all terminated.