1 files changed, 131 insertions, 0 deletions
diff --git a/node/service.go b/node/service.go
new file mode 100644
index 0000000..fd03a57
--- /dev/null
+++ b/node/service.go
@@ -0,0 +1,131 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package node
+
+import (
+	"path/filepath"
+	"reflect"
+
+	"github.com/ethereum/go-ethereum/accounts"
+	"github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/p2p"
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+// ServiceContext is a collection of service independent options inherited from
+// 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 {
+	config         *Config
+	services       map[reflect.Type]Service // Index of the already constructed services
+	EventMux       *event.TypeMux           // Event multiplexer used for decoupled notifications
+	AccountManager *accounts.Manager        // Account manager created by the node.
+}
+
+// OpenDatabase 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) OpenDatabase(name string, cache int, handles int, namespace string) (ethdb.Database, error) {
+	if ctx.config.DataDir == "" {
+		return rawdb.NewMemoryDatabase(), nil
+	}
+	return rawdb.NewLevelDBDatabase(ctx.config.ResolvePath(name), cache, handles, namespace)
+}
+
+// OpenDatabaseWithFreezer opens an existing database with the given name (or
+// creates one if no previous can be found) from within the node's data directory,
+// also attaching a chain freezer to it that moves ancient chain data from the
+// database to immutable append-only files. If the node is an ephemeral one, a
+// memory database is returned.
+func (ctx *ServiceContext) OpenDatabaseWithFreezer(name string, cache int, handles int, freezer string, namespace string) (ethdb.Database, error) {
+	if ctx.config.DataDir == "" {
+		return rawdb.NewMemoryDatabase(), nil
+	}
+	root := ctx.config.ResolvePath(name)
+
+	switch {
+	case freezer == "":
+		freezer = filepath.Join(root, "ancient")
+	case !filepath.IsAbs(freezer):
+		freezer = ctx.config.ResolvePath(freezer)
+	}
+	return rawdb.NewLevelDBDatabaseWithFreezer(root, cache, handles, freezer, namespace)
+}
+
+// ResolvePath resolves a user path into the data directory if that was relative
+// and if the user actually uses persistent storage. It will return an empty string
+// for emphemeral storage and the user's own input for absolute paths.
+func (ctx *ServiceContext) ResolvePath(path string) string {
+	return ctx.config.ResolvePath(path)
+}
+
+// Service retrieves a currently running service registered of a specific type.
+func (ctx *ServiceContext) Service(service interface{}) error {
+	element := reflect.ValueOf(service).Elem()
+	if running, ok := ctx.services[element.Type()]; ok {
+		element.Set(reflect.ValueOf(running))
+		return nil
+	}
+	return ErrServiceUnknown
+}
+
+// ExtRPCEnabled returns the indicator whether node enables the external
+// RPC(http, ws or graphql).
+func (ctx *ServiceContext) ExtRPCEnabled() bool {
+	return ctx.config.ExtRPCEnabled()
+}
+
+func NewServiceContext(mux *event.TypeMux) ServiceContext {
+    return ServiceContext {
+        config: nil,
+        services: make(map[reflect.Type]Service),
+        EventMux: mux,
+        AccountManager: nil,
+    }
+}
+
+// ServiceConstructor is the function signature of the constructors needed to be
+// registered for service instantiation.
+type ServiceConstructor func(ctx *ServiceContext) (Service, error)
+
+// Service is an individual protocol that can be registered into a node.
+//
+// Notes:
+//
+// • Service life-cycle management is delegated to the node. The service is allowed to
+// initialize itself upon creation, but no goroutines should be spun up outside of the
+// Start method.
+//
+// • Restart logic is not required as the node will create a fresh instance
+// every time a service is started.
+type Service interface {
+	// Protocols retrieves the P2P protocols the service wishes to start.
+	Protocols() []p2p.Protocol
+
+	// APIs retrieves the list of RPC descriptors the service provides
+	APIs() []rpc.API
+
+	// 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.
+	Stop() error
+}