Merge pull request #1970 from karalabe/customizable-protocol-stacks

Customizable protocol stacks

1 files changed, 266 insertions, 0 deletions

diff --git a/node/node.go b/node/node.go
new file mode 100644
index 000000000..5566bc44b
--- /dev/null
+++ b/node/node.go
@@ -0,0 +1,266 @@
+// 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 represents the Ethereum protocol stack container.
+package node
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"reflect"
+	"sync"
+	"syscall"
+
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/p2p"
+)
+
+var (
+	ErrDatadirUsed    = errors.New("datadir already used")
+	ErrNodeStopped    = errors.New("node not started")
+	ErrNodeRunning    = errors.New("node already running")
+	ErrServiceUnknown = errors.New("unknown service")
+
+	datadirInUseErrnos = map[uint]bool{11: true, 32: true, 35: true}
+)
+
+// Node represents a P2P node into which arbitrary (uniquely typed) services might
+// be registered.
+type Node struct {
+	datadir  string         // Path to the currently used data directory
+	eventmux *event.TypeMux // Event multiplexer used between the services of a stack
+
+	serverConfig *p2p.Server // Configuration of the underlying P2P networking layer
+	server       *p2p.Server // Currently running P2P networking layer
+
+	serviceFuncs []ServiceConstructor     // Service constructors (in dependency order)
+	services     map[reflect.Type]Service // Currently running services
+
+	stop chan struct{} // Channel to wait for termination notifications
+	lock sync.RWMutex
+}
+
+// New creates a new P2P node, ready for protocol registration.
+func New(conf *Config) (*Node, error) {
+	// Ensure the data directory exists, failing if it cannot be created
+	if conf.DataDir != "" {
+		if err := os.MkdirAll(conf.DataDir, 0700); err != nil {
+			return nil, err
+		}
+	}
+	// Assemble the networking layer and the node itself
+	nodeDbPath := ""
+	if conf.DataDir != "" {
+		nodeDbPath = filepath.Join(conf.DataDir, datadirNodeDatabase)
+	}
+	return &Node{
+		datadir: conf.DataDir,
+		serverConfig: &p2p.Server{
+			PrivateKey:      conf.NodeKey(),
+			Name:            conf.Name,
+			Discovery:       !conf.NoDiscovery,
+			BootstrapNodes:  conf.BootstrapNodes,
+			StaticNodes:     conf.StaticNodes(),
+			TrustedNodes:    conf.TrusterNodes(),
+			NodeDatabase:    nodeDbPath,
+			ListenAddr:      conf.ListenAddr,
+			NAT:             conf.NAT,
+			Dialer:          conf.Dialer,
+			NoDial:          conf.NoDial,
+			MaxPeers:        conf.MaxPeers,
+			MaxPendingPeers: conf.MaxPendingPeers,
+		},
+		serviceFuncs: []ServiceConstructor{},
+		eventmux:     new(event.TypeMux),
+	}, nil
+}
+
+// Register injects a new service into the node's stack. The service created by
+// the passed constructor must be unique in its type with regard to sibling ones.
+func (n *Node) Register(constructor ServiceConstructor) error {
+	n.lock.Lock()
+	defer n.lock.Unlock()
+
+	if n.server != nil {
+		return ErrNodeRunning
+	}
+	n.serviceFuncs = append(n.serviceFuncs, constructor)
+	return nil
+}
+
+// Start create a live P2P node and starts running it.
+func (n *Node) Start() error {
+	n.lock.Lock()
+	defer n.lock.Unlock()
+
+	// Short circuit if the node's already running
+	if n.server != nil {
+		return ErrNodeRunning
+	}
+	// Otherwise copy and specialize the P2P configuration
+	running := new(p2p.Server)
+	*running = *n.serverConfig
+
+	services := make(map[reflect.Type]Service)
+	for _, constructor := range n.serviceFuncs {
+		// Create a new context for the particular service
+		ctx := &ServiceContext{
+			datadir:  n.datadir,
+			services: make(map[reflect.Type]Service),
+			EventMux: n.eventmux,
+		}
+		for kind, s := range services { // copy needed for threaded access
+			ctx.services[kind] = s
+		}
+		// Construct and save the service
+		service, err := constructor(ctx)
+		if err != nil {
+			return err
+		}
+		kind := reflect.TypeOf(service)
+		if _, exists := services[kind]; exists {
+			return &DuplicateServiceError{Kind: kind}
+		}
+		services[kind] = service
+	}
+	// Gather the protocols and start the freshly assembled P2P server
+	for _, service := range services {
+		running.Protocols = append(running.Protocols, service.Protocols()...)
+	}
+	if err := running.Start(); err != nil {
+		if errno, ok := err.(syscall.Errno); ok && datadirInUseErrnos[uint(errno)] {
+			return ErrDatadirUsed
+		}
+		return err
+	}
+	// Start each of the services
+	started := []reflect.Type{}
+	for kind, service := range services {
+		// Start the next service, stopping all previous upon failure
+		if err := service.Start(running); err != nil {
+			for _, kind := range started {
+				services[kind].Stop()
+			}
+			running.Stop()
+
+			return err
+		}
+		// Mark the service started for potential cleanup
+		started = append(started, kind)
+	}
+	// Finish initializing the startup
+	n.services = services
+	n.server = running
+	n.stop = make(chan struct{})
+
+	return nil
+}
+
+// Stop terminates a running node along with all it's services. In the node was
+// not started, an error is returned.
+func (n *Node) Stop() error {
+	n.lock.Lock()
+	defer n.lock.Unlock()
+
+	// Short circuit if the node's not running
+	if n.server == nil {
+		return ErrNodeStopped
+	}
+	// Otherwise terminate all the services and the P2P server too
+	failure := &StopError{
+		Services: make(map[reflect.Type]error),
+	}
+	for kind, service := range n.services {
+		if err := service.Stop(); err != nil {
+			failure.Services[kind] = err
+		}
+	}
+	n.server.Stop()
+
+	n.services = nil
+	n.server = nil
+	close(n.stop)
+
+	if len(failure.Services) > 0 {
+		return failure
+	}
+	return nil
+}
+
+// Wait blocks the thread until the node is stopped. If the node is not running
+// at the time of invocation, the method immediately returns.
+func (n *Node) Wait() {
+	n.lock.RLock()
+	if n.server == nil {
+		return
+	}
+	stop := n.stop
+	n.lock.RUnlock()
+
+	<-stop
+}
+
+// Restart terminates a running node and boots up a new one in its place. If the
+// node isn't running, an error is returned.
+func (n *Node) Restart() error {
+	if err := n.Stop(); err != nil {
+		return err
+	}
+	if err := n.Start(); err != nil {
+		return err
+	}
+	return nil
+}
+
+// Server retrieves the currently running P2P network layer. This method is meant
+// only to inspect fields of the currently running server, life cycle management
+// should be left to this Node entity.
+func (n *Node) Server() *p2p.Server {
+	n.lock.RLock()
+	defer n.lock.RUnlock()
+
+	return n.server
+}
+
+// Service retrieves a currently running service registered of a specific type.
+func (n *Node) Service(service interface{}) error {
+	n.lock.RLock()
+	defer n.lock.RUnlock()
+
+	// Short circuit if the node's not running
+	if n.server == nil {
+		return ErrNodeStopped
+	}
+	// Otherwise try to find the service to return
+	element := reflect.ValueOf(service).Elem()
+	if running, ok := n.services[element.Type()]; ok {
+		element.Set(reflect.ValueOf(running))
+		return nil
+	}
+	return ErrServiceUnknown
+}
+
+// DataDir retrieves the current datadir used by the protocol stack.
+func (n *Node) DataDir() string {
+	return n.datadir
+}
+
+// EventMux retrieves the event multiplexer used by all the network services in
+// the current protocol stack.
+func (n *Node) EventMux() *event.TypeMux {
+	return n.eventmux
+}