Merge branch 'ethersphere-feature/ethutil-refactor' into develop

ethchain/dagger.go

@@ -3,6 +3,7 @@ package ethchain
 import (
 	"github.com/ethereum/eth-go/ethcrypto"
 	"github.com/ethereum/eth-go/ethlog"
+	"github.com/ethereum/eth-go/ethreact"
 	"github.com/ethereum/eth-go/ethutil"
 	"github.com/obscuren/sha3"
 	"hash"
@@ -14,7 +15,7 @@ import (
 var powlogger = ethlog.NewLogger("POW")
 
 type PoW interface {
-	Search(block *Block, reactChan chan ethutil.React) []byte
+	Search(block *Block, reactChan chan ethreact.Event) []byte
 	Verify(hash []byte, diff *big.Int, nonce []byte) bool
 	GetHashrate() int64
 }
@@ -28,7 +29,7 @@ func (pow *EasyPow) GetHashrate() int64 {
 	return pow.HashRate
 }
 
-func (pow *EasyPow) Search(block *Block, reactChan chan ethutil.React) []byte {
+func (pow *EasyPow) Search(block *Block, reactChan chan ethreact.Event) []byte {
 	r := rand.New(rand.NewSource(time.Now().UnixNano()))
 	hash := block.HashNoNonce()
 	diff := block.Difficulty

ethchain/state_manager.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"github.com/ethereum/eth-go/ethcrypto"
 	"github.com/ethereum/eth-go/ethlog"
+	"github.com/ethereum/eth-go/ethreact"
 	"github.com/ethereum/eth-go/ethstate"
 	"github.com/ethereum/eth-go/ethutil"
 	"github.com/ethereum/eth-go/ethwire"
@@ -36,7 +37,7 @@ type EthManager interface {
 	BlockChain() *BlockChain
 	TxPool() *TxPool
 	Broadcast(msgType ethwire.MsgType, data []interface{})
-	Reactor() *ethutil.ReactorEngine
+	Reactor() *ethreact.ReactorEngine
 	PeerCount() int
 	IsMining() bool
 	IsListening() bool

ethereum.go

@@ -14,6 +14,7 @@ import (
 	"github.com/ethereum/eth-go/ethchain"
 	"github.com/ethereum/eth-go/ethcrypto"
 	"github.com/ethereum/eth-go/ethlog"
+	"github.com/ethereum/eth-go/ethreact"
 	"github.com/ethereum/eth-go/ethrpc"
 	"github.com/ethereum/eth-go/ethutil"
 	"github.com/ethereum/eth-go/ethwire"
@@ -75,7 +76,7 @@ type Ethereum struct {
 
 	listening bool
 
-	reactor *ethutil.ReactorEngine
+	reactor *ethreact.ReactorEngine
 
 	RpcServer *ethrpc.JsonRpcServer
 
@@ -113,7 +114,7 @@ func New(db ethutil.Database, clientIdentity ethwire.ClientIdentity, keyManager
 		clientIdentity: clientIdentity,
 		isUpToDate:     true,
 	}
-	ethereum.reactor = ethutil.NewReactorEngine()
+	ethereum.reactor = ethreact.New()
 
 	ethereum.txPool = ethchain.NewTxPool(ethereum)
 	ethereum.blockChain = ethchain.NewBlockChain(ethereum)
@@ -125,7 +126,7 @@ func New(db ethutil.Database, clientIdentity ethwire.ClientIdentity, keyManager
 	return ethereum, nil
 }
 
-func (s *Ethereum) Reactor() *ethutil.ReactorEngine {
+func (s *Ethereum) Reactor() *ethreact.ReactorEngine {
 	return s.reactor
 }
 
@@ -357,6 +358,7 @@ func (s *Ethereum) ReapDeadPeerHandler() {
 
 // Start the ethereum
 func (s *Ethereum) Start(seed bool) {
+	s.reactor.Start()
 	// Bind to addr and port
 	ln, err := net.Listen("tcp", ":"+s.Port)
 	if err != nil {
@@ -456,6 +458,8 @@ func (s *Ethereum) Stop() {
 	}
 	s.txPool.Stop()
 	s.stateManager.Stop()
+	s.reactor.Flush()
+	s.reactor.Stop()
 
 	ethlogger.Infoln("Server stopped")
 	close(s.shutdownChan)

ethlog/loggers.go

@@ -39,7 +39,9 @@ func (msg *logMessage) send(logger LogSystem) {
 
 var logMessages chan (*logMessage)
 var logSystems []LogSystem
-var quit chan bool
+var quit chan chan error
+var drained chan bool
+var mutex = sync.Mutex{}
 
 type LogLevel uint8
 
@@ -52,34 +54,55 @@ const (
 	DebugDetailLevel
 )
 
+func dispatch(msg *logMessage) {
+	for _, logSystem := range logSystems {
+		if logSystem.GetLogLevel() >= msg.LogLevel {
+			msg.send(logSystem)
+		}
+	}
+}
+
 // log messages are dispatched to log writers
 func start() {
-out:
 	for {
 		select {
+		case status := <-quit:
+			status <- nil
+			return
 		case msg := <-logMessages:
-			for _, logSystem := range logSystems {
-				if logSystem.GetLogLevel() >= msg.LogLevel {
-					msg.send(logSystem)
-				}
-			}
-		case <-quit:
-			break out
+			dispatch(msg)
+		default:
+			drained <- true // this blocks until a message is sent to the queue
 		}
 	}
 }
 
-// waits until log messages are drained (dispatched to log writers)
-func Flush() {
-	quit <- true
+func send(msg *logMessage) {
+	logMessages <- msg
+	select {
+	case <-drained:
+	default:
+	}
+}
 
-done:
-	for {
+func Reset() {
+	mutex.Lock()
+	defer mutex.Unlock()
+	if logSystems != nil {
+		status := make(chan error)
+		quit <- status
 		select {
-		case <-logMessages:
+		case <-drained:
 		default:
-			break done
 		}
+		<-status
+	}
+}
+
+// waits until log messages are drained (dispatched to log writers)
+func Flush() {
+	if logSystems != nil {
+		<-drained
 	}
 }
 
@@ -97,7 +120,8 @@ func AddLogSystem(logSystem LogSystem) {
 	defer mutex.Unlock()
 	if logSystems == nil {
 		logMessages = make(chan *logMessage, 10)
-		quit = make(chan bool, 1)
+		quit = make(chan chan error, 1)
+		drained = make(chan bool, 1)
 		go start()
 	}
 	logSystems = append(logSystems, logSystem)
@@ -106,14 +130,14 @@ func AddLogSystem(logSystem LogSystem) {
 func (logger *Logger) sendln(level LogLevel, v ...interface{}) {
 	if logMessages != nil {
 		msg := newPrintlnLogMessage(level, logger.tag, v...)
-		logMessages <- msg
+		send(msg)
 	}
 }
 
 func (logger *Logger) sendf(level LogLevel, format string, v ...interface{}) {
 	if logMessages != nil {
 		msg := newPrintfLogMessage(level, logger.tag, format, v...)
-		logMessages <- msg
+		send(msg)
 	}
 }
 

ethlog/loggers_test.go

@@ -28,8 +28,19 @@ func (t *TestLogSystem) GetLogLevel() LogLevel {
 	return t.level
 }
 
-func quote(s string) string {
-	return fmt.Sprintf("'%s'", s)
+func TestLoggerFlush(t *testing.T) {
+	logger := NewLogger("TEST")
+	testLogSystem := &TestLogSystem{level: WarnLevel}
+	AddLogSystem(testLogSystem)
+	for i := 0; i < 5; i++ {
+		logger.Errorf(".")
+	}
+	Flush()
+	Reset()
+	output := testLogSystem.Output
+	if output != "[TEST] .[TEST] .[TEST] .[TEST] .[TEST] ." {
+		t.Error("Expected complete logger output '[TEST] .[TEST] .[TEST] .[TEST] .[TEST] .', got ", output)
+	}
 }
 
 func TestLoggerPrintln(t *testing.T) {
@@ -41,10 +52,11 @@ func TestLoggerPrintln(t *testing.T) {
 	logger.Infoln("info")
 	logger.Debugln("debug")
 	Flush()
+	Reset()
 	output := testLogSystem.Output
 	fmt.Println(quote(output))
 	if output != "[TEST] error\n[TEST] warn\n" {
-		t.Error("Expected logger output '[TEST] error\\n[TEST] warn\\n', got ", quote(testLogSystem.Output))
+		t.Error("Expected logger output '[TEST] error\\n[TEST] warn\\n', got ", output)
 	}
 }
 
@@ -57,10 +69,10 @@ func TestLoggerPrintf(t *testing.T) {
 	logger.Infof("info")
 	logger.Debugf("debug")
 	Flush()
+	Reset()
 	output := testLogSystem.Output
-	fmt.Println(quote(output))
 	if output != "[TEST] error to { 2}\n[TEST] warn" {
-		t.Error("Expected logger output '[TEST] error to { 2}\\n[TEST] warn', got ", quote(testLogSystem.Output))
+		t.Error("Expected logger output '[TEST] error to { 2}\\n[TEST] warn', got ", output)
 	}
 }
 
@@ -73,13 +85,14 @@ func TestMultipleLogSystems(t *testing.T) {
 	logger.Errorln("error")
 	logger.Warnln("warn")
 	Flush()
+	Reset()
 	output0 := testLogSystem0.Output
 	output1 := testLogSystem1.Output
 	if output0 != "[TEST] error\n" {
-		t.Error("Expected logger 0 output '[TEST] error\\n', got ", quote(testLogSystem0.Output))
+		t.Error("Expected logger 0 output '[TEST] error\\n', got ", output0)
 	}
 	if output1 != "[TEST] error\n[TEST] warn\n" {
-		t.Error("Expected logger 1 output '[TEST] error\\n[TEST] warn\\n', got ", quote(testLogSystem1.Output))
+		t.Error("Expected logger 1 output '[TEST] error\\n[TEST] warn\\n', got ", output1)
 	}
 }
 
@@ -94,9 +107,8 @@ func TestFileLogSystem(t *testing.T) {
 	Flush()
 	contents, _ := ioutil.ReadFile(filename)
 	output := string(contents)
-	fmt.Println(quote(output))
 	if output != "[TEST] error to test.log\n[TEST] warn\n" {
-		t.Error("Expected contents of file 'test.log': '[TEST] error to test.log\\n[TEST] warn\\n', got ", quote(output))
+		t.Error("Expected contents of file 'test.log': '[TEST] error to test.log\\n[TEST] warn\\n', got ", output)
 	} else {
 		os.Remove(filename)
 	}

ethminer/miner.go

@@ -4,7 +4,7 @@ import (
 	"bytes"
 	"github.com/ethereum/eth-go/ethchain"
 	"github.com/ethereum/eth-go/ethlog"
-	"github.com/ethereum/eth-go/ethutil"
+	"github.com/ethereum/eth-go/ethreact"
 	"github.com/ethereum/eth-go/ethwire"
 	"sort"
 )
@@ -15,13 +15,13 @@ type Miner struct {
 	pow         ethchain.PoW
 	ethereum    ethchain.EthManager
 	coinbase    []byte
-	reactChan   chan ethutil.React
+	reactChan   chan ethreact.Event
 	txs         ethchain.Transactions
 	uncles      []*ethchain.Block
 	block       *ethchain.Block
 	powChan     chan []byte
-	powQuitChan chan ethutil.React
-	quitChan    chan bool
+	powQuitChan chan ethreact.Event
+	quitChan    chan chan error
 }
 
 func (self *Miner) GetPow() ethchain.PoW {
@@ -29,55 +29,53 @@ func (self *Miner) GetPow() ethchain.PoW {
 }
 
 func NewDefaultMiner(coinbase []byte, ethereum ethchain.EthManager) *Miner {
-	reactChan := make(chan ethutil.React, 1)   // This is the channel that receives 'updates' when ever a new transaction or block comes in
-	powChan := make(chan []byte, 1)            // This is the channel that receives valid sha hases for a given block
-	powQuitChan := make(chan ethutil.React, 1) // This is the channel that can exit the miner thread
-	quitChan := make(chan bool, 1)
-
-	ethereum.Reactor().Subscribe("newBlock", reactChan)
-	ethereum.Reactor().Subscribe("newTx:pre", reactChan)
-
-	// We need the quit chan to be a Reactor event.
-	// The POW search method is actually blocking and if we don't
-	// listen to the reactor events inside of the pow itself
-	// The miner overseer will never get the reactor events themselves
-	// Only after the miner will find the sha
-	ethereum.Reactor().Subscribe("newBlock", powQuitChan)
-	ethereum.Reactor().Subscribe("newTx:pre", powQuitChan)
-
 	miner := Miner{
-		pow:         &ethchain.EasyPow{},
-		ethereum:    ethereum,
-		coinbase:    coinbase,
-		reactChan:   reactChan,
-		powChan:     powChan,
-		powQuitChan: powQuitChan,
-		quitChan:    quitChan,
+		pow:      &ethchain.EasyPow{},
+		ethereum: ethereum,
+		coinbase: coinbase,
 	}
 
-	// Insert initial TXs in our little miner 'pool'
-	miner.txs = ethereum.TxPool().Flush()
-	miner.block = ethereum.BlockChain().NewBlock(miner.coinbase)
-
 	return &miner
 }
 
 func (miner *Miner) Start() {
+	miner.reactChan = make(chan ethreact.Event, 1)   // This is the channel that receives 'updates' when ever a new transaction or block comes in
+	miner.powChan = make(chan []byte, 1)             // This is the channel that receives valid sha hashes for a given block
+	miner.powQuitChan = make(chan ethreact.Event, 1) // This is the channel that can exit the miner thread
+	miner.quitChan = make(chan chan error, 1)
+
+	// Insert initial TXs in our little miner 'pool'
+	miner.txs = miner.ethereum.TxPool().Flush()
+	miner.block = miner.ethereum.BlockChain().NewBlock(miner.coinbase)
+
 	// Prepare inital block
 	//miner.ethereum.StateManager().Prepare(miner.block.State(), miner.block.State())
 	go miner.listener()
+
+	reactor := miner.ethereum.Reactor()
+	reactor.Subscribe("newBlock", miner.reactChan)
+	reactor.Subscribe("newTx:pre", miner.reactChan)
+
+	// We need the quit chan to be a Reactor event.
+	// The POW search method is actually blocking and if we don't
+	// listen to the reactor events inside of the pow itself
+	// The miner overseer will never get the reactor events themselves
+	// Only after the miner will find the sha
+	reactor.Subscribe("newBlock", miner.powQuitChan)
+	reactor.Subscribe("newTx:pre", miner.powQuitChan)
+
 	logger.Infoln("Started")
 
-	miner.ethereum.Reactor().Post("miner:start", miner)
+	reactor.Post("miner:start", miner)
 }
 
 func (miner *Miner) listener() {
-out:
 	for {
 		select {
-		case <-miner.quitChan:
+		case status := <-miner.quitChan:
 			logger.Infoln("Stopped")
-			break out
+			status <- nil
+			return
 		case chanMessage := <-miner.reactChan:
 
 			if block, ok := chanMessage.Resource.(*ethchain.Block); ok {
@@ -133,13 +131,22 @@ out:
 	}
 }
 
-func (self *Miner) Stop() {
+func (miner *Miner) Stop() {
 	logger.Infoln("Stopping...")
 
-	self.quitChan <- true
-	self.powQuitChan <- ethutil.React{}
+	miner.powQuitChan <- ethreact.Event{}
+
+	status := make(chan error)
+	miner.quitChan <- status
+	<-status
+
+	reactor := miner.ethereum.Reactor()
+	reactor.Unsubscribe("newBlock", miner.powQuitChan)
+	reactor.Unsubscribe("newTx:pre", miner.powQuitChan)
+	reactor.Unsubscribe("newBlock", miner.reactChan)
+	reactor.Unsubscribe("newTx:pre", miner.reactChan)
 
-	self.ethereum.Reactor().Post("miner:stop", self)
+	reactor.Post("miner:stop", miner)
 }
 
 func (self *Miner) mineNewBlock() {

ethreact/README.md

+## Reactor
+
+Reactor is the internal broadcast engine that allows components to be notified of ethereum stack events such as finding new blocks or change in state.
+Event notification is handled via subscription:
+
+    var blockChan = make(chan ethreact.Event, 10)
+    reactor.Subscribe("newBlock", blockChan)
+
+ethreact.Event broadcast on the channel are 
+
+    type Event struct {
+        Resource interface{}
+        Name     string
+    } 
+
+Resource is polimorphic depending on the event type and should be typecast before use, e.g:
+
+    b := <-blockChan:
+    block := b.Resource.(*ethchain.Block)
+
+Events are guaranteed to be broadcast in order but the broadcast never blocks or leaks which means while the subscribing event channel is blocked (e.g., full if buffered) further messages will be skipped. 
+
+The engine allows arbitrary events to be posted and subscribed to. 
+
+    ethereum.Reactor().Post("newBlock", newBlock)
+
+
+    
\ No newline at end of file

ethreact/reactor.go

+package ethreact
+
+import (
+	"github.com/ethereum/eth-go/ethlog"
+	"sync"
+)
+
+var logger = ethlog.NewLogger("REACTOR")
+
+const (
+	eventBufferSize int = 10
+)
+
+type EventHandler struct {
+	lock  sync.RWMutex
+	name  string
+	chans []chan Event
+}
+
+// Post the Event with the reactor resource on the channels
+// currently subscribed to the event
+func (e *EventHandler) Post(event Event) {
+	e.lock.RLock()
+	defer e.lock.RUnlock()
+
+	// if we want to preserve order pushing to subscibed channels
+	// dispatching should be syncrounous
+	// this means if subscribed event channel is blocked
+	// the reactor dispatch will be blocked, so we need to mitigate by skipping
+	// rogue blocking subscribers
+	for i, ch := range e.chans {
+		select {
+		case ch <- event:
+		default:
+			logger.Warnf("subscribing channel %d to event %s blocked. skipping\n", i, event.Name)
+		}
+	}
+}
+
+// Add a subscriber to this event
+func (e *EventHandler) Add(ch chan Event) {
+	e.lock.Lock()
+	defer e.lock.Unlock()
+
+	e.chans = append(e.chans, ch)
+}
+
+// Remove a subscriber
+func (e *EventHandler) Remove(ch chan Event) int {
+	e.lock.Lock()
+	defer e.lock.Unlock()
+
+	for i, c := range e.chans {
+		if c == ch {
+			e.chans = append(e.chans[:i], e.chans[i+1:]...)
+		}
+	}
+	return len(e.chans)
+}
+
+// Basic reactor event
+type Event struct {
+	Resource interface{}
+	Name     string
+}
+
+// The reactor basic engine. Acts as bridge
+// between the events and the subscribers/posters
+type ReactorEngine struct {
+	lock          sync.RWMutex
+	eventChannel  chan Event
+	eventHandlers map[string]*EventHandler
+	quit          chan chan error
+	running       bool
+	drained       chan bool
+}
+
+func New() *ReactorEngine {
+	return &ReactorEngine{
+		eventHandlers: make(map[string]*EventHandler),
+		eventChannel:  make(chan Event, eventBufferSize),
+		quit:          make(chan chan error, 1),
+		drained:       make(chan bool, 1),
+	}
+}
+
+func (reactor *ReactorEngine) Start() {
+	reactor.lock.Lock()
+	defer reactor.lock.Unlock()
+	if !reactor.running {
+		go func() {
+			for {
+				select {
+				case status := <-reactor.quit:
+					reactor.lock.Lock()
+					defer reactor.lock.Unlock()
+					reactor.running = false
+					logger.Infoln("stopped")
+					status <- nil
+					return
+				case event := <-reactor.eventChannel:
+					// needs to be called syncronously to keep order of events
+					reactor.dispatch(event)
+				default:
+					reactor.drained <- true // blocking till message is coming in
+				}
+			}
+		}()
+		reactor.running = true
+		logger.Infoln("started")
+	}
+}
+
+func (reactor *ReactorEngine) Stop() {
+	if reactor.running {
+		status := make(chan error)
+		reactor.quit <- status
+		select {
+		case <-reactor.drained:
+		default:
+		}
+		<-status
+	}
+}
+
+func (reactor *ReactorEngine) Flush() {
+	<-reactor.drained
+}
+
+// Subscribe a channel to the specified event
+func (reactor *ReactorEngine) Subscribe(event string, eventChannel chan Event) {
+	reactor.lock.Lock()
+	defer reactor.lock.Unlock()
+
+	eventHandler := reactor.eventHandlers[event]
+	// Create a new event handler if one isn't available
+	if eventHandler == nil {
+		eventHandler = &EventHandler{name: event}
+		reactor.eventHandlers[event] = eventHandler
+	}
+	// Add the events channel to reactor event handler
+	eventHandler.Add(eventChannel)
+	logger.Debugf("added new subscription to %s", event)
+}
+
+func (reactor *ReactorEngine) Unsubscribe(event string, eventChannel chan Event) {
+	reactor.lock.Lock()
+	defer reactor.lock.Unlock()
+
+	eventHandler := reactor.eventHandlers[event]
+	if eventHandler != nil {
+		len := eventHandler.Remove(eventChannel)
+		if len == 0 {
+			reactor.eventHandlers[event] = nil
+		}
+		logger.Debugf("removed subscription to %s", event)
+	}
+}
+
+func (reactor *ReactorEngine) Post(event string, resource interface{}) {
+	reactor.lock.Lock()
+	defer reactor.lock.Unlock()
+
+	if reactor.running {
+		reactor.eventChannel <- Event{Resource: resource, Name: event}
+		select {
+		case <-reactor.drained:
+		default:
+		}
+	}
+}
+
+func (reactor *ReactorEngine) dispatch(event Event) {
+	name := event.Name
+	eventHandler := reactor.eventHandlers[name]
+	// if no subscriptions to this event type - no event handler created
+	// then noone to notify
+	if eventHandler != nil {
+		// needs to be called syncronously
+		eventHandler.Post(event)
+	}
+}

ethreact/reactor_test.go

+package ethreact
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestReactorAdd(t *testing.T) {
+	reactor := New()
+	ch := make(chan Event)
+	reactor.Subscribe("test", ch)
+	if reactor.eventHandlers["test"] == nil {
+		t.Error("Expected new eventHandler to be created")
+	}
+	reactor.Unsubscribe("test", ch)
+	if reactor.eventHandlers["test"] != nil {
+		t.Error("Expected eventHandler to be removed")
+	}
+}
+
+func TestReactorEvent(t *testing.T) {
+	var name string
+	reactor := New()
+	// Buffer the channel, so it doesn't block for this test
+	cap := 20
+	ch := make(chan Event, cap)
+	reactor.Subscribe("even", ch)
+	reactor.Subscribe("odd", ch)
+	reactor.Post("even", "disappears") // should not broadcast if engine not started
+	reactor.Start()
+	for i := 0; i < cap; i++ {
+		if i%2 == 0 {
+			name = "even"
+		} else {
+			name = "odd"
+		}
+		reactor.Post(name, i)
+	}
+	reactor.Post("test", cap) // this should not block
+	i := 0
+	reactor.Flush()
+	close(ch)
+	for event := range ch {
+		fmt.Printf("%d: %v", i, event)
+		if i%2 == 0 {
+			name = "even"
+		} else {
+			name = "odd"
+		}
+		if val, ok := event.Resource.(int); ok {
+			if i != val || event.Name != name {
+				t.Error("Expected event %d to be of type %s and resource %d, got ", i, name, i, val)
+			}
+		} else {
+			t.Error("Unable to cast")
+		}
+		i++
+	}
+	if i != cap {
+		t.Error("excpected exactly %d events, got ", i)
+	}
+	reactor.Stop()
+}

ethutil/reactor.go

-package ethutil
-
-import (
-	"sync"
-)
-
-type ReactorEvent struct {
-	mut   sync.Mutex
-	event string
-	chans []chan React
-}
-
-// Post the specified reactor resource on the channels
-// currently subscribed
-func (e *ReactorEvent) Post(react React) {
-	e.mut.Lock()
-	defer e.mut.Unlock()
-
-	for _, ch := range e.chans {
-		go func(ch chan React) {
-			ch <- react
-		}(ch)
-	}
-}
-
-// Add a subscriber to this event
-func (e *ReactorEvent) Add(ch chan React) {
-	e.mut.Lock()
-	defer e.mut.Unlock()
-
-	e.chans = append(e.chans, ch)
-}
-
-// Remove a subscriber
-func (e *ReactorEvent) Remove(ch chan React) {
-	e.mut.Lock()
-	defer e.mut.Unlock()
-
-	for i, c := range e.chans {
-		if c == ch {
-			e.chans = append(e.chans[:i], e.chans[i+1:]...)
-		}
-	}
-}
-
-// Basic reactor resource
-type React struct {
-	Resource interface{}
-	Event    string
-}
-
-// The reactor basic engine. Acts as bridge
-// between the events and the subscribers/posters
-type ReactorEngine struct {
-	patterns map[string]*ReactorEvent
-}
-
-func NewReactorEngine() *ReactorEngine {
-	return &ReactorEngine{patterns: make(map[string]*ReactorEvent)}
-}
-
-// Subscribe a channel to the specified event
-func (reactor *ReactorEngine) Subscribe(event string, ch chan React) {
-	ev := reactor.patterns[event]
-	// Create a new event if one isn't available
-	if ev == nil {
-		ev = &ReactorEvent{event: event}
-		reactor.patterns[event] = ev
-	}
-
-	// Add the channel to reactor event handler
-	ev.Add(ch)
-}
-
-func (reactor *ReactorEngine) Unsubscribe(event string, ch chan React) {
-	ev := reactor.patterns[event]
-	if ev != nil {
-		ev.Remove(ch)
-	}
-}
-
-func (reactor *ReactorEngine) Post(event string, resource interface{}) {
-	ev := reactor.patterns[event]
-	if ev != nil {
-		ev.Post(React{Resource: resource, Event: event})
-	}
-}

ethutil/reactor_test.go

-package ethutil
-
-import "testing"
-
-func TestReactorAdd(t *testing.T) {
-	engine := NewReactorEngine()
-	ch := make(chan React)
-	engine.Subscribe("test", ch)
-	if len(engine.patterns) != 1 {
-		t.Error("Expected patterns to be 1, got", len(engine.patterns))
-	}
-}
-
-func TestReactorEvent(t *testing.T) {
-	engine := NewReactorEngine()
-
-	// Buffer 1, so it doesn't block for this test
-	ch := make(chan React, 1)
-	engine.Subscribe("test", ch)
-	engine.Post("test", "hello")
-
-	value := <-ch
-	if val, ok := value.Resource.(string); ok {
-		if val != "hello" {
-			t.Error("Expected Resource to be 'hello', got", val)
-		}
-	} else {
-		t.Error("Unable to cast")
-	}
-}