rpc: add pub/sub support

eth/api.go

@@ -28,6 +28,8 @@ import (
 	"sync"
 	"time"
 
+	"golang.org/x/net/context"
+
 	"github.com/ethereum/ethash"
 	"github.com/ethereum/go-ethereum/accounts"
 	"github.com/ethereum/go-ethereum/common"
@@ -457,16 +459,46 @@ func (s *PrivateAccountAPI) LockAccount(addr common.Address) bool {
 // It offers only methods that operate on public data that is freely available to anyone.
 type PublicBlockChainAPI struct {
 	config   *core.ChainConfig
-	bc       *core.BlockChain
-	chainDb  ethdb.Database
-	eventMux *event.TypeMux
-	am       *accounts.Manager
-	miner    *miner.Miner
+	bc                      *core.BlockChain
+	chainDb                 ethdb.Database
+	eventMux                *event.TypeMux
+	muNewBlockSubscriptions sync.Mutex                             // protects newBlocksSubscriptions
+	newBlockSubscriptions   map[string]func(core.ChainEvent) error // callbacks for new block subscriptions
+	am                      *accounts.Manager
+	miner                   *miner.Miner
 }
 
 // NewPublicBlockChainAPI creates a new Etheruem blockchain API.
 func NewPublicBlockChainAPI(config *core.ChainConfig, bc *core.BlockChain, m *miner.Miner, chainDb ethdb.Database, eventMux *event.TypeMux, am *accounts.Manager) *PublicBlockChainAPI {
-	return &PublicBlockChainAPI{config: config, bc: bc, miner: m, chainDb: chainDb, eventMux: eventMux, am: am}
+	api := &PublicBlockChainAPI{
+		config:   config,
+		bc:       bc,
+		miner:    m,
+		chainDb:  chainDb,
+		eventMux: eventMux,
+		am:       am,
+		newBlockSubscriptions: make(map[string]func(core.ChainEvent) error),
+	}
+
+	go api.subscriptionLoop()
+
+	return api
+}
+
+// subscriptionLoop reads events from the global event mux and creates notifications for the matched subscriptions.
+func (s *PublicBlockChainAPI) subscriptionLoop() {
+	sub := s.eventMux.Subscribe(core.ChainEvent{})
+	for event := range sub.Chan() {
+		if chainEvent, ok := event.Data.(core.ChainEvent); ok {
+			s.muNewBlockSubscriptions.Lock()
+			for id, notifyOf := range s.newBlockSubscriptions {
+				if notifyOf(chainEvent) == rpc.ErrNotificationNotFound {
+					delete(s.newBlockSubscriptions, id)
+				}
+			}
+			s.muNewBlockSubscriptions.Unlock()
+		}
+	}
 }
 
 // BlockNumber returns the block number of the chain head.
@@ -564,20 +596,36 @@ type NewBlocksArgs struct {
 
 // NewBlocks triggers a new block event each time a block is appended to the chain. It accepts an argument which allows
 // the caller to specify whether the output should contain transactions and in what format.
-func (s *PublicBlockChainAPI) NewBlocks(args NewBlocksArgs) (rpc.Subscription, error) {
-	sub := s.eventMux.Subscribe(core.ChainEvent{})
+func (s *PublicBlockChainAPI) NewBlocks(ctx context.Context, args NewBlocksArgs) (rpc.Subscription, error) {
+	notifier, supported := ctx.Value(rpc.NotifierContextKey).(rpc.Notifier)
+	if !supported {
+		return nil, rpc.ErrNotificationsUnsupported
+	}
 
-	output := func(rawBlock interface{}) interface{} {
-		if event, ok := rawBlock.(core.ChainEvent); ok {
-			notification, err := s.rpcOutputBlock(event.Block, args.IncludeTransactions, args.TransactionDetails)
-			if err == nil {
-				return notification
-			}
+	// create a subscription that will remove itself when unsubscribed/cancelled
+	subscription, err := notifier.NewSubscription(func(subId string) {
+		s.muNewBlockSubscriptions.Lock()
+		delete(s.newBlockSubscriptions, subId)
+		s.muNewBlockSubscriptions.Unlock()
+	})
+
+	if err != nil {
+		return nil, err
+	}
+
+	// add a callback that is called on chain events which will format the block and notify the client
+	s.muNewBlockSubscriptions.Lock()
+	s.newBlockSubscriptions[subscription.ID()] = func(e core.ChainEvent) error {
+		if notification, err := s.rpcOutputBlock(e.Block, args.IncludeTransactions, args.TransactionDetails); err == nil {
+			return subscription.Notify(notification)
+		} else {
+			glog.V(logger.Warn).Info("unable to format block %v\n", err)
 		}
-		return rawBlock
+		return nil
 	}
+	s.muNewBlockSubscriptions.Unlock()
 
-	return rpc.NewSubscriptionWithOutputFormat(sub, output), nil
+	return subscription, nil
 }
 
 // GetCode returns the code stored at the given address in the state for the given block number.
@@ -821,26 +869,75 @@ func newRPCTransaction(b *types.Block, txHash common.Hash) (*RPCTransaction, err
 
 // PublicTransactionPoolAPI exposes methods for the RPC interface
 type PublicTransactionPoolAPI struct {
-	eventMux *event.TypeMux
-	chainDb  ethdb.Database
-	gpo      *GasPriceOracle
-	bc       *core.BlockChain
-	miner    *miner.Miner
-	am       *accounts.Manager
-	txPool   *core.TxPool
-	txMu     sync.Mutex
+	eventMux        *event.TypeMux
+	chainDb         ethdb.Database
+	gpo             *GasPriceOracle
+	bc              *core.BlockChain
+	miner           *miner.Miner
+	am              *accounts.Manager
+	txPool          *core.TxPool
+	txMu            sync.Mutex
+	muPendingTxSubs sync.Mutex
+	pendingTxSubs   map[string]rpc.Subscription
 }
 
 // NewPublicTransactionPoolAPI creates a new RPC service with methods specific for the transaction pool.
 func NewPublicTransactionPoolAPI(e *Ethereum) *PublicTransactionPoolAPI {
-	return &PublicTransactionPoolAPI{
-		eventMux: e.EventMux(),
-		gpo:      NewGasPriceOracle(e),
-		chainDb:  e.ChainDb(),
-		bc:       e.BlockChain(),
-		am:       e.AccountManager(),
-		txPool:   e.TxPool(),
-		miner:    e.Miner(),
+	api := &PublicTransactionPoolAPI{
+		eventMux:      e.EventMux(),
+		gpo:           NewGasPriceOracle(e),
+		chainDb:       e.ChainDb(),
+		bc:            e.BlockChain(),
+		am:            e.AccountManager(),
+		txPool:        e.TxPool(),
+		miner:         e.Miner(),
+		pendingTxSubs: make(map[string]rpc.Subscription),
+	}
+
+	go api.subscriptionLoop()
+
+	return api
+}
+
+// subscriptionLoop listens for events on the global event mux and creates notifications for subscriptions.
+func (s *PublicTransactionPoolAPI) subscriptionLoop() {
+	sub := s.eventMux.Subscribe(core.TxPreEvent{})
+	accountTimeout := time.NewTicker(10 * time.Second)
+
+	// only publish pending tx signed by one of the accounts in the node
+	accountSet := set.New()
+	accounts, _ := s.am.Accounts()
+	for _, acc := range accounts {
+		accountSet.Add(acc.Address)
+	}
+
+	for {
+		select {
+		case event := <-sub.Chan():
+			if event == nil {
+				continue
+			}
+			tx := event.Data.(core.TxPreEvent)
+			if from, err := tx.Tx.FromFrontier(); err == nil {
+				if accountSet.Has(from) {
+					s.muPendingTxSubs.Lock()
+					for id, sub := range s.pendingTxSubs {
+						if sub.Notify(tx.Tx.Hash()) == rpc.ErrNotificationNotFound {
+							delete(s.pendingTxSubs, id)
+						}
+					}
+					s.muPendingTxSubs.Unlock()
+				}
+			}
+		case <-accountTimeout.C:
+			// refresh account list when accounts are added/removed from the node.
+			if accounts, err := s.am.Accounts(); err == nil {
+				accountSet.Clear()
+				for _, acc := range accounts {
+					accountSet.Add(acc.Address)
+				}
+			}
+		}
 	}
 }
 
@@ -1275,40 +1372,27 @@ func (s *PublicTransactionPoolAPI) PendingTransactions() ([]*RPCTransaction, err
 
 // NewPendingTransaction creates a subscription that is triggered each time a transaction enters the transaction pool
 // and is send from one of the transactions this nodes manages.
-func (s *PublicTransactionPoolAPI) NewPendingTransactions() (rpc.Subscription, error) {
-	sub := s.eventMux.Subscribe(core.TxPreEvent{})
-
-	accounts, err := s.am.Accounts()
-	if err != nil {
-		return rpc.Subscription{}, err
+func (s *PublicTransactionPoolAPI) NewPendingTransactions(ctx context.Context) (rpc.Subscription, error) {
+	notifier, supported := ctx.Value(rpc.NotifierContextKey).(rpc.Notifier)
+	if !supported {
+		return nil, rpc.ErrNotificationsUnsupported
 	}
-	accountSet := set.New()
-	for _, account := range accounts {
-		accountSet.Add(account.Address)
-	}
-	accountSetLastUpdates := time.Now()
 
-	output := func(transaction interface{}) interface{} {
-		if time.Since(accountSetLastUpdates) > (time.Duration(2) * time.Second) {
-			if accounts, err = s.am.Accounts(); err != nil {
-				accountSet.Clear()
-				for _, account := range accounts {
-					accountSet.Add(account.Address)
-				}
-				accountSetLastUpdates = time.Now()
-			}
-		}
+	subscription, err := notifier.NewSubscription(func(id string) {
+		s.muPendingTxSubs.Lock()
+		delete(s.pendingTxSubs, id)
+		s.muPendingTxSubs.Unlock()
+	})
 
-		tx := transaction.(core.TxPreEvent)
-		if from, err := tx.Tx.FromFrontier(); err == nil {
-			if accountSet.Has(from) {
-				return tx.Tx.Hash()
-			}
-		}
-		return nil
+	if err != nil {
+		return nil, err
 	}
 
-	return rpc.NewSubscriptionWithOutputFormat(sub, output), nil
+	s.muPendingTxSubs.Lock()
+	s.pendingTxSubs[subscription.ID()] = subscription
+	s.muPendingTxSubs.Unlock()
+
+	return subscription, nil
 }
 
 // Resend accepts an existing transaction and a new gas price and limit. It will remove the given transaction from the

eth/backend.go

@@ -310,7 +310,7 @@ func (s *Ethereum) APIs() []rpc.API {
 		}, {
 			Namespace: "eth",
 			Version:   "1.0",
-			Service:   downloader.NewPublicDownloaderAPI(s.Downloader()),
+			Service:   downloader.NewPublicDownloaderAPI(s.Downloader(), s.EventMux()),
 			Public:    true,
 		}, {
 			Namespace: "miner",

eth/downloader/api.go

@@ -17,18 +17,55 @@
 package downloader
 
 import (
+	"sync"
+
+	"golang.org/x/net/context"
+
+	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
 // PublicDownloaderAPI provides an API which gives information about the current synchronisation status.
 // It offers only methods that operates on data that can be available to anyone without security risks.
 type PublicDownloaderAPI struct {
-	d *Downloader
+	d                   *Downloader
+	mux                 *event.TypeMux
+	muSyncSubscriptions sync.Mutex
+	syncSubscriptions   map[string]rpc.Subscription
 }
 
 // NewPublicDownloaderAPI create a new PublicDownloaderAPI.
-func NewPublicDownloaderAPI(d *Downloader) *PublicDownloaderAPI {
-	return &PublicDownloaderAPI{d}
+func NewPublicDownloaderAPI(d *Downloader, m *event.TypeMux) *PublicDownloaderAPI {
+	api := &PublicDownloaderAPI{d: d, mux: m, syncSubscriptions: make(map[string]rpc.Subscription)}
+
+	go api.run()
+
+	return api
+}
+
+func (api *PublicDownloaderAPI) run() {
+	sub := api.mux.Subscribe(StartEvent{}, DoneEvent{}, FailedEvent{})
+
+	for event := range sub.Chan() {
+		var notification interface{}
+
+		switch event.Data.(type) {
+		case StartEvent:
+			result := &SyncingResult{Syncing: true}
+			result.Status.Origin, result.Status.Current, result.Status.Height, result.Status.Pulled, result.Status.Known = api.d.Progress()
+			notification = result
+		case DoneEvent, FailedEvent:
+			notification = false
+		}
+
+		api.muSyncSubscriptions.Lock()
+		for id, sub := range api.syncSubscriptions {
+			if sub.Notify(notification) == rpc.ErrNotificationNotFound {
+				delete(api.syncSubscriptions, id)
+			}
+		}
+		api.muSyncSubscriptions.Unlock()
+	}
 }
 
 // Progress gives progress indications when the node is synchronising with the Ethereum network.
@@ -47,19 +84,25 @@ type SyncingResult struct {
 }
 
 // Syncing provides information when this nodes starts synchronising with the Ethereum network and when it's finished.
-func (s *PublicDownloaderAPI) Syncing() (rpc.Subscription, error) {
-	sub := s.d.mux.Subscribe(StartEvent{}, DoneEvent{}, FailedEvent{})
+func (api *PublicDownloaderAPI) Syncing(ctx context.Context) (rpc.Subscription, error) {
+	notifier, supported := ctx.Value(rpc.NotifierContextKey).(rpc.Notifier)
+	if !supported {
+		return nil, rpc.ErrNotificationsUnsupported
+	}
 
-	output := func(event interface{}) interface{} {
-		switch event.(type) {
-		case StartEvent:
-			result := &SyncingResult{Syncing: true}
-			result.Status.Origin, result.Status.Current, result.Status.Height, result.Status.Pulled, result.Status.Known = s.d.Progress()
-			return result
-		case DoneEvent, FailedEvent:
-			return false
-		}
-		return nil
+	subscription, err := notifier.NewSubscription(func(id string) {
+		api.muSyncSubscriptions.Lock()
+		delete(api.syncSubscriptions, id)
+		api.muSyncSubscriptions.Unlock()
+	})
+
+	if err != nil {
+		return nil, err
 	}
-	return rpc.NewSubscriptionWithOutputFormat(sub, output), nil
+
+	api.muSyncSubscriptions.Lock()
+	api.syncSubscriptions[subscription.ID()] = subscription
+	api.muSyncSubscriptions.Unlock()
+
+	return subscription, nil
 }

eth/filters/api.go

@@ -17,15 +17,13 @@
 package filters
 
 import (
-	"sync"
-	"time"
-
 	"crypto/rand"
 	"encoding/hex"
-	"errors"
-
 	"encoding/json"
+	"errors"
 	"fmt"
+	"sync"
+	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -33,6 +31,8 @@ import (
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/event"
 	"github.com/ethereum/go-ethereum/rpc"
+
+	"golang.org/x/net/context"
 )
 
 var (
@@ -202,7 +202,7 @@ func (s *PublicFilterAPI) NewPendingTransactionFilter() (string, error) {
 }
 
 // newLogFilter creates a new log filter.
-func (s *PublicFilterAPI) newLogFilter(earliest, latest int64, addresses []common.Address, topics [][]common.Hash) (int, error) {
+func (s *PublicFilterAPI) newLogFilter(earliest, latest int64, addresses []common.Address, topics [][]common.Hash, callback func(log *vm.Log, removed bool)) (int, error) {
 	s.logMu.Lock()
 	defer s.logMu.Unlock()
 
@@ -219,17 +219,70 @@ func (s *PublicFilterAPI) newLogFilter(earliest, latest int64, addresses []commo
 	filter.SetAddresses(addresses)
 	filter.SetTopics(topics)
 	filter.LogCallback = func(log *vm.Log, removed bool) {
-		s.logMu.Lock()
-		defer s.logMu.Unlock()
-
-		if queue := s.logQueue[id]; queue != nil {
-			queue.add(vmlog{log, removed})
+		if callback != nil {
+			callback(log, removed)
+		} else {
+			s.logMu.Lock()
+			defer s.logMu.Unlock()
+			if queue := s.logQueue[id]; queue != nil {
+				queue.add(vmlog{log, removed})
+			}
 		}
 	}
 
 	return id, nil
 }
 
+func (s *PublicFilterAPI) Logs(ctx context.Context, args NewFilterArgs) (rpc.Subscription, error) {
+	notifier, supported := ctx.Value(rpc.NotifierContextKey).(rpc.Notifier)
+	if !supported {
+		return nil, rpc.ErrNotificationsUnsupported
+	}
+
+	var (
+		externalId   string
+		subscription rpc.Subscription
+		err          error
+	)
+
+	if externalId, err = newFilterId(); err != nil {
+		return nil, err
+	}
+
+	// uninstall filter when subscription is unsubscribed/cancelled
+	if subscription, err = notifier.NewSubscription(func(string) {
+		s.UninstallFilter(externalId)
+	}); err != nil {
+		return nil, err
+	}
+
+	notifySubscriber := func(log *vm.Log, removed bool) {
+		rpcLog := toRPCLogs(vm.Logs{log}, removed)
+		if err := subscription.Notify(rpcLog); err != nil {
+			subscription.Cancel()
+		}
+	}
+
+	// from and to block number are not used since subscriptions don't allow you to travel to "time"
+	var id int
+	if len(args.Addresses) > 0 {
+		id, err = s.newLogFilter(-1, -1, args.Addresses, args.Topics, notifySubscriber)
+	} else {
+		id, err = s.newLogFilter(-1, -1, nil, args.Topics, notifySubscriber)
+	}
+
+	if err != nil {
+		subscription.Cancel()
+		return nil, err
+	}
+
+	s.filterMapMu.Lock()
+	s.filterMapping[externalId] = id
+	s.filterMapMu.Unlock()
+
+	return subscription, err
+}
+
 // NewFilterArgs represents a request to create a new filter.
 type NewFilterArgs struct {
 	FromBlock rpc.BlockNumber
@@ -364,9 +417,9 @@ func (s *PublicFilterAPI) NewFilter(args NewFilterArgs) (string, error) {
 
 	var id int
 	if len(args.Addresses) > 0 {
-		id, err = s.newLogFilter(args.FromBlock.Int64(), args.ToBlock.Int64(), args.Addresses, args.Topics)
+		id, err = s.newLogFilter(args.FromBlock.Int64(), args.ToBlock.Int64(), args.Addresses, args.Topics, nil)
 	} else {
-		id, err = s.newLogFilter(args.FromBlock.Int64(), args.ToBlock.Int64(), nil, args.Topics)
+		id, err = s.newLogFilter(args.FromBlock.Int64(), args.ToBlock.Int64(), nil, args.Topics, nil)
 	}
 	if err != nil {
 		return "", err

node/node.go

@@ -303,7 +303,7 @@ func (n *Node) startIPC(apis []rpc.API) error {
 				glog.V(logger.Error).Infof("IPC accept failed: %v", err)
 				continue
 			}
-			go handler.ServeCodec(rpc.NewJSONCodec(conn))
+			go handler.ServeCodec(rpc.NewJSONCodec(conn), rpc.OptionMethodInvocation | rpc.OptionSubscriptions)
 		}
 	}()
 	// All listeners booted successfully

rpc/doc.go

@@ -68,35 +68,19 @@ The package also supports the publish subscribe pattern through the use of subsc
 A method that is considered eligible for notifications must satisfy the following criteria:
  - object must be exported
  - method must be exported
+ - first method argument type must be context.Context
  - method argument(s) must be exported or builtin types
  - method must return the tuple Subscription, error
 
-
 An example method:
- func (s *BlockChainService) Head() (Subscription, error) {
- 	sub := s.bc.eventMux.Subscribe(ChainHeadEvent{})
-	return v2.NewSubscription(sub), nil
- }
-
-This method will push all raised ChainHeadEvents to subscribed clients. If the client is only
-interested in every N'th block it is possible to add a criteria.
-
- func (s *BlockChainService) HeadFiltered(nth uint64) (Subscription, error) {
- 	sub := s.bc.eventMux.Subscribe(ChainHeadEvent{})
-
-	criteria := func(event interface{}) bool {
-		chainHeadEvent := event.(ChainHeadEvent)
-		if chainHeadEvent.Block.NumberU64() % nth == 0 {
-			return true
-		}
-		return false
-	}
-
-	return v2.NewSubscriptionFiltered(sub, criteria), nil
+ func (s *BlockChainService) NewBlocks(ctx context.Context) (Subscription, error) {
+ 	...
  }
 
 Subscriptions are deleted when:
  - the user sends an unsubscribe request
- - the connection which was used to create the subscription is closed
+ - the connection which was used to create the subscription is closed. This can be initiated
+   by the client and server. The server will close the connection on an write error or when
+   the queue of buffered notifications gets too big.
 */
 package rpc

rpc/http.go

@@ -126,7 +126,7 @@ func newJSONHTTPHandler(srv *Server) http.HandlerFunc {
 		// a single request.
 		codec := NewJSONCodec(&httpReadWriteNopCloser{r.Body, w})
 		defer codec.Close()
-		srv.ServeSingleRequest(codec)
+		srv.ServeSingleRequest(codec, OptionMethodInvocation)
 	}
 }
 

rpc/inproc.go

@@ -39,7 +39,7 @@ func (c *inProcClient) Close() {
 // RPC server.
 func NewInProcRPCClient(handler *Server) Client {
 	p1, p2 := net.Pipe()
-	go handler.ServeCodec(NewJSONCodec(p1))
+	go handler.ServeCodec(NewJSONCodec(p1), OptionMethodInvocation|OptionSubscriptions)
 	return &inProcClient{handler, p2, json.NewEncoder(p2), json.NewDecoder(p2)}
 }
 

rpc/json.go

@@ -22,7 +22,7 @@ import (
 	"io"
 	"reflect"
 	"strings"
-	"sync/atomic"
+	"sync"
 
 	"github.com/ethereum/go-ethereum/logger"
 	"github.com/ethereum/go-ethereum/logger/glog"
@@ -81,19 +81,20 @@ type jsonNotification struct {
 // jsonCodec reads and writes JSON-RPC messages to the underlying connection. It also has support for parsing arguments
 // and serializing (result) objects.
 type jsonCodec struct {
-	closed   chan interface{}
-	isClosed int32
-	d        *json.Decoder
-	e        *json.Encoder
-	req      JSONRequest
-	rw       io.ReadWriteCloser
+	closed    chan interface{}
+	closer    sync.Once
+	d         *json.Decoder
+	muEncoder sync.Mutex
+	e         *json.Encoder
+	req       JSONRequest
+	rw        io.ReadWriteCloser
 }
 
 // NewJSONCodec creates a new RPC server codec with support for JSON-RPC 2.0
 func NewJSONCodec(rwc io.ReadWriteCloser) ServerCodec {
 	d := json.NewDecoder(rwc)
 	d.UseNumber()
-	return &jsonCodec{closed: make(chan interface{}), d: d, e: json.NewEncoder(rwc), rw: rwc, isClosed: 0}
+	return &jsonCodec{closed: make(chan interface{}), d: d, e: json.NewEncoder(rwc), rw: rwc}
 }
 
 // isBatch returns true when the first non-whitespace characters is '['
@@ -326,15 +327,18 @@ func (c *jsonCodec) CreateNotification(subid string, event interface{}) interfac
 
 // Write message to client
 func (c *jsonCodec) Write(res interface{}) error {
+	c.muEncoder.Lock()
+	defer c.muEncoder.Unlock()
+
 	return c.e.Encode(res)
 }
 
 // Close the underlying connection
 func (c *jsonCodec) Close() {
-	if atomic.CompareAndSwapInt32(&c.isClosed, 0, 1) {
+	c.closer.Do(func() {
 		close(c.closed)
 		c.rw.Close()
-	}
+	})
 }
 
 // Closed returns a channel which will be closed when Close is called

rpc/notification_test.go

+// Copyright 2016 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 rpc
+
+import (
+	"encoding/json"
+	"net"
+	"testing"
+	"time"
+
+	"golang.org/x/net/context"
+)
+
+type NotificationTestService struct{}
+
+var (
+	unsubCallbackCalled = false
+)
+
+func (s *NotificationTestService) Unsubscribe(subid string) {
+	unsubCallbackCalled = true
+}
+
+func (s *NotificationTestService) SomeSubscription(ctx context.Context, n, val int) (Subscription, error) {
+	notifier, supported := ctx.Value(NotifierContextKey).(Notifier)
+	if !supported {
+		return nil, ErrNotificationsUnsupported
+	}
+
+	// by explicitly creating an subscription we make sure that the subscription id is send back to the client
+	// before the first subscription.Notify is called. Otherwise the events might be send before the response
+	// for the eth_subscribe method.
+	subscription, err := notifier.NewSubscription(s.Unsubscribe)
+	if err != nil {
+		return nil, err
+	}
+
+	go func() {
+		for i := 0; i < n; i++ {
+			if err := subscription.Notify(val + i); err != nil {
+				return
+			}
+		}
+	}()
+
+	return subscription, nil
+}
+
+func TestNotifications(t *testing.T) {
+	server := NewServer()
+	service := &NotificationTestService{}
+
+	if err := server.RegisterName("eth", service); err != nil {
+		t.Fatalf("unable to register test service %v", err)
+	}
+
+	clientConn, serverConn := net.Pipe()
+
+	go server.ServeCodec(NewJSONCodec(serverConn), OptionMethodInvocation|OptionSubscriptions)
+
+	out := json.NewEncoder(clientConn)
+	in := json.NewDecoder(clientConn)
+
+	n := 5
+	val := 12345
+	request := map[string]interface{}{
+		"id":      1,
+		"method":  "eth_subscribe",
+		"version": "2.0",
+		"params":  []interface{}{"someSubscription", n, val},
+	}
+
+	// create subscription
+	if err := out.Encode(request); err != nil {
+		t.Fatal(err)
+	}
+
+	var subid string
+	response := JSONSuccessResponse{Result: subid}
+	if err := in.Decode(&response); err != nil {
+		t.Fatal(err)
+	}
+
+	var ok bool
+	if subid, ok = response.Result.(string); !ok {
+		t.Fatalf("expected subscription id, got %T", response.Result)
+	}
+
+	for i := 0; i < n; i++ {
+		var notification jsonNotification
+		if err := in.Decode(&notification); err != nil {
+			t.Fatalf("%v", err)
+		}
+
+		if int(notification.Params.Result.(float64)) != val+i {
+			t.Fatalf("expected %d, got %d", val+i, notification.Params.Result)
+		}
+	}
+
+	clientConn.Close() // causes notification unsubscribe callback to be called
+	time.Sleep(1 * time.Second)
+
+	if !unsubCallbackCalled {
+		t.Error("unsubscribe callback not called after closing connection")
+	}
+}

rpc/server_test.go

@@ -65,8 +65,12 @@ func (s *Service) InvalidRets3() (string, string, error) {
 	return "", "", nil
 }
 
-func (s *Service) Subscription() (Subscription, error) {
-	return NewSubscription(nil), nil
+func (s *Service) Subscription(ctx context.Context) (Subscription, error) {
+	return nil, nil
+}
+
+func (s *Service) SubsriptionWithArgs(ctx context.Context, a, b int) (Subscription, error) {
+	return nil, nil
 }
 
 func TestServerRegisterName(t *testing.T) {
@@ -90,8 +94,8 @@ func TestServerRegisterName(t *testing.T) {
 		t.Errorf("Expected 4 callbacks for service 'calc', got %d", len(svc.callbacks))
 	}
 
-	if len(svc.subscriptions) != 1 {
-		t.Errorf("Expected 1 subscription for service 'calc', got %d", len(svc.subscriptions))
+	if len(svc.subscriptions) != 2 {
+		t.Errorf("Expected 2 subscriptions for service 'calc', got %d", len(svc.subscriptions))
 	}
 }
 
@@ -229,7 +233,7 @@ func TestServerMethodExecution(t *testing.T) {
 
 	input, _ := json.Marshal(&req)
 	codec := &ServerTestCodec{input: input, closer: make(chan interface{})}
-	go server.ServeCodec(codec)
+	go server.ServeCodec(codec, OptionMethodInvocation)
 
 	<-codec.closer
 
@@ -259,7 +263,7 @@ func TestServerMethodWithCtx(t *testing.T) {
 
 	input, _ := json.Marshal(&req)
 	codec := &ServerTestCodec{input: input, closer: make(chan interface{})}
-	go server.ServeCodec(codec)
+	go server.ServeCodec(codec, OptionMethodInvocation)
 
 	<-codec.closer
 

rpc/types.go

@@ -24,7 +24,6 @@ import (
 	"strings"
 	"sync"
 
-	"github.com/ethereum/go-ethereum/event"
 	"gopkg.in/fatih/set.v0"
 )
 
@@ -66,10 +65,10 @@ type serverRequest struct {
 	err           RPCError
 }
 
-type serviceRegistry map[string]*service          // collection of services
-type callbacks map[string]*callback               // collection of RPC callbacks
-type subscriptions map[string]*callback           // collection of subscription callbacks
-type subscriptionRegistry map[string]Subscription // collection of subscriptions
+type serviceRegistry map[string]*service       // collection of services
+type callbacks map[string]*callback            // collection of RPC callbacks
+type subscriptions map[string]*callback        // collection of subscription callbacks
+type subscriptionRegistry map[string]*callback // collection of subscription callbacks
 
 // Server represents a RPC server
 type Server struct {
@@ -123,51 +122,6 @@ type ServerCodec interface {
 	Closed() <-chan interface{}
 }
 
-// SubscriptionMatcher returns true if the given value matches the criteria specified by the user
-type SubscriptionMatcher func(interface{}) bool
-
-// SubscriptionOutputFormat accepts event data and has the ability to format the data before it is send to the client
-type SubscriptionOutputFormat func(interface{}) interface{}
-
-// defaultSubscriptionOutputFormatter returns data and is used as default output format for notifications
-func defaultSubscriptionOutputFormatter(data interface{}) interface{} {
-	return data
-}
-
-// Subscription is used by the server to send notifications to the client
-type Subscription struct {
-	sub    event.Subscription
-	match  SubscriptionMatcher
-	format SubscriptionOutputFormat
-}
-
-// NewSubscription create a new RPC subscription
-func NewSubscription(sub event.Subscription) Subscription {
-	return Subscription{sub, nil, defaultSubscriptionOutputFormatter}
-}
-
-// NewSubscriptionWithOutputFormat create a new RPC subscription which a custom notification output format
-func NewSubscriptionWithOutputFormat(sub event.Subscription, formatter SubscriptionOutputFormat) Subscription {
-	return Subscription{sub, nil, formatter}
-}
-
-// NewSubscriptionFiltered will create a new subscription. For each raised event the given matcher is
-// called. If it returns true the event is send as notification to the client, otherwise it is ignored.
-func NewSubscriptionFiltered(sub event.Subscription, match SubscriptionMatcher) Subscription {
-	return Subscription{sub, match, defaultSubscriptionOutputFormatter}
-}
-
-// Chan returns the channel where new events will be published. It's up the user to call the matcher to
-// determine if the events are interesting for the client.
-func (s *Subscription) Chan() <-chan *event.Event {
-	return s.sub.Chan()
-}
-
-// Unsubscribe will end the subscription and closes the event channel
-func (s *Subscription) Unsubscribe() {
-	s.sub.Unsubscribe()
-}
-
 // HexNumber serializes a number to hex format using the "%#x" format
 type HexNumber big.Int
 

rpc/utils.go

@@ -45,6 +45,16 @@ func isExportedOrBuiltinType(t reflect.Type) bool {
 	return isExported(t.Name()) || t.PkgPath() == ""
 }
 
+var contextType = reflect.TypeOf((*context.Context)(nil)).Elem()
+
+// isContextType returns an indication if the given t is of context.Context or *context.Context type
+func isContextType(t reflect.Type) bool {
+	for t.Kind() == reflect.Ptr {
+		t = t.Elem()
+	}
+	return t == contextType
+}
+
 var errorType = reflect.TypeOf((*error)(nil)).Elem()
 
 // Implements this type the error interface
@@ -57,6 +67,7 @@ func isErrorType(t reflect.Type) bool {
 
 var subscriptionType = reflect.TypeOf((*Subscription)(nil)).Elem()
 
+// isSubscriptionType returns an indication if the given t is of Subscription or *Subscription type
 func isSubscriptionType(t reflect.Type) bool {
 	for t.Kind() == reflect.Ptr {
 		t = t.Elem()
@@ -64,12 +75,17 @@ func isSubscriptionType(t reflect.Type) bool {
 	return t == subscriptionType
 }
 
-// isPubSub tests whether the given method return the pair (v2.Subscription, error)
+// isPubSub tests whether the given method has as as first argument a context.Context
+// and returns the pair (Subscription, error)
 func isPubSub(methodType reflect.Type) bool {
-	if methodType.NumOut() != 2 {
+	// numIn(0) is the receiver type
+	if methodType.NumIn() < 2 || methodType.NumOut() != 2 {
 		return false
 	}
-	return isSubscriptionType(methodType.Out(0)) && isErrorType(methodType.Out(1))
+
+	return isContextType(methodType.In(1)) &&
+		isSubscriptionType(methodType.Out(0)) &&
+		isErrorType(methodType.Out(1))
 }
 
 // formatName will convert to first character to lower case
@@ -110,8 +126,6 @@ func isBlockNumber(t reflect.Type) bool {
 	return t == blockNumberType
 }
 
-var contextType = reflect.TypeOf(new(context.Context)).Elem()
-
 // suitableCallbacks iterates over the methods of the given type. It will determine if a method satisfies the criteria
 // for a RPC callback or a subscription callback and adds it to the collection of callbacks or subscriptions. See server
 // documentation for a summary of these criteria.
@@ -205,7 +219,7 @@ METHODS:
 	return callbacks, subscriptions
 }
 
-func newSubscriptionId() (string, error) {
+func newSubscriptionID() (string, error) {
 	var subid [16]byte
 	n, _ := rand.Read(subid[:])
 	if n != 16 {

rpc/websocket.go

@@ -93,7 +93,8 @@ func NewWSServer(cors string, handler *Server) *http.Server {
 		Handler: websocket.Server{
 			Handshake: wsHandshakeValidator(strings.Split(cors, ",")),
 			Handler: func(conn *websocket.Conn) {
-				handler.ServeCodec(NewJSONCodec(&wsReaderWriterCloser{conn}))
+				handler.ServeCodec(NewJSONCodec(&wsReaderWriterCloser{conn}),
+					OptionMethodInvocation|OptionSubscriptions)
 			},
 		},
 	}