rpc: add pub/sub support

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