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rpc: add pub/sub support

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This commit is contained in:
Bas van Kervel
2016-03-29 15:07:40 +02:00
parent fb578f4550
commit f7328c5ecb
16 changed files with 849 additions and 315 deletions
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230
rpc/server.go
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@ -23,7 +23,6 @@ import (
"sync/atomic"
"time"
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"golang.org/x/net/context"
@ -33,10 +32,26 @@ import (
const (
stopPendingRequestTimeout = 3 * time.Second // give pending requests stopPendingRequestTimeout the time to finish when the server is stopped
// NotifierContextKey is the key where the notifier associated with the codec is stored in the context
NotifierContextKey = 1
notificationBufferSize = 10000 // max buffered notifications before codec is closed
DefaultIPCApis = "admin,eth,debug,miner,net,shh,txpool,personal,web3"
DefaultHTTPApis = "eth,net,web3"
)
// CodecOption specifies which type of messages this codec supports
type CodecOption int
const (
// OptionMethodInvocation is an indication that the codec supports RPC method calls
OptionMethodInvocation CodecOption = 1 << iota
// OptionSubscriptions is an indication that the codec suports RPC notifications
OptionSubscriptions = 1 << iota // support pub sub
)
// NewServer will create a new server instance with no registered handlers.
func NewServer() *Server {
server := &Server{
@ -63,7 +78,7 @@ type RPCService struct {
// Modules returns the list of RPC services with their version number
func (s *RPCService) Modules() map[string]string {
modules := make(map[string]string)
for name, _ := range s.server.services {
for name := range s.server.services {
modules[name] = "1.0"
}
return modules
@ -92,7 +107,7 @@ func (s *Server) RegisterName(name string, rcvr interface{}) error {
if regsvc, present := s.services[name]; present {
methods, subscriptions := suitableCallbacks(rcvrVal, svc.typ)
if len(methods) == 0 && len(subscriptions) == 0 {
return fmt.Errorf("Service doesn't have any suitable methods/subscriptions to expose")
return fmt.Errorf("Service %T doesn't have any suitable methods/subscriptions to expose", rcvr)
}
for _, m := range methods {
@ -109,7 +124,7 @@ func (s *Server) RegisterName(name string, rcvr interface{}) error {
svc.callbacks, svc.subscriptions = suitableCallbacks(rcvrVal, svc.typ)
if len(svc.callbacks) == 0 && len(svc.subscriptions) == 0 {
return fmt.Errorf("Service doesn't have any suitable methods/subscriptions to expose")
return fmt.Errorf("Service %T doesn't have any suitable methods/subscriptions to expose", rcvr)
}
s.services[svc.name] = svc
@ -117,12 +132,23 @@ func (s *Server) RegisterName(name string, rcvr interface{}) error {
return nil
}
// hasOption returns true if option is included in options, otherwise false
func hasOption(option CodecOption, options []CodecOption) bool {
for _, o := range options {
if option == o {
return true
}
}
return false
}
// serveRequest will reads requests from the codec, calls the RPC callback and
// writes the response to the given codec.
//
// If singleShot is true it will process a single request, otherwise it will handle
// requests until the codec returns an error when reading a request (in most cases
// an EOF). It executes requests in parallel when singleShot is false.
func (s *Server) serveRequest(codec ServerCodec, singleShot bool) error {
func (s *Server) serveRequest(codec ServerCodec, singleShot bool, options CodecOption) error {
defer func() {
if err := recover(); err != nil {
const size = 64 << 10
@ -141,6 +167,12 @@ func (s *Server) serveRequest(codec ServerCodec, singleShot bool) error {
ctx, cancel := context.WithCancel(context.Background())
defer cancel()
// if the codec supports notification include a notifier that callbacks can use
// to send notification to clients. It is thight to the codec/connection. If the
// connection is closed the notifier will stop and cancels all active subscriptions.
if options&OptionSubscriptions == OptionSubscriptions {
ctx = context.WithValue(ctx, NotifierContextKey, newBufferedNotifier(codec, notificationBufferSize))
}
s.codecsMu.Lock()
if atomic.LoadInt32(&s.run) != 1 { // server stopped
s.codecsMu.Unlock()
@ -193,20 +225,16 @@ func (s *Server) serveRequest(codec ServerCodec, singleShot bool) error {
// ServeCodec reads incoming requests from codec, calls the appropriate callback and writes the
// response back using the given codec. It will block until the codec is closed or the server is
// stopped. In either case the codec is closed.
//
// This server will:
// 1. allow for asynchronous and parallel request execution
// 2. supports notifications (pub/sub)
// 3. supports request batches
func (s *Server) ServeCodec(codec ServerCodec) {
func (s *Server) ServeCodec(codec ServerCodec, options CodecOption) {
defer codec.Close()
s.serveRequest(codec, false)
s.serveRequest(codec, false, options)
}
// ServeSingleRequest reads and processes a single RPC request from the given codec. It will not
// close the codec unless a non-recoverable error has occurred.
func (s *Server) ServeSingleRequest(codec ServerCodec) {
s.serveRequest(codec, true)
// close the codec unless a non-recoverable error has occurred. Note, this method will return after
// a single request has been processed!
func (s *Server) ServeSingleRequest(codec ServerCodec, options CodecOption) {
s.serveRequest(codec, true, options)
}
// Stop will stop reading new requests, wait for stopPendingRequestTimeout to allow pending requests to finish,
@ -225,122 +253,64 @@ func (s *Server) Stop() {
}
}
// sendNotification will create a notification from the given event by serializing member fields of the event.
// It will then send the notification to the client, when it fails the codec is closed. When the event has multiple
// fields an array of values is returned.
func sendNotification(codec ServerCodec, subid string, event interface{}) {
notification := codec.CreateNotification(subid, event)
if err := codec.Write(notification); err != nil {
codec.Close()
}
}
// createSubscription will register a new subscription and waits for raised events. When an event is raised it will:
// 1. test if the event is raised matches the criteria the user has (optionally) specified
// 2. create a notification of the event and send it the client when it matches the criteria
// It will unsubscribe the subscription when the socket is closed or the subscription is unsubscribed by the user.
func (s *Server) createSubscription(c ServerCodec, req *serverRequest) (string, error) {
args := []reflect.Value{req.callb.rcvr}
if len(req.args) > 0 {
args = append(args, req.args...)
}
subid, err := newSubscriptionId()
if err != nil {
return "", err
}
// createSubscription will call the subscription callback and returns the subscription id or error.
func (s *Server) createSubscription(ctx context.Context, c ServerCodec, req *serverRequest) (string, error) {
// subscription have as first argument the context following optional arguments
args := []reflect.Value{req.callb.rcvr, reflect.ValueOf(ctx)}
args = append(args, req.args...)
reply := req.callb.method.Func.Call(args)
if reply[1].IsNil() { // no error
if subscription, ok := reply[0].Interface().(Subscription); ok {
s.muSubcriptions.Lock()
s.subscriptions[subid] = subscription
s.muSubcriptions.Unlock()
go func() {
cases := []reflect.SelectCase{
reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(subscription.Chan())}, // new event
reflect.SelectCase{Dir: reflect.SelectRecv, Chan: reflect.ValueOf(c.Closed())}, // connection closed
}
for {
idx, notification, recvOk := reflect.Select(cases)
switch idx {
case 0: // new event, or channel closed
if recvOk { // send notification
if event, ok := notification.Interface().(*event.Event); ok {
if subscription.match == nil || subscription.match(event.Data) {
sendNotification(c, subid, subscription.format(event.Data))
}
}
} else { // user send an eth_unsubscribe request
return
}
case 1: // connection closed
s.unsubscribe(subid)
return
}
}
}()
} else { // unable to create subscription
s.muSubcriptions.Lock()
delete(s.subscriptions, subid)
s.muSubcriptions.Unlock()
}
} else {
return "", fmt.Errorf("Unable to create subscription")
if !reply[1].IsNil() { // subscription creation failed
return "", reply[1].Interface().(error)
}
return subid, nil
}
// unsubscribe calls the Unsubscribe method on the subscription and removes a subscription from the subscription
// registry.
func (s *Server) unsubscribe(subid string) bool {
s.muSubcriptions.Lock()
defer s.muSubcriptions.Unlock()
if sub, ok := s.subscriptions[subid]; ok {
sub.Unsubscribe()
delete(s.subscriptions, subid)
return true
}
return false
return reply[0].Interface().(Subscription).ID(), nil
}
// handle executes a request and returns the response from the callback.
func (s *Server) handle(ctx context.Context, codec ServerCodec, req *serverRequest) interface{} {
func (s *Server) handle(ctx context.Context, codec ServerCodec, req *serverRequest) (interface{}, func()) {
if req.err != nil {
return codec.CreateErrorResponse(&req.id, req.err)
return codec.CreateErrorResponse(&req.id, req.err), nil
}
if req.isUnsubscribe { // first param must be the subscription id
if req.isUnsubscribe { // cancel subscription, first param must be the subscription id
if len(req.args) >= 1 && req.args[0].Kind() == reflect.String {
subid := req.args[0].String()
if s.unsubscribe(subid) {
return codec.CreateResponse(req.id, true)
} else {
return codec.CreateErrorResponse(&req.id,
&callbackError{fmt.Sprintf("subscription '%s' not found", subid)})
notifier, supported := ctx.Value(NotifierContextKey).(*bufferedNotifier)
if !supported { // interface doesn't support subscriptions (e.g. http)
return codec.CreateErrorResponse(&req.id, &callbackError{ErrNotificationsUnsupported.Error()}), nil
}
subid := req.args[0].String()
if err := notifier.Unsubscribe(subid); err != nil {
return codec.CreateErrorResponse(&req.id, &callbackError{err.Error()}), nil
}
return codec.CreateResponse(req.id, true), nil
}
return codec.CreateErrorResponse(&req.id, &invalidParamsError{"Expected subscription id as argument"})
return codec.CreateErrorResponse(&req.id, &invalidParamsError{"Expected subscription id as first argument"}), nil
}
if req.callb.isSubscribe {
subid, err := s.createSubscription(codec, req)
subid, err := s.createSubscription(ctx, codec, req)
if err != nil {
return codec.CreateErrorResponse(&req.id, &callbackError{err.Error()})
return codec.CreateErrorResponse(&req.id, &callbackError{err.Error()}), nil
}
return codec.CreateResponse(req.id, subid)
// active the subscription after the sub id was successful sent to the client
activateSub := func() {
notifier, _ := ctx.Value(NotifierContextKey).(*bufferedNotifier)
notifier.activate(subid)
}
return codec.CreateResponse(req.id, subid), activateSub
}
// regular RPC call
// regular RPC call, prepare arguments
if len(req.args) != len(req.callb.argTypes) {
rpcErr := &invalidParamsError{fmt.Sprintf("%s%s%s expects %d parameters, got %d",
req.svcname, serviceMethodSeparator, req.callb.method.Name,
len(req.callb.argTypes), len(req.args))}
return codec.CreateErrorResponse(&req.id, rpcErr)
return codec.CreateErrorResponse(&req.id, rpcErr), nil
}
arguments := []reflect.Value{req.callb.rcvr}
@ -351,45 +321,56 @@ func (s *Server) handle(ctx context.Context, codec ServerCodec, req *serverReque
arguments = append(arguments, req.args...)
}
// execute RPC method and return result
reply := req.callb.method.Func.Call(arguments)
if len(reply) == 0 {
return codec.CreateResponse(req.id, nil)
return codec.CreateResponse(req.id, nil), nil
}
if req.callb.errPos >= 0 { // test if method returned an error
if !reply[req.callb.errPos].IsNil() {
e := reply[req.callb.errPos].Interface().(error)
res := codec.CreateErrorResponse(&req.id, &callbackError{e.Error()})
return res
return res, nil
}
}
return codec.CreateResponse(req.id, reply[0].Interface())
return codec.CreateResponse(req.id, reply[0].Interface()), nil
}
// exec executes the given request and writes the result back using the codec.
func (s *Server) exec(ctx context.Context, codec ServerCodec, req *serverRequest) {
var response interface{}
var callback func()
if req.err != nil {
response = codec.CreateErrorResponse(&req.id, req.err)
} else {
response = s.handle(ctx, codec, req)
response, callback = s.handle(ctx, codec, req)
}
if err := codec.Write(response); err != nil {
glog.V(logger.Error).Infof("%v\n", err)
codec.Close()
}
// when request was a subscribe request this allows these subscriptions to be actived
if callback != nil {
callback()
}
}
// execBatch executes the given requests and writes the result back using the codec. It will only write the response
// back when the last request is processed.
// execBatch executes the given requests and writes the result back using the codec.
// It will only write the response back when the last request is processed.
func (s *Server) execBatch(ctx context.Context, codec ServerCodec, requests []*serverRequest) {
responses := make([]interface{}, len(requests))
var callbacks []func()
for i, req := range requests {
if req.err != nil {
responses[i] = codec.CreateErrorResponse(&req.id, req.err)
} else {
responses[i] = s.handle(ctx, codec, req)
var callback func()
if responses[i], callback = s.handle(ctx, codec, req); callback != nil {
callbacks = append(callbacks, callback)
}
}
}
@ -397,11 +378,16 @@ func (s *Server) execBatch(ctx context.Context, codec ServerCodec, requests []*s
glog.V(logger.Error).Infof("%v\n", err)
codec.Close()
}
// when request holds one of more subscribe requests this allows these subscriptions to be actived
for _, c := range callbacks {
c()
}
}
// readRequest requests the next (batch) request from the codec. It will return the collection of requests, an
// indication if the request was a batch, the invalid request identifier and an error when the request could not be
// read/parsed.
// readRequest requests the next (batch) request from the codec. It will return the collection
// of requests, an indication if the request was a batch, the invalid request identifier and an
// error when the request could not be read/parsed.
func (s *Server) readRequest(codec ServerCodec) ([]*serverRequest, bool, RPCError) {
reqs, batch, err := codec.ReadRequestHeaders()
if err != nil {
@ -417,7 +403,7 @@ func (s *Server) readRequest(codec ServerCodec) ([]*serverRequest, bool, RPCErro
if r.isPubSub && r.method == unsubscribeMethod {
requests[i] = &serverRequest{id: r.id, isUnsubscribe: true}
argTypes := []reflect.Type{reflect.TypeOf("")}
argTypes := []reflect.Type{reflect.TypeOf("")} // expect subscription id as first arg
if args, err := codec.ParseRequestArguments(argTypes, r.params); err == nil {
requests[i].args = args
} else {
@ -426,12 +412,12 @@ func (s *Server) readRequest(codec ServerCodec) ([]*serverRequest, bool, RPCErro
continue
}
if svc, ok = s.services[r.service]; !ok {
if svc, ok = s.services[r.service]; !ok { // rpc method isn't available
requests[i] = &serverRequest{id: r.id, err: &methodNotFoundError{r.service, r.method}}
continue
}
if r.isPubSub { // eth_subscribe
if r.isPubSub { // eth_subscribe, r.method contains the subscription method name
if callb, ok := svc.subscriptions[r.method]; ok {
requests[i] = &serverRequest{id: r.id, svcname: svc.name, callb: callb}
if r.params != nil && len(callb.argTypes) > 0 {
@ -449,7 +435,7 @@ func (s *Server) readRequest(codec ServerCodec) ([]*serverRequest, bool, RPCErro
continue
}
if callb, ok := svc.callbacks[r.method]; ok {
if callb, ok := svc.callbacks[r.method]; ok { // lookup RPC method
requests[i] = &serverRequest{id: r.id, svcname: svc.name, callb: callb}
if r.params != nil && len(callb.argTypes) > 0 {
if args, err := codec.ParseRequestArguments(callb.argTypes, r.params); err == nil {