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rpc: remove NotifierContextKey

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Context keys must have a unique type in order to prevent
any unintented clashes. The code used int(1) as key.

Fix it by implementing the pattern recommended by package context.
This commit is contained in:
Felix Lange
2016-04-15 18:05:24 +02:00
parent 6197fbf8d7
commit a40e61b4ac
6 changed files with 18 additions and 12 deletions
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9
rpc/notification.go
View File

@ -23,6 +23,7 @@ import (
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"golang.org/x/net/context"
)
var (
@ -62,6 +63,14 @@ type Notifier interface {
Unsubscribe(id string) error
}
type notifierKey struct{}
// NotifierFromContext returns the Notifier value stored in ctx, if any.
func NotifierFromContext(ctx context.Context) (Notifier, bool) {
n, ok := ctx.Value(notifierKey{}).(Notifier)
return n, ok
}
// Subscription defines the interface for objects that can notify subscribers
type Subscription interface {
// Inform client of an event

2
rpc/notification_test.go
View File

@ -36,7 +36,7 @@ func (s *NotificationTestService) Unsubscribe(subid string) {
}
func (s *NotificationTestService) SomeSubscription(ctx context.Context, n, val int) (Subscription, error) {
notifier, supported := ctx.Value(NotifierContextKey).(Notifier)
notifier, supported := NotifierFromContext(ctx)
if !supported {
return nil, ErrNotificationsUnsupported
}

11
rpc/server.go
View File

@ -32,9 +32,6 @@ 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"
@ -171,7 +168,7 @@ func (s *Server) serveRequest(codec ServerCodec, singleShot bool, options CodecO
// 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))
ctx = context.WithValue(ctx, notifierKey{}, newBufferedNotifier(codec, notificationBufferSize))
}
s.codecsMu.Lock()
if atomic.LoadInt32(&s.run) != 1 { // server stopped
@ -275,7 +272,7 @@ func (s *Server) handle(ctx context.Context, codec ServerCodec, req *serverReque
if req.isUnsubscribe { // cancel subscription, first param must be the subscription id
if len(req.args) >= 1 && req.args[0].Kind() == reflect.String {
notifier, supported := ctx.Value(NotifierContextKey).(*bufferedNotifier)
notifier, supported := NotifierFromContext(ctx)
if !supported { // interface doesn't support subscriptions (e.g. http)
return codec.CreateErrorResponse(&req.id, &callbackError{ErrNotificationsUnsupported.Error()}), nil
}
@ -298,8 +295,8 @@ func (s *Server) handle(ctx context.Context, codec ServerCodec, req *serverReque
// active the subscription after the sub id was successful sent to the client
activateSub := func() {
notifier, _ := ctx.Value(NotifierContextKey).(*bufferedNotifier)
notifier.activate(subid)
notifier, _ := NotifierFromContext(ctx)
notifier.(*bufferedNotifier).activate(subid)
}
return codec.CreateResponse(req.id, subid), activateSub