rpc: refactor subscriptions and filters
This commit is contained in:
Bas van Kervel
committed by
Bas van Kervel
Bas van Kervel
parent
3b39d4d1c1
commit
47ff813012
@ -19,55 +19,104 @@ package downloader
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import (
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"sync"
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"golang.org/x/net/context"
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"github.com/ethereum/go-ethereum/event"
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"github.com/ethereum/go-ethereum/rpc"
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"golang.org/x/net/context"
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)
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// PublicDownloaderAPI provides an API which gives information about the current synchronisation status.
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// It offers only methods that operates on data that can be available to anyone without security risks.
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type PublicDownloaderAPI struct {
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d *Downloader
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mux *event.TypeMux
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muSyncSubscriptions sync.Mutex
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syncSubscriptions map[string]rpc.Subscription
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d *Downloader
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mux *event.TypeMux
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installSyncSubscription chan chan interface{}
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uninstallSyncSubscription chan *uninstallSyncSubscriptionRequest
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}
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// NewPublicDownloaderAPI create a new PublicDownloaderAPI.
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// NewPublicDownloaderAPI create a new PublicDownloaderAPI. The API has an internal event loop that
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// listens for events from the downloader through the global event mux. In case it receives one of
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// these events it broadcasts it to all syncing subscriptions that are installed through the
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// installSyncSubscription channel.
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func NewPublicDownloaderAPI(d *Downloader, m *event.TypeMux) *PublicDownloaderAPI {
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api := &PublicDownloaderAPI{d: d, mux: m, syncSubscriptions: make(map[string]rpc.Subscription)}
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api := &PublicDownloaderAPI{
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d: d,
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mux: m,
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installSyncSubscription: make(chan chan interface{}),
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uninstallSyncSubscription: make(chan *uninstallSyncSubscriptionRequest),
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}
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go api.run()
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go api.eventLoop()
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return api
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}
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func (api *PublicDownloaderAPI) run() {
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sub := api.mux.Subscribe(StartEvent{}, DoneEvent{}, FailedEvent{})
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// eventLoop runs an loop until the event mux closes. It will install and uninstall new
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// sync subscriptions and broadcasts sync status updates to the installed sync subscriptions.
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func (api *PublicDownloaderAPI) eventLoop() {
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var (
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sub = api.mux.Subscribe(StartEvent{}, DoneEvent{}, FailedEvent{})
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syncSubscriptions = make(map[chan interface{}]struct{})
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)
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for event := range sub.Chan() {
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var notification interface{}
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for {
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select {
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case i := <-api.installSyncSubscription:
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syncSubscriptions[i] = struct{}{}
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case u := <-api.uninstallSyncSubscription:
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delete(syncSubscriptions, u.c)
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close(u.uninstalled)
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case event := <-sub.Chan():
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if event == nil {
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return
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}
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switch event.Data.(type) {
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case StartEvent:
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result := &SyncingResult{Syncing: true}
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result.Status.Origin, result.Status.Current, result.Status.Height, result.Status.Pulled, result.Status.Known = api.d.Progress()
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notification = result
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case DoneEvent, FailedEvent:
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notification = false
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}
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api.muSyncSubscriptions.Lock()
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for id, sub := range api.syncSubscriptions {
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if sub.Notify(notification) == rpc.ErrNotificationNotFound {
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delete(api.syncSubscriptions, id)
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var notification interface{}
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switch event.Data.(type) {
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case StartEvent:
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result := &SyncingResult{Syncing: true}
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result.Status.Origin, result.Status.Current, result.Status.Height, result.Status.Pulled, result.Status.Known = api.d.Progress()
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notification = result
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case DoneEvent, FailedEvent:
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notification = false
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}
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// broadcast
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for c := range syncSubscriptions {
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c <- notification
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}
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}
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api.muSyncSubscriptions.Unlock()
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}
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}
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// Syncing provides information when this nodes starts synchronising with the Ethereum network and when it's finished.
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func (api *PublicDownloaderAPI) Syncing(ctx context.Context) (*rpc.Subscription, error) {
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notifier, supported := rpc.NotifierFromContext(ctx)
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if !supported {
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return &rpc.Subscription{}, rpc.ErrNotificationsUnsupported
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}
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rpcSub := notifier.CreateSubscription()
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go func() {
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statuses := make(chan interface{})
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sub := api.SubscribeSyncStatus(statuses)
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for {
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select {
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case status := <-statuses:
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notifier.Notify(rpcSub.ID, status)
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case <-rpcSub.Err():
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sub.Unsubscribe()
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return
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case <-notifier.Closed():
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sub.Unsubscribe()
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return
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}
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}
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}()
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return rpcSub, nil
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}
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// Progress gives progress indications when the node is synchronising with the Ethereum network.
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type Progress struct {
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Origin uint64 `json:"startingBlock"`
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@ -83,26 +132,42 @@ type SyncingResult struct {
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Status Progress `json:"status"`
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}
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// Syncing provides information when this nodes starts synchronising with the Ethereum network and when it's finished.
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func (api *PublicDownloaderAPI) Syncing(ctx context.Context) (rpc.Subscription, error) {
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notifier, supported := rpc.NotifierFromContext(ctx)
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if !supported {
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return nil, rpc.ErrNotificationsUnsupported
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}
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subscription, err := notifier.NewSubscription(func(id string) {
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api.muSyncSubscriptions.Lock()
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delete(api.syncSubscriptions, id)
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api.muSyncSubscriptions.Unlock()
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})
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if err != nil {
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return nil, err
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}
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api.muSyncSubscriptions.Lock()
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api.syncSubscriptions[subscription.ID()] = subscription
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api.muSyncSubscriptions.Unlock()
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return subscription, nil
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// uninstallSyncSubscriptionRequest uninstalles a syncing subscription in the API event loop.
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type uninstallSyncSubscriptionRequest struct {
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c chan interface{}
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uninstalled chan interface{}
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}
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// SyncStatusSubscription represents a syncing subscription.
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type SyncStatusSubscription struct {
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api *PublicDownloaderAPI // register subscription in event loop of this api instance
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c chan interface{} // channel where events are broadcasted to
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unsubOnce sync.Once // make sure unsubscribe logic is executed once
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}
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// Unsubscribe uninstalls the subscription from the DownloadAPI event loop.
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// The status channel that was passed to subscribeSyncStatus isn't used anymore
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// after this method returns.
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func (s *SyncStatusSubscription) Unsubscribe() {
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s.unsubOnce.Do(func() {
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req := uninstallSyncSubscriptionRequest{s.c, make(chan interface{})}
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s.api.uninstallSyncSubscription <- &req
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for {
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select {
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case <-s.c:
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// drop new status events until uninstall confirmation
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continue
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case <-req.uninstalled:
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return
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}
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}
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})
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}
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// SubscribeSyncStatus creates a subscription that will broadcast new synchronisation updates.
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// The given channel must receive interface values, the result can either
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func (api *PublicDownloaderAPI) SubscribeSyncStatus(status chan interface{}) *SyncStatusSubscription {
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api.installSyncSubscription <- status
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return &SyncStatusSubscription{api: api, c: status}
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}
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