accounts: use chan instead of wg in newBlockEvent

accounts/manager.go

@@ -40,8 +40,8 @@ type Config struct {
 // newBackendEvent lets the manager know it should
 // track the given backend for wallet updates.
 type newBackendEvent struct {
- backend Backend
- wg *sync.WaitGroup
+ backend  Backend
+ processed chan struct{} // Informs event emitter that backend has been integrated
 }
 
 // Manager is an overarching account manager that can communicate with various
@@ -107,15 +107,13 @@ func (am *Manager) Config() *Config {
 }
 
 // AddBackends starts the tracking of additional backends for wallet updates.
+// cmd/geth assumes once this func returns the backends have been already integrated.
 func (am *Manager) AddBackends(backends ...Backend) {
- var wg sync.WaitGroup
+ done := make(chan struct{}, len(backends))
  for _, backend := range backends {
- wg.Add(1)
- am.newBackends <- newBackendEvent{backend, &wg}
+ am.newBackends <- newBackendEvent{backend, done}
+ <-done
  }
- // cmd/geth assumes after the invocation of AddBackends
- // manager is already tracking those backends.
- wg.Wait()
 }
 
 // update is the wallet event loop listening for notifications from the backends
@@ -156,7 +154,7 @@ func (am *Manager) update() {
  kind := reflect.TypeOf(backend)
  am.backends[kind] = append(am.backends[kind], backend)
  am.lock.Unlock()
- event.wg.Done()
+ event.processed <- struct{}{}
  case errc := <-am.quit:
  // Manager terminating, return
  errc <- nil