[enh] don't repeatedly alert about a failed state

src/lib/types/state.ts

@@ -1,20 +1,25 @@
 export class Watcher {
     private _state: 'INIT'|'OK'|'FAILURE'|'RECOVERED'
+    private _stateChanged: boolean
     private _error?: any
 
     constructor(public readonly name: string) {
+        this._stateChanged = false
         this._state = "INIT"
     }
 
     public stateOK() {
+        this._stateChanged = this._state !== "OK"
         this._state = "OK"
     }
 
     public stateRecovered() {
+        this._stateChanged = this._state !== "RECOVERED"
         this._state = "RECOVERED"
     }
 
     public stateFailure(error: any) {
+        this._stateChanged = this._state !== "FAILURE"
         this._state = "FAILURE"
         this._error = error
     }
@@ -23,6 +28,10 @@ export class Watcher {
         return this._state
     }
 
+    public get stateChanged() {
+        return this._stateChanged
+    }
+
     public get error() {
         return this._error
     }

src/lib/watcherLoop.ts

@@ -47,7 +47,10 @@ export function watcherLoop(
       }
       // Wait before reconnecting
       const waitingDelay = reconnectionDelays[Math.min(reconnectionDelays.length - 1, i)]
+      if (watcher.stateChanged) {
+        // Notify only if state changed since
         await onDisconnection(waitingDelay, watcher.error)
+      }
       await new Promise(resolve => setTimeout(resolve, waitingDelay))
       i++
     }