Add ExecutionLimit property to break loops

libraries/botbuilder-dialogs-adaptive/src/conditions/onError.ts

@@ -5,19 +5,25 @@
  * Copyright (c) Microsoft Corporation. All rights reserved.
  * Licensed under the MIT License.
  */
-import { Dialog } from 'botbuilder-dialogs';
+import { Dialog, TurnPath } from 'botbuilder-dialogs';
 import { OnDialogEvent } from './onDialogEvent';
 import { ActionContext } from '../actionContext';
 import { AdaptiveEvents } from '../adaptiveEvents';
 import { ActionChangeList } from '../actionChangeList';
 import { ActionChangeType } from '../actionChangeType';
+import { NumberExpression } from 'adaptive-expressions';
 
 /**
  * Actions triggered when an error event has been emitted.
  */
 export class OnError extends OnDialogEvent {
     static $kind = 'Microsoft.OnError';
 
+    /**
+     * Gets or sets the number of executions allowed. Used to avoid infinite loops in case of error (OPTIONAL).
+     */
+    executionLimit: NumberExpression = new NumberExpression(0);
+
     /**
      * Initializes a new instance of the [OnError](xref:botbuilder-dialogs-adaptive.OnError) class.
      *
@@ -28,6 +34,20 @@ export class OnError extends OnDialogEvent {
         super(AdaptiveEvents.error, actions, condition);
     }
 
+    /**
+     * Method called to execute the condition's actions.
+     *
+     * @param actionContext Context.
+     * @returns A promise with plan change list.
+     */
+    async execute(actionContext: ActionContext): Promise<ActionChangeList[]> {
+        const limit = this.currentExecutionLimit();
+
+        actionContext.state.setValue(TurnPath.executionLimit, limit);
+
+        return await super.execute(actionContext);
+    }
+
     /**
      * Called when a change list is created.
      *
@@ -43,4 +63,12 @@ export class OnError extends OnDialogEvent {
         changeList.changeType = ActionChangeType.replaceSequence;
         return changeList;
     }
+
+    currentExecutionLimit = function (): number {
+        if (this.executionLimit > 0) {
+            return this.executionLimit;
+        }
+        //10 is the default number of executions we'll allow before breaking the loop.
+        return 10;
+    };
 }

libraries/botbuilder-dialogs/src/dialogHelper.ts

@@ -94,15 +94,29 @@ export async function internalRun(
     // or we have had an exception AND there was an OnError action which captured the error. We need to continue the
     // turn based on the actions the OnError handler introduced.
     let endOfTurn = false;
+    let errorHandlerCalled = 0;
+    const TURN_STATE = 'turn';
+
     while (!endOfTurn) {
         try {
             dialogTurnResult = await innerRun(context, dialogId, dialogContext);
 
             // turn successfully completed, break the loop
             endOfTurn = true;
         } catch (err) {
+            errorHandlerCalled++;
+
             // fire error event, bubbling from the leaf.
-            const handled = await dialogContext.emitEvent(DialogEvents.error, err, true, true);
+            let handled = await dialogContext.emitEvent(DialogEvents.error, err, true, true);
+
+            let executionLimit = 0;
+            executionLimit = context.turnState.get(TURN_STATE).executionLimit;
+
+            if (executionLimit > 0 && errorHandlerCalled > executionLimit) {
+                // if the errorHandler has being called multiple times, there's an error inside the onError.
+                // We should throw the exception and break the loop.
+                handled = false;
+            }
 
             if (!handled) {
                 // error was NOT handled, throw the exception and end the turn.

libraries/botbuilder-dialogs/src/memory/turnPath.ts

@@ -45,4 +45,7 @@ export class TurnPath {
 
     /// This is a bool which if set means that the turncontext.activity has been consumed by some component in the system.
     static readonly activityProcessed = 'turn.activityProcessed';
+
+    /// Used to limit the execution of a trigger avoiding infinite loops in case of errors.
+    static readonly executionLimit = 'turn.executionLimit';
 }