Fix racing on route handler's indexes change

Author: franz1981

vertx-web/src/main/java/io/vertx/ext/web/impl/RouteState.java

@@ -1279,16 +1279,20 @@ boolean hasNextFailureHandler(RoutingContextImplBase context) {
     return context.currentRouteNextFailureHandlerIndex() < getFailureHandlersLength();
   }
 
-  void handleContext(RoutingContextImplBase context) {
-    contextHandlers
-      .get(context.currentRouteNextHandlerIndex() - 1)
-      .handle(context);
+  Handler<RoutingContext> nextContextHandler(RoutingContextImplBase context) {
+    int index = context.nextContextHandler(getContextHandlersLength());
+    if (index == -1) {
+      return null;
+    }
+    return contextHandlers.get(index - 1);
   }
 
-  void handleFailure(RoutingContextImplBase context) {
-    failureHandlers
-      .get(context.currentRouteNextFailureHandlerIndex() - 1)
-      .handle(context);
+  Handler<RoutingContext> nextFailureHandler(RoutingContextImplBase context) {
+    int index = context.nextFailureHandler(getFailureHandlersLength());
+    if (index == -1) {
+      return null;
+    }
+    return failureHandlers.get(index - 1);
   }
 
   public String getName() {

vertx-web/src/main/java/io/vertx/ext/web/impl/RoutingContextImplBase.java

@@ -130,18 +130,39 @@ void restart() {
     next();
   }
 
+  final int nextFailureHandler(int limit) {
+    int index;
+    do {
+      index = currentRouteNextFailureHandlerIndex;
+      if (index >= limit) {
+        return -1;
+      }
+    } while (!CURRENT_ROUTE_NEXT_FAILURE_HANDLER_INDEX.compareAndSet(this, index, index + 1));
+    return index;
+  }
+
+  final int nextContextHandler(int limit) {
+    int index;
+    do {
+      index = currentRouteNextHandlerIndex;
+      if (index >= limit) {
+        return -1;
+      }
+    } while (!CURRENT_ROUTE_NEXT_HANDLER_INDEX.compareAndSet(this, index, index + 1));
+    return index;
+  }
+
   boolean iterateNext() {
     boolean failed = failed();
     if (currentRoute != null) { // Handle multiple handlers inside route object
       try {
-        if (!failed && currentRoute.hasNextContextHandler(this)) {
-          CURRENT_ROUTE_NEXT_HANDLER_INDEX.incrementAndGet(this);
+        Handler<RoutingContext> handler;
+        if (!failed && (handler = currentRoute.nextContextHandler(this)) != null) {
           resetMatchFailure();
-          currentRoute.handleContext(this);
+          handler.handle(this);
           return true;
-        } else if (failed && currentRoute.hasNextFailureHandler(this)) {
-          CURRENT_ROUTE_NEXT_FAILURE_HANDLER_INDEX.incrementAndGet(this);
-          currentRoute.handleFailure(this);
+        } else if (failed && (handler = currentRoute.nextFailureHandler(this)) != null) {
+          handler.handle(this);
           return true;
         }
       } catch (Throwable t) {
@@ -169,12 +190,11 @@ boolean iterateNext() {
             if (LOG.isTraceEnabled()) {
               LOG.trace("Calling the " + (failed ? "failure" : "") + " handler");
             }
-            if (failed && currentRoute.hasNextFailureHandler(this)) {
-              CURRENT_ROUTE_NEXT_FAILURE_HANDLER_INDEX.incrementAndGet(this);
-              routeState.handleFailure(this);
-            } else if (currentRoute.hasNextContextHandler(this)) {
-              CURRENT_ROUTE_NEXT_HANDLER_INDEX.incrementAndGet(this);
-              routeState.handleContext(this);
+            Handler<RoutingContext> handler;
+            if (failed && (handler = currentRoute.nextFailureHandler(this)) != null) {
+              handler.handle(this);
+            } else if ((handler = currentRoute.nextContextHandler(this)) != null) {
+              handler.handle(this);
             } else {
               continue;
             }