fix error handling for async predicate

Signed-off-by: tassoc <claudio.tasso@tasgroup.eu>

Author: tassoc

spring-cloud-gateway-server/src/main/java/org/springframework/cloud/gateway/handler/RoutePredicateHandlerMapping.java

@@ -131,24 +131,18 @@ protected Mono<Route> lookupRoute(ServerWebExchange exchange) {
 return this.routeLocator.getRoutes().filterWhen(route -> {
 // add the current route we are testing
 exchange.getAttributes().put(GATEWAY_PREDICATE_ROUTE_ATTR, route.getId());
-try {
-return route.getPredicate().apply(exchange);
-}
-catch (Exception e) {
+
+return Mono.defer(() -> Mono.from(route.getPredicate().apply(exchange))).onErrorResume(e -> {
 logger.error("Error applying predicate for route: " + route.getId(), e);
-}
-return Mono.just(false);
-})
-.next()
-// TODO: error handling
-.map(route -> {
-if (logger.isDebugEnabled()) {
-logger.debug("Route matched: " + route.getId());
-}
-validateRoute(route, exchange);
-return route;
+return Mono.just(false);
 });
-
+}).next().map(route -> {
+if (logger.isDebugEnabled()) {
+logger.debug("Route matched: " + route.getId());
+}
+validateRoute(route, exchange);
+return route;
+});
 /*
  * TODO: trace logging if (logger.isTraceEnabled()) {
  * logger.trace("RouteDefinition did not match: " + routeDefinition.getId()); }

spring-cloud-gateway-server/src/test/java/org/springframework/cloud/gateway/handler/RoutePredicateHandlerMappingTests.java

@@ -74,6 +74,11 @@ public void lookupRouteFromAsyncPredicates(CapturedOutput capturedOutput) {
 .uri("http://localhost")
 .asyncPredicate(swe -> Mono.just(boom1()))
 .build();
+Route routeMonoError = Route.async()
+.id("routeMonoError")
+.uri("http://localhost")
+.asyncPredicate(swe -> Mono.error(new IllegalStateException("boom3")))
+.build();
 Route routeFail = Route.async().id("routeFail").uri("http://localhost").asyncPredicate(swe -> {
 throw new IllegalStateException("boom2");
 }).build();
@@ -82,7 +87,8 @@ public void lookupRouteFromAsyncPredicates(CapturedOutput capturedOutput) {
 .uri("http://localhost")
 .asyncPredicate(swe -> Mono.just(true))
 .build();
-RouteLocator routeLocator = () -> Flux.just(routeFalse, routeError, routeFail, routeTrue).hide();
+RouteLocator routeLocator = () -> Flux.just(routeFalse, routeError, routeMonoError, routeFail, routeTrue)
+.hide();
 RoutePredicateHandlerMapping mapping = new RoutePredicateHandlerMapping(null, routeLocator,
 new GlobalCorsProperties(), new MockEnvironment());
 
@@ -95,6 +101,9 @@ public void lookupRouteFromAsyncPredicates(CapturedOutput capturedOutput) {
 
 assertThat(capturedOutput.getOut().contains("Error applying predicate for route: routeFail")).isTrue();
 assertThat(capturedOutput.getOut().contains("java.lang.IllegalStateException: boom2")).isTrue();
+
+assertThat(capturedOutput.getOut().contains("Error applying predicate for route: routeMonoError")).isTrue();
+assertThat(capturedOutput.getOut().contains("java.lang.IllegalStateException: boom3")).isTrue();
 }
 
 boolean boom1() {