WebFlux filter: Flux access redis,if ok then run next filter,But unconformity - spring-webflux

Question

In project,I verify the app_key is valid by pass redis.
I use ReactiveRedisTemplate to access redis data，and in filter I verify the app_key is valid.if the app_key is valid,then jump to next filter,else output to client the exception.
Actually：if redis connection timeout，ex should be runnig.but when the redis running normal ,the program is not exec verfiy app_key ,It direct jump to next filter.
Please tell me how do,Thanks!
#Resource
private AppKeyProvider appKeyProvider;
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
try {
String app_key =exchange.getRequest().getQueryParams().getFirst("app_key"));
//app_key verify
Flux.just(app_key).flatMap(key -> appKeyProvider.getAppKey(key)).subscribe(
appKey -> {
if (appKey == null) {
//app_key is not valid
throw new AppException(ErrorCode.ILLEGAL_APP_KEY);
}else{
//do... jump to next filter
}
},
ex -> {
throw new AppException(ErrorCode.SERVICE_BASIC_ERROR, ex);
}
);
} catch (AppException ex) {
exchange.getResponse().setStatusCode(HttpStatus.BAD_REQUEST);
exchange.getResponse().getHeaders().setContentType(MediaType.APPLICATION_JSON);
String result = RestHelper.build(ex, exchange).toString();
return exchange.getResponse().writeWith(Mono.just(exchange.getResponse().bufferFactory().wrap(result.getBytes(Charsets.UTF_8))));
}
return chain.filter(exchange);
}
AppKeyProvider.java
#Component
public class AppKeyProvider {
#Resource
private ReactiveRedisTemplate reactiveRedisTemplate;
private final static Logger logger = LoggerFactory.getLogger(AppKeyProvider.class);
private final static AppKeyProvider instance = new AppKeyProvider();
private static ConcurrentHashMap<String, Api> apiMap = new ConcurrentHashMap<String, Api>();
private final static Lock lock = new ReentrantLock(true);
/**
* Get AppKey
*
* #param app_key
* #return
*/
public Mono<AppKey> getAppKey(String app_key) {
ReactiveValueOperations<String, AppKey> operations = reactiveRedisTemplate.opsForValue();
Mono<AppKey> appKey = operations.get(RedisKeypPrefix.APP_KEY + app_key);
return appKey;
}
}

Answer 1

This happens because you've manually subscribed to the key lookup part. Doing so decouples the main filter processing from that operation, meaning they can happen concurrently in different threads - so they can't track each others' result.
Also, in reactive programming errors happen within the pipeline and should be dealt with operators; try/catch blocks won't work in this case.
Here's an attempt at fixing this code snippet:
public Mono<Void> filter(ServerWebExchange exchange, GatewayFilterChain chain) {
String app_key = exchange.getRequest().getQueryParams().getFirst("app_key"));
return appKeyProvider.getAppKey(app_key)
.switchOnEmpty(Mono.error(new AppException(ErrorCode.ILLEGAL_APP_KEY)))
.flatMap(key -> chain.filter(exchange))
.onErrorResume(AppException.class, exc -> {
exchange.getResponse().setStatusCode(HttpStatus.BAD_REQUEST);
exchange.getResponse().getHeaders().setContentType(MediaType.APPLICATION_JSON);
String result = RestHelper.build(ex, exchange).toString();
return exchange.getResponse().writeWith(Mono.just(exchange.getResponse().bufferFactory().wrap(result.getBytes(Charsets.UTF_8))));
});
}