We have rest api application. We use redis for API response caching and internal method caching. If redis connection then it is making our API down. We want to bypass the redis caching if that redis connection fails or any exception instead of making our API down.
There is a interface CacheErrorHandler but it handles the redis get set operation failures not redis connection problems. We are using Spring 4.1.2.
Let's boil this down a bit. Your application uses caching (implemented with Redis). If the Redis connection is stale/closed or otherwise, then you want the application to bypass caching and (presumably) go directly to an underlying data store (e.g. RDBMS). The application Service logic might look similar to...
#Service
class CustomerService ... {
#Autowired
private CustomerRepository customerRepo;
protected CustomerRepository getCustomerRepo() {
Assert.notNull(customerRepo, "The CustomerRepository was not initialized!");
return customerRepo;
}
#Cacheable(value = "Customers")
public Customer getCustomer(Long customerId) {
return getCustomerRepo().load(customerId);
}
...
}
All that matters in Spring core's Caching Abstraction to ascertain a Cache "miss" is that the value returned is null. As such, Spring Caching Infrastructure will then proceed in calling the actual Service method (i.e. getCustomer). Keep in mind on the return of the getCustomerRepo().load(customerId) call, you also need to handle the case where Spring's Caching Infrastructure attempts to now cache the value.
In the spirit of keeping it simple, we will do without AOP, but you should be able to achieve this using AOP as well (your choice).
All you (should) need is a "custom" RedisCacheManager extending the SDR CacheManager implementation, something like...
package example;
import org.springframework.cache.Cache;
import org.springframework.data.redis.cache.RedisCacheManager;
...
class MyCustomRedisCacheManager extends RedisCacheManager {
public MyCustomerRedisCacheManager(RedisTemplate redisTemplate) {
super(redisTemplate);
}
#Override
public Cache getCache(String name) {
return new RedisCacheWrapper(super.getCache(name));
}
protected static class RedisCacheWrapper implements Cache {
private final Cache delegate;
public RedisCacheWrapper(Cache redisCache) {
Assert.notNull(redisCache, "'delegate' must not be null");
this.delegate = redisCache;
}
#Override
public Cache.ValueWrapper get(Object key) {
try {
delegate.get(key);
}
catch (Exception e) {
return handleErrors(e);
}
}
#Override
public void put(Object key, Object value) {
try {
delegate.put(key, value);
}
catch (Exception e) {
handleErrors(e);
}
}
// implement clear(), evict(key), get(key, type), getName(), getNativeCache(), putIfAbsent(key, value) accordingly (delegating to the delegate).
protected <T> T handleErrors(Exception e) throws Exception {
if (e instanceof <some RedisConnection Exception type>) {
// log the connection problem
return null;
}
else if (<something different>) { // act appropriately }
...
else {
throw e;
}
}
}
}
So, if Redis is unavailable, perhaps the best you can do is log the problem and proceed to let the Service invocation happen. Clearly, this will hamper performance but at least it will raise awareness that a problem exists. Clearly, this could be tied into a more robust notification system, but it is a crude example of the possibilities. The important thing is, your Service remains available while the other services (e.g. Redis) that the application service depends on, may have failed.
In this implementation (vs. my previous explanation) I chose to delegate to the underlying, actual RedisCache implementation to let the Exception occur, then knowing full well a problem with Redis exists, and so that you can deal with the Exception appropriately. However, if you are a certain that the Exception is related to a connection problem upon inspection, you can return "null" to let Spring Caching Infrastructure proceed as if it were a Cache "miss" (i.e. bad Redis Connection == Cache miss, in this case).
I know something like this should help your problem as I built a similar prototype of a "custom" CacheManager implementation for GemFire and one of Pivotal's customers. In that particular UC, the Cache "miss" had to be triggered by an "out-of-date version" of the application domain object where production had a mix of newer and older application clients connecting to GemFire through Spring's Caching Abstraction. The application domain object fields would change in newer versions of the app for instance.
Anyway, hope this helps or gives you more ideas.
Cheers!
So, I was digging through the core Spring Framework Caching Abstraction source today addressing another question and it seems if a CacheErrorHandler is implemented properly, then perhaps a problematic Redis Connection could still result in the desired behavior, e.g. cache "miss" (triggered with the return of a null value).
See the AbstractCacheInvoker source for more details.
The cache.get(key) should result in an exception due to a faulty Redis Connection and thus Exception handler would be invoked...
catch (RuntimeException e) {
getErrorHandler().handleCacheGetError(e, cache, key);
return null; // If the exception is handled, return a cache miss
}
If the CacheErrorHandler properly handles the Cache "get" error (and does not re-throw the/an Exception), then a null value will be returned indicating a cache "miss".
Thank you #John Blum. My solution in Spring Boot is as follows.
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.cache.Cache;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.core.RedisOperations;
import org.springframework.util.Assert;
import java.util.concurrent.Callable;
class CustomRedisCacheManager extends RedisCacheManager {
private static Logger logger = LoggerFactory.getLogger(CustomRedisCacheManager.class);
public CustomRedisCacheManager(RedisOperations redisOperations) {
super(redisOperations);
}
#Override
public Cache getCache(String name) {
return new RedisCacheWrapper(super.getCache(name));
}
protected static class RedisCacheWrapper implements Cache {
private final Cache delegate;
public RedisCacheWrapper(Cache redisCache) {
Assert.notNull(redisCache, "delegate cache must not be null");
this.delegate = redisCache;
}
#Override
public String getName() {
try {
return delegate.getName();
} catch (Exception e) {
return handleException(e);
}
}
#Override
public Object getNativeCache() {
try {
return delegate.getNativeCache();
} catch (Exception e) {
return handleException(e);
}
}
#Override
public Cache.ValueWrapper get(Object key) {
try {
return delegate.get(key);
} catch (Exception e) {
return handleException(e);
}
}
#Override
public <T> T get(Object o, Class<T> aClass) {
try {
return delegate.get(o, aClass);
} catch (Exception e) {
return handleException(e);
}
}
#Override
public <T> T get(Object o, Callable<T> callable) {
try {
return delegate.get(o, callable);
} catch (Exception e) {
return handleException(e);
}
}
#Override
public void put(Object key, Object value) {
try {
delegate.put(key, value);
} catch (Exception e) {
handleException(e);
}
}
#Override
public ValueWrapper putIfAbsent(Object o, Object o1) {
try {
return delegate.putIfAbsent(o, o1);
} catch (Exception e) {
return handleException(e);
}
}
#Override
public void evict(Object o) {
try {
delegate.evict(o);
} catch (Exception e) {
handleException(e);
}
}
#Override
public void clear() {
try {
delegate.clear();
} catch (Exception e) {
handleException(e);
}
}
private <T> T handleException(Exception e) {
logger.error("handleException", e);
return null;
}
}
}
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.cache.RedisCacheManager;
import org.springframework.data.redis.core.RedisTemplate;
#Configuration
public class RedisConfig {
#Bean
public RedisCacheManager redisCacheManager(RedisTemplate redisTemplate) {
CustomRedisCacheManager redisCacheManager = new CustomRedisCacheManager(redisTemplate);
redisCacheManager.setUsePrefix(true);
return redisCacheManager;
}
}
actually my response is directed to Mr. #Vivek Aditya - I faced the same problem: new spring-data-redis api and not constructing RedisCacheManager per RedisTemplate. The only option - based on #John Blum suggestions - was to use aspects. And below is my code.
#Aspect
#Component
public class FailoverRedisCacheAspect {
private static class FailoverRedisCache extends RedisCache {
protected FailoverRedisCache(RedisCache redisCache) {
super(redisCache.getName(), redisCache.getNativeCache(), redisCache.getCacheConfiguration());
}
#Override
public <T> T get(Object key, Callable<T> valueLoader) {
try {
return super.get(key, valueLoader);
} catch (RuntimeException ex) {
return valueFromLoader(key, valueLoader);
}
}
private <T> T valueFromLoader(Object key, Callable<T> valueLoader) {
try {
return valueLoader.call();
} catch (Exception e) {
throw new ValueRetrievalException(key, valueLoader, e);
}
}
}
#Around("execution(* org.springframework.cache.support.AbstractCacheManager.getCache (..))")
public Cache beforeSampleCreation(ProceedingJoinPoint proceedingJoinPoint) {
try {
Cache cache = (Cache) proceedingJoinPoint.proceed(proceedingJoinPoint.getArgs());
if (cache instanceof RedisCache) {
return new FailoverRedisCache((RedisCache) cache);
} else {
return cache;
}
} catch (Throwable ex) {
return null;
}
}
}
works fine for all reasonable scenarios:
app starts fine with redis down
app (still) works during (sudden) redis outage
when redis starts working again, app sees it
Edit: the code is more like a poc - only for "get", and I don't like reinstantiating FailoverRedisCache every single cache hit - there should be a map.
None of the above worked for us when using Spring Boot 2.3.9.release with Redis. We ended up creating and registering our own customized CacheErrorHandler named CustomCacheErrorHandler to override the default SimpleCacheErrorHandler provided by Spring Framework. This will work perfectly.
#Configuration
public class CachingConfiguration extends CachingConfigurerSupport {
#Override
public CacheErrorHandler errorHandler() {
return new CustomCacheErrorHandler();
}
}
class CustomCacheErrorHandler implements CacheErrorHandler {
Logger log = Logger.get(CustomCacheErrorHandler.class);
#Override
public void handleCacheGetError(RuntimeException e, Cache cache, Object o) {
log.error(e.getMessage(), e);
}
#Override
public void handleCachePutError(RuntimeException e, Cache cache, Object o, Object o1) {
log.error(e.getMessage(), e);
}
#Override
public void handleCacheEvictError(RuntimeException e, Cache cache, Object o) {
log.error(e.getMessage(), e);
}
#Override
public void handleCacheClearError(RuntimeException e, Cache cache) {
log.error(e.getMessage(), e);
}
}
I had same problem, but, unfortunately, none of the above solutions work for me. I checked for the problem and found out that the executed command never timed out if there was no connection to Redis. So I start to study lettuce library for a solution. I solve the problem by rejecting the command when there is no connection:
#Bean
public LettuceConnectionFactory lettuceConnectionFactory()
{
final SocketOptions socketOptions = SocketOptions.builder().connectTimeout(Duration.ofSeconds(10)).build();
ClientOptions clientOptions = ClientOptions.builder()
.socketOptions(socketOptions)
.autoReconnect(true)
.disconnectedBehavior(ClientOptions.DisconnectedBehavior.REJECT_COMMANDS)
.build();
LettuceClientConfiguration clientConfig = LettuceClientConfiguration.builder()
.commandTimeout(Duration.ofSeconds(10))
.clientOptions(clientOptions).build();
RedisStandaloneConfiguration redisStandaloneConfiguration = new RedisStandaloneConfiguration(this.host, this.port);
return new LettuceConnectionFactory(redisStandaloneConfiguration, clientConfig);
}
All the core Spring Framework Cache abstraction annotations (e.g. #Cacheable) along with the JSR-107 JCache annotations supported by the core SF delegate to the underlying CacheManager under-the-hood, and for Redis, that is the RedisCacheManager.
You would configure the RedisCacheManager in Spring XML configuration meta-data similar to here.
One approach would be to write an AOP Proxy for the (Redis)CacheManager that uses the RedisConnection (indirectly from the RedisTemplate) to ascertain the state of the connection on each (Redis)CacheManger operation.
If the connection has failed, or is closed, for standard cache ops, the (Redis)CacheManager could return an instance of RedisCache for getCache(String name) that always returns null (indicating a Cache miss on an entry), thus passing through to the underlying data store.
There maybe better ways to handle this as I am not an expert on all things Redis (or SDR), but this should work and perhaps give you a few ides of your own.
Cheers.
You can use CacheErrorHandler. But you should make sure to make
RedisCacheManager transactionAware to false in your Redis Cache Config(to make sure the transaction is committed early when executing the caching part and the error is caught by CacheErrorHandler and don't wait until the end of the execution which skips CacheErrorHandler part). The function to set transactionAware to false looks like this:
#Bean
public RedisCacheManager redisCacheManager(LettuceConnectionFactory lettuceConnectionFactory) {
JdkSerializationRedisSerializer redisSerializer = new JdkSerializationRedisSerializer(getClass().getClassLoader());
RedisCacheConfiguration redisCacheConfiguration = RedisCacheConfiguration.defaultCacheConfig()
.entryTtl(Duration.ofHours(redisDataTTL))
.serializeValuesWith(RedisSerializationContext.SerializationPair.fromSerializer(redisSerializer));
redisCacheConfiguration.usePrefix();
RedisCacheManager redisCacheManager = RedisCacheManager.RedisCacheManagerBuilder.fromConnectionFactory(lettuceConnectionFactory)
.cacheDefaults(redisCacheConfiguration)
.build();
redisCacheManager.setTransactionAware(false);
return redisCacheManager;
}
I have a spring boot application that uses the libraries: SimpleMessageListenerContainer (https://docs.spring.io/spring-amqp/docs/current/api/org/springframework/amqp/rabbit/listener/SimpleMessageListenerContainer.html) and SimpleMessageListenerContainerFactory (https://www.javadoc.io/static/org.springframework.cloud/spring-cloud-aws-messaging/2.2.0.RELEASE/org/springframework/cloud/aws/messaging/config/SimpleMessageListenerContainerFactory.html). The application uses ASW SQS and Kafka but I'm experiencing some out of order data and trying to investigate why. Is there a way to view logging from the libraries? I know I cannot edit them directly but when I create the bean, I want to be able to see the logs from those two libraries and if possible to add to them.
Currently I'm setting up the bean in this way:
#ConditionalOnProperty(value = "application.listener-mode", havingValue = "SQS")
#Component
public class SqsConsumer {
private final static Logger logger = LoggerFactory.getLogger(SqsConsumer.class);
#Autowired
private ConsumerMessageHandler consumerMessageHandler;
#Autowired
private KafkaProducer producer;
#PostConstruct
public void init() {
logger.info("Loading SQS Listener Bean");
}
#SqsListener("${application.aws-iot.sqs-url}")
public void receiveMessage(String message) {
byte[] decodedValue = Base64.getDecoder().decode(message);
consumerMessageHandler.handle(decodedValue, message);
}
#Bean
public SimpleMessageListenerContainerFactory simpleMessageListenerContainerFactory(AmazonSQSAsync amazonSqs) {
SimpleMessageListenerContainerFactory factory = new SimpleMessageListenerContainerFactory();
factory.setAmazonSqs(amazonSqs);
factory.setMaxNumberOfMessages(10);
factory.setWaitTimeOut(20);
logger.info("Created simpleMessageListenerContainerFactory");
logger.info(factory.toString());
return factory;
}
}
For reference, this is a method in the SimpleMessageListenerContainer. It is these logs which I would like to investigate and potentially add to:
#Override
public void run() {
while (isQueueRunning()) {
try {
ReceiveMessageResult receiveMessageResult = getAmazonSqs()
.receiveMessage(
this.queueAttributes.getReceiveMessageRequest());
CountDownLatch messageBatchLatch = new CountDownLatch(
receiveMessageResult.getMessages().size());
for (Message message : receiveMessageResult.getMessages()) {
if (isQueueRunning()) {
MessageExecutor messageExecutor = new MessageExecutor(
this.logicalQueueName, message, this.queueAttributes);
getTaskExecutor().execute(new SignalExecutingRunnable(
messageBatchLatch, messageExecutor));
}
else {
messageBatchLatch.countDown();
}
}
try {
messageBatchLatch.await();
}
catch (InterruptedException e) {
Thread.currentThread().interrupt();
}
}
catch (Exception e) {
getLogger().warn(
"An Exception occurred while polling queue '{}'. The failing operation will be "
+ "retried in {} milliseconds",
this.logicalQueueName, getBackOffTime(), e);
try {
// noinspection BusyWait
Thread.sleep(getBackOffTime());
}
catch (InterruptedException ie) {
Thread.currentThread().interrupt();
}
}
}
SimpleMessageListenerContainer.this.scheduledFutureByQueue
.remove(this.logicalQueueName);
}
How would I be able to see all of that logging from where I create the bean?
Any help would be much appreciated!
I have a question about initializing data in Spring-Boot.
I have this :
#PostConstruct
public void run() {
try {
upload(path);
logger.info("Seeding dictionary database...");
} catch (IOException e) {
//.....
}
}
run() method read .json file and fills the database with information from the file when the app starts. But I also have a .sql file that also fills the database when starts. The table created from initialization from the .sql file is related to the table created from the .json file
When app starts i have
INSERT INTO "USER_DICTIONARY"("DICTIONARY_ID", "USER_ID") VALUES (1, 0)
I have this line in my import.sql but this causes errors because DICTIONARY_ID doesn't exist jet because it comes from .json file which is loaded after import.sql
The data retrieved from the .json file is needed to correctly map this table when the sql file is executing.
Is it possible to execute my run() methody before executing .sql file, or can it be solved in some other way ? If so, please help me find the answer.
One option to seed a database is to use the CommandLineRunner in Spring Boot.
Example:
#Component
public class UserDataLoader implements CommandLineRunner {
#Autowired
UserRepository userRepository;
#Override
public void run(String... args) throws Exception {
loadUserData();
}
private void loadUserData() {
if (userRepository.count() == 0) {
User user1 = new User("John", "Doe");
User user2 = new User("John", "Cook");
userRepository.save(user1);
userRepository.save(user2);
}
System.out.println(userRepository.count());
}
}
The CommandRunner interface will execute just after the application starts.
Another way is is to use a #EventListener that listens to the application’s ContextRefreshEvent.
Example:
#Component
public class DBSeed {
#EventListener
public void seed(ContextRefreshedEvent event) {
try {
upload(path);
logger.info("Seeding dictionary database...");
} catch (IOException e) {
//.....
}
}
}
I am developping an application using spring boot as framework. I have 2 methods the first one is deleting data from the database and the other one is deleting folder from the disk, so if i delete from the database and i can't delete from the disc all the operation will fail. So how can i do that with springboot ?
#Override
public ResponseEntity<?> delete(Long id) {
return libelleRepository.findById(id).map(libelle -> {
libelleRepository.delete(libelle);
return ResponseEntity.ok().build();
}).orElseThrow(() -> new GeneralResourceNotFoundException("Libelle not found with id " + id));
}
You can use the Spring's #Transactional for doing this.
Here is the sample code what I have tried. It performs a Database operation followed by a file operation in my example I'm trying to create a file. First am creating the file before performing the database operation and used TransactionSynchronizationAdapter to make sure the transaction is complete before commiting.
Code:
#Autowired
private UserService userService;
#Transactional
public String doFileOperation() {
File testFile = new File("C:\\test.txt");
TxnListener transactionListener = new TxnListener(testFile);
TransactionSynchronizationManager.registerSynchronization(transactionListener);
// DB Operation
userService.addUser();
// File Operation
List<String> lines = Arrays.asList("1st line", "2nd line");
try {
Files.write(Paths.get(testFile.getPath()),
lines,
StandardCharsets.UTF_8,
StandardOpenOption.CREATE,
StandardOpenOption.APPEND);
} catch (IOException e) {
e.printStackTrace();
}
return "";
}
public class TxnListener extends TransactionSynchronizationAdapter {
private File outputFile;
public TxnListener(File outputFile) {
this.outputFile = outputFile;
}
#Override
public void afterCompletion(int status) {
if (STATUS_COMMITTED != status) {
if (outputFile.exists()) {
if (!outputFile.delete()) {
System.out.println("Could not delete File" + outputFile.getPath() + " after failed transaction");
}
}
}
}
}
In case of exception during the Database operation afterCompletion will be called and the file will be deleted.
This way you can maintain the atomicity of the operation.
My app is built upon Spring + SockJs. Main page represents a table of available connections so that user can monitor them in real-time. Every single url monitor can be suspended/resumed separatelly from each other. The problem is once you suspend some monitor then you can never resume it back because ApplicationEvents property of MonitoringFacade bean suddenly becomes null for the SINGLE entity. For other entites listener keeps working pretty well. When attempt to invoke methods of such null listener NullPointerException is never thrown though.
class IndexController implements ApplicationEvents
...
public IndexController(SimpMessagingTemplate simpMessagingTemplate, MonitoringFacade monitoringFacade) {
this.simpMessagingTemplate = simpMessagingTemplate;
this.monitoringFacade = monitoringFacade;
}
#PostConstruct
public void initialize() {
if (logger.isDebugEnabled()) {
logger.debug(">>Index controller initialization.");
}
monitoringFacade.addDispatcher(this);
}
...
#Override
public void monitorUpdated(String monitorId) {
if (logger.isDebugEnabled()) {
logger.debug(">>Sending monitoring data to client with monitor id " + monitorId);
}
try {
ConfigurationDTO config = monitoringFacade.findConfig(monitorId);
Report report = monitoringFacade.findReport(monitorId);
ReportReadModel readModel = ReportReadModel.mapFrom(config, report);
simpMessagingTemplate.convertAndSend("/client/update", readModel);
} catch (Exception e) {
logger.log(Level.ERROR, "Exception: ", e);
}
}
public class MonitoringFacadeImpl implements MonitoringFacade
...
private ApplicationEvents dispatcher;
public void addDispatcher(ApplicationEvents dispatcher) {
logger.info("Setting up dispatcher");
this.dispatcher = dispatcher;
}
...
#Override
public void refreshed(RefreshEvent event) {
final String monitorId = event.getId().getIdentity();
if (logger.isDebugEnabled()) {
logger.debug(String.format(">>Refreshing monitoring data with monitor id '%s'", monitorId));
}
Configuration refreshedConfig = configurationService.find(monitorId);
reportingService.compileReport(refreshedConfig, event.getData());
if (logger.isDebugEnabled()) {
logger.debug(String.format(">>Notifying monitoring data updated with monitor id '%s'", monitorId) + dispatcher);
}
dispatcher.monitorUpdated(monitorId); // here dispatcher has null value... or it's actually not
}
void refreshed(RefreshEvent event) method succesfully receives updates from Quartz scheduler through the interface and sends it back to controller.
The question is how a singleton-scoped bean can have different property values for different objects it is applied for and why such a property becomes null even though i have never set it to null?
UPD:
#MessageMapping("/monitor/{monitorId}/suspend")
public void handleSuspend(#DestinationVariable String monitorId) {
if (logger.isDebugEnabled()) {
logger.debug(">>>Handling suspend request for monitor with id " + monitorId);
}
try {
monitoringFacade.disableUrlMonitoring(monitorId);
monitorUpdated(monitorId);// force client update
} catch (Exception e) {
logger.log(Level.ERROR, "Exception: ", e);
}
}
#MessageMapping("/monitor/{monitorId}/resume")
public void handleResume(#DestinationVariable String monitorId) {
if (logger.isDebugEnabled()) {
logger.debug(">>>Handling resume request for monitor with id " + monitorId);
}
try {
monitoringFacade.enableUrlMonitoring(monitorId);
monitorUpdated(monitorId);// force client update
} catch (Exception e) {
logger.log(Level.ERROR, "Exception: ", e);
}
}