背景：系统使用了Spring-Redis-Data来进行做数据的缓存。
CacheEvict
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Inherited
@Documented
public @interface CacheEvict {
……
boolean allEntries() default false;
……
}
在项目中使用了@CacheEvict(allEntries=true)属性的时候，系统出现了Redis的CPU飚高。并且还出现了keys xxx::*的命令。接下来就一探究竟，看看到底发生了什么。
SpringCacheAnnotationParser
private CacheEvictOperation parseEvictAnnotation(
AnnotatedElement ae, DefaultCacheConfig defaultConfig, CacheEvict cacheEvict) {
CacheEvictOperation.Builder builder = new CacheEvictOperation.Builder();
builder.setName(ae.toString());
builder.setCacheNames(cacheEvict.cacheNames());
builder.setCondition(cacheEvict.condition());
builder.setKey(cacheEvict.key());
builder.setKeyGenerator(cacheEvict.keyGenerator());
builder.setCacheManager(cacheEvict.cacheManager());
builder.setCacheResolver(cacheEvict.cacheResolver());
builder.setCacheWide(cacheEvict.allEntries());
builder.setBeforeInvocation(cacheEvict.beforeInvocation());
defaultConfig.applyDefault(builder);
CacheEvictOperation op = builder.build();
validateCacheOperation(ae, op);
return op;
}
在parseEvictAnnotation方法中找到builder.setCacheWide(cacheEvict.allEntries()),系统将allEntries的属性设置到了builder中，最终调用CacheEvictOperation op = builder.build();方法，将cacheWide设置给CacheEvictOperation。
CacheInterceptor
public class CacheInterceptor extends CacheAspectSupport implements MethodInterceptor, Serializable {
@Override
@Nullable
public Object invoke(final MethodInvocation invocation) throws Throwable {
Method method = invocation.getMethod();
CacheOperationInvoker aopAllianceInvoker = () -> {
try {
return invocation.proceed();
}
catch (Throwable ex) {
throw new CacheOperationInvoker.ThrowableWrapper(ex);
}
};
try {
return execute(aopAllianceInvoker, invocation.getThis(), method, invocation.getArguments());
}
catch (CacheOperationInvoker.ThrowableWrapper th) {
throw th.getOriginal();
}
}
}
最终系统执行return execute(aopAllianceInvoker, invocation.getThis(), method, invocation.getArguments());接下来看下父类中的CacheAspectSupport.execute方法
@Nullable
protected Object execute(CacheOperationInvoker invoker, Object target, Method method, Object[] args) {
// Check whether aspect is enabled (to cope with cases where the AJ is pulled in automatically)
if (this.initialized) {
Class<?> targetClass = getTargetClass(target);
CacheOperationSource cacheOperationSource = getCacheOperationSource();
if (cacheOperationSource != null) {
Collection<CacheOperation> operations = cacheOperationSource.getCacheOperations(method, targetClass);
if (!CollectionUtils.isEmpty(operations)) {
return execute(invoker, method,
new CacheOperationContexts(operations, method, args, target, targetClass));
}
}
}
return invoker.invoke();
}
继续调用execute方法
@Nullable
private Object execute(final CacheOperationInvoker invoker, Method method, CacheOperationContexts contexts) {
// Special handling of synchronized invocation
if (contexts.isSynchronized()) {
CacheOperationContext context = contexts.get(CacheableOperation.class).iterator().next();
if (isConditionPassing(context, CacheOperationExpressionEvaluator.NO_RESULT)) {
Object key = generateKey(context, CacheOperationExpressionEvaluator.NO_RESULT);
Cache cache = context.getCaches().iterator().next();
try {
return wrapCacheValue(method, cache.get(key, () -> unwrapReturnValue(invokeOperation(invoker))));
}
catch (Cache.ValueRetrievalException ex) {
// The invoker wraps any Throwable in a ThrowableWrapper instance so we
// can just make sure that one bubbles up the stack.
throw (CacheOperationInvoker.ThrowableWrapper) ex.getCause();
}
}
else {
// No caching required, only call the underlying method
return invokeOperation(invoker);
}
}
// Process any early evictions
processCacheEvicts(contexts.get(CacheEvictOperation.class), true,
CacheOperationExpressionEvaluator.NO_RESULT);
// Check if we have a cached item matching the conditions
Cache.ValueWrapper cacheHit = findCachedItem(contexts.get(CacheableOperation.class));
// Collect puts from any @Cacheable miss, if no cached item is found
List<CachePutRequest> cachePutRequests = new LinkedList<>();
if (cacheHit == null) {
collectPutRequests(contexts.get(CacheableOperation.class),
CacheOperationExpressionEvaluator.NO_RESULT, cachePutRequests);
}
Object cacheValue;
Object returnValue;
if (cacheHit != null && !hasCachePut(contexts)) {
// If there are no put requests, just use the cache hit
cacheValue = cacheHit.get();
returnValue = wrapCacheValue(method, cacheValue);
}
else {
// Invoke the method if we don't have a cache hit
returnValue = invokeOperation(invoker);
cacheValue = unwrapReturnValue(returnValue);
}
// Collect any explicit @CachePuts
collectPutRequests(contexts.get(CachePutOperation.class), cacheValue, cachePutRequests);
// Process any collected put requests, either from @CachePut or a @Cacheable miss
for (CachePutRequest cachePutRequest : cachePutRequests) {
cachePutRequest.apply(cacheValue);
}
// Process any late evictions
processCacheEvicts(contexts.get(CacheEvictOperation.class), false, cacheValue);
return returnValue;
}
最终调用processCacheEvicts方法
private void processCacheEvicts(
Collection<CacheOperationContext> contexts, boolean beforeInvocation, @Nullable Object result) {
for (CacheOperationContext context : contexts) {
CacheEvictOperation operation = (CacheEvictOperation) context.metadata.operation;
if (beforeInvocation == operation.isBeforeInvocation() && isConditionPassing(context, result)) {
performCacheEvict(context, operation, result);
}
}
}
继续调用performCacheEvict
private void performCacheEvict(
CacheOperationContext context, CacheEvictOperation operation, @Nullable Object result) {
Object key = null;
for (Cache cache : context.getCaches()) {
if (operation.isCacheWide()) {
logInvalidating(context, operation, null);
doClear(cache);
}
else {
if (key == null) {
key = generateKey(context, result);
}
logInvalidating(context, operation, key);
doEvict(cache, key);
}
}
}
最终会发现，当cacheWide为true的情况下会走doClear方法，接下来看下doClear方法。
protected void doClear(Cache cache) {
try {
cache.clear();
}
catch (RuntimeException ex) {
getErrorHandler().handleCacheClearError(ex, cache);
}
}
这里面最终调用了cache.clear()方法,这里使用的redisCache，直接进去redisCache
public void clear() {
byte[] pattern = conversionService.convert(createCacheKey("*"), byte[].class);
cacheWriter.clean(name, pattern);
}
conversionService.convert(createCacheKey("*"), byte[].class);这句话的目的是为了获取前缀信息。比如说fuck::123,那么转换后就变成了fuck::*。接下来看下cacheWriter.clean(name, pattern);方法。
@Override
public void clean(String name, byte[] pattern) {
Assert.notNull(name, "Name must not be null!");
Assert.notNull(pattern, "Pattern must not be null!");
execute(name, connection -> {
boolean wasLocked = false;
try {
if (isLockingCacheWriter()) {
doLock(name, connection);
wasLocked = true;
}
byte[][] keys = Optional.ofNullable(connection.keys(pattern)).orElse(Collections.emptySet())
.toArray(new byte[0][]);
if (keys.length > 0) {
connection.del(keys);
}
} finally {
if (wasLocked && isLockingCacheWriter()) {
doUnlock(name, connection);
}
}
return "OK";
});
}
这段代码就是删除的一系列逻辑，导致cpu飚高的代码也就在这块了。byte[][] keys = Optional.ofNullable(connection.keys(pattern)).orElse(Collections.emptySet()).toArray(new byte[0][]);从这段代码里面在细分一下connection.keys(pattern),这句话也就是罪魁祸首，转换完就变成了keys fuck::*,那这就是相当于查出来以fuck开头的所有key，然后再去调用connection.del(keys);删除，然鹅keys *是要付出代价的，也就是CPU飚高的原因。
