mcarleio / sciurus

import io.mcarle.sciurus.ExecutionIdentifier;

import io.mcarle.sciurus.annotation.Cache;

import org.aspectj.lang.ProceedingJoinPoint;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import java.io.Serializable;

import java.time.Duration;

class CacheAspectHandler {

    private static final Logger LOG = LoggerFactory.getLogger(CacheAspectHandler.class);

    private final static Object EMPTY = CustomCache.EMPTY;

    @SuppressWarnings({"finally", "ReturnInsideFinallyBlock"})

    static Object executeAndCache(ProceedingJoinPoint joinPoint, Cache cache) throws Throwable {

        ExecutionIdentifier executionIdentifier = null;

        Object result = EMPTY;

        try {

            // check for any cached value

            executionIdentifier = new ExecutionIdentifier(joinPoint.getSignature().toLongString(), joinPoint.getArgs());

            result = loadFromCache(executionIdentifier, cache);

        } finally {

            if (result != EMPTY) {

                // if cached value was found, return it

                return result;

            }

            // if no cached value is present, execute method

            result = joinPoint.proceed();

            // if successfull

            try {

                // save the result into cache

                saveIntoCache(executionIdentifier, (Serializable) result, cache);

            } finally {

                // despite any errors while saving to cache, ignore them and return the result

                return result;

            }

        }

    }

    private static Object loadFromCache(ExecutionIdentifier executionIdentifier, Cache cache) {

        CustomCache customCache = getCache(cache, executionIdentifier);

        if (customCache != null) {

            try {

                return customCache.get(executionIdentifier);

            } catch (Throwable t) {

                LOG.warn("Got exception from cache '{}' while reading: {}", cache.cacheName(), executionIdentifier, t);

            }

        }

        return EMPTY;

    }

        }

    }

    private static CustomCache getCache(Cache cache, ExecutionIdentifier executionIdentifier) {

        try {

            return CacheRegister.INSTANCE.getCache(cache.cacheName());

        } catch (CacheException.UnknownCache ce) {

            LOG.warn("No cache with name '{}' registered: {}", cache.cacheName(), executionIdentifier);

        } catch (CacheException.CacheSupplierReturnedNull ce) {

            LOG.warn("Cache returned from supplier for '{}' was null: {}", cache.cacheName(), executionIdentifier);

        } catch (CacheException.CacheSupplierThrewException ce) {

            LOG.warn("Got exception from cache supplier for '{}': {}", cache.cacheName(), executionIdentifier, ce.getCause());

        }

        return null;

    }

}