caffeine getAll

CaffeineGetAll.java

package consulting.crafter.cache;

import com.github.benmanes.caffeine.cache.CacheLoader;
import com.github.benmanes.caffeine.cache.Caffeine;
import com.github.benmanes.caffeine.cache.LoadingCache;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;

import static java.util.Arrays.asList;
import static java.util.Collections.emptyList;
import static java.util.Collections.singletonList;

public class Main {

    public static void main(String[] args) {
        LoadingCache<String, String> cache = Caffeine.newBuilder()
                .maximumSize(100)
                .expireAfterWrite(5, TimeUnit.MINUTES)
                .refreshAfterWrite(1, TimeUnit.MINUTES)
                .build(new CacheLoader<String, String>() {
                    @Nullable
                    @Override
                    public String load(@NonNull String key) throws Exception {
                        System.out.println("+> Loading keys " + String.join(",", key));
                        return "Loaded-" + key;
                    }

                    @Override
                    public @NonNull Map<String, String> loadAll(@NonNull Iterable<? extends String> keys) throws Exception {
                        System.out.println("-> Loading keys " + String.join(",", keys));

                        Map<String, String> retval = new HashMap<>();
                        keys.forEach(key -> {
                            retval.put(key, "Loaded-" + key);
                        });

                        return retval;
                    }
                });

        System.out.println("<-" + String.join(",", cache.getAll(singletonList("1")).values()));
        System.out.println("<-" + String.join(",", cache.getAll(asList("1", "2")).values()));
        System.out.println("<-" + String.join(",", cache.getAll(asList("1", "2", "3")).values()));
        System.out.println("<-" + String.join(",", cache.getAll(asList("1", "2", "3", "4")).values()));
        System.out.println("<-" + String.join(",", cache.getAll(asList("4", "1")).values()));
        System.out.println("<-" + cache.get("4"));
        // Only this will use load because we're loading one element and it doesn't exist in cache
        System.out.println("<-" + cache.get("5"));
        System.out.println("<-" + cache.getAll(emptyList()));
    }
}