org.sprinkle.CacheTool.java Source code

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Here is the source code for org.sprinkle.CacheTool.java

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/*
 * * Copyright 2016 Intuit Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.sprinkle;

import java.util.concurrent.CompletableFuture;
import java.util.function.Function;

import com.google.common.cache.Cache;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

/**
 * Created by mboussarov on 6/25/15.
 */
public class CacheTool {
    // Construct a cache for a particular future
    public static <K, V> Cache<K, CompletableFuture<Try<V>>> constructCache(
            CacheBuilder<K, CompletableFuture<Try<V>>> cacheBuilder,
            Function<K, CompletableFuture<Try<V>>> future) {
        return cacheBuilder.build(new CacheLoader<K, CompletableFuture<Try<V>>>() {
            public CompletableFuture<Try<V>> load(K key) { // no checked exception
                return future.apply(key);
            }
        });
    }

    // Construct a get function for this cache
    public static <K, V> Function<K, CompletableFuture<Try<V>>> withCache(
            Cache<K, CompletableFuture<Try<V>>> cache) {
        return a -> {
            try {
                return ((LoadingCache<K, CompletableFuture<Try<V>>>) cache).get(a);
            } catch (Exception ex) {
                CompletableFuture<Try<V>> errorFuture = new CompletableFuture<Try<V>>();
                errorFuture.complete(Try.failure(ex));
                return errorFuture;
            }
        };
    }

    // Construct a get function for this cache that get a value after extracting the key from the input
    public static <K, V, KK> Function<KK, CompletableFuture<Try<V>>> withCache(
            Cache<K, CompletableFuture<Try<V>>> cache, Function<KK, Try<K>> getKeyFunc) {
        Function<Throwable, CompletableFuture<Try<V>>> errorFunc = a -> {
            CompletableFuture<Try<V>> errorFuture = new CompletableFuture<>();
            errorFuture.complete(Try.failure(a));
            return errorFuture;
        };

        return a -> {
            try {
                Try<K> tryKey = getKeyFunc.apply(a);
                if (tryKey.isSuccess()) {
                    return ((LoadingCache<K, CompletableFuture<Try<V>>>) cache).get(tryKey.get());
                } else {
                    CompletableFuture<Try<V>> errorFuture = new CompletableFuture<Try<V>>();
                    errorFuture.complete(Try.failure(tryKey.getException()));
                    return errorFunc.apply(tryKey.getException());
                }
            } catch (Throwable ex) {
                return errorFunc.apply(ex);
            }
        };
    }

    // Construct a function wrapper with cache, the benefit/drawback is that the cache is hidden
    public static <K, V> Function<K, CompletableFuture<Try<V>>> withCache(
            CacheBuilder<K, CompletableFuture<Try<V>>> cacheBuilder,
            Function<K, CompletableFuture<Try<V>>> future) {
        final Cache<K, CompletableFuture<Try<V>>> cache = cacheBuilder
                .build(new CacheLoader<K, CompletableFuture<Try<V>>>() {
                    public CompletableFuture<Try<V>> load(K key) { // no checked exception
                        return future.apply(key);
                    }
                });

        // Close around the cache
        return withCache(cache);
    }

    // Construct a function wrapper with cache, the benefit/drawback is that the cache is hidden
    // Gets a function that extracts the key from the input
    public static <K, V, KK> Function<KK, CompletableFuture<Try<V>>> withCache(
            CacheBuilder<K, CompletableFuture<Try<V>>> cacheBuilder, Function<K, CompletableFuture<Try<V>>> future,
            Function<KK, Try<K>> getKeyFunc) {
        final Cache<K, CompletableFuture<Try<V>>> cache = cacheBuilder
                .build(new CacheLoader<K, CompletableFuture<Try<V>>>() {
                    public CompletableFuture<Try<V>> load(K key) { // no checked exception
                        return future.apply(key);
                    }
                });

        // Close around the cache
        return withCache(cache, getKeyFunc);
    }
}