com.google.api.auth.CachingJwksSupplier.java Source code

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Here is the source code for com.google.api.auth.CachingJwksSupplier.java

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/*
 * Copyright 2016 Google Inc. All Rights Reserved.
 *
 * 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 com.google.api.auth;

import com.google.api.client.util.Preconditions;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Ticker;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;

import org.jose4j.jwk.JsonWebKeySet;

import java.util.concurrent.TimeUnit;

/**
 * A {@link JwksSupplier} that caches results and delegates actual JWKS
 * retrieval to another {@link JwksSupplier}.
 *
 * @author yangguan@google.com
 *
 */
public class CachingJwksSupplier implements JwksSupplier {
    private static final int CACHE_EXPIRATION_IN_MINUTES = 5;

    private final LoadingCache<String, JsonWebKeySet> jwksCache;

    public CachingJwksSupplier(JwksSupplier jwksSupplier) {
        this(Preconditions.checkNotNull(jwksSupplier), Ticker.systemTicker());
    }

    @VisibleForTesting
    CachingJwksSupplier(JwksSupplier jwksSupplier, Ticker ticker) {
        this.jwksCache = CacheBuilder.newBuilder().expireAfterWrite(CACHE_EXPIRATION_IN_MINUTES, TimeUnit.MINUTES)
                .ticker(ticker).build(new JwksCacheLoader(jwksSupplier));
    }

    @Override
    public JsonWebKeySet supply(String issuer) {
        Preconditions.checkNotNull(issuer);

        // Use getUncheck(token) instead of get(token) since we know the loading
        // method (DefaultCacheLoader#load) does not throw checked exception.
        return this.jwksCache.getUnchecked(issuer);
    }

    private static final class JwksCacheLoader extends CacheLoader<String, JsonWebKeySet> {
        private final JwksSupplier jwksSupplier;

        JwksCacheLoader(JwksSupplier jwksSupplier) {
            this.jwksSupplier = jwksSupplier;
        }

        @Override
        public JsonWebKeySet load(String issuer) throws Exception {
            return this.jwksSupplier.supply(issuer);
        }
    }
}