com.hpe.caf.worker.core.ResponseStreamCache.java Source code

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Here is the source code for com.hpe.caf.worker.core.ResponseStreamCache.java

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/*
 * (c) Copyright 2015-2016 Hewlett Packard Enterprise Development LP
 *
 * 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.hpe.caf.worker.core;

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

import java.io.ByteArrayOutputStream;
import java.net.URI;
import java.util.concurrent.TimeUnit;

/**
 * Provides in-memory caching of web responses on per-URI basis.
 */
public class ResponseStreamCache {
    private static final long CACHE_MAX_SIZE = 1000;
    private static final long CACHE_ITEM_LIFETIME_SECS = 3600; //Store each cached response for up to 1 hour.

    // Underlying in-memory cache.
    private final Cache<URI, ResponseStreamCacheEntry> cacheImpl;

    public ResponseStreamCache() {
        this.cacheImpl = CacheBuilder.newBuilder().maximumSize(CACHE_MAX_SIZE)
                .expireAfterWrite(CACHE_ITEM_LIFETIME_SECS, TimeUnit.SECONDS).build();
    }

    public void put(final URI uri, ByteArrayOutputStream baos, long lifetimeMillis) {
        cacheImpl.put(uri, new ResponseStreamCacheEntry(System.currentTimeMillis() + lifetimeMillis, baos));
    }

    public ByteArrayOutputStream get(final URI uri) {
        checkExpiry(uri);
        ResponseStreamCacheEntry cacheEntry = cacheImpl.getIfPresent(uri);
        return cacheEntry == null ? null : cacheEntry.getResponseStream();
    }

    public void remove(final URI uri) {
        cacheImpl.invalidate(uri);
    }

    private void checkExpiry(final URI uri) {
        ResponseStreamCacheEntry cacheEntry = cacheImpl.getIfPresent(uri);
        if (cacheEntry != null && System.currentTimeMillis() >= cacheEntry.getExpiryTimeMillis()) {
            cacheImpl.invalidate(uri);
        }
    }

    private static class ResponseStreamCacheEntry {
        private long expiryTimeMillis;
        private ByteArrayOutputStream responseStream;

        public ResponseStreamCacheEntry(long expiryTimeMillis, ByteArrayOutputStream baos) {
            this.expiryTimeMillis = expiryTimeMillis;
            this.responseStream = baos;
        }

        public long getExpiryTimeMillis() {
            return expiryTimeMillis;
        }

        public ByteArrayOutputStream getResponseStream() {
            return responseStream;
        }
    }
}