/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you 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
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package org.codehaus.groovy.runtime.memoize

import java.lang.ref.SoftReference
import java.util.concurrent.CyclicBarrier
import java.util.concurrent.TimeUnit

/**
 * @author Vaclav Pech
 */
public class CacheCleanupTest extends GroovyTestCase {
    private static final Object ANCHOR = "I'm never gonna go"
    
    public void testUnlimitedCache() {
        checkCache(new UnlimitedConcurrentCache())
        checkCache(new LRUCache(10))
    }

    private def checkCache(MemoizeCache cache) {
        assert cache.cache.size() == 0
        cache.put('key1', new SoftReference(ANCHOR))
        cache.put('key2', new SoftReference(ANCHOR))
        assert cache.cache.size() == 2
        cache.put('key3', new SoftReference(null))  //Simulating evicted objects
        cache.put('key4', new SoftReference(null))
        cache.cleanUpNullReferences()
        assert cache.cache.size() == 2
    }

    public void testUnlimitedCacheConcurrently() {
        checkCacheConcurrently(new UnlimitedConcurrentCache())
        checkCacheConcurrently(new LRUCache(2000))
        checkCacheConcurrently(new LRUCache(50))  //testing a cache that removes old elements
    }

    private def checkCacheConcurrently(MemoizeCache cache) {
        assert cache.cache.size() == 0
        cache.put('key1', new SoftReference(ANCHOR))
        cache.put('key2', new SoftReference(ANCHOR))
        assert cache.cache.size() == 2
        for (i in (3..1000)) {
            cache.put("key${i}", new SoftReference(null))  //Simulating evicted objects
            cache.get('key1')  //touch the non-null cache entries to keep them hot to prevent a potential LRU algorithm from evicting them
            cache.get('key2')
        }

        final CyclicBarrier barrier = new CyclicBarrier(11)
        10.times {
            Thread.start {
                barrier.await()
                cache.cleanUpNullReferences()
                barrier.await()
            }
        }
        barrier.await(30, TimeUnit.SECONDS)  //start threads
        barrier.await(30, TimeUnit.SECONDS)  //wait for threads to finish

        assert cache.cache.size() == 2
    }
}
