TestLruCache.java

/* 
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 * 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
 * under the License.
 */
package parquet.hadoop;

import org.junit.Test;

import static org.junit.Assert.*;

public class TestLruCache {
    private static final String DEFAULT_KEY = "test";

    private static final class SimpleValue implements LruCache.Value<String, SimpleValue> {
        private boolean current;
        private boolean newerThan;

        public SimpleValue(boolean current, boolean newerThan) {
            this.current = current;
            this.newerThan = newerThan;
        }


        public boolean isCurrent(String key) {
            return current;
        }

        public void setCurrent(boolean current) {
            this.current = current;
        }


        public boolean isNewerThan(SimpleValue otherValue) {
            return newerThan;
        }

    }

    @Test
    public void testMaxSize() {
        LruCache<String, SimpleValue> cache = new LruCache<String, SimpleValue>(1);

        String oldKey = DEFAULT_KEY;
        String newKey = oldKey + "_new";

        SimpleValue oldValue = new SimpleValue(true, true);
        cache.put(oldKey, oldValue);
        assertEquals(oldValue, cache.getCurrentValue(oldKey));
        assertEquals(1, cache.size());

        SimpleValue newValue = new SimpleValue(true, true);
        cache.put(newKey, newValue);
        assertNull(cache.getCurrentValue(oldKey));
        assertEquals(newValue, cache.getCurrentValue(newKey));
        assertEquals(1, cache.size());
    }

    @Test
    public void testOlderValueIsIgnored() {
        LruCache<String, SimpleValue> cache = new LruCache<String, SimpleValue>(1);

        SimpleValue currentValue = new SimpleValue(true, true);
        SimpleValue notAsCurrentValue = new SimpleValue(true, false);
        cache.put(DEFAULT_KEY, currentValue);
        cache.put(DEFAULT_KEY, notAsCurrentValue);
        assertEquals(
                "The existing value in the cache was overwritten",
                currentValue,
                cache.getCurrentValue(DEFAULT_KEY)
        );
    }

    @Test
    public void testOutdatedValueIsIgnored() {
        LruCache<String, SimpleValue> cache = new LruCache<String, SimpleValue>(1);

        SimpleValue outdatedValue = new SimpleValue(false, true);
        cache.put(DEFAULT_KEY, outdatedValue);
        assertEquals(0, cache.size());
        assertNull(cache.getCurrentValue(DEFAULT_KEY));
    }

    @Test
    public void testCurrentValueOverwritesExisting() {
        LruCache<String, SimpleValue> cache = new LruCache<String, SimpleValue>(1);

        SimpleValue currentValue = new SimpleValue(true, true);
        SimpleValue notAsCurrentValue = new SimpleValue(true, false);
        cache.put(DEFAULT_KEY, notAsCurrentValue);
        assertEquals(1, cache.size());
        cache.put(DEFAULT_KEY, currentValue);
        assertEquals(1, cache.size());
        assertEquals(
                "The existing value in the cache was NOT overwritten",
                currentValue,
                cache.getCurrentValue(DEFAULT_KEY)
        );
    }

    @Test
    public void testGetOutdatedValueReturnsNull() {
        LruCache<String, SimpleValue> cache = new LruCache<String, SimpleValue>(1);

        SimpleValue value = new SimpleValue(true, true);
        cache.put(DEFAULT_KEY, value);
        assertEquals(1, cache.size());
        assertEquals(value, cache.getCurrentValue(DEFAULT_KEY));

        value.setCurrent(false);
        assertNull("The value should not be current anymore", cache.getCurrentValue(DEFAULT_KEY));
        assertEquals(0, cache.size());
    }

    @Test
    public void testRemove() {
        LruCache<String, SimpleValue> cache = new LruCache<String, SimpleValue>(1);

        SimpleValue value = new SimpleValue(true, true);
        cache.put(DEFAULT_KEY, value);
        assertEquals(1, cache.size());
        assertEquals(value, cache.getCurrentValue(DEFAULT_KEY));

        // remove the only value
        assertEquals(value, cache.remove(DEFAULT_KEY));
        assertNull(cache.getCurrentValue(DEFAULT_KEY));
        assertEquals(0, cache.size());
    }

    @Test
    public void testClear() {
        LruCache<String, SimpleValue> cache = new LruCache<String, SimpleValue>(2);

        String key1 = DEFAULT_KEY + 1;
        String key2 = DEFAULT_KEY + 2;
        SimpleValue value = new SimpleValue(true, true);
        cache.put(key1, value);
        cache.put(key2, value);
        assertEquals(value, cache.getCurrentValue(key1));
        assertEquals(value, cache.getCurrentValue(key2));
        assertEquals(2, cache.size());

        cache.clear();
        assertNull(cache.getCurrentValue(key1));
        assertNull(cache.getCurrentValue(key2));
        assertEquals(0, cache.size());
    }

}