| /* |
| * 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 under the License. |
| */ |
| |
| package org.apache.cassandra.io.sstable.keycache; |
| |
| import java.util.concurrent.atomic.LongAdder; |
| import javax.annotation.Nonnull; |
| import javax.annotation.Nullable; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import org.apache.cassandra.cache.InstrumentingCache; |
| import org.apache.cassandra.cache.KeyCacheKey; |
| import org.apache.cassandra.io.sstable.AbstractRowIndexEntry; |
| |
| /** |
| * A simple wrapper of possibly global cache with local metrics. |
| */ |
| public class KeyCache |
| { |
| public static final KeyCache NO_CACHE = new KeyCache(null); |
| |
| private final static Logger logger = LoggerFactory.getLogger(KeyCache.class); |
| |
| private final InstrumentingCache<KeyCacheKey, AbstractRowIndexEntry> cache; |
| private final LongAdder hits = new LongAdder(); |
| private final LongAdder requests = new LongAdder(); |
| |
| public KeyCache(@Nullable InstrumentingCache<KeyCacheKey, AbstractRowIndexEntry> cache) |
| { |
| this.cache = cache; |
| } |
| |
| public long getHits() |
| { |
| return cache != null ? hits.sum() : 0; |
| } |
| |
| public long getRequests() |
| { |
| return cache != null ? requests.sum() : 0; |
| } |
| |
| public void put(@Nonnull KeyCacheKey cacheKey, @Nonnull AbstractRowIndexEntry info) |
| { |
| if (cache == null) |
| return; |
| |
| logger.trace("Adding cache entry for {} -> {}", cacheKey, info); |
| cache.put(cacheKey, info); |
| } |
| |
| public @Nullable AbstractRowIndexEntry get(KeyCacheKey key, boolean updateStats) |
| { |
| if (cache == null) |
| return null; |
| |
| if (updateStats) |
| { |
| requests.increment(); |
| AbstractRowIndexEntry r = cache.get(key); |
| if (r != null) |
| hits.increment(); |
| return r; |
| } |
| else |
| { |
| return cache.getInternal(key); |
| } |
| } |
| |
| public boolean isEnabled() |
| { |
| return cache != null; |
| } |
| } |