package com.atlassian.cache.ehcache;
   
   import java.util.SortedMap;
   
   import com.atlassian.cache.CacheStatisticsKey;
   import com.atlassian.util.concurrent.Supplier;
   
   import com.google.common.collect.ImmutableSortedMap;
   
  import net.sf.ehcache.statistics.StatisticsGateway;
  
  import static com.atlassian.cache.CacheStatisticsKey.EVICTION_COUNT;
  import static com.atlassian.cache.CacheStatisticsKey.HEAP_SIZE;
  import static com.atlassian.cache.CacheStatisticsKey.HIT_COUNT;
  import static com.atlassian.cache.CacheStatisticsKey.MISS_COUNT;
  import static com.atlassian.cache.CacheStatisticsKey.PUT_COUNT;
  import static com.atlassian.cache.CacheStatisticsKey.REMOVE_COUNT;
  import static com.atlassian.cache.CacheStatisticsKey.SIZE;
  import static com.atlassian.util.concurrent.Suppliers.memoize;
  
  /**
   * @since v2.4.0
   */
  public class DelegatingCacheStatistics
  {
      public static SortedMap<CacheStatisticsKey, Supplier<Long>> toStatistics(final StatisticsGateway stats)
      {
          // Note: While most of these statistics we can reasonably expect to be cheap and just memoize, the
          // heap size in bytes is very likely to be expensive.  To make it possible to opt out of retrieving
          // it, we hide it behind a Supplier, here.
          final Supplier<Long> heapSize = new Supplier<Long>()
          {
              @Override
              public Long get()
              {
                  return stats.getLocalHeapSizeInBytes();
              }
          };
  
          return ImmutableSortedMap.<CacheStatisticsKey,Supplier<Long>>orderedBy(CacheStatisticsKey.SORT_BY_LABEL)
                  .put(SIZE, memoize(stats.getSize()))
                  .put(HEAP_SIZE, heapSize)
                  .put(HIT_COUNT, memoize(stats.cacheHitCount()))
                  .put(PUT_COUNT, memoize(stats.cachePutCount()))
                  .put(REMOVE_COUNT, memoize(stats.cacheRemoveCount()))
                  .put(MISS_COUNT, memoize(stats.cacheMissCount()))
                  .put(EVICTION_COUNT, memoize(stats.cacheEvictedCount()))
                  .build();
      }
  }