Class MapCache

server/src/main/java/org/apache/druid/client/cache/MapCache.java:38–189

/**
 */
public class MapCache implements Cache
{
  public static Cache create(long sizeInBytes)
  {
    return new MapCache(new ByteCountingLRUMap(sizeInBytes));
  }

  private final Map<ByteBuffer, byte[]> baseMap;
  private final ByteCountingLRUMap byteCountingLRUMap;

  private final Map<String, byte[]> namespaceId;
  private final AtomicInteger ids;

  private final Object clearLock = new Object();

  private final AtomicLong hitCount = new AtomicLong(0);
  private final AtomicLong missCount = new AtomicLong(0);

  MapCache(
      ByteCountingLRUMap byteCountingLRUMap
  )
  {
    this.byteCountingLRUMap = byteCountingLRUMap;
    this.baseMap = Collections.synchronizedMap(byteCountingLRUMap);

    namespaceId = new HashMap<>();
    ids = new AtomicInteger();
  }

  @Override
  public CacheStats getStats()
  {
    return new CacheStats(
        hitCount.get(),
        missCount.get(),
        byteCountingLRUMap.size(),
        byteCountingLRUMap.getNumBytes(),
        byteCountingLRUMap.getEvictionCount(),
        0,
        0
    );
  }

  @Override
  public byte[] get(NamedKey key)
  {
    final byte[] retVal;
    synchronized (clearLock) {
      retVal = baseMap.get(computeKey(getNamespaceId(key.namespace), key.key));
    }
    if (retVal == null) {
      missCount.incrementAndGet();
    } else {
      hitCount.incrementAndGet();
    }
    return retVal;
  }