# Class MapQueryCache

java.lang.Object
org.apache.cayenne.cache.MapQueryCache

All Implemented Interfaces:
  `Serializable, QueryCache`

public class MapQueryCache extends Object implements QueryCache, Serializable
A default implementation of the `QueryCache` interface that stores data in a non-expiring LRUMap.

Since:
  3.0
See Also:
  - Serialized Form

- ## Field Summary

  Fields
  Modifier and Type
  Field
  Description
  `protected final Map<String, Map<String,List<?>>>`
  `cacheGroups`
  `static final int`
  `DEFAULT_CACHE_SIZE`

- ## Constructor Summary

  Constructors
  Constructor
  Description
  `MapQueryCache()`
  `MapQueryCache(int maxSize)`

- ## Method Summary

  Modifier and Type
  Method
  Description
  `protected String`
  `cacheName(QueryMetadata metadata)`
  `void`
  `clear()`
  Deprecated.
  `protected Map<String,List<?>>`
  `createCache(String cacheName)`
  `protected Map<String,List<?>>`
  `createIfAbsent(String cacheName)`
  `protected Map<String,List<?>>`
  `createIfAbsent(QueryMetadata metadata)`
  `List`
  `get(QueryMetadata metadata)`
  Returns a cached query result for the given QueryMetadata or null if the result is not cached or is expired.
  `List`
  `get(QueryMetadata metadata, QueryCacheEntryFactory factory)`
  Returns a non-null cached value.
  `protected Map<String,List<?>>`
  `getCache(String name)`
  `void`
  `put(QueryMetadata metadata, List results)`
  `void`
  `remove(String key)`
  Removes a single entry from cache.
  `void`
  `removeGroup(String groupKey)`
  Removes a group of entries identified by group key.
  `void`
  `removeGroup(String groupKey, Class<?> keyType, Class<?> valueType)`
  Removes a group of entries identified by group key.
  `int`
  `size()`

  ### Methods inherited from class Object

  `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- ## Field Details

  - ### DEFAULT_CACHE_SIZE

    public static final int DEFAULT_CACHE_SIZE
    See Also:
      - Constant Field Values

  - ### cacheGroups

    protected final Map<String, Map<String,List<?>>> cacheGroups

- ## Constructor Details

  - ### MapQueryCache

    public MapQueryCache()

  - ### MapQueryCache

    public MapQueryCache(int maxSize)

- ## Method Details

  - ### get

    public List get(QueryMetadata metadata)
    Description copied from interface: `QueryCache`
    Returns a cached query result for the given QueryMetadata or null if the result is not cached or is expired.
    Specified by:
      `get` in interface `QueryCache`

  - ### get

    public List get(QueryMetadata metadata, QueryCacheEntryFactory factory)
    Returns a non-null cached value. If it is not present in the cache, it is obtained by calling `QueryCacheEntryFactory.createObject()` without blocking the cache. As a result there is a potential of multiple threads to be updating cache in parallel - this wouldn't lead to corruption of the cache, but can be suboptimal.
    Specified by:
      `get` in interface `QueryCache`

  - ### put

    public void put(QueryMetadata metadata, List results)
    Specified by:
      `put` in interface `QueryCache`

  - ### remove

    public void remove(String key)
    Description copied from interface: `QueryCache`
    Removes a single entry from cache.
    Specified by:
      `remove` in interface `QueryCache`

  - ### removeGroup

    public void removeGroup(String groupKey)
    Description copied from interface: `QueryCache`
    Removes a group of entries identified by group key. Note that depending on implementation this method may either actively remove the entries belonging to the group or just mark them as expired, so that they are refreshed on the next access. In the former case the cache size would shrink, but in the later the cache size will not change after calling this method.
    Specified by:
      `removeGroup` in interface `QueryCache`

  - ### removeGroup

    public void removeGroup(String groupKey, Class<?> keyType, Class<?> valueType)
    Description copied from interface: `QueryCache`
    Removes a group of entries identified by group key. Can be used if cache provider supports strictly typed caches.
    Specified by:
      `removeGroup` in interface `QueryCache`
    See Also:
      - `QueryCache.removeGroup(String)`

  - ### clear

    @Deprecated(since="4.0") public void clear()
    Deprecated.
    Description copied from interface: `QueryCache`
    Clears all cache entries.
    Specified by:
      `clear` in interface `QueryCache`

  - ### size

    public int size()

  - ### createIfAbsent

    protected Map<String,List<?>> createIfAbsent(QueryMetadata metadata)

  - ### createIfAbsent

    protected Map<String,List<?>> createIfAbsent(String cacheName)

  - ### createCache

    protected Map<String,List<?>> createCache(String cacheName)

  - ### getCache

    protected Map<String,List<?>> getCache(String name)

  - ### cacheName

    protected String cacheName(QueryMetadata metadata)