MetaCache

java.lang.Object
- org.apache.commons.jexl3.internal.MetaCache

```
final class MetaCache
extends java.lang.Object
```
A meta-cache that tracks multiple JexlCache instances via weak references.
Each JexlCache created by this MetaCache is held via a WeakReference, allowing it to be garbage collected as soon as no strong references exist.

This allows for collective management of multiple caches, in particular clearing all caches at once. This operation is typically called when the uberspect class loader needs to change.

Field Summary

Fields
Modifier and Type	Field	Description
`private java.util.function.IntFunction<JexlCache<?,?>>`	`factory`
`private java.lang.ref.ReferenceQueue<JexlCache<?,?>>`	`queue`
`private java.util.Set<java.lang.ref.Reference<JexlCache<?,?>>>`	`references`

Constructor Summary

Constructors
Constructor Description

MetaCache(java.util.function.IntFunction<JexlCache<?,?>> factory)
Constructs a MetaCache with the given cache factory.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`private int`	`cleanUp()`	Cleans up all references whose referent (the cache) has been garbage collected.
`(package private) void`	`clearCaches()`	Clears all caches tracked by this MetaCache.
`(package private) <K,V> JexlCache<K,V>`	`createCache(int capacity)`
`(package private) int`	`size()`	Gets the number of live caches currently tracked by this MetaCache.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - factory
```
private final java.util.function.IntFunction<JexlCache<?,?>> factory
```
  - references
```
private final java.util.Set<java.lang.ref.Reference<JexlCache<?,?>>> references
```
  - queue
```
private final java.lang.ref.ReferenceQueue<JexlCache<?,?>> queue
```
- Constructor Detail
  - MetaCache
```
MetaCache(java.util.function.IntFunction<JexlCache<?,?>> factory)
```
    Constructs a MetaCache with the given cache factory.
    
    Parameters:
    
    factory - The factory function to create JexlCache instances given a capacity.
- Method Detail
  - createCache
```
<K,V> JexlCache<K,V> createCache(int capacity)
```
  - clearCaches
```
void clearCaches()
```
    Clears all caches tracked by this MetaCache.
  - cleanUp
```
private int cleanUp()
```
    Cleans up all references whose referent (the cache) has been garbage collected.
    This method must be invoked while holding the lock on references.
    
    Returns:
    
    The remaining number of caches.
  - size
```
int size()
```
    Gets the number of live caches currently tracked by this MetaCache.
    Any cache that is no longer strongly reference will get removed from the tracked set.
    
    Returns:
    
    The number of caches.