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## org.exist.storage.cache
Interface Cacheable

All Known Implementing Classes:
  Collection

public interface Cacheable

Implemented by all objects that should be stored into a cache. Each object should provide a unique key, an internal reference counter, and a timestamp marker (used to measure how long the object has stayed in the cache). It depends on the concrete cache implementation if and how these fields are used.

Author:
  Wolfgang

Field Summary
`static int` | `MAX_REF`

Method Summary
`boolean` | `allowUnload()` Is it safe to unload the Cacheable from the cache? Called before an object is actually removed.
`int` | `decReferenceCount()` Decrease the reference count of this object by one and return it.
`long` | `getKey()` Get a unique key for the object.
`int` | `getReferenceCount()` Get the current reference count.
`int` | `getTimestamp()` Get the current timestamp marker.
`int` | `incReferenceCount()` Increase the reference count of this object by one and return it.
`boolean` | `isDirty()`
`void` | `setReferenceCount(int count)` Set the reference count of this object.
`void` | `setTimestamp(int timestamp)` Set the timestamp marker.
`boolean` | `sync(boolean syncJournal)` Called before the object is released by the cache.

Field Detail

### MAX_REF

    public static final int MAX_REF

See Also:
  Constant Field Values

Method Detail

### getKey

    public long getKey()

  Get a unique key for the object. Usually this is the page number.

  Returns:
    unique key

### getReferenceCount

    public int getReferenceCount()

  Get the current reference count.

  Returns:
    The count value.

### incReferenceCount

    public int incReferenceCount()

  Increase the reference count of this object by one and return it.

  Returns:
    the reference count

### decReferenceCount

    public int decReferenceCount()

  Decrease the reference count of this object by one and return it.

  Returns:
    the reference count

### setReferenceCount

    public void setReferenceCount(int count)

  Set the reference count of this object.

  Parameters:
    `count` -

### setTimestamp

    public void setTimestamp(int timestamp)

  Set the timestamp marker.

  Parameters:
    `timestamp` -

### getTimestamp

    public int getTimestamp()

  Get the current timestamp marker.

  Returns:
    timestamp marker

### sync

    public boolean sync(boolean syncJournal)

  Called before the object is released by the cache. The object should prepare to be garbage collected. All unwritten data should be flushed to disk.

### allowUnload

    public boolean allowUnload()

  Is it safe to unload the Cacheable from the cache? Called before an object is actually removed. Return false to avoid being removed.

  Returns:
    A boolean where true indicates it can be unloaded.

### isDirty

    public boolean isDirty()

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Copyright (C) Wolfgang Meier. All rights reserved.