MmappedRegionsCache (apache-cassandra API)

java.lang.Object
- org.apache.cassandra.io.util.MmappedRegionsCache

All Implemented Interfaces:

java.lang.AutoCloseable
```
@NotThreadSafe
public class MmappedRegionsCache
extends java.lang.Object
implements java.lang.AutoCloseable
```
It is a utility class for caching MmappedRegions primarily used by a FileHandle.Builder when a handle to the same file is created multiple times (as when an sstable is opened early).

Constructor Summary

Constructors
Constructor Description

MmappedRegionsCache()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`close()`
`MmappedRegions`	`getOrCreate(ChannelProxy channel, long length)`	Looks for mmapped regions in cache.
`MmappedRegions`	`getOrCreate(ChannelProxy channel, CompressionMetadata metadata)`	Looks for mmapped regions in cache.

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

- Constructor Detail
  - MmappedRegionsCache
```
public MmappedRegionsCache()
```
- Method Detail
  - getOrCreate
```
public MmappedRegions getOrCreate(ChannelProxy channel,
                                  long length)
```
    Looks for mmapped regions in cache. If found, a shared copy is created and extended to the provided length. If mmapped regions do not exist yet for the provided key, they are created and a shared copy is returned.
    
    Parameters:
    
    channel - channel for which the mmapped regions are requested
    
    length - length of the file
    
    Returns:
    
    a shared copy of the cached mmapped regions
  - getOrCreate
```
public MmappedRegions getOrCreate(ChannelProxy channel,
                                  CompressionMetadata metadata)
```
    Looks for mmapped regions in cache. If found, a shared copy is created and extended according to the provided metadata. If mmapped regions do not exist yet for the provided key, they are created and a shared copy is returned.
    
    Parameters:
    
    channel - channel for which the mmapped regions are requested
    
    metadata - compression metadata of the file
    
    Returns:
    
    a shared copy of the cached mmapped regions
  - close
```
public void close()
```
    Specified by:
    
    close in interface java.lang.AutoCloseable