VolumeChooser (Apache Accumulo Core 2.1.0 API)

All Known Implementing Classes:

DelegatingChooser, PreferredVolumeChooser, RandomVolumeChooser, SpaceAwareVolumeChooser
```
public interface VolumeChooser
```
Helper used to select from a set of Volume URIs. N.B. implementations must be threadsafe. VolumeChooser.equals will be used for internal caching.
Implementations may wish to store configuration in Accumulo's system configuration using the Property.GENERAL_ARBITRARY_PROP_PREFIX. They may also benefit from using per-table configuration using Property.TABLE_ARBITRARY_PROP_PREFIX.

Since:

2.1.0

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Set<String>`	`choosable(VolumeChooserEnvironment env, Set<String> options)`	Return the subset of volumes that could possibly be chosen by this chooser across all invocations of `choose(VolumeChooserEnvironment, Set)`.
`String`	`choose(VolumeChooserEnvironment env, Set<String> options)`	Choose a volume from the provided options.

- Method Detail
  - choose
```
String choose(VolumeChooserEnvironment env,
              Set<String> options)
```
    Choose a volume from the provided options.
    
    Parameters:
    
    env - the server environment provided by the calling framework
    
    options - the list of volumes to choose from
    
    Returns:
    
    one of the options
  - choosable
```
Set<String> choosable(VolumeChooserEnvironment env,
                      Set<String> options)
```
    Return the subset of volumes that could possibly be chosen by this chooser across all invocations of choose(VolumeChooserEnvironment, Set). Currently this is used to determine if all of the volumes that could be chosen for write ahead logs support the needed filesystem operations. There may be other use cases in the future.
    
    Parameters:
    
    env - the server environment provided by the calling framework
    
    options - the subset of volumes to choose from
    
    Returns:
    
    array of valid options