org.apache.hadoop.fs.azurebfs.extensions

Class ExtensionHelper

java.lang.Object

org.apache.hadoop.fs.azurebfs.extensions.ExtensionHelper

@InterfaceAudience.LimitedPrivate(value="authorization-subsystems")
 @InterfaceStability.Unstable
public final class ExtensionHelper
extends Object

Classes to help with use of extensions, expecially those implementing @BoundDTExtension.

Method Summary

Modifier and Type	Method and Description
static void	bind(Object extension, URI uri, org.apache.hadoop.conf.Configuration conf) If the passed in extension class implements BoundDTExtension then it will have its BoundDTExtension.bind(URI, Configuration) method called.
static void	close(Object extension) Close an extension if it is closeable.
static String	getCanonicalServiceName(Object extension, String def) Invoke BoundDTExtension.getCanonicalServiceName() or return the default value.
static String	getUserAgentSuffix(Object extension, String def) Invoke BoundDTExtension.getUserAgentSuffix() or return the default value.
static <V> Optional<V>	ifBoundDTExtension(Object extension, Function<? super BoundDTExtension,? extends V> fn) Invoke an operation on an object if it implements the BoundDTExtension interface; returns an optional value.

Methods inherited from class java.lang.Object

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

Method Detail

bind

public static void bind(Object extension,
                        URI uri,
                        org.apache.hadoop.conf.Configuration conf)
                 throws IOException

If the passed in extension class implements BoundDTExtension then it will have its BoundDTExtension.bind(URI, Configuration) method called.

Parameters:

extension - extension to examine and maybe invoke

uri - URI of the filesystem.

conf - configuration of this extension.

Throws:

IOException - failure during binding.

close

public static void close(Object extension)

Close an extension if it is closeable. Any error raised is caught and logged.

Parameters:

extension - extension instance.

getUserAgentSuffix

public static String getUserAgentSuffix(Object extension,
                                        String def)

Invoke BoundDTExtension.getUserAgentSuffix() or return the default value.

Parameters:

extension - extension to invoke

def - default if the class is of the wrong type.

Returns:

a user agent suffix

getCanonicalServiceName

public static String getCanonicalServiceName(Object extension,
                                             String def)

Invoke BoundDTExtension.getCanonicalServiceName() or return the default value.

Parameters:

extension - extension to invoke

def - default if the class is of the wrong type.

Returns:

a canonical service name.

ifBoundDTExtension

public static <V> Optional<V> ifBoundDTExtension(Object extension,
                                                 Function<? super BoundDTExtension,? extends V> fn)

Invoke an operation on an object if it implements the BoundDTExtension interface; returns an optional value.

Type Parameters:

V - return type of te function.

Parameters:

extension - the extension to invoke.

fn - function to apply

Returns:

an optional value which, if not empty, contains the return value of the invoked function. If empty: the object was not of a compatible type.