org.apache.hadoop.hbase.util

Class ReflectedFunctionCache<I,R>

java.lang.Object

org.apache.hadoop.hbase.util.ReflectedFunctionCache<I,R>

Type Parameters:

I - the input argument type for the resolved functions

R - the return type for the resolved functions

@InterfaceAudience.Private
public final class ReflectedFunctionCache<I,R>
extends Object

Cache to hold resolved Functions of a specific signature, generated through reflection. These can be (relatively) costly to create, but then are much faster than typical Method.invoke calls when executing. The cache is built-up on demand as calls are made to new classes. The functions are cached for the lifetime of the process. If a function cannot be created (security reasons, method not found, etc), a fallback function is cached which always returns null. Callers to getAndCallByName(String, Object) should have handling for null return values.

An instance is created for a specified baseClass (i.e. Filter), argClass (i.e. byte[]), and static methodName to call. These are used to resolve a Function which delegates to that static method, if it is found.

Constructor Summary

Constructors

Constructor and Description
ReflectedFunctionCache(Class<R> baseClass, Class<I> argClass, String staticMethodName)

Method Summary

Modifier and Type	Method and Description
R	getAndCallByName(String className, I argument) Get and execute the Function for the given className, passing the argument to the function and returning the result.

Methods inherited from class java.lang.Object

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

Constructor Detail

ReflectedFunctionCache

public ReflectedFunctionCache(Class<R> baseClass,
                              Class<I> argClass,
                              String staticMethodName)

Method Detail

getAndCallByName

@Nullable
public R getAndCallByName(String className,
                                    I argument)

Get and execute the Function for the given className, passing the argument to the function and returning the result.

Parameters:

className - the full name of the class to lookup

argument - the argument to pass to the function, if found.

Returns:

null if a function is not found for classname, otherwise the result of the function.