org.apache.drill.common

Class AutoCloseablePointer<T extends AutoCloseable>

java.lang.Object

org.apache.drill.common.AutoCloseablePointer<T>

Type Parameters:

T - type of the pointer

All Implemented Interfaces:

AutoCloseable

public final class AutoCloseablePointer<T extends AutoCloseable>
extends Object
implements AutoCloseable

A class similar to Pointer<>, but with features unique to holding AutoCloseable pointers. The AutoCloseablePointer<> must be closed when it will no longer be used.

If you're familiar with C++/Boost's shared_ptr<>, you might recognize some of the features here.

Constructor Summary

Constructors

Constructor and Description
AutoCloseablePointer() Constructor for a null-valued pointer.
AutoCloseablePointer(T pointer) Constructor for a pointer value.

Method Summary

Modifier and Type	Method and Description
T	adopt() The caller adopts the pointer; the holder is set to null, and will no longer be responsible for close()ing this pointer.
void	assign(T newP) Assign a new pointer to this holder.
void	assignNoChecked(T newP) Like assign(AutoCloseable), except that any exception thrown by closing the previously held pointer is wrapped with (an unchecked) RuntimeException.
void	close()
T	get() Get the raw pointer out for use.

Methods inherited from class java.lang.Object

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

Constructor Detail

AutoCloseablePointer

public AutoCloseablePointer()

Constructor for a null-valued pointer.

AutoCloseablePointer

public AutoCloseablePointer(T pointer)

Constructor for a pointer value.

Parameters:

pointer - the initial pointer value

Method Detail

close

public void close()
           throws Exception

Specified by:

close in interface AutoCloseable

Throws:

Exception

get

public T get()

Get the raw pointer out for use.

Returns:

the raw pointer

adopt

public T adopt()

The caller adopts the pointer; the holder is set to null, and will no longer be responsible for close()ing this pointer.

Returns:

the pointer being adopted; may be null

assign

public void assign(T newP)
            throws Exception

Assign a new pointer to this holder. Any currently held pointer will first be closed. If closing the currently held pointer throws an exception, the new pointer is still assigned, and the holder must still be closed to close that.

This makes it convenient to assign a new pointer without having to check for a previous value and worry about cleaning it up; this does all that.

Parameters:

newP - the new pointer to hold

Throws:

Exception - any exception thrown by closing the currently held pointer

assignNoChecked

public void assignNoChecked(T newP)

Like assign(AutoCloseable), except that any exception thrown by closing the previously held pointer is wrapped with (an unchecked) RuntimeException.

Parameters:

newP - the new pointer to hold