com.alexkasko.unsafe.offheaplong

Class OffHeapLongArrayList

java.lang.Object

com.alexkasko.unsafe.offheaplong.OffHeapLongArrayList

All Implemented Interfaces:

OffHeapAddressable, OffHeapDisposable, OffHeapDisposableIterable<Long>, OffHeapLongAddressable, Iterable<Long>

public class OffHeapLongArrayList
extends Object
implements OffHeapLongAddressable, OffHeapDisposable, Iterable<Long>

Implementation of array-list of long using OffHeapMemory. Memory area will be allocated another time and copied on elements adding. This class doesn't support elements removing. get(long) and set(long, long) access operations indexes are checked using assert keyword (indexes between size and capacity will be rejected).

Default implementation uses sun.misc.Unsafe, with all operations guarded with assert keyword. With assertions enabled in runtime (-ea java switch) AssertionError will be thrown on illegal index access. Without assertions illegal index will crash JVM.

Allocated memory may be freed manually using free() (thread-safe and may be called multiple times) or it will be freed after OffHeapLongArray will be garbage collected.

Note: while class implements Iterable, iterator will create new autoboxed Long object on every next() call, this behaviour is inevitable with iterators in java 6/7.

Author:

alexkasko Date: 3/1/13

Field Summary

Fields

Modifier and Type	Field and Description
private long	capacity
private static int	ELEMENT_LENGTH
private static int	MIN_CAPACITY_INCREMENT
private OffHeapMemory	ohm
private long	size

Constructor Summary

Constructors

Constructor and Description
OffHeapLongArrayList() Constructor, 12 is used as initial capacity
OffHeapLongArrayList(long capacity) Constructor

Method Summary

Methods

Modifier and Type	Method and Description
void	add(long value) Adds element to the end of this list.
long	capacity() Returns number of elements list may contain without additional memory allocation
void	free() Frees allocated memory, may be called multiple times from any thread
long	get(long index) Gets the element at position index from 0 to size-1
boolean	isUnsafe() Whether unsafe implementation of OffHeapMemory is used
OffHeapDisposableIterator<Long>	iterator()
void	reset() Resets the collection setting size to 0.
void	set(long index, long value) Sets the element at position index (from 0 to size-1) to the given value
long	size() Returns number of elements in list
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

MIN_CAPACITY_INCREMENT

private static final int MIN_CAPACITY_INCREMENT

See Also:

Constant Field Values

ELEMENT_LENGTH

private static final int ELEMENT_LENGTH

See Also:

Constant Field Values

ohm

private OffHeapMemory ohm

size

private long size

capacity

private long capacity

Constructor Detail

OffHeapLongArrayList

public OffHeapLongArrayList()

Constructor, 12 is used as initial capacity

OffHeapLongArrayList

public OffHeapLongArrayList(long capacity)

Constructor

Parameters:

capacity - initial capacity

Method Detail

add

public void add(long value)

Adds element to the end of this list. Memory area will be allocated another time and copied on capacity exceed.

Parameters:

value - value to add

isUnsafe

public boolean isUnsafe()

Whether unsafe implementation of OffHeapMemory is used

Returns:

whether unsafe implementation of OffHeapMemory is used

get

public long get(long index)

Gets the element at position index from 0 to size-1

Specified by:

get in interface OffHeapAddressable

Parameters:

index - list index

Returns:

long value

set

public void set(long index,
       long value)

Sets the element at position index (from 0 to size-1) to the given value

Specified by:

set in interface OffHeapLongAddressable

Parameters:

index - list index

value - long value

size

public long size()

Returns number of elements in list

Specified by:

size in interface OffHeapAddressable

Returns:

number of elements in list

capacity

public long capacity()

Returns number of elements list may contain without additional memory allocation

Returns:

number of elements list may contain without additional memory allocation

free

public void free()

Frees allocated memory, may be called multiple times from any thread

Specified by:

free in interface OffHeapDisposable

iterator

public OffHeapDisposableIterator<Long> iterator()

Specified by:

iterator in interface OffHeapDisposableIterable<Long>

Specified by:

iterator in interface Iterable<Long>

reset

public void reset()

Resets the collection setting size to 0. Actual memory contents stays untouched.

toString

public String toString()

Overrides:

toString in class Object