org.apache.hadoop.hbase.regionserver

Class Chunk

java.lang.Object

org.apache.hadoop.hbase.regionserver.Chunk

Direct Known Subclasses:

OffheapChunk, OnheapChunk

@InterfaceAudience.Private
public abstract class Chunk
extends Object

A chunk of memory out of which allocations are sliced.

Field Summary

Fields

Modifier and Type	Field and Description
protected AtomicInteger	allocCount Total number of allocations satisfied from this buffer
protected ByteBuffer	data Actual underlying data
protected AtomicInteger	nextFreeOffset Offset for the next allocation, or the sentinel value -1 which implies that the chunk is still uninitialized.
protected static int	OOM
protected int	size Size of chunk in bytes
protected static int	UNINITIALIZED

Constructor Summary

Constructors

Constructor and Description
Chunk(int size, int id) Create an uninitialized chunk.
Chunk(int size, int id, boolean fromPool) Create an uninitialized chunk.

Method Summary

Modifier and Type	Method and Description
int	alloc(int size) Try to allocate size bytes from the chunk.
void	init() Actually claim the memory for this chunk.
String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

data

protected ByteBuffer data

Actual underlying data

UNINITIALIZED

protected static final int UNINITIALIZED

See Also:

Constant Field Values

OOM

protected static final int OOM

See Also:

Constant Field Values

nextFreeOffset

protected AtomicInteger nextFreeOffset

Offset for the next allocation, or the sentinel value -1 which implies that the chunk is still uninitialized.

allocCount

protected AtomicInteger allocCount

Total number of allocations satisfied from this buffer

size

protected final int size

Size of chunk in bytes

Constructor Detail

Chunk

public Chunk(int size,
             int id)

Create an uninitialized chunk. Note that memory is not allocated yet, so this is cheap.

Parameters:

size - in bytes

id - the chunk id

Chunk

public Chunk(int size,
             int id,
             boolean fromPool)

Create an uninitialized chunk. Note that memory is not allocated yet, so this is cheap.

Parameters:

size - in bytes

id - the chunk id

fromPool - if the chunk is formed by pool

Method Detail

init

public void init()

Actually claim the memory for this chunk. This should only be called from the thread that constructed the chunk. It is thread-safe against other threads calling alloc(), who will block until the allocation is complete.

alloc

public int alloc(int size)

Try to allocate size bytes from the chunk. If a chunk is tried to get allocated before init() call, the thread doing the allocation will be in busy-wait state as it will keep looping till the nextFreeOffset is set.

Returns:

the offset of the successful allocation, or -1 to indicate not-enough-space

toString

public String toString()

Overrides:

toString in class Object