com.hazelcast.memory

Interface HazelcastMemoryManager

All Superinterfaces:

com.hazelcast.nio.Disposable, com.hazelcast.internal.memory.MemoryAllocator

All Known Implementing Classes:

PoolingMemoryManager, StandardMemoryManager, ThreadLocalPoolingMemoryManager

public interface HazelcastMemoryManager
extends com.hazelcast.internal.memory.MemoryAllocator

Specialization of MemoryAllocator to CPU's native address space. Also includes methods specific to Hazelcast's pooling memory managers.

Field Summary

Fields

Modifier and Type	Field and Description
static long	SIZE_INVALID Indicates that size of a memory block is not known by this memory manager.

Fields inherited from interface com.hazelcast.internal.memory.MemoryAllocator

NULL_ADDRESS

Method Summary

Modifier and Type	Method and Description
long	allocate(long size) Allocates memory from an internal memory pool or falls back to OS if not enough memory available in pool.
void	compact() Compacts the memory region.
void	free(long address, long size) Gives allocated memory block back to internal pool or to OS if pool is over capacity.
long	getAllocatedSize(long address) Returns allocated size of memory block as if it belongs to and is allocated by this memory manager.
com.hazelcast.memory.MemoryStats	getMemoryStats()
com.hazelcast.internal.memory.MemoryAllocator	getSystemAllocator()
long	getUsableSize(long address) Returns size of memory block as if it belongs to and is allocated by this memory manager.
boolean	isDisposed() Gets the disposed state of this memory manager.
long	newSequence() Creates a new sequence.
long	validateAndGetAllocatedSize(long address) Returns allocated size of memory block if and only if it belongs to and is allocated by this memory manager.
long	validateAndGetUsableSize(long address) Returns size of memory block if and only if it belongs to and is allocated by this memory manager.

Methods inherited from interface com.hazelcast.internal.memory.MemoryAllocator

reallocate

Methods inherited from interface com.hazelcast.nio.Disposable

dispose

Field Detail

SIZE_INVALID

static final long SIZE_INVALID

Indicates that size of a memory block is not known by this memory manager.

See Also:

Constant Field Values

Method Detail

allocate

long allocate(long size)

Allocates memory from an internal memory pool or falls back to OS if not enough memory available in pool. Content of the memory block will be initialized to zero.

Complement of free(long, long). Memory allocated by this method should be freed using free(long, long)

Specified by:

allocate in interface com.hazelcast.internal.memory.MemoryAllocator

Parameters:

size - of requested memory block

Returns:

address of memory block

Throws:

NativeOutOfMemoryError - if not enough memory is available

free

void free(long address,
          long size)

Gives allocated memory block back to internal pool or to OS if pool is over capacity.

Complement of allocate(long). Only memory allocated by allocate(long) can be freed using this method.

Specified by:

free in interface com.hazelcast.internal.memory.MemoryAllocator

Parameters:

address - address of memory block

size - size of memory block

getSystemAllocator

com.hazelcast.internal.memory.MemoryAllocator getSystemAllocator()

Returns:

the metadata memory allocator.

compact

void compact()

Compacts the memory region.

isDisposed

boolean isDisposed()

Gets the disposed state of this memory manager.

Returns:

true if this memory manager is destroyed, false otherwise

getMemoryStats

com.hazelcast.memory.MemoryStats getMemoryStats()

getUsableSize

long getUsableSize(long address)

Returns size of memory block as if it belongs to and is allocated by this memory manager. If memory block is not known by this memory manager, SIZE_INVALID is returned.

Parameters:

address - address of memory block

Returns:

size of memory block or SIZE_INVALID if it's unknown

validateAndGetUsableSize

long validateAndGetUsableSize(long address)

Returns size of memory block if and only if it belongs to and is allocated by this memory manager. Otherwise, if memory block is not valid anymore or it is not known by this memory manager, SIZE_INVALID is returned.

Parameters:

address - address of memory block

Returns:

size of memory block or SIZE_INVALID if it's unknown

getAllocatedSize

long getAllocatedSize(long address)

Returns allocated size of memory block as if it belongs to and is allocated by this memory manager. If memory block is not known by this memory manager, SIZE_INVALID is returned.

Allocated size includes usable memory size plus any header or metadata region size reserved by memory manager.

Parameters:

address - address of memory block

Returns:

size of memory block or SIZE_INVALID if it's unknown

See Also:

getUsableSize(long)

validateAndGetAllocatedSize

long validateAndGetAllocatedSize(long address)

Returns allocated size of memory block if and only if it belongs to and is allocated by this memory manager. Otherwise, if memory block is not valid anymore or it is not known by this memory manager, SIZE_INVALID is returned.

Allocated size includes usable memory size plus any header or metadata region size reserved by memory manager.

Parameters:

address - address of memory block

Returns:

size of memory block or SIZE_INVALID if it's unknown

See Also:

validateAndGetUsableSize(long)

newSequence

long newSequence()

Creates a new sequence. This sequence is guaranteed to be atomically incremental.

Use case for this sequence is to avoid ABA problem by using it with the address to create a "safe pointer" (address, sequence) to a memory block.

Returns:

new sequence