org.neo4j.unsafe.impl.internal.dragons

Class MemoryManager

java.lang.Object

org.neo4j.unsafe.impl.internal.dragons.MemoryManager

public final class MemoryManager
extends Object

The memory manager is simple: it only allocates memory, until it itself is finalizable and frees it all in one go. The memory is allocated in large segments, and the memory returned by the memory manager is page aligned, and plays well with transparent huge pages and other operating system optimisations. The memory manager assumes that the memory claimed from it is evenly divisible in units of pages.

Constructor Summary

Constructors

Constructor and Description
MemoryManager(long expectedMaxMemory, long alignment) Create a new MemoryManager that will allocate the given amount of memory, to pointers that are aligned to the given alignment size.

Method Summary

Modifier and Type	Method and Description
long	allocateAligned(long bytes) Allocate a contiguous, aligned region of memory of the given size in bytes.

Methods inherited from class java.lang.Object

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

Constructor Detail

MemoryManager

public MemoryManager(long expectedMaxMemory,
                     long alignment)

Create a new MemoryManager that will allocate the given amount of memory, to pointers that are aligned to the given alignment size.

Parameters:

expectedMaxMemory - The maximum amount of memory that this memory manager is expected to allocate. The actual amount of memory used can end up greater than this value, if some of it gets wasted on alignment padding.

alignment - The byte multiple that the allocated pointers have to be aligned at.

Method Detail

allocateAligned

public long allocateAligned(long bytes)

Allocate a contiguous, aligned region of memory of the given size in bytes.

Parameters:

bytes - the number of bytes to allocate.

Returns:

A pointer to the allocated memory.