com.oracle.svm.core.posix.linux

Class LinuxImageHeapProvider

java.lang.Object

com.oracle.svm.core.posix.linux.LinuxImageHeapProvider

All Implemented Interfaces:

ImageHeapProvider

public class LinuxImageHeapProvider
extends Object
implements ImageHeapProvider

An optimal image heap provider for Linux which creates isolate image heaps that retain the copy-on-write, lazy loading and reclamation semantics provided by the original heap's backing resource. This is accomplished by discovering the backing executable or shared object file the kernel has mmapped to the original heap image virtual address, as well as the location in the file storing the original heap. A new memory map is created to a new virtual range pointing to this same location. This allows the kernel to share the same physical pages between multiple heaps that have not been modified, as well as lazily load them only when needed. The implementation avoids dirtying the pages of the original, and only referencing what is strictly required.

Field Summary

Fields

Modifier and Type	Field and Description
static CGlobalData<org.graalvm.word.Pointer>	MAGIC Magic value to verify that a located image file matches our loaded image.

Constructor Summary

Constructors

Constructor and Description
LinuxImageHeapProvider()

Method Summary

Modifier and Type	Method and Description
int	freeImageHeap(org.graalvm.word.PointerBase imageHeap) Disposes an instance of the image heap that was created with this provider.
boolean	guaranteesHeapPreferredAddressSpaceAlignment() Returns whether this provider, when not already supplied a reserved address space by CommittedMemoryProvider, will always ensure a heap address space alignment of Heap.getPreferredAddressSpaceAlignment() at image runtime.
int	initialize(org.graalvm.word.Pointer reservedAddressSpace, org.graalvm.word.UnsignedWord reservedSize, org.graalvm.nativeimage.c.type.WordPointer basePointer, org.graalvm.nativeimage.c.type.WordPointer endPointer) Creates a new instance of the image heap.

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.oracle.svm.core.os.ImageHeapProvider

get

Field Detail

MAGIC

public static final CGlobalData<org.graalvm.word.Pointer> MAGIC

Magic value to verify that a located image file matches our loaded image.

Constructor Detail

LinuxImageHeapProvider

public LinuxImageHeapProvider()

Method Detail

guaranteesHeapPreferredAddressSpaceAlignment

public boolean guaranteesHeapPreferredAddressSpaceAlignment()

Description copied from interface: ImageHeapProvider

Returns whether this provider, when not already supplied a reserved address space by CommittedMemoryProvider, will always ensure a heap address space alignment of Heap.getPreferredAddressSpaceAlignment() at image runtime.

Specified by:

guaranteesHeapPreferredAddressSpaceAlignment in interface ImageHeapProvider

initialize

public int initialize(org.graalvm.word.Pointer reservedAddressSpace,
                      org.graalvm.word.UnsignedWord reservedSize,
                      org.graalvm.nativeimage.c.type.WordPointer basePointer,
                      org.graalvm.nativeimage.c.type.WordPointer endPointer)

Description copied from interface: ImageHeapProvider

Creates a new instance of the image heap.

Specified by:

initialize in interface ImageHeapProvider

Parameters:

reservedAddressSpace - If non-null, this specifies the address of a contiguous block of memory in which the image heap and the Java heap should be placed. If null, the ImageHeapProvider is responsible for allocating sufficient memory for the image heap at an arbitrary address.

reservedSize - If reservedAddressSpace is non-null, the number of reserved bytes at that address.

basePointer - An address where a pointer to the start address of the image heap instance will be written. Must not be null.

endPointer - An address where a pointer to the end of the image heap instance will be written. May be null if this value is not required.

Returns:

a result code from CEntryPointErrors.

freeImageHeap

public int freeImageHeap(org.graalvm.word.PointerBase imageHeap)

Description copied from interface: ImageHeapProvider

Disposes an instance of the image heap that was created with this provider. This method must only be called if the image heap memory was allocated by the ImageHeapProvider.

Specified by:

freeImageHeap in interface ImageHeapProvider