javax.safetycritical

Interface AllocationContext

All Known Implementing Classes:

ImmortalMemory, ManagedMemory, MemoryArea, MissionMemory, PrivateMemory

@SCJAllowed
public interface AllocationContext

This is the base interface for all memory areas.
It is a generalization of the Java Heap to allow for alternate forms of memory management.
All memory areas implement this interface.

Version:

1.0; - May 2012

Author:

Anders P. Ravn, Aalborg University, apr@cs.aau.dk,
Hans Søndergaard, VIA University College, Denmark, hso@viauc.dk

Relative_to_SCJ_Draft_Version_0.79:

- semantic issue: Why is this interface introduced as a public entity? No applications declare or access memory areas?
- semantic issue: IllegalThreadStateException (cf. SCJ Draft D.1.1 INTERFACE AllocationContext) is not included, since only infrastructure can invoke enter methods
- semantic issue: ThrowBoundaryError is not included. It must be the responsibility of the exception handlers for enter methods to make a local copy of the exception before propagating it.
- semantic issue: should newArray and newInstance be SCJAllowed. Should they be there at all?

Method Summary

Methods

Modifier and Type	Method and Description
void	executeInArea(java.lang.Runnable logic) Executes some logic with this memory area as the default allocation context.
long	memoryConsumed() Gets the amount of allocated memory in this memory area.
long	memoryRemaining() Gets the amount of memory available for allocation in this memory area.
java.lang.Object	newArray(java.lang.Class type, int number) Creates a new array of the given type in this memory area.
java.lang.Object	newInstance(java.lang.Class type) Creates a new instance of a class in this memory area using its default constructor.
long	size() Gets the size of this memory area.

Method Detail

executeInArea

@SCJAllowed(value=INFRASTRUCTURE)
void executeInArea(java.lang.Runnable logic)
                   throws java.lang.IllegalArgumentException

Executes some logic with this memory area as the default allocation context. The effect on the scope stack is specified in the implementing classes.

Parameters:

logic - is the runnable object whose run() method should be executed in this memory area.

Throws:

java.lang.IllegalArgumentException - Thrown if logic is null.

memoryConsumed

@SCJAllowed
long memoryConsumed()

Gets the amount of allocated memory in this memory area.

Returns:

The amount of memory consumed in bytes.

memoryRemaining

@SCJAllowed
long memoryRemaining()

Gets the amount of memory available for allocation in this memory area.

Returns:

The amount of memory remaining in bytes.

newArray

@SCJAllowed(value=INFRASTRUCTURE)
java.lang.Object newArray(java.lang.Class type,
                                                      int number)
                          throws java.lang.IllegalArgumentException,
                                 java.lang.OutOfMemoryError

Creates a new array of the given type in this memory area. This method may be concurrently used by multiple threads.

Parameters:

type - is the class of object this array should hold

number - is the number of elements the array should have.

Returns:

The new array of type type and size number.

Throws:

java.lang.IllegalArgumentException - Thrown when number is negative or type is null

java.lang.OutOfMemoryError - Thrown when there is not enough memory left.

newInstance

@SCJAllowed(value=INFRASTRUCTURE)
java.lang.Object newInstance(java.lang.Class type)
                             throws java.lang.IllegalAccessException,
                                    java.lang.InstantiationException,
                                    java.lang.OutOfMemoryError

Creates a new instance of a class in this memory area using its default constructor.

Parameters:

type - is the class of object to be created

Returns:

An object of class type.

Throws:

java.lang.IllegalAccessException

java.lang.InstantiationException

java.lang.OutOfMemoryError - Thrown when there is not enough memory left.

size

@SCJAllowed
long size()

Gets the size of this memory area.

Returns:

The current size of this memory area.