javax.realtime
Class MemoryArea

java.lang.Object
  |
  +--javax.realtime.MemoryArea

Direct Known Subclasses:

HeapMemory, ImmortalMemory, ImmortalPhysicalMemory, ScopedMemory

public abstract class MemoryArea

extends java.lang.Object

MemoryArea is the abstract base class of all classes dealing with the representations of allocatable memory areas, including the immortal memory area, physical memory and scoped memory areas.

Constructor Summary

protected	MemoryArea(long sizeInBytes)
protected	MemoryArea(long sizeInBytes, java.lang.Runnable logic)
protected	MemoryArea(SizeEstimator size)
protected	MemoryArea(SizeEstimator size, java.lang.Runnable logic)

Method Summary

void	enter() Associate this memory area to the current real-time thread for the duration of the execution of the run() method of the java.lang.Runnable passed at construction time.
void	enter(java.lang.Runnable logic) Associate this memory area to the current real-time thread for the duration of the execution of the run() method of the given java.lang.Runnable.
void	executeInArea(java.lang.Runnable logic) Execute the run method from the logic parameter using this memory area as the current allocation context.
static MemoryArea	getMemoryArea(java.lang.Object object) Returns the MemoryArea in which the given object is located.
long	memoryConsumed() An exact count, in bytes, of the all of the memory currently used by the system for the allocated objects.
long	memoryRemaining() An approximation to the total amount of memory currently available for future allocated objects, measured in bytes.
java.lang.Object	newArray(java.lang.Class type, int number) Allocate an array of T in this memory area.
java.lang.Object	newInstance(java.lang.Class type) Allocate an object in this memory area.
java.lang.Object	newInstance(java.lang.reflect.Constructor c, java.lang.Object[] args) Allocate an object in this memory area.
long	size() Query the size of the memory area.

Methods inherited from class java.lang.Object

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

Constructor Detail

MemoryArea

protected MemoryArea(long sizeInBytes)

Parameters:

sizeInBytes - The size of MemoryArea to allocate, in bytes.

MemoryArea

protected MemoryArea(SizeEstimator size)

Parameters:

size - A SizeEstimator object which indicates the amount of memory required by this MemoryArea.

MemoryArea

protected MemoryArea(long sizeInBytes,
                     java.lang.Runnable logic)

Parameters:

sizeInBytes - The size of MemoryArea to allocate, in bytes.

logic - The run() method of this object will be called whenever enter() is called.

MemoryArea

protected MemoryArea(SizeEstimator size,
                     java.lang.Runnable logic)

Parameters:

size - A SizeEstimator object which indicates the amount of memory required by this MemoryArea.

logic - The run() method of this object will be called whenever enter() is called.

Method Detail

enter

public void enter()
           throws ScopedCycleException

Associate this memory area to the current real-time thread for the duration of the execution of the run() method of the java.lang.Runnable passed at construction time. During this bound period of execution, all objects are allocated from the memory area until another one takes effect, or the enter() method is exited. A runtime exception is thrown if this method is called from thread other than a RealtimeThread or NoHeapRealtimeThread.

Throws:

java.lang.IllegalArgumentException - Thrown if no Runnable was passed in the constructor.

ScopedCycleException - If entering this ScopedMemory would violate the single parent rule.

enter

public void enter(java.lang.Runnable logic)
           throws ScopedCycleException

Associate this memory area to the current real-time thread for the duration of the execution of the run() method of the given java.lang.Runnable. During this bound period of execution, all objects are allocated from the memory area until another one takes effect, or the enter() method is exited. A runtime exception is thrown if this method is called from thread other than a RealtimeThread or NoHeapRealtimeThread.

Parameters:

logic - The Runnable object whose run() method should be invoked.

Throws:

ScopedCycleException - If entering this ScopedMemory would violate the single parent rule.

getMemoryArea

public static MemoryArea getMemoryArea(java.lang.Object object)

Returns the MemoryArea in which the given object is located.

Returns:

The MemoryArea of the object.

memoryConsumed

public long memoryConsumed()

An exact count, in bytes, of the all of the memory currently used by the system for the allocated objects.

Returns:

The amount of memory consumed in bytes.

memoryRemaining

public long memoryRemaining()

An approximation to the total amount of memory currently available for future allocated objects, measured in bytes.

Returns:

The amount of remaining memory in bytes

newArray

public java.lang.Object newArray(java.lang.Class type,
                                 int number)
                          throws java.lang.IllegalAccessException,
                                 java.lang.InstantiationException

Allocate an array of T in this memory area.

Parameters:

type - The class of the elements of the new array.

number - The number of elements in the new array.

Returns:

A new array of class type, of number elements.

Throws:

java.lang.IllegalAccessException - The class or initializer is inaccessible.

java.lang.InstantiationException - The array cannot be instantiated.

OutOfMemoryError - Space in the memory area is exhausted.

newInstance

public java.lang.Object newInstance(java.lang.Class type)
                             throws java.lang.IllegalAccessException,
                                    java.lang.InstantiationException

Allocate an object in this memory area.

Parameters:

type - The class of which to create a new instance.

Returns:

A new instance of class type.

Throws:

java.lang.IllegalAccessException - The class or initializer is inaccessible.

java.lang.InstantiationException - The specified class object could not be instantiated. Possible causes are: it is an interface, it is abstract, it is an array, or an exception was thrown by the constructor.

OutOfMemoryError - Space in the memory area is exhausted.

newInstance

public java.lang.Object newInstance(java.lang.reflect.Constructor c,
                                    java.lang.Object[] args)
                             throws java.lang.IllegalAccessException,
                                    java.lang.InstantiationException

Allocate an object in this memory area.

Parameters:

type - The class of which to create a new instance.

Returns:

A new instance of class type.

Throws:

java.lang.IllegalAccessException - The class or initializer is inaccessible.

java.lang.InstantiationException - The specified class object could not be instantiated. Possible causes are: it is an interface, it is abstract, it is an array, or an exception was thrown by the constructor.

OutOfMemoryError - Space in the memory area is exhausted.

size

public long size()

Query the size of the memory area. The returned value is the current size. Current size may be larger than initial size for those areas that are allowed to grow.

Returns:

The size of the memory area in bytes.

executeInArea

public void executeInArea(java.lang.Runnable logic)
                   throws InaccessibleAreaException

Execute the run method from the logic parameter using this memory area as the current allocation context. If the memory area is a scoped memory type, this method behaves as if it had moved the allocation context up the scope stack to the occurrence of the memory area. If the memory area is heap or immortal memory, this method behaves as if the run method were running in that memory type with an empty scope stack.

Parameters:

logic - The runnable object whose run() method should be executed.

Throws:

IllegalStateException - A non-realtime thread attempted to enter the memory area.

InaccessibleAreaException - The memory area is not in the thread's scope stack.