javax.realtime.memory

Class LTMemory

java.lang.Object

javax.realtime.MemoryArea

javax.realtime.memory.ScopedMemory

javax.realtime.memory.LTMemory

public class LTMemory
extends ScopedMemory

LTMemory represents a memory area guaranteed by the system to have linear time allocation when memory consumption from the memory area is less than the memory area's initial size. Execution time for allocation is allowed to vary when memory consumption is between the initial size and the maximum size for the area. Furthermore, the underlying system is not required to guarantee that memory between initial and maximum will always be available.

The memory area described by a LTMemory instance does not exist in the Java heap, and is not subject to garbage collection. Thus, it is safe to use a LTMemory object as the initial memory area for a Schedulable instance which may not use the HeapMemory or to enter the memory area using the ScopedMemory.enter() method within such an instance.

Enough memory must be committed by the completion of the constructor to satisfy the initial memory requirement. (Committed means that this memory must always be available for allocation). The initial memory allocation must behave, with respect to successful allocation, as if it were contiguous; i.e., a correct implementation must guarantee that any sequence of object allocations that could ever succeed without exceeding a specified initial memory size will always succeed without exceeding that initial memory size and succeed for any instance of LTMemory with that initial memory size.

Creation of an LTMemory shall fail with an StaticOutOfMemoryError when the current Schedulable has been configured with a ScopedMemoryParameters.getMaxGlobalBackingStore() that would be exceeded by said creation.

Note, to ensure that all requested memory is available set initial and maximum to the same value.

Methods from LTMemory should be overridden only by methods that use super.

Constructor Summary

Constructors

Constructor and Description
LTMemory(long size) Equivalent to LTMemory(long, Runnable) with the argument list ((size, null).
LTMemory(long size, Runnable logic) Create a scoped memory of the given size and with the give logic to run upon entry when no other logic is given.
LTMemory(SizeEstimator size) Equivalent to LTMemory(long, Runnable) with argument list (size.getEstimate(), null).
LTMemory(SizeEstimator size, Runnable logic) Equivalent to LTMemory(long, Runnable) with argument list (size.getEstimate(), runnable).

Method Summary

Methods inherited from class javax.realtime.memory.ScopedMemory

enter, enter, enter, enter, enter, enter, enter, executeInArea, executeInArea, executeInArea, executeInArea, executeInArea, executeInArea, finalize, getParent, getPortal, getReferenceCount, globalBackingStoreConsumed, globalBackingStoreRemaining, globalBackingStoreSize, join, join, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, joinAndEnter, mayHoldReferenceTo, mayHoldReferenceTo, setPortal, toString, visitNestedScopes, visitScopeRoots

Methods inherited from class javax.realtime.MemoryArea

getMemoryArea, memoryConsumed, memoryRemaining, newArray, newArrayInArea, newInstance, newInstance, size

Methods inherited from class java.lang.Object

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

Constructor Detail

LTMemory

public LTMemory(long size)

Equivalent to LTMemory(long, Runnable) with the argument list ((size, null).

Throws:

IllegalArgumentException - when size is less than zero.

StaticOutOfMemoryError - when there is insufficient memory for the LTMemory object or for the backing memory, or when the current Schedulable would exceed its configured allowance of global backing store.

UnsupportedOperationException - In JamaicaVM when a user-defined subclass does not know about the memory area implementation details.

Parameters:

size - The size in bytes of the memory to allocate for this area. This memory must be committed before the completion of the constructor.

Since:

RTSJ 1.0.1

LTMemory

public LTMemory(long size,
                Runnable logic)

Create a scoped memory of the given size and with the give logic to run upon entry when no other logic is given.

Throws:

IllegalArgumentException - when size is less than zero.

StaticOutOfMemoryError - when there is insufficient memory for the LTMemory object or for the backing memory, or when the current Schedulable would exceed its configured allowance of global backing store.

IllegalAssignmentError - when storing logic in this would violate the assignment rules.

UnsupportedOperationException - In JamaicaVM when a user-defined subclass does not know about the memory area implementation details.

Parameters:

size - The size in bytes of the memory to allocate for this area. This memory must be committed before the completion of the constructor.

logic - The run() of the given Runnable will be executed using this as its initial memory area. When logic is null, this constructor is equivalent to LTMemory(long).

Since:

RTSJ 1.0.1

LTMemory

public LTMemory(SizeEstimator size)

Equivalent to LTMemory(long, Runnable) with argument list (size.getEstimate(), null).

Throws:

IllegalArgumentException - when size is null.

StaticOutOfMemoryError - when there is insufficient memory for the LTMemory object or for the backing memory, or when the current Schedulable would exceed its configured allowance of global backing store.

UnsupportedOperationException - In JamaicaVM when a user-defined subclass does not know about the memory area implementation details.

Parameters:

size - An instance of SizeEstimator used to give an estimate of the initial size. This memory must be committed before the completion of the constructor.

Since:

RTSJ 1.0.1

LTMemory

public LTMemory(SizeEstimator size,
                Runnable logic)

Equivalent to LTMemory(long, Runnable) with argument list (size.getEstimate(), runnable).

Throws:

IllegalArgumentException - when size is null.

StaticOutOfMemoryError - when there is insufficient memory for the LTMemory object or for the backing memory, or when the current Schedulable would exceed its configured allowance of global backing store.

IllegalAssignmentError - when storing logic in this would violate the assignment rules.

UnsupportedOperationException - In JamaicaVM when a user-defined subclass does not know about the memory area implementation details.

Parameters:

size - An instance of SizeEstimator used to give an estimate of the initial size. This memory must be committed before the completion of the constructor.

logic - The run() of the given Runnable will be executed using this as its initial memory area. When logic is null, this constructor is equivalent to LTMemory(SizeEstimator).

Since:

RTSJ 1.0.1