javax.realtime
Class NoHeapRealtimeThread

java.lang.Object
  |
  +--java.lang.Thread
        |
        +--javax.realtime.RealtimeThread
              |
              +--javax.realtime.NoHeapRealtimeThread

All Implemented Interfaces:

java.lang.Runnable, Schedulable

public class NoHeapRealtimeThread

extends RealtimeThread

A NoHeapRealtimeThread is a specialized form of RealtimeThread. Because an instance of NoHeapRealtimeThread may immediately preempt any implemented garbage collector logic contained in its run() is never allowed to allocate or reference any object allocated in the heap nor is it even allowed to manipulate any reference to any object in the heap. For example, if a and b are objects in immortal memory, b.p is reference to an object on the heap, and a.p is type compatible with b.p, then a NoHeapRealtimeThread is not allowed to execute anything like the following:

a.p = b.p; b.p = null;

Thus, it is always safe for a NoHeapRealtimeThread to interrupt the garbage collector at any time, without waiting for the end of the garbage collection cycle or a defined preemption point. Due to these restrictions, a NoHeapRealtimeThread object must be placed in a memory area such that thread logic may unexceptionally access instance variables and such that Java methods on Thread (e.g., enumerate and join) complete normally except where execution would cause access violations. The constructors of NoHeapRealtimeThread require a reference to ScopedMemory or ImmortalMemory.

When the thread is started, all execution occurs in the scope of the given memory area. Thus, all memory allocation performed with the "new" operator is taken from this given area.

Parameters for constructors may be null. In such cases the default value will be the default value set for the particular type by the associated instance of Scheduler.

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

NoHeapRealtimeThread(SchedulingParameters sp, MemoryArea ma)
Create a NoHeapRealtimeThread.

NoHeapRealtimeThread(SchedulingParameters sp, ReleaseParameters rp, MemoryArea ma)
Create a NoHeapRealtimeThread.

NoHeapRealtimeThread(SchedulingParameters sp, ReleaseParameters rp, MemoryParameters mp, MemoryArea ma, ProcessingGroupParameters group, java.lang.Runnable logic)
Create a NoHeapRealtimeThread.

Method Summary

void	start() Checks if the NoHeapRealtimeThread is startable and starts it if it is.

Methods inherited from class javax.realtime.RealtimeThread

addIfFeasible, addToFeasibility, currentRealtimeThread, deschedulePeriodic, getCurrentMemoryArea, getInitialMemoryAreaIndex, getMemoryAreaStackDepth, getMemoryParameters, getOuterMemoryArea, getProcessingGroupParameters, getReleaseParameters, getScheduler, getSchedulingParameters, interrupt, removeFromFeasibility, schedulePeriodic, setIfFeasible, setIfFeasible, setIfFeasible, setMemoryParameters, setMemoryParametersIfFeasible, setProcessingGroupParameters, setProcessingGroupParametersIfFeasible, setReleaseParameters, setReleaseParametersIfFeasible, setScheduler, setScheduler, setSchedulingParameters, setSchedulingParametersIfFeasible, sleep, sleep, waitForNextPeriod

Methods inherited from class java.lang.Thread

activeCount, checkAccess, countStackFrames, currentThread, destroy, dumpStack, enumerate, getContextClassLoader, getName, getPriority, getThreadGroup, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, run, setContextClassLoader, setDaemon, setName, setPriority, sleep, sleep, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Runnable

run

Constructor Detail

NoHeapRealtimeThread

public NoHeapRealtimeThread(SchedulingParameters sp,
                            MemoryArea ma)
                     throws java.lang.IllegalArgumentException

Create a NoHeapRealtimeThread.

Parameters:

scheduling - A SchedulingParameters object that will be associated with this. A null value means this will not have an associated SchedulingParameters object.

area - A MemoryArea object. Must be a ScopedMemory or ImmortalMemory type. A null value causes an IllegalArgumentException to be thrown.

NoHeapRealtimeThread

public NoHeapRealtimeThread(SchedulingParameters sp,
                            ReleaseParameters rp,
                            MemoryArea ma)
                     throws java.lang.IllegalArgumentException

Create a NoHeapRealtimeThread.

Parameters:

scheduling - A SchedulingParameters object that will be associated with this. A null value means this will not have an associated SchedulingParameters object.

release - A ReleaseParameters object that will be associated with this. A null value means this will not have an associated ReleaseParameters object.

area - A MemoryArea object. Must be a ScopedMemory or ImmortalMemory type. A null value causes an IllegalArgumentException to be thrown.

NoHeapRealtimeThread

public NoHeapRealtimeThread(SchedulingParameters sp,
                            ReleaseParameters rp,
                            MemoryParameters mp,
                            MemoryArea ma,
                            ProcessingGroupParameters group,
                            java.lang.Runnable logic)
                     throws java.lang.IllegalArgumentException

Create a NoHeapRealtimeThread.

Parameters:

scheduling - A SchedulingParameters object that will be associated with this. A null value means this will not have an associated SchedulingParameters object.

release - A ReleaseParameters object that will be associated with this. A null value means this will not have an associated ReleaseParameters object.

memory - A MemoryParameters object that will be associated with this. A null value means this will not have a MemoryParameters object.

area - A MemoryArea object. Must be a ScopedMemory or ImmortalMemory type. A null value causes an IllegalArgumentException to be thrown.

group - A ProcessingGroupParameters object that will be associated with this. A null value means this will not have an associated ProcessingGroupParameters object.

logic - A Runnable whose run() method will be executed for this.

Method Detail

start

public void start()

Checks if the NoHeapRealtimeThread is startable and starts it if it is. Checks that the parameters associated with this NHRT object are not allocated in heap. Also checks if this object is allocated in heap. If any of them are allocated, start() throws a MemoryAccessError

Overrides:

start in class RealtimeThread

Throws:

MemoryAccessError - If any of the parameters or this is allocated on heap.