javax.realtime

Class RealtimeSystem

java.lang.Object

javax.realtime.RealtimeSystem

public final class RealtimeSystem
extends java.lang.Object

RealtimeSystem provides a means for tuning the behavior of the implementation by specifying parameters such as the maximum number of locks that can be in use concurrently, and the monitor control policy. In addition, RealtimeSystem provides a mechanism for obtaining access to the security manager, garbage collector, and scheduler, to query or set parameters.

Field Summary

Fields

Modifier and Type	Field and Description
static byte	BIG_ENDIAN Deprecated. RTSJ 2.0
static byte	BYTE_ORDER Deprecated. RTSJ 2.0
static byte	LITTLE_ENDIAN Deprecated. RTSJ 2.0

Method Summary

Modifier and Type	Method and Description
static boolean	canEnforceAllocationRate() Determines whether or not allocation rate enforcement is supported.
static boolean	canEnforceCost() Determines whether or not hard cost enforcement is supported.
static GarbageCollector	currentGC() Returns a reference to the currently active garbage collector for the heap.
static int	getConcurrentLocksUsed() Gets the maximum number of locks that have been used concurrently.
static MonitorControl	getInitialMonitorControl() Returns the monitor control object that represents the initial monitor control policy.
static int	getMaximumConcurrentLocks() Gets the maximum number of locks that can be used concurrently without incurring an execution time increase as set by the setMaximumConcurrentLocks() methods.
static RealtimeSecurity	getSecurityManager() Deprecated. since RTSJ 2.0
static boolean	hasUniversalClock() Determines whether or not this system supports a universal time clock.
static int	modules() The set of modules supported.
static void	setMaximumConcurrentLocks(int numLocks) Sets the anticipated maximum number of locks that may be held or waited on concurrently.
static void	setMaximumConcurrentLocks(int number, boolean hard) Sets the anticipated maximum number of locks that may be held or waited on concurrently.
static void	setSecurityManager(RealtimeSecurity manager) Sets a new realtime security manager.
static boolean	supports(RTSJModule module) Determines whether or not a particular module is supported.

Methods inherited from class java.lang.Object

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

Field Detail

BIG_ENDIAN

@Deprecated
public static final byte BIG_ENDIAN

Deprecated. RTSJ 2.0

Value indicating that the highest order byte of a bit word is stored at the lowest byte address: the int 0x0A0B0C0D is stored in the byte sequence 0x0A, 0x0B, 0x0C, 0x0D. and the long 0x0102030405060708 is stored in the sequence 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08.

LITTLE_ENDIAN

@Deprecated
public static final byte LITTLE_ENDIAN

Deprecated. RTSJ 2.0

Value indicating that the lowest order byte of a word is stored at the lowest byte address: the int 0x0A0B0C0D is stored in the byte sequence 0x0D, 0x0C, 0x0B, 0x0A and the long 0x0102030405060708 is stored in the sequence 0x08, 0x07, 0x06, 0x05, 0x04, 0x03, 0x02, 0x01.

BYTE_ORDER

@Deprecated
public static final byte BYTE_ORDER

Deprecated. RTSJ 2.0

The byte ordering of the underlying hardware.

Method Detail

currentGC

public static GarbageCollector currentGC()

Returns a reference to the currently active garbage collector for the heap.

Returns:

a GarbageCollector object which is the current collector collecting objects on the conventional Java heap.

getConcurrentLocksUsed

public static int getConcurrentLocksUsed()

Gets the maximum number of locks that have been used concurrently. This value can be used for tuning the concurrent locks parameter, which is used as a hint by systems that use a monitor cache.

Returns:

an integer, whose value is the maximum number of locks that have been used concurrently. When the number of concurrent locks is not tracked by the implementation, returns -1. Note that when the number of concurrent locks is not tracked, the number of available concurrent locks is effectively unlimited.

getMaximumConcurrentLocks

public static int getMaximumConcurrentLocks()

Gets the maximum number of locks that can be used concurrently without incurring an execution time increase as set by the setMaximumConcurrentLocks() methods.

Note that any relationship between this method and setMaximumConcurrentLocks is implementation-specific. This method returns the actual maximum number of concurrent locks the platform can currently support, or Integer.MAX_VALUE when there is no maximum. The setMaximumConcurrentLocks method gives the implementation a hint as to the maximum number of concurrent locks it should expect.

Returns:

an integer, whose value is the maximum number of locks that can be in simultaneous use.

getSecurityManager

@Deprecated
public static RealtimeSecurity getSecurityManager()

Deprecated. since RTSJ 2.0

Gets a reference to the security manager used to control access to realtime system features such as access to physical memory.

Returns:

a RealtimeSecurity object representing the default realtime security manager.

setMaximumConcurrentLocks

public static void setMaximumConcurrentLocks(int numLocks)

Sets the anticipated maximum number of locks that may be held or waited on concurrently. Provides a hint to systems that use a monitor cache as to how much space to dedicate to the cache.

Parameters:

numLocks - An integer, whose value becomes the number of locks that can be in simultaneous use without incurring an execution time increase. When number is less than or equal to zero nothing happens. When the system does not use this hint this method has no effect other than on the value returned by getMaximumConcurrentLocks().

setMaximumConcurrentLocks

public static void setMaximumConcurrentLocks(int number,
                                             boolean hard)

Sets the anticipated maximum number of locks that may be held or waited on concurrently. Provides a limit for the size of the monitor cache on systems that provide one when hard is true.

Parameters:

number - The maximum number of locks that can be in simultaneous use without incurring an execution time increase. When number is less than or equal to zero nothing happens. When the system does not use this hint this method has no effect other than on the value returned by getMaximumConcurrentLocks().

hard - When true, number sets a limit. When a lock is attempted which would cause the number of locks to exceed number then a ResourceLimitError is thrown. When the system does not limit use of concurrent locks, this parameter is silently ignored.

setSecurityManager

public static void setSecurityManager(RealtimeSecurity manager)

Sets a new realtime security manager.

Parameters:

manager - A RealtimeSecurity object which will become the new security manager.

Throws:

StaticSecurityException - when security manager has already been set.

getInitialMonitorControl

public static MonitorControl getInitialMonitorControl()

Returns the monitor control object that represents the initial monitor control policy.

Returns:

the initial monitor control policy.

Since:

RTSJ 1.0.1

supports

public static boolean supports(RTSJModule module)

Determines whether or not a particular module is supported.

Parameters:

module - The identifier of the module to be checked for support.

Returns:

true when module is supported; otherwise false.

Since:

RTSJ 2.0

modules

public static int modules()

The set of modules supported.

Returns:

an integer representing all the modules supported.

Since:

RTSJ 2.0

hasUniversalClock

public static boolean hasUniversalClock()

Determines whether or not this system supports a universal time clock.

Returns:

true when the system can provide a universal time clock.

canEnforceCost

public static boolean canEnforceCost()

Determines whether or not hard cost enforcement is supported.

Returns:

true when cost enforcement is supported; otherwise false.

Since:

RTSJ 2.0

canEnforceAllocationRate

public static boolean canEnforceAllocationRate()

Determines whether or not allocation rate enforcement is supported.

Returns:

true when allocation rate enforcement is supported, otherwise false.

Since:

RTSJ 2.0