Module org.praxislive.core

Package org.praxislive.core

Interface ExecutionContext

All Known Implementing Classes:

DefaultExecutionContext

public interface ExecutionContext

An optional context available from the Root lookup providing the ability to query and listen for changes in root state or clock time.

A Root will be initialized with ExecutionContext.State.NEW, move to / between ExecutionContext.State.ACTIVE and ExecutionContext.State.IDLE, then move to ExecutionContext.State.TERMINATED. A Root will not return to the NEW state, or any other state once terminated.

Time is the local Root time relative to RootHub.getClock(). Clock listeners are called whenever the Root's local time changes - the frequency of changes, and whether the frequency is fixed or variable, is Root implementation specific.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	ExecutionContext.ClockListener	Listener called on clock time updates.
static enum	ExecutionContext.State	Possible states of a Root.
static interface	ExecutionContext.StateListener	Listener called on state changes.

Method Summary

Modifier and Type	Method	Description
void	addClockListener(ExecutionContext.ClockListener listener)	Add a listener for clock changes.
void	addStateListener(ExecutionContext.StateListener listener)	Add a listener for state changes.
default OptionalLong	getPeriod()	Get the optional update period, if the Root implementation guarantees to update clock time at a fixed frequency.
long	getStartTime()	Get the clock time in nanoseconds when the Root last became active.
ExecutionContext.State	getState()	Get the current state of the Root.
long	getTime()	Get the current Root local time in nanoseconds, relative to the RootHub clock.
void	removeClockListener(ExecutionContext.ClockListener listener)	Remove an existing clock listener.
void	removeStateListener(ExecutionContext.StateListener listener)	Remove an existing state listener.

Method Details

addStateListener

void addStateListener(ExecutionContext.StateListener listener)

Add a listener for state changes.

Parameters:

listener - state listener, may not be null

removeStateListener

void removeStateListener(ExecutionContext.StateListener listener)

Remove an existing state listener.

Parameters:

listener - state listener to remove

addClockListener

void addClockListener(ExecutionContext.ClockListener listener)

Add a listener for clock changes. Listeners will be called every time the Root is active and its local time changes - the frequency of changes, and whether the frequency is fixed or variable, is Root implementation specific.

Parameters:

listener - clock listener, may not be null

removeClockListener

void removeClockListener(ExecutionContext.ClockListener listener)

Remove an existing clock listener.

Parameters:

listener - clock listener to remove

getTime

long getTime()

Get the current Root local time in nanoseconds, relative to the RootHub clock.

Returns:

time in nanoseconds

getStartTime

long getStartTime()

Get the clock time in nanoseconds when the Root last became active. If the current state is not active, the return value is not valid.

Returns:

clock time became active

getState

ExecutionContext.State getState()

Get the current state of the Root.

Returns:

current state

getPeriod

default OptionalLong getPeriod()

Get the optional update period, if the Root implementation guarantees to update clock time at a fixed frequency.

Returns:

optional update period