Package io.deephaven.engine.util

Class PrintListener

java.lang.Object

io.deephaven.util.referencecounting.ReferenceCounted

io.deephaven.engine.liveness.ReferenceCountedLivenessReferent

io.deephaven.engine.liveness.ReferenceCountedLivenessNode

io.deephaven.engine.liveness.LivenessArtifact

io.deephaven.engine.table.impl.InstrumentedTableListenerBase

io.deephaven.engine.table.impl.InstrumentedTableUpdateListener

io.deephaven.engine.util.PrintListener

All Implemented Interfaces:

LogOutputAppendable, LivenessManager, LivenessNode, LivenessReferent, TableListener, TableUpdateListener, NotificationQueue.Dependency, Serializable

@ScriptApi
public class PrintListener
extends InstrumentedTableUpdateListener

A simple listener that prints out each update received from a table.

This can be used to debug the performance of a query by attaching to various tables in an effort to understand the update pattern. Optionally, you can also print out the head of the table.

Output is directed to stdout, thus this should not be enabled in production queries.

After you are finished, call the stop() method to remove this listener from the source table.

See Also:

• Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class io.deephaven.engine.table.impl.InstrumentedTableUpdateListener

InstrumentedTableUpdateListener.Notification

Nested classes/interfaces inherited from class io.deephaven.engine.table.impl.InstrumentedTableListenerBase

InstrumentedTableListenerBase.ErrorNotification, InstrumentedTableListenerBase.NotificationBase

Nested classes/interfaces inherited from interface io.deephaven.engine.table.TableListener

TableListener.Entry

Constructor Summary

Constructors

Constructor	Description
PrintListener(String description, Table table)	Create a PrintListener attached to the given table.
PrintListener(String description, Table table, int rowCount)	Create a PrintListener attached to the given table.

Method Summary

Modifier and Type	Method	Description
void	onFailureInternal(Throwable originalException, TableListener.Entry sourceEntry)
void	onUpdate(TableUpdate upstream)	Process notification of table changes.
void	stop()	Remove this listener from the table.

Methods inherited from class io.deephaven.engine.table.impl.InstrumentedTableUpdateListener

getNotification

Methods inherited from class io.deephaven.engine.table.impl.InstrumentedTableListenerBase

append, canExecute, getEntry, getErrorNotification, getUpdateGraph, onFailure, onFailureInternalWithDependent, satisfied, setVerboseLogging, toString

Methods inherited from class io.deephaven.engine.liveness.LivenessArtifact

manageWithCurrentScope

Methods inherited from class io.deephaven.engine.liveness.ReferenceCountedLivenessNode

getWeakReference, initializeTransientFieldsForLiveness, onReferenceCountAtZero, tryManage, tryUnmanage, tryUnmanage

Methods inherited from class io.deephaven.engine.liveness.ReferenceCountedLivenessReferent

destroy, dropReference, tryRetainReference

Methods inherited from class io.deephaven.util.referencecounting.ReferenceCounted

decrementReferenceCount, forceReferenceCountToZero, getReferenceCountDebug, incrementReferenceCount, resetReferenceCount, tryDecrementReferenceCount, tryIncrementReferenceCount

Methods inherited from class java.lang.Object

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

Methods inherited from interface io.deephaven.engine.liveness.LivenessManager

manage, tryManage

Methods inherited from interface io.deephaven.engine.liveness.LivenessNode

tryUnmanage, tryUnmanage, unmanage, unmanage

Methods inherited from interface io.deephaven.engine.liveness.LivenessReferent

dropReference, getReferentDescription, getWeakReference, retainReference, tryRetainReference

Methods inherited from interface io.deephaven.engine.updategraph.NotificationQueue.Dependency

getUpdateGraph

Methods inherited from interface io.deephaven.engine.table.TableListener

getErrorNotification, onFailure

Constructor Details

PrintListener

@ScriptApi
public PrintListener(String description,
 Table table)

Create a PrintListener attached to the given table.

Parameters:

description - the description (for use in each print statement)

table - the table to attach to

PrintListener

@ScriptApi
public PrintListener(String description,
 Table table,
 int rowCount)

Create a PrintListener attached to the given table.

Parameters:

description - the description (for use in each print statement)

table - the table to attach to

rowCount - how many rows to print out on each update

Method Details

onUpdate

public void onUpdate(TableUpdate upstream)

Description copied from interface: TableUpdateListener

Process notification of table changes.

The TableUpdateListener onUpdate call executes within the UpdateGraph refresh loop. Any tables used within the listener's onUpdate call must have already been refreshed. Using the typical pattern of a Listener that is listening to a single table, with Table.addUpdateListener(TableUpdateListener), this is trivially true.

When the listener must reference more than just one parent, the tables (or other objects) it references, must be made a NotificationQueue.Dependency of the listener. For listeners that reference multiple ticking tables, a common pattern is to use a MergedListener and collection of ListenerRecorders.

Parameters:

upstream - The set of upstream table updates.

onFailureInternal

public void onFailureInternal(Throwable originalException,
 TableListener.Entry sourceEntry)

Specified by:

onFailureInternal in class InstrumentedTableListenerBase

stop

public void stop()

Remove this listener from the table.