com.espertech.esper.epl.db

Class DatabasePollingViewable

java.lang.Object

com.espertech.esper.epl.db.DatabasePollingViewable

All Implemented Interfaces:

StopCallback, EventCollection, HistoricalEventViewable, ValidatedView, Viewable, Iterable<EventBean>

public class DatabasePollingViewable
extends Object
implements HistoricalEventViewable

Implements a poller viewable that uses a polling strategy, a cache and some input parameters extracted from event streams to perform the polling.

Constructor Summary

Constructors

Constructor and Description
DatabasePollingViewable(int myStreamNumber, List<String> inputParameters, PollExecStrategy pollExecStrategy, DataCache dataCache, EventType eventType) Ctor.

Method Summary

Modifier and Type	Method and Description
View	addView(View view) Add a view to the viewable object.
ThreadLocal<DataCache>	getDataCacheThreadLocal() Historical views are expected to provide a thread-local data cache for use in keeping row (EventBean references) returned during iteration stable, since the concept of a primary key does not exist.
EventType	getEventType() Provides metadata information about the type of object the event collection contains.
DataCache	getOptionalDataCache()
SortedSet<Integer>	getRequiredStreams() Returns the a set of stream numbers of all streams that provide property values in any of the parameter expressions to the stream.
View[]	getViews() Returns all added views.
boolean	hasRequiredStreams() Returns true if the parameters expressions to the historical require other stream's data, or false if there are no parameters or all parameter expressions are only contants and variables without properties of other stream events.
boolean	hasViews() Test is there are any views to the Viewable.
Iterator<EventBean>	iterator() Allows iteration through all elements in this event collection.
EventTable[][]	poll(EventBean[][] lookupEventsPerStream, PollResultIndexingStrategy indexingStrategy, ExprEvaluatorContext exprEvaluatorContext) Poll for stored historical or reference data using events per stream and returing for each event-per-stream row a separate list with events representing the poll result.
void	removeAllViews() Remove all views.
boolean	removeView(View view) Remove a view.
void	stop() Stops the underlying resources.
void	validate(EngineImportService engineImportService, StreamTypeService streamTypeService, TimeProvider timeProvider, VariableService variableService, TableService tableService, ExprEvaluatorContext exprEvaluatorContext, ConfigurationInformation configSnapshot, SchedulingService schedulingService, String engineURI, Map<Integer,List<ExprNode>> sqlParameters, EventAdapterService eventAdapterService, StatementContext statementContext) Validate the view.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Constructor Detail

DatabasePollingViewable

public DatabasePollingViewable(int myStreamNumber,
                               List<String> inputParameters,
                               PollExecStrategy pollExecStrategy,
                               DataCache dataCache,
                               EventType eventType)

Ctor.

Parameters:

myStreamNumber - is the stream number of the view

inputParameters - are the event property names providing input parameter keys

pollExecStrategy - is the strategy to use for retrieving results

dataCache - is looked up before using the strategy

eventType - is the type of events generated by the view

Method Detail

stop

public void stop()

Description copied from interface: StopCallback

Stops the underlying resources.

Specified by:

stop in interface StopCallback

getOptionalDataCache

public DataCache getOptionalDataCache()

Specified by:

getOptionalDataCache in interface HistoricalEventViewable

validate

public void validate(EngineImportService engineImportService,
                     StreamTypeService streamTypeService,
                     TimeProvider timeProvider,
                     VariableService variableService,
                     TableService tableService,
                     ExprEvaluatorContext exprEvaluatorContext,
                     ConfigurationInformation configSnapshot,
                     SchedulingService schedulingService,
                     String engineURI,
                     Map<Integer,List<ExprNode>> sqlParameters,
                     EventAdapterService eventAdapterService,
                     StatementContext statementContext)
              throws ExprValidationException

Description copied from interface: ValidatedView

Validate the view.

Specified by:

validate in interface ValidatedView

Parameters:

engineImportService - engine imports

streamTypeService - supplies the types of streams against which to validate

timeProvider - for providing current time

variableService - for access to variables

tableService - tables

exprEvaluatorContext - context for expression evaluation

configSnapshot - configuration

schedulingService - scheduling

engineURI - engine URI

sqlParameters - parameters

eventAdapterService - event type info

statementContext - statement context

Throws:

ExprValidationException - is thrown to indicate an exception in validating the view

poll

public EventTable[][] poll(EventBean[][] lookupEventsPerStream,
                           PollResultIndexingStrategy indexingStrategy,
                           ExprEvaluatorContext exprEvaluatorContext)

Description copied from interface: HistoricalEventViewable

Poll for stored historical or reference data using events per stream and returing for each event-per-stream row a separate list with events representing the poll result.

Specified by:

poll in interface HistoricalEventViewable

Parameters:

lookupEventsPerStream - is the events per stream where the first dimension is a number of rows (often 1 depending on windows used) and the second dimension is the number of streams participating in a join.

indexingStrategy - the strategy to use for converting poll results into a indexed table for fast lookup

exprEvaluatorContext - context for expression evalauation

Returns:

array of lists with one list for each event-per-stream row

addView

public View addView(View view)

Description copied from interface: Viewable

Add a view to the viewable object.

Specified by:

addView in interface Viewable

Parameters:

view - to add

Returns:

view to add

getViews

public View[] getViews()

Description copied from interface: Viewable

Returns all added views.

Specified by:

getViews in interface Viewable

Returns:

list of added views

removeView

public boolean removeView(View view)

Description copied from interface: Viewable

Remove a view.

Specified by:

removeView in interface Viewable

Parameters:

view - to remove

Returns:

true to indicate that the view to be removed existed within this view, false if the view to remove could not be found

hasViews

public boolean hasViews()

Description copied from interface: Viewable

Test is there are any views to the Viewable.

Specified by:

hasViews in interface Viewable

Returns:

true indicating there are child views, false indicating there are no child views

getEventType

public EventType getEventType()

Description copied from interface: EventCollection

Provides metadata information about the type of object the event collection contains.

Specified by:

getEventType in interface EventCollection

Returns:

metadata for the objects in the collection

iterator

public Iterator<EventBean> iterator()

Description copied from interface: EventCollection

Allows iteration through all elements in this event collection. The iterator will return the elements in the collection in their natural order, or, if there is no natural ordering, in some unpredictable order.

Specified by:

iterator in interface EventCollection

Specified by:

iterator in interface Iterable<EventBean>

Returns:

an iterator which will go through all current elements in the collection.

getRequiredStreams

public SortedSet<Integer> getRequiredStreams()

Description copied from interface: HistoricalEventViewable

Returns the a set of stream numbers of all streams that provide property values in any of the parameter expressions to the stream.

Specified by:

getRequiredStreams in interface HistoricalEventViewable

Returns:

set of stream numbers

hasRequiredStreams

public boolean hasRequiredStreams()

Description copied from interface: HistoricalEventViewable

Returns true if the parameters expressions to the historical require other stream's data, or false if there are no parameters or all parameter expressions are only contants and variables without properties of other stream events.

Specified by:

hasRequiredStreams in interface HistoricalEventViewable

Returns:

indicator whether properties are required for parameter evaluation

getDataCacheThreadLocal

public ThreadLocal<DataCache> getDataCacheThreadLocal()

Description copied from interface: HistoricalEventViewable

Historical views are expected to provide a thread-local data cache for use in keeping row (EventBean references) returned during iteration stable, since the concept of a primary key does not exist.

Specified by:

getDataCacheThreadLocal in interface HistoricalEventViewable

Returns:

thread-local cache, can be null for any thread to indicate no caching

removeAllViews

public void removeAllViews()

Description copied from interface: Viewable

Remove all views.

Specified by:

removeAllViews in interface Viewable