/*
***************************************************************************************
* Copyright (C) 2006 EsperTech, Inc. All rights reserved. *
* http://www.espertech.com/esper *
* http://www.espertech.com *
* ---------------------------------------------------------------------------------- *
* The software in this package is published under the terms of the GPL license *
* a copy of which has been included with this distribution in the license.txt file. *
***************************************************************************************
*/
package com.espertech.esper.view.stream;
import com.espertech.esper.collection.Pair;
import com.espertech.esper.core.context.util.AgentInstanceContext;
import com.espertech.esper.core.context.util.EPStatementAgentInstanceHandle;
import com.espertech.esper.core.service.StatementAgentInstanceLock;
import com.espertech.esper.filter.FilterService;
import com.espertech.esper.filter.FilterSpecCompiled;
import com.espertech.esper.view.EventStream;
import java.lang.annotation.Annotation;
/**
* Service on top of the filter service for reuseing filter callbacks and their associated EventStream instances.
* Same filter specifications (equal) do not need to be added to the filter service twice and the
* EventStream instance that is the stream of events for that filter can be reused.
* <p>
* We are re-using streams such that views under such streams can be reused for efficient resource use.
*/
public interface StreamFactoryService {
/**
* Create or reuse existing EventStream instance representing that event filter.
* When called for some filters, should return same stream.
*
* @param statementId the statement id
* @param filterSpec event filter definition
* @param filterService filter service to activate filter if not already active
* @param epStatementAgentInstanceHandle is the statements-own handle for use in registering callbacks with services
* @param isJoin is indicatng whether the stream will participate in a join statement, information
* necessary for stream reuse and multithreading concerns
* @param agentInstanceContext expression evaluation context
* @param hasOrderBy if the consumer has order-by
* @param annotations annotations
* @param filterWithSameTypeSubselect whether filter and subselect type match
* @param isCanIterateUnbound whether we can iterate unbound
* @param stateless whether stateless
* @param streamNum stream number
* @return event stream representing active filter
*/
public Pair<EventStream, StatementAgentInstanceLock> createStream(final int statementId,
FilterSpecCompiled filterSpec,
FilterService filterService,
EPStatementAgentInstanceHandle epStatementAgentInstanceHandle,
boolean isJoin,
AgentInstanceContext agentInstanceContext,
boolean hasOrderBy,
boolean filterWithSameTypeSubselect,
Annotation[] annotations,
boolean stateless,
int streamNum,
boolean isCanIterateUnbound);
/**
* Drop the event stream associated with the filter passed in.
* Throws an exception if already dropped.
*
* @param filterSpec is the event filter definition associated with the event stream to be dropped
* @param filterService to be used to deactivate filter when the last event stream is dropped
* @param isJoin is indicatng whether the stream will participate in a join statement, information
* necessary for stream reuse and multithreading concerns
* @param hasOrderBy if the consumer has an order-by clause
* @param filterWithSameTypeSubselect whether filter and subselect event type match
* @param stateless whether stateless
*/
public void dropStream(FilterSpecCompiled filterSpec, FilterService filterService, boolean isJoin, boolean hasOrderBy, boolean filterWithSameTypeSubselect, boolean stateless);
/**
* Destroy the service.
*/
public void destroy();
}