com.espertech.esper.view.stream

Interface StreamFactoryService

All Known Implementing Classes:

StreamFactorySvcImpl

public interface StreamFactoryService

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.

We are re-using streams such that views under such streams can be reused for efficient resource use.

Method Summary

Modifier and Type	Method and Description
Pair<EventStream,StatementAgentInstanceLock>	createStream(int statementId, FilterSpecCompiled filterSpec, FilterService filterService, EPStatementAgentInstanceHandle epStatementAgentInstanceHandle, boolean isJoin, AgentInstanceContext agentInstanceContext, boolean hasOrderBy, boolean filterWithSameTypeSubselect, Annotation[] annotations, boolean stateless, int streamNum, boolean isCanIterateUnbound) Create or reuse existing EventStream instance representing that event filter.
void	destroy() Destroy the service.
void	dropStream(FilterSpecCompiled filterSpec, FilterService filterService, boolean isJoin, boolean hasOrderBy, boolean filterWithSameTypeSubselect, boolean stateless) Drop the event stream associated with the filter passed in.

Method Detail

createStream

Pair<EventStream,StatementAgentInstanceLock> createStream(int statementId,
                                                          FilterSpecCompiled filterSpec,
                                                          FilterService filterService,
                                                          EPStatementAgentInstanceHandle epStatementAgentInstanceHandle,
                                                          boolean isJoin,
                                                          AgentInstanceContext agentInstanceContext,
                                                          boolean hasOrderBy,
                                                          boolean filterWithSameTypeSubselect,
                                                          Annotation[] annotations,
                                                          boolean stateless,
                                                          int streamNum,
                                                          boolean isCanIterateUnbound)

Create or reuse existing EventStream instance representing that event filter. When called for some filters, should return same stream.

Parameters:

statementId - the statement id

filterSpec - event filter definition

filterService - filter service to activate filter if not already active

epStatementAgentInstanceHandle - is the statements-own handle for use in registering callbacks with services

isJoin - is indicatng whether the stream will participate in a join statement, information necessary for stream reuse and multithreading concerns

agentInstanceContext - expression evaluation context

hasOrderBy - if the consumer has order-by

annotations - annotations

filterWithSameTypeSubselect - whether filter and subselect type match

isCanIterateUnbound - whether we can iterate unbound

stateless - whether stateless

streamNum - stream number

Returns:

event stream representing active filter

dropStream

void dropStream(FilterSpecCompiled filterSpec,
                FilterService filterService,
                boolean isJoin,
                boolean hasOrderBy,
                boolean filterWithSameTypeSubselect,
                boolean stateless)

Drop the event stream associated with the filter passed in. Throws an exception if already dropped.

Parameters:

filterSpec - is the event filter definition associated with the event stream to be dropped

filterService - to be used to deactivate filter when the last event stream is dropped

isJoin - is indicatng whether the stream will participate in a join statement, information necessary for stream reuse and multithreading concerns

hasOrderBy - if the consumer has an order-by clause

filterWithSameTypeSubselect - whether filter and subselect event type match

stateless - whether stateless

destroy

void destroy()

Destroy the service.