com.espertech.esper.view.stream

Class StreamFactorySvcImpl

java.lang.Object

com.espertech.esper.view.stream.StreamFactorySvcImpl

All Implemented Interfaces:

StreamFactoryService

public class StreamFactorySvcImpl
extends Object
implements StreamFactoryService

Service implementation to reuse or not reuse event streams and existing filters depending on the type of statement.

For non-join statements, the class manages the reuse of event streams when filters match, and thus when an event stream is reused such can be the views under the stream. For joins however, this can lead to problems in multithread-safety since the statement resource lock would then have to be multiple locks, i.e. the reused statement's resource lock and the join statement's own lock, at a minimum.

For join statements, always creating a new event stream and therefore not reusing view resources, for use with joins.

This can be very effective in that if a client applications creates a large number of very similar statements in terms of filters and views used then these resources are all re-used across statements.

The re-use is multithread-safe in that (A) statement start/stop is locked against other engine processing (B) the first statement supplies the lock for shared filters and views, protecting multiple threads from entering into the same view. (C) joins statements do not participate in filter and view reuse

Constructor Summary

Constructors

Constructor and Description
StreamFactorySvcImpl(String engineURI, boolean isReuseViews) Ctor.

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) See the method of the same name in StreamFactoryService.
void	destroy() Destroy the service.
void	dropStream(FilterSpecCompiled filterSpec, FilterService filterService, boolean isJoin, boolean hasOrderBy, boolean filterWithSameTypeSubselect, boolean stateless) See the method of the same name in StreamFactoryService.

Methods inherited from class java.lang.Object

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

Constructor Detail

StreamFactorySvcImpl

public StreamFactorySvcImpl(String engineURI,
                            boolean isReuseViews)

Ctor.

Parameters:

isReuseViews - indicator on whether stream and view resources are to be reused between statements

engineURI - engine URI

Method Detail

destroy

public void destroy()

Description copied from interface: StreamFactoryService

Destroy the service.

Specified by:

destroy in interface StreamFactoryService

createStream

public 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)

See the method of the same name in StreamFactoryService. Always attempts to reuse an existing event stream. May thus return a new event stream or an existing event stream depending on whether filter criteria match.

Specified by:

createStream in interface StreamFactoryService

Parameters:

filterSpec - is the filter definition

epStatementAgentInstanceHandle - is the statement resource lock

statementId - the statement id

filterService - filter service to activate filter if not already active

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

filterWithSameTypeSubselect - whether filter and subselect type match

annotations - annotations

stateless - whether stateless

streamNum - stream number

isCanIterateUnbound - whether we can iterate unbound

Returns:

newly createdStatement event stream, not reusing existing instances

dropStream

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

See the method of the same name in StreamFactoryService.

Specified by:

dropStream in interface StreamFactoryService

Parameters:

filterSpec - is the filter definition

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