/**************************************************************************************
* Copyright (C) 2008 EsperTech, Inc. All rights reserved. *
* http://esper.codehaus.org *
* 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.client.EventBean;
import com.espertech.esper.client.EventType;
import com.espertech.esper.collection.Pair;
import com.espertech.esper.collection.RefCountedMap;
import com.espertech.esper.core.context.util.EPStatementAgentInstanceHandle;
import com.espertech.esper.core.service.EPStatementHandleCallback;
import com.espertech.esper.core.service.StatementAgentInstanceLock;
import com.espertech.esper.epl.expression.ExprEvaluatorContext;
import com.espertech.esper.filter.FilterHandleCallback;
import com.espertech.esper.filter.FilterService;
import com.espertech.esper.filter.FilterSpecCompiled;
import com.espertech.esper.filter.FilterValueSet;
import com.espertech.esper.metrics.instrumentation.InstrumentationHelper;
import com.espertech.esper.view.EventStream;
import com.espertech.esper.view.ZeroDepthStream;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.lang.annotation.Annotation;
import java.util.Collection;
import java.util.IdentityHashMap;
/**
* Service implementation to reuse or not reuse event streams and existing filters depending on
* the type of statement.
* <p>
* 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.
* <p>
* For join statements, always creating a new event stream and
* therefore not reusing view resources, for use with joins.
* <p>
* 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.
* <p>
* 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
*/
public class StreamFactorySvcImpl implements StreamFactoryService
{
private static Log log = LogFactory.getLog(StreamFactorySvcImpl.class);
// Using identify hash map - ignoring the equals semantics on filter specs
// Thus two filter specs objects are always separate entries in the map
private final IdentityHashMap<Object, Pair<EventStream, EPStatementHandleCallback>> eventStreamsIdentity;
// Using a reference-counted map for non-join statements
private final RefCountedMap<FilterSpecCompiled, Pair<EventStream, EPStatementHandleCallback>> eventStreamsRefCounted;
private final String engineURI;
private final boolean isReuseViews;
/**
* Ctor.
* @param isReuseViews indicator on whether stream and view resources are to be reused between statements
*/
public StreamFactorySvcImpl(String engineURI, boolean isReuseViews)
{
this.engineURI = engineURI;
this.eventStreamsRefCounted = new RefCountedMap<FilterSpecCompiled, Pair<EventStream, EPStatementHandleCallback>>();
this.eventStreamsIdentity = new IdentityHashMap<Object, Pair<EventStream, EPStatementHandleCallback>>();
this.isReuseViews = isReuseViews;
}
public void destroy()
{
eventStreamsRefCounted.clear();
eventStreamsIdentity.clear();
}
/**
* See the method of the same name in {@link com.espertech.esper.view.stream.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.
*
* @param filterSpec is the filter definition
* @param epStatementAgentInstanceHandle is the statement resource lock
* @return newly createdStatement event stream, not reusing existing instances
*/
public Pair<EventStream, StatementAgentInstanceLock> createStream(final String statementId,
final FilterSpecCompiled filterSpec,
FilterService filterService,
EPStatementAgentInstanceHandle epStatementAgentInstanceHandle,
boolean isJoin,
final ExprEvaluatorContext exprEvaluatorContext,
final boolean hasOrderBy,
boolean filterWithSameTypeSubselect,
Annotation[] annotations,
boolean stateless,
final int streamNum
)
{
if (log.isDebugEnabled())
{
log.debug(".createStream hashCode=" + filterSpec.hashCode() + " filter=" + filterSpec);
}
// Check if a stream for this filter already exists
Pair<EventStream, EPStatementHandleCallback> pair;
boolean forceNewStream = isJoin || (!isReuseViews) || hasOrderBy || filterWithSameTypeSubselect || stateless;
if (forceNewStream)
{
pair = eventStreamsIdentity.get(filterSpec);
}
else
{
pair = eventStreamsRefCounted.get(filterSpec);
}
// If pair exists, either reference count or illegal state
if (pair != null)
{
if (forceNewStream)
{
throw new IllegalStateException("Filter spec object already found in collection");
}
else
{
log.debug(".createStream filter already found");
eventStreamsRefCounted.reference(filterSpec);
// audit proxy
EventStream eventStream = EventStreamProxy.getAuditProxy(engineURI, epStatementAgentInstanceHandle.getStatementHandle().getStatementName(), annotations, filterSpec, pair.getFirst());
// We return the lock of the statement first establishing the stream to use that as the new statement's lock
return new Pair<EventStream, StatementAgentInstanceLock>(eventStream, pair.getSecond().getAgentInstanceHandle().getStatementAgentInstanceLock());
}
}
// New event stream
EventType resultEventType = filterSpec.getResultEventType();
EventStream zeroDepthStream = new ZeroDepthStream(resultEventType);
// audit proxy
EventStream inputStream = EventStreamProxy.getAuditProxy(engineURI, epStatementAgentInstanceHandle.getStatementHandle().getStatementName(), annotations, filterSpec, zeroDepthStream);
final EventStream eventStream = inputStream;
FilterHandleCallback filterCallback;
if (filterSpec.getOptionalPropertyEvaluator() != null)
{
filterCallback = new FilterHandleCallback()
{
public String getStatementId()
{
return statementId;
}
public void matchFound(EventBean theEvent, Collection<FilterHandleCallback> allStmtMatches)
{
EventBean[] result = filterSpec.getOptionalPropertyEvaluator().getProperty(theEvent, exprEvaluatorContext);
if (result == null)
{
return;
}
eventStream.insert(result);
}
public boolean isSubSelect()
{
return false;
}
};
}
else
{
filterCallback = new FilterHandleCallback()
{
public String getStatementId()
{
return statementId;
}
public void matchFound(EventBean theEvent, Collection<FilterHandleCallback> allStmtMatches)
{
InstrumentationHelper.get().qFilterActivationStream(theEvent.getEventType().getName(), streamNum);
eventStream.insert(theEvent);
InstrumentationHelper.get().aFilterActivationStream();
}
public boolean isSubSelect()
{
return false;
}
};
}
EPStatementHandleCallback handle = new EPStatementHandleCallback(epStatementAgentInstanceHandle, filterCallback);
// Store stream for reuse
pair = new Pair<EventStream, EPStatementHandleCallback>(eventStream, handle);
if (forceNewStream)
{
eventStreamsIdentity.put(filterSpec, pair);
}
else
{
eventStreamsRefCounted.put(filterSpec, pair);
}
// Activate filter
FilterValueSet filterValues = filterSpec.getValueSet(null, exprEvaluatorContext, null);
filterService.add(filterValues, handle);
return new Pair<EventStream, StatementAgentInstanceLock>(inputStream, null);
}
/**
* See the method of the same name in {@link com.espertech.esper.view.stream.StreamFactoryService}.
* @param filterSpec is the filter definition
*/
public void dropStream(FilterSpecCompiled filterSpec, FilterService filterService, boolean isJoin, boolean hasOrderBy, boolean filterWithSameTypeSubselect, boolean stateless)
{
Pair<EventStream, EPStatementHandleCallback> pair;
boolean forceNewStream = isJoin || (!isReuseViews) || hasOrderBy || filterWithSameTypeSubselect || stateless;
if (forceNewStream)
{
pair = eventStreamsIdentity.get(filterSpec);
if (pair == null)
{
throw new IllegalStateException("Filter spec object not in collection");
}
eventStreamsIdentity.remove(filterSpec);
filterService.remove(pair.getSecond());
}
else
{
pair = eventStreamsRefCounted.get(filterSpec);
boolean isLast = eventStreamsRefCounted.dereference(filterSpec);
if (isLast)
{
filterService.remove(pair.getSecond());
}
}
}
}