Java tutorial
/************************************************************************************** * 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.std; import com.espertech.esper.client.EventBean; import com.espertech.esper.client.EventType; import com.espertech.esper.collection.MultiKeyUntyped; import com.espertech.esper.collection.Pair; import com.espertech.esper.core.context.util.AgentInstanceViewFactoryChainContext; import com.espertech.esper.epl.expression.ExprEvaluator; import com.espertech.esper.epl.expression.ExprNode; import com.espertech.esper.util.ExecutionPathDebugLog; import com.espertech.esper.view.CloneableView; import com.espertech.esper.view.StoppableView; import com.espertech.esper.view.View; import com.espertech.esper.view.ViewSupport; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import java.util.*; public class GroupByViewReclaimAged extends ViewSupport implements CloneableView, GroupByView { private final ExprNode[] criteriaExpressions; private final ExprEvaluator[] criteriaEvaluators; protected final AgentInstanceViewFactoryChainContext agentInstanceContext; private final long reclaimMaxAge; private final long reclaimFrequency; private EventBean[] eventsPerStream = new EventBean[1]; protected String[] propertyNames; protected final Map<Object, GroupByViewAgedEntry> subViewsPerKey = new HashMap<Object, GroupByViewAgedEntry>(); private final HashMap<GroupByViewAgedEntry, Pair<Object, Object>> groupedEvents = new HashMap<GroupByViewAgedEntry, Pair<Object, Object>>(); private Long nextSweepTime = null; /** * Constructor. * @param agentInstanceContext contains required view services * @param criteriaExpressions is the fields from which to pull the values to group by * @param reclaimMaxAge age after which to reclaim group * @param reclaimFrequency frequency in which to check for groups to reclaim */ public GroupByViewReclaimAged(AgentInstanceViewFactoryChainContext agentInstanceContext, ExprNode[] criteriaExpressions, ExprEvaluator[] criteriaEvaluators, double reclaimMaxAge, double reclaimFrequency) { this.agentInstanceContext = agentInstanceContext; this.criteriaExpressions = criteriaExpressions; this.criteriaEvaluators = criteriaEvaluators; this.reclaimMaxAge = (long) (reclaimMaxAge * 1000d); this.reclaimFrequency = (long) (reclaimFrequency * 1000d); propertyNames = new String[criteriaExpressions.length]; for (int i = 0; i < criteriaExpressions.length; i++) { propertyNames[i] = criteriaExpressions[i].toExpressionString(); } } public View cloneView() { return new GroupByViewReclaimAged(agentInstanceContext, criteriaExpressions, criteriaEvaluators, reclaimMaxAge, reclaimFrequency); } /** * Returns the field name that provides the key valie by which to group by. * @return field name providing group-by key. */ public ExprNode[] getCriteriaExpressions() { return criteriaExpressions; } public final EventType getEventType() { // The schema is the parent view's schema return parent.getEventType(); } public final void update(EventBean[] newData, EventBean[] oldData) { long currentTime = agentInstanceContext.getTimeProvider().getTime(); if ((nextSweepTime == null) || (nextSweepTime <= currentTime)) { if ((ExecutionPathDebugLog.isDebugEnabled) && (log.isDebugEnabled())) { log.debug("Reclaiming groups older then " + reclaimMaxAge + " msec and every " + reclaimFrequency + "msec in frequency"); } nextSweepTime = currentTime + reclaimFrequency; sweep(currentTime); } // Algorithm for single new event if ((newData != null) && (oldData == null) && (newData.length == 1)) { EventBean theEvent = newData[0]; EventBean[] newDataToPost = new EventBean[] { theEvent }; Object groupByValuesKey = getGroupKey(theEvent); // Get child views that belong to this group-by value combination GroupByViewAgedEntry subViews = this.subViewsPerKey.get(groupByValuesKey); // If this is a new group-by value, the list of subviews is null and we need to make clone sub-views if (subViews == null) { Object subviewsList = GroupByViewImpl.makeSubViews(this, propertyNames, groupByValuesKey, agentInstanceContext); subViews = new GroupByViewAgedEntry(subviewsList, currentTime); subViewsPerKey.put(groupByValuesKey, subViews); } else { subViews.setLastUpdateTime(currentTime); } GroupByViewImpl.updateChildViews(subViews.getSubviewHolder(), newDataToPost, null); } else { // Algorithm for dispatching multiple events if (newData != null) { for (EventBean newValue : newData) { handleEvent(newValue, true); } } if (oldData != null) { for (EventBean oldValue : oldData) { handleEvent(oldValue, false); } } // Update child views for (Map.Entry<GroupByViewAgedEntry, Pair<Object, Object>> entry : groupedEvents.entrySet()) { EventBean[] newEvents = GroupByViewImpl.convertToArray(entry.getValue().getFirst()); EventBean[] oldEvents = GroupByViewImpl.convertToArray(entry.getValue().getSecond()); GroupByViewImpl.updateChildViews(entry.getKey(), newEvents, oldEvents); } groupedEvents.clear(); } } private void handleEvent(EventBean theEvent, boolean isNew) { Object groupByValuesKey = getGroupKey(theEvent); // Get child views that belong to this group-by value combination GroupByViewAgedEntry subViews = this.subViewsPerKey.get(groupByValuesKey); // If this is a new group-by value, the list of subviews is null and we need to make clone sub-views if (subViews == null) { Object subviewsList = GroupByViewImpl.makeSubViews(this, propertyNames, groupByValuesKey, agentInstanceContext); long currentTime = agentInstanceContext.getStatementContext().getTimeProvider().getTime(); subViews = new GroupByViewAgedEntry(subviewsList, currentTime); subViewsPerKey.put(groupByValuesKey, subViews); } else { subViews.setLastUpdateTime(agentInstanceContext.getStatementContext().getTimeProvider().getTime()); } // Construct a pair of lists to hold the events for the grouped value if not already there Pair<Object, Object> pair = groupedEvents.get(subViews); if (pair == null) { pair = new Pair<Object, Object>(null, null); groupedEvents.put(subViews, pair); } // Add event to a child view event list for later child update that includes new and old events if (isNew) { pair.setFirst(GroupByViewImpl.addUpgradeToDequeIfPopulated(pair.getFirst(), theEvent)); } else { pair.setSecond(GroupByViewImpl.addUpgradeToDequeIfPopulated(pair.getSecond(), theEvent)); } } public final Iterator<EventBean> iterator() { throw new UnsupportedOperationException("Cannot iterate over group view, this operation is not supported"); } public final String toString() { return this.getClass().getName() + " groupFieldNames=" + Arrays.toString(criteriaExpressions); } private void sweep(long currentTime) { ArrayDeque<Object> removed = new ArrayDeque<Object>(); for (Map.Entry<Object, GroupByViewAgedEntry> entry : subViewsPerKey.entrySet()) { long age = currentTime - entry.getValue().getLastUpdateTime(); if (age > reclaimMaxAge) { removed.add(entry.getKey()); } } for (Object key : removed) { GroupByViewAgedEntry entry = subViewsPerKey.remove(key); Object subviewHolder = entry.getSubviewHolder(); if (subviewHolder instanceof List) { List<View> subviews = (List<View>) subviewHolder; for (View view : subviews) { removeSubview(view); } } else if (subviewHolder instanceof View) { removeSubview((View) subviewHolder); } } } private void removeSubview(View view) { view.setParent(null); recursiveMergeViewRemove(view); if (view instanceof StoppableView) { ((StoppableView) view).stopView(); } } private void recursiveMergeViewRemove(View view) { for (View child : view.getViews()) { if (child instanceof MergeView) { MergeView mergeView = (MergeView) child; mergeView.removeParentView(view); } else { if (child instanceof StoppableView) { ((StoppableView) child).stopView(); } if (child.getViews().length > 0) { recursiveMergeViewRemove(child); } } } } private Object getGroupKey(EventBean theEvent) { eventsPerStream[0] = theEvent; if (criteriaEvaluators.length == 1) { return criteriaEvaluators[0].evaluate(eventsPerStream, true, agentInstanceContext); } Object[] values = new Object[criteriaEvaluators.length]; for (int i = 0; i < criteriaEvaluators.length; i++) { values[i] = criteriaEvaluators[i].evaluate(eventsPerStream, true, agentInstanceContext); } return new MultiKeyUntyped(values); } private static final Log log = LogFactory.getLog(GroupByViewReclaimAged.class); }