Examples of com.espertech.esper.view.View

com.espertech.esper.view.View
The View interface provides a way for a stream, data provider, or another view, to notify an object of additions and deletions to its data set. Views are themselves Viewable by other Views, and can implement their own set of cached data internally. The contract is that a View is wholly derived from the object (its parent) to which it is attached. That is, it must be able to reconstitute its cached state from a playback of source data passed to it through the update() method. A view's job is to derive some data from the data in the Viewable object to which it is attached. This can happen by a 'push' mechanism whereby new data in the underlying collection is pushed to the view through the update method. A view that operates in this mode incrementally updates its derived data and then provides this data to any queries or requesters through its Data interface and potentially through other customized methods it exposes. When these methods are called, the view in push mode does not contact its parent: it just supplies the requester with the data it already derived. The push mode is efficient when data in a view is slow-changing with respect to how much its data is requested. For example, a view calculating the mean of an intermittent signal over time may be queried very frequently. It incrementally updates its statistic and then provides that quantity to callers whenever they want it, which may be much more frequently than the incoming signal occurs. The 'pull' mechanism is driven by requests to the view's Data interface or other customized data access methods. A view operating in 'pull' mode may know whether it is "clean" or "dirty" by listening to its update method, or it may not get any calls to its update method, and have to consult its parent to re-derive data when it is called. This mode is efficient when requests to a view for its data are infrequent compared to the update frequency of its parent's data. For example, a temperature sensor may be changing on a near-continuous basis, and a view which derives some quantity from that sensor may be queried irregularly. It is most efficient for that view to operate in pull mode, and only update itself when it is asked by some consumer for its derived quantity. It then asks the temperature sensor for the current temperature, does its derivation, and returns to the requester. To feed views that are registered with it, a view should only call the update method on its child views when its own data has changed. If it receives an update which results in no change to its data, it should not update any children views.

            isHasRemovestreamData = false;  // changed by observer logic to indicate new data
            isRetainObserverEvents = true;  // enable retain logic in observer
            try
            {
                for (int viewIndex = 0; viewIndex < views.length; viewIndex++) {
                    View view = views[viewIndex];
                    view.update(newData, oldData);


                    // first-X asymetric view post no insert stream for events that get dropped, remove these
                    if (newDataChildView != null) {
                        for (int i = 0; i < newData.length; i++) {
                            boolean found = false;
                            for (int j = 0; j < newDataChildView.length; j++) {
                                if (newDataChildView[i] == newData[i]) {
                                    found = true;
                                    break;
                                }
                            }
                            if (!found) {
                                removedByView[i][viewIndex] = true;
                            }
                        }
                    }
                    else {
                        for (int i = 0; i < newData.length; i++) {
                            removedByView[i][viewIndex] = true;
                        }
                    }
                }
            }
            finally
            {
                isRetainObserverEvents = false;                
            }


            // determine removed events, those that have a "true" in the remove by view index for all views
            removalEvents.clear();
            for (int i = 0; i < newData.length; i++) {
                boolean allTrue = true;
                for (int j = 0; j < views.length; j++) {
                    if (!removedByView[i][j]) {
                        allTrue = false;
                        break;
                    }
                }
                if (allTrue) {
                    removalEvents.add(newData[i]);
                    unionWindow.removeAll(newData[i]);
                }
            }


            // remove if any
            if (!removalEvents.isEmpty()) {
                isDiscardObserverEvents = true;
                EventBean[] viewOldData = removalEvents.toArray(new EventBean[removalEvents.size()]);
                try
                {
                    for (int j = 0; j < views.length; j++)
                    {
                        views[j].update(null, viewOldData);
                    }
                }
                finally
                {
                    isDiscardObserverEvents = false;
                }
            }


            // see if any child view has removed any events.
            // if there was an insert stream, handle pushed-out events
            if (isHasRemovestreamData)
            {
                List<EventBean> removedEvents = null;


                // process each buffer
                for (int i = 0; i < oldEventsPerView.length; i++)
                {
                    if (oldEventsPerView[i] == null)
                    {
                        continue;
                    }


                    EventBean[] viewOldData = oldEventsPerView[i];
                    oldEventsPerView[i]= null;  // clear entry


                    // remove events for union, if the last event was removed then add it
                    for (EventBean old : viewOldData)
                    {
                        boolean isNoMoreRef = unionWindow.remove(old);
                        if (isNoMoreRef)
                        {
                            if (removedEvents == null)
                            {
                                removalEvents.clear();
                                removedEvents = removalEvents;
                            }
                            removedEvents.add(old);
                        }
                    }
                }


                if (removedEvents != null)
                {
                    oldData = removedEvents.toArray(new EventBean[removedEvents.size()]);
                }
            }


            newEvents.clear();
            for (int i = 0; i < newData.length; i++) {
                if (!removalEvents.contains(newData[i])) {
                    newEvents.add(newData[i]);
                }
            }


            EventBean[] newDataPosted = null;
            if (!newEvents.isEmpty()) {
                newDataPosted = newEvents.toArray(new EventBean[newEvents.size()]);
            }


            // indicate new and, possibly, old data
            if ((newDataPosted != null) || (oldData != null)) {
                updateChildren(newDataPosted, oldData);
            }
        }


        // handle remove stream
        else if (oldData != null)
        {
            isDiscardObserverEvents = true;    // disable reaction logic in observer


            try
            {
                for (View view : views)
                {
                    view.update(null, oldData);
                }
            }
            finally
            {
                isDiscardObserverEvents = false;

View Full Code Here

                throw new EPException("Unexpected error copying subview " + originalChildView.getClass().getName());
            }
            CloneableView cloneableView = (CloneableView) originalChildView;


            // Copy child node
            View copyChildView = cloneableView.cloneView();
            copyChildView.setParent(groupView);
            subViewList.add(copyChildView);


            // Make the sub views for child copying from the original to the child
            copySubViews(groupView.getCriteriaExpressions(), propertyNames, groupByValues, originalChildView, copyChildView,
                    agentInstanceContext);

View Full Code Here

            if (!(subView instanceof CloneableView))
            {
                throw new EPException("Unexpected error copying subview");
            }
            CloneableView cloneableView = (CloneableView) subView;
            View copiedChild = cloneableView.cloneView();
            copyView.addView(copiedChild);


            // Make the sub views for child
            copySubViews(criteriaExpressions, propertyNames, groupByValues, subView, copiedChild, agentInstanceContext);
        }

View Full Code Here

        else {
            // For each child node
            ArrayList<View> subViewList = new ArrayList<View>(4);
            subviewHolder = subViewList;
            for (View originalChildView : groupView.getViews()) {
                View copyChildView = copyChildView(groupView, propertyNames, groupByValues, agentInstanceContext, originalChildView);
                subViewList.add(copyChildView);
            }
        }


        return subviewHolder;

View Full Code Here

            throw new EPException("Unexpected error copying subview " + originalChildView.getClass().getName());
        }
        CloneableView cloneableView = (CloneableView) originalChildView;


        // Copy child node
        View copyChildView = cloneableView.cloneView();
        copyChildView.setParent(groupView);


        // Make the sub views for child copying from the original to the child
        copySubViews(groupView.getCriteriaExpressions(), propertyNames, groupByValues, originalChildView, copyChildView,
                agentInstanceContext);

View Full Code Here

            if (!(subView instanceof CloneableView))
            {
                throw new EPException("Unexpected error copying subview");
            }
            CloneableView cloneableView = (CloneableView) subView;
            View copiedChild = cloneableView.cloneView();
            copyView.addView(copiedChild);


            // Make the sub views for child
            copySubViews(criteriaExpressions, propertyNames, groupByValues, subView, copiedChild, agentInstanceContext);
        }

View Full Code Here

            isHasRemovestreamData = false;  // changed by observer logic to indicate new data
            isRetainObserverEvents = true;  // enable retain logic in observer
            try
            {
                for (int viewIndex = 0; viewIndex < views.length; viewIndex++) {
                    View view = views[viewIndex];
                    view.update(newData, null);


                    // first-X asymetric view post no insert stream for events that get dropped, remove these
                    if (newDataChildView != null) {
                        for (int i = 0; i < newData.length; i++) {
                            boolean found = false;

View Full Code Here

                throw new EPException("Unexpected error copying subview " + originalChildView.getClass().getName());
            }
            CloneableView cloneableView = (CloneableView) originalChildView;


            // Copy child node
            View copyChildView = cloneableView.cloneView();
            copyChildView.setParent(groupView);
            subViewList.add(copyChildView);


            // Make the sub views for child copying from the original to the child
            copySubViews(groupView.getCriteriaExpressions(), propertyNames, groupByValues, originalChildView, copyChildView,
                    agentInstanceContext);

View Full Code Here

            if (!(subView instanceof CloneableView))
            {
                throw new EPException("Unexpected error copying subview");
            }
            CloneableView cloneableView = (CloneableView) subView;
            View copiedChild = cloneableView.cloneView();
            copyView.addView(copiedChild);


            // Make the sub views for child
            copySubViews(criteriaExpressions, propertyNames, groupByValues, subView, copiedChild, agentInstanceContext);
        }

View Full Code Here

            isHasRemovestreamData = false;  // changed by observer logic to indicate new data
            isRetainObserverEvents = true;  // enable retain logic in observer
            try
            {
                for (int viewIndex = 0; viewIndex < views.length; viewIndex++) {
                    View view = views[viewIndex];
                    view.update(newData, oldData);


                    // first-X asymetric view post no insert stream for events that get dropped, remove these
                    if (newDataChildView != null) {
                        for (int i = 0; i < newData.length; i++) {
                            boolean found = false;
                            for (int j = 0; j < newDataChildView.length; j++) {
                                if (newDataChildView[i] == newData[i]) {
                                    found = true;
                                    break;
                                }
                            }
                            if (!found) {
                                removedByView[i][viewIndex] = true;
                            }
                        }
                    }
                    else {
                        for (int i = 0; i < newData.length; i++) {
                            removedByView[i][viewIndex] = true;
                        }
                    }
                }
            }
            finally
            {
                isRetainObserverEvents = false;                
            }


            // determine removed events, those that have a "true" in the remove by view index for all views
            removalEvents.clear();
            for (int i = 0; i < newData.length; i++) {
                boolean allTrue = true;
                for (int j = 0; j < views.length; j++) {
                    if (!removedByView[i][j]) {
                        allTrue = false;
                        break;
                    }
                }
                if (allTrue) {
                    removalEvents.add(newData[i]);
                    unionWindow.removeAll(newData[i]);
                }
            }


            // remove if any
            if (!removalEvents.isEmpty()) {
                isDiscardObserverEvents = true;
                EventBean[] viewOldData = removalEvents.toArray(new EventBean[removalEvents.size()]);
                try
                {
                    for (int j = 0; j < views.length; j++)
                    {
                        views[j].update(null, viewOldData);
                    }
                }
                finally
                {
                    isDiscardObserverEvents = false;
                }
            }


            // see if any child view has removed any events.
            // if there was an insert stream, handle pushed-out events
            if (isHasRemovestreamData)
            {
                List<EventBean> removedEvents = null;


                // process each buffer
                for (int i = 0; i < oldEventsPerView.length; i++)
                {
                    if (oldEventsPerView[i] == null)
                    {
                        continue;
                    }


                    EventBean[] viewOldData = oldEventsPerView[i];
                    oldEventsPerView[i]= null;  // clear entry


                    // remove events for union, if the last event was removed then add it
                    for (EventBean old : viewOldData)
                    {
                        boolean isNoMoreRef = unionWindow.remove(old);
                        if (isNoMoreRef)
                        {
                            if (removedEvents == null)
                            {
                                removalEvents.clear();
                                removedEvents = removalEvents;
                            }
                            removedEvents.add(old);
                        }
                    }
                }


                if (removedEvents != null)
                {
                    oldData = removedEvents.toArray(new EventBean[removedEvents.size()]);
                }
            }


            newEvents.clear();
            for (int i = 0; i < newData.length; i++) {
                if (!removalEvents.contains(newData[i])) {
                    newEvents.add(newData[i]);
                }
            }


            EventBean[] newDataPosted = null;
            if (!newEvents.isEmpty()) {
                newDataPosted = newEvents.toArray(new EventBean[newEvents.size()]);
            }


            // indicate new and, possibly, old data
            if ((newDataPosted != null) || (oldData != null)) {
                updateChildren(newDataPosted, oldData);
            }
        }


        // handle remove stream
        else if (oldData != null)
        {
            isDiscardObserverEvents = true;    // disable reaction logic in observer


            try
            {
                for (View view : views)
                {
                    view.update(null, oldData);
                }
            }
            finally
            {
                isDiscardObserverEvents = false;

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