Application: gvSIG desktop

/**

 * gvSIG. Desktop Geographic Information System.

 *

 * Copyright (C) 2007-2013 gvSIG Association.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 3

 * of the License, or (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,

 * MA  02110-1301, USA.

 *

 * For any additional information, do not hesitate to contact us

 * at info AT gvsig.com, or visit our website www.gvsig.com.

 */

package org.gvsig.fmap.dal.feature.paging.impl;

import java.util.ArrayList;

import java.util.Collection;

import java.util.Date;

import java.util.Iterator;

import java.util.List;

import java.util.ListIterator;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.gvsig.fmap.dal.exception.DataException;

import org.gvsig.fmap.dal.feature.EditableFeature;

import org.gvsig.fmap.dal.feature.Feature;

import org.gvsig.fmap.dal.feature.FeatureQuery;

import org.gvsig.fmap.dal.feature.FeatureSelection;

import org.gvsig.fmap.dal.feature.FeatureSet;

import org.gvsig.fmap.dal.feature.FeatureStore;

import org.gvsig.fmap.dal.feature.FeatureType;

import org.gvsig.fmap.dal.feature.exception.ConcurrentDataModificationException;

import org.gvsig.fmap.dal.feature.exception.FeatureIndexException;

import org.gvsig.fmap.dal.feature.impl.dynobjectutils.DynObjectFeatureFacade;

import org.gvsig.fmap.dal.feature.paging.FacadeOfAFeaturePagingHelper;

import org.gvsig.fmap.dal.feature.paging.FeaturePagingHelper;

import org.gvsig.tools.dynobject.DynObject;

import org.gvsig.tools.dynobject.DynObjectSet;

import org.gvsig.tools.dynobject.impl.DefaultDynObjectPagingHelper;

import org.gvsig.tools.exception.BaseException;

import org.gvsig.tools.visitor.VisitCanceledException;

import org.gvsig.tools.visitor.Visitor;

/**

 * Helper class to access the values of a FeatureCollection by position. Handles

 * pagination automatically to avoid filling the memory in case of big

 * collections.

 *

 * TODO: evaluate if its more convenient to read values in the background when

 * the returned value is near the end of the page, instead of loading a page on

 * demand.

 *

 * @author gvSIG Team

 */

public class FeaturePagingHelperImpl extends DefaultDynObjectPagingHelper

    implements FeaturePagingHelper {

    private static final Logger LOG = LoggerFactory.getLogger(FeaturePagingHelperImpl.class);

    private static class Page {

        private Feature[] features;

        private final long number;

        private final int size;

        private long lastaccess;

        public Page(long number, int size) {

            this.size = size;

            this.number = number;

            this.features = new Feature[size];

            this.lastaccess = 0;

        }

        public void setFeature(int i, Feature copy) {

            this.features[i] = copy;

        }

        public Feature[] getFeatures() {

            this.lastaccess = (new Date()).getTime();

            return this.features;

        }

        public long getPageNumber() {

            return this.number;

        }

        public long getLastAccess() {

            return this.lastaccess;

        }

        public int size() {

            return this.size;

        }

        public void dispose() {

            for (int i = 0; i < features.length; i++) {

                features[i] = null;

            }

            this.features = null;

            this.lastaccess = 0;

        }

    } 

    private static class PageCache {

        private final int maxpages;

        private List<Page> pages;

        public PageCache(int maxpages) {

            this.maxpages = maxpages;

            this.pages = new ArrayList<>();

        }

        public void clear() {

            for (Page page : pages) {

                page.dispose();

            }

            this.pages = new ArrayList<>();    

        }

        public Page get(long pageNumber) {

            for( Page page : pages ) {

                if( page.getPageNumber() == pageNumber ) {

                    return page;

                }

            }

            return null;

        }

        public void add(Page page) {

            if( this.pages.size()< this.maxpages ) {

                this.pages.add(page);

                return;

            }

            int toDrop = 0;

            for( int i=0; i<this.pages.size(); i++ ) {

                if( this.pages.get(i).getLastAccess()<this.pages.get(toDrop).getLastAccess() ) {

                    toDrop = i;

                }

            }

            this.pages.set(toDrop, page);

        }

    }

    private FeatureQuery query;

    private FeatureStore featureStore;

    /** If the selected Features must be returned as the first ones. **/

    private boolean selectionUp = false;

    private FeatureSet featSet = null;

    private FeatureSelection initialSelection = null;

    private Feature[] features = null;

    private PageCache cachedPages = null;

    private boolean initialization_completed = false;

    private FeatureSelection selection = null;

    /**

     * Constructs a FeaturePagingHelperImpl from data of a FeatureStore.

     *

     * @param featureStore

     *            to extract data from

     * @throws DataException

     *             if there is an error initializing the helper

     */

    public FeaturePagingHelperImpl(FeatureStore featureStore)

        throws BaseException {

        this(featureStore, DEFAULT_PAGE_SIZE);

    }

    /**

     * Constructs a FeaturePagingHelperImpl from data of a FeatureStore.

     *

     * @param featureStore

     *            to extract data from

     * @param pageSize

     *            the number of elements per page data

     * @throws DataException

     *             if there is an error initializing the helper

     */

    public FeaturePagingHelperImpl(FeatureStore featureStore, int pageSize)

        throws BaseException {

        this(featureStore, null, pageSize);

    }

    /**

     * Constructs a FeaturePagingHelperImpl from data of a FeatureStore.

     *

     * @param featureStore

     *            to extract data from

     * @throws DataException

     *             if there is an error initializing the helper

     */

    public FeaturePagingHelperImpl(FeatureStore featureStore,

        FeatureQuery featureQuery) throws BaseException {

        this(featureStore, featureQuery, DEFAULT_PAGE_SIZE);

    }

    /**

     * Constructs a FeaturePagingHelperImpl from data of a FeatureStore.

     *

     * @param featureSet

     *            to extract data from

     * @param pageSize

     *            the number of elements per page data

     * @throws DataException

     *             if there is an error initializing the helper

     */

    public FeaturePagingHelperImpl(FeatureStore featureStore,

        FeatureQuery featureQuery, int pageSize) throws BaseException {

        super();

        this.cachedPages = new PageCache(3);

        FeatureQuery query = featureQuery;

        if (featureQuery == null) {

            query = featureStore.createFeatureQuery();

            query.setFeatureType(featureStore.getDefaultFeatureType());

        }

        this.featureStore = featureStore;

        this.query = query;

        this.query.setPageSize(pageSize);

        setDefaultCalculator(new Sizeable() {

            public long getSize() {

                    FeatureSet featureSet = getFeatureSet(false);

                try {

                                        return featureSet.getSize();

                } catch (BaseException e) {

                    LOG.error("Error getting the size of the FeatureSet: "

                        + featureSet, e);

                    return 0l;

                }

            }

        }, pageSize);

        if (LOG.isDebugEnabled()) {

            LOG.debug("FeaturePagingHelperImpl created with {} pages, "

                + "and a page size of {}", new Long(getCalculator()

                .getNumPages()), new Integer(pageSize));

        }

        this.initialization_completed = true;

    }

    /**

     * @return the selectionUp status

     */

    public boolean isSelectionUp() {

        return selectionUp;

    }

    public FeatureSelection getSelection() {

        if (selection == null) {

            try {

                return getFeatureStore().getFeatureSelection();

            } catch (Exception e) {

                LOG.warn("Error getting the selection", e);

            }

        }

        return selection;

    }

    public void setSelection(FeatureSelection selection) {

        this.selection = selection;

    }

    @Override

    public void setSelectionUp(boolean selectionUp) {

        this.selectionUp = selectionUp;

        try {

            FeatureSelection currentSelection = getSelection();

            if (selectionUp && !currentSelection.isEmpty()) {

                initialSelection =(FeatureSelection) currentSelection.clone();

                setCalculator(new OneSubsetOneSetPagingCalculator(

                    new FeatureSetSizeableDelegate(initialSelection),

                    new FeatureSetSizeableDelegate(getFeatureSet(false)),

                    getMaxPageSize()));

            } else {

                if (initialSelection != null) {

                    initialSelection.dispose();

                    initialSelection = null;

                }

                setDefaultCalculator(new FeatureSetSizeableDelegate(

                    getFeatureSet(false)), getMaxPageSize());

            }

        } catch (BaseException e) {

            LOG.error("Error setting the selection up setting to: "

                + selectionUp, e);

        } catch (CloneNotSupportedException e) {

            LOG.error("Error cloning the selection "

                + "while setting the selection up", e);

        }

    }

    public synchronized Feature getFeatureAt(long index) throws BaseException {

        // Check if we have currently loaded the viewed page data,

        // or we need to load a new one

            int maxPageSize = getMaxPageSize();

            long currentPage = getCurrentPage();

            long currentPage2 = currentPage;

        long pageForIndex = (long) Math.floor(index / maxPageSize);

        if (pageForIndex != currentPage) {

            setCurrentPage(pageForIndex);

            currentPage2 = getCurrentPage();

        }

        long positionForIndex = index - (currentPage2 * maxPageSize);

        if (positionForIndex >= getCurrentPageFeatures().length) {

            throw new FeatureIndexException(

                new IndexOutOfBoundsException("positionForIndex too big: "

                    + positionForIndex));

        } else {

            Feature feature = getCurrentPageFeatures()[(int) positionForIndex];

            return feature;

        }

    }

    public Feature[] getCurrentPageFeatures() {

        if( this.features==null ) {

            try {

                this.loadCurrentPageData();

            } catch (BaseException ex) {

                // Do nothing

            }

            if( this.features == null ) {

                String msg = "Can't retrieve the features from current page.";

                LOG.warn(msg);

                throw new RuntimeException(msg);

            }

        }

        return features;

    }

    /**

     * Gets the feature set.

     * The boolean tells whether we must create the featureset

     * again (for example perhaps we need it after a feature

     * has been added/removed)

     */

    private FeatureSet getFeatureSet(boolean reset) {

        if (featSet == null || reset) {

            if (featSet != null) {

                try {

                    featSet.dispose();

                } catch (Exception ex) {

                    LOG.info("Error while disposing featset.", ex);

                }

            }

            try {

                FeatureStore featureStore = getFeatureStore();

                synchronized (featureStore) {

                    featSet = featureStore.getFeatureSet(getFeatureQuery());

                }

            } catch (DataException e) {

                throw new RuntimeException("Error getting a feature set with the query " + getFeatureQuery());

            }

        }

        return featSet;

    }

    @Override

    public DynObjectSet getDynObjectSet() {

            return getFeatureSet(false).getDynObjectSet();

    }

    @Override

    public void reloadCurrentPage() throws BaseException {

        boolean sel_up = this.isSelectionUp();

        setSelectionUp(false);

        if (getCalculator().getCurrentPage() > -1) {

            this.cachedPages.clear();

            loadCurrentPageData();

        }

        if (sel_up) {

            setSelectionUp(true);

        }

    }

    @Override

    public void reload() throws BaseException {

        this.cachedPages.clear();

        /*

         * Force re-creation of feature set

         */

        this.getFeatureSet(true);

        setDefaultCalculator(new Sizeable() {

            public long getSize() {

                    FeatureSet featureSet = getFeatureSet(false);

                try {

                                        return featureSet.getSize();

                } catch (BaseException e) {

                    LOG.error("Error getting the size of the FeatureSet: "

                        + featureSet, e);

                    return 0l;

                }

            }

        }, getCalculator().getMaxPageSize());

        reloadCurrentPage();

    }

    public FeatureStore getFeatureStore() {

        return featureStore;

    }

    public FeatureQuery getFeatureQuery() {

        return query;

    }

    /**

     * Loads all the Features of the current page.

     * @throws org.gvsig.tools.exception.BaseException

     */

    @Override

    protected synchronized void loadCurrentPageData() throws BaseException {

        if( !initialization_completed ) {

            return;

        }

        final int currentPageSize = getCalculator().getCurrentPageSize();

        final long currentPage = getCalculator().getCurrentPage();

        Page page = this.cachedPages.get(currentPage);

        if( page==null ) {

            page = new Page(currentPage, currentPageSize);

            long t1 = 0;

            if (LOG.isTraceEnabled()) {

                t1 = System.currentTimeMillis();

            }

            if (selectionUp) {

                loadCurrentPageDataWithSelectionUp(page);

            } else {

                loadCurrentPageDataNoSelection(page);

            }

            if (LOG.isTraceEnabled()) {

                long t2 = System.currentTimeMillis();

                LOG.trace("Time to load {} features: {} ms", currentPageSize, t2 - t1);

            }

            this.cachedPages.add(page);

        }

        this.features = page.getFeatures();

    }

    private void loadCurrentPageDataWithSelectionUp(final Page page)

            throws BaseException {

        FeatureSelection selection = initialSelection;

        if (selection == null) {

            loadCurrentPageDataNoSelection(page);

        } else {

            FeatureSet set = getFeatureSet(false);

            try {

                OneSubsetOneSetPagingCalculator twoSetsCalculator = null;

                if (getCalculator() instanceof OneSubsetOneSetPagingCalculator) {

                    twoSetsCalculator

                            = (OneSubsetOneSetPagingCalculator) getCalculator();

                } else {

                    twoSetsCalculator

                            = new OneSubsetOneSetPagingCalculator(

                                    new FeatureSetSizeableDelegate(selection),

                                    new FeatureSetSizeableDelegate(set),

                                    getMaxPageSize(), getCalculator().getCurrentPage());

                    setCalculator(twoSetsCalculator);

                }

                // First load values from the selection, if the current page has

                // elements from it

                if (twoSetsCalculator.hasCurrentPageAnyValuesInFirstSet()) {

                    loadDataFromFeatureSet(page, 0, selection,

                            twoSetsCalculator.getFirstSetInitialIndex(),

                            twoSetsCalculator.getFirstSetHowMany(), null);

                }

                // Next, load values from the FeatureSet if the current page has values

                // from it

                if (twoSetsCalculator.hasCurrentPageAnyValuesInSecondSet()) {

                    loadDataFromFeatureSet(

                            page,

                            // The cast will work as that size will be <= maxpagesize,

                            // which is an int

                            (int) twoSetsCalculator.getFirstSetHowMany(), set,

                            twoSetsCalculator.getSecondSetInitialIndex(),

                            twoSetsCalculator.getSecondSetHowMany(), selection);

                }

            } finally {

                /*

                 * This is the feature set

                 * we dont want to lose it

                 */

                // set.dispose();

            }

        }

    }

    private void loadCurrentPageDataNoSelection(final Page page)

        throws BaseException {

        long firstPosition = getCalculator().getInitialIndex();

        if (LOG.isDebugEnabled()) {

            LOG.debug("Loading {} Features starting at position {}", 

                getCalculator().getCurrentPageSize(), firstPosition

            );

        }

        FeatureSet featureSet = getFeatureSet(false);

        try {

                loadDataFromFeatureSet(page, 0, featureSet, firstPosition,

                                getCalculator().getCurrentPageSize(), null);

        } catch(DataException ex) {

            throw ex;

            // } finally {

                // featureSet.dispose();

        }

    }

    private void loadDataFromFeatureSet(final Page page,

        final int valuesPosition, FeatureSet set, long initialIndex,

        final long howMany, final FeatureSelection selectedFeaturesToSkip)

        throws DataException {

        try {

            set.accept(new Visitor() {

                private int i = valuesPosition;

                @Override

                public void visit(Object obj) throws VisitCanceledException,

                    BaseException {

                    if (i >= valuesPosition + howMany) {

                        throw new VisitCanceledException();

                    }

                    Feature current = (Feature) obj;

                    // Add the current Feature only if we don't skip selected

                    // features or the feature is not selected

                    if (selectedFeaturesToSkip == null

                        || !selectedFeaturesToSkip.isSelected(current)) {

                        try {

                            page.setFeature(i,current.getCopy());

                            i++;

                        } catch(Exception ex) {

                            // Aqui no deberia petar, pero...

                            // me he encontrado un caso que tenia una referencia a

                            // una feature seleccionada que ya no existia. No se como

                            // habia pasado, se habia quedado de antes guardada en el

                            // proyecto pero la feature ya no existia, y eso hacia que

                            // petase al intentar leer de disco la feature a partir

                            // de una referencia no valida.

                        }

                    }

                }

            }, initialIndex, howMany);

        } catch(VisitCanceledException ex) {

            // Do nothing

        } catch (BaseException e) {

            if (e instanceof DataException) {

                throw ((DataException) e);

            } else {

                LOG.error("Error loading the data starting at position {}",

                    new Long(initialIndex), e);

            }

        }

    }

    public void delete(Feature feature) throws BaseException {

        featureStore.delete(feature);

        /*

         * Force re-creation of feature set

         */

        this.getFeatureSet(true);

        reloadCurrentPage();

    }

    public void insert(EditableFeature feature) throws BaseException {

            featureStore.insert(feature);

        /*

         * Force re-creation of feature set

         */

        this.getFeatureSet(true);

        reloadCurrentPage();

    }

    public void update(EditableFeature feature) throws BaseException {

            featureStore.update(feature);

        /*

         * Force re-creation of feature set

         */

        this.getFeatureSet(true);

        reloadCurrentPage();

    }

    public FeatureType getFeatureType() {

        FeatureType ft = null;

        try {

            ft = featureStore.getDefaultFeatureType();

        } catch (DataException e) {

            LOG.error("Error while getting feature type: " +

                e.getMessage(), e);

        }

        return ft;

        /*

         *

        FeatureSet featureSet = getFeatureSet();

        try {

            return featureSet.getDefaultFeatureType();

        } finally {

            featureSet.dispose();

        }

        */

    }

    protected void doDispose() throws BaseException {

        initialSelection.dispose();

        if (featSet != null) {

            try {

                featSet.dispose();

            } catch (Exception ex) {

                LOG.info("Error while disposing featset.", ex);

            }

        }

    }

    public DynObject[] getCurrentPageDynObjects() {

        Feature[] features = getCurrentPageFeatures();

        DynObject[] dynobjects = new DynObject[features.length];

        for (int i = 0; i < dynobjects.length; i++) {

            dynobjects[i] = new DynObjectFeatureFacade(features[i]);

        }

        return dynobjects;

    }

    public DynObject getDynObjectAt(long index) throws BaseException {

        return new DynObjectFeatureFacade(getFeatureAt(index));

    }

    public List asList() {

        return new FeaturePagingHelperList();

    }

    public List asListOfDynObjects() {

        return new DynObjectPagingHelperList();

    }

    private class FeaturePagingHelperList extends PagingHelperList {

        public Object get(int i) {

            try {

                return getFeatureAt(i);

            } catch (BaseException ex) {

                throw  new RuntimeException(ex);

            }

        }

    }

    private class DynObjectPagingHelperList extends PagingHelperList {

        public Object get(int i) {

            try {

                return getDynObjectAt(i);

            } catch (BaseException ex) {

                throw  new RuntimeException(ex);

            }

        }

    }

    private abstract class PagingHelperList implements List,  FacadeOfAFeaturePagingHelper {

        @Override

        public FeaturePagingHelper getFeaturePagingHelper() {

            return FeaturePagingHelperImpl.this;

        }

        public int size() {

            try {

                return (int) getFeatureSet(false).getSize();

            } catch (DataException ex) {

                throw  new RuntimeException(ex);

            }

        }

        public boolean isEmpty() {

            try {

                return getFeatureSet(false).isEmpty();

            } catch (DataException ex) {

                throw  new RuntimeException(ex);

            } catch (ConcurrentDataModificationException ex) {

                LOG.warn(

                    "Error to asking about the emptiness of the store. Retrying reloading data.",

                    ex);

                try {

                    reload();

                } catch (BaseException e) {

                    LOG.warn("Error reloading data.", e);

                    throw new RuntimeException(e);

                }

                try {

                    return getFeatureSet(false).isEmpty();

                } catch (DataException e) {

                    LOG.warn(

                        "Error to asking about the emptiness of the store after reloading data.",

                        e);

                    throw new RuntimeException(e);

                }

            }

        }

        public Iterator iterator() {

            try {

                return getFeatureSet(false).fastIterator();

            } catch (DataException ex) {

                throw  new RuntimeException(ex);

            }

        }

        public boolean contains(Object o) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public Object[] toArray() {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public Object[] toArray(Object[] ts) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public boolean add(Object e) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public boolean remove(Object o) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public boolean containsAll(Collection clctn) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public boolean addAll(Collection clctn) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public boolean addAll(int i, Collection clctn) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public boolean removeAll(Collection clctn) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public boolean retainAll(Collection clctn) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public void clear() {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public Object set(int i, Object e) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public void add(int i, Object e) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public Object remove(int i) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public int indexOf(Object o) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public int lastIndexOf(Object o) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public ListIterator listIterator() {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public ListIterator listIterator(int i) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

        public List subList(int i, int i1) {

            throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates.

        }

    }

}