LazyChecker.java

/*
 * JBoss, Home of Professional Open Source.
 * Copyright 2012, Red Hat, Inc., and individual contributors
 * as indicated by the @author tags. See the copyright.txt file in the
 * distribution for a full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.jboss.capedwarf.datastore.query;

import java.util.List;
import java.util.concurrent.atomic.AtomicBoolean;

import com.google.appengine.api.datastore.Cursor;
import com.google.appengine.api.datastore.FetchOptions;
import com.google.appengine.api.datastore.Query;
import org.infinispan.query.CacheQuery;
import org.jboss.capedwarf.datastore.LazyKeyChecker;
import org.jboss.capedwarf.shared.compatibility.Compatibility;

/**
 * @author <a href="mailto:ales.justin@jboss.org">Ales Justin</a>
 * @author <a href="mailto:mluksa@redhat.com">Marko Luksa</a>
 */
public class LazyChecker extends LazyKeyChecker {
    private final AtomicBoolean checked = new AtomicBoolean();

    protected final QueryHolder holder;
    protected final FetchOptions fetchOptions;

    public LazyChecker(QueryHolder holder, FetchOptions fetchOptions) {
        super(holder.getQuery().getAncestor(), holder.isInTx());
        this.holder = holder;
        this.fetchOptions = fetchOptions;
    }

    protected LazySize getLazySize() {
        return new LazySize() {
            public int getSize() {
                return holder.getCacheQuery().getResultSize();
            }
        };
    }

    protected void apply() {
        final CacheQuery cacheQuery = holder.getCacheQuery();

        Integer offset = fetchOptions.getOffset();
        Integer cursorOffset = null;
        Cursor startCursor = fetchOptions.getStartCursor();
        if (startCursor != null) {
            cursorOffset = CapedwarfCursorHelper.readIndex(startCursor);
        }
        if (offset != null || cursorOffset != null) {
            offset = (offset == null ? 0 : offset)
                + (cursorOffset == null ? 0 : cursorOffset);
            cacheQuery.firstResult(offset);
        }

        Integer limit = fetchOptions.getLimit();
        Integer cursorLimit = null;
        Cursor endCursor = fetchOptions.getEndCursor();
        if (endCursor != null) {
            int last = CapedwarfCursorHelper.readIndex(endCursor)-1;
            int first = (offset == null) ? 0 : offset;
            cursorLimit = Math.max(0, last - first + 1);
        }
        if (limit != null || cursorLimit != null) {
            cacheQuery.maxResults(
                Math.min(
                    limit == null ? Integer.MAX_VALUE : limit,
                    cursorLimit == null ? Integer.MAX_VALUE : cursorLimit));
        }
    }

    @Override
    protected void check() {
        if (checked.compareAndSet(false, true)) {
            checkInequalityConstraints();
        }
        if (holder.getIndex() == null) {
            Indexes.checkIfExplicitlyDefinedIndexIsRequired(holder.getQuery());
        }
        super.check();
    }

    private void checkInequalityConstraints() {
        if (Compatibility.getInstance().isEnabled(Compatibility.Feature.DISABLE_QUERY_INEQUALITY_FILTER_CHECK)) {
            return;
        }

        final Query query = holder.getQuery();
        String inequalityFilterProperty = checkInequalityConstraints(query.getFilter(), null);

        // legacy filters API can still be used, but I guess not both?
        if (inequalityFilterProperty == null) {
            //noinspection deprecation
            final List<Query.FilterPredicate> filterPredicates = query.getFilterPredicates();
            if (filterPredicates != null && filterPredicates.size() > 0) {
                for (Query.FilterPredicate predicate : filterPredicates) {
                    if (isInequalityOperator(predicate.getOperator())) {
                        if (inequalityFilterProperty == null) {
                            inequalityFilterProperty = predicate.getPropertyName();
                        } else {
                            if (!inequalityFilterProperty.equals(predicate.getPropertyName())) {
                                throw new IllegalArgumentException("Only one inequality filter per query is supported.  " +
                                        "Encountered both " + inequalityFilterProperty + " and " + predicate.getPropertyName());
                            }
                        }
                    }
                }
            }
        }

        if (inequalityFilterProperty != null && !query.getSortPredicates().isEmpty()) {
            Query.SortPredicate firstSortPredicate = query.getSortPredicates().get(0);
            String firstSortProperty = firstSortPredicate.getPropertyName();
            if (!firstSortProperty.equals(inequalityFilterProperty)) {
                throw new IllegalArgumentException("The first sort property must be the same as the property to which the " +
                        "inequality filter is applied.  In your query the first sort property is " + firstSortProperty + " " +
                        "but the inequality filter is on " + inequalityFilterProperty);
            }
        }
    }

    private String checkInequalityConstraints(Query.Filter filter, String inequalityFilterProperty) {
        if (filter instanceof Query.FilterPredicate) {
            Query.FilterPredicate predicate = (Query.FilterPredicate) filter;
            if (isInequalityOperator(predicate.getOperator())) {
                String property = predicate.getPropertyName();
                if (inequalityFilterProperty == null) {
                    return property;
                } else {
                    if (!inequalityFilterProperty.equals(property)) {
                        throw new IllegalArgumentException("Only one inequality filter per query is supported.  " +
                            "Encountered both " + inequalityFilterProperty + " and " + property);
                    }
                }
            }
        } else if (filter instanceof Query.CompositeFilter) {
            Query.CompositeFilter compositeFilter = (Query.CompositeFilter) filter;
            for (Query.Filter subFilter : compositeFilter.getSubFilters()) {
                String property = checkInequalityConstraints(subFilter, inequalityFilterProperty);
                if (property != null) {
                    inequalityFilterProperty = property;
                }
            }
        }
        return inequalityFilterProperty;
    }

    private boolean isInequalityOperator(Query.FilterOperator operator) {
        return operator != Query.FilterOperator.EQUAL && operator != Query.FilterOperator.IN;
    }
}