Examples with PrefetchProcessor org.apache.cayenne.query.PrefetchProcessor used on opensource projects

Example 1 with PrefetchProcessor

use of org.apache.cayenne.query.PrefetchProcessor in project cayenne by apache.

the class SelectAction method forSuppressedDistinct.

private <T> ResultIterator<T> forSuppressedDistinct(ResultIterator<T> iterator, SelectTranslator translator) {
    if (!translator.isSuppressingDistinct() || queryMetadata.isSuppressingDistinct()) {
        return iterator;
    }
    // wrap result iterator if distinct has to be suppressed
    // a joint prefetch warrants full row compare
    final boolean[] compareFullRows = new boolean[1];
    compareFullRows[0] = translator.hasJoins();
    final PrefetchTreeNode rootPrefetch = queryMetadata.getPrefetchTree();
    if (!compareFullRows[0] && rootPrefetch != null) {
        rootPrefetch.traverse(new PrefetchProcessor() {

            @Override
            public void finishPrefetch(PrefetchTreeNode node) {
            }

            @Override
            public boolean startDisjointPrefetch(PrefetchTreeNode node) {
                // continue to children only if we are at root
                return rootPrefetch == node;
            }

            @Override
            public boolean startDisjointByIdPrefetch(PrefetchTreeNode node) {
                // continue to children only if we are at root
                return rootPrefetch == node;
            }

            @Override
            public boolean startUnknownPrefetch(PrefetchTreeNode node) {
                // continue to children only if we are at root
                return rootPrefetch == node;
            }

            @Override
            public boolean startJointPrefetch(PrefetchTreeNode node) {
                if (rootPrefetch != node) {
                    compareFullRows[0] = true;
                    return false;
                }
                return true;
            }

            @Override
            public boolean startPhantomPrefetch(PrefetchTreeNode node) {
                return true;
            }
        });
    }
    return new DistinctResultIterator<>(iterator, queryMetadata.getDbEntity(), compareFullRows[0]);
}