/**
* Copyright 2013 Impetus Infotech.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.impetus.client.cassandra.query;
import java.lang.reflect.Field;
import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;
import javax.persistence.PersistenceException;
import javax.persistence.Query;
import javax.persistence.metamodel.Attribute;
import javax.persistence.metamodel.EmbeddableType;
import org.apache.cassandra.thrift.IndexClause;
import org.apache.cassandra.thrift.IndexExpression;
import org.apache.commons.lang.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.impetus.client.cassandra.CassandraClientBase;
import com.impetus.client.cassandra.common.CassandraUtilities;
import com.impetus.client.cassandra.index.CassandraIndexHelper;
import com.impetus.client.cassandra.thrift.CQLTranslator;
import com.impetus.kundera.client.Client;
import com.impetus.kundera.client.ClientBase;
import com.impetus.kundera.client.EnhanceEntity;
import com.impetus.kundera.metadata.MetadataUtils;
import com.impetus.kundera.metadata.model.ApplicationMetadata;
import com.impetus.kundera.metadata.model.EntityMetadata;
import com.impetus.kundera.metadata.model.MetamodelImpl;
import com.impetus.kundera.metadata.model.attributes.AbstractAttribute;
import com.impetus.kundera.persistence.EntityManagerFactoryImpl.KunderaMetadata;
import com.impetus.kundera.persistence.EntityReader;
import com.impetus.kundera.property.PropertyAccessorHelper;
import com.impetus.kundera.query.IResultIterator;
import com.impetus.kundera.query.KunderaQuery.FilterClause;
import com.impetus.kundera.query.QueryImpl;
import com.impetus.kundera.utils.ReflectUtils;
/**
* @author vivek.mishra .
*
* Implementation of Cassandra result iteration.
*
* TODO::: Need to add support for relational entities and a junit for
* Composite key test
*/
class ResultIterator<E> implements IResultIterator<E>
{
private static Logger log = LoggerFactory.getLogger(ResultIterator.class);
private final CassQuery query;
private final EntityMetadata entityMetadata;
private final Client client;
private final EntityReader reader;
private int maxResult = 1;
private List<E> results;
private byte[] start;
private static final String MIN_ = "min";
private static final String MAX_ = "max";
private int fetchSize;
private int count;
private boolean scrollComplete;
private Map<String, Object> externalProperties;
private E current;
private final KunderaMetadata kunderaMetadata;
/**
* Constructor with parameters
*
* @param query
* @param m
* @param client
* @param reader
* @param fetchSize
*/
ResultIterator(final Query query, final EntityMetadata m, final Client client, final EntityReader reader,
final int fetchSize, final KunderaMetadata kunderaMetadata)
{
this.client = client;
this.query = (CassQuery) query;
this.entityMetadata = m;
this.reader = reader;
this.scrollComplete = false;
this.fetchSize = fetchSize;
this.kunderaMetadata = kunderaMetadata;
}
@Override
public boolean hasNext()
{
if (checkOnFetchSize())
{
onCheckRelation();
if (!checkOnEmptyResult())
{
scrollComplete = true;
return false;
}
return true;
}
return false;
}
@Override
public E next()
{
if (current != null && checkOnEmptyResult() && current.equals(results.get(results.size() - 1)))
{
hasNext();
}
if (scrollComplete)
{
throw new NoSuchElementException("Nothing to scroll further for:" + entityMetadata.getEntityClazz());
}
E lastFetchedEntity = getEntity(results.get(results.size() - 1));
start = lastFetchedEntity != null ? idValueInByteArr() : null;
current = getEntity(results.get(results.size() - 1));
return current;
}
@Override
public void remove()
{
throw new UnsupportedOperationException("remove method is not supported over pagination");
}
@Override
public List<E> next(int chunkSize)
{
throw new UnsupportedOperationException("fetch in chunks is not yet supported");
}
/**
* Check on fetch size. returns true, if count on fetched rows is less than
* fetch size.
*
* @return
*/
private boolean checkOnFetchSize()
{
if (count++ < fetchSize)
{
return true;
}
count = 0;
scrollComplete = true;
return false;
}
/**
* on check relation event, invokes populate entities and set relational
* entities, in case relations are present.
*/
private void onCheckRelation()
{
try
{
results = populateEntities(entityMetadata, client);
if (entityMetadata.isRelationViaJoinTable()
|| (entityMetadata.getRelationNames() != null && !(entityMetadata.getRelationNames().isEmpty())))
{
query.setRelationalEntities(results, client, entityMetadata);
}
}
catch (Exception e)
{
throw new PersistenceException("Error while scrolling over results, Caused by :.", e);
}
}
/**
* Method parse provided JPQL query into: 1. CQL3 query, in case cql3 is
* enabled or is a native query. 2. list of index clause, if cql2 is
* enabled. Then executes query for given min & max values for scrolling
* over results.
*
* @param m
* entity metadata
* @param client
* client
* @return list of database values wrapped into entities.
* @throws Exception
* throws exception, in case of run time error.
*/
private List<E> populateEntities(EntityMetadata m, Client client) throws Exception
{
if (log.isDebugEnabled())
{
log.debug("Populating entities for Cassandra query {}.", ((QueryImpl) query).getJPAQuery());
}
List<E> result = new ArrayList<E>();
ApplicationMetadata appMetadata = kunderaMetadata.getApplicationMetadata();
externalProperties = ((CassandraClientBase) client).getExternalProperties();
// if id attribute is embeddable, it is meant for CQL translation.
// make it independent of embedded stuff and allow even to add non
// composite into where clause and let cassandra complain for it.
MetamodelImpl metaModel = (MetamodelImpl) kunderaMetadata.getApplicationMetadata().getMetamodel(
m.getPersistenceUnit());
String queryString = appMetadata.getQuery(((QueryImpl) query).getJPAQuery());
boolean isNative = ((CassQuery) query).isNative();
if (((CassandraClientBase) client).isCql3Enabled(m))
{
String parsedQuery = query.onQueryOverCQL3(m, client, metaModel, null);
parsedQuery = appendWhereClauseWithScroll(parsedQuery);
results = parsedQuery != null ? ((CassandraClientBase) client).executeQuery(m.getEntityClazz(),
m.getRelationNames(), isNative, parsedQuery) : null;
}
else
{
// Index in Inverted Index table if applicable
boolean useInvertedIndex = CassandraIndexHelper.isInvertedIndexingApplicable(m,
MetadataUtils.useSecondryIndex(((ClientBase) client).getClientMetadata()));
Map<Boolean, List<IndexClause>> ixClause = query.prepareIndexClause(m, useInvertedIndex);
if (useInvertedIndex && !((QueryImpl) query).getKunderaQuery().getFilterClauseQueue().isEmpty())
{
result = (List) ((CassandraEntityReader) this.reader).readFromIndexTable(m, client, ixClause);
}
else
{
boolean isRowKeyQuery = ixClause.keySet().iterator().next();
List<IndexExpression> expressions = !ixClause.get(isRowKeyQuery).isEmpty() ? ixClause
.get(isRowKeyQuery).get(0).getExpressions() : null;
Map<String, byte[]> rowKeys = ((CassandraEntityReader) this.reader).getRowKeyValue(expressions,
((AbstractAttribute) m.getIdAttribute()).getJPAColumnName());
byte[] minValue = start == null ? rowKeys.get(MIN_) : start;
byte[] maxVal = rowKeys.get(MAX_);
results = ((CassandraClientBase) client).findByRange(minValue, maxVal, m, m.getRelationNames() != null
&& !m.getRelationNames().isEmpty(), m.getRelationNames(),
query.getColumnList(m, metaModel, ((QueryImpl) query).getKunderaQuery().getResult(), null),
expressions, maxResult);
if (maxResult == 1)
{
maxResult++;
}
else if (maxResult > 1 && checkOnEmptyResult() && maxResult != results.size())
{
// means iterating over last record only, so need for
// database trip anymore!.
results = null;
}
}
}
return results;
}
/**
* Appends where claues and prepare for next fetch. Method to be called in
* case cql3 enabled.
*
* @param parsedQuery
* parsed query.
*
* @return cql3 query to be executed.
*/
private String appendWhereClauseWithScroll(String parsedQuery)
{
String queryWithoutLimit = parsedQuery.replaceAll(
parsedQuery.substring(parsedQuery.lastIndexOf(CQLTranslator.LIMIT), parsedQuery.length()), "");
CQLTranslator translator = new CQLTranslator();
final String tokenCondition = prepareNext(translator, queryWithoutLimit);
StringBuilder builder = new StringBuilder(queryWithoutLimit);
if (tokenCondition != null)
{
if (query.getKunderaQuery().getFilterClauseQueue().isEmpty())
{
builder.append(CQLTranslator.ADD_WHERE_CLAUSE);
}
else
{
builder.append(CQLTranslator.AND_CLAUSE);
}
builder.append(tokenCondition);
}
String replaceQuery = replaceAndAppendLimit(builder.toString());
builder.replace(0, builder.toString().length(), replaceQuery);
translator.buildFilteringClause(builder);
// in case of fetch by ID, token condition will be null and results will
// not be empty.
return checkOnEmptyResult() && tokenCondition == null ? null : builder.toString();
}
/**
* Replace and append limit.
*
* @param parsedQuery
* parsed cql3 query.
*
* @return cql3 query appended with limit clause.
*/
private String replaceAndAppendLimit(String parsedQuery)
{
StringBuilder builder = new StringBuilder(parsedQuery);
onLimit(builder);
parsedQuery = builder.toString();
return parsedQuery;
}
/**
* Append limit to sql3 query.
*
* @param builder
* builder instance.
*/
private void onLimit(StringBuilder builder)
{
builder.append(CQLTranslator.LIMIT);
builder.append(this.maxResult);
}
/**
* Parse and append cql3 token function for iter.next() call.
*
* @param translator
* cql translator.
*
* @return parsed/append cql3 query.
*/
private String prepareNext(CQLTranslator translator, String query)
{
if (checkOnEmptyResult())
{
String idName = ((AbstractAttribute) entityMetadata.getIdAttribute()).getJPAColumnName();
Map<Boolean, String> filterOnId = getConditionOnIdColumn(idName);
if (filterOnId.get(true) != null)
{
String condition = filterOnId.get(true);
// means id clause present in query.
// now if id attribute is embeddable then fetch partition key
// for token
// if condition is with equals then no need to go for another
// fetch.
if (condition.equals("="))
{
// no need to fetch another record, as there will be only
// one
return null;
}
else if (condition.endsWith(">") || condition.equals(">="))
{
query = replaceAppliedToken(query);
return query;
}
}
// Means there is an previous entity.
Object entity = results.get(results.size() - 1);
Class idClazz = ((AbstractAttribute) entityMetadata.getIdAttribute()).getBindableJavaType();
Object id = PropertyAccessorHelper.getId(entity, entityMetadata);
StringBuilder builder = new StringBuilder(CQLTranslator.TOKEN);
MetamodelImpl metaModel = (MetamodelImpl) kunderaMetadata.getApplicationMetadata().getMetamodel(
entityMetadata.getPersistenceUnit());
EmbeddableType keyObj = null;
// Bytes bytes = null;
String columnName;
if (metaModel.isEmbeddable(entityMetadata.getIdAttribute().getBindableJavaType()))
{
keyObj = metaModel.embeddable(entityMetadata.getIdAttribute().getBindableJavaType());
Field embeddedField = getPartitionKeyField();
Attribute partitionKey = keyObj.getAttribute(embeddedField.getName());
Object partitionKeyValue = PropertyAccessorHelper.getObject(id, (Field) partitionKey.getJavaMember());
columnName = ((AbstractAttribute) partitionKey).getJPAColumnName();
id = partitionKeyValue;
idClazz = ((AbstractAttribute) partitionKey).getBindableJavaType();
}
else
{
columnName = CassandraUtilities.getIdColumnName(kunderaMetadata, entityMetadata, externalProperties,
((CassandraClientBase) client).isCql3Enabled(entityMetadata));
}
translator.appendColumnName(builder, columnName);
builder.append(CQLTranslator.CLOSE_BRACKET);
builder.append(" > ");
builder.append(CQLTranslator.TOKEN);
translator.appendValue(builder, idClazz, id, false, false);
builder.append(CQLTranslator.CLOSE_BRACKET);
return builder.toString();
}
return null;
}
/**
*
* @param idColumn
* @return
*/
private Map<Boolean, String> getConditionOnIdColumn(String idColumn)
{
Map<Boolean, String> filterIdResult = new HashMap<Boolean, String>();
MetamodelImpl metaModel = (MetamodelImpl) kunderaMetadata.getApplicationMetadata().getMetamodel(
entityMetadata.getPersistenceUnit());
EmbeddableType keyObj = null;
if (metaModel.isEmbeddable(entityMetadata.getIdAttribute().getBindableJavaType()))
{
keyObj = metaModel.embeddable(entityMetadata.getIdAttribute().getBindableJavaType());
}
for (Object o : query.getKunderaQuery().getFilterClauseQueue())
{
if (o instanceof FilterClause)
{
FilterClause clause = ((FilterClause) o);
String fieldName = clause.getProperty();
String condition = clause.getCondition();
if (keyObj != null && fieldName.equals(idColumn)
|| (keyObj != null && StringUtils.contains(fieldName, '.')) || (idColumn.equals(fieldName)))
{
filterIdResult.put(true, condition);
break;
}
}
}
return filterIdResult;
}
private byte[] idValueInByteArr()
{
Object entity = results.get(results.size() - 1);
Object id = PropertyAccessorHelper.getId(entity, entityMetadata);
String idName = ((AbstractAttribute) entityMetadata.getIdAttribute()).getJPAColumnName();
Class idClazz = ((AbstractAttribute) entityMetadata.getIdAttribute()).getBindableJavaType();
MetamodelImpl metaModel = (MetamodelImpl) kunderaMetadata.getApplicationMetadata().getMetamodel(
entityMetadata.getPersistenceUnit());
EmbeddableType keyObj = null;
ByteBuffer bytes = null;
// if the key attribute is composite
if (metaModel.isEmbeddable(entityMetadata.getIdAttribute().getBindableJavaType()))
{
keyObj = metaModel.embeddable(entityMetadata.getIdAttribute().getBindableJavaType());
Field embeddedField = getPartitionKeyField();
Attribute partitionKey = keyObj.getAttribute(embeddedField.getName());
Object partitionKeyValue = PropertyAccessorHelper.getObject(id, (Field) partitionKey.getJavaMember());
bytes = CassandraUtilities.toBytes(partitionKeyValue, (Field) partitionKey.getJavaMember());
}
else
{
bytes = query.getBytesValue(idName, entityMetadata, id);
}
return bytes.array();
}
/**
* Will return partition key part of composite id.
*
* @return
*/
private Field getPartitionKeyField()
{
Field[] embeddedFields = entityMetadata.getIdAttribute().getBindableJavaType().getDeclaredFields();
Field field = null;
for (Field embeddedField : embeddedFields)
{
if (!ReflectUtils.isTransientOrStatic(embeddedField))
{
field = embeddedField;
break;
}
}
return field;
}
/**
* check if result list is null or empty. Returns true, if it is not empty
* or null.
*
* @return boolean value (true/false).
*
*/
private boolean checkOnEmptyResult()
{
return results != null && !results.isEmpty();
}
/**
* Extract wrapped entity object from enhanced entity.
*
* @param entity
* enhanced entity.
*
* @return returns extracted instance of E.
*/
private E getEntity(Object entity)
{
return (E) (entity.getClass().isAssignableFrom(EnhanceEntity.class) ? ((EnhanceEntity) entity).getEntity()
: entity);
}
private String replaceAppliedToken(String query)
{
final String tokenRegex = "\\btoken\\(";
final String pattern = "#TOKENKUNDERA#"; // need to replace with this as
// pattern matcher was
// returning false.
query = query.replaceAll(tokenRegex, pattern);
if (query.indexOf(pattern) > -1) // Means token( has been present and
// replaced.
{
CQLTranslator translator = new CQLTranslator();
int closingIndex = query.indexOf(CQLTranslator.CLOSE_BRACKET, query.lastIndexOf(pattern));
String object = query.substring(query.lastIndexOf(pattern) + pattern.length(), closingIndex);
Object entity = results.get(results.size() - 1);
Class idClazz = ((AbstractAttribute) entityMetadata.getIdAttribute()).getBindableJavaType();
Object id = PropertyAccessorHelper.getId(entity, entityMetadata);
StringBuilder builder = new StringBuilder();
translator.appendValue(builder, idClazz, id, false, false);
query = query.replaceAll(pattern + object, pattern + builder.toString());
query = query.replaceAll(pattern, CQLTranslator.TOKEN);
}
return query;
}
}