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/*
* Copyright 2007-2012 Amazon Technologies, Inc. or its affiliates.
* Amazon, Amazon.com and Carbonado are trademarks or registered trademarks
* of Amazon Technologies, Inc. or its affiliates. All rights reserved.
*
* 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.amazon.carbonado.repo.indexed;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.List;
import com.amazon.carbonado.Cursor;
import com.amazon.carbonado.FetchException;
import com.amazon.carbonado.Query;
import com.amazon.carbonado.RepositoryException;
import com.amazon.carbonado.Storable;
import com.amazon.carbonado.SupportException;
import com.amazon.carbonado.Transaction;
import com.amazon.carbonado.filter.Filter;
import com.amazon.carbonado.filter.RelOp;
import com.amazon.carbonado.info.ChainedProperty;
import com.amazon.carbonado.info.StorableProperty;
/**
* Fetches Storables that have indexed derived-to properties which depend on S.
*
* @author Brian S O'Neill
* @since 1.2
*/
class DependentStorableFetcher<S extends Storable, D extends Storable> {
private final IndexedRepository mRepository;
private final IndexEntryAccessor<D>[] mIndexEntryAccessors;
private final Filter<D> mFilter;
private final String[] mJoinProperties;
private Query<D> mQuery;
/**
* @param derivedTo special chained property from StorableProperty.getDerivedToProperties
*/
DependentStorableFetcher(IndexedRepository repository,
Class<S> sType, ChainedProperty<D> derivedTo)
throws RepositoryException
{
if (derivedTo.getChainCount() == 0) {
throw new IllegalArgumentException();
}
if (derivedTo.getLastProperty().getType() != sType) {
throw new IllegalArgumentException();
}
if (!derivedTo.getLastProperty().isJoin()) {
throw new IllegalArgumentException();
}
Class<D> dType = derivedTo.getPrimeProperty().getEnclosingType();
// Find the indexes that contain the prime derivedTo property.
List<IndexEntryAccessor<D>> accessorList = new ArrayList<IndexEntryAccessor<D>>();
for (IndexEntryAccessor<D> acc : repository.getIndexEntryAccessors(dType)) {
for (String indexPropName : acc.getPropertyNames()) {
if (indexPropName.equals(derivedTo.getPrimeProperty().getName())) {
accessorList.add(acc);
break;
}
}
}
if (accessorList.size() == 0) {
throw new SupportException
("Unable to find index accessors for derived-to property: " + derivedTo +
", enclosing type: " + dType.getName() + ", source type: " + sType.getName());
}
// Build a query on D joined to S.
StorableProperty<S> join = (StorableProperty<S>) derivedTo.getLastProperty();
ChainedProperty<?> base;
if (derivedTo.getChainCount() <= 1) {
base = null;
} else {
base = derivedTo.tail().trim();
}
int joinElementCount = join.getJoinElementCount();
String[] joinProperties = new String[joinElementCount];
Filter<D> dFilter = Filter.getOpenFilter(dType);
for (int i=0; i<joinElementCount; i++) {
joinProperties[i] = join.getExternalJoinElement(i).getName();
StorableProperty<S> internal = join.getInternalJoinElement(i);
if (base == null) {
dFilter = dFilter.and(internal.getName(), RelOp.EQ);
} else {
dFilter = dFilter.and(base.append(internal).toString(), RelOp.EQ);
}
}
mRepository = repository;
mIndexEntryAccessors = accessorList.toArray(new IndexEntryAccessor[accessorList.size()]);
mFilter = dFilter;
mJoinProperties = joinProperties;
}
public Transaction enterTransaction() {
return mRepository.enterTransaction();
}
public Cursor<D> fetchDependenentStorables(S storable) throws FetchException {
Query<D> query = query();
for (String property : mJoinProperties) {
query = query.with(storable.getPropertyValue(property));
}
return query.fetch();
}
/**
* @return amount added to list
*/
public int createIndexEntries(D master, List<Storable> indexEntries) throws FetchException {
IndexEntryAccessor[] accessors = mIndexEntryAccessors;
int length = accessors.length;
for (int i=0; i<length; i++) {
IndexEntryAccessor accessor = accessors[i];
Storable indexEntry = accessor.getIndexEntryStorage().prepare();
accessor.copyFromMaster(indexEntry, master);
indexEntries.add(indexEntry);
}
return length;
}
@Override
public int hashCode() {
return mFilter.hashCode();
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof DependentStorableFetcher) {
DependentStorableFetcher other = (DependentStorableFetcher) obj;
return mFilter.equals(other.mFilter)
&& Arrays.equals(mJoinProperties, other.mJoinProperties)
&& Arrays.equals(mIndexEntryAccessors, other.mIndexEntryAccessors);
}
return false;
}
@Override
public String toString() {
return "DependentStorableFetcher: {indexes=" + Arrays.toString(mIndexEntryAccessors) +
", filter=" + mFilter +
", join properties=" + Arrays.toString(mJoinProperties) + '}';
}
private Query<D> query() throws FetchException {
// Query is lazily created to avoid stack overflow due to cyclic
// dependencies.
Query<D> query = mQuery;
if (query == null) {
try {
mQuery = query = mRepository.storageFor(mFilter.getStorableType()).query(mFilter);
} catch (RepositoryException e) {
throw e.toFetchException();
}
}
return query;
}
}
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