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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.ArrayList;
import java.util.List;
import com.amazon.carbonado.Cursor;
import com.amazon.carbonado.FetchException;
import com.amazon.carbonado.PersistException;
import com.amazon.carbonado.RepositoryException;
import com.amazon.carbonado.Storable;
import com.amazon.carbonado.Transaction;
import com.amazon.carbonado.Trigger;
import com.amazon.carbonado.info.ChainedProperty;
/**
* Handles index updates for derived-to properties.
*
* @author Brian S O'Neill
* @since 1.2
*/
class DerivedIndexesTrigger<S extends Storable, D extends Storable> extends Trigger<S> {
private final DependentStorableFetcher<S, D> mFetcher;
/**
* @param derivedTo special chained property from StorableProperty.getDerivedToProperties
*/
DerivedIndexesTrigger(IndexedRepository repository,
Class<S> sType, ChainedProperty<D> derivedTo)
throws RepositoryException
{
this(new DependentStorableFetcher(repository, sType, derivedTo));
}
private DerivedIndexesTrigger(DependentStorableFetcher<S, D> fetcher) {
mFetcher = fetcher;
}
@Override
public Object beforeInsert(S storable) throws PersistException {
return createDependentIndexEntries(storable);
}
@Override
public void afterInsert(S storable, Object state) throws PersistException {
updateValues(storable, state);
}
@Override
public Object beforeUpdate(S storable) throws PersistException {
return createDependentIndexEntries(storable);
}
@Override
public void afterUpdate(S storable, Object state) throws PersistException {
updateValues(storable, state);
}
@Override
public Object beforeDelete(S storable) throws PersistException {
try {
if (storable.copy().tryLoad()) {
return createDependentIndexEntries(storable);
}
} catch (FetchException e) {
throw e.toPersistException();
}
return null;
}
@Override
public void afterDelete(S storable, Object state) throws PersistException {
updateValues(storable, state);
}
@Override
public int hashCode() {
return mFetcher.hashCode();
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof DerivedIndexesTrigger) {
DerivedIndexesTrigger other = (DerivedIndexesTrigger) obj;
return mFetcher.equals(other.mFetcher);
}
return false;
}
private List<Storable> createDependentIndexEntries(S storable) throws PersistException {
List<Storable> dependentIndexEntries = new ArrayList<Storable>();
createDependentIndexEntries(storable, dependentIndexEntries);
return dependentIndexEntries;
}
private void createDependentIndexEntries(S storable, List<Storable> dependentIndexEntries)
throws PersistException
{
try {
Transaction txn = mFetcher.enterTransaction();
try {
// Make sure write lock is acquired when reading dependencies
// since they might be updated later. Locks are held after this
// transaction exits since it is nested in the trigger's transaction.
txn.setForUpdate(true);
Cursor<D> dependencies = mFetcher.fetchDependenentStorables(storable);
try {
while (dependencies.hasNext()) {
mFetcher.createIndexEntries(dependencies.next(), dependentIndexEntries);
}
} finally {
dependencies.close();
}
} finally {
txn.exit();
}
} catch (FetchException e) {
throw e.toPersistException();
}
}
private void updateValues(S storable, Object state) throws PersistException {
if (state == null) {
return;
}
List<Storable> oldIndexEntries = (List<Storable>) state;
int size = oldIndexEntries.size();
List<Storable> newIndexEntries = new ArrayList<Storable>(size);
createDependentIndexEntries(storable, newIndexEntries);
if (size != newIndexEntries.size()) {
// This is not expected to happen.
throw new PersistException("Amount of affected dependent indexes changed: " +
size + " != " + newIndexEntries.size());
}
for (int i=0; i<size; i++) {
Storable oldIndexEntry = oldIndexEntries.get(i);
Storable newIndexEntry = newIndexEntries.get(i);
if (!oldIndexEntry.equalProperties(newIndexEntry)) {
// Try delete old entry, just in case it is missing.
oldIndexEntry.tryDelete();
}
// Always try to insert index entry, just in case it is missing.
newIndexEntry.tryInsert();
}
}
/**
* Ensure old storable instance is loaded with an upgradable lock, allowing change to
* proceed without deadlock.
*/
final static class Strict<S extends Storable, D extends Storable>
extends DerivedIndexesTrigger<S, D>
{
Strict(IndexedRepository repository,
Class<S> sType, ChainedProperty<D> derivedTo)
throws RepositoryException
{
super(repository, sType, derivedTo);
}
@Override
public Object beforeTryDelete(Transaction txn, S storable) throws PersistException {
return beforeDelete(txn, storable);
}
@Override
public Object beforeDelete(Transaction txn, S storable) throws PersistException {
txn.setForUpdate(true);
return super.beforeDelete(storable);
}
}
}
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