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/*
* Copyright 2006 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.spi;
import java.util.List;
import com.amazon.carbonado.FetchException;
import com.amazon.carbonado.PersistException;
import com.amazon.carbonado.Storable;
import com.amazon.carbonado.Trigger;
import com.amazon.carbonado.lob.Lob;
/**
*
*
* @author Brian S O'Neill
* @see LobEngine
*/
class LobEngineTrigger<S extends Storable> extends Trigger<S> {
final LobEngine mEngine;
private final int mBlockSize;
private final LobProperty<Lob>[] mLobProperties;
LobEngineTrigger(LobEngine engine, Class<S> type, int blockSize,
List<LobProperty<?>> lobProperties)
{
mEngine = engine;
mBlockSize = blockSize;
mLobProperties = new LobProperty[lobProperties.size()];
lobProperties.toArray(mLobProperties);
}
// Returns user specified Lob values
public Object beforeInsert(S storable) throws PersistException {
// Capture user lob values for later and replace with new locators.
int length = mLobProperties.length;
Object[] userLobs = new Object[length];
for (int i=0; i<length; i++) {
LobProperty<Lob> prop = mLobProperties[i];
Object userLob = storable.getPropertyValue(prop.mName);
userLobs[i] = userLob;
if (userLob != null) {
Object lob = prop.createNewLob(mBlockSize);
storable.setPropertyValue(prop.mName, lob);
}
}
return userLobs;
}
public void afterInsert(S storable, Object state) throws PersistException {
// Save user lob value contents into new lobs. This is done after the
// insert of the enclosing record to avoid an expensive rollback if a
// constraint violation is detected.
Object[] userLobs = (Object[]) state;
int length = mLobProperties.length;
for (int i=0; i<length; i++) {
Object userLob = userLobs[i];
if (userLob != null) {
LobProperty<Lob> prop = mLobProperties[i];
Lob lob = (Lob) storable.getPropertyValue(prop.mName);
prop.setLobValue(mEngine.getLocator(lob), (Lob) userLob);
}
}
}
public void failedInsert(S storable, Object state) {
unreplaceLobs(storable, state);
}
public Object beforeUpdate(S storable) throws PersistException {
// For each dirty lob property, capture it in case update fails. All
// lob updates are made in this method.
int length = mLobProperties.length;
Object[] userLobs = new Object[length];
S existing = null;
for (int i=0; i<length; i++) {
LobProperty<Lob> prop = mLobProperties[i];
if (!storable.isPropertyDirty(prop.mName)) {
continue;
}
try {
if (existing == null && (existing = loadExisting(storable)) == null) {
// Update will fail so don't touch lobs.
return null;
}
} catch (FetchException e) {
throw e.toPersistException();
}
Object userLob = storable.getPropertyValue(prop.mName);
userLobs[i] = userLob;
Lob existingLob = (Lob) existing.getPropertyValue(prop.mName);
if (userLob == null) {
if (existingLob != null) {
// User is setting existing lob to null, so delete it.
mEngine.deleteLob(existingLob);
}
} else {
if (existingLob == null) {
// User is setting a lob that has no locator yet, so make one.
existingLob = prop.createNewLob(mBlockSize);
}
prop.setLobValue(mEngine.getLocator(existingLob), (Lob) userLob);
storable.setPropertyValue(prop.mName, existingLob);
}
}
return userLobs;
}
public void failedUpdate(S storable, Object state) {
unreplaceLobs(storable, state);
}
// Returns existing Storable or null
public Object beforeDelete(S storable) throws PersistException {
S existing = (S) storable.copy();
try {
if (!existing.tryLoad()) {
existing = null;
}
return existing;
} catch (FetchException e) {
throw e.toPersistException();
}
}
public void afterDelete(S storable, Object existing) throws PersistException {
if (existing != null) {
// After successful delete of master storable, delete all the lobs.
for (LobProperty<Lob> prop : mLobProperties) {
Lob lob = (Lob) ((S) existing).getPropertyValue(prop.mName);
mEngine.deleteLob(lob);
}
}
}
private S loadExisting(S storable) throws FetchException {
S existing = (S) storable.copy();
if (!existing.tryLoad()) {
return null;
}
return existing;
}
private void unreplaceLobs(S storable, Object state) {
if (state != null) {
Object[] userLobs = (Object[]) state;
int length = mLobProperties.length;
for (int i=0; i<length; i++) {
Object userLob = userLobs[i];
if (userLob != null) {
storable.setPropertyValue(mLobProperties[i].mName, userLob);
}
}
}
}
}
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