/*******************************************************************************
* Copyright (c) 1998, 2015 Oracle and/or its affiliates. All rights reserved.
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v1.0 and Eclipse Distribution License v. 1.0
* which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
* and the Eclipse Distribution License is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* Contributors:
* Oracle - initial API and implementation from Oracle TopLink
******************************************************************************/
package org.eclipse.persistence.testing.tests.dbchangenotification;
import java.util.*;
import org.eclipse.persistence.sessions.Session;
import org.eclipse.persistence.descriptors.ClassDescriptor;
import org.eclipse.persistence.sessions.DatabaseRecord;
/**
* This class translates a database change notification message
* into invalidation of a corresponding object in TopLink cache.
*
* The class expects the invalidation notification to be found in the following
* JMSMessage properties:
* String property "TABLE" should contain table name;
* Properties of appropriate type should contain value(s) of PK field(s).
*
* Examples based on Employee demo:
* 1. EMPLOYEE table:
* getStringProperty("TABLE") == "EMPLOYEE";
* getObjectProperty("EMP_ID") == value of EMP_ID column for the modified row
*
* 2. SALARY table:
* getStringProperty("TABLE") == "SALARY";
* getObjectProperty("EMP_ID") == value of EMP_ID column for the modified row
*
* 3. PHONE table:
* getStringProperty("TABLE") == "PHONE";
* getObjectProperty("EMP_ID") == value of EMP_ID column for the modified row
* getObjectProperty("TYPE") == value of TYPE column for the modified row
*/
public class
CacheInvalidator {
// maps a table name to Class mapped to this table
Hashtable tableNameToClass;
// maps table name to a vector of primary key fields' names
Hashtable tableNameToPkFieldNames;
// Create a CacheInvalidator object that invalidates cache if the changed table
// is mapped by one of the descriptors of the passed session
public CacheInvalidator(Session session) {
// HashSet is used to avoid duplications
HashSet tableNames = new HashSet();
// fill out tableNames collection with all tables' names mapped by all descriptors
Iterator descriptors = session.getDescriptors().values().iterator();
while (descriptors.hasNext()) {
ClassDescriptor desc = (ClassDescriptor)descriptors.next();
// Create a Vector containing names of all tables mapped to the descriptor
Vector descTableNames = desc.getTableNames();
// Remove schema names (if any) converting "SCHEMA_NAME.TABLE_NAME" to "TABLE_NAME"
removePrefixFromDatabaseObjectNames(descTableNames);
// add descTableNames to the collection
tableNames.addAll(descTableNames);
}
// initialize
initializeWithTableNames(session, tableNames);
}
// Create a CacheInvalidator object that invalidates cache if the changed table's name
// is in tableNames collection
// and the table is mapped by one of the descriptors of the passed session.
// Note that the Collection tableNames will be altered - only names
// of tables not found in descriptors of the passed session will remain.
public CacheInvalidator(Session session, Collection tableNames) {
// initialize
initializeWithTableNames(session, tableNames);
}
protected void initializeWithTableNames(Session session, Collection tableNames) {
tableNameToClass = new Hashtable(tableNames.size());
tableNameToPkFieldNames = new Hashtable(tableNames.size());
// pkFieldVectors cached here to avoid calculating it more than once per class
Hashtable classToPkFieldNames = new Hashtable();
// loop through the descriptors to fill out tableNameToClass and tableNameToPkFieldNames
Iterator descriptors = session.getDescriptors().values().iterator();
while (descriptors.hasNext() && !tableNames.isEmpty()) {
ClassDescriptor desc = (ClassDescriptor)descriptors.next();
// Create a Vector containing names of all tables mapped to the descriptor
Vector descTableNames = desc.getTableNames();
// bypass descriptors with no tables
if (descTableNames.isEmpty()) {
continue;
}
// Remove schema names (if any) converting "SCHEMA_NAME.TABLE_NAME" to "TABLE_NAME"
removePrefixFromDatabaseObjectNames(descTableNames);
// handle inheritance: table name should be mapped to the base mapped class
Class baseClass = desc.getJavaClass();
while (desc.isChildDescriptor()) {
desc = session.getDescriptor(desc.getInheritancePolicy().getParentClass());
baseClass = desc.getJavaClass();
}
Iterator it = tableNames.iterator();
while (it.hasNext()) {
// for each tableName specified by the user
String tableName = (String)it.next();
// verify whether the descriptor maps a table with the same name
if (descTableNames.contains(tableName)) {
// map the table name to the baseClass corresponding to the descriptor
tableNameToClass.put(tableName, baseClass);
// try to obtain cached pkFieldNames Vector corresponding to baseClass
Vector pkFieldNames = (Vector)classToPkFieldNames.get(baseClass);
if (pkFieldNames == null) {
// Create a Vector containing names of all primary key fields
pkFieldNames = desc.getPrimaryKeyFieldNames();
// Remove table name converting from "TABLE_NAME.FIELD_NAME" to "FIELD_NAME"
removePrefixFromDatabaseObjectNames(pkFieldNames);
// cache pkFieldNames Vector corresponding to baseClass
classToPkFieldNames.put(baseClass, pkFieldNames);
}
// map the table name to the Vector of names of primary key fields.
tableNameToPkFieldNames.put(tableName, pkFieldNames);
// the table name is mapped - remove it from the list of table names to be mapped.
it.remove();
}
}
}
}
// invalidates in tjhe cache the object corresponding to the massage
public void invalidateObject(Session session, javax.jms.Message msg) throws javax.jms.JMSException {
String tableName = msg.getStringProperty("TABLE");
if (tableName == null) {
return;
}
Class baseClass = (Class)tableNameToClass.get(tableName);
if (baseClass == null) {
return;
}
Vector pkFieldNames = (Vector)tableNameToPkFieldNames.get(tableName);
if (pkFieldNames == null) {
return;
}
// create DatabaseRecord corresponding to the message
DatabaseRecord row = new DatabaseRecord(pkFieldNames.size());
for (int i = 0; i < pkFieldNames.size(); i++) {
String fieldName = (String)pkFieldNames.elementAt(i);
Object value = msg.getObjectProperty(fieldName);
row.put(fieldName, value);
}
// invalidate in TopLink cache the object corresponding to the row and the baseClass
session.getIdentityMapAccessor().invalidateObject(row, baseClass);
}
// converts "SCHEMA_NAME.TABLE_NAME" to "TABLE_NAME"
protected void removePrefixFromDatabaseObjectNames(Vector names) {
for (int i = 0; i < names.size(); i++) {
String qualifiedName = (String)names.elementAt(i);
String name = qualifiedName.substring(qualifiedName.lastIndexOf('.') + 1);
names.setElementAt(name, i);
}
}
}