/*
* Copyright (c) 2003, 2007, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*
*/
package sun.jvm.hotspot.utilities.soql;
import java.util.*;
import sun.jvm.hotspot.oops.*;
import sun.jvm.hotspot.memory.*;
import sun.jvm.hotspot.runtime.*;
import sun.jvm.hotspot.utilities.*;
/**
* This is SOQL (Simple Object Query Language) engine. This
* uses JavaScript engine for the "select" and "where" expression
* parts.
*/
public class SOQLEngine extends JSJavaScriptEngine {
public static synchronized SOQLEngine getEngine() {
if (soleInstance == null) {
soleInstance = new SOQLEngine();
}
return soleInstance;
}
/**
Query is of the form
select <java script code to select>
[ from [instanceof] <class name> [<identifier>]
[ where <java script boolean expression> ]
]
*/
public synchronized void executeQuery(String query, ObjectVisitor visitor)
throws SOQLException {
debugPrint("query : " + query);
StringTokenizer st = new StringTokenizer(query);
if (st.hasMoreTokens()) {
String first = st.nextToken();
if (! first.equals("select") ) {
throw new SOQLException("query syntax error: no 'select' clause");
}
} else {
throw new SOQLException("query syntax error: no 'select' clause");
}
int selectStart = query.indexOf("select");
int fromStart = query.indexOf("from");
String selectExpr = null;
String className = null;
boolean isInstanceOf = false;
String whereExpr = null;
String identifier = null;
if (fromStart != -1) {
selectExpr = query.substring(selectStart + "select".length(), fromStart);
st = new StringTokenizer(query.substring(fromStart + "from".length()));
if (st.hasMoreTokens()) {
String tmp = st.nextToken();
if (tmp.equals("instanceof")) {
isInstanceOf = true;
if (! st.hasMoreTokens()) {
throw new SOQLException("no class name after 'instanceof'");
}
className = st.nextToken();
} else {
className = tmp;
}
} else {
throw new SOQLException("query syntax error: class name must follow 'from'");
}
if (st.hasMoreTokens()) {
identifier = st.nextToken();
if (identifier.equals("where")) {
throw new SOQLException("query syntax error: identifier should follow class name");
}
if (st.hasMoreTokens()) {
String tmp = st.nextToken();
if (! tmp.equals("where")) {
throw new SOQLException("query syntax error: 'where' clause expected after 'from' clause");
}
int whereEnd = query.lastIndexOf("where") + 5; // "where".length
whereExpr = query.substring(whereEnd);
}
} else {
throw new SOQLException("query syntax error: identifier should follow class name");
}
} else { // no from clause
selectExpr = query.substring(selectStart + "select".length(), query.length());
}
executeQuery(new SOQLQuery(selectExpr, isInstanceOf, className, identifier, whereExpr), visitor);
}
private void executeQuery(SOQLQuery q, ObjectVisitor visitor) throws SOQLException {
InstanceKlass kls = null;
if (q.className != null) {
kls = SystemDictionaryHelper.findInstanceKlass(q.className);
if (kls == null) {
throw new SOQLException(q.className + " is not found!");
}
}
StringBuffer buf = new StringBuffer();
buf.append("function result(");
if (q.identifier != null) {
buf.append(q.identifier);
}
buf.append(") { return ");
buf.append(q.selectExpr.replace('\n', ' '));
buf.append("; }");
String selectCode = buf.toString();
debugPrint(selectCode);
String whereCode = null;
if (q.whereExpr != null) {
buf = new StringBuffer();
buf.append("function filter(");
buf.append(q.identifier);
buf.append(") { return ");
buf.append(q.whereExpr.replace('\n', ' '));
buf.append("; }");
whereCode = buf.toString();
debugPrint(whereCode);
} else {
whereCode = "filter = null;";
}
beginQuery();
// compile select expression and where condition
evalString(selectCode, "", 1);
evalString(whereCode, "", 1);
// iterate thru heap, if needed
if (q.className != null) {
try {
iterateOops(kls, visitor, q.isInstanceOf);
} finally {
endQuery();
}
} else {
// simple "select <expr>" query
try {
Object select = call("result", new Object[] {});
visitor.visit(select);
} catch (Exception e) {
e.printStackTrace();
}
}
}
private void dispatchObject(Oop oop, ObjectVisitor visitor, boolean filterExists) {
JSJavaObject jsObj = factory.newJSJavaObject(oop);
Object[] args = new Object[] { jsObj };
boolean b = true;
try {
if (filterExists) {
Object res = call("filter", args);
if (res instanceof Boolean) {
b = ((Boolean)res).booleanValue();
} else if (res instanceof Number) {
b = ((Number)res).intValue() != 0;
} else {
b = (res != null);
}
}
if (b) {
Object select = call("result", args);
visitor.visit(select);
}
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private void iterateOops(final InstanceKlass ik, final ObjectVisitor visitor,
boolean includeSubtypes) {
ObjectHeap oh = VM.getVM().getObjectHeap();
oh.iterateObjectsOfKlass(new HeapVisitor() {
boolean filterExists;
public void prologue(long usedSize) {
filterExists = getScriptEngine().get("filter") != null;
}
public boolean doObj(Oop obj) {
dispatchObject(obj, visitor, filterExists);
return false;
}
public void epilogue() {}
}, ik, includeSubtypes);
}
// we create fresh ObjectReader and factory to avoid
// excessive cache across queries.
private void beginQuery() {
objReader = new ObjectReader();
factory = new JSJavaFactoryImpl();
}
// at the end of query we clear object reader cache
// and factory cache
private void endQuery() {
objReader = null;
factory = null;
}
protected ObjectReader getObjectReader() {
return objReader;
}
protected JSJavaFactory getJSJavaFactory() {
return factory;
}
protected boolean isQuitting() {
return false;
}
protected void quit() {
// do nothing
}
private static void debugPrint(String msg) {
if (debug) System.out.println(msg);
}
private static final boolean debug;
static {
debug = System.getProperty("sun.jvm.hotspot.utilities.soql.SOQLEngine.debug") != null;
}
protected SOQLEngine() {
super(debug);
start();
}
private ObjectReader objReader;
private JSJavaFactory factory;
private static SOQLEngine soleInstance;
}