play.classloading.enhancers.LocalvariablesNamesEnhancer Maven / Gradle / Ivy
package play.classloading.enhancers;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Stack;
import javassist.ClassPool;
import javassist.CtClass;
import javassist.CtConstructor;
import javassist.CtField;
import javassist.CtMethod;
import javassist.Modifier;
import javassist.bytecode.Bytecode;
import javassist.bytecode.CodeAttribute;
import javassist.bytecode.CodeIterator;
import javassist.bytecode.LocalVariableAttribute;
import javassist.bytecode.Opcode;
import javassist.compiler.Javac;
import javassist.compiler.NoFieldException;
import play.Logger;
import play.classloading.ApplicationClasses.ApplicationClass;
import play.exceptions.UnexpectedException;
/**
* Track names of local variables ...
*/
public class LocalvariablesNamesEnhancer extends Enhancer {
public static List lookupParameterNames(Constructor constructor) {
try {
List parameters = new ArrayList();
ClassPool classPool = newClassPool();
CtClass ctClass = classPool.get(constructor.getDeclaringClass().getName());
CtClass[] cc = new CtClass[constructor.getParameterTypes().length];
for (int i = 0; i < constructor.getParameterTypes().length; i++) {
cc[i] = classPool.get(constructor.getParameterTypes()[i].getName());
}
CtConstructor ctConstructor = ctClass.getDeclaredConstructor(cc);
// Signatures names
CodeAttribute codeAttribute = (CodeAttribute) ctConstructor.getMethodInfo().getAttribute("Code");
if (codeAttribute != null) {
LocalVariableAttribute localVariableAttribute = (LocalVariableAttribute) codeAttribute.getAttribute("LocalVariableTable");
if (localVariableAttribute != null && localVariableAttribute.tableLength() >= ctConstructor.getParameterTypes().length) {
for (int i = 0; i < ctConstructor.getParameterTypes().length + 1; i++) {
String name = localVariableAttribute.getConstPool().getUtf8Info(localVariableAttribute.nameIndex(i));
if (!name.equals("this")) {
parameters.add(name);
}
}
}
}
return parameters;
} catch(Exception e) {
throw new UnexpectedException("Cannot extract parameter names", e);
}
}
//
@Override
public void enhanceThisClass(ApplicationClass applicationClass) throws Exception {
CtClass ctClass = makeClass(applicationClass);
if (!ctClass.subtypeOf(classPool.get(LocalVariablesSupport.class.getName())) && !ctClass.getName().matches("^controllers\\..*\\$class$")) {
return;
}
for (CtMethod method : ctClass.getDeclaredMethods()) {
// Signatures names
CodeAttribute codeAttribute = (CodeAttribute) method.getMethodInfo().getAttribute("Code");
if (codeAttribute == null || javassist.Modifier.isAbstract(method.getModifiers())) {
continue;
}
LocalVariableAttribute localVariableAttribute = (LocalVariableAttribute) codeAttribute.getAttribute("LocalVariableTable");
if (localVariableAttribute == null || localVariableAttribute.tableLength() < method.getParameterTypes().length) {
if (method.getParameterTypes().length > 0) {
continue;
}
}
List names = new ArrayList();
for (int i = 0; i < method.getParameterTypes().length + (Modifier.isStatic(method.getModifiers()) ? 0 : 1); i++) {
if (localVariableAttribute == null) {
continue;
}
String name = localVariableAttribute.getConstPool().getUtf8Info(localVariableAttribute.nameIndex(i));
if (!name.equals("this")) {
names.add(name);
}
}
StringBuilder iv = new StringBuilder();
if (names.size() == 0) {
iv.append("new String[0];");
} else {
iv.append("new String[] {");
for (Iterator i = names.iterator(); i.hasNext();) {
iv.append("\"");
String aliasedName = i.next();
if (aliasedName.contains("$")) {
aliasedName = aliasedName.substring(0, aliasedName.indexOf("$"));
}
iv.append(aliasedName);
iv.append("\"");
if (i.hasNext()) {
iv.append(",");
}
}
iv.append("};");
}
CtField signature = CtField.make("public static String[] $" + method.getName() + LocalVariablesNamesTracer.computeMethodHash(method.getParameterTypes()) + " = " + iv.toString(), ctClass);
ctClass.addField(signature);
// No variable name, skip...
if (localVariableAttribute == null) {
continue;
}
// OK.
// Here after each local variable creation instruction,
// we insert a call to play.utils.LocalVariables.addVariable('var', var)
// without breaking everything...
for (int i = 0; i < localVariableAttribute.tableLength(); i++) {
// name of the local variable
String name = localVariableAttribute.getConstPool().getUtf8Info(localVariableAttribute.nameIndex(i));
// Normalize the variable name
// For several reasons, both variables name and name$1 will be aliased to name
String aliasedName = name;
if (aliasedName.contains("$")) {
aliasedName = aliasedName.substring(0, aliasedName.indexOf("$"));
}
if (name.equals("this")) {
continue;
}
/* DEBUG
IO.write(ctClass.toBytecode(), new File("/tmp/lv_"+applicationClass.name+".class"));
ctClass.defrost();
*/
try {
// The instruction at which this local variable has been created
Integer pc = localVariableAttribute.startPc(i);
// Move to the next instruction (insertionPc)
CodeIterator iterator = codeAttribute.iterator();
iterator.move(pc);
Integer insertionPc = iterator.next();
Javac jv = new Javac(ctClass);
// Compile the code snippet
jv.recordLocalVariables(codeAttribute, insertionPc);
jv.recordParams(method.getParameterTypes(), Modifier.isStatic(method.getModifiers()));
jv.setMaxLocals(codeAttribute.getMaxLocals());
jv.compileStmnt("play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.addVariable(\"" + aliasedName + "\", " + name + ");");
Bytecode b = jv.getBytecode();
int locals = b.getMaxLocals();
int stack = b.getMaxStack();
codeAttribute.setMaxLocals(locals);
if (stack > codeAttribute.getMaxStack()) {
codeAttribute.setMaxStack(stack);
}
iterator.insert(insertionPc, b.get());
iterator.insert(b.getExceptionTable(), insertionPc);
// Then we need to trace each affectation to the variable
CodeIterator codeIterator = codeAttribute.iterator();
// Bon chaque instruction de cette méthode
while (codeIterator.hasNext()) {
int index = codeIterator.next();
int op = codeIterator.byteAt(index);
// DEBUG
// printOp(op);
int varNumber = -1;
// The variable changes
if (storeByCode.containsKey(op)) {
varNumber = storeByCode.get(op);
if (varNumber == -2) {
varNumber = codeIterator.byteAt(index + 1);
}
}
// Si c'est un store de la variable en cours d'examination
// et que c'est dans la frame d'utilisation de cette variable on trace l'affectation.
// (en fait la frame commence à localVariableAttribute.startPc(i)-1 qui est la première affectation
// mais aussi l'initialisation de la variable qui est deja tracé plus haut, donc on commence à localVariableAttribute.startPc(i))
if (varNumber == localVariableAttribute.index(i) && index >= localVariableAttribute.startPc(i) && index < localVariableAttribute.startPc(i) + localVariableAttribute.codeLength(i)) {
jv.compileStmnt("play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.addVariable(\"" + aliasedName + "\", " + name + ");");
b = jv.getBytecode();
locals = b.getMaxLocals();
stack = b.getMaxStack();
codeAttribute.setMaxLocals(locals);
if (stack > codeAttribute.getMaxStack()) {
codeAttribute.setMaxStack(stack);
}
codeIterator.insert(b.get());
}
}
} catch (NoFieldException e) {
// Well probably a compiled optimizer (I hope so)
}
}
// init variable tracer
method.insertBefore("play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.enter();");
method.insertAfter("play.classloading.enhancers.LocalvariablesNamesEnhancer.LocalVariablesNamesTracer.exit();", true);
}
// Done.
applicationClass.enhancedByteCode = ctClass.toBytecode();
ctClass.defrost();
}
/**
* Mark class that need local variables tracking
*/
public static interface LocalVariablesSupport {
}
/**
* Runtime part.
*/
public static class LocalVariablesNamesTracer {
public static Integer computeMethodHash(CtClass[] parameters) {
String[] names = new String[parameters.length];
for (int i = 0; i < parameters.length; i++) {
names[i] = parameters[i].getName();
}
return computeMethodHash(names);
}
public static Integer computeMethodHash(Class[] parameters) {
String[] names = new String[parameters.length];
for (int i = 0; i < parameters.length; i++) {
Class param = parameters[i];
names[i] = "";
if (param.isArray()) {
int level = 1;
param = param.getComponentType();
// Array of array
while (param.isArray()) {
level++;
param = param.getComponentType();
}
names[i] = param.getName();
for (int j = 0; j < level; j++) {
names[i] += "[]";
}
} else {
names[i] = param.getName();
}
}
return computeMethodHash(names);
}
public static Integer computeMethodHash(String[] parameters) {
StringBuffer buffer = new StringBuffer();
for (String param : parameters) {
buffer.append(param);
}
Integer hash = buffer.toString().hashCode();
if (hash < 0) {
return -hash;
}
return hash;
}
static ThreadLocal>> localVariables = new ThreadLocal>>();
public static void checkEmpty() {
if (localVariables.get() != null && localVariables.get().size() != 0) {
Logger.error("LocalVariablesNamesTracer.checkEmpty, constraint violated (%s)", localVariables.get().size());
}
}
public static void clear() {
if (localVariables.get() != null) {
localVariables.set(null);
}
}
public static void enter() {
if (localVariables.get() == null) {
localVariables.set(new Stack>());
}
localVariables.get().push(new HashMap());
}
public static void exit() {
if (localVariables.get().isEmpty()) {
return;
}
localVariables.get().pop().clear();
}
public static Map locals() {
if (localVariables.get() != null && !localVariables.get().empty()) {
return localVariables.get().peek();
}
return new HashMap();
}
public static void addVariable(String name, Object o) {
locals().put(name, o);
}
public static void addVariable(String name, boolean b) {
locals().put(name, b);
}
public static void addVariable(String name, char c) {
locals().put(name, c);
}
public static void addVariable(String name, byte b) {
locals().put(name, b);
}
public static void addVariable(String name, double d) {
locals().put(name, d);
}
public static void addVariable(String name, float f) {
locals().put(name, f);
}
public static void addVariable(String name, int i) {
locals().put(name, i);
}
public static void addVariable(String name, long l) {
locals().put(name, l);
}
public static void addVariable(String name, short s) {
locals().put(name, s);
}
public static Map getLocalVariables() {
return locals();
}
public static List getAllLocalVariableNames(Object o) {
List allNames = new ArrayList();
for (String variable : getLocalVariables().keySet()) {
if (getLocalVariables().get(variable) == o) {
allNames.add(variable);
}
if (o != null && o instanceof Number && o.equals(getLocalVariables().get(variable))) {
allNames.add(variable);
}
}
return allNames;
}
public static Object getLocalVariable(String variable) {
return getLocalVariables().get(variable);
}
}
private static Map storeByCode = new HashMap();
/**
* Useful instructions
*/
static {
storeByCode.put(CodeIterator.ASTORE_0, 0);
storeByCode.put(CodeIterator.ASTORE_1, 1);
storeByCode.put(CodeIterator.ASTORE_2, 2);
storeByCode.put(CodeIterator.ASTORE_3, 3);
storeByCode.put(CodeIterator.ASTORE, -2);
storeByCode.put(CodeIterator.ISTORE_0, 0);
storeByCode.put(CodeIterator.ISTORE_1, 1);
storeByCode.put(CodeIterator.ISTORE_2, 2);
storeByCode.put(CodeIterator.ISTORE_3, 3);
storeByCode.put(CodeIterator.ISTORE, -2);
storeByCode.put(CodeIterator.IINC, -2);
storeByCode.put(CodeIterator.LSTORE_0, 0);
storeByCode.put(CodeIterator.LSTORE_1, 1);
storeByCode.put(CodeIterator.LSTORE_2, 2);
storeByCode.put(CodeIterator.LSTORE_3, 3);
storeByCode.put(CodeIterator.LSTORE, -2);
storeByCode.put(CodeIterator.FSTORE_0, 0);
storeByCode.put(CodeIterator.FSTORE_1, 1);
storeByCode.put(CodeIterator.FSTORE_2, 2);
storeByCode.put(CodeIterator.FSTORE_3, 3);
storeByCode.put(CodeIterator.FSTORE, -2);
storeByCode.put(CodeIterator.DSTORE_0, 0);
storeByCode.put(CodeIterator.DSTORE_1, 1);
storeByCode.put(CodeIterator.DSTORE_2, 2);
storeByCode.put(CodeIterator.DSTORE_3, 3);
storeByCode.put(CodeIterator.DSTORE, -2);
}
/**
* Debug utility. Display a byte code op as plain text.
*/
public static void printOp(int op) {
try {
for (Field f : Opcode.class.getDeclaredFields()) {
if (java.lang.reflect.Modifier.isStatic(f.getModifiers()) && java.lang.reflect.Modifier.isPublic(f.getModifiers()) && f.getInt(null) == op) {
System.out.println(op + " " + f.getName());
}
}
} catch (Exception e) {
}
}
}
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