/*
* FindBugs - Find Bugs in Java programs
* Copyright (C) 2006, University of Maryland
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package edu.umd.cs.findbugs.detect;
import org.apache.bcel.classfile.Code;
import edu.umd.cs.findbugs.BugInstance;
import edu.umd.cs.findbugs.BugReporter;
import edu.umd.cs.findbugs.OpcodeStack;
import edu.umd.cs.findbugs.ba.XClass;
import edu.umd.cs.findbugs.ba.XMethod;
import edu.umd.cs.findbugs.bcel.OpcodeStackDetector;
/**
* if we get from a ConcurrentHashMap and assign to a variable... and don't do
* anything else and perform a null check on it... and then do a set on it...
* (or anything else inside the if that modifies it?) then we have a bug.
*
* @author Michael Midgley-Biggs
*/
public class AtomicityProblem extends OpcodeStackDetector {
int priority = IGNORE_PRIORITY;
int lastQuestionableCheckTarget = -1;
private final BugReporter bugReporter;
final static boolean DEBUG = false;
public AtomicityProblem(BugReporter bugReporter) {
this.bugReporter = bugReporter;
}
@Override
public void visit(Code obj) {
if (DEBUG) {
System.out.println("Checking " + obj);
}
lastQuestionableCheckTarget = -1;
super.visit(obj);
}
/**
* This is the "dumb" version of the detector. It may generate false
* positives, and/or not detect all instances of the bug.
*
* @see edu.umd.cs.findbugs.visitclass.DismantleBytecode#sawOpcode(int)
*/
@Override
public void sawOpcode(int seen) {
if (DEBUG) {
System.out.println(getPC() + " " + OPCODE_NAMES[seen]);
}
switch (seen) {
case IFNE:
case IFEQ: {
OpcodeStack.Item top = stack.getStackItem(0);
if (DEBUG) {
System.out.println("Stack top: " + top);
}
XMethod m = top.getReturnValueOf();
if (m != null && m.getClassName().equals("java.util.concurrent.ConcurrentHashMap")
&& m.getName().equals("containsKey")) {
lastQuestionableCheckTarget = getBranchTarget();
if (seen == IFEQ) {
priority = LOW_PRIORITY;
} else if (seen == IFNE) {
priority = NORMAL_PRIORITY;
}
}
break;
}
case IFNULL:
case IFNONNULL: {
OpcodeStack.Item top = stack.getStackItem(0);
if (DEBUG) {
System.out.println("Stack top: " + top);
}
XMethod m = top.getReturnValueOf();
if (DEBUG) {
System.out.println("Found null check");
}
if (m != null && m.getClassName().equals("java.util.concurrent.ConcurrentHashMap") && m.getName().equals("get")) {
lastQuestionableCheckTarget = getBranchTarget();
if (seen == IFNULL) {
priority = LOW_PRIORITY;
} else if (seen == IFNONNULL) {
priority = NORMAL_PRIORITY;
}
}
break;
}
case INVOKEVIRTUAL:
case INVOKEINTERFACE: {
if (getDottedClassConstantOperand().equals("java.util.concurrent.ConcurrentHashMap")) {
String methodName = getNameConstantOperand();
XClass xClass = getXClassOperand();
if (xClass != null && methodName.equals("put")) {
if ((getPC() < lastQuestionableCheckTarget) && (lastQuestionableCheckTarget != -1)) {
bugReporter.reportBug(new BugInstance(this, "AT_OPERATION_SEQUENCE_ON_CONCURRENT_ABSTRACTION", priority)
.addClassAndMethod(this).addType(xClass.getClassDescriptor()).addCalledMethod(this)
.addSourceLine(this));
}
}
}
break;
}
default:
break;
}
}
}