/*
* FindBugs - Find bugs in Java programs
* Copyright (C) 2003-2005 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 java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import org.apache.bcel.generic.ConstantPoolGen;
import org.apache.bcel.generic.Instruction;
import org.apache.bcel.generic.InstructionHandle;
import org.apache.bcel.generic.ObjectType;
import org.apache.bcel.generic.Type;
import org.apache.bcel.generic.TypedInstruction;
import edu.umd.cs.findbugs.ResourceCollection;
import edu.umd.cs.findbugs.ba.BasicBlock;
import edu.umd.cs.findbugs.ba.DataflowAnalysisException;
import edu.umd.cs.findbugs.ba.Edge;
import edu.umd.cs.findbugs.ba.Location;
import edu.umd.cs.findbugs.ba.RepositoryLookupFailureCallback;
import edu.umd.cs.findbugs.ba.ResourceTracker;
import edu.umd.cs.findbugs.ba.ResourceValueFrame;
import edu.umd.cs.findbugs.ba.ResourceValueFrameModelingVisitor;
/**
* Resource tracker which determines where streams are created, and how they are
* used within the method.
*
* @author David Hovemeyer
*/
public class StreamResourceTracker implements ResourceTracker<Stream> {
private StreamFactory[] streamFactoryList;
private RepositoryLookupFailureCallback lookupFailureCallback;
private ResourceCollection<Stream> resourceCollection;
/**
* Map of locations where streams are opened to the actual Stream objects.
*/
private Map<Location, Stream> streamOpenLocationMap;
/**
* Set of all open locations and escapes of uninteresting streams.
*/
// private HashSet<Location> uninterestingStreamEscapeSet;
private HashSet<Stream> uninterestingStreamEscapeSet;
/**
* Set of all (potential) stream escapes.
*/
private TreeSet<StreamEscape> streamEscapeSet;
/**
* Map of individual streams to equivalence classes. Any time a stream "A"
* is wrapped with a stream "B", "A" and "B" belong to the same equivalence
* class. If any stream in an equivalence class is closed, then we consider
* all of the streams in the equivalence class as having been closed.
*/
private Map<Stream, StreamEquivalenceClass> streamEquivalenceMap;
/**
* Constructor.
*
* @param streamFactoryList
* array of StreamFactory objects which determine where streams
* are created
* @param lookupFailureCallback
* used when class hierarchy lookups fail
*/
// @SuppressWarnings("EI2")
public StreamResourceTracker(StreamFactory[] streamFactoryList, RepositoryLookupFailureCallback lookupFailureCallback) {
this.streamFactoryList = streamFactoryList;
this.lookupFailureCallback = lookupFailureCallback;
this.streamOpenLocationMap = new HashMap<Location, Stream>();
this.uninterestingStreamEscapeSet = new HashSet<Stream>();
this.streamEscapeSet = new TreeSet<StreamEscape>();
this.streamEquivalenceMap = new HashMap<Stream, StreamEquivalenceClass>();
}
/**
* Set the precomputed ResourceCollection for the method.
*/
public void setResourceCollection(ResourceCollection<Stream> resourceCollection) {
this.resourceCollection = resourceCollection;
}
/**
* Indicate that a stream escapes at the given target Location.
*
* @param source
* the Stream that is escaping
* @param target
* the target Location (where the stream escapes)
*/
public void addStreamEscape(Stream source, Location target) {
StreamEscape streamEscape = new StreamEscape(source, target);
streamEscapeSet.add(streamEscape);
if (FindOpenStream.DEBUG)
System.out.println("Adding potential stream escape " + streamEscape);
}
/**
* Transitively mark all streams into which uninteresting streams (such as
* System.out) escape. This handles the rule that wrapping an uninteresting
* stream makes the wrapper uninteresting as well.
*/
public void markTransitiveUninterestingStreamEscapes() {
// Eliminate all stream escapes where the target isn't really
// a stream open location point.
for (Iterator<StreamEscape> i = streamEscapeSet.iterator(); i.hasNext();) {
StreamEscape streamEscape = i.next();
if (!isStreamOpenLocation(streamEscape.target)) {
if (FindOpenStream.DEBUG)
System.out.println("Eliminating false stream escape " + streamEscape);
i.remove();
}
}
// Build initial stream equivalence classes.
// Each stream starts out in its own separate
// equivalence class.
for (Iterator<Stream> i = resourceCollection.resourceIterator(); i.hasNext();) {
Stream stream = i.next();
StreamEquivalenceClass equivalenceClass = new StreamEquivalenceClass();
equivalenceClass.addMember(stream);
streamEquivalenceMap.put(stream, equivalenceClass);
}
// Starting with the set of uninteresting stream open location points,
// propagate all uninteresting stream escapes. Iterate until there
// is no change. This also builds the map of stream equivalence classes.
Set<Stream> orig = new HashSet<Stream>();
do {
orig.clear();
orig.addAll(uninterestingStreamEscapeSet);
for (StreamEscape streamEscape : streamEscapeSet) {
if (isUninterestingStreamEscape(streamEscape.source)) {
if (FindOpenStream.DEBUG)
System.out.println("Propagating stream escape " + streamEscape);
Stream target = streamOpenLocationMap.get(streamEscape.target);
if (target == null)
throw new IllegalStateException();
uninterestingStreamEscapeSet.add(target);
// Combine equivalence classes for source and target
StreamEquivalenceClass sourceClass = streamEquivalenceMap.get(streamEscape.source);
StreamEquivalenceClass targetClass = streamEquivalenceMap.get(target);
if (sourceClass != targetClass) {
sourceClass.addAll(targetClass);
for (Iterator<Stream> j = targetClass.memberIterator(); j.hasNext();) {
Stream stream = j.next();
streamEquivalenceMap.put(stream, sourceClass);
}
}
}
}
} while (!orig.equals(uninterestingStreamEscapeSet));
}
/**
* Determine if an uninteresting stream escapes at given location.
* markTransitiveUninterestingStreamEscapes() should be called first.
*
* @param stream
* the stream
* @return true if an uninteresting stream escapes at the location
*/
public boolean isUninterestingStreamEscape(Stream stream) {
return uninterestingStreamEscapeSet.contains(stream);
}
/**
* Indicate that a stream is constructed at this Location.
*
* @param streamOpenLocation
* the Location
* @param stream
* the Stream opened at this Location
*/
public void addStreamOpenLocation(Location streamOpenLocation, Stream stream) {
if (FindOpenStream.DEBUG)
System.out.println("Stream open location at " + streamOpenLocation);
streamOpenLocationMap.put(streamOpenLocation, stream);
if (stream.isUninteresting())
uninterestingStreamEscapeSet.add(stream);
}
/**
* Get the equivalence class for given stream. May only be called if
* markTransitiveUninterestingStreamEscapes() has been called.
*
* @param stream
* the stream
* @return the set containing the equivalence class for the given stream
*/
public StreamEquivalenceClass getStreamEquivalenceClass(Stream stream) {
return streamEquivalenceMap.get(stream);
}
/**
* Determine if given Location is a stream open location point.
*
* @param location
* the Location
*/
private boolean isStreamOpenLocation(Location location) {
return streamOpenLocationMap.get(location) != null;
}
public Stream isResourceCreation(BasicBlock basicBlock, InstructionHandle handle, ConstantPoolGen cpg) {
// Use precomputed map of Locations to Stream creations,
// if present. Note that we don't care about preexisting
// resources here.
if (resourceCollection != null)
return resourceCollection.getCreatedResource(new Location(handle, basicBlock));
Instruction ins = handle.getInstruction();
if (!(ins instanceof TypedInstruction))
return null;
Type type = ((TypedInstruction) ins).getType(cpg);
if (!(type instanceof ObjectType))
return null;
Location location = new Location(handle, basicBlock);
// All StreamFactories are given an opportunity to
// look at the location and possibly identify a created stream.
for (StreamFactory aStreamFactoryList : streamFactoryList) {
Stream stream = aStreamFactoryList.createStream(location, (ObjectType) type, cpg, lookupFailureCallback);
if (stream != null)
return stream;
}
return null;
}
public boolean isResourceOpen(BasicBlock basicBlock, InstructionHandle handle, ConstantPoolGen cpg, Stream resource,
ResourceValueFrame frame) {
return resource.isStreamOpen(basicBlock, handle, cpg, frame);
}
public boolean isResourceClose(BasicBlock basicBlock, InstructionHandle handle, ConstantPoolGen cpg, Stream resource,
ResourceValueFrame frame) {
return resource.isStreamClose(basicBlock, handle, cpg, frame, lookupFailureCallback);
}
public boolean mightCloseResource(BasicBlock basicBlock, InstructionHandle handle, ConstantPoolGen cpg)
throws DataflowAnalysisException {
return Stream.mightCloseStream(basicBlock, handle, cpg);
}
public ResourceValueFrameModelingVisitor createVisitor(Stream resource, ConstantPoolGen cpg) {
return new StreamFrameModelingVisitor(cpg, this, resource);
}
public boolean ignoreImplicitExceptions(Stream resource) {
return resource.ignoreImplicitExceptions();
}
public boolean ignoreExceptionEdge(Edge edge, Stream resource, ConstantPoolGen cpg) {
return false;
}
public boolean isParamInstance(Stream resource, int slot) {
return resource.getInstanceParam() == slot;
}
}
// vim:ts=3