Use a soft-value cache in the class repository, this resolves the memory-leaking issues that the original repository has.

Author: Kiskae

src/main/java/nl/rug/jbi/jsm/core/JSMCore.java

@@ -1,7 +1,7 @@
 package nl.rug.jbi.jsm.core;
 
 import com.google.common.base.Preconditions;
-import nl.rug.jbi.jsm.bcel.CompositeBCELClassLoader;
+import nl.rug.jbi.jsm.util.CompositeBCELClassLoader;
 import nl.rug.jbi.jsm.core.calculator.BaseMetric;
 import nl.rug.jbi.jsm.core.calculator.MetricCollection;
 import nl.rug.jbi.jsm.core.calculator.MetricScope;

src/main/java/nl/rug/jbi/jsm/core/execution/ControllerThread.java

@@ -215,6 +215,7 @@ public void run() {
         }
 
         executorPool.shutdown();
+        repo.clear();
 
         executionPlan.onFinish();
     }

src/main/java/nl/rug/jbi/jsm/core/execution/PipelineExecutor.java

@@ -1,14 +1,14 @@
 package nl.rug.jbi.jsm.core.execution;
 
 import com.google.common.base.Preconditions;
-import nl.rug.jbi.jsm.bcel.CompositeBCELClassLoader;
 import nl.rug.jbi.jsm.core.calculator.MetricResult;
 import nl.rug.jbi.jsm.core.calculator.MetricScope;
 import nl.rug.jbi.jsm.core.pipeline.HandlerMap;
 import nl.rug.jbi.jsm.core.pipeline.Pipeline;
 import nl.rug.jbi.jsm.core.pipeline.PipelineFrame;
 import nl.rug.jbi.jsm.frontend.Frontend;
-import org.apache.bcel.util.ClassLoaderRepository;
+import nl.rug.jbi.jsm.util.CompositeBCELClassLoader;
+import nl.rug.jbi.jsm.util.SoftValueClassLoaderRepository;
 import org.apache.bcel.util.Repository;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
@@ -53,7 +53,7 @@ public PipelineExecutor(
             final ClassVisitorFactory cvFactory) {
         this.frontend = frontend;
         this.dataSource = dataSource;
-        this.repo = new ClassLoaderRepository(dataSource);
+        this.repo = new SoftValueClassLoaderRepository(dataSource);
         this.handlerMap = executionPlan.getHandlerMaps();
         this.frameMap = executionPlan.getPipelineFrames();
         this.cvFactory = cvFactory;

src/main/java/nl/rug/jbi/jsm/metrics/ClassSourceProducer.java

@@ -2,7 +2,7 @@
 
 import com.google.common.base.Supplier;
 import com.google.common.collect.Lists;
-import nl.rug.jbi.jsm.bcel.CompositeBCELClassLoader;
+import nl.rug.jbi.jsm.util.CompositeBCELClassLoader;
 import nl.rug.jbi.jsm.bcel.JavaClassDefinition;
 import nl.rug.jbi.jsm.core.calculator.MetricScope;
 import nl.rug.jbi.jsm.core.calculator.MetricState;

…i/jsm/bcel/CompositeBCELClassLoader.java …i/jsm/util/CompositeBCELClassLoader.javasrc/main/java/nl/rug/jbi/jsm/bcel/CompositeBCELClassLoader.java renamed to src/main/java/nl/rug/jbi/jsm/util/CompositeBCELClassLoader.java src/main/java/nl/rug/jbi/jsm/bcel/CompositeBCELClassLoader.java renamed to src/main/java/nl/rug/jbi/jsm/util/CompositeBCELClassLoader.java

@@ -1,4 +1,4 @@
-package nl.rug.jbi.jsm.bcel;
+package nl.rug.jbi.jsm.util;
 
 import com.google.common.base.Preconditions;
 import com.google.common.collect.Lists;

src/main/java/nl/rug/jbi/jsm/util/SoftValueClassLoaderRepository.java

@@ -0,0 +1,53 @@
+package nl.rug.jbi.jsm.util;
+
+import com.google.common.cache.Cache;
+import com.google.common.cache.CacheBuilder;
+import org.apache.bcel.classfile.JavaClass;
+import org.apache.bcel.util.ClassLoaderRepository;
+
+/**
+ * Extended version of the default BCEL {@link org.apache.bcel.util.ClassLoaderRepository}.
+ * <br>
+ * The original version uses a hash map to store the previously loaded classes, this creates a java memory leak for
+ * larger inspections, since those classes never get released during execution.
+ * <br>
+ * This implementation uses Guava's {@link com.google.common.cache.Cache} with soft-reference values so the JVM can
+ * reclaim memory if it needs to, at the expense of slightly increasing class lookup time through this class.
+ *
+ * @author David van Leusen
+ * @since 2014-07-14
+ */
+public class SoftValueClassLoaderRepository extends ClassLoaderRepository {
+    private final Cache<String, JavaClass> classCache = CacheBuilder.newBuilder()
+            .softValues()
+            .build();
+
+    /**
+     * @param loader The class loader from which to load class-data.
+     */
+    public SoftValueClassLoaderRepository(final ClassLoader loader) {
+        super(loader);
+        super.clear();
+    }
+
+    @Override
+    public void storeClass(JavaClass clazz) {
+        classCache.put(clazz.getClassName(), clazz);
+        clazz.setRepository(this);
+    }
+
+    @Override
+    public void removeClass(JavaClass clazz) {
+        classCache.invalidate(clazz.getClassName());
+    }
+
+    @Override
+    public JavaClass findClass(String className) {
+        return classCache.getIfPresent(className);
+    }
+
+    @Override
+    public void clear() {
+        classCache.invalidateAll();
+    }
+}