Add gcStats system primitive (#35)

src/som/primitives/SystemPrimitives.java

@@ -25,15 +25,20 @@
 package som.primitives;
 
 import java.io.IOException;
+import java.lang.management.GarbageCollectorMXBean;
+import java.lang.management.ManagementFactory;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.List;
 
+import com.sun.management.ThreadMXBean;
 import som.compiler.ProgramDefinitionError;
 import som.interpreter.Frame;
 import som.interpreter.Interpreter;
 import som.vm.Universe;
 import som.vmobjects.SAbstractObject;
+import som.vmobjects.SArray;
 import som.vmobjects.SClass;
 import som.vmobjects.SInteger;
 import som.vmobjects.SPrimitive;
@@ -162,6 +167,42 @@ public void invoke(final Frame frame, final Interpreter interpreter) {
  }
  });
 
+ installInstancePrimitive(new SPrimitive("gcStats", universe) {
+
+ @Override
+ public void invoke(Frame frame, Interpreter interpreter) {
+ frame.pop();
+
+ final List<GarbageCollectorMXBean> gcBeans =
+ ManagementFactory.getGarbageCollectorMXBeans();
+ final ThreadMXBean threadBean = (ThreadMXBean) ManagementFactory.getThreadMXBean();
+ threadBean.setThreadAllocatedMemoryEnabled(true);
+
+ final long allocatedBytes = threadBean.getCurrentThreadAllocatedBytes();
+ long counts = 0;
+ long time = 0;
+
+ for (GarbageCollectorMXBean b : gcBeans) {
+ long c = b.getCollectionCount();
+ if (c != -1) {
+ counts += c;
+ }
+
+ long t = b.getCollectionTime();
+ if (t != -1) {
+ time += t;
+ }
+ }
+
+ final SArray arr = new SArray(universe.nilObject, 3L);
+ arr.setIndexableField(0L, SInteger.getInteger(counts));
+ arr.setIndexableField(1L, SInteger.getInteger(time));
+ arr.setIndexableField(2L, SInteger.getInteger(allocatedBytes));
+
+ frame.push(arr);
+ }
+ });
+
  installInstancePrimitive(new SPrimitive("loadFile:", universe) {
 
  @Override