Only use a single ByteClassLoader, attached to the GlobalContext.

In a few cases (Java interop), we still have to create additional
ByteClassLoaders, but this should cut down memory use a bit.

Author: arnsholt

src/vm/jvm/runtime/org/perl6/nqp/runtime/BootJavaInterop.java

@@ -222,10 +222,13 @@ protected void finishClass(ClassContext cc) {
         //} catch (java.io.IOException e) {
         //    e.printStackTrace();
         //}
-        cc.constructed = (cc.target == null
-                ? new ByteClassLoader(bits)
-                : new ByteClassLoader(bits, cc.target.getClassLoader())
-            ).findClass(cc.className.replace('/','.'));
+        // XXX: The condition here can probably cut down a few more
+        // allocations if we check if the target's class loader isn't in the
+        // chain of loaders above gc.byteClassLoader.
+        ByteClassLoader loader = cc.target == null
+                ? gc.byteClassLoader
+                : new ByteClassLoader(cc.target.getClassLoader());
+        cc.constructed = loader.defineClass(cc.className.replace('/','.'), bits);
         try {
             cc.constructed.getField("constants").set(null, cc.constants.toArray(new Object[0]));
         } catch (ReflectiveOperationException roe) {

src/vm/jvm/runtime/org/perl6/nqp/runtime/ByteClassLoader.java

@@ -1,18 +1,15 @@
 package org.perl6.nqp.runtime;
 
 public class ByteClassLoader extends ClassLoader {
-    private byte[] bytes;
-    
-    public ByteClassLoader(byte[] bytes) {
-        this.bytes = bytes;
+    public ByteClassLoader() {
+        super();
     }
-    
-    public ByteClassLoader(byte[] bytes, ClassLoader parent) {
+
+    public ByteClassLoader(ClassLoader parent) {
         super(parent);
-        this.bytes = bytes;
     }
-    
-    public Class<?> findClass(String name) {
-        return defineClass(name, this.bytes, 0, this.bytes.length);
+
+    public Class<?> defineClass(String name, byte[] bytes) {
+        return defineClass(name, bytes, 0, bytes.length);
     }
 }

src/vm/jvm/runtime/org/perl6/nqp/runtime/GlobalContext.java

@@ -168,6 +168,12 @@ public class GlobalContext {
      */
     public boolean noisyExceptions;
 
+    /**
+     * The global ByteClassLoader instance, used to load classes generated at
+     * runtime.
+     */
+    public ByteClassLoader byteClassLoader;
+
     /** Redirected output for eval-server. */
     public PrintStream out = System.out;
     /** Redirected error for eval-server. */
@@ -231,6 +237,8 @@ public GlobalContext()
 
         hllGlobalAll = new HashMap<ContextKey<?,?>, Object>();
         hllGlobalAllLock = new Object();
+
+        byteClassLoader = new ByteClassLoader();
     }
 
     /**

src/vm/jvm/runtime/org/perl6/nqp/runtime/Ops.java

@@ -5202,8 +5202,8 @@ public static SixModelObject compilejastlinestofile(SixModelObject dump, String
     public static SixModelObject loadcompunit(SixModelObject obj, long compileeHLL, ThreadContext tc) {
         try {
             EvalResult res = (EvalResult)obj;
-            ByteClassLoader cl = new ByteClassLoader(res.jc.bytes);
-            res.cu = (CompilationUnit)cl.findClass(res.jc.name).newInstance();
+            Class<?> cuClass = tc.gc.byteClassLoader.defineClass(res.jc.name, res.jc.bytes);
+            res.cu = (CompilationUnit) cuClass.newInstance();
             if (compileeHLL != 0)
                 usecompileehllconfig(tc);
             res.cu.initializeCompilationUnit(tc);

src/vm/jvm/runtime/org/perl6/nqp/sixmodel/ByteClassLoader.java

@@ -11,7 +11,6 @@
 import org.objectweb.asm.Opcodes;
 import org.objectweb.asm.Type;
 
-import org.perl6.nqp.sixmodel.ByteClassLoader;
 import org.perl6.nqp.sixmodel.REPR;
 import org.perl6.nqp.sixmodel.SerializationReader;
 import org.perl6.nqp.sixmodel.SixModelObject;
@@ -103,7 +102,6 @@ public void deserialize_finish(ThreadContext tc, STable st, SerializationReader
     }
 
     private static long typeId = 0;
-    private static ByteClassLoader loader = new ByteClassLoader();
     private void generateStructClass(ThreadContext tc, STable st, List<AttrInfo> fields) {
         CStructREPRData reprData = (CStructREPRData) st.REPRData;
         ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES);
@@ -164,7 +162,7 @@ private void generateStructClass(ThreadContext tc, STable st, List<AttrInfo> fie
 
         cw.visitEnd();
         byte[] compiled = cw.toByteArray();
-        reprData.structureClass = loader.defineClass(className, compiled);
+        reprData.structureClass = tc.gc.byteClassLoader.defineClass(className, compiled);
     }
 
     private String typeDescriptor(ThreadContext tc, AttrInfo info) {

src/vm/jvm/runtime/org/perl6/nqp/sixmodel/reprs/CStruct.java

@@ -14,7 +14,6 @@
 import org.objectweb.asm.Type;
 import org.perl6.nqp.runtime.ExceptionHandling;
 import org.perl6.nqp.runtime.ThreadContext;
-import org.perl6.nqp.sixmodel.ByteClassLoader;
 import org.perl6.nqp.sixmodel.REPR;
 import org.perl6.nqp.sixmodel.STable;
 import org.perl6.nqp.sixmodel.SerializationReader;
@@ -25,7 +24,6 @@
 
 public class P6Opaque extends REPR {
     private static long typeId = 0;
-    private static ByteClassLoader loader = new ByteClassLoader();
 
     private static class AttrInfo {
         public STable st;
@@ -625,7 +623,7 @@ private Class<?> generateJVMClass(ThreadContext tc, List<AttrInfo> attrInfoList)
 //            fos.close();
 //        } catch (IOException e) {
 //        }
-        return loader.defineClass(className, classCompiled);
+        return tc.gc.byteClassLoader.defineClass(className, classCompiled);
     }
 
     private void generateDelegateMethod(ThreadContext tc, ClassWriter cw, String className, String field, String methodName) {