Tweaks here and there to make procs serializable.

Caveats:

* Only interpreted procs will serialize, since compiled/jitted don't safe their bytecode.
* Wherever a class is referenced (object metaclass, const scoping) the name is stored and looked up on the other side.
* Assumes we're loading into the one global org.jruby.Ruby instance; this could be made Thread-local as well.

src/org/jruby/RubyBasicObject.java

@@ -27,6 +27,7 @@
  ***** END LICENSE BLOCK *****/
 package org.jruby;
 
+import java.io.IOException;
 import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.List;
@@ -1897,4 +1898,14 @@ private void callFinalizer(IRubyObject finalizer) {
                     finalizer, "call", id);
         }
     }
+
+    private void writeObject(java.io.ObjectOutputStream out) throws IOException {
+        out.defaultWriteObject();
+        out.writeUTF(metaClass.getName());
+    }
+
+    private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
+        in.defaultReadObject();
+        metaClass = (RubyClass)Ruby.getGlobalRuntime().getClassFromPath(in.readUTF());
+    }
 }

src/org/jruby/parser/StaticScope.java

@@ -483,4 +483,21 @@ public String toString() {
 
         return buf.toString();
     }
+
+    private void writeObject(java.io.ObjectOutputStream out) throws IOException {
+        out.defaultWriteObject();
+        if (cref != null) {
+            out.writeObject(cref.getName());
+        } else {
+            out.writeObject(null);
+        }
+    }
+
+    private void readObject(java.io.ObjectInputStream in) throws IOException, ClassNotFoundException {
+        in.defaultReadObject();
+        Object crefName = in.readObject();
+        if (crefName != null) {
+            cref = Ruby.getGlobalRuntime().getClassFromPath(crefName.toString());
+        }
+    }
 }

src/org/jruby/runtime/Binding.java

@@ -32,20 +32,21 @@
  ***** END LICENSE BLOCK *****/
 package org.jruby.runtime;
 
+import java.io.Serializable;
 import org.jruby.RubyModule;
 import org.jruby.parser.StaticScope;
 import org.jruby.runtime.builtin.IRubyObject;
 
 /**
  *  Internal live representation of a block ({...} or do ... end).
  */
-public class Binding {
+public class Binding implements Serializable {
 
     /**
      * frame of method which defined this block
      */
     private final Frame frame;
-    private final RubyModule klass;
+    private transient final RubyModule klass;
 
     private Visibility visibility;
     /**

src/org/jruby/runtime/Block.java

@@ -41,14 +41,15 @@
 
 package org.jruby.runtime;
 
+import java.io.Serializable;
 import org.jruby.RubyModule;
 import org.jruby.RubyProc;
 import org.jruby.runtime.builtin.IRubyObject;
 
 /**
  *  Internal live representation of a block ({...} or do ... end).
  */
-public final class Block {
+public final class Block implements Serializable {
     public enum Type { NORMAL, PROC, LAMBDA, THREAD }
 
     /**

src/org/jruby/runtime/BlockBody.java

@@ -41,6 +41,7 @@
 
 package org.jruby.runtime;
 
+import java.io.Serializable;
 import org.jruby.RubyArray;
 import org.jruby.RubyModule;
 import org.jruby.ast.IterNode;
@@ -53,7 +54,7 @@
 /**
  * The executable body portion of a closure.
  */
-public abstract class BlockBody {
+public abstract class BlockBody implements Serializable {
     // FIXME: Maybe not best place, but move it to a good home
     public static final int ZERO_ARGS = 0;
     public static final int MULTIPLE_ASSIGNMENT = 1;

src/org/jruby/runtime/DynamicScope.java

@@ -8,6 +8,7 @@
 
 package org.jruby.runtime;
 
+import java.io.Serializable;
 import org.jruby.Ruby;
 import org.jruby.parser.BlockStaticScope;
 import org.jruby.runtime.scope.ManyVarsDynamicScope;
@@ -21,7 +22,7 @@
 import org.jruby.runtime.scope.ThreeVarDynamicScope;
 import org.jruby.runtime.scope.TwoVarDynamicScope;
 
-public abstract class DynamicScope {
+public abstract class DynamicScope implements Serializable {
     // Static scoping information for this scope
     protected final StaticScope staticScope;
 

src/org/jruby/runtime/Frame.java

@@ -32,6 +32,7 @@
  ***** END LICENSE BLOCK *****/
 package org.jruby.runtime;
 
+import java.io.Serializable;
 import org.jruby.RubyModule;
 import org.jruby.runtime.builtin.IRubyObject;
 
@@ -60,9 +61,9 @@
  * 
  * @see ThreadContext
  */
-public final class Frame {
+public final class Frame implements Serializable {
     /** The class against which this call is executing. */
-    private RubyModule klazz;
+    private transient RubyModule klazz;
 
     /** The 'self' for this frame. */
     private IRubyObject self;

src/org/jruby/runtime/InterpretedBlock.java

@@ -32,6 +32,7 @@
  ***** END LICENSE BLOCK *****/
 package org.jruby.runtime;
 
+import java.io.Serializable;
 import org.jruby.Ruby;
 import org.jruby.RubyModule;
 import org.jruby.ast.IterNode;
@@ -76,7 +77,7 @@
  * 
  * @see SharedScopeBlock, CompiledBlock
  */
-public class InterpretedBlock extends BlockBody {
+public class InterpretedBlock extends BlockBody implements Serializable {
     /** This block has no arguments at all (simple secondary optimization @see assignerFor for an
      * explanation).
      */

src/org/jruby/runtime/assigner/Assigner.java

@@ -29,6 +29,7 @@
 
 package org.jruby.runtime.assigner;
 
+import java.io.Serializable;
 import org.jruby.Ruby;
 import org.jruby.ast.util.ArgsUtil;
 import org.jruby.runtime.Block;
@@ -50,7 +51,7 @@
  * There is also some logic about expanded/non-expanded arguments.  This refers to
  * ParserSupport.new_yield and YieldNode expanded attribute.
  */
-public abstract class Assigner {
+public abstract class Assigner implements Serializable {
 
     public abstract void assign(Ruby runtime, ThreadContext context, IRubyObject self, Block block);
     public abstract void assign(Ruby runtime, ThreadContext context, IRubyObject self, IRubyObject value1,