implement weak reference callbacks in handles.

ext/v8/v8_handle.cpp

@@ -4,15 +4,29 @@
 
 using namespace v8;
 
-v8_handle::v8_handle(Handle<void> handle) : handle(Persistent<void>::New(handle)) {}
+v8_handle::v8_handle(Handle<void> handle) : handle(Persistent<void>::New(handle)) {
+  this->references = rb_hash_new();
+  this->dead = false;
+}
 
 v8_handle::~v8_handle() {
   handle.Dispose();
   handle.Clear();
+  dead = true;
+}
+
+void v8_handle::set_internal(const char* name, VALUE value) {
+  rb_hash_aset(this->references, rb_str_new2(name), value);
+}
+
+VALUE v8_handle::get_internal(const char* name) {
+  return rb_funcall(this->references, rb_intern("[]"), 1, rb_str_new2(name));
 }
 
 namespace {
-  void gc_mark(v8_handle* handle) {}
+  void gc_mark(v8_handle* handle) {
+    rb_gc_mark(handle->references);
+  }
 
   void gc_free(v8_handle* handle) {
     delete handle;
@@ -41,10 +55,22 @@ namespace {
     return Qnil;
   }
 
-  void NoopWeakReferenceCallback(Persistent<Value> object, void* parameter) {}
+  void RubyWeakReferenceCallback(Persistent<Value> value, void* parameter) {
+    value.Dispose();
+    v8_handle* handle = rr_v8_handle_raw((VALUE)parameter);
+    handle->handle.Dispose();
+    handle->handle.Clear();
+    handle->dead = true;
+    VALUE callback = rr_v8_handle_get_internal((VALUE)parameter, "weakref_callback");
+    if (RTEST(callback)) {
+      rb_funcall(callback, rb_intern("call"), 0);
+    }
+  }
+
 
   VALUE MakeWeak(VALUE self) {
-    rr_v8_handle<void>(self).MakeWeak(0, NoopWeakReferenceCallback);
+    rr_v8_handle_set_internal(self,"weakref_callback", rb_block_proc());
+    rr_v8_handle<void>(self).MakeWeak((void*)self, RubyWeakReferenceCallback);
     return Qnil;
   }
 
@@ -57,6 +83,10 @@ namespace {
     return rr_v82rb(rr_v8_handle<void>(self).IsNearDeath());
   }
 
+  VALUE IsDead(VALUE self) {
+    return rr_v82rb(rr_v8_handle_raw(self)->dead);
+  }
+
   VALUE IsWeak(VALUE self) {
     return rr_v82rb(rr_v8_handle<void>(self).IsWeak());
   }
@@ -71,6 +101,7 @@ void rr_init_handle() {
   rr_define_method(HandleClass, "MakeWeak", MakeWeak, 0);
   rr_define_method(HandleClass, "ClearWeak", ClearWeak, 0);
   rr_define_method(HandleClass, "IsNearDeath", IsNearDeath, 0);
+  rr_define_method(HandleClass, "IsDead", IsDead, 0);
   rr_define_method(HandleClass, "IsWeak", IsWeak, 0);
 }
 
@@ -82,3 +113,17 @@ VALUE rr_v8_handle_class() {
   return rr_define_class("Handle");
 }
 
+void rr_v8_handle_set_internal(VALUE handle, const char* name, VALUE value) {
+  rr_v8_handle_raw(handle)->set_internal(name, value);
+}
+
+VALUE rr_v8_handle_get_internal(VALUE handle, const char* name) {
+  return rr_v8_handle_raw(handle)->get_internal(name);
+}
+
+v8_handle* rr_v8_handle_raw(VALUE value) {
+  v8_handle* handle = 0;
+  Data_Get_Struct(value, struct v8_handle, handle);
+  return handle;
+}
+

ext/v8/v8_handle.h

@@ -7,17 +7,26 @@
 struct v8_handle  {
   v8_handle(v8::Handle<void> object);
   virtual ~v8_handle();
+  VALUE get_internal(const char* name);
+  void set_internal(const char* name, VALUE value);
+
   v8::Persistent<void> handle;
+  bool dead;
+  VALUE references;
 };
 
 void rr_init_handle();
 
+v8_handle* rr_v8_handle_raw(VALUE value);
+
 template <class T> v8::Persistent<T>& rr_v8_handle(VALUE value) {
-  v8_handle* handle = 0;
-  Data_Get_Struct(value, struct v8_handle, handle);
-  return (v8::Persistent<T>&)handle->handle;
+  return (v8::Persistent<T>&)(rr_v8_handle_raw(value)->handle);
 }
 VALUE rr_v8_handle_new(VALUE rbclass, v8::Handle<void> handle);
 VALUE rr_v8_handle_class();
 
+void rr_v8_handle_set_internal(VALUE handle, const char* name, VALUE value);
+VALUE rr_v8_handle_get_internal(VALUE handle, const char* name);
+
+
 #endif

spec/ext/mem_spec.rb

@@ -0,0 +1,54 @@
+
+require 'spec_helper'
+
+describe "Memory:" do
+  context "A JavaScript Object reflected into ruby" do
+    before(:all) {c::V8::SetFlagsFromString("--expose-gc")}
+    before do
+      @cxt = c::Context::New()
+      @cxt.Enter()
+    end
+    
+    after do
+      @cxt.Exit()
+    end
+
+    it "has a strong reference from the ruby side" do
+      handle = c::Handle::New(object = c::Object::New())
+      collected = false
+      handle.MakeWeak() {collected = true; puts "yo"}
+      v8_gc
+      collected.should_not be_true
+      handle.IsDead().should be_false
+    end
+    
+    it "will be garbarge collected if there are no more ruby references and is weakly reachable from V8" do
+      handle = c::Handle::New(object = c::Object::New())
+      object = nil
+      collected = false
+      handle.MakeWeak() {collected = true}
+      ruby_gc do
+        v8_gc
+        collected.should be_true
+        handle.IsDead().should be_true
+      end
+    end
+    
+    private 
+
+    def v8_gc
+      c::Script::New(c::String::New("gc()"), c::String::New("gc.js")).Run()
+    end
+    
+    def ruby_gc
+      GC.stress = true
+      yield if block_given?
+    ensure
+      GC.stress = false
+    end
+    
+    def c
+      V8::C
+    end
+  end
+end