src: add multi-context support

This commit makes it possible to use multiple V8 execution contexts
within a single event loop.  Put another way, handle and request wrap
objects now "remember" the context they belong to and switch back to
that context when the time comes to call into JS land.

This could have been done in a quick and hacky way by calling
v8::Object::GetCreationContext() on the wrap object right before
making a callback but that leaves a fairly wide margin for bugs.

Instead, we make the context explicit through a new Environment class
that encapsulates everything (or almost everything) that belongs to
the context.  Variables that used to be a static or a global are now
members of the aforementioned class.  An additional benefit is that
this approach should make it relatively straightforward to add full
isolate support in due course.

There is no JavaScript API yet but that will be added in the near
future.

This work was graciously sponsored by GitHub, Inc.

1 files changed, 9 insertions, 5 deletions

diff --git a/src/udp_wrap.h b/src/udp_wrap.h
index e0cfc7ba264..b9aa566be22 100644
--- a/src/udp_wrap.h
+++ b/src/udp_wrap.h
@@ -22,15 +22,19 @@
 #ifndef SRC_UDP_WRAP_H_
 #define SRC_UDP_WRAP_H_
 
-#include "node.h"
-#include "req_wrap.h"
+#include "env.h"
 #include "handle_wrap.h"
+#include "req_wrap.h"
+#include "uv.h"
+#include "v8.h"
 
 namespace node {
 
 class UDPWrap: public HandleWrap {
  public:
-  static void Initialize(v8::Handle<v8::Object> target);
+  static void Initialize(v8::Handle<v8::Object> target,
+                         v8::Handle<v8::Value> unused,
+                         v8::Handle<v8::Context> context);
   static void GetFD(v8::Local<v8::String>,
                     const v8::PropertyCallbackInfo<v8::Value>&);
   static void New(const v8::FunctionCallbackInfo<v8::Value>& args);
@@ -50,11 +54,11 @@ class UDPWrap: public HandleWrap {
   static void SetTTL(const v8::FunctionCallbackInfo<v8::Value>& args);
   static UDPWrap* Unwrap(v8::Local<v8::Object> obj);
 
-  static v8::Local<v8::Object> Instantiate();
+  static v8::Local<v8::Object> Instantiate(Environment* env);
   uv_udp_t* UVHandle();
 
  private:
-  explicit UDPWrap(v8::Handle<v8::Object> object);
+  UDPWrap(Environment* env, v8::Handle<v8::Object> object);
   virtual ~UDPWrap();
 
   static void DoBind(const v8::FunctionCallbackInfo<v8::Value>& args,