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, 18 insertions, 0 deletions

diff --git a/src/node_buffer.h b/src/node_buffer.h
index ca9a135e9df..78e6e42f6cb 100644
--- a/src/node_buffer.h
+++ b/src/node_buffer.h
@@ -26,6 +26,10 @@
 #include "smalloc.h"
 #include "v8.h"
 
+#if defined(NODE_WANT_INTERNALS)
+#include "env.h"
+#endif  // defined(NODE_WANT_INTERNALS)
+
 namespace node {
 namespace Buffer {
 
@@ -56,6 +60,20 @@ NODE_EXTERN v8::Local<v8::Object> New(char* data,
 // TODO(trevnorris): should be New() for consistency
 NODE_EXTERN v8::Local<v8::Object> Use(char* data, uint32_t len);
 
+// Internal. Not for public consumption. We can't define these in
+// src/node_internals.h due to a circular dependency issue with
+// the smalloc.h and node_internals.h headers.
+#if defined(NODE_WANT_INTERNALS)
+v8::Local<v8::Object> New(Environment* env, size_t size);
+v8::Local<v8::Object> New(Environment* env, const char* data, size_t len);
+v8::Local<v8::Object> New(Environment* env,
+                          char* data,
+                          size_t length,
+                          smalloc::FreeCallback callback,
+                          void* hint);
+v8::Local<v8::Object> Use(Environment* env, char* data, uint32_t length);
+#endif  // defined(NODE_WANT_INTERNALS)
+
 }  // namespace Buffer
 }  // namespace node