Fix library private key stability during reload

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index 5003e7e1123010340703167e50e3252ce2356933..9b59bcb80b9f43accbde84511898107e10f4da56 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -10551,6 +10551,18 @@ void Library::AllocatePrivateKey() const {
   Zone* zone = thread->zone();
   Isolate* isolate = thread->isolate();
 
+  if (isolate->IsReloading()) {
+    // When reloading, we need to make sure we use the original private key
+    // if this library previously existed.
+    IsolateReloadContext* reload_context = isolate->reload_context();
+    const String& original_key =
+        String::Handle(reload_context->FindLibraryPrivateKey(*this));
+    if (!original_key.IsNull()) {
+      StorePointer(&raw_ptr()->private_key_, original_key.raw());

[siva, 2016/06/13 19:49:56]

How do you ensure that there is no collision between the original_key and any
new key that is computed for say a new library that got added as part of the
reload?

[Cutch, 2016/06/13 19:55:38]

Presently we don't. I wonder if we should go back to the old way of assigning
library private keys when reloading?

+      return;
+    }
+  }
+
   // Format of the private key is: "@<sequence number><6 digits of hash>
   const intptr_t hash_mask = 0x7FFFF;