async_wrap,src: add GetAsyncId() method

Allow handles to retrieve their own uid's by adding a new method on the
FunctionTemplates. Implementation of these into all other classes will
come in a future commit.

Add the method AsyncWrap::GetAsyncId() to all inheriting class objects
so the uid of the handle can be retrieved from JS.

In all applicable locations, run ClearWrap() on the object holding the
pointer so that it never points to invalid memory and make sure Wrap()
is always run so the class pointer is correctly attached to the object
and can be retrieved so GetAsyncId() can be run.

In many places a class instance was not removing its own pointer from
object() in the destructor. This left an invalid pointer in the JS
object that could cause the application to segfault under certain
conditions.

Remove ClearWrap() from ReqWrap for continuity. The ReqWrap constructor
was not the one to call Wrap(), so it shouldn't be the one to call
ClearWrap().

Wrap() has been added to all constructors that inherit from AsyncWrap.
Normally it's the child most class. Except in the case of HandleWrap.
Which must be the constructor that runs Wrap() because the class pointer
is retrieved for certain calls and because other child classes have
multiple inheritance to pointer to the HandleWrap needs to be stored.

ClearWrap() has been placed in all FunctionTemplate constructors so that
no random values are returned when running getAsyncId(). ClearWrap() has
also been placed in all class destructors, except in those that use
MakeWeak() because the destructor will run during GC. Making the
object() inaccessible.

It could be simplified to where AsyncWrap sets the internal pointer,
then if an inheriting class needs one of it's own it could set it again.
But the inverse would need to be true also, where AsyncWrap then also
runs ClearWeak. Unforunately because some of the handles are cleaned up
during GC that's impossible. Also in the case of ReqWrap it runs Reset()
in the destructor, making the object() inaccessible. Meaning,
ClearWrap() must be run by the class that runs Wrap(). There's currently
no generalized way of taking care of this across all instances of
AsyncWrap.

I'd prefer that there be checks in there for these things, but haven't
found a way to place them that wouldn't be just as unreliable.

Add test that checks all resources that can run getAsyncId(). Would like
a way to enforce that any new classes that can also run getAsyncId() are
tested, but don't have one.

PR-URL: https://github.com/nodejs/node/pull/12892
Ref: https://github.com/nodejs/node/pull/11883
Ref: https://github.com/nodejs/node/pull/8531
Reviewed-By: Andreas Madsen <amwebdk@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/tty_wrap.cc b/src/tty_wrap.cc
index b6e3efcc10..f3f1edfe5d 100644
--- a/src/tty_wrap.cc
+++ b/src/tty_wrap.cc
@@ -53,6 +53,8 @@ void TTYWrap::Initialize(Local<Object> target,
   t->SetClassName(FIXED_ONE_BYTE_STRING(env->isolate(), "TTY"));
   t->InstanceTemplate()->SetInternalFieldCount(1);
 
+  env->SetProtoMethod(t, "getAsyncId", AsyncWrap::GetAsyncId);
+
   env->SetProtoMethod(t, "close", HandleWrap::Close);
   env->SetProtoMethod(t, "unref", HandleWrap::Unref);
   env->SetProtoMethod(t, "ref", HandleWrap::Ref);