src: add consistency check to node_platform.cc

We use the `Isolate*` pointer as the sole identifier
for a V8 Isolate. In some environments (e.g. multi-threaded),
Isolates may be destroyed and new ones created; then, it
may happen that the memory that was previously used for
one `Isolate` can be re-used for another `Isolate`
after the first one has been disposed of.

This check is a little guard against accidentally
re-using the same per-Isolate platform data structure
in such cases, i.e. making sure (to the degree to which
that is possible) that the old `Isolate*` has been properly
unregistered before one at the same memory address is added.

(It’s not 100 % foolproof because the `uv_loop_t*`
pointer value could theoretically be the same as well.)

PR-URL: https://github.com/nodejs/node/pull/21156
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/node_platform.h b/src/node_platform.h
index cf0809ad1f..f6a177c924 100644
--- a/src/node_platform.h
+++ b/src/node_platform.h
@@ -72,6 +72,8 @@ class PerIsolatePlatformData :
   bool FlushForegroundTasksInternal();
   void CancelPendingDelayedTasks();
 
+  const uv_loop_t* event_loop() const { return loop_; }
+
  private:
   void DeleteFromScheduledTasks(DelayedTask* task);