src: make BaseObject iteration order deterministic

Previously we just rely on the unordered_set order to iterate over
the BaseObjects, which is not deterministic.

The iteration is only used in printing, verification, and snapshot
generation. In the first two cases the performance overhead of
sorting does not matter because they are only used for debugging.
In the last case the determinism is more important than the trivial
overhead of sorting. So this patch makes the iteration deterministic
by sorting the set first, as what is already being done when we
drain the queue.

PR-URL: #48702
Refs: nodejs/build#3043
Reviewed-By: Tobias Nießen <[email protected]>
Reviewed-By: Yagiz Nizipli <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>

Author: joyeecheung

src/cleanup_queue-inl.h

@@ -39,7 +39,9 @@ void CleanupQueue::Remove(Callback cb, void* arg) {
 
 template <typename T>
 void CleanupQueue::ForEachBaseObject(T&& iterator) const {
-  for (const auto& hook : cleanup_hooks_) {
+  std::vector<CleanupHookCallback> callbacks = GetOrdered();
+
+  for (const auto& hook : callbacks) {
     BaseObject* obj = GetBaseObject(hook);
     if (obj != nullptr) iterator(obj);
   }

src/cleanup_queue.cc

@@ -5,7 +5,8 @@
 
 namespace node {
 
-void CleanupQueue::Drain() {
+std::vector<CleanupQueue::CleanupHookCallback> CleanupQueue::GetOrdered()
+    const {
   // Copy into a vector, since we can't sort an unordered_set in-place.
   std::vector<CleanupHookCallback> callbacks(cleanup_hooks_.begin(),
                                              cleanup_hooks_.end());
@@ -20,6 +21,12 @@ void CleanupQueue::Drain() {
               return a.insertion_order_counter_ > b.insertion_order_counter_;
             });
 
+  return callbacks;
+}
+
+void CleanupQueue::Drain() {
+  std::vector<CleanupHookCallback> callbacks = GetOrdered();
+
   for (const CleanupHookCallback& cb : callbacks) {
     if (cleanup_hooks_.count(cb) == 0) {
       // This hook was removed from the `cleanup_hooks_` set during another

src/cleanup_queue.h

@@ -6,6 +6,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <unordered_set>
+#include <vector>
 
 #include "memory_tracker.h"
 
@@ -66,6 +67,7 @@ class CleanupQueue : public MemoryRetainer {
     uint64_t insertion_order_counter_;
   };
 
+  std::vector<CleanupHookCallback> GetOrdered() const;
   inline BaseObject* GetBaseObject(const CleanupHookCallback& callback) const;
 
   // Use an unordered_set, so that we have efficient insertion and removal.