From ab8da70abe85b4998bbc41c1f6107dc16f347014 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B8rgen=20Edelbo?= <jorgen.edelbo@mongodb.com>
Date: Mon, 15 May 2023 17:09:36 +0200
Subject: [PATCH] Make CollectionParent::generate_key() threadsafe

---
 src/realm/collection_parent.cpp | 4 +++-
 src/realm/collection_parent.hpp | 2 +-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/realm/collection_parent.cpp b/src/realm/collection_parent.cpp
index d4c0f05ad30..270b8eb2164 100644
--- a/src/realm/collection_parent.cpp
+++ b/src/realm/collection_parent.cpp
@@ -262,11 +262,13 @@ CollectionBasePtr CollectionParent::get_collection_ptr(ColKey col_key) const
 }
 
 
-int64_t CollectionParent::generate_key(size_t sz) const
+int64_t CollectionParent::generate_key(size_t sz)
 {
     static std::mt19937 gen32;
+    static std::mutex mutex;
 
     int64_t key;
+    const std::lock_guard<std::mutex> lock(mutex);
     do {
         if (sz < 0x10) {
             key = int8_t(gen32());
diff --git a/src/realm/collection_parent.hpp b/src/realm/collection_parent.hpp
index 2fed4847fc2..7ac75585b6e 100644
--- a/src/realm/collection_parent.hpp
+++ b/src/realm/collection_parent.hpp
@@ -173,7 +173,7 @@ class CollectionParent : public std::enable_shared_from_this<CollectionParent> {
     SetBasePtr get_setbase_ptr(ColKey col_key) const;
     CollectionBasePtr get_collection_ptr(ColKey col_key) const;
 
-    int64_t generate_key(size_t sz) const;
+    static int64_t generate_key(size_t sz);
 };
 
 } // namespace realm