1 files changed, 59 insertions, 0 deletions
diff --git a/dom/base/DOMArena.h b/dom/base/DOMArena.h
new file mode 100644
index 0000000000..3f6d3c680c
--- /dev/null
+++ b/dom/base/DOMArena.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=2 sw=2 et tw=78:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+#ifndef DOM_Arena_h___
+#define DOM_Arena_h___
+#include "nsISupportsImpl.h"
+#include "mozmemory.h"
+
+#include "mozilla/mozalloc_oom.h"  // for mozalloc_handle_oom
+
+#define NS_DECL_DOMARENA_DESTROY void Destroy(void);
+
+#define NS_IMPL_DOMARENA_DESTROY(class)                              \
+  void class ::Destroy(void) {                                       \
+    if (StaticPrefs::dom_arena_allocator_enabled_AtStartup()) {      \
+      RefPtr<nsNodeInfoManager> nim = OwnerDoc()->NodeInfoManager(); \
+      RefPtr<DOMArena> arena =                                       \
+          HasFlag(NODE_KEEPS_DOMARENA)                               \
+              ? nsContentUtils::TakeEntryFromDOMArenaTable(this)     \
+              : nullptr;                                             \
+      this->~class();                                                \
+      MOZ_ASSERT(nim, "nsNodeInfoManager needs to be initialized");  \
+      nim->Free(this);                                               \
+    } else {                                                         \
+      delete this;                                                   \
+    }                                                                \
+  }
+
+namespace mozilla::dom {
+
+class DOMArena {
+ public:
+  friend class DocGroup;
+  DOMArena() {
+    arena_params_t params;
+    params.mMaxDirtyIncreaseOverride = 7;
+    params.mFlags = ARENA_FLAG_THREAD_MAIN_THREAD_ONLY;
+    mArenaId = moz_create_arena_with_params(&params);
+  }
+
+  NS_INLINE_DECL_REFCOUNTING(DOMArena)
+
+  void* Allocate(size_t aSize) {
+    void* ret = moz_arena_malloc(mArenaId, aSize);
+    if (!ret) {
+      mozalloc_handle_oom(aSize);
+    }
+    return ret;
+  }
+
+ private:
+  ~DOMArena() { moz_dispose_arena(mArenaId); }
+  arena_id_t mArenaId;
+};
+}  // namespace mozilla::dom
+#endif