browser: inline finalizer callbacks

Assisted-By: devx/3b7fd0ba-7378-40f0-a356-c0f5ce04cd1e

src/browser/Page.zig

@@ -86,7 +86,7 @@ identity: js.Identity = .{},
 // Zig instance ptr. The backing FinalizerCallback.Identity structs come from
 // Browser.fc_identity_pool so they outlive the Page (and the Session) for v8
 // weak-callback safety.
-finalizer_callbacks: std.AutoHashMapUnmanaged(usize, *js.FinalizerCallback) = .empty,
+finalizer_callbacks: std.AutoHashMapUnmanaged(usize, js.FinalizerCallback) = .empty,
 
 // Persisted v8 handles owned by this Page. Handles that outlive the Page are
 // reset on teardown; handles that can be released early are dropped
@@ -205,7 +205,7 @@ pub fn deinit(self: *Page) void {
     {
         var it = self.finalizer_callbacks.valueIterator();
         while (it.next()) |fc| {
-            fc.*.deinit(self);
+            fc.deinit(self);
         }
         self.finalizer_callbacks = .empty;
     }

src/browser/js/Local.zig

@@ -339,9 +339,9 @@ pub fn mapZigInstanceToJs(self: *const Local, js_obj_handle: ?*const v8.Object,
                     // so that we can cleanup on Page teardown if v8 doesn't finalize.
                     errdefer _ = page.finalizer_callbacks.remove(finalizer_ptr_id);
                     finalizer.acquire_ref(finalizer_ptr_id);
-                    finalizer_gop.value_ptr.* = try self.createFinalizerCallback(resolved_ptr_id, finalizer_ptr_id, finalizer.release_ref_from_zig);
+                    finalizer_gop.value_ptr.* = createFinalizerCallback(resolved_ptr_id, finalizer_ptr_id, finalizer.release_ref_from_zig);
                 }
-                const fc = finalizer_gop.value_ptr.*;
+                const fc = finalizer_gop.value_ptr;
                 const browser = session.browser;
                 const identity_finalizer = try browser.fc_identity_pool.create();
                 identity_finalizer.* = .{
@@ -1316,7 +1316,7 @@ fn resolveT(comptime T: type, value: *T) Resolved {
                     }
 
                     const finalizer_ptr_id = identity_finalizer.finalizer_ptr_id;
-                    const fc = page.finalizer_callbacks.get(finalizer_ptr_id) orelse return;
+                    const fc = page.finalizer_callbacks.getPtr(finalizer_ptr_id) orelse return;
 
                     {
                         // Unlink this identity from the FC's intrusive list
@@ -1346,7 +1346,6 @@ fn resolveT(comptime T: type, value: *T) Resolved {
                         // Remove from map before releaseRef to prevent address reuse issues.
                         _ = page.finalizer_callbacks.remove(finalizer_ptr_id);
                         FT.releaseRef(@ptrFromInt(finalizer_ptr_id), page);
-                        page.releaseArena(fc.arena);
                     }
                 }
 
@@ -1601,8 +1600,6 @@ pub fn debugContextId(self: *const Local) i32 {
 }
 
 fn createFinalizerCallback(
-    self: *const Local,
-
     // Key in identity map
     // The most specific value (KeyboardEvent, not Event)
     resolved_ptr_id: usize,
@@ -1611,21 +1608,12 @@ fn createFinalizerCallback(
     // What actually gets acquired / released / deinit
     finalizer_ptr_id: usize,
     release_ref: *const fn (ptr_id: usize, page: *Page) void,
-) !*FinalizerCallback {
-    const page = self.ctx.page;
-
-    const arena = try page.getArena(.tiny, "FinalizerCallback");
-    errdefer page.releaseArena(arena);
-
-    const fc = try arena.create(FinalizerCallback);
-    fc.* = .{
-        .page = page,
-        .arena = arena,
+) FinalizerCallback {
+    return .{
         .release_ref = release_ref,
         .resolved_ptr_id = resolved_ptr_id,
         .finalizer_ptr_id = finalizer_ptr_id,
     };
-    return fc;
 }
 
 // Encapsulates a Local and a HandleScope. When we're going from V8->Zig

src/browser/js/js.zig

@@ -479,8 +479,6 @@ test "TaggedAnyOpaque" {
 // Page. This is to ensure that, if v8 doesn't finalize the value, we can
 // release on Page teardown.
 pub const FinalizerCallback = struct {
-    page: *Page,
-    arena: Allocator,
     resolved_ptr_id: usize,
     finalizer_ptr_id: usize,
     release_ref: *const fn (ptr_id: usize, page: *Page) void,
@@ -528,7 +526,6 @@ pub const FinalizerCallback = struct {
             id = identity.next;
         }
         self.release_ref(self.finalizer_ptr_id, page);
-        page.releaseArena(self.arena);
     }
 };
 

src/browser/tests/net/request.html

@@ -268,3 +268,9 @@
   }
   testing.expectError('TypeError', () => new Request('https://example.com', { priority: 'bogus' }));
 </script>
+
+<script id=many_live_requests>
+  const requests = Array.from({ length: 1024 }, (_, i) => new Request(`https://example.com/${i}`));
+  testing.expectEqual(1024, requests.length);
+  testing.expectEqual('https://example.com/1023', requests[1023].url);
+</script>