free

fn free(context: *anyopaque, memory: []u8, alignment: Alignment, ra: usize) void {
    _ = context;
    _ = ra;
    const class = sizeClassIndex(memory.len, alignment);
    if (class >= size_class_count) {
        @branchHint(.unlikely);
        return PageAllocator.unmap(@alignCast(memory));
    }

    const node: *usize = @ptrCast(@alignCast(memory.ptr));

    const t = Thread.lock();
    defer t.unlock();

    node.* = t.frees[class];
    t.frees[class] = @intFromPtr(node);
}