radix: Add a method to skip nulls and use it when initializing

I think the semantics used to be that the iterator would always start at the first non-null element, which I broke when I switched to the iterative implementation. This fixes that and introduces a method that will be useful once iterators can point to null elements.

radix: Add a method to skip nulls and use it when initializing
c3856fc7 · Austin Clements · e00b4d6c · c3856fc7 · c3856fc7
--- a/include/radix.hh
+++ b/include/radix.hh
@@ -241,6 +241,14 @@ struct radix_iterator {
    return path_[level_]->load().elem();
  }
+  // Advance the iterator until it points at a non-null entry or end.
+  // If the current element is non-null, does nothing.
+  void skip_nulls()
+  {
+    if (path_[level_]->load().is_null())
+      ++(*this);
+  }
  // Compare equality on just the key.
  bool operator==(const radix_iterator &other) {
    return r_ == other.r_ && k_ == other.k_; }

--- a/kernel/radix.cc
+++ b/kernel/radix.cc
@@ -261,6 +261,9 @@ radix_iterator::prime_path()
    node = path_[level_];
  }
+  // Find a real element
+  skip_nulls();
  dprintf("%p: Adjusted: k = %lx\n", r_, k_);
 }