feat(): add count/1

lib/rox.ex

@@ -276,4 +276,16 @@ defmodule Rox do
 
     Keyword.merge(rest, converted)
   end
+
+
+  @doc """
+  Return the approximate number of keys in the default column family.
+
+  Implemented by calling GetIntProperty with `rocksdb.estimate-num-keys`
+
+  """
+  @spec count(db_handle) :: non_neg_integer | {:error, any}
+  def count(db) do
+    :erocksdb.count(db)
+  end
 end

test/rox_test.exs

@@ -46,4 +46,12 @@ defmodule RoxTest do
 
     Rox.stream_keys(db) |> Enum.take(1)
   end
+
+  test "count", %{db: db} do
+    count =
+      Rox.count(db)
+
+    assert is_number(count)
+    assert count >= 0
+  end
 end