Disallow empty skeleton

Author: joladev

benches/hrw.exs

@@ -1,27 +1,25 @@
-nodes_tiny = Enum.map(1..10, fn i -> "key-#{i}" end)
-nodes_small = Enum.map(1..100, fn i -> "key-#{i}" end)
-nodes_medium = Enum.map(1..1000, fn i -> "key-#{i}" end)
-nodes_large = Enum.map(1..10000, fn i -> "key-#{i}" end)
+Mix.install([
+  {:hrw, path: Path.expand("..", __DIR__)},
+  {:benchee, "~> 1.5"},
+  {:ex_hash_ring, "~> 7.0"}
+])
+
+alias ExHashRing.Ring
+
+setup = fn n ->
+  nodes = Enum.map(1..n, &"node-#{&1}")
+  {:ok, ring} = Ring.start_link()
+  Ring.set_nodes(ring, nodes, :infinity)
+  %{nodes: nodes, skeleton: HRW.Skeleton.build(nodes), ring: ring}
+end
 
 Benchee.run(%{
-  "owner" => fn %{nodes: nodes} -> HRW.owner("test", nodes) end,
-  "skeleton pre-built" => fn %{skeleton: skeleton} -> HRW.Skeleton.owner("test", skeleton) end,
-  "skeleton every" => fn %{nodes: nodes} -> skeleton = HRW.Skeleton.build(nodes); HRW.Skeleton.owner("test", skeleton) end
+  "HRW.owner" => fn %{nodes: nodes} -> HRW.owner("test", nodes) end,
+  "HRW.Skeleton.owner" => fn %{skeleton: skeleton} -> HRW.Skeleton.owner("test", skeleton) end,
+  "ExHashRing.Ring.find_node" => fn %{ring: ring} -> Ring.find_node(ring, "test") end
 }, inputs: %{
-  "tiny" => %{
-    nodes: nodes_tiny,
-    skeleton: HRW.Skeleton.build(nodes_tiny)
-  },
-  "small" => %{
-    nodes: nodes_small,
-    skeleton: HRW.Skeleton.build(nodes_small)
-  },
-  "medium" => %{
-    nodes: nodes_medium,
-    skeleton: HRW.Skeleton.build(nodes_medium)
-  },
-  "large" => %{
-    nodes: nodes_large,
-    skeleton: HRW.Skeleton.build(nodes_large)
-  },
+  "tiny" => setup.(10),
+  "small" => setup.(100),
+  "medium" => setup.(1_000),
+  "large" => setup.(10_000),
 })

lib/hrw.ex

@@ -23,6 +23,7 @@ defmodule HRW do
       "server2"
 
   """
+  @spec owner(term(), [term()], keyword()) :: term()
   def owner(key, nodes, opts \\ []) do
     hash_fn = Keyword.get(opts, :hash_fn, &:erlang.phash2/1)
 
@@ -44,6 +45,7 @@ defmodule HRW do
       ["server2", "server3"]
 
   """
+  @spec owners(term(), [term()], non_neg_integer(), keyword()) :: [term()]
   def owners(key, nodes, count, opts \\ []) do
     hash_fn = Keyword.get(opts, :hash_fn, &:erlang.phash2/1)
 

lib/hrw/skeleton.ex

@@ -9,6 +9,12 @@ defmodule HRW.Skeleton do
 
   defstruct [:clusters, :fanout, :levels]
 
+  @type t :: %__MODULE__{
+          clusters: tuple(),
+          fanout: pos_integer(),
+          levels: non_neg_integer()
+        }
+
   @doc """
   Builds a skeleton from `nodes`.
 
@@ -23,7 +29,14 @@ defmodule HRW.Skeleton do
       #HRW.Skeleton<3 nodes, fanout: 3>
 
   """
-  def build(nodes, opts \\ []) do
+  @spec build([term()], keyword()) :: t()
+  def build(nodes, opts \\ [])
+
+  def build([], _opts) do
+    raise ArgumentError, "HRW.Skeleton.build/2 requires a non-empty list of nodes"
+  end
+
+  def build(nodes, opts) do
     fanout = Keyword.get(opts, :fanout, 3)
     size = Keyword.get(opts, :cluster_size, 16)
 
@@ -53,13 +66,12 @@ defmodule HRW.Skeleton do
       "server3"
 
   """
+  @spec owner(term(), t(), keyword()) :: term()
   def owner(key, %__MODULE__{} = skeleton, opts \\ []) do
     hash_fn = Keyword.get(opts, :hash_fn, &:erlang.phash2/1)
     do_owner(key, skeleton, 0, hash_fn)
   end
 
-  defp do_owner(_key, %__MODULE__{clusters: {}}, _salt, _hash_fn), do: nil
-
   defp do_owner(key, %__MODULE__{clusters: {cluster}}, _salt, hash_fn) do
     Enum.max_by(cluster, fn node -> hash_fn.({key, node}) end)
   end

mix.exs

@@ -22,8 +22,7 @@ defmodule HRW.MixProject do
   defp deps do
     [
       {:ex_doc, "~> 0.40.1", only: :dev},
-      {:credo, "~> 1.7", only: :dev},
-      {:benchee, "~> 1.5", only: :dev}
+      {:credo, "~> 1.7", only: :dev}
     ]
   end
 end