example: Add example for NXAST_LEARN

examples/nx_learning_switch/.formatter.exs

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+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

examples/nx_learning_switch/.gitignore

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+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+nx_learning_switch-*.tar
+

examples/nx_learning_switch/README.md

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+# NxLearningSwitch
+
+Example for a very simple-minded MAC learning switch

examples/nx_learning_switch/config/config.exs

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+# This file is responsible for configuring your application
+# and its dependencies with the aid of the Mix.Config module.
+use Mix.Config
+
+config :tres,
+  protocol:        :tcp,
+  port:            6653,
+  max_connections: 10,
+  num_acceptors:   10,
+  callback_module: NxLearningSwitch,
+  callback_args:   []
+
+config :logger,
+  level: :debug,
+  format: "$date $time [$level] $metadata$message\n",
+  metadata: [:application],
+  handle_otp_reports: true

examples/nx_learning_switch/lib/nx_learning_switch.ex

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+defmodule NxLearningSwitch do
+  @moduledoc """
+  Emulates Layer2 switch
+  """
+
+  use GenServer
+  use Tres.Controller
+
+  import Logger
+
+  # API functions
+
+  def start_link(datapath_id, _args) do
+    GenServer.start_link(__MODULE__, [datapath_id])
+  end
+
+  # GenServer callback functions
+
+  @impl GenServer
+  def init([{datapath_id, _aux_id}]) do
+    :ok = info("Connected: datapath_id: #{datapath_id}")
+    {:ok, datapath_id, {:continue, :init}}
+  end
+
+  @impl GenServer
+  def handle_continue(:init, datapath_id) do
+    :ok = l2_learning_flow(datapath_id)
+    :ok = l2_flooding_flows(datapath_id)
+    {:noreply, datapath_id}
+  end
+
+  @impl GenServer
+  def handle_call(_request, _from, state) do
+    {:reply, :ok, state}
+  end
+
+  @impl GenServer
+  def handle_cast(_request, state) do
+    {:noreply, state}
+  end
+
+  @impl GenServer
+  def handle_info({:switch_disconnected, reason}, datapath_id) do
+    :ok = warn("Disconnected: datapath_id: #{datapath_id} by #{inspect(reason)}")
+    {:stop, :normal, datapath_id}
+  end
+
+  @impl GenServer
+  def handle_info(_info, state) do
+    {:noreply, state}
+  end
+
+  ## private functions
+
+  defp l2_learning_flow(datapath_id) do
+    send_flow_mod_add(
+      datapath_id,
+      table_id: 0,
+      instructions: ApplyActions.new([
+        NxLearn.new(
+          table_id: 1,
+          priority: 2,
+          hard_timeout: 10,
+          flow_specs: [
+            NxFlowSpecMatch.new(
+              src: :nx_eth_src,
+              dst: :nx_eth_dst
+            ),
+            NxFlowSpecMatch.new(
+              src: :nx_vlan_tci,
+              dst: :nx_vlan_tci,
+              offset: 0,
+              n_bits: 12
+            ),
+            NxFlowSpecOutput.new(
+              src: :nx_in_port
+            )
+          ]
+        ),
+        NxResubmitTable.new(1)
+      ])
+    )
+  end
+
+  defp l2_flooding_flows(datapath_id) do
+    send_flow_mod_add(
+      datapath_id,
+      table_id: 1,
+      priority: 0,
+      instructions: ApplyActions.new(Output.new(:flood))
+    )
+  end
+end

examples/nx_learning_switch/mix.exs

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+defmodule NxLearningSwitch.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :nx_learning_switch,
+      version: "0.1.0",
+      elixir: "~> 1.8",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      {:tres, path: "../../../tres"}
+    ]
+  end
+end

examples/nx_learning_switch/mix.lock

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+%{
+  "ranch": {:hex, :ranch, "1.7.1", "6b1fab51b49196860b733a49c07604465a47bdb78aa10c1c16a3d199f7f8c881", [:rebar3], [], "hexpm"},
+}

examples/nx_learning_switch/test/nx_learning_switch_test.exs

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+defmodule NxLearningSwitchTest do
+  use ExUnit.Case
+  doctest NxLearningSwitch
+
+  test "greets the world" do
+    assert NxLearningSwitch.hello() == :world
+  end
+end

examples/nx_learning_switch/test/test_helper.exs

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+ExUnit.start()