Add patch_panel example

examples/patch_panel/.formatter.exs

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

examples/patch_panel/.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 3rd-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").
+patch_panel-*.tar
+

examples/patch_panel/README.md

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+# PatchPanel
+
+openflow controller that emulates a software patch panel
+
+## prerequisites
+
+ - Erlang 20 or higher
+ - Elixir 1.6.1 or higher
+ - OpenFlow switch supports version 1.3
+
+```iex
+# To add a patch link
+iex > :ok = PatchPanel.Openflow.Controller.create_patch("de780562fb45, 1, 2)
+# To delete a patch link
+iex > :ok = PatchPanel.Openflow.Controller.delete_patch("de780562fb45, 1, 2)
+```

examples/patch_panel/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,
+  callback_module: PatchPanel.Openflow.Controller,
+  callback_args: []

examples/patch_panel/lib/patch_panel.ex

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+defmodule PatchPanel do
+  @moduledoc """
+  Documentation for PatchPanel.
+  """
+
+  @doc """
+  Hello world.
+
+  ## Examples
+
+      iex> PatchPanel.hello
+      :world
+
+  """
+  def hello do
+    :world
+  end
+end

examples/patch_panel/lib/patch_panel/application.ex

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+defmodule PatchPanel.Application do
+  # See https://hexdocs.pm/elixir/Application.html
+  # for more information on OTP Applications
+  @moduledoc false
+
+  use Application
+
+  alias PatchPanel.Openflow
+
+  def start(_type, _args) do
+    import Supervisor.Spec
+
+    children = [
+      worker(Registry, [[keys: :unique, name: Openflow.Registry]], id: Openflow.Registry),
+    ]
+
+    opts = [strategy: :one_for_one, name: PatchPanel.Supervisor]
+    Supervisor.start_link(children, opts)
+  end
+end

examples/patch_panel/lib/patch_panel/openflow/controller.ex

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+defmodule PatchPanel.Openflow.Controller do
+  use GenServer
+  use Tres.Controller
+
+  import Logger
+
+  defmodule State do
+    defstruct [:datapath_id]
+  end
+
+  def create_patch(datapath_id, port_a, port_b) do
+    case PatchPanel.Openflow.Registry.lookup_pid(datapath_id) do
+      nil ->
+        {:error, :not_found}
+      pid when is_pid(pid) ->
+        GenServer.call(pid, {:create, port_a, port_b})
+    end
+  end
+
+  def delete_patch(datapath_id, port_a, port_b) do
+    case PatchPanel.Openflow.Registry.lookup_pid(datapath_id) do
+      nil ->
+        {:error, :not_found}
+      pid when is_pid(pid) ->
+        GenServer.call(pid, {:delete, port_a, port_b})
+    end
+  end
+
+  def start_link({datapath_id, _aux_id}, _start_args) do
+    GenServer.start_link(__MODULE__, [datapath_id])
+  end
+
+  def init([datapath_id]) do
+    :ok = info("Switch Connected: datapath_id = #{datapath_id}")
+    {:ok, _} = PatchPanel.Openflow.Registry.register(datapath_id)
+    {:ok, %State{datapath_id: datapath_id}}
+  end
+
+  def handle_call({:create, port_a, port_b}, _from, %State{datapath_id: datapath_id} = state) do
+    :ok = add_flow_entries(datapath_id, port_a, port_b)
+    {:reply, :ok, state}
+  end
+  def handle_call({:delete, port_a, port_b}, _from, %State{datapath_id: datapath_id} = state) do
+    :ok = del_flow_entries(datapath_id, port_a, port_b)
+    {:reply, :ok, state}
+  end
+
+  def handle_info({:switch_disconnected, reason}, %State{datapath_id: datapath_id} = state) do
+    :ok = warn("#{datapath_id} disconnected: reason = #{inspect(reason)}")
+    :ok = PatchPanel.Openflow.Registry.unregister(datapath_id)
+    {:stop, :normal, state}
+  end
+  def handle_info(_info, state) do
+    {:noreply, state}
+  end
+
+  def terminate(reason, state) do
+    {reason, state}
+  end
+
+  # private functions
+
+  defp add_flow_entries(datapath_id, port_a, port_b) do
+    :ok = send_flow_mod_add(
+      datapath_id,
+      match: Match.new(in_port: port_a),
+      instructions: [ApplyActions.new(Output.new(port_b))]
+    )
+
+    :ok = send_flow_mod_add(
+      datapath_id,
+      match: Match.new(in_port: port_b),
+      instructions: [ApplyActions.new(Output.new(port_a))]
+    )
+  end
+
+  defp del_flow_entries(datapath_id, port_a, port_b) do
+    :ok = send_flow_mod_delete(datapath_id, match: Match.new(in_port: port_a))
+    :ok = send_flow_mod_delete(datapath_id, match: Match.new(in_port: port_b))
+  end
+end

examples/patch_panel/lib/patch_panel/openflow/registry.ex

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+defmodule PatchPanel.Openflow.Registry do
+  def register(datapath_id) do
+    {:ok, _} = Registry.register(__MODULE__, datapath_id, [])
+  end
+
+  def unregister(datapath_id) do
+    :ok = Registry.unregister(__MODULE__, datapath_id)
+  end
+
+  def lookup_pid(datapath_id) do
+    case Registry.lookup(__MODULE__, datapath_id) do
+      [{pid, _}] -> pid
+      [] -> nil
+    end
+  end
+end

examples/patch_panel/mix.exs

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+defmodule PatchPanel.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :patch_panel,
+      version: "0.1.0",
+      elixir: "~> 1.6",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger],
+      mod: {PatchPanel.Application, []}
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [{:tres, path: "../../../tres"}]
+  end
+end

examples/patch_panel/mix.lock

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+%{
+  "eovsdb": {:git, "https://github.com/shun159/eovsdb.git", "1ff1572708d72fd25631c681f2102407903252a3", [branch: "master"]},
+  "jsone": {:git, "https://github.com/sile/jsone.git", "eecc9666c7165e1870b78a7a762549ae8d1c391b", [tag: "1.2.1"]},
+  "ranch": {:hex, :ranch, "1.4.0", "10272f95da79340fa7e8774ba7930b901713d272905d0012b06ca6d994f8826b", [:rebar3], [], "hexpm"},
+  "uuid": {:git, "https://github.com/avtobiff/erlang-uuid.git", "585c2474afb4a597ae8c8bf6d21e5a9c73f18e0b", [tag: "v0.5.0"]},
+}

examples/patch_panel/test/patch_panel_test.exs

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

examples/patch_panel/test/test_helper.exs

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+ExUnit.start()