[#6] Adding Ethereum Latest Block Collector

lib/poa_agent/format.ex

@@ -9,6 +9,15 @@ defmodule POAAgent.Format do
 
       ## A literal hex string like "0x0123456789abcdef"
       @type t :: String.t
+
+      @spec decimalize(t) :: String.t | :format_error
+      def decimalize("0x" <> trimmed_hex) do
+        {integer, _} = Integer.parse(trimmed_hex, 16)
+        Integer.to_string(integer)
+      end
+      def decimalize(_) do
+        :format_error
+      end
     end
 
     defmodule TrimmedHex do

lib/poa_agent/plugins/collector.ex

@@ -67,10 +67,10 @@ defmodule POAAgent.Plugins.Collector do
 
         def collect(:no_state) do
           IO.puts "I am collecting data!"
-          {:ok, "data retrieved", :no_state}
+          {:transfer, "data retrieved", :no_state}
         end
 
-        def terminate(_reason, _state) do
+        def terminate(_state) do
           :ok
         end
 
@@ -89,9 +89,12 @@ defmodule POAAgent.Plugins.Collector do
 
   @doc """
     In this callback is where the metrics collection logic must be placed.
-    It must return `{:ok, data, state}`. `data` is the retrieved metrics.
+    It must return `{:transfer, data, state}` where `data` is the retrieved metrics or
+    `{:notransfer, state} when for some reason we don't want to send data to the transfer int
+    that moment
   """
-  @callback collect(state :: any()) :: {:ok, data :: any(), state :: any()}
+  @callback collect(state :: any()) :: {:transfer, data :: any(), state :: any()}
+                                     | {:notransfer, state :: any()}
 
   @doc """
     This callback is called just before the Process goes down. This is a good place for closing connections.
@@ -122,8 +125,11 @@ defmodule POAAgent.Plugins.Collector do
 
       @doc false
       def handle_info(:collect, state) do
-        {:ok, data, internal_state} = collect(state.internal_state)
-        transfer(data, state.label, state.transfers)
+        internal_state =
+          state.internal_state
+          |> collect()
+          |> transfer(state.label, state.transfers)
+
         set_collector_timer(state.frequency)
         {:noreply, %{state | internal_state: internal_state}}
       end
@@ -147,9 +153,12 @@ defmodule POAAgent.Plugins.Collector do
       end
 
       @doc false
-      defp transfer(data, label, transfers) do
+      defp transfer({:transfer, data, internal_state}, label, transfers) do
         Enum.each(transfers, &GenServer.cast(&1, %{label: label, data: data}))
-        :ok
+        internal_state
+      end
+      defp transfer({:notransfer, internal_state}, _label, _transfers) do
+        internal_state
       end
 
       @doc false

lib/poa_agent/plugins/collectors/eth/latest_block.ex

@@ -0,0 +1,98 @@
+defmodule POAAgent.Plugins.Collectors.Eth.LatestBlock do
+  use POAAgent.Plugins.Collector
+
+  @moduledoc """
+  This is a Collector's Plugin which makes requests to a Ethereum node in order to know if
+  a new block has been added.
+
+  This Collector needs the url of the node to iteract. That url must be placed in the args field 
+  in the config file. For example:
+
+      {:eth_latest_block, POAAgent.Plugins.Collectors.Eth.LatestBlock, 500, :latest_block, [url: "http://localhost:8545"]}
+
+  In this example, the Collector will check with the Ethereum node every 500 miliseconds if a new block 
+  has been added to the blockchain. If that is the case it will retrieve it and send it to the Transfers
+  encapsulated in a `POAAgent.Entity.Ethereum.Block` struct
+
+  """
+
+  @typep internal_state :: %{last_block: String.t}
+
+  @doc false
+  @spec init_collector(term()) :: {:ok, internal_state()}
+  def init_collector(args) do
+    :ok = config(args)
+
+    {:ok, %{last_block: get_latest_block()}}
+  end
+
+  @doc false
+  @spec collect(internal_state()) :: term()
+  def collect(%{last_block: latest_block} = state) do
+    case get_latest_block() do
+      nil ->
+        {:notransfer, state}
+      ^latest_block ->
+        {:notransfer, state}
+      latest_block ->
+        {:ok, block} = Ethereumex.HttpClient.eth_get_block_by_number(latest_block, :false)
+        {:transfer, format_block(block), %{state | last_block: latest_block}}
+    end
+  end
+
+  @doc false
+  @spec terminate(internal_state()) :: :ok
+  def terminate(_state) do
+    :ok
+  end
+
+  @doc false
+  defp config([url: url]) do
+    Application.put_env(:ethereumex, :url, url)
+    :ok
+  end
+
+  @doc false
+  defp get_latest_block() do
+    case Ethereumex.HttpClient.eth_block_number do
+      {:ok, latest_block} -> latest_block
+      _ -> nil
+    end
+  end
+
+  @doc false
+  defp format_block(block) do
+    difficulty = POAAgent.Format.Literal.Hex.decimalize(block["difficulty"])
+    gas_limit = String.to_integer(POAAgent.Format.Literal.Hex.decimalize(block["gasLimit"]))
+    gas_used = String.to_integer(POAAgent.Format.Literal.Hex.decimalize(block["gasUsed"]))
+    number = String.to_integer(POAAgent.Format.Literal.Hex.decimalize(block["number"]))
+    size = String.to_integer(POAAgent.Format.Literal.Hex.decimalize(block["size"]))
+    timestamp = String.to_integer(POAAgent.Format.Literal.Hex.decimalize(block["timestamp"]))
+    total_difficulty = POAAgent.Format.Literal.Hex.decimalize(block["totalDifficulty"])
+
+    %POAAgent.Entity.Ethereum.Block{
+      author: block["author"],
+      difficulty: difficulty,
+      extra_data: block["extraData"],
+      gas_limit: gas_limit,
+      gas_used: gas_used,
+      hash: block["hash"],
+      miner: block["miner"],
+      number: number,
+      parent_hash: block["parentHash"],
+      receipts_root: block["receiptsRoot"],
+      seal_fields: block["sealFields"],
+      sha3_uncles: block["sha3Uncles"],
+      signature: block["signature"],
+      size: size,
+      state_root: block["stateRoot"],
+      step: block["step"],
+      timestamp: timestamp,
+      total_difficulty: total_difficulty,
+      transactions: block["transactions"],
+      transactions_root: block["transactionsRoot"],
+      uncles: block["uncles"]
+    }
+  end
+
+end

lib/poa_agent/plugins/transfer.ex

@@ -49,7 +49,7 @@ defmodule POAAgent.Plugins.Transfer do
           {:ok, :no_state}
         end
 
-        def terminate(_reason, _state) do
+        def terminate(_state) do
           :ok
         end
 

mix.exs

@@ -24,8 +24,12 @@ defmodule POAAgent.MixProject do
 
   defp deps do
     [
+      {:ethereumex, "~> 0.3"},
+
+      # Tests
       {:credo, "~> 0.9", only: [:dev, :test], runtime: false},
       {:dialyxir, "~> 0.5", only: [:dev], runtime: false},
+      {:mock, "~> 0.3", only: [:test], runtime: false},
 
       # Docs
       {:ex_doc, "~> 0.18", only: :dev, runtime: false}
@@ -41,6 +45,9 @@ defmodule POAAgent.MixProject do
         "Plugins": [
           POAAgent.Plugins.Collector,
           POAAgent.Plugins.Transfer,
+        ],
+        "Ethereum Plugins": [
+          POAAgent.Plugins.Collectors.Eth.LatestBlock
         ]
       ]
     ]

mix.lock

@@ -1,8 +1,20 @@
 %{
   "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [], [], "hexpm"},
+  "certifi": {:hex, :certifi, "2.3.1", "d0f424232390bf47d82da8478022301c561cf6445b5b5fb6a84d49a9e76d2639", [:rebar3], [{:parse_trans, "3.2.0", [hex: :parse_trans, repo: "hexpm", optional: false]}], "hexpm"},
   "credo": {:hex, :credo, "0.9.2", "841d316612f568beb22ba310d816353dddf31c2d94aa488ae5a27bb53760d0bf", [], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:poison, ">= 0.0.0", [hex: :poison, repo: "hexpm", optional: false]}], "hexpm"},
   "dialyxir": {:hex, :dialyxir, "0.5.1", "b331b091720fd93e878137add264bac4f644e1ddae07a70bf7062c7862c4b952", [], [], "hexpm"},
   "earmark": {:hex, :earmark, "1.2.5", "4d21980d5d2862a2e13ec3c49ad9ad783ffc7ca5769cf6ff891a4553fbaae761", [], [], "hexpm"},
+  "ethereumex": {:hex, :ethereumex, "0.3.2", "ee01a49c781c9751317b2918f799e84185203c81c8314ebebb1f1e22b754db3e", [], [{:httpoison, "~> 1.0.0", [hex: :httpoison, repo: "hexpm", optional: false]}, {:poison, "~> 3.1.0", [hex: :poison, repo: "hexpm", optional: false]}], "hexpm"},
   "ex_doc": {:hex, :ex_doc, "0.18.3", "f4b0e4a2ec6f333dccf761838a4b253d75e11f714b85ae271c9ae361367897b7", [], [{:earmark, "~> 1.1", [hex: :earmark, repo: "hexpm", optional: false]}], "hexpm"},
+  "hackney": {:hex, :hackney, "1.12.1", "8bf2d0e11e722e533903fe126e14d6e7e94d9b7983ced595b75f532e04b7fdc7", [:rebar3], [{:certifi, "2.3.1", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "5.1.1", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "1.0.1", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "1.0.2", [hex: :mimerl, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "1.1.1", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}], "hexpm"},
+  "httpoison": {:hex, :httpoison, "1.0.0", "1f02f827148d945d40b24f0b0a89afe40bfe037171a6cf70f2486976d86921cd", [], [{:hackney, "~> 1.8", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm"},
+  "idna": {:hex, :idna, "5.1.1", "cbc3b2fa1645113267cc59c760bafa64b2ea0334635ef06dbac8801e42f7279c", [:rebar3], [{:unicode_util_compat, "0.3.1", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm"},
+  "meck": {:hex, :meck, "0.8.9", "64c5c0bd8bcca3a180b44196265c8ed7594e16bcc845d0698ec6b4e577f48188", [], [], "hexpm"},
+  "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm"},
+  "mimerl": {:hex, :mimerl, "1.0.2", "993f9b0e084083405ed8252b99460c4f0563e41729ab42d9074fd5e52439be88", [:rebar3], [], "hexpm"},
+  "mock": {:hex, :mock, "0.3.1", "994f00150f79a0ea50dc9d86134cd9ebd0d177ad60bd04d1e46336cdfdb98ff9", [], [{:meck, "~> 0.8.8", [hex: :meck, repo: "hexpm", optional: false]}], "hexpm"},
+  "parse_trans": {:hex, :parse_trans, "3.2.0", "2adfa4daf80c14dc36f522cf190eb5c4ee3e28008fc6394397c16f62a26258c2", [:rebar3], [], "hexpm"},
   "poison": {:hex, :poison, "3.1.0", "d9eb636610e096f86f25d9a46f35a9facac35609a7591b3be3326e99a0484665", [], [], "hexpm"},
+  "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.1", "28a4d65b7f59893bc2c7de786dec1e1555bd742d336043fe644ae956c3497fbe", [:make, :rebar], [], "hexpm"},
+  "unicode_util_compat": {:hex, :unicode_util_compat, "0.3.1", "a1f612a7b512638634a603c8f401892afbf99b8ce93a45041f8aaca99cadb85e", [:rebar3], [], "hexpm"},
 }

test/plugins_test.exs

@@ -10,7 +10,7 @@ defmodule POAAgent.PluginsTest do
       end
 
       def collect(:no_state) do
-        {:ok, "data retrieved", :no_state}
+        {:transfer, "data retrieved", :no_state}
       end
 
       def terminate(_state) do
@@ -64,7 +64,7 @@ defmodule POAAgent.PluginsTest do
       def collect(test_pid) do
         data = "data retrieved"
         send test_pid, {:sent, self(), data}
-        {:ok, data, test_pid}
+        {:transfer, data, test_pid}
       end
 
       def terminate(_state) do

test/poa_agent/plugins/collectors/eth/latest_block_test.exs

@@ -0,0 +1,65 @@
+defmodule POAAgent.Plugins.Collectors.Eth.LatestBlockTest do
+  use ExUnit.Case
+  import Mock
+
+  test "latest block sent to the transfer" do
+    with_mock Ethereumex.HttpClient, [
+        eth_get_block_by_number: fn(_, _) -> {:ok, ethereumex_block()} end,
+        eth_block_number: fn() -> {:ok, 0} end
+      ] do
+
+      {:transfer, block, _} = POAAgent.Plugins.Collectors.Eth.LatestBlock.collect(%{last_block: 1})
+      assert block == expected_block()
+    end
+  end
+
+  defp ethereumex_block() do
+    %{"author" => "0xdf9c9701e434c5c9f755ef8af18d6a4336550206",
+      "difficulty" => "0xfffffffffffffffffffffffffffffffd",
+      "extraData" => "0xd583010a008650617269747986312e32342e31826c69",
+      "gasLimit" => "0x7a1200",
+      "gasUsed" => "0x0",
+      "hash" =>
+      "0xf974c07ac165f8490ef225d47f24b81161e2f2bd8ffd5b926a1a37bb22a02462",
+      "miner" => "0xdf9c9701e434c5c9f755ef8af18d6a4336550206",
+      "number" => "0x3b7d9",
+      "parentHash" => "0xaf6f3c960045aea9edda21e119984028211f4eb3233700c18efca4f8e4c0c2fc",
+      "receiptsRoot" => "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
+      "sealFields" => ["0x841230dcf5", "0xb841b5ebbb6d5ff185598a86d5e96d9a238ed020b239e94eb1219a6ce1e425c7f23b768ce411474e935c2e3ee61f812ded702e1b7ca2d1c41ab4053f4420440b651901"],
+      "sha3Uncles" => "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
+      "signature" => "b5ebbb6d5ff185598a86d5e96d9a238ed020b239e94eb1219a6ce1e425c7f23b768ce411474e935c2e3ee61f812ded702e1b7ca2d1c41ab4053f4420440b651901",
+      "size" => "0x243",
+      "stateRoot" => "0x590452386894d2ff6ec146a23f61fd0f459259bf0e20c59504c7f2fa3e4feeb1",
+      "step" => "305192181",
+      "timestamp" => "0x5af450c9",
+      "totalDifficulty" => "0x3b7d8ffffffffffffffffffffffffedcd6b32", "transactions" => [],
+      "transactionsRoot" => "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
+      "uncles" => []}
+  end
+
+  defp expected_block() do
+    %POAAgent.Entity.Ethereum.Block{
+      author: "0xdf9c9701e434c5c9f755ef8af18d6a4336550206",
+      difficulty: "340282366920938463463374607431768211453",
+      extra_data: "0xd583010a008650617269747986312e32342e31826c69",
+      gas_limit: 8_000_000,
+      gas_used: 0,
+      hash: "0xf974c07ac165f8490ef225d47f24b81161e2f2bd8ffd5b926a1a37bb22a02462",
+      miner: "0xdf9c9701e434c5c9f755ef8af18d6a4336550206",
+      number: 243_673,
+      parent_hash: "0xaf6f3c960045aea9edda21e119984028211f4eb3233700c18efca4f8e4c0c2fc",
+      receipts_root: "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
+      seal_fields: ["0x841230dcf5", "0xb841b5ebbb6d5ff185598a86d5e96d9a238ed020b239e94eb1219a6ce1e425c7f23b768ce411474e935c2e3ee61f812ded702e1b7ca2d1c41ab4053f4420440b651901"],
+      sha3_uncles: "0x1dcc4de8dec75d7aab85b567b6ccd41ad312451b948a7413f0a142fd40d49347",
+      signature: "b5ebbb6d5ff185598a86d5e96d9a238ed020b239e94eb1219a6ce1e425c7f23b768ce411474e935c2e3ee61f812ded702e1b7ca2d1c41ab4053f4420440b651901",
+      size: 579,
+      state_root: "0x590452386894d2ff6ec146a23f61fd0f459259bf0e20c59504c7f2fa3e4feeb1",
+      step: "305192181",
+      timestamp: 1_525_960_905,
+      total_difficulty: "82917625194725838207510880716721255084813106",
+      transactions: [],
+      transactions_root: "0x56e81f171bcc55a6ff8345e692c0f86e5b48e01b996cadc001622fb5e363b421",
+      uncles: []
+    }
+  end
+end