Merge pull request #31 from poanetwork/ferigis.30.Keep_last_stats

[#30] sending last metrics when the dashboard connects to the backend

lib/poa_backend/receivers/dashboard.ex

@@ -23,6 +23,11 @@ defmodule POABackend.Receivers.Dashboard do
 
   use POABackend.Receiver
 
+  # we store the last metrics in a ETS table because when a dashboard is connected it can wait a lot until
+  # the stats get updated
+
+  @last_metrics_table :last_metrics_table
+
   alias __MODULE__
   alias POABackend.Protocol.Message
 
@@ -95,6 +100,8 @@ defmodule POABackend.Receivers.Dashboard do
   def init_receiver(opts) do
     :ok = start_websockets_server(opts)
 
+    :ok = set_up_last_metrics_table()
+
     {:ok, %{clients: []}}
   end
 
@@ -105,6 +112,17 @@ defmodule POABackend.Receivers.Dashboard do
   end
 
   def handle_message({:add_client, client}, %{clients: clients} = state) do
+
+    # we send the latest metrics in order to catch up
+    stored_metrics = :ets.tab2list(@last_metrics_table)
+
+    for {_, metrics} <- stored_metrics do
+      metrics_list = Map.to_list(metrics)
+      for {_, metric} <- metrics_list do
+        send(client, metric)
+      end
+    end
+
     {:ok, %{state | clients: [client | clients]}}
   end
 
@@ -163,6 +181,8 @@ defmodule POABackend.Receivers.Dashboard do
       end
     end
 
+    save_metrics(metrics)
+
     :ok
   end
 
@@ -170,4 +190,49 @@ defmodule POABackend.Receivers.Dashboard do
     dispatch_metric([metric], clients)
   end
 
+  defp save_metrics(metrics) do
+    for metric <- metrics do
+      case metric.data["type"] do
+        "information" ->
+          save_last_information(metric)
+        "statistics" ->
+          save_last_stats(metric)
+        _ ->
+          :continue
+      end
+    end
+
+    :ok
+  end
+
+  defp save_last_information(%Message{} = metric) do
+    case :ets.lookup(@last_metrics_table, metric.agent_id) do
+      [] ->
+        :ets.insert(@last_metrics_table, {metric.agent_id, %{information: metric}})
+      [{_, last_metrics}] ->
+        last_metrics = Map.put(last_metrics, :information, metric)
+        :ets.insert(@last_metrics_table, {metric.agent_id, last_metrics})
+    end
+
+    :ok
+  end
+
+  defp save_last_stats(%Message{} = metric) do
+    case :ets.lookup(@last_metrics_table, metric.agent_id) do
+      [] ->
+        :ets.insert(@last_metrics_table, {metric.agent_id, %{stats: metric}})
+      [{_, last_metrics}] ->
+        last_metrics = Map.put(last_metrics, :stats, metric)
+        :ets.insert(@last_metrics_table, {metric.agent_id, last_metrics})
+    end
+
+    :ok
+  end
+
+  defp set_up_last_metrics_table do
+    :ets.new(@last_metrics_table, [:named_table])
+
+    :ok
+  end
+
 end

test/receivers/dashboard_test.exs

@@ -8,8 +8,9 @@ defmodule Receivers.DashboardTest do
   defmodule Client do
     use WebSockex
 
-    def send(client, message) do
+    def send(client, message, caller) do
       WebSockex.send_frame(client, {:text, message})
+      Kernel.send(caller, :message_sent)
     end
 
     def start_link(address, state, opts \\ []) do
@@ -45,10 +46,32 @@ defmodule Receivers.DashboardTest do
     assert_receive ^expected_message, 20_000
   end
 
+  test "When the Dashboard connects already exists last metrics in the Backend" do
+
+    # we send the metrics twice in order to complete all the cases in the Receiver
+    # when the ets doesn't have the agentid and when it already exists
+    POABackend.Metric.add(:ethereum_metrics, [information_message(), stats_message(), information_message()])
+    POABackend.Metric.add(:ethereum_metrics, [information_message2(), stats_message2()])
+
+    Client.start_link("http://localhost:8181/ws", self(), [{:extra_headers, [{"wssecret", "mywssecret"}]}])
+
+    expected_information_message = expected_information_message()
+    expected_stats_message = expected_stats_message()
+    expected_information_message2 = expected_information_message2()
+    expected_stats_message2 = expected_stats_message2()
+
+    assert_receive ^expected_information_message, 20_000
+    assert_receive ^expected_stats_message, 20_000
+    assert_receive ^expected_information_message2, 20_000
+    assert_receive ^expected_stats_message2, 20_000
+  end
+
   test "handle messages from the client to the server (test coverage)" do
     {:ok, client} = Client.start_link("http://localhost:8181/ws", self(), [{:extra_headers, [{"wssecret", "mywssecret"}]}])
 
-    Client.send(client, "hello")
+    Client.send(client, "hello", self())
+
+    assert_receive :message_sent, 20_000
   end
 
   test "http call to the server (test coverage)" do
@@ -65,4 +88,35 @@ defmodule Receivers.DashboardTest do
     Message.new("agentid1", :ethereum_metric, :data, %{a: "a", b: "b", c: "c"})
   end
 
+  defp information_message do
+    Message.new("agentid", :ethereum_metric, :data, %{"type" => "information"})
+  end
+
+  defp stats_message do
+    Message.new("agentid", :ethereum_metric, :data, %{"type" => "statistics"})
+  end
+
+  defp information_message2 do
+    Message.new("agentid2", :ethereum_metric, :data, %{"type" => "information"})
+  end
+
+  defp stats_message2 do
+    Message.new("agentid2", :ethereum_metric, :data, %{"type" => "statistics"})
+  end
+
+  defp expected_information_message do
+    "{\"data\":{\"type\":\"information\"},\"agent_id\":\"agentid\"}"
+  end
+
+  defp expected_stats_message do
+    "{\"data\":{\"type\":\"statistics\"},\"agent_id\":\"agentid\"}"
+  end
+
+  defp expected_information_message2 do
+    "{\"data\":{\"type\":\"information\"},\"agent_id\":\"agentid2\"}"
+  end
+
+  defp expected_stats_message2 do
+    "{\"data\":{\"type\":\"statistics\"},\"agent_id\":\"agentid2\"}"
+  end
 end

test/receivers/receivers_test.exs

@@ -1,6 +1,8 @@
 defmodule Receivers.ReceiversTest do
   use ExUnit.Case
 
+  alias POABackend.Protocol.Message
+
   test "__using__ Receiver" do
     defmodule Receiver1 do
       use POABackend.Receiver
@@ -64,15 +66,19 @@ defmodule Receivers.ReceiversTest do
 
     {:ok, _} = Receiver2.start_link(state)
 
-    POABackend.Metric.add(:ethereum_metrics, [:message1, :message2])
-    POABackend.Metric.add(:ethereum_metrics, :message3)
+    message1 = Message.new("agentID", :ethereum_metric, :data, %{"data" => :nodata})
+    message2 = Message.new("agentID2", :ethereum_metric, :data, %{"data" => :nodata})
+    message3 = Message.new("agentID3", :ethereum_metric, :data, %{"data" => :nodata})
+
+    POABackend.Metric.add(:ethereum_metrics, [message1, message2])
+    POABackend.Metric.add(:ethereum_metrics, message3)
 
     metrics_pid = Process.whereis(:ethereum_metrics)
 
     send(metrics_pid, :nothing_happens)
 
-    assert_receive {:metric_received, :message1}, 20_000
-    assert_receive {:metric_received, :message2}, 20_000
-    assert_receive {:metric_received, :message3}, 20_000
+    assert_receive {:metric_received, ^message1}, 20_000
+    assert_receive {:metric_received, ^message2}, 20_000
+    assert_receive {:metric_received, ^message3}, 20_000
   end
 end