First pass at custom viewing metrics for simple count history, and wo…

…rking!

lib/companies/application.ex

@@ -12,6 +12,7 @@ defmodule Companies.Application do
       Companies.Repo,
       CompaniesWeb.Telemetry,
       CompaniesWeb.RepoMetricsHistory,
+      CompaniesWeb.ViewingStats,
       # Start the PubSub system
       {Phoenix.PubSub, name: Companies.PubSub},
       # Start the endpoint when the application starts
@@ -27,6 +28,7 @@ defmodule Companies.Application do
     )
 
     CompaniesWeb.RepoMetricsHistory.setup_handlers()
+    CompaniesWeb.ViewingStats.setup_handlers()
 
     # See https://hexdocs.pm/elixir/Supervisor.html
     # for other strategies and supported options

lib/companies_web/controllers/company_controller.ex

@@ -2,6 +2,7 @@ defmodule CompaniesWeb.CompanyController do
   use CompaniesWeb, :controller
 
   alias Companies.{Companies, Industries, Schema.Company}
+  import CompaniesWeb.ViewingStats, only: [telemetry_event: 0]
 
   def recent(conn, _params) do
     companies_count = Companies.count()
@@ -13,6 +14,7 @@ defmodule CompaniesWeb.CompanyController do
   def index(conn, params) do
     companies = Companies.all(params)
     industries = Industries.for_select()
+    :telemetry.execute(telemetry_event(), %{company_index: 1})
 
     render(conn, "index.html", companies: companies, industries: industries)
   end
@@ -39,6 +41,7 @@ defmodule CompaniesWeb.CompanyController do
 
   def show(conn, %{"id" => id}) do
     company = Companies.get!(id, preloads: [:jobs, :industry])
+    :telemetry.execute(telemetry_event(), %{company_show: 1})
     render(conn, "show.html", company: company)
   end
 

lib/companies_web/historical_data.ex

@@ -0,0 +1,9 @@
+defmodule CompaniesWeb.HistoricalData do
+  alias CompaniesWeb.{RepoMetricsHistory, ViewingStats}
+
+  def signatures do
+    for module <- [RepoMetricsHistory, ViewingStats], reduce: %{} do
+      acc -> Map.merge(acc, apply(module, :signatures, []))
+    end
+  end
+end

lib/companies_web/repo_metrics_history.ex

@@ -31,7 +31,7 @@ defmodule CompaniesWeb.RepoMetricsHistory do
 
   def setup_handlers do
     :telemetry.attach(
-      "aggregation-handler-generic",
+      "aggregation-handler-#{__MODULE__}",
       @telemetry_event,
       &__MODULE__.handle_event/4,
       nil

lib/companies_web/router.ex

@@ -41,7 +41,7 @@ defmodule CompaniesWeb.Router do
 
     live_dashboard "/",
       metrics: CompaniesWeb.Telemetry,
-      historical_data: CompaniesWeb.RepoMetricsHistory.signatures()
+      historical_data: CompaniesWeb.HistoricalData.signatures()
   end
 
   scope "/", CompaniesWeb do

lib/companies_web/telemetry.ex

@@ -43,6 +43,12 @@ defmodule CompaniesWeb.Telemetry do
       summary("ecto.dashboard.query.queue_time", unit: {:native, :millisecond}),
       summary("ecto.dashboard.query.idle_time", unit: {:native, :millisecond}),
 
+      # Page view stats
+      summary("page_views.companies_web.company_index"),
+      summary("page_views.companies_web.company_show"),
+      summary("page_views.companies_web.job_index"),
+      summary("page_views.companies_web.job_show"),
+
       # VM Metrics
       summary("vm.memory.total", unit: {:byte, :kilobyte}),
       summary("vm.total_run_queue_lengths.total"),
@@ -52,6 +58,6 @@ defmodule CompaniesWeb.Telemetry do
   end
 
   defp periodic_measurements do
-    []
+    [{CompaniesWeb.ViewingStats, :emit, []}]
   end
 end

lib/companies_web/viewing_stats.ex

@@ -0,0 +1,83 @@
+defmodule CompaniesWeb.ViewingStats do
+  use GenServer
+
+  @telemetry_event [:page_views, :count_events]
+  @historic_metrics [:page_views, :companies_web]
+  @history_buffer_size 500
+
+  def signatures do
+    %{
+      @historic_metrics => {__MODULE__, :data, []}
+    }
+  end
+
+  def telemetry_event, do: @telemetry_event
+
+  def start_link([]) do
+    GenServer.start_link(__MODULE__, %{}, name: __MODULE__)
+  end
+
+  def init(_state) do
+    {:ok, %{history: CircularBuffer.new(@history_buffer_size), current: %{}}}
+  end
+
+  def data(%{event_name: event_name} = metric) do
+    if List.starts_with?(event_name, @historic_metrics) do
+      GenServer.call(__MODULE__, {:data, metric})
+    else
+      []
+    end
+  end
+
+  def setup_handlers do
+    :telemetry.attach(
+      "aggregation-handler-#{__MODULE__}",
+      @telemetry_event,
+      &__MODULE__.handle_event/4,
+      nil
+    )
+  end
+
+  def handle_event(@telemetry_event, map, metadata, config) do
+    GenServer.cast(__MODULE__, {:telemetry_metric, map, metadata, config})
+  end
+
+  def emit do
+    GenServer.cast(__MODULE__, :emit_telemetry)
+  end
+
+  def handle_call({:raw_data, _metric}, _from, %{history: history} = state) do
+    {:reply, history, state}
+  end
+
+  def handle_call({:data, metric}, _from, %{history: history} = state) do
+    local_metric = List.last(metric.name)
+
+    reply =
+      for {time, time_metrics} <- history,
+          {^local_metric, data} <- time_metrics do
+        %{data: %{local_metric => data}, time: time}
+      end
+
+    {:reply, reply, state}
+  end
+
+  def handle_cast(:emit_telemetry, %{history: history, current: current}) do
+    time = System.system_time(:second)
+
+    for {key, value} <- current do
+      :telemetry.execute(@historic_metrics, %{key => value})
+    end
+
+    {:noreply, %{history: CircularBuffer.insert(history, {time, current}), current: %{}}}
+  end
+
+  def handle_cast({:telemetry_metric, metric_map, _metadata, _config}, %{current: current} = state) do
+    updated_current =
+      for {key, value} <- metric_map, reduce: current do
+        acc -> Map.put_new(acc, key, 0) |> update_in([key], &(&1 + value))
+      end
+
+    {:noreply, %{state | current: updated_current}}
+  end
+end

mix.lock

@@ -36,7 +36,7 @@
   "phoenix": {:hex, :phoenix, "1.5.1", "95156589879dc69201d5fc0ebdbfdfc7901a09a3616ea611ec297f81340275a2", [:mix], [{:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:phoenix_html, "~> 2.13", [hex: :phoenix_html, repo: "hexpm", optional: true]}, {:phoenix_pubsub, "~> 2.0", [hex: :phoenix_pubsub, repo: "hexpm", optional: false]}, {:plug, "~> 1.10", [hex: :plug, repo: "hexpm", optional: false]}, {:plug_cowboy, "~> 1.0 or ~> 2.2", [hex: :plug_cowboy, repo: "hexpm", optional: true]}, {:plug_crypto, "~> 1.1.2 or ~> 1.2", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "fc272b38e79d2881790fccae6f67a9fbe9b790103d6878175ea03d23003152eb"},
   "phoenix_ecto": {:hex, :phoenix_ecto, "4.1.0", "a044d0756d0464c5a541b4a0bf4bcaf89bffcaf92468862408290682c73ae50d", [:mix], [{:ecto, "~> 3.0", [hex: :ecto, repo: "hexpm", optional: false]}, {:phoenix_html, "~> 2.9", [hex: :phoenix_html, repo: "hexpm", optional: true]}, {:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "c5e666a341ff104d0399d8f0e4ff094559b2fde13a5985d4cb5023b2c2ac558b"},
   "phoenix_html": {:hex, :phoenix_html, "2.14.2", "b8a3899a72050f3f48a36430da507dd99caf0ac2d06c77529b1646964f3d563e", [:mix], [{:plug, "~> 1.5", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "58061c8dfd25da5df1ea0ca47c972f161beb6c875cd293917045b92ffe1bf617"},
-  "phoenix_live_dashboard": {:git, "https://github.com/bglusman/phoenix_live_dashboard.git", "3f10c91457cf4c5e538f40086cd7ce0b318954e8", [branch: "historical_data"]},
+  "phoenix_live_dashboard": {:git, "https://github.com/bglusman/phoenix_live_dashboard.git", "9259f4480c8114099bda8ec5d9bda070aad06d02", [branch: "historical_data"]},
   "phoenix_live_reload": {:hex, :phoenix_live_reload, "1.2.1", "274a4b07c4adbdd7785d45a8b0bb57634d0b4f45b18d2c508b26c0344bd59b8f", [:mix], [{:file_system, "~> 0.2.1 or ~> 0.3", [hex: :file_system, repo: "hexpm", optional: false]}, {:phoenix, "~> 1.4", [hex: :phoenix, repo: "hexpm", optional: false]}], "hexpm", "41b4103a2fa282cfd747d377233baf213c648fdcc7928f432937676532490eee"},
   "phoenix_live_view": {:hex, :phoenix_live_view, "0.12.1", "42f591c781edbf9fab921319076b7ac635d43aa23e6748d2644563326236d7e4", [:mix], [{:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:phoenix, "~> 1.4.16 or ~> 1.5.0", [hex: :phoenix, repo: "hexpm", optional: false]}, {:phoenix_html, "~> 2.14", [hex: :phoenix_html, repo: "hexpm", optional: false]}], "hexpm", "585321e98df1cd5943e370b9784e950a37ca073744eb534660c9048967c52ab6"},
   "phoenix_pubsub": {:hex, :phoenix_pubsub, "2.0.0", "a1ae76717bb168cdeb10ec9d92d1480fec99e3080f011402c0a2d68d47395ffb", [:mix], [], "hexpm", "c52d948c4f261577b9c6fa804be91884b381a7f8f18450c5045975435350f771"},