Add telemetry to api server

lib/spandex_datadog/api_server.ex

@@ -106,8 +106,11 @@ defmodule SpandexDatadog.ApiServer do
   """
   @spec send_trace(Trace.t(), Keyword.t()) :: :ok
   def send_trace(%Trace{} = trace, opts \\ []) do
-    timeout = Keyword.get(opts, :timeout, 30_000)
-    GenServer.call(__MODULE__, {:send_trace, trace}, timeout)
+    :telemetry.span([:spandex_datadog, :send_trace], %{trace: trace}, fn ->
+      timeout = Keyword.get(opts, :timeout, 30_000)
+      result = GenServer.call(__MODULE__, {:send_trace, trace}, timeout)
+      {result, %{result: result}}
+    end)
   end
 
   @deprecated "Please use send_trace/2 instead"
@@ -144,47 +147,51 @@ defmodule SpandexDatadog.ApiServer do
           agent_pid: agent_pid
         } = state
       ) do
-    all_traces = [trace | waiting_traces]
+    :telemetry.span([:spandex_datadog, :handle_call, :send_trace], %{trace: trace, state: state}, fn ->
+      all_traces = [trace | waiting_traces]
 
-    if verbose? do
-      trace_count = length(all_traces)
+      if verbose? do
+        trace_count = length(all_traces)
 
-      span_count = Enum.reduce(all_traces, 0, fn trace, acc -> acc + length(trace.spans) end)
+        span_count = Enum.reduce(all_traces, 0, fn trace, acc -> acc + length(trace.spans) end)
 
-      Logger.info(fn -> "Sending #{trace_count} traces, #{span_count} spans." end)
+        Logger.info(fn -> "Sending #{trace_count} traces, #{span_count} spans." end)
 
-      Logger.debug(fn -> "Trace: #{inspect(all_traces)}" end)
-    end
+        Logger.debug(fn -> "Trace: #{inspect(all_traces)}" end)
+      end
 
-    if asynchronous? do
-      below_sync_threshold? =
-        Agent.get_and_update(agent_pid, fn count ->
-          if count < sync_threshold do
-            {true, count + 1}
-          else
-            {false, count}
-          end
-        end)
-
-      if below_sync_threshold? do
-        Task.start(fn ->
-          try do
-            send_and_log(all_traces, state)
-          after
-            Agent.update(agent_pid, fn count -> count - 1 end)
-          end
-        end)
+      if asynchronous? do
+        below_sync_threshold? =
+          Agent.get_and_update(agent_pid, fn count ->
+            if count < sync_threshold do
+              {true, count + 1}
+            else
+              {false, count}
+            end
+          end)
+
+        if below_sync_threshold? do
+          Task.start(fn ->
+            try do
+              send_and_log(all_traces, state)
+            after
+              Agent.update(agent_pid, fn count -> count - 1 end)
+            end
+          end)
+        else
+          # We get benefits from running in a separate process (like better GC)
+          # So we async/await here to mimic the behavour above but still apply backpressure
+          task = Task.async(fn -> send_and_log(all_traces, state) end)
+          Task.await(task)
+        end
       else
-        # We get benefits from running in a separate process (like better GC)
-        # So we async/await here to mimic the behavour above but still apply backpressure
-        task = Task.async(fn -> send_and_log(all_traces, state) end)
-        Task.await(task)
+        send_and_log(all_traces, state)
       end
-    else
-      send_and_log(all_traces, state)
-    end
 
-    {:reply, :ok, %{state | waiting_traces: []}}
+      state = %{state | waiting_traces: []}
+
+      {{:reply, :ok, state}, %{state: state}}
+    end)
   end
 
   @spec send_and_log([Trace.t()], State.t()) :: :ok

mix.exs

@@ -62,6 +62,7 @@ defmodule SpandexDatadog.MixProject do
       {:git_ops, "~> 2.0", only: [:dev]},
       {:inch_ex, "~> 2.0", only: [:dev, :test]},
       {:spandex, "~> 3.0"},
+      {:telemetry, "~> 0.4"},
       {:httpoison, "~> 0.13", only: :test},
       {:msgpax, "~> 2.2.1"}
     ]

mix.lock

@@ -24,5 +24,6 @@
   "plug_crypto": {:hex, :plug_crypto, "1.1.2", "bdd187572cc26dbd95b87136290425f2b580a116d3fb1f564216918c9730d227", [:mix], [], "hexpm", "6b8b608f895b6ffcfad49c37c7883e8df98ae19c6a28113b02aa1e9c5b22d6b5"},
   "spandex": {:hex, :spandex, "3.0.1", "1979e96372cef16dd7a9b079da5b21647d6d7f2d3e6aa544d9ce5638e9350cb5", [:mix], [{:decorator, "~> 1.2", [hex: :decorator, repo: "hexpm", optional: true]}, {:optimal, "~> 0.3.3", [hex: :optimal, repo: "hexpm", optional: false]}, {:plug, ">= 1.0.0", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm", "22a5046b67d751cf4bbebf1ee23d977d8e05ad750ea578070ba6e5b293b64ff2"},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.4", "f0eafff810d2041e93f915ef59899c923f4568f4585904d010387ed74988e77b", [:make, :mix, :rebar3], [], "hexpm", "603561dc0fd62f4f2ea9b890f4e20e1a0d388746d6e20557cafb1b16950de88c"},
+  "telemetry": {:hex, :telemetry, "0.4.2", "2808c992455e08d6177322f14d3bdb6b625fbcfd233a73505870d8738a2f4599", [:rebar3], [], "hexpm", "2d1419bd9dda6a206d7b5852179511722e2b18812310d304620c7bd92a13fcef"},
   "unicode_util_compat": {:hex, :unicode_util_compat, "0.4.1", "d869e4c68901dd9531385bb0c8c40444ebf624e60b6962d95952775cac5e90cd", [:rebar3], [], "hexpm", "1d1848c40487cdb0b30e8ed975e34e025860c02e419cb615d255849f3427439d"},
 }