feat: Uses telemetry span for plug.router_dispatch (elixir-plug#1037)

Co-authored-by: Isaac Sanders <isanders@drwholdings.com>
msutkowski · Jun 19, 2021 · 8d86122 · 8d86122
1 parent bc811b4
commit 8d86122
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Showing 3 changed files with 13 additions and 29 deletions.
diff --git a/lib/plug/router.ex b/lib/plug/router.ex
@@ -243,15 +243,15 @@ defmodule Plug.Router do
 
     * `[:plug, :router_dispatch, :start]` - dispatched before dispatching to a matched route
       * Measurement: `%{system_time: System.system_time}`
-      * Metadata: `%{conn: Plug.Conn.t, route: binary, router: module}`
+      * Metadata: `%{telemetry_span_context: term(), conn: Plug.Conn.t, route: binary, router: module}`
 
     * `[:plug, :router_dispatch, :exception]` - dispatched after exceptions on dispatching a route
       * Measurement: `%{duration: native_time}`
-      * Metadata: `%{conn: Plug.Conn.t, route: binary, router: module}`
+      * Metadata: `%{telemetry_span_context: term(), conn: Plug.Conn.t, route: binary, router: module, kind: :throw | :error | :exit, reason: term(), stacktrace: list()}`
 
     * `[:plug, :router_dispatch, :stop]` - dispatched after successfully dispatching a matched route
       * Measurement: `%{duration: native_time}`
-      * Metadata: `%{conn: Plug.Conn.t, route: binary, router: module}`
+      * Metadata: `%{telemetry_span_context: term(), conn: Plug.Conn.t, route: binary, router: module}`
 
   """
 
@@ -270,35 +270,19 @@ defmodule Plug.Router do
 
       @doc false
       def dispatch(%Plug.Conn{} = conn, opts) do
-        start = System.monotonic_time()
         {path, fun} = Map.fetch!(conn.private, :plug_route)
-        metadata = %{conn: conn, route: path, router: __MODULE__}
-
-        :telemetry.execute(
-          [:plug, :router_dispatch, :start],
-          %{system_time: System.system_time()},
-          metadata
-        )
 
         try do
-          fun.(conn, opts)
-        else
-          conn ->
-            duration = System.monotonic_time() - start
-            metadata = %{metadata | conn: conn}
-            :telemetry.execute([:plug, :router_dispatch, :stop], %{duration: duration}, metadata)
-            conn
+          :telemetry.span(
+            [:plug, :router_dispatch],
+            %{conn: conn, route: path, router: __MODULE__},
+            fn ->
+              conn = fun.(conn, opts)
+              {conn, %{conn: conn, route: path, router: __MODULE__}}
+            end
+          )
         catch
           kind, reason ->
-            duration = System.monotonic_time() - start
-            metadata = %{kind: kind, reason: reason, stacktrace: __STACKTRACE__}
-
-            :telemetry.execute(
-              [:plug, :router_dispatch, :exception],
-              %{duration: duration},
-              metadata
-            )
-
             Plug.Conn.WrapperError.reraise(conn, kind, reason, __STACKTRACE__)
         end
       end

diff --git a/mix.exs b/mix.exs
@@ -43,7 +43,7 @@ defmodule Plug.MixProject do
     [
       {:mime, "~> 1.0"},
       {:plug_crypto, "~> 1.1.1 or ~> 1.2"},
-      {:telemetry, "~> 0.4"},
+      {:telemetry, ">= 0.4.3 and < 1.0.0"},
       {:ex_doc, "~> 0.21", only: :docs}
     ]
   end

diff --git a/mix.lock b/mix.lock
@@ -6,5 +6,5 @@
   "mime": {:hex, :mime, "1.6.0", "dabde576a497cef4bbdd60aceee8160e02a6c89250d6c0b29e56c0dfb00db3d2", [:mix], [], "hexpm", "31a1a8613f8321143dde1dafc36006a17d28d02bdfecb9e95a880fa7aabd19a7"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.1.0", "3a6fca1550363552e54c216debb6a9e95bd8d32348938e13de5eda962c0d7f89", [:mix], [], "hexpm", "08eb32d66b706e913ff748f11694b17981c0b04a33ef470e33e11b3d3ac8f54b"},
   "plug_crypto": {:hex, :plug_crypto, "1.2.1", "5c854427528bf61d159855cedddffc0625e2228b5f30eff76d5a4de42d896ef4", [:mix], [], "hexpm", "6961c0e17febd9d0bfa89632d391d2545d2e0eb73768f5f50305a23961d8782c"},
-  "telemetry": {:hex, :telemetry, "0.4.0", "8339bee3fa8b91cb84d14c2935f8ecf399ccd87301ad6da6b71c09553834b2ab", [:rebar3], [], "hexpm", "e9e3cacfd37c1531c0ca70ca7c0c30ce2dbb02998a4f7719de180fe63f8d41e4"},
+  "telemetry": {:hex, :telemetry, "0.4.3", "a06428a514bdbc63293cd9a6263aad00ddeb66f608163bdec7c8995784080818", [:rebar3], [], "hexpm", "eb72b8365ffda5bed68a620d1da88525e326cb82a75ee61354fc24b844768041"},
 }