Merge pull request #138 from gugahoa/add-record-exception

Add RecordException to Elixir's Span module

Author: tsloughter

apps/opentelemetry/test/opentelemetry_SUITE.erl

@@ -19,7 +19,7 @@ all() ->
 all_testcases() ->
     [with_span, macros, child_spans, update_span_data, tracer_instrumentation_library,
      tracer_previous_ctx, stop_temporary_app, reset_after, attach_ctx, default_sampler,
-     record_but_not_sample].
+     record_but_not_sample, record_exception_works, record_exception_with_message_works].
 
 groups() ->
     [{w3c, [], [propagation]},
@@ -456,6 +456,47 @@ record_but_not_sample(Config) ->
 
     ok.
 
+record_exception_works(Config) ->
+    Tid = ?config(tid, Config),
+    SpanCtx = ?start_span(<<"span-1">>),
+    try throw(my_error) of
+        _ ->
+        ok
+    catch
+        Class:Term:Stacktrace ->
+            otel_span:record_exception(SpanCtx, Class, Term, Stacktrace, [{"some-attribute", "value"}]),
+            ?end_span(SpanCtx),
+            [Span] = assert_exported(Tid, SpanCtx),
+            [Event] = Span#span.events,
+            ?assertEqual(<<"exception">>, Event#event.name),
+            ?assertEqual([{<<"exception.type">>, <<"throw:my_error">>},
+                          {<<"exception.stacktrace">>, list_to_binary(io_lib:format("~p", [Stacktrace], [{chars_limit, 50}]))},
+                          {"some-attribute","value"}],
+                         Event#event.attributes),
+            ok
+    end.
+
+record_exception_with_message_works(Config) ->
+    Tid = ?config(tid, Config),
+    SpanCtx = ?start_span(<<"span-1">>),
+    try throw(my_error) of
+        _ ->
+        ok
+    catch
+        Class:Term:Stacktrace ->
+            otel_span:record_exception(SpanCtx, Class, Term, "My message", Stacktrace, [{"some-attribute", "value"}]),
+            ?end_span(SpanCtx),
+            [Span] = assert_exported(Tid, SpanCtx),
+            [Event] = Span#span.events,
+            ?assertEqual(<<"exception">>, Event#event.name),
+            ?assertEqual([{<<"exception.type">>, <<"throw:my_error">>},
+                          {<<"exception.stacktrace">>, list_to_binary(io_lib:format("~p", [Stacktrace], [{chars_limit, 50}]))},
+                          {<<"exception.message">>, "My message"},
+                          {"some-attribute","value"}],
+                         Event#event.attributes),
+            ok
+    end.
+
 %%
 
 assert_all_exported(Tid, SpanCtxs) ->

apps/opentelemetry_api/lib/open_telemetry/span.ex

@@ -95,6 +95,34 @@ defmodule OpenTelemetry.Span do
   @spec add_events(OpenTelemetry.span_ctx(), [OpenTelemetry.event()]) :: boolean()
   defdelegate add_events(span_ctx, events), to: :otel_span
 
+  defguardp is_exception?(term)
+            when is_map(term) and :erlang.is_map_key(:__struct__, term) and
+                   is_atom(:erlang.map_get(:__struct__, term)) and
+                   :erlang.is_map_key(:__exception__, term) and
+                   :erlang.map_get(:__exception__, term) == true
+
+  @doc """
+  Record an exception as an event, following the semantics convetions for exceptions.
+
+  If trace is not provided, the stacktrace is retrieved from `Process.info/2`
+  """
+  @spec record_exception(OpenTelemetry.span_ctx(), Exception.t()) :: boolean()
+  def record_exception(span_ctx, exception, trace \\ nil, attributes \\ [])
+
+  def record_exception(span_ctx, exception, trace, attributes) when is_exception?(exception) do
+    exception_type = to_string(exception.__struct__)
+
+    exception_attributes = [
+      {"exception.type", exception_type},
+      {"exception.message", Exception.message(exception)},
+      {"exception.stacktrace", Exception.format_stacktrace(trace)}
+    ]
+
+    add_event(span_ctx, "exception", exception_attributes ++ attributes)
+  end
+
+  def record_exception(_, _, _, _), do: false
+
   @doc """
   Sets the Status of the currently active Span.
 

apps/opentelemetry_api/src/otel_span.erl

@@ -27,6 +27,8 @@
          set_attributes/2,
          add_event/3,
          add_events/2,
+         record_exception/5,
+         record_exception/6,
          set_status/2,
          update_name/2,
          end_span/1]).
@@ -105,6 +107,30 @@ add_events(SpanCtx=#span_ctx{span_sdk={Module, _}}, Events) when ?is_recording(S
 add_events(_, _) ->
     false.
 
+-spec record_exception(SpanCtx, Class, Term, Stacktrace, Attributes) -> boolean() when
+      SpanCtx :: opentelemetry:span_ctx(),
+      Class :: atom(),
+      Term :: term(),
+      Stacktrace :: list(any()),
+      Attributes :: opentelemetry:attributes().
+record_exception(SpanCtx, Class, Term, Stacktrace, Attributes) ->
+    ExceptionAttributes = [{<<"exception.type">>, iolist_to_binary(io_lib:format("~0tP:~0tP", [Class, 10, Term, 10], [{chars_limit, 50}]))},
+                           {<<"exception.stacktrace">>, iolist_to_binary(io_lib:format("~0tP", [Stacktrace, 10], [{chars_limit, 50}]))}],
+    add_event(SpanCtx, <<"exception">>, ExceptionAttributes ++ Attributes).
+
+-spec record_exception(SpanCtx, Class, Term,  Message, Stacktrace, Attributes) -> boolean() when
+      SpanCtx :: opentelemetry:span_ctx(),
+      Class :: atom(),
+      Term :: term(),
+      Message :: unicode:unicode_binary(),
+      Stacktrace :: list(any()),
+      Attributes :: opentelemetry:attributes().
+record_exception(SpanCtx, Class, Term, Message, Stacktrace, Attributes) ->
+    ExceptionAttributes = [{<<"exception.type">>, iolist_to_binary(io_lib:format("~0tP:~0tP", [Class, 10, Term, 10], [{chars_limit, 50}]))},
+                           {<<"exception.stacktrace">>, iolist_to_binary(io_lib:format("~0tP", [Stacktrace, 10], [{chars_limit, 50}]))},
+                           {<<"exception.message">>, Message}],
+    add_event(SpanCtx, <<"exception">>, ExceptionAttributes ++ Attributes).
+
 -spec set_status(SpanCtx, Status) -> boolean() when
       Status :: opentelemetry:status(),
       SpanCtx :: opentelemetry:span_ctx().

test/otel_tests.exs

@@ -8,9 +8,13 @@ defmodule OtelTests do
   require Record
   @fields Record.extract(:span, from_lib: "opentelemetry/include/otel_span.hrl")
   Record.defrecordp(:span, @fields)
+
   @fields Record.extract(:span_ctx, from_lib: "opentelemetry_api/include/opentelemetry.hrl")
   Record.defrecordp(:span_ctx, @fields)
 
+  @event_fields Record.extract(:event, from_lib: "opentelemetry_api/include/opentelemetry.hrl")
+  Record.defrecordp(:event, @event_fields)
+
   test "use Tracer to set current active Span's attributes" do
     :otel_batch_processor.set_exporter(:otel_exporter_pid, self())
     OpenTelemetry.register_tracer(:test_tracer, "0.1.0")
@@ -200,4 +204,40 @@ defmodule OtelTests do
                       parent_span_id: :undefined
                     )}
   end
+
+  test "Span.record_exception/4 should return false if passed an invalid exception" do
+    Tracer.with_span "span-3" do
+      refute OpenTelemetry.Span.record_exception(Tracer.current_span_ctx(), :not_an_exception)
+    end
+  end
+
+  test "Span.record_exception/4 should add an exception event to the span" do
+    :otel_batch_processor.set_exporter(:otel_exporter_pid, self())
+    s = Tracer.start_span("span-4")
+
+    try do
+      raise RuntimeError, "my error message"
+    rescue
+      ex ->
+        assert Span.record_exception(s, ex, __STACKTRACE__)
+        assert Span.end_span(s)
+
+        stacktrace = Exception.format_stacktrace(__STACKTRACE__)
+
+        assert_receive {:span,
+                        span(
+                          name: "span-4",
+                          events: [
+                            event(
+                              name: "exception",
+                              attributes: [
+                                {"exception.type", "Elixir.RuntimeError"},
+                                {"exception.message", "my error message"},
+                                {"exception.stacktrace", ^stacktrace}
+                              ]
+                            )
+                          ]
+                        )}
+    end
+  end
 end