From e29ddfaabaad95b436d6680c0466a5cded192e4f Mon Sep 17 00:00:00 2001
From: Radek Szymczyszyn <radoslaw.szymczyszyn@erlang-solutions.com>
Date: Thu, 4 Jul 2024 12:21:56 +0200
Subject: [PATCH] Catch throws, stringify thrown values and exit reasons for
 reporting

---
 lib/open_telemetry_decorator.ex        | 11 +++++++--
 test/open_telemetry_decorator_test.exs | 33 +++++++++++++++++++++-----
 2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/lib/open_telemetry_decorator.ex b/lib/open_telemetry_decorator.ex
index 4a6b240..eedfe27 100644
--- a/lib/open_telemetry_decorator.ex
+++ b/lib/open_telemetry_decorator.ex
@@ -90,11 +90,18 @@ defmodule OpenTelemetryDecorator do
           O11y.set_attribute(:exit, :shutdown, namespace: prefix)
 
         :exit, {:shutdown, reason} ->
-          O11y.set_attributes([exit: :shutdown, shutdown_reason: reason], namespace: prefix)
+          O11y.set_attributes(
+            [exit: :shutdown, shutdown_reason: inspect(reason)],
+            namespace: prefix
+          )
 
         :exit, reason ->
-          O11y.set_error("exited: #{reason}")
+          O11y.set_error("exited: #{inspect(reason)}")
           :erlang.raise(:exit, reason, __STACKTRACE__)
+
+        :throw, thrown ->
+          O11y.set_error("uncaught: #{inspect(thrown)}")
+          :erlang.raise(:throw, thrown, __STACKTRACE__)
       after
         O11y.end_span(parent_span)
       end
diff --git a/test/open_telemetry_decorator_test.exs b/test/open_telemetry_decorator_test.exs
index 34ba466..cbbda17 100644
--- a/test/open_telemetry_decorator_test.exs
+++ b/test/open_telemetry_decorator_test.exs
@@ -74,6 +74,11 @@ defmodule OpenTelemetryDecoratorTest do
         exit(exit_args)
       end
 
+      @decorate with_span("Example.with_throw")
+      def with_throw(throw_args) do
+        throw(throw_args)
+      end
+
       @decorate with_span("Example.with_error")
       def with_error, do: Attributes.set(:error, "ruh roh!")
 
@@ -230,15 +235,15 @@ defmodule OpenTelemetryDecoratorTest do
       end
     end
 
-    test "catches exists, sets errors, and re-throws" do
+    test "catches exits, sets errors, and re-throws" do
       try do
-        Example.with_exit(:bad_times)
+        Example.with_exit(%{bad: :times})
         flunk("Should have re-raised the exception")
       catch
-        :exit, :bad_times ->
+        :exit, %{bad: :times} ->
           span = assert_span("Example.with_exit")
           assert span.status.code == :error
-          assert span.status.message == "exited: bad_times"
+          assert span.status.message == "exited: %{bad: :times}"
       end
     end
 
@@ -276,9 +281,25 @@ defmodule OpenTelemetryDecoratorTest do
     end
 
     test "shutdowns with a reason add exit and shutdown_reason attributes" do
-      Example.with_exit({:shutdown, :chillin})
+      Example.with_exit({:shutdown, %{just: :chillin}})
       span = assert_span("Example.with_exit")
-      assert span.attributes == %{"app.exit" => :shutdown, "app.shutdown_reason" => :chillin}
+
+      assert span.attributes == %{
+               "app.exit" => :shutdown,
+               "app.shutdown_reason" => "%{just: :chillin}"
+             }
+    end
+
+    test "catches throws, sets errors, and re-throws" do
+      try do
+        Example.with_throw(%{catch: :this})
+        flunk("Should have re-raised the exception")
+      catch
+        :throw, %{catch: :this} ->
+          span = assert_span("Example.with_throw")
+          assert span.status.code == :error
+          assert span.status.message == "uncaught: %{catch: :this}"
+      end
     end
 
     test "adds included input params on exception" do