From f5eb6655ea5fa2d36c6d4146f42cfe636421cd47 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Mon, 8 Aug 2022 20:10:46 -0500
Subject: [PATCH 01/44] Handle optional sampling priority as nil; handle
 optional origin header

---
 lib/spandex_datadog/adapter.ex | 150 ++++++++++++++++++++-------------
 test/adapter_test.exs          |  35 ++++++--
 2 files changed, 121 insertions(+), 64 deletions(-)

diff --git a/lib/spandex_datadog/adapter.ex b/lib/spandex_datadog/adapter.ex
index 00a64ec..98a138f 100644
--- a/lib/spandex_datadog/adapter.ex
+++ b/lib/spandex_datadog/adapter.ex
@@ -33,91 +33,123 @@ defmodule SpandexDatadog.Adapter do
   Fetches the Datadog-specific conn request headers if they are present.
   """
   @impl Spandex.Adapter
-  @spec distributed_context(conn :: Plug.Conn.t(), Tracer.opts()) ::
-          {:ok, SpanContext.t()}
-          | {:error, :no_distributed_trace}
-  def distributed_context(%Plug.Conn{} = conn, _opts) do
-    trace_id = get_first_header(conn, "x-datadog-trace-id")
-    parent_id = get_first_header(conn, "x-datadog-parent-id")
-    priority = get_first_header(conn, "x-datadog-sampling-priority") || 1
-
-    if is_nil(trace_id) || is_nil(parent_id) do
-      {:error, :no_distributed_trace}
-    else
-      {:ok, %SpanContext{trace_id: trace_id, parent_id: parent_id, priority: priority}}
-    end
+  @spec distributed_context(Plug.Conn.t(), Tracer.opts()) ::
+          {:ok, SpanContext.t()} | {:error, :no_distributed_trace}
+  def distributed_context(%Plug.Conn{req_headers: headers}, opts) do
+    distributed_context(headers, opts)
   end
 
   @impl Spandex.Adapter
-  @spec distributed_context(headers :: Spandex.headers(), Tracer.opts()) ::
-          {:ok, SpanContext.t()}
-          | {:error, :no_distributed_trace}
+  @spec distributed_context(Spandex.headers(), Tracer.opts()) ::
+          {:ok, SpanContext.t()} | {:error, :no_distributed_trace}
   def distributed_context(headers, _opts) do
-    trace_id = get_header(headers, "x-datadog-trace-id")
-    parent_id = get_header(headers, "x-datadog-parent-id")
-    priority = get_header(headers, "x-datadog-sampling-priority") || 1
-
-    if is_nil(trace_id) || is_nil(parent_id) do
-      {:error, :no_distributed_trace}
-    else
-      {:ok, %SpanContext{trace_id: trace_id, parent_id: parent_id, priority: priority}}
-    end
+    headers
+    |> Enum.reduce(%SpanContext{}, &extract_header/2)
+    |> validate_context()
   end
 
   @doc """
   Injects Datadog-specific HTTP headers to represent the specified SpanContext
   """
   @impl Spandex.Adapter
-  @spec inject_context([{term(), term()}], SpanContext.t(), Tracer.opts()) :: [{term(), term()}]
-  def inject_context(headers, %SpanContext{} = span_context, _opts) when is_list(headers) do
-    span_context
-    |> tracing_headers()
-    |> Kernel.++(headers)
+  @spec inject_context(Spandex.headers(), SpanContext.t(), Tracer.opts()) :: Spandex.headers()
+  def inject_context(headers, %SpanContext{} = span_context, opts) when is_map(headers) do
+    inject_context(Map.to_list(headers), span_context, opts) |> Enum.into(%{})
   end
 
-  def inject_context(headers, %SpanContext{} = span_context, _opts) when is_map(headers) do
+  def inject_context(headers, %SpanContext{} = span_context, _opts) when is_list(headers) do
     span_context
-    |> tracing_headers()
-    |> Enum.into(%{})
-    |> Map.merge(headers)
+    |> Map.from_struct()
+    |> Enum.reject(fn {_, value} -> is_nil(value) end)
+    |> Enum.reduce([], &inject_header/2)
+    |> Enum.concat(headers)
   end
 
   # Private Helpers
 
-  @spec get_first_header(Plug.Conn.t(), String.t()) :: integer() | nil
-  defp get_first_header(conn, header_name) do
-    conn
-    |> Plug.Conn.get_req_header(header_name)
-    |> List.first()
-    |> parse_header()
+  # Reduce function that sets values in SpanContext for headers
+  @spec extract_header({binary(), binary()}, SpanContext.t()) :: SpanContext.t()
+  defp extract_header({"x-datadog-trace-id", value}, span_context) do
+    put_context_int(span_context, :trace_id, value)
+  end
+
+  defp extract_header({"x-datadog-parent-id", value}, span_context) do
+    put_context_int(span_context, :parent_id, value)
   end
 
-  @spec get_header(%{}, String.t()) :: integer() | nil
-  defp get_header(headers, key) when is_map(headers) do
-    Map.get(headers, key, nil)
-    |> parse_header()
+  defp extract_header({"x-datadog-sampling-priority", value}, span_context) do
+    put_context_int(span_context, :priority, value)
   end
 
-  @spec get_header([], String.t()) :: integer() | nil
-  defp get_header(headers, key) when is_list(headers) do
-    Enum.find_value(headers, fn {k, v} -> if k == key, do: v end)
-    |> parse_header()
+  defp extract_header({"x-datadog-origin", value}, span_context) do
+    %{span_context | baggage: span_context.baggage ++ [{"_dd.origin", value}]}
   end
 
-  defp parse_header(header) when is_bitstring(header) do
-    case Integer.parse(header) do
-      {int, _} -> int
-      _ -> nil
+  # Update context with value if it is an integer
+  @spec put_context_int(Spandex.SpanContext.t(), atom(), binary()) :: Spandex.SpanContext.t()
+  defp put_context_int(span_context, key, value) do
+    case Integer.parse(value) do
+      {int_value, _} ->
+        Map.put(span_context, key, int_value)
+
+      _ ->
+        span_context
+    end
+  end
+
+  # Determine if SpanContext is valid
+  @spec validate_context(SpanContext.t()) ::
+          {:ok, SpanContext.t()} | {:error, :no_distributed_trace}
+  defp validate_context(%{trace_id: nil}) do
+    {:error, :no_distributed_trace}
+  end
+
+  # Based on the code of the Ruby libary, it seems valid
+  # to have onlly the trace_id and origin headers set, but not parent_id.
+  # This might happen with RUM or synthetic traces.
+  defp validate_context(%{parent_id: nil} = span_context) do
+    case :proplists.get_value("_dd.origin", span_context.baggage) do
+      :undefined ->
+        {:error, :no_distributed_trace}
+
+      _ ->
+        {:ok, span_context}
     end
   end
 
-  defp parse_header(_header), do: nil
+  defp validate_context(span_context) do
+    {:ok, span_context}
+  end
+
+  # Add SpanContext value to headers
+  @spec inject_header({atom(), term()}, [{binary(), binary()}]) :: [{binary(), binary()}]
+  defp inject_header({:baggage, []}, headers) do
+    headers
+  end
+
+  defp inject_header({:baggage, baggage}, headers) do
+    case :proplists.get_value("_dd.origin", baggage) do
+      :undefined ->
+        headers
+
+      value ->
+        [{"x-datadog-origin", value} | headers]
+    end
+  end
+
+  defp inject_header({:trace_id, value}, headers) do
+    [{"x-datadog-trace-id", to_string(value)} | headers]
+  end
+
+  defp inject_header({:parent_id, value}, headers) do
+    [{"x-datadog-parent-id", to_string(value)} | headers]
+  end
+
+  defp inject_header({:priority, value}, headers) do
+    [{"x-datadog-sampling-priority", to_string(value)} | headers]
+  end
 
-  defp tracing_headers(%SpanContext{trace_id: trace_id, parent_id: parent_id, priority: priority}) do
-    [
-      {"x-datadog-trace-id", to_string(trace_id)},
-      {"x-datadog-parent-id", to_string(parent_id)},
-      {"x-datadog-sampling-priority", to_string(priority)}
-    ]
+  defp inject_header(_, headers) do
+    headers
   end
 end
diff --git a/test/adapter_test.exs b/test/adapter_test.exs
index 93fde23..36d64fe 100644
--- a/test/adapter_test.exs
+++ b/test/adapter_test.exs
@@ -88,14 +88,26 @@ defmodule SpandexDatadog.Test.AdapterTest do
       assert span_context.priority == 2
     end
 
-    test "priority defaults to 1 (i.e. we currently assume all distributed traces should be kept)" do
+    test "returns a SpanContext struct when only x-datadog-trace-id and x-datadog-origin are set" do
+      conn =
+        :get
+        |> Plug.Test.conn("/")
+        |> Plug.Conn.put_req_header("x-datadog-trace-id", "123")
+        |> Plug.Conn.put_req_header("x-datadog-origin", "rum")
+
+      assert {:ok, %SpanContext{} = span_context} = Adapter.distributed_context(conn, [])
+      assert span_context.trace_id == 123
+      assert :proplists.get_value("_dd.origin", span_context.baggage) == "rum"
+    end
+
+    test "priority defaults to nil if there is no x-datadog-sampling-priority header" do
       conn =
         :get
         |> Plug.Test.conn("/")
         |> Plug.Conn.put_req_header("x-datadog-trace-id", "123")
         |> Plug.Conn.put_req_header("x-datadog-parent-id", "456")
 
-      assert {:ok, %SpanContext{priority: 1}} = Adapter.distributed_context(conn, [])
+      assert {:ok, %SpanContext{priority: nil}} = Adapter.distributed_context(conn, [])
     end
 
     test "returns an error when it cannot detect both a Trace ID and a Span ID" do
@@ -127,13 +139,13 @@ defmodule SpandexDatadog.Test.AdapterTest do
       assert span_context.priority == 2
     end
 
-    test "priority defaults to 1 (i.e. we currently assume all distributed traces should be kept)" do
+    test "priority is nil if x-datadog-sampling-priority header is not present" do
       headers = %{
         "x-datadog-trace-id" => "123",
         "x-datadog-parent-id" => "456"
       }
 
-      assert {:ok, %SpanContext{priority: 1}} = Adapter.distributed_context(headers, [])
+      assert {:ok, %SpanContext{priority: nil}} = Adapter.distributed_context(headers, [])
     end
 
     test "returns an error when it cannot detect both a Trace ID and a Span ID" do
@@ -151,8 +163,8 @@ defmodule SpandexDatadog.Test.AdapterTest do
 
       assert result == [
                {"x-datadog-trace-id", "123"},
-               {"x-datadog-parent-id", "456"},
                {"x-datadog-sampling-priority", "10"},
+               {"x-datadog-parent-id", "456"},
                {"header1", "value1"},
                {"header2", "value2"}
              ]
@@ -172,5 +184,18 @@ defmodule SpandexDatadog.Test.AdapterTest do
                "header2" => "value2"
              }
     end
+
+    test "Sets x-datadog-origin from baggage" do
+      span_context = %SpanContext{trace_id: 123, parent_id: 456, priority: 10, baggage: [{"_dd.origin", "rum"}]}
+
+      result = Adapter.inject_context(%{}, span_context, [])
+
+      assert result == %{
+               "x-datadog-trace-id" => "123",
+               "x-datadog-parent-id" => "456",
+               "x-datadog-sampling-priority" => "10",
+               "x-datadog-origin" => "rum"
+             }
+    end
   end
 end

From 322aa33d9a579a30fa05741f23896b091a40b509 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 14:27:22 -0500
Subject: [PATCH 02/44] Baggage keys are atoms

---
 lib/spandex_datadog/adapter.ex | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/lib/spandex_datadog/adapter.ex b/lib/spandex_datadog/adapter.ex
index 98a138f..1c6953f 100644
--- a/lib/spandex_datadog/adapter.ex
+++ b/lib/spandex_datadog/adapter.ex
@@ -82,7 +82,7 @@ defmodule SpandexDatadog.Adapter do
   end
 
   defp extract_header({"x-datadog-origin", value}, span_context) do
-    %{span_context | baggage: span_context.baggage ++ [{"_dd.origin", value}]}
+    %{span_context | baggage: span_context.baggage ++ [{:"_dd.origin", value}]}
   end
 
   # Update context with value if it is an integer
@@ -108,7 +108,7 @@ defmodule SpandexDatadog.Adapter do
   # to have onlly the trace_id and origin headers set, but not parent_id.
   # This might happen with RUM or synthetic traces.
   defp validate_context(%{parent_id: nil} = span_context) do
-    case :proplists.get_value("_dd.origin", span_context.baggage) do
+    case :proplists.get_value(:"_dd.origin", span_context.baggage) do
       :undefined ->
         {:error, :no_distributed_trace}
 
@@ -128,12 +128,11 @@ defmodule SpandexDatadog.Adapter do
   end
 
   defp inject_header({:baggage, baggage}, headers) do
-    case :proplists.get_value("_dd.origin", baggage) do
-      :undefined ->
-        headers
-
-      value ->
+    case Keyword.fetch(baggage, :"_dd.origin") do
+      {:ok, value} ->
         [{"x-datadog-origin", value} | headers]
+      :error ->
+        headers
     end
   end
 

From fbbebcd043bdb01d4e47026ad11bd28fd3670ac5 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 14:28:51 -0500
Subject: [PATCH 03/44] Baggage keys are atoms.

---
 test/adapter_test.exs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/adapter_test.exs b/test/adapter_test.exs
index 36d64fe..3837eef 100644
--- a/test/adapter_test.exs
+++ b/test/adapter_test.exs
@@ -97,7 +97,7 @@ defmodule SpandexDatadog.Test.AdapterTest do
 
       assert {:ok, %SpanContext{} = span_context} = Adapter.distributed_context(conn, [])
       assert span_context.trace_id == 123
-      assert :proplists.get_value("_dd.origin", span_context.baggage) == "rum"
+      assert span_context.baggage[:"_dd.origin"] == "rum"
     end
 
     test "priority defaults to nil if there is no x-datadog-sampling-priority header" do
@@ -186,7 +186,7 @@ defmodule SpandexDatadog.Test.AdapterTest do
     end
 
     test "Sets x-datadog-origin from baggage" do
-      span_context = %SpanContext{trace_id: 123, parent_id: 456, priority: 10, baggage: [{"_dd.origin", "rum"}]}
+      span_context = %SpanContext{trace_id: 123, parent_id: 456, priority: 10, baggage: [{:"_dd.origin", "rum"}]}
 
       result = Adapter.inject_context(%{}, span_context, [])
 

From b7cb9e8c005e4297501b24f0aa5472a5cb20710c Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 14:29:22 -0500
Subject: [PATCH 04/44] Format test names to start lowercase

---
 test/adapter_test.exs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/test/adapter_test.exs b/test/adapter_test.exs
index 3837eef..b14de1d 100644
--- a/test/adapter_test.exs
+++ b/test/adapter_test.exs
@@ -155,7 +155,7 @@ defmodule SpandexDatadog.Test.AdapterTest do
   end
 
   describe "inject_context/3" do
-    test "Prepends distributed tracing headers to an existing list of headers" do
+    test "prepends distributed tracing headers to an existing list of headers" do
       span_context = %SpanContext{trace_id: 123, parent_id: 456, priority: 10}
       headers = [{"header1", "value1"}, {"header2", "value2"}]
 
@@ -170,7 +170,7 @@ defmodule SpandexDatadog.Test.AdapterTest do
              ]
     end
 
-    test "Merges distributed tracing headers with an existing map of headers" do
+    test "merges distributed tracing headers with an existing map of headers" do
       span_context = %SpanContext{trace_id: 123, parent_id: 456, priority: 10}
       headers = %{"header1" => "value1", "header2" => "value2"}
 
@@ -185,7 +185,7 @@ defmodule SpandexDatadog.Test.AdapterTest do
              }
     end
 
-    test "Sets x-datadog-origin from baggage" do
+    test "sets x-datadog-origin from baggage" do
       span_context = %SpanContext{trace_id: 123, parent_id: 456, priority: 10, baggage: [{:"_dd.origin", "rum"}]}
 
       result = Adapter.inject_context(%{}, span_context, [])

From 63bec7402aaf233137affee2601f109e7ead9b1f Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 14:30:56 -0500
Subject: [PATCH 05/44] Set sampling via tags

---
 lib/spandex_datadog/api_server.ex | 150 ++++++++++++++++++++++--------
 test/api_server_test.exs          |  56 ++++++-----
 2 files changed, 143 insertions(+), 63 deletions(-)

diff --git a/lib/spandex_datadog/api_server.ex b/lib/spandex_datadog/api_server.ex
index 416698f..2ce8f19 100644
--- a/lib/spandex_datadog/api_server.ex
+++ b/lib/spandex_datadog/api_server.ex
@@ -161,8 +161,8 @@ defmodule SpandexDatadog.ApiServer do
   @spec format(Span.t()) :: map()
   def format(%Span{} = span), do: format(span, 1, [])
 
-  @spec format(Span.t(), integer(), Keyword.t()) :: map()
-  def format(%Span{} = span, priority, _baggage) do
+  @spec format(Span.t(), integer() | nil, Keyword.t()) :: map()
+  def format(%Span{} = span, priority, baggage) do
     %{
       trace_id: span.trace_id,
       span_id: span.id,
@@ -174,13 +174,8 @@ defmodule SpandexDatadog.ApiServer do
       resource: span.resource || span.name,
       service: span.service,
       type: span.type,
-      meta: meta(span),
-      metrics:
-        metrics(span, %{
-          _sampling_priority_v1: priority,
-          "_dd.rule_psr": 1.0,
-          "_dd.limit_psr": 1.0
-        })
+      meta: meta(span, priority, baggage),
+      metrics: metrics(span, priority, baggage)
     }
   end
 
@@ -243,18 +238,32 @@ defmodule SpandexDatadog.ApiServer do
     end)
   end
 
-  @spec meta(Span.t()) :: map
-  defp meta(span) do
+  @spec meta(Span.t(), integer() | nil, Keyword.t()) :: map()
+  defp meta(span, _priority, baggage) do
     %{}
+    |> add_baggage_meta(baggage)
     |> add_datadog_meta(span)
     |> add_error_data(span)
     |> add_http_data(span)
     |> add_sql_data(span)
-    |> add_tags(span)
+    |> add_tags_meta(span)
     |> Enum.reject(fn {_k, v} -> is_nil(v) end)
     |> Enum.into(%{})
   end
 
+  @spec add_baggage_meta(map(), Keyword.t()) :: map()
+  defp add_baggage_meta(meta, []), do: meta
+
+  defp add_baggage_meta(meta, baggage) do
+    # distributed tracing
+    case Keyword.fetch(baggage, :"_dd.origin") do
+      {:ok, value} ->
+        Map.put(meta, "_dd.origin", value)
+      :error ->
+        meta
+    end
+  end
+
   @spec add_datadog_meta(map, Span.t()) :: map
   defp add_datadog_meta(meta, %Span{env: nil}), do: meta
 
@@ -313,44 +322,107 @@ defmodule SpandexDatadog.ApiServer do
     |> Map.put("sql.db", sql[:db])
   end
 
-  @spec add_tags(map, Span.t()) :: map
-  defp add_tags(meta, %{tags: nil}), do: meta
+  @spec add_tags_meta(map(), Span.t()) :: map()
+  defp add_tags_meta(meta, %{tags: nil}), do: meta
+
+  defp add_tags_meta(meta, %{tags: tags}) do
+    Enum.reduce(tags, meta, &add_tag_meta/2)
+  end
 
-  defp add_tags(meta, %{tags: tags}) do
-    tags = tags |> Keyword.delete(:analytics_event)
+  defp add_tag_meta({:hostname, value}, meta) do
+    Map.put(meta, "_dd.hostname", value)
+  end
 
-    Map.merge(
-      meta,
-      tags
-      |> Enum.map(fn {k, v} -> {k, term_to_string(v)} end)
-      |> Enum.into(%{})
-    )
+  defp add_tag_meta({:origin, value}, meta) do
+    Map.put(meta, "_dd.origin", value)
   end
 
-  @spec metrics(Span.t(), map) :: map
-  defp metrics(span, initial_value = %{}) do
-    initial_value
-    |> add_metrics(span)
+  # Handled in metrics
+  defp add_tag_meta({:analytics_event, _value}, meta), do: meta
+
+  # Tags with numeric values go in metrics
+  defp add_tag_meta({_key, value}, meta) when is_integer(value) or is_float(value) do
+    meta
+  end
+
+  defp add_tag_meta({key, value}, meta) do
+    Map.put(meta, to_string(key), term_to_string(value))
+  end
+
+  # Some tags understood by Datadog:
+  # runtime-id
+  # language: "elixir"
+  # system.pid: OS pid
+  # peer.hostname: Hostname of external service interacted with
+  # peer.service: Name of external service that performed the work
+
+  @spec metrics(Span.t(), integer() | nil, Keyword.t()) :: map()
+  defp metrics(span, priority, _baggage) do
+    %{}
+    |> add_priority_metrics(priority)
+    |> add_tags_metrics(span)
     |> Enum.reject(fn {_k, v} -> is_nil(v) end)
     |> Enum.into(%{})
   end
 
-  @spec add_metrics(map, Span.t()) :: map
-  defp add_metrics(metrics, %{tags: nil}), do: metrics
+  # Special tag names come mostly from the Ruby Datadog library
+  # ddtrace-1.1.0/lib/ddtrace/transport/trace_formatter.rb
 
-  defp add_metrics(metrics, %{tags: tags}) do
-    with analytics_event <- tags |> Keyword.get(:analytics_event),
-         true <- analytics_event != nil do
-      Map.merge(
-        metrics,
-        %{"_dd1.sr.eausr" => 1}
-      )
-    else
-      _ ->
-        metrics
-    end
+  @spec add_tags_metrics(map(), Span.t()) :: map()
+  defp add_tags_metrics(meta, %{tags: nil}), do: meta
+
+  defp add_tags_metrics(meta, %{tags: tags}) do
+    Enum.reduce(tags, meta, &add_tag_metric/2)
   end
 
+  # Sampling
+  defp add_tag_metric({:agent_sample_rate, value}, metrics) do
+    Map.put(metrics, "_dd.agent_psr", value)
+  end
+
+  defp add_tag_metric({:sample_rate, value}, metrics) do
+    Map.put(metrics, "_dd1.sr.eausr", value)
+  end
+
+  # Backwards compatibility
+  defp add_tag_metric({:analytics_event, value}, metrics) when value in [nil, false], do: metrics
+
+  defp add_tag_metric({:analytics_event, _value}, metrics) do
+    Map.put(metrics, "_dd1.sr.eausr", 1)
+  end
+
+  # If rule sampling is applied to a span, set metric for the sample rate
+  # configured for that rule. This should be done regardless of sampling
+  # outcome.
+  defp add_tag_metric({:rule_sample_rate, value}, metrics) do
+    Map.put(metrics, "_dd.rule_psr", value)
+  end
+
+  # If rate limiting is checked on a span, set metric for the effective rate
+  # limiting rate applied. This should be done regardless of rate limiting
+  # outcome.
+  defp add_tag_metric({:rate_limiter_rate, value}, metrics) do
+    Map.put(metrics, "_dd.limit_psr", value)
+  end
+
+  defp add_tag_metric({key, value}, metrics) when is_integer(value) or is_float(value) do
+    Map.put(metrics, to_string(key), value)
+  end
+
+  defp add_tag_metric(_, metrics) do
+    metrics
+  end
+
+  # Set priority from context
+  @spec add_priority_metrics(map(), integer() | nil) :: map()
+  defp add_priority_metrics(metrics, nil), do: metrics
+
+  # Distributed tracing
+  defp add_priority_metrics(metrics, priority) do
+    Map.put(metrics, "_sampling_priority_v1", priority)
+  end
+
+
   @spec error(nil | Keyword.t()) :: integer
   defp error(nil), do: 0
 
diff --git a/test/api_server_test.exs b/test/api_server_test.exs
index 1ed7540..df54365 100644
--- a/test/api_server_test.exs
+++ b/test/api_server_test.exs
@@ -61,7 +61,8 @@ defmodule SpandexDatadog.ApiServerTest do
         service: :bar,
         env: "local",
         name: "bar",
-        trace_id: trace_id
+        trace_id: trace_id,
+        tags: [analytics_event: true]
       )
 
     {:ok, span_3} =
@@ -73,10 +74,17 @@ defmodule SpandexDatadog.ApiServerTest do
         env: "local",
         name: "bar",
         trace_id: trace_id,
-        tags: [analytics_event: true]
+        tags: [
+          hostname: "moon",
+          origin: "web",
+          agent_sample_rate: 1.0,
+          sample_rate: 1.0,
+          rule_sample_rate: 1.0,
+          rate_limiter_rate: 1.0,
+        ]
       )
 
-    trace = %Trace{spans: [span_1, span_2, span_3]}
+    trace = %Trace{spans: [span_1, span_2, span_3], priority: 2}
 
     {
       :ok,
@@ -170,7 +178,6 @@ defmodule SpandexDatadog.ApiServerTest do
           "duration" => 100_000,
           "error" => 0,
           "meta" => %{
-            "bar" => "321",
             "baz" => "{1, 2}",
             "buz" => "blitz",
             "env" => "local",
@@ -178,9 +185,8 @@ defmodule SpandexDatadog.ApiServerTest do
             "zyx" => "[xyz: {1, 2}]"
           },
           "metrics" => %{
-            "_sampling_priority_v1" => 1,
-            "_dd.rule_psr" => 1.0,
-            "_dd.limit_psr" => 1.0
+            "bar" => 321,
+            "_sampling_priority_v1" => 2
           },
           "name" => "foo",
           "resource" => "foo",
@@ -196,9 +202,8 @@ defmodule SpandexDatadog.ApiServerTest do
             "env" => "local"
           },
           "metrics" => %{
-            "_sampling_priority_v1" => 1,
-            "_dd.rule_psr" => 1.0,
-            "_dd.limit_psr" => 1.0
+            "_dd1.sr.eausr" => 1,
+            "_sampling_priority_v1" => 2
           },
           "name" => "bar",
           "resource" => "bar",
@@ -211,13 +216,16 @@ defmodule SpandexDatadog.ApiServerTest do
           "duration" => 100_000_000,
           "error" => 0,
           "meta" => %{
-            "env" => "local"
+            "env" => "local",
+            "_dd.hostname" => "moon",
+            "_dd.origin" => "web"
           },
           "metrics" => %{
-            "_dd1.sr.eausr" => 1,
-            "_sampling_priority_v1" => 1,
+            "_dd.agent_psr" => 1.0,
+            "_dd1.sr.eausr" => 1.0,
             "_dd.rule_psr" => 1.0,
-            "_dd.limit_psr" => 1.0
+            "_dd.limit_psr" => 1.0,
+            "_sampling_priority_v1" => 2
           },
           "name" => "bar",
           "resource" => "bar",
@@ -260,7 +268,6 @@ defmodule SpandexDatadog.ApiServerTest do
           "duration" => 100_000,
           "error" => 0,
           "meta" => %{
-            "bar" => "321",
             "baz" => "{1, 2}",
             "buz" => "blitz",
             "env" => "local",
@@ -268,9 +275,8 @@ defmodule SpandexDatadog.ApiServerTest do
             "zyx" => "[xyz: {1, 2}]"
           },
           "metrics" => %{
-            "_sampling_priority_v1" => 1,
-            "_dd.rule_psr" => 1.0,
-            "_dd.limit_psr" => 1.0
+            "bar" => 321,
+            "_sampling_priority_v1" => 2
           },
           "name" => "foo",
           "resource" => "foo",
@@ -286,9 +292,8 @@ defmodule SpandexDatadog.ApiServerTest do
             "env" => "local"
           },
           "metrics" => %{
-            "_sampling_priority_v1" => 1,
-            "_dd.rule_psr" => 1.0,
-            "_dd.limit_psr" => 1.0
+            "_dd1.sr.eausr" => 1,
+            "_sampling_priority_v1" => 2
           },
           "name" => "bar",
           "resource" => "bar",
@@ -301,13 +306,16 @@ defmodule SpandexDatadog.ApiServerTest do
           "duration" => 100_000_000,
           "error" => 0,
           "meta" => %{
-            "env" => "local"
+            "env" => "local",
+            "_dd.hostname" => "moon",
+            "_dd.origin" => "web"
           },
           "metrics" => %{
+            "_dd.agent_psr" => 1.0,
             "_dd.rule_psr" => 1.0,
             "_dd.limit_psr" => 1.0,
-            "_dd1.sr.eausr" => 1,
-            "_sampling_priority_v1" => 1
+            "_dd1.sr.eausr" => 1.0,
+            "_sampling_priority_v1" => 2
           },
           "name" => "bar",
           "resource" => "bar",

From 7294fa0558019587a76059976974b6f1b85c0ddc Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 14:45:54 -0500
Subject: [PATCH 06/44] Use Config instead of Mix.Config

---
 config/config.exs | 13 ++++++++++---
 config/dev.exs    |  2 +-
 config/test.exs   |  2 +-
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/config/config.exs b/config/config.exs
index 0218721..40bbb8f 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -1,5 +1,12 @@
 # This file is responsible for configuring your application
-# and its dependencies with the aid of the Mix.Config module.
-use Mix.Config
+# and its dependencies with the aid of the Config module.
+#
+# This configuration file is loaded before any dependency and
+# is restricted to this project.
 
-import_config "./#{Mix.env()}.exs"
+# General application configuration
+import Config
+
+# Import environment specific config. This must remain at the bottom
+# of this file so it overrides the configuration defined above.
+import_config "#{config_env()}.exs"
diff --git a/config/dev.exs b/config/dev.exs
index 45c2b77..3ea6615 100644
--- a/config/dev.exs
+++ b/config/dev.exs
@@ -1,4 +1,4 @@
-use Mix.Config
+import Config
 
 config :git_ops,
   mix_project: SpandexDatadog.MixProject,
diff --git a/config/test.exs b/config/test.exs
index 0a68357..526e7bd 100644
--- a/config/test.exs
+++ b/config/test.exs
@@ -1,4 +1,4 @@
-use Mix.Config
+import Config
 
 config :logger, :console,
   level: :debug,

From 6c98e16f76f60d2c73ca6c26c4a898768b101f69 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 14:57:30 -0500
Subject: [PATCH 07/44] Remove parens on functions without parameters

---
 lib/spandex_datadog/adapter.ex    | 8 ++++----
 lib/spandex_datadog/api_server.ex | 3 +--
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/lib/spandex_datadog/adapter.ex b/lib/spandex_datadog/adapter.ex
index 1c6953f..42560e0 100644
--- a/lib/spandex_datadog/adapter.ex
+++ b/lib/spandex_datadog/adapter.ex
@@ -15,17 +15,17 @@ defmodule SpandexDatadog.Adapter do
   @max_id 9_223_372_036_854_775_807
 
   @impl Spandex.Adapter
-  def trace_id(), do: :rand.uniform(@max_id)
+  def trace_id, do: :rand.uniform(@max_id)
 
   @impl Spandex.Adapter
-  def span_id(), do: trace_id()
+  def span_id, do: trace_id()
 
   @impl Spandex.Adapter
-  def now(), do: :os.system_time(:nano_seconds)
+  def now, do: :os.system_time(:nano_seconds)
 
   @impl Spandex.Adapter
   @spec default_sender() :: SpandexDatadog.ApiServer
-  def default_sender() do
+  def default_sender do
     SpandexDatadog.ApiServer
   end
 
diff --git a/lib/spandex_datadog/api_server.ex b/lib/spandex_datadog/api_server.ex
index 2ce8f19..a4fbe0d 100644
--- a/lib/spandex_datadog/api_server.ex
+++ b/lib/spandex_datadog/api_server.ex
@@ -91,7 +91,7 @@ defmodule SpandexDatadog.ApiServer do
   @cgroup_task "[0-9a-f]{32}-\\d+"
   @cgroup_regex Regex.compile!(".*(#{@cgroup_uuid}|#{@cgroup_ctnr}|#{@cgroup_task})(?:\\.scope)?$", "m")
 
-  defp get_container_id() do
+  defp get_container_id do
     with {:ok, file_binary} <- File.read("/proc/self/cgroup"),
          [_, container_id] <- Regex.run(@cgroup_regex, file_binary) do
       container_id
@@ -422,7 +422,6 @@ defmodule SpandexDatadog.ApiServer do
     Map.put(metrics, "_sampling_priority_v1", priority)
   end
 
-
   @spec error(nil | Keyword.t()) :: integer
   defp error(nil), do: 0
 

From 13f92f46a6234a41075b710d804f3c9ec98d6a91 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 14:57:43 -0500
Subject: [PATCH 08/44] Remove parens on functions without parameters

---
 test/support/traced_module.ex | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/test/support/traced_module.ex b/test/support/traced_module.ex
index e4f2fec..185907b 100644
--- a/test/support/traced_module.ex
+++ b/test/support/traced_module.ex
@@ -11,31 +11,31 @@ defmodule SpandexDatadog.Test.TracedModule do
 
   # Traces
 
-  def trace_one_thing() do
+  def trace_one_thing do
     Tracer.trace "trace_one_thing/0" do
       do_one_thing()
     end
   end
 
-  def trace_with_special_name() do
+  def trace_with_special_name do
     Tracer.trace "special_name", service: :special_service do
       do_one_special_name_thing()
     end
   end
 
-  def trace_one_error() do
+  def trace_one_error do
     Tracer.trace "trace_one_error/0" do
       raise TestError, message: "trace_one_error"
     end
   end
 
-  def error_two_deep() do
+  def error_two_deep do
     Tracer.trace "error_two_deep/0" do
       error_one_deep()
     end
   end
 
-  def two_fail_one_succeeds() do
+  def two_fail_one_succeeds do
     Tracer.trace "two_fail_one_succeeds/0" do
       try do
         _ = error_one_deep()
@@ -50,25 +50,25 @@ defmodule SpandexDatadog.Test.TracedModule do
 
   # Spans
 
-  def error_one_deep() do
+  def error_one_deep do
     Tracer.span "error_one_deep/0" do
       raise TestError, message: "error_one_deep"
     end
   end
 
-  def manually_span_one_thing() do
+  def manually_span_one_thing do
     Tracer.span "manually_span_one_thing/0" do
       :timer.sleep(100)
     end
   end
 
-  def do_one_thing() do
+  def do_one_thing do
     Tracer.span "do_one_thing/0" do
       :timer.sleep(100)
     end
   end
 
-  def do_one_special_name_thing() do
+  def do_one_special_name_thing do
     Tracer.span "special_name_span", service: :special_span_service do
       :timer.sleep(100)
     end

From b21745c5fa75aabb104d23aae098ee82d65c870c Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 15:16:30 -0500
Subject: [PATCH 09/44] Add credo and dialyzer.

---
 mix.exs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mix.exs b/mix.exs
index ad3ce39..2a5e38c 100644
--- a/mix.exs
+++ b/mix.exs
@@ -55,6 +55,8 @@ defmodule SpandexDatadog.MixProject do
       {:spandex, "~> 3.0"},
       {:telemetry, "~> 0.4.2 or ~> 1.0"},
       # Dev- and test-only deps
+      {:credo, "~> 1.6", only: [:dev, :test], runtime: false},
+      {:dialyxir, "~> 1.0", only: [:dev, :test], runtime: false},
       {:ex_doc, ">= 0.0.0", only: :dev, runtime: false},
       {:httpoison, "~> 0.13 or ~> 1.0", only: :test}
     ]

From ea15a735fbc3babec632b0098a326fd75289ad2f Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 15:17:12 -0500
Subject: [PATCH 10/44] Specify spandex from github

---
 mix.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mix.exs b/mix.exs
index 2a5e38c..34819b1 100644
--- a/mix.exs
+++ b/mix.exs
@@ -52,7 +52,7 @@ defmodule SpandexDatadog.MixProject do
   defp deps do
     [
       {:msgpax, "~> 2.2.1 or ~> 2.3"},
-      {:spandex, "~> 3.0"},
+      {:spandex, github: "TheRealReal/spandex", branch: "distributed-sampling-priority"},
       {:telemetry, "~> 0.4.2 or ~> 1.0"},
       # Dev- and test-only deps
       {:credo, "~> 1.6", only: [:dev, :test], runtime: false},

From 97ebb97fe033607c2780634eb4bc21c0a0c737bd Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 15:17:26 -0500
Subject: [PATCH 11/44] Upgrade libraries

---
 mix.lock | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/mix.lock b/mix.lock
index 247ca86..7cdee47 100644
--- a/mix.lock
+++ b/mix.lock
@@ -1,24 +1,30 @@
 %{
-  "certifi": {:hex, :certifi, "2.6.1", "dbab8e5e155a0763eea978c913ca280a6b544bfa115633fa20249c3d396d9493", [:rebar3], [], "hexpm", "524c97b4991b3849dd5c17a631223896272c6b0af446778ba4675a1dff53bb7e"},
-  "earmark_parser": {:hex, :earmark_parser, "1.4.15", "b29e8e729f4aa4a00436580dcc2c9c5c51890613457c193cc8525c388ccb2f06", [:mix], [], "hexpm", "044523d6438ea19c1b8ec877ec221b008661d3c27e3b848f4c879f500421ca5c"},
-  "ex_doc": {:hex, :ex_doc, "0.25.3", "3edf6a0d70a39d2eafde030b8895501b1c93692effcbd21347296c18e47618ce", [:mix], [{:earmark_parser, "~> 1.4.0", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1", [hex: :makeup_erlang, repo: "hexpm", optional: false]}], "hexpm", "9ebebc2169ec732a38e9e779fd0418c9189b3ca93f4a676c961be6c1527913f5"},
-  "hackney": {:hex, :hackney, "1.17.4", "99da4674592504d3fb0cfef0db84c3ba02b4508bae2dff8c0108baa0d6e0977c", [:rebar3], [{:certifi, "~>2.6.1", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "~>6.1.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "~>1.0.0", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~>1.1", [hex: :mimerl, repo: "hexpm", optional: false]}, {:parse_trans, "3.3.1", [hex: :parse_trans, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "~>1.1.0", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}, {:unicode_util_compat, "~>0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "de16ff4996556c8548d512f4dbe22dd58a587bf3332e7fd362430a7ef3986b16"},
-  "httpoison": {:hex, :httpoison, "1.8.0", "6b85dea15820b7804ef607ff78406ab449dd78bed923a49c7160e1886e987a3d", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "28089eaa98cf90c66265b6b5ad87c59a3729bea2e74e9d08f9b51eb9729b3c3a"},
+  "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], [], "hexpm", "7af5c7e09fe1d40f76c8e4f9dd2be7cebd83909f31fee7cd0e9eadc567da8353"},
+  "certifi": {:hex, :certifi, "2.9.0", "6f2a475689dd47f19fb74334859d460a2dc4e3252a3324bd2111b8f0429e7e21", [:rebar3], [], "hexpm", "266da46bdb06d6c6d35fde799bcb28d36d985d424ad7c08b5bb48f5b5cdd4641"},
+  "credo": {:hex, :credo, "1.6.6", "f51f8d45db1af3b2e2f7bee3e6d3c871737bda4a91bff00c5eec276517d1a19c", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, repo: "hexpm", optional: false]}, {:file_system, "~> 0.2.8", [hex: :file_system, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: false]}], "hexpm", "625520ce0984ee0f9f1f198165cd46fa73c1e59a17ebc520038b8fce056a5bdc"},
+  "dialyxir": {:hex, :dialyxir, "1.2.0", "58344b3e87c2e7095304c81a9ae65cb68b613e28340690dfe1a5597fd08dec37", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "61072136427a851674cab81762be4dbeae7679f85b1272b6d25c3a839aff8463"},
+  "earmark_parser": {:hex, :earmark_parser, "1.4.26", "f4291134583f373c7d8755566122908eb9662df4c4b63caa66a0eabe06569b0a", [:mix], [], "hexpm", "48d460899f8a0c52c5470676611c01f64f3337bad0b26ddab43648428d94aabc"},
+  "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
+  "ex_doc": {:hex, :ex_doc, "0.28.4", "001a0ea6beac2f810f1abc3dbf4b123e9593eaa5f00dd13ded024eae7c523298", [:mix], [{:earmark_parser, "~> 1.4.19", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}, {:makeup_erlang, "~> 0.1", [hex: :makeup_erlang, repo: "hexpm", optional: false]}], "hexpm", "bf85d003dd34911d89c8ddb8bda1a958af3471a274a4c2150a9c01c78ac3f8ed"},
+  "file_system": {:hex, :file_system, "0.2.10", "fb082005a9cd1711c05b5248710f8826b02d7d1784e7c3451f9c1231d4fc162d", [:mix], [], "hexpm", "41195edbfb562a593726eda3b3e8b103a309b733ad25f3d642ba49696bf715dc"},
+  "hackney": {:hex, :hackney, "1.18.1", "f48bf88f521f2a229fc7bae88cf4f85adc9cd9bcf23b5dc8eb6a1788c662c4f6", [:rebar3], [{:certifi, "~>2.9.0", [hex: :certifi, repo: "hexpm", optional: false]}, {:idna, "~>6.1.0", [hex: :idna, repo: "hexpm", optional: false]}, {:metrics, "~>1.0.0", [hex: :metrics, repo: "hexpm", optional: false]}, {:mimerl, "~>1.1", [hex: :mimerl, repo: "hexpm", optional: false]}, {:parse_trans, "3.3.1", [hex: :parse_trans, repo: "hexpm", optional: false]}, {:ssl_verify_fun, "~>1.1.0", [hex: :ssl_verify_fun, repo: "hexpm", optional: false]}, {:unicode_util_compat, "~>0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "a4ecdaff44297e9b5894ae499e9a070ea1888c84afdd1fd9b7b2bc384950128e"},
+  "httpoison": {:hex, :httpoison, "1.8.2", "9eb9c63ae289296a544842ef816a85d881d4a31f518a0fec089aaa744beae290", [:mix], [{:hackney, "~> 1.17", [hex: :hackney, repo: "hexpm", optional: false]}], "hexpm", "2bb350d26972e30c96e2ca74a1aaf8293d61d0742ff17f01e0279fef11599921"},
   "idna": {:hex, :idna, "6.1.1", "8a63070e9f7d0c62eb9d9fcb360a7de382448200fbbd1b106cc96d3d8099df8d", [:rebar3], [{:unicode_util_compat, "~>0.7.0", [hex: :unicode_util_compat, repo: "hexpm", optional: false]}], "hexpm", "92376eb7894412ed19ac475e4a86f7b413c1b9fbb5bd16dccd57934157944cea"},
-  "makeup": {:hex, :makeup, "1.0.5", "d5a830bc42c9800ce07dd97fa94669dfb93d3bf5fcf6ea7a0c67b2e0e4a7f26c", [:mix], [{:nimble_parsec, "~> 0.5 or ~> 1.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "cfa158c02d3f5c0c665d0af11512fed3fba0144cf1aadee0f2ce17747fba2ca9"},
-  "makeup_elixir": {:hex, :makeup_elixir, "0.15.1", "b5888c880d17d1cc3e598f05cdb5b5a91b7b17ac4eaf5f297cb697663a1094dd", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.1", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "db68c173234b07ab2a07f645a5acdc117b9f99d69ebf521821d89690ae6c6ec8"},
+  "jason": {:hex, :jason, "1.3.0", "fa6b82a934feb176263ad2df0dbd91bf633d4a46ebfdffea0c8ae82953714946", [:mix], [{:decimal, "~> 1.0 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm", "53fc1f51255390e0ec7e50f9cb41e751c260d065dcba2bf0d08dc51a4002c2ac"},
+  "makeup": {:hex, :makeup, "1.1.0", "6b67c8bc2882a6b6a445859952a602afc1a41c2e08379ca057c0f525366fc3ca", [:mix], [{:nimble_parsec, "~> 1.2.2 or ~> 1.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "0a45ed501f4a8897f580eabf99a2e5234ea3e75a4373c8a52824f6e873be57a6"},
+  "makeup_elixir": {:hex, :makeup_elixir, "0.16.0", "f8c570a0d33f8039513fbccaf7108c5d750f47d8defd44088371191b76492b0b", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.2.3", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "28b2cbdc13960a46ae9a8858c4bebdec3c9a6d7b4b9e7f4ed1502f8159f338e7"},
   "makeup_erlang": {:hex, :makeup_erlang, "0.1.1", "3fcb7f09eb9d98dc4d208f49cc955a34218fc41ff6b84df7c75b3e6e533cc65f", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}], "hexpm", "174d0809e98a4ef0b3309256cbf97101c6ec01c4ab0b23e926a9e17df2077cbb"},
   "metrics": {:hex, :metrics, "1.0.1", "25f094dea2cda98213cecc3aeff09e940299d950904393b2a29d191c346a8486", [:rebar3], [], "hexpm", "69b09adddc4f74a40716ae54d140f93beb0fb8978d8636eaded0c31b6f099f16"},
-  "mime": {:hex, :mime, "2.0.1", "0de4c81303fe07806ebc2494d5321ce8fb4df106e34dd5f9d787b637ebadc256", [:mix], [], "hexpm", "7a86b920d2aedce5fb6280ac8261ac1a739ae6c1a1ad38f5eadf910063008942"},
+  "mime": {:hex, :mime, "2.0.3", "3676436d3d1f7b81b5a2d2bd8405f412c677558c81b1c92be58c00562bb59095", [:mix], [], "hexpm", "27a30bf0db44d25eecba73755acf4068cbfe26a4372f9eb3e4ea3a45956bff6b"},
   "mimerl": {:hex, :mimerl, "1.2.0", "67e2d3f571088d5cfd3e550c383094b47159f3eee8ffa08e64106cdf5e981be3", [:rebar3], [], "hexpm", "f278585650aa581986264638ebf698f8bb19df297f66ad91b18910dfc6e19323"},
   "msgpax": {:hex, :msgpax, "2.3.0", "14f52ad249a3f77b5e2d59f6143e6c18a6e74f34666989e22bac0a465f9835cc", [:mix], [{:plug, "~> 1.0", [hex: :plug, repo: "hexpm", optional: true]}], "hexpm", "65c36846a62ed5615baf7d7d47babb6541313a6c0b6d2ff19354bd518f52df7e"},
-  "nimble_parsec": {:hex, :nimble_parsec, "1.1.0", "3a6fca1550363552e54c216debb6a9e95bd8d32348938e13de5eda962c0d7f89", [:mix], [], "hexpm", "08eb32d66b706e913ff748f11694b17981c0b04a33ef470e33e11b3d3ac8f54b"},
+  "nimble_parsec": {:hex, :nimble_parsec, "1.2.3", "244836e6e3f1200c7f30cb56733fd808744eca61fd182f731eac4af635cc6d0b", [:mix], [], "hexpm", "c8d789e39b9131acf7b99291e93dae60ab48ef14a7ee9d58c6964f59efb570b0"},
   "optimal": {:hex, :optimal, "0.3.6", "46bbf52fbbbd238cda81e02560caa84f93a53c75620f1fe19e81e4ae7b07d1dd", [:mix], [], "hexpm", "1a06ea6a653120226b35b283a1cd10039550f2c566edcdec22b29316d73640fd"},
   "parse_trans": {:hex, :parse_trans, "3.3.1", "16328ab840cc09919bd10dab29e431da3af9e9e7e7e6f0089dd5a2d2820011d8", [:rebar3], [], "hexpm", "07cd9577885f56362d414e8c4c4e6bdf10d43a8767abb92d24cbe8b24c54888b"},
-  "plug": {:hex, :plug, "1.12.1", "645678c800601d8d9f27ad1aebba1fdb9ce5b2623ddb961a074da0b96c35187d", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.3 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "d57e799a777bc20494b784966dc5fbda91eb4a09f571f76545b72a634ce0d30b"},
+  "plug": {:hex, :plug, "1.13.6", "187beb6b67c6cec50503e940f0434ea4692b19384d47e5fdfd701e93cadb4cc2", [:mix], [{:mime, "~> 1.0 or ~> 2.0", [hex: :mime, repo: "hexpm", optional: false]}, {:plug_crypto, "~> 1.1.1 or ~> 1.2", [hex: :plug_crypto, repo: "hexpm", optional: false]}, {:telemetry, "~> 0.4.3 or ~> 1.0", [hex: :telemetry, repo: "hexpm", optional: false]}], "hexpm", "02b9c6b9955bce92c829f31d6284bf53c591ca63c4fb9ff81dfd0418667a34ff"},
   "plug_crypto": {:hex, :plug_crypto, "1.2.2", "05654514ac717ff3a1843204b424477d9e60c143406aa94daf2274fdd280794d", [:mix], [], "hexpm", "87631c7ad914a5a445f0a3809f99b079113ae4ed4b867348dd9eec288cecb6db"},
-  "spandex": {:hex, :spandex, "3.0.3", "91aa318f3de696bb4d931adf65f7ebdbe5df25cccce1fe8fd376a44c46bcf69b", [: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", "e3e6c319d0ab478ddc9a39102a727a410c962b4d51c0932c72279b86d3b17044"},
+  "spandex": {:git, "https://github.com/TheRealReal/spandex.git", "6ae8458e5c558ee5b5972eb89a800c4cf9ec1c17", [branch: "distributed-sampling-priority"]},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.6", "cf344f5692c82d2cd7554f5ec8fd961548d4fd09e7d22f5b62482e5aeaebd4b0", [:make, :mix, :rebar3], [], "hexpm", "bdb0d2471f453c88ff3908e7686f86f9be327d065cc1ec16fa4540197ea04680"},
-  "telemetry": {:hex, :telemetry, "1.0.0", "0f453a102cdf13d506b7c0ab158324c337c41f1cc7548f0bc0e130bbf0ae9452", [:rebar3], [], "hexpm", "73bc09fa59b4a0284efb4624335583c528e07ec9ae76aca96ea0673850aec57a"},
+  "telemetry": {:hex, :telemetry, "1.1.0", "a589817034a27eab11144ad24d5c0f9fab1f58173274b1e9bae7074af9cbee51", [:rebar3], [], "hexpm", "b727b2a1f75614774cff2d7565b64d0dfa5bd52ba517f16543e6fc7efcc0df48"},
   "unicode_util_compat": {:hex, :unicode_util_compat, "0.7.0", "bc84380c9ab48177092f43ac89e4dfa2c6d62b40b8bd132b1059ecc7232f9a78", [:rebar3], [], "hexpm", "25eee6d67df61960cf6a794239566599b09e17e668d3700247bc498638152521"},
 }

From a68debd26053477aa5ee377beef292eebaf839df Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 17:14:18 -0500
Subject: [PATCH 12/44] Ignore unrecognized headers

---
 lib/spandex_datadog/adapter.ex | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/spandex_datadog/adapter.ex b/lib/spandex_datadog/adapter.ex
index 42560e0..c0e6fc5 100644
--- a/lib/spandex_datadog/adapter.ex
+++ b/lib/spandex_datadog/adapter.ex
@@ -85,6 +85,10 @@ defmodule SpandexDatadog.Adapter do
     %{span_context | baggage: span_context.baggage ++ [{:"_dd.origin", value}]}
   end
 
+  defp extract_header(_, span_context) do
+    span_context
+  end
+
   # Update context with value if it is an integer
   @spec put_context_int(Spandex.SpanContext.t(), atom(), binary()) :: Spandex.SpanContext.t()
   defp put_context_int(span_context, key, value) do

From cbd8977c764bfb6ee6e55f26d852541feffd0960 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 18:32:13 -0500
Subject: [PATCH 13/44] Use Keyword module

---
 lib/spandex_datadog/adapter.ex | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/lib/spandex_datadog/adapter.ex b/lib/spandex_datadog/adapter.ex
index c0e6fc5..590f0c4 100644
--- a/lib/spandex_datadog/adapter.ex
+++ b/lib/spandex_datadog/adapter.ex
@@ -112,12 +112,10 @@ defmodule SpandexDatadog.Adapter do
   # to have onlly the trace_id and origin headers set, but not parent_id.
   # This might happen with RUM or synthetic traces.
   defp validate_context(%{parent_id: nil} = span_context) do
-    case :proplists.get_value(:"_dd.origin", span_context.baggage) do
-      :undefined ->
-        {:error, :no_distributed_trace}
-
-      _ ->
-        {:ok, span_context}
+    if Keyword.has_key?(span_context.baggage, :"_dd.origin") do
+      {:ok, span_context}
+    else
+      {:error, :no_distributed_trace}
     end
   end
 
@@ -135,6 +133,7 @@ defmodule SpandexDatadog.Adapter do
     case Keyword.fetch(baggage, :"_dd.origin") do
       {:ok, value} ->
         [{"x-datadog-origin", value} | headers]
+
       :error ->
         headers
     end

From 8f2075aa942ef374dfe2c31f11bbe822e391e3b7 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 18:32:28 -0500
Subject: [PATCH 14/44] mix format

---
 lib/spandex_datadog/api_server.ex | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/spandex_datadog/api_server.ex b/lib/spandex_datadog/api_server.ex
index a4fbe0d..4c24c3e 100644
--- a/lib/spandex_datadog/api_server.ex
+++ b/lib/spandex_datadog/api_server.ex
@@ -259,6 +259,7 @@ defmodule SpandexDatadog.ApiServer do
     case Keyword.fetch(baggage, :"_dd.origin") do
       {:ok, value} ->
         Map.put(meta, "_dd.origin", value)
+
       :error ->
         meta
     end

From b99404d85314258b4a76e70a546a08d45da6d8c9 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 9 Aug 2022 18:32:42 -0500
Subject: [PATCH 15/44] mix format

---
 test/api_server_test.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/api_server_test.exs b/test/api_server_test.exs
index df54365..b7b30eb 100644
--- a/test/api_server_test.exs
+++ b/test/api_server_test.exs
@@ -80,7 +80,7 @@ defmodule SpandexDatadog.ApiServerTest do
           agent_sample_rate: 1.0,
           sample_rate: 1.0,
           rule_sample_rate: 1.0,
-          rate_limiter_rate: 1.0,
+          rate_limiter_rate: 1.0
         ]
       )
 

From a73218aac85d20d8c9f0d92119d86f8ea5186d8d Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Wed, 10 Aug 2022 14:53:25 -0500
Subject: [PATCH 16/44] Add docs

---
 lib/spandex_datadog/api_server.ex | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/spandex_datadog/api_server.ex b/lib/spandex_datadog/api_server.ex
index 4c24c3e..2f73e7c 100644
--- a/lib/spandex_datadog/api_server.ex
+++ b/lib/spandex_datadog/api_server.ex
@@ -385,7 +385,8 @@ defmodule SpandexDatadog.ApiServer do
     Map.put(metrics, "_dd1.sr.eausr", value)
   end
 
-  # Backwards compatibility
+  # Set a segment to always be sampled.
+  # `sample_rate` tag should be used instead.
   defp add_tag_metric({:analytics_event, value}, metrics) when value in [nil, false], do: metrics
 
   defp add_tag_metric({:analytics_event, _value}, metrics) do

From 508ab18158a30b007c6cfaa24166edf3c47de596 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Thu, 11 Aug 2022 14:41:30 -0500
Subject: [PATCH 17/44] Use float value for analytics rate

---
 lib/spandex_datadog/api_server.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/spandex_datadog/api_server.ex b/lib/spandex_datadog/api_server.ex
index 2f73e7c..66ab10d 100644
--- a/lib/spandex_datadog/api_server.ex
+++ b/lib/spandex_datadog/api_server.ex
@@ -390,7 +390,7 @@ defmodule SpandexDatadog.ApiServer do
   defp add_tag_metric({:analytics_event, value}, metrics) when value in [nil, false], do: metrics
 
   defp add_tag_metric({:analytics_event, _value}, metrics) do
-    Map.put(metrics, "_dd1.sr.eausr", 1)
+    Map.put(metrics, "_dd1.sr.eausr", 1.0)
   end
 
   # If rule sampling is applied to a span, set metric for the sample rate

From 6fd352b1adc910d74a295d6ad7cf166a3a137da4 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Thu, 11 Aug 2022 14:42:21 -0500
Subject: [PATCH 18/44] Document max_id

---
 lib/spandex_datadog/adapter.ex | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/spandex_datadog/adapter.ex b/lib/spandex_datadog/adapter.ex
index 590f0c4..70499cb 100644
--- a/lib/spandex_datadog/adapter.ex
+++ b/lib/spandex_datadog/adapter.ex
@@ -12,7 +12,10 @@ defmodule SpandexDatadog.Adapter do
     Tracer
   }
 
+  # Max value for a trace_id. We only generate 63-bit integers due to
+  # limitations in other languages, but other systems may use the full 64-bits.
   @max_id 9_223_372_036_854_775_807
+  # @max_id Bitwise.bsl(1, 63) - 1
 
   @impl Spandex.Adapter
   def trace_id, do: :rand.uniform(@max_id)

From 2dcbc6968f296475bfda2a71589de46746b14b22 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Thu, 11 Aug 2022 14:44:24 -0500
Subject: [PATCH 19/44] Add functions to randomly sample traces

---
 lib/spandex_datadog/rate_sampler.ex | 39 +++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 lib/spandex_datadog/rate_sampler.ex

diff --git a/lib/spandex_datadog/rate_sampler.ex b/lib/spandex_datadog/rate_sampler.ex
new file mode 100644
index 0000000..05752a5
--- /dev/null
+++ b/lib/spandex_datadog/rate_sampler.ex
@@ -0,0 +1,39 @@
+defmodule SpandexDatadog.RateSampler do
+  @moduledoc """
+  Randomly sample a percentage of traces based on the trace_id.
+  """
+
+  # Max value for a trace_id that we generate.
+  @max_id Bitwise.bsl(1, 63) - 1
+
+  # We only generate 63-bit integers due to limitations in other languages, but
+  # support parsing 64-bit integers for distributed tracing since an upstream
+  # system may generate one.
+  @external_max_id Bitwise.bsl(1, 64)
+
+  @knuth_factor 1111111111111111111
+
+  @doc """
+  Determine whether a trace should be sampled.
+
+  This uses the `trace_id` and specified sample rate.
+  If the `trace_id` is a randomly generated integer, then it will
+  deterministically select a percentage of traces at random.
+
+  `sample_rate` is a float between 0.0 and 1.0. 0.0 means that no trace will
+  be sampled, and 1.0 means that all traces will be sampled.
+  """
+  @spec sampled?(non_neg_integer() | Spandex.Trace.t() | Spandex.Span.t(), float()) :: boolean()
+  def sampled?(trace_id, sample_rate) when is_integer(trace_id) do
+    threshold = sample_rate * @external_max_id
+    ((trace_id * @knuth_factor) % @external_max_id) <= threshold
+  end
+
+  def sampled?(%Spandex.Trace{trace_id: trace_id}, sample_rate) do
+    sampled?(trace_id, sample_rate)
+  end
+
+  def sampled?(%Spandex.Span{trace_id: trace_id}, sample_rate) do
+    sampled?(trace_id, sample_rate)
+  end
+end

From 680acc8dc3c80c1fa283a3e4e798c6fc035e2ed1 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Thu, 11 Aug 2022 14:51:09 -0500
Subject: [PATCH 20/44] Shortcut for common cases

---
 lib/spandex_datadog/rate_sampler.ex | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/spandex_datadog/rate_sampler.ex b/lib/spandex_datadog/rate_sampler.ex
index 05752a5..fe39d48 100644
--- a/lib/spandex_datadog/rate_sampler.ex
+++ b/lib/spandex_datadog/rate_sampler.ex
@@ -24,6 +24,10 @@ defmodule SpandexDatadog.RateSampler do
   be sampled, and 1.0 means that all traces will be sampled.
   """
   @spec sampled?(non_neg_integer() | Spandex.Trace.t() | Spandex.Span.t(), float()) :: boolean()
+  def sampled?(_, 1.0), do: true
+
+  def sampled?(_, 0.0), do: false
+
   def sampled?(trace_id, sample_rate) when is_integer(trace_id) do
     threshold = sample_rate * @external_max_id
     ((trace_id * @knuth_factor) % @external_max_id) <= threshold

From 31d0a9ea29e7ed52ec3dff6326d5bc7388792c32 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Thu, 11 Aug 2022 16:18:54 -0500
Subject: [PATCH 21/44] Use float

---
 test/api_server_test.exs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/api_server_test.exs b/test/api_server_test.exs
index b7b30eb..f61f3dd 100644
--- a/test/api_server_test.exs
+++ b/test/api_server_test.exs
@@ -202,7 +202,7 @@ defmodule SpandexDatadog.ApiServerTest do
             "env" => "local"
           },
           "metrics" => %{
-            "_dd1.sr.eausr" => 1,
+            "_dd1.sr.eausr" => 1.0,
             "_sampling_priority_v1" => 2
           },
           "name" => "bar",
@@ -292,7 +292,7 @@ defmodule SpandexDatadog.ApiServerTest do
             "env" => "local"
           },
           "metrics" => %{
-            "_dd1.sr.eausr" => 1,
+            "_dd1.sr.eausr" => 1.0,
             "_sampling_priority_v1" => 2
           },
           "name" => "bar",

From 27f9d9e7215f7975a7626e6d1b0a03075e927acb Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Thu, 11 Aug 2022 16:45:38 -0500
Subject: [PATCH 22/44] Finish rate sampler

---
 lib/spandex_datadog/rate_sampler.ex | 17 +++++++++--------
 test/rate_sampler_test.exs          | 25 +++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 8 deletions(-)
 create mode 100644 test/rate_sampler_test.exs

diff --git a/lib/spandex_datadog/rate_sampler.ex b/lib/spandex_datadog/rate_sampler.ex
index fe39d48..379ce21 100644
--- a/lib/spandex_datadog/rate_sampler.ex
+++ b/lib/spandex_datadog/rate_sampler.ex
@@ -1,11 +1,8 @@
 defmodule SpandexDatadog.RateSampler do
   @moduledoc """
-  Randomly sample a percentage of traces based on the trace_id.
+  Randomly sample a proportion of traces based on the trace_id.
   """
 
-  # Max value for a trace_id that we generate.
-  @max_id Bitwise.bsl(1, 63) - 1
-
   # We only generate 63-bit integers due to limitations in other languages, but
   # support parsing 64-bit integers for distributed tracing since an upstream
   # system may generate one.
@@ -23,17 +20,21 @@ defmodule SpandexDatadog.RateSampler do
   `sample_rate` is a float between 0.0 and 1.0. 0.0 means that no trace will
   be sampled, and 1.0 means that all traces will be sampled.
   """
-  @spec sampled?(non_neg_integer() | Spandex.Trace.t() | Spandex.Span.t(), float()) :: boolean()
+  @spec sampled?(non_neg_integer() | nil | Spandex.Trace.t() | Spandex.Span.t(), float()) :: boolean()
+  # trace_id may be nil when tracing is disabled
+  def sampled?(nil, 1.0), do: false
+
+  # Shortcut processing for common cases
   def sampled?(_, 1.0), do: true
 
   def sampled?(_, 0.0), do: false
 
   def sampled?(trace_id, sample_rate) when is_integer(trace_id) do
-    threshold = sample_rate * @external_max_id
-    ((trace_id * @knuth_factor) % @external_max_id) <= threshold
+    threshold = trunc(sample_rate * @external_max_id)
+    rem(trace_id * @knuth_factor, @external_max_id) <= threshold
   end
 
-  def sampled?(%Spandex.Trace{trace_id: trace_id}, sample_rate) do
+  def sampled?(%Spandex.Trace{id: trace_id}, sample_rate) do
     sampled?(trace_id, sample_rate)
   end
 
diff --git a/test/rate_sampler_test.exs b/test/rate_sampler_test.exs
new file mode 100644
index 0000000..4fe7aeb
--- /dev/null
+++ b/test/rate_sampler_test.exs
@@ -0,0 +1,25 @@
+defmodule SpandexDatadog.Test.RateSamplerTest do
+  use ExUnit.Case, async: true
+
+  alias SpandexDatadog.RateSampler
+
+  describe "sampled?/2" do
+    test "sample rate of 0.0 returns false" do
+      refute RateSampler.sampled?(1, 0.0)
+    end
+
+    test "sample rate of 1.0 returns true" do
+      assert RateSampler.sampled?(1, 1.0)
+    end
+
+    test "nil trace_id returns false" do
+      refute RateSampler.sampled?(nil, 1.0)
+    end
+
+    test "trace is sampled" do
+      trace_id = trunc(Bitwise.bsl(1, 64) / 2)
+      refute RateSampler.sampled?(trace_id, 0.25)
+      assert RateSampler.sampled?(trace_id, 0.75)
+    end
+  end
+end

From 132961cee70267f1bbe391f523a291cf3420e5ae Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Fri, 12 Aug 2022 10:24:26 -0500
Subject: [PATCH 23/44] Fix param

---
 lib/spandex_datadog/rate_sampler.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/spandex_datadog/rate_sampler.ex b/lib/spandex_datadog/rate_sampler.ex
index 379ce21..ed940a5 100644
--- a/lib/spandex_datadog/rate_sampler.ex
+++ b/lib/spandex_datadog/rate_sampler.ex
@@ -22,7 +22,7 @@ defmodule SpandexDatadog.RateSampler do
   """
   @spec sampled?(non_neg_integer() | nil | Spandex.Trace.t() | Spandex.Span.t(), float()) :: boolean()
   # trace_id may be nil when tracing is disabled
-  def sampled?(nil, 1.0), do: false
+  def sampled?(nil, _), do: false
 
   # Shortcut processing for common cases
   def sampled?(_, 1.0), do: true

From 26f3c03905c755822445d7689e3178021d193af3 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Fri, 19 Aug 2022 18:00:29 -0500
Subject: [PATCH 24/44] Update changelog

---
 CHANGELOG.md | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 45cc293..586e828 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,20 @@ See [Conventional Commits](Https://conventionalcommits.org) for commit guideline
 
 <!-- changelog -->
 
+### Breaking Changes:
+* Change default `priority` to `nil` (not set) instead of 1
+* Do not send metric for `priority` unless set
+* Do not set `x-datadog-sampling-priority` header unless priority is set
+* Use `sample_rate` tag to set `_dd1.sr.eausr` value
+* Use `rule_sample_rate` tag to set `_dd.rule_psr` without default (previously hard coded to 1.0)
+* Use `rate_limiter_rate` tag to set `_dd.limit_psr`, without default (previously hard coded to 1.0)
+* Update library deps
+
+### Features:
+* Handle `x-datadog-origin` header
+* Use `agent_sample_rate` tag to set `_dd.agent_psr`, without default (was 1.0)
+* Add sampler which samples a proportion of traces, setting `priority`
+
 ## [1.2.0](https://github.com/spandex-project/spandex_datadog/compare/1.1.0...1.2.0) (2021-10-23)
 
 ### Features:

From 2f7c7c362355d45bae44f5330e95395244ce08f3 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Mon, 22 Aug 2022 11:22:24 -0500
Subject: [PATCH 25/44] Update docs

---
 README.md | 111 +++++++++++++++++++++++++++++++++++++++++-------------
 1 file changed, 84 insertions(+), 27 deletions(-)

diff --git a/README.md b/README.md
index af2d977..a53a6d7 100644
--- a/README.md
+++ b/README.md
@@ -6,12 +6,11 @@
 [![License](https://img.shields.io/hexpm/l/spandex_datadog.svg)](https://github.com/spandex-project/spandex_datadog/blob/master/LICENSE)
 [![Last Updated](https://img.shields.io/github/last-commit/spandex-project/spandex_datadog.svg)](https://github.com/spandex-project/spandex_datadog/commits/master)
 
-A datadog adapter for the `:spandex` library.
+This is the Datadog adapter for the [Spandex](https://github.com/spandex-project/spandex) tracing library.
 
 ## Installation
 
-The package can be installed by adding `:spandex_datadog` to your list of
-dependencies in `mix.exs`:
+Add `:spandex_datadog` to the list of dependencies in `mix.exs`:
 
 ```elixir
 def deps do
@@ -21,14 +20,13 @@ def deps do
 end
 ```
 
-To start the datadog adapter, add a worker to your application's supervisor
+To start the Datadog adapter, add a worker to your application's supervisor.
 
 ```elixir
 # Example configuration
 
-# Note: You should put ApiServer before any other children in the list that
-# might try to send traces before the ApiServer has started up, for example
-# Ecto.Repo and Phoenix.Endpoint
+# Note: Put ApiServer before other children that might try to send traces
+# before ApiServer has started up, e.g. Ecto.Repo and Phoenix.Endpoint
 
 spandex_opts =
   [
@@ -53,15 +51,73 @@ Supvervisor.start_link(children, opts)
 
 ## Distributed Tracing
 
-Distributed tracing is supported via headers `x-datadog-trace-id`,
-`x-datadog-parent-id`, and `x-datadog-sampling-priority`. If they are set, the
-`Spandex.Plug.StartTrace` plug will act accordingly, continuing that trace and
-span instead of starting a new one.  *Both* `x-datadog-trace-id` and
-`x-datadog-parent-id` must be set for distributed tracing to work. You can
-learn more about the behavior of `x-datadog-sampling-priority` in the [Datadog
-priority sampling documentation].
+In distributed tracing, multiple processes contribute to the same trace.
 
-[Datadog priority sampling documentation]: https://docs.datadoghq.com/tracing/getting_further/trace_sampling_and_storage/#priority-sampling-for-distributed-tracing
+That is handled in this adapter by `SpandexDatadog.Adapter.distributed_context/2` and
+`SpandexDatadog.Adapter.inject_context/3`, which read and generate Datadog-specific
+HTTP headers based on the state of the trace. If these headers are set, the
+trace will be continued instead of starting a new one.
+They are called by [spandex_phoenix](https://github.com/spandex-project/spandex_phoenix)
+when receiving a request and by your own HTTP requests to downstream services.
+
+## Sampling and Rate Limiting
+
+When the load or cost from tracing increases, it is useful to use sampling or
+rate limiting to reduce tracing. When many traces are the same, it's enough to
+trace only e.g. 10% of them, reducing the bill by 90% while still preserving
+the ability to troubleshoot the system.
+
+With sampling, the tracing still happens, but Datadog may drop it or not
+retain detailed information. This keeps metrics such as the number of requests
+correct, even without detailed trace data.
+
+This adapter supports distributed trace sampling according to the new Datadog
+[ingestion controls](https://docs.datadoghq.com/tracing/trace_pipeline/ingestion_controls/).
+
+Spandex stores the `priority` as an integer in the top level `Spandex.Trace`.
+
+In Datadog, there are four values:
+* `USER_KEEP`(2) indicates that the application wants to ensure that a trace is
+  sampled, e.g. if there is an error
+* `AUTO_KEEP` (1) indicates that a trace has been selected for sampling
+* `AUTO_REJECT` (0) indicates that the trace has not been selected for sampling
+* `USER_REJECT` (-1) indicates that the application wants a trace to be dropped
+
+Datadog uses the `x-datadog-sampling-priority` header to determine whether a
+trace should be sampled. See the [Datadog documentation]:
+https://docs.datadoghq.com/tracing/getting_further/trace_sampling_and_storage/#priority-sampling-for-distributed-tracing
+
+When sampling, the process that starts the trace can make a decision about
+whether it should be sampled. It then passes that information to downstream
+processes via the HTTP headers.
+
+In distributed tracing, the priority may be set as follows:
+
+* Set the priority based on the `x-datadog-sampling-priority` header on the
+  inbound request, propagating it to downstream http requests.
+
+* If no priority header is present (i.e. this is the first app in the trace),
+  make a sampling decision and set the `priority` to 0 or 1 on the current trace.
+  `SpandexDatadog.RateSampler.sampled?/2` supports sampling a proportion of
+  traces based on the `trace_id` (which should be assigned randomly).  This would
+  typically be called from in a Phoenix `plug`, which then sets the priority to 1
+  on the current trace using Spandex.Tracer.update_priority/2`.
+
+* Force tracking manually by setting priority to 2 on the trace in application
+  code. This is usually done for requests with errors, as they are the ones
+  that need troubleshooting. You can also enable tracing dynamically with a
+  feature flag to debug a feature in production. This overrides whatever sampling
+  decision was made upstream, and Datadog will keep the complete trace.
+
+Older versions of Datadog used rate sampling to tune the priority of spans, but
+those are considered obsolete. You can still set them by adding tags to spans:
+
+* Use `sample_rate` tag to set "_dd1.sr.eausr"
+* Use `rule_sample_rate` tag to set "_dd.rule_psr" without default (previously
+  hard coded to 1.0)
+* Use `rate_limiter_rate` tag to set "_dd.limit_psr", without default
+  (previously hard coded to 1.0)
+* Use `agent_sample_rate` tag to set "_dd.agent_psr" without default (was 1.0)
 
 ## Telemetry
 
@@ -145,22 +201,23 @@ per trace, then you probably want to keep that number low. If you send only a
 few spans, then you could set it significantly higher.
 
 Sync threshold is how many _simultaneous_ HTTP pushes will be going to Datadog
-before it blocks/throttles your application by making the tracing call synchronous instead of async.
+before it blocks/throttles your application by making the tracing call
+synchronous instead of async.
 
-Ideally, the sync threshold would be set to a point that you wouldn't reasonably reach often, but
-that is low enough to not cause systemic performance issues if you don't apply
+Ideally, the sync threshold would be set to a point that you wouldn't
+reasonably reach often, but that is low enough to not cause systemic
+performance issues if you don't apply
 backpressure.
 
-A simple way to think about it is that if you are seeing 1000
-request per second and `batch_size` is 10, then you'll be making 100
-requests per second to Datadog (probably a bad config).
-With `sync_threshold` set to 10, only 10 of those requests can be
-processed concurrently before trace calls become synchronous.
-
-This concept of backpressure is very important, and strategies
-for switching to synchronous operation are often surprisingly far more
-performant than purely asynchronous strategies (and much more predictable).
+A simple way to think about it is that if you are seeing 1000 request per
+second and `batch_size` is 10, then you'll be making 100 requests per second to
+Datadog (probably a bad config).  With `sync_threshold` set to 10, only 10 of
+those requests can be processed concurrently before trace calls become
+synchronous.
 
+This concept of backpressure is very important, and strategies for switching to
+synchronous operation are often surprisingly far more performant than purely
+asynchronous strategies (and much more predictable).
 
 ## Copyright and License
 

From f1e64a2d89155d057d32bdac352859c401042b22 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Mon, 22 Aug 2022 12:20:23 -0500
Subject: [PATCH 26/44] Fix quotes

---
 README.md | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index a53a6d7..335798c 100644
--- a/README.md
+++ b/README.md
@@ -101,7 +101,7 @@ In distributed tracing, the priority may be set as follows:
   `SpandexDatadog.RateSampler.sampled?/2` supports sampling a proportion of
   traces based on the `trace_id` (which should be assigned randomly).  This would
   typically be called from in a Phoenix `plug`, which then sets the priority to 1
-  on the current trace using Spandex.Tracer.update_priority/2`.
+  on the current trace using `Spandex.Tracer.update_priority/2`.
 
 * Force tracking manually by setting priority to 2 on the trace in application
   code. This is usually done for requests with errors, as they are the ones
@@ -112,12 +112,12 @@ In distributed tracing, the priority may be set as follows:
 Older versions of Datadog used rate sampling to tune the priority of spans, but
 those are considered obsolete. You can still set them by adding tags to spans:
 
-* Use `sample_rate` tag to set "_dd1.sr.eausr"
-* Use `rule_sample_rate` tag to set "_dd.rule_psr" without default (previously
+* Use `sample_rate` tag to set `_dd1.sr.eausr`
+* Use `rule_sample_rate` tag to set `_dd.rule_psr` without default (previously
   hard coded to 1.0)
-* Use `rate_limiter_rate` tag to set "_dd.limit_psr", without default
+* Use `rate_limiter_rate` tag to set `_dd.limit_psr`, without default
   (previously hard coded to 1.0)
-* Use `agent_sample_rate` tag to set "_dd.agent_psr" without default (was 1.0)
+* Use `agent_sample_rate` tag to set `_dd.agent_psr` without default (was 1.0)
 
 ## Telemetry
 

From e0618f2fcbe678deab1345ffc526cc015ac07ae4 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Mon, 22 Aug 2022 12:51:58 -0500
Subject: [PATCH 27/44] Use new names for priority constants

---
 README.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 335798c..381d0ec 100644
--- a/README.md
+++ b/README.md
@@ -77,11 +77,11 @@ This adapter supports distributed trace sampling according to the new Datadog
 Spandex stores the `priority` as an integer in the top level `Spandex.Trace`.
 
 In Datadog, there are four values:
-* `USER_KEEP`(2) indicates that the application wants to ensure that a trace is
+* `MANUAL_KEEP`(2) indicates that the application wants to ensure that a trace is
   sampled, e.g. if there is an error
 * `AUTO_KEEP` (1) indicates that a trace has been selected for sampling
 * `AUTO_REJECT` (0) indicates that the trace has not been selected for sampling
-* `USER_REJECT` (-1) indicates that the application wants a trace to be dropped
+* `MANUAL_REJECT` (-1) indicates that the application wants a trace to be dropped
 
 Datadog uses the `x-datadog-sampling-priority` header to determine whether a
 trace should be sampled. See the [Datadog documentation]:

From dac254a44ceaaa6fd3f7bafacf96b5d56ec9c7de Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Mon, 22 Aug 2022 12:52:13 -0500
Subject: [PATCH 28/44] Add constants for priority

---
 lib/spandex_datadog/constants.ex | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 lib/spandex_datadog/constants.ex

diff --git a/lib/spandex_datadog/constants.ex b/lib/spandex_datadog/constants.ex
new file mode 100644
index 0000000..06296dc
--- /dev/null
+++ b/lib/spandex_datadog/constants.ex
@@ -0,0 +1,31 @@
+defmodule SpandexDatadog.Constants do
+  @moduledoc """
+  Defines constants used in Datadog API.
+  """
+
+  @doc """
+  `priority` value `MANUAL_KEEP` (2) indicates that the application wants to ensure
+  that a trace is sampled, e.g. if there is an error.
+
+  See https://docs.datadoghq.com/tracing/getting_further/trace_sampling_and_storage/#priority-sampling-for-distributed-tracing
+  """
+  def manual_keep, do: 2
+
+  @doc """
+  `priority` value `AUTO_KEEP` (1) indicates that a trace has been selected for
+  sampling.
+  """
+  def auto_keep, do: 1
+
+  @doc """
+  `priority` value `AUTO_REJECT` (0) indicates that the trace has not been
+  selected for sampling.
+  """
+  def auto_reject, do: 1
+
+  @doc """
+  `priority` value `MANUAL_REJECT` (-1) indicates that the application wants a
+  trace to be dropped.
+  """
+  def manual_reject, do: -1
+end

From 5b3a75801dc5fbe05b4415c22ca0260be1d71d7f Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 23 Aug 2022 13:26:56 -0500
Subject: [PATCH 29/44] Doc

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index 381d0ec..2db302c 100644
--- a/README.md
+++ b/README.md
@@ -57,7 +57,7 @@ That is handled in this adapter by `SpandexDatadog.Adapter.distributed_context/2
 `SpandexDatadog.Adapter.inject_context/3`, which read and generate Datadog-specific
 HTTP headers based on the state of the trace. If these headers are set, the
 trace will be continued instead of starting a new one.
-They are called by [spandex_phoenix](https://github.com/spandex-project/spandex_phoenix)
+These functions are called in [spandex_phoenix](https://github.com/spandex-project/spandex_phoenix)
 when receiving a request and by your own HTTP requests to downstream services.
 
 ## Sampling and Rate Limiting

From bd2f7ac58c1ec84bcc9fff483df6335611519f15 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 23 Aug 2022 13:27:22 -0500
Subject: [PATCH 30/44] Add GitHub Actions

---
 .github/workflows/ci.yml | 61 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 .github/workflows/ci.yml

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..b28a96a
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,61 @@
+name: CI
+on: push
+
+jobs:
+  elixir:
+    name: Elixir Tests
+    runs-on: ubuntu-20.04
+
+    steps:
+      - name: Cancel Previous Runs
+        uses: styfle/cancel-workflow-action@0.5.0
+        with:
+          access_token: ${{ github.token }}
+
+      - name: Checkout Code
+        uses: actions/checkout@v2.3.1
+
+      - name: Setup Elixir
+        uses: actions/setup-elixir@v1.5.0
+        with:
+          otp-version: 24.3.4
+          elixir-version: 1.13.4
+          experimental-otp: true
+
+      - name: Retrieve Cached Dependencies
+        id: mix-cache
+        uses: actions/cache@v2
+        with:
+          path: |
+            deps
+            _build
+          key: ${{ runner.os }}-mix-${{ hashFiles('**/mix.lock') }}
+          restore-keys: |
+            ${{ runner.os }}-mix-
+
+      - name: Install Dependencies
+        run: |
+          mix local.rebar --force
+          mix local.hex --force
+          mix deps.get
+
+      - name: Check Formatting
+        run: mix format --check-formatted
+
+      - name: Compile Code
+        env:
+          MIX_ENV: test
+        run: |
+          mix compile --warnings-as-errors
+
+      - name: Run Tests
+        run: |
+          # mix test --warnings-as-errors
+          mix test
+
+      # - name: Publish unit test results to GitHub
+      #   uses: EnricoMi/publish-unit-test-result-action@v1
+      #   if: always() # always run even if tests fail
+      #   with:
+      #     files: _build/test/lib/*/test-junit-report.xml
+

From 2aa894bf32711af370562ba62036f68a1843ebab Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 23 Aug 2022 13:32:38 -0500
Subject: [PATCH 31/44] mix format

---
 lib/spandex_datadog/rate_sampler.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/spandex_datadog/rate_sampler.ex b/lib/spandex_datadog/rate_sampler.ex
index ed940a5..90dba25 100644
--- a/lib/spandex_datadog/rate_sampler.ex
+++ b/lib/spandex_datadog/rate_sampler.ex
@@ -8,7 +8,7 @@ defmodule SpandexDatadog.RateSampler do
   # system may generate one.
   @external_max_id Bitwise.bsl(1, 64)
 
-  @knuth_factor 1111111111111111111
+  @knuth_factor 1_111_111_111_111_111_111
 
   @doc """
   Determine whether a trace should be sampled.

From a4c87d146aa719a34fdc287c8103984266c7366a Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 23 Aug 2022 14:02:05 -0500
Subject: [PATCH 32/44] Enable --warnings-as-errors

---
 .github/workflows/ci.yml | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b28a96a..f80f6d9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -50,8 +50,7 @@ jobs:
 
       - name: Run Tests
         run: |
-          # mix test --warnings-as-errors
-          mix test
+          mix test --warnings-as-errors
 
       # - name: Publish unit test results to GitHub
       #   uses: EnricoMi/publish-unit-test-result-action@v1

From 418834d6828de08a77aa08e4cff37b321e0139b3 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 23 Aug 2022 14:44:55 -0500
Subject: [PATCH 33/44] Add :file and :line to logger metadata for tests

---
 config/test.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/config/test.exs b/config/test.exs
index 526e7bd..f00696b 100644
--- a/config/test.exs
+++ b/config/test.exs
@@ -4,7 +4,7 @@ config :logger, :console,
   level: :debug,
   colors: [enabled: false],
   format: "$time $metadata[$level] $message\n",
-  metadata: [:trace_id, :span_id]
+  metadata: [:trace_id, :span_id, :file, :line]
 
 config :spandex_datadog, SpandexDatadog.Test.Support.Tracer,
   service: :spandex_test,

From 257451ccb301bb1fe4b25278e4ca443558dade15 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 23 Aug 2022 15:12:08 -0500
Subject: [PATCH 34/44] Run mix format check after deps.get

---
 .circleci/config.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.circleci/config.yml b/.circleci/config.yml
index 343e4dd..3db92d5 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -13,7 +13,7 @@ jobs:
       - checkout
       - run: mix local.hex --force
       - run: mix local.rebar --force
-      - run: mix format --check-formatted
       - run: mix deps.get
+      - run: mix format --check-formatted
       - run: mix compile --warnings-as-errors
       - run: mix test

From 78c01a30f84d3e36151dc383ccd1fbc0fda6672e Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Tue, 23 Aug 2022 15:16:38 -0500
Subject: [PATCH 35/44] Require Elixir 1.11

---
 mix.exs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mix.exs b/mix.exs
index 34819b1..1e2f586 100644
--- a/mix.exs
+++ b/mix.exs
@@ -10,7 +10,7 @@ defmodule SpandexDatadog.MixProject do
       deps: deps(),
       description: "A datadog API adapter for spandex.",
       docs: docs(),
-      elixir: "~> 1.6",
+      elixir: "~> 1.11",
       elixirc_paths: elixirc_paths(Mix.env()),
       package: package(),
       start_permanent: Mix.env() == :prod,

From 968aa6b4e229d4b5d7404ca12a40f66d50786d43 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Wed, 24 Aug 2022 13:38:17 -0500
Subject: [PATCH 36/44] Test older versions of Elixir

---
 .github/workflows/ci.yml | 53 ++++++++++++++++++++--------------------
 1 file changed, 27 insertions(+), 26 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f80f6d9..8822909 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,3 +1,4 @@
+---
 name: CI
 on: push
 
@@ -5,56 +6,56 @@ jobs:
   elixir:
     name: Elixir Tests
     runs-on: ubuntu-20.04
-
+    env:
+      MIX_ENV: test
+    strategy:
+      matrix:
+        elixir: ['1.11', '1.13.4']
+        otp: ['24', '25']
     steps:
-      - name: Cancel Previous Runs
+      - name: Cancel previous runs
         uses: styfle/cancel-workflow-action@0.5.0
         with:
           access_token: ${{ github.token }}
 
-      - name: Checkout Code
-        uses: actions/checkout@v2.3.1
+      - name: Checkout code
+        uses: actions/checkout@v2
 
       - name: Setup Elixir
-        uses: actions/setup-elixir@v1.5.0
+        uses: actions/setup-beam@v1
+        with:
+          otp-version: ${{ matrix.otp }}
+          elixir-version: ${{ matrix.otp }}
+
+      - name: Get deps cache
+        uses: actions/cache@v2
         with:
-          otp-version: 24.3.4
-          elixir-version: 1.13.4
-          experimental-otp: true
+          path: deps/
+          key: deps-${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('**/mix.lock') }}
 
-      - name: Retrieve Cached Dependencies
-        id: mix-cache
+      - name: Get build cache
         uses: actions/cache@v2
         with:
-          path: |
-            deps
-            _build
-          key: ${{ runner.os }}-mix-${{ hashFiles('**/mix.lock') }}
-          restore-keys: |
-            ${{ runner.os }}-mix-
-
-      - name: Install Dependencies
+          path: _build/test/
+          key: build-${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('**/mix.lock') }}
+
+      - name: Install deps
         run: |
           mix local.rebar --force
           mix local.hex --force
           mix deps.get
 
-      - name: Check Formatting
-        run: mix format --check-formatted
-
-      - name: Compile Code
-        env:
-          MIX_ENV: test
+      - name: Compile code
         run: |
           mix compile --warnings-as-errors
 
-      - name: Run Tests
+      - name: Run tests
         run: |
           mix test --warnings-as-errors
+          mix format --check-formatted
 
       # - name: Publish unit test results to GitHub
       #   uses: EnricoMi/publish-unit-test-result-action@v1
       #   if: always() # always run even if tests fail
       #   with:
       #     files: _build/test/lib/*/test-junit-report.xml
-

From ba93460bd2ec7166ea8cb2f4c4ce1fde267a749f Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Wed, 24 Aug 2022 15:30:48 -0500
Subject: [PATCH 37/44] Use setup-elixir instead of setup-beam

---
 .github/workflows/ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8822909..05739fb 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,7 +22,7 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Setup Elixir
-        uses: actions/setup-beam@v1
+        uses: actions/setup-elixir@v1
         with:
           otp-version: ${{ matrix.otp }}
           elixir-version: ${{ matrix.otp }}

From 4ace750173ad586826e5999803c1a28264f46f20 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Wed, 24 Aug 2022 15:37:57 -0500
Subject: [PATCH 38/44] Use newer version of setup-elixir

---
 .github/workflows/ci.yml | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 05739fb..6fcc67f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,10 +22,11 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Setup Elixir
-        uses: actions/setup-elixir@v1
+        uses: actions/setup-elixir@v1.5.0
         with:
           otp-version: ${{ matrix.otp }}
           elixir-version: ${{ matrix.otp }}
+          experimental-otp: true
 
       - name: Get deps cache
         uses: actions/cache@v2
@@ -55,7 +56,7 @@ jobs:
           mix format --check-formatted
 
       # - name: Publish unit test results to GitHub
-      #   uses: EnricoMi/publish-unit-test-result-action@v1
+      #   uses: EnricoMi/publish-unit-test-result-action@v2
       #   if: always() # always run even if tests fail
       #   with:
-      #     files: _build/test/lib/*/test-junit-report.xml
+      #     junit_files: _build/test/lib/*/test-junit-report.xml

From 2c22a7ff1b4f16714bdca22cf1a84553877d776f Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Wed, 24 Aug 2022 15:55:56 -0500
Subject: [PATCH 39/44] Specify detailed versions of Elixir and OTP

---
 .github/workflows/ci.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6fcc67f..3d1ab21 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -10,8 +10,8 @@ jobs:
       MIX_ENV: test
     strategy:
       matrix:
-        elixir: ['1.11', '1.13.4']
-        otp: ['24', '25']
+        elixir: ['1.11.4', '1.13.4']
+        otp: ['24.3.4', '25.0.4']
     steps:
       - name: Cancel previous runs
         uses: styfle/cancel-workflow-action@0.5.0

From 7d903be4820d2b8358b9425817a3ee90b6b405f3 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Wed, 24 Aug 2022 16:02:50 -0500
Subject: [PATCH 40/44] Fix variable

---
 .github/workflows/ci.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3d1ab21..03dd043 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         elixir: ['1.11.4', '1.13.4']
-        otp: ['24.3.4', '25.0.4']
+        otp: ['24.3', '25.0']
     steps:
       - name: Cancel previous runs
         uses: styfle/cancel-workflow-action@0.5.0
@@ -25,7 +25,7 @@ jobs:
         uses: actions/setup-elixir@v1.5.0
         with:
           otp-version: ${{ matrix.otp }}
-          elixir-version: ${{ matrix.otp }}
+          elixir-version: ${{ matrix.elixir }}
           experimental-otp: true
 
       - name: Get deps cache

From dd69b3003c66a46dd8bba93a5a7785d8b056a94a Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Thu, 25 Aug 2022 11:30:03 -0500
Subject: [PATCH 41/44] Use erlef/setup-beam; only build on OTP 24

---
 .github/workflows/ci.yml | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 03dd043..cb231f2 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -11,7 +11,7 @@ jobs:
     strategy:
       matrix:
         elixir: ['1.11.4', '1.13.4']
-        otp: ['24.3', '25.0']
+        otp: ['24.3']
     steps:
       - name: Cancel previous runs
         uses: styfle/cancel-workflow-action@0.5.0
@@ -22,11 +22,10 @@ jobs:
         uses: actions/checkout@v2
 
       - name: Setup Elixir
-        uses: actions/setup-elixir@v1.5.0
+        uses: erlef/setup-beam@v1
         with:
           otp-version: ${{ matrix.otp }}
           elixir-version: ${{ matrix.elixir }}
-          experimental-otp: true
 
       - name: Get deps cache
         uses: actions/cache@v2

From 4d018cbbbf4f7beebe290ec608e383f08ff9039c Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Thu, 25 Aug 2022 11:42:02 -0500
Subject: [PATCH 42/44] Remove invalid --warnings-as-errors option

---
 .github/workflows/ci.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index cb231f2..79a6381 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -51,7 +51,7 @@ jobs:
 
       - name: Run tests
         run: |
-          mix test --warnings-as-errors
+          mix test
           mix format --check-formatted
 
       # - name: Publish unit test results to GitHub

From 6fd650dede4da13994974abd8466473fa60ef652 Mon Sep 17 00:00:00 2001
From: Jake Morrison <jake.morrison@therealreal.com>
Date: Thu, 25 Aug 2022 11:44:28 -0500
Subject: [PATCH 43/44] Use latest syntax

---
 .circleci/config.yml | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/.circleci/config.yml b/.circleci/config.yml
index 3db92d5..34a931c 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -1,7 +1,7 @@
-# Elixir CircleCI 2.0 configuration file
-#
+---
+# CircleCI 2.0 configuration file
 # Check https://circleci.com/docs/2.0/language-elixir/ for more details
-version: 2
+version: 2.1
 jobs:
   build:
     docker:

From 71cda32bb2f9bf9a48f078b8a4b9e8b3a997d7e9 Mon Sep 17 00:00:00 2001
From: Jake Morrison <accounts@jakemorrison.com>
Date: Fri, 9 Sep 2022 03:33:10 +0800
Subject: [PATCH 44/44] Update lib/spandex_datadog/adapter.ex

Co-authored-by: Greg Mefford <greg@gregmefford.com>
---
 lib/spandex_datadog/adapter.ex | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/spandex_datadog/adapter.ex b/lib/spandex_datadog/adapter.ex
index 70499cb..30a30e0 100644
--- a/lib/spandex_datadog/adapter.ex
+++ b/lib/spandex_datadog/adapter.ex
@@ -112,7 +112,7 @@ defmodule SpandexDatadog.Adapter do
   end
 
   # Based on the code of the Ruby libary, it seems valid
-  # to have onlly the trace_id and origin headers set, but not parent_id.
+  # to have only the trace_id and origin headers set, but not parent_id.
   # This might happen with RUM or synthetic traces.
   defp validate_context(%{parent_id: nil} = span_context) do
     if Keyword.has_key?(span_context.baggage, :"_dd.origin") do