From 84ba8c747339a078c67dda4e62657a9afb4fdbfa Mon Sep 17 00:00:00 2001
From: Simon Cruanes <simon.cruanes.2007@m4x.org>
Date: Mon, 12 Feb 2024 13:44:02 -0500
Subject: [PATCH] add dummy values for span/trace id, and for span_ctx

---
 src/core/opentelemetry.ml | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/core/opentelemetry.ml b/src/core/opentelemetry.ml
index 67e076f0..e3940f15 100644
--- a/src/core/opentelemetry.ml
+++ b/src/core/opentelemetry.ml
@@ -271,6 +271,8 @@ module Trace_id : sig
 
   val create : unit -> t
 
+  val dummy : t
+
   val pp : Format.formatter -> t -> unit
 
   val is_valid : t -> bool
@@ -291,6 +293,8 @@ end = struct
 
   let to_bytes self = self
 
+  let dummy : t = Bytes.make 16 '\x00'
+
   let create () : t =
     let b = Collector.rand_bytes_16 () in
     assert (Bytes.length b = 16);
@@ -324,6 +328,8 @@ module Span_id : sig
 
   val create : unit -> t
 
+  val dummy : t
+
   val pp : Format.formatter -> t -> unit
 
   val is_valid : t -> bool
@@ -344,6 +350,8 @@ end = struct
 
   let to_bytes self = self
 
+  let dummy : t = Bytes.make 8 '\x00'
+
   let create () : t =
     let b = Collector.rand_bytes_8 () in
     assert (Bytes.length b = 8);
@@ -373,12 +381,16 @@ end
 
 (** Span context. This bundles up a trace ID and parent ID.
 
-    https://opentelemetry.io/docs/specs/otel/trace/api/#spancontext *)
+    https://opentelemetry.io/docs/specs/otel/trace/api/#spancontext
+    @since NEXT_RELEASE *)
 module Span_ctx : sig
   type t
 
   val make : trace_id:Trace_id.t -> parent_id:Span_id.t -> unit -> t
 
+  val dummy : t
+  (** Invalid span context, to be used as a placeholder *)
+
   val is_valid : t -> bool
 
   val trace_id : t -> Trace_id.t
@@ -403,6 +415,9 @@ end = struct
     is_remote: bool;
   }
 
+  let dummy =
+    { trace_id = Trace_id.dummy; parent_id = Span_id.dummy; is_remote = false }
+
   let make ~trace_id ~parent_id () : t =
     { trace_id; parent_id; is_remote = false }