From 2bb0995ff8524c4aeb20483003a38fdcc7429bad Mon Sep 17 00:00:00 2001
From: Pratik Mankawde <3397372+pratikmankawde@users.noreply.github.com>
Date: Mon, 27 Apr 2026 14:48:07 +0100
Subject: [PATCH] fix(telemetry): use default_prng() for span IDs, fix
 non-telemetry build
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Replace thread_local mt19937 with xrpl::default_prng() for span ID
generation — uses the project's existing thread-local xor-shift engine.
One call yields a uint64_t (8 bytes), filling the span ID in a single
memcpy without loops.

Fix compilation failure when XRPL_ENABLE_TELEMETRY is not defined:
move xrpl.pb.h include outside the #ifdef guard in TxTracing.h since
protocol::TMTransaction is used unconditionally in the function
signature.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---
 src/libxrpl/telemetry/SpanGuard.cpp | 8 ++++----
 src/xrpld/telemetry/TxTracing.h     | 5 +----
 2 files changed, 5 insertions(+), 8 deletions(-)

diff --git a/src/libxrpl/telemetry/SpanGuard.cpp b/src/libxrpl/telemetry/SpanGuard.cpp
index a2cbfe5ec6..3d3f52ca29 100644
--- a/src/libxrpl/telemetry/SpanGuard.cpp
+++ b/src/libxrpl/telemetry/SpanGuard.cpp
@@ -20,6 +20,7 @@
 
 #ifdef XRPL_ENABLE_TELEMETRY
 
+#include <xrpl/basics/random.h>
 #include <xrpl/telemetry/DiscardFlag.h>
 #include <xrpl/telemetry/SpanGuard.h>
 #include <xrpl/telemetry/SpanNames.h>
@@ -38,7 +39,7 @@
 #include <opentelemetry/trace/trace_id.h>
 #include <opentelemetry/trace/tracer.h>
 
-#include <random>
+#include <cstring>
 #include <string>
 #include <utility>
 
@@ -248,10 +249,9 @@ SpanGuard::txSpan(
 
     otel_trace::TraceId traceId(opentelemetry::nostd::span<std::uint8_t const, 16>(hashData, 16));
 
+    auto const rval = default_prng()();
     std::uint8_t spanIdBytes[8];
-    thread_local std::mt19937 prng{std::random_device{}()};
-    for (auto& b : spanIdBytes)
-        b = static_cast<std::uint8_t>(prng());
+    std::memcpy(spanIdBytes, &rval, sizeof(spanIdBytes));
     otel_trace::SpanId spanId(opentelemetry::nostd::span<std::uint8_t const, 8>(spanIdBytes, 8));
 
     otel_trace::SpanContext syntheticCtx(
diff --git a/src/xrpld/telemetry/TxTracing.h b/src/xrpld/telemetry/TxTracing.h
index d99163ee53..9cb0f296a6 100644
--- a/src/xrpld/telemetry/TxTracing.h
+++ b/src/xrpld/telemetry/TxTracing.h
@@ -13,11 +13,8 @@
 #include <xrpld/app/misc/TxSpanNames.h>
 
 #include <xrpl/basics/base_uint.h>
-#include <xrpl/telemetry/SpanGuard.h>
-
-#ifdef XRPL_ENABLE_TELEMETRY
 #include <xrpl/proto/xrpl.pb.h>
-#endif
+#include <xrpl/telemetry/SpanGuard.h>
 
 namespace xrpl {
 namespace telemetry {