From 83457e7cc3c2879dc6b469ad6b16e473a4071aa5 Mon Sep 17 00:00:00 2001
From: Pratik Mankawde <3397372+pratikmankawde@users.noreply.github.com>
Date: Thu, 6 Aug 2026 15:38:44 +0100
Subject: [PATCH 1/2] test: Make Drop50 message drop deterministic in
 LedgerReplayer test

The 'network drops 50% messages' testcase dropped each request with an
independent random 50% probability. A subtask permanently fails after
1 + kSubTaskMaxTimeouts (11) consecutive dropped sends, so each run had
a ~1/512 chance of failure, causing intermittent CI failures at
LedgerReplay_test.cpp(1340) and (1342).

Drop every other message via a counter instead. This still exercises
the timeout/retry path but guarantees every subtask eventually gets a
reply.
---
 src/test/app/LedgerReplay_test.cpp | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/src/test/app/LedgerReplay_test.cpp b/src/test/app/LedgerReplay_test.cpp
index 7b521402a40..ab4dbe72849 100644
--- a/src/test/app/LedgerReplay_test.cpp
+++ b/src/test/app/LedgerReplay_test.cpp
@@ -28,7 +28,6 @@
 
 #include <xrpl/basics/Slice.h>
 #include <xrpl/basics/base_uint.h>
-#include <xrpl/basics/random.h>
 #include <xrpl/beast/net/IPAddress.h>
 #include <xrpl/beast/net/IPEndpoint.h>
 #include <xrpl/beast/unit_test/suite.h>
@@ -53,6 +52,7 @@
 #include <xrpl.pb.h>
 
 #include <algorithm>
+#include <atomic>
 #include <cassert>
 #include <chrono>
 #include <cstddef>
@@ -443,17 +443,16 @@ struct TestPeerSet : public PeerSet
         protocol::MessageType type,
         std::shared_ptr<Peer> const& peer) override
     {
-        int dropRate = 0;
-        if (behavior == PeerSetBehavior::Drop50)
-        {
-            dropRate = 50;
-        }
-        else if (behavior == PeerSetBehavior::DropAll)
-        {
-            dropRate = 100;
-        }
+        if (behavior == PeerSetBehavior::DropAll)
+            return;
 
-        if (randInt(1, 100) <= dropRate)
+        // Drop every other message deterministically. A random 50% drop
+        // could drop all (1 + kSubTaskMaxTimeouts) sends of a subtask
+        // (probability (1/2)^11 per subtask), failing the whole task and
+        // making the test flaky. Alternating drops still exercise the
+        // timeout/retry path while guaranteeing every subtask eventually
+        // gets a reply.
+        if (behavior == PeerSetBehavior::Drop50 && sendCount++ % 2 == 0)
             return;
 
         switch (type)
@@ -498,6 +497,7 @@ struct TestPeerSet : public PeerSet
     LedgerReplayMsgHandler& remote;
     std::shared_ptr<TestPeer> dummyPeer;
     PeerSetBehavior behavior;
+    std::atomic<int> sendCount{0};
 };
 
 /**

From 54547c76fdcacf1d4a9954736c8b385dd2c97840 Mon Sep 17 00:00:00 2001
From: Pratik Mankawde <3397372+pratikmankawde@users.noreply.github.com>
Date: Fri, 7 Aug 2026 11:25:48 +0100
Subject: [PATCH 2/2] minor comment update

Signed-off-by: Pratik Mankawde <3397372+pratikmankawde@users.noreply.github.com>
---
 src/test/app/LedgerReplay_test.cpp | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/src/test/app/LedgerReplay_test.cpp b/src/test/app/LedgerReplay_test.cpp
index ab4dbe72849..adc8c7b3241 100644
--- a/src/test/app/LedgerReplay_test.cpp
+++ b/src/test/app/LedgerReplay_test.cpp
@@ -446,12 +446,9 @@ struct TestPeerSet : public PeerSet
         if (behavior == PeerSetBehavior::DropAll)
             return;
 
-        // Drop every other message deterministically. A random 50% drop
-        // could drop all (1 + kSubTaskMaxTimeouts) sends of a subtask
-        // (probability (1/2)^11 per subtask), failing the whole task and
-        // making the test flaky. Alternating drops still exercise the
-        // timeout/retry path while guaranteeing every subtask eventually
-        // gets a reply.
+        // Drop every other message deterministically. Alternating drops
+        // still exercise the timeout/retry path while guaranteeing every
+        // subtask eventually gets a reply.
         if (behavior == PeerSetBehavior::Drop50 && sendCount++ % 2 == 0)
             return;