From 467d8a4a4bd06ca2e6bce3ba773ed37b231d7f60 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?S=C3=A9bastien=20Deronne?= <sebastien.deronne@gmail.com>
Date: Thu, 6 Jun 2024 22:56:25 +0200
Subject: [PATCH] applications: UdpTraceClient reload traces when remote
 address is changed

This avoids to clear the trace entries without repopulating them with the currently selected trace file
---
 src/applications/model/udp-trace-client.cc | 49 ++++++++++++----------
 src/applications/model/udp-trace-client.h  |  6 +--
 2 files changed, 30 insertions(+), 25 deletions(-)

diff --git a/src/applications/model/udp-trace-client.cc b/src/applications/model/udp-trace-client.cc
index 6f0506153..49b5c223b 100644
--- a/src/applications/model/udp-trace-client.cc
+++ b/src/applications/model/udp-trace-client.cc
@@ -150,12 +150,12 @@ UdpTraceClient::SetRemote(const Address& addr)
     NS_LOG_FUNCTION(this << addr);
     if (!addr.IsInvalid())
     {
-        m_entries.clear();
         m_peer = addr;
         if (m_peerPort)
         {
             SetPort(*m_peerPort);
         }
+        LoadTrace();
     }
 }
 
@@ -203,14 +203,8 @@ void
 UdpTraceClient::SetTraceFile(const std::string& traceFile)
 {
     NS_LOG_FUNCTION(this << traceFile);
-    if (traceFile.empty())
-    {
-        LoadDefaultTrace();
-    }
-    else
-    {
-        LoadTrace(traceFile);
-    }
+    m_traceFile = traceFile;
+    LoadTrace();
 }
 
 void
@@ -228,30 +222,42 @@ UdpTraceClient::GetMaxPacketSize()
 }
 
 void
-UdpTraceClient::LoadTrace(const std::string& filename)
+UdpTraceClient::LoadTrace()
 {
-    NS_LOG_FUNCTION(this << filename);
-    uint32_t time = 0;
-    uint32_t index = 0;
-    uint32_t oldIndex = 0;
-    uint32_t size = 0;
-    uint32_t prevTime = 0;
-    char frameType;
-    TraceEntry entry;
-    std::ifstream ifTraceFile;
-    ifTraceFile.open(filename, std::ifstream::in);
+    NS_LOG_FUNCTION(this);
     m_entries.clear();
+    m_currentEntry = 0;
+
+    if (m_traceFile.empty())
+    {
+        LoadDefaultTrace();
+        return;
+    }
+
+    std::ifstream ifTraceFile;
+    ifTraceFile.open(m_traceFile, std::ifstream::in);
     if (!ifTraceFile.good())
     {
         LoadDefaultTrace();
+        return;
     }
+
+    uint32_t oldIndex = 0;
+    uint32_t prevTime = 0;
     while (ifTraceFile.good())
     {
+        uint32_t index = 0;
+        char frameType;
+        uint32_t time = 0;
+        uint32_t size = 0;
         ifTraceFile >> index >> frameType >> time >> size;
+
         if (index == oldIndex)
         {
             continue;
         }
+
+        TraceEntry entry{};
         if (frameType == 'B')
         {
             entry.timeToSend = 0;
@@ -266,9 +272,9 @@ UdpTraceClient::LoadTrace(const std::string& filename)
         m_entries.push_back(entry);
         oldIndex = index;
     }
+
     ifTraceFile.close();
     NS_ASSERT_MSG(prevTime != 0, "A trace file can not contain B frames only.");
-    m_currentEntry = 0;
 }
 
 void
@@ -291,7 +297,6 @@ UdpTraceClient::LoadDefaultTrace()
         }
         m_entries.push_back(entry);
     }
-    m_currentEntry = 0;
 }
 
 void
diff --git a/src/applications/model/udp-trace-client.h b/src/applications/model/udp-trace-client.h
index 9e2b2b2d9..59f0a711c 100644
--- a/src/applications/model/udp-trace-client.h
+++ b/src/applications/model/udp-trace-client.h
@@ -128,10 +128,9 @@ class UdpTraceClient : public Application
     Address GetRemote() const;
 
     /**
-     * \brief Load a trace file
-     * \param filename the trace file path
+     * \brief Load current trace file
      */
-    void LoadTrace(const std::string& filename);
+    void LoadTrace();
 
     /**
      * \brief Load the default trace
@@ -174,6 +173,7 @@ class UdpTraceClient : public Application
     static TraceEntry g_defaultEntries[]; //!< Default trace to send
     uint16_t m_maxPacketSize; //!< Maximum packet size to send (including the SeqTsHeader)
     bool m_traceLoop;         //!< Loop through the trace file
+    std::string m_traceFile;  //!< The location of the trace file
 };
 
 } // namespace ns3