* [Core] Fix race condition in CSampleSender::Send() #1332 (#1333)

This PR protects the m_payload member variable and thus makes the Send() function reentrant, as it may be called simultaneously from different threads.

Co-authored-by: Florian Reimold <11774314+FlorianReimold@users.noreply.github.com>
Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

ecal/core/src/io/snd_sample.cpp

@@ -45,6 +45,7 @@ namespace eCAL
   {
     if (!m_udp_sender) return(0);
 
+    std::lock_guard<std::mutex> const send_lock(m_payload_mutex);
     // return value
     size_t sent_sum(0);
 

ecal/core/src/io/snd_sample.h

@@ -24,6 +24,7 @@
 #pragma once
 
 #include <memory>
+#include <mutex>
 
 #include "udp_sender.h"
 
@@ -47,6 +48,7 @@ namespace eCAL
     SSenderAttr                       m_attr;
 
     std::shared_ptr<eCAL::CUDPSender> m_udp_sender;
+    std::mutex                        m_payload_mutex;
     std::vector<char>                 m_payload;
   };
 }