Terminate the engine if another instance is already running

src/shared/Communication.cpp

 #include <Windows.h>
 #include <Lmcons.h>
 #include <Sddl.h>
 
 #include "Communication.h"
 
 namespace
 {
   const int bufferSize = 1024;
 
@@ skipping 112 matching lines @@
   return Communication::InputBuffer(stream.str());
 }
 
 void Communication::Pipe::WriteMessage(Communication::OutputBuffer& message)
 {
   DWORD bytesWritten;
   std::string data = message.Get();
   if (!WriteFile(pipe, data.c_str(), data.length(), &bytesWritten, 0))
     throw std::runtime_error("Failed to write to pipe");
 }
+
+bool Communication::PipeExists(const std::wstring& name)
+{
+  return WaitNamedPipe(name.c_str(), 100) || GetLastError() == ERROR_SEM_TIMEOUT;
+}