example for logger class + minor improvements

examples/c++/logger.cxx

@@ -1,16 +1,34 @@
+#include <thread>
+#include <vector>
+
 #include "upm_logger.hpp"
 
 using namespace upm;
 
+void print()
+{
+  UPM_LOG(LOG_DEBUG) << "Thread " << std::this_thread::get_id() << ": running loop with 3 iterations";
+
+  for (int i = 0; i < 4; ++i) {
+    UPM_LOG(LOG_DEBUG) << std::this_thread::get_id() << ": i = " << i;
+  }
+}
+
 int main()
 {
+  std::vector<std::thread> threads;
 
   UPM_LOGGER::LogLevel() = LOG_INFO;
 
-  UPM_LOG(LOG_WARNING) << "a loop with 4 iterations";
+  UPM_LOG(LOG_WARNING) << "Testing the upm logger";
 
-  for (int i = 0; i < 4; ++i) {
-    UPM_LOG(LOG_DEBUG) << "i = " << i;
+  // Launching 5 threads
+  for (int i = 0; i < 5; ++i) {
+    threads.push_back(std::thread(print));
+  }
+
+  for (auto& thread : threads) {
+    thread.join();
   }
 
   return 0;