Improved logging

It should better indicate when and why it stops running.
Also added log about finishing processing saved data when no writer thread is used.

auditd-plugin-clickhouse.cpp

@@ -58,6 +58,7 @@
 
 int runpipes[2] = { -1, -1 };
 volatile bool running = true;
+volatile bool got_signal = false;
 int write_thread_control_pipes[2] = { -1, -1 };
 int write_thread_data_pipes[2] = { -1, -1 };
 
@@ -108,6 +109,8 @@ static void stop_running()
 
 static void term_handler(int sig)
 {
+	got_signal = true;
+
 	stop_running();
 }
 
@@ -659,6 +662,8 @@ int main(int argc, char **argv)
 
 	try
 	{
+		Logger::write("Initializing");
+
 		clickhouse::ClientOptions client_options;
 
 		std::string table_name = "AuditData";
@@ -965,8 +970,12 @@ int main(int argc, char **argv)
 					}
 				}
 			}
+
+			Logger::write("Wrote all saved data to DB");
 		}
 
+		Logger::write("Initializing data processing");
+
 		std::unique_ptr<std::thread, void(*)(std::thread*)> writer_thread(
 				use_writer_thread ? new std::thread(
 					writer_thread_function,
@@ -1015,6 +1024,8 @@ int main(int argc, char **argv)
 		pollfds[0].fd = STDIN_FILENO;
 		pollfds[1].fd = runpipes[0];
 
+		Logger::write("Initialization finished");
+
 		while (running)
 		{
 			pollfds[0].events = POLLIN | POLLHUP;
@@ -1057,9 +1068,12 @@ int main(int argc, char **argv)
 			else if ((pollfds[0].revents & POLLHUP) || (pollfds[0].revents & POLLERR))
 			{
 				// stdin closed, no more data, finish running
+				Logger::write("Stdin hangup or error, stopping");
 				running = false;
 			}
 		}
+
+		Logger::write("Finishing running, signal received: %s", got_signal ? "true" : "false");
 	}
 	catch (const std::exception &e)
 	{
@@ -1072,5 +1086,14 @@ int main(int argc, char **argv)
 		return -1;
 	}
 
+	try
+	{
+		Logger::write("Finished running");
+	}
+	catch (...)
+	{
+		// ignore exceptions here
+	}
+
 	return 0;
 }