improve logging MT robustness

lib/log/GWLog.cpp

@@ -34,7 +34,11 @@ void GwLog::logDebug(int level,const char *fmt,...){
     va_start(args,fmt);
     xSemaphoreTake(locker, portMAX_DELAY);
     vsnprintf(buffer,99,fmt,args);
-    if (! writer) return;
+    buffer[99]=0;
+    if (! writer) {
+        xSemaphoreGive(locker);
+        return;
+    }
     writer->write(prefix.c_str());
     writer->write(buffer);
     writer->write("\n");
@@ -46,3 +50,13 @@ void GwLog::setWriter(GwLogWriter *writer){
     this->writer=writer;
     xSemaphoreGive(locker);
 }
+
+void GwLog::flush(){
+    xSemaphoreTake(locker, portMAX_DELAY);
+    if (! this->writer) {
+        xSemaphoreGive(locker);
+        return;
+    }
+    this->writer->flush();
+    xSemaphoreGive(locker);
+}

lib/log/GwLog.h

@@ -6,6 +6,7 @@ class GwLogWriter{
     public:
         virtual ~GwLogWriter(){}
         virtual void write(const char *data)=0;
+        virtual void flush(){};
 };
 class GwLog{
     private:
@@ -25,6 +26,7 @@ class GwLog{
         void logString(const char *fmt,...);
         void logDebug(int level, const char *fmt,...);
         int isActive(int level){return level <= logLevel;};
+        void flush();
 };
 #define LOG_DEBUG(level,...){ if (logger != NULL && logger->isActive(level)) logger->logDebug(level,__VA_ARGS__);}