Keep log files open

Author: hluk

src/common/log.cpp

@@ -65,16 +65,25 @@ void rotateLogFiles()
 
 bool writeLogFile(const QByteArray &message)
 {
-    QFile f( ::logFileName() );
-    if ( !f.open(QIODevice::Append) )
-        return false;
+    static QFile f;
+    const auto fileName = ::logFileName();
+    const bool isOpen = f.isOpen();
+    if ( f.fileName() != fileName || !isOpen ) {
+        if (isOpen)
+            f.close();
+        f.setFileName(fileName);
+        if ( !f.open(QIODevice::Append) )
+            return false;
+    }
 
     if ( f.write(message) <= 0 )
         return false;
 
-    f.close();
-    if ( f.size() > logFileSize )
+    f.flush();
+    if ( f.size() > logFileSize ) {
+        f.close();
         rotateLogFiles();
+    }
 
     return true;
 }
@@ -134,10 +143,12 @@ void logAlways(const QByteArray &msgText, const LogLevel level)
 
     // Log to file and if needed to stderr.
     if ( !writtenToLogFile || level <= LogWarning || hasLogLevel(LogDebug) ) {
-        QFile ferr;
-        ferr.open(stderr, QIODevice::WriteOnly);
+        static QFile ferr;
+        if (!ferr.isOpen())
+            ferr.open(stderr, QIODevice::WriteOnly);
         const auto simpleMsg = createSimpleLogMessage(msgText, level);
         ferr.write(simpleMsg);
+        ferr.flush();
     }
 }
 
@@ -231,7 +242,11 @@ bool dropLogsToFileCountAndSize(int maxFileCount, int keepMaxSize)
         const auto begin = logFiles.cbegin() + maxFileCount;
         for (auto it = begin; it != logFiles.cend(); ++it)
             success = removeLogFile(*it) && success;
+#if QT_VERSION >= QT_VERSION_CHECK(6,0,0)
         logFiles.erase(begin);
+#else
+        logFiles.erase(logFiles.begin() + maxFileCount;);
+#endif
     }
 
     if (keepMaxSize < 0)