Avoid unnecessary memory allocation/relocation

src/base/http/connection.cpp

@@ -46,6 +46,10 @@ Connection::Connection(QTcpSocket *socket, IRequestHandler *requestHandler, QObj
 {
     m_socket->setParent(this);
 
+    // reserve common size for requests, don't use the max allowed size which is too big for
+    // memory constrained platforms
+    m_receivedData.reserve(1024 * 1024);
+
     // reset timer when there are activity
     m_idleTimer.start();
     connect(m_socket, &QIODevice::readyRead, this, [this]()
@@ -66,7 +70,18 @@ Connection::~Connection()
 
 void Connection::read()
 {
-    m_receivedData.append(m_socket->readAll());
+    // reuse existing buffer and avoid unnecessary memory allocation/relocation
+    const qsizetype previousSize = m_receivedData.size();
+    const qint64 bytesAvailable = m_socket->bytesAvailable();
+    m_receivedData.resize(previousSize + bytesAvailable);
+    const qint64 bytesRead = m_socket->read((m_receivedData.data() + previousSize), bytesAvailable);
+    if (Q_UNLIKELY(bytesRead < 0))
+    {
+        m_socket->close();
+        return;
+    }
+    if (Q_UNLIKELY(bytesRead < bytesAvailable))
+        m_receivedData.chop(bytesAvailable - bytesRead);
 
     while (!m_receivedData.isEmpty())
     {
@@ -116,7 +131,7 @@ void Connection::read()
                 resp.headers[HEADER_CONNECTION] = u"keep-alive"_s;
 
                 sendResponse(resp);
-                m_receivedData = m_receivedData.mid(result.frameSize);
+                m_receivedData.remove(0, result.frameSize);
             }
             break;
 

src/base/net/smtp.cpp

@@ -191,7 +191,7 @@ void Smtp::readyRead()
         const int pos = m_buffer.indexOf("\r\n");
         if (pos < 0) return; // Loop exit condition
         const QByteArray line = m_buffer.left(pos);
-        m_buffer = m_buffer.mid(pos + 2);
+        m_buffer.remove(0, (pos + 2));
         qDebug() << "Response line:" << line;
         // Extract response code
         const QByteArray code = line.left(3);

src/base/path.cpp

@@ -318,7 +318,7 @@ void Path::stripRootFolder(PathList &filePaths)
         return;
 
     for (Path &filePath : filePaths)
-        filePath.m_pathStr = filePath.m_pathStr.mid(commonRootFolder.m_pathStr.size() + 1);
+        filePath.m_pathStr.remove(0, (commonRootFolder.m_pathStr.size() + 1));
 }
 
 void Path::addRootFolder(PathList &filePaths, const Path &rootFolder)