Implement http persistence connection

Max simultaneous connection limit set to 500
This also release allocated memory of Connection instances at runtime instead of at program shutdown.

src/base/http/connection.cpp

@@ -29,14 +29,14 @@
  * Contact : chris@qbittorrent.org
  */
 
-#include <QTcpSocket>
-#include <QDebug>
+#include "connection.h"
+
 #include <QRegExp>
-#include "types.h"
+#include <QTcpSocket>
+
+#include "irequesthandler.h"
 #include "requestparser.h"
 #include "responsegenerator.h"
-#include "irequesthandler.h"
-#include "connection.h"
 
 using namespace Http;
 
@@ -46,27 +46,33 @@ Connection::Connection(QTcpSocket *socket, IRequestHandler *requestHandler, QObj
     , m_requestHandler(requestHandler)
 {
     m_socket->setParent(this);
+    m_idleTimer.start();
     connect(m_socket, SIGNAL(readyRead()), SLOT(read()));
-    connect(m_socket, SIGNAL(disconnected()), SLOT(deleteLater()));
 }
 
 Connection::~Connection()
 {
+    m_socket->close();
 }
 
 void Connection::read()
 {
-    m_receivedData.append(m_socket->readAll());
+    m_idleTimer.restart();
 
+    m_receivedData.append(m_socket->readAll());
     Request request;
     RequestParser::ErrorCode err = RequestParser::parse(m_receivedData, request);
+
     switch (err) {
     case RequestParser::IncompleteRequest:
         // Partial request waiting for the rest
         break;
+
     case RequestParser::BadRequest:
         sendResponse(Response(400, "Bad Request"));
+        m_receivedData.clear();
         break;
+
     case RequestParser::NoError:
         Environment env;
         env.clientAddress = m_socket->peerAddress();
@@ -74,6 +80,7 @@ void Connection::read()
         if (acceptsGzipEncoding(request.headers["accept-encoding"]))
             response.headers[HEADER_CONTENT_ENCODING] = "gzip";
         sendResponse(response);
+        m_receivedData.clear();
         break;
     }
 }
@@ -81,7 +88,16 @@ void Connection::read()
 void Connection::sendResponse(const Response &response)
 {
     m_socket->write(ResponseGenerator::generate(response));
-    m_socket->disconnectFromHost();
+}
+
+bool Connection::hasExpired(const qint64 timeout) const
+{
+    return m_idleTimer.hasExpired(timeout);
+}
+
+bool Connection::isClosed() const
+{
+    return (m_socket->state() == QAbstractSocket::UnconnectedState);
 }
 
 bool Connection::acceptsGzipEncoding(const QString &encoding)

src/base/http/connection.h

@@ -33,12 +33,12 @@
 #ifndef HTTP_CONNECTION_H
 #define HTTP_CONNECTION_H
 
+#include <QElapsedTimer>
 #include <QObject>
+
 #include "types.h"
 
-QT_BEGIN_NAMESPACE
 class QTcpSocket;
-QT_END_NAMESPACE
 
 namespace Http
 {
@@ -53,6 +53,9 @@ namespace Http
         Connection(QTcpSocket *socket, IRequestHandler *requestHandler, QObject *parent = 0);
         ~Connection();
 
+        bool hasExpired(qint64 timeout) const;
+        bool isClosed() const;
+
     private slots:
         void read();
 
@@ -63,6 +66,7 @@ namespace Http
         QTcpSocket *m_socket;
         IRequestHandler *m_requestHandler;
         QByteArray m_receivedData;
+        QElapsedTimer m_idleTimer;
     };
 }
 

src/base/http/server.cpp

@@ -30,8 +30,10 @@
 
 #include "server.h"
 
+#include <QMutableListIterator>
 #include <QNetworkProxy>
 #include <QStringList>
+#include <QTimer>
 
 #ifndef QT_NO_OPENSSL
 #include <QSslSocket>
@@ -41,6 +43,10 @@
 
 #include "connection.h"
 
+static const int KEEP_ALIVE_DURATION = 7;  // seconds
+static const int CONNECTIONS_LIMIT = 500;
+static const int CONNECTIONS_SCAN_INTERVAL = 2;  // seconds
+
 using namespace Http;
 
 Server::Server(IRequestHandler *requestHandler, QObject *parent)
@@ -54,6 +60,10 @@ Server::Server(IRequestHandler *requestHandler, QObject *parent)
 #ifndef QT_NO_OPENSSL
     QSslSocket::setDefaultCiphers(safeCipherList());
 #endif
+
+    QTimer *dropConnectionTimer = new QTimer(this);
+    connect(dropConnectionTimer, &QTimer::timeout, this, &Server::dropTimedOutConnection);
+    dropConnectionTimer->start(CONNECTIONS_SCAN_INTERVAL * 1000);
 }
 
 Server::~Server()
@@ -62,6 +72,8 @@ Server::~Server()
 
 void Server::incomingConnection(qintptr socketDescriptor)
 {
+    if (m_connections.size() >= CONNECTIONS_LIMIT) return;
+
     QTcpSocket *serverSocket;
 #ifndef QT_NO_OPENSSL
     if (m_https)
@@ -70,20 +82,34 @@ void Server::incomingConnection(qintptr socketDescriptor)
 #endif
         serverSocket = new QTcpSocket(this);
 
-    if (serverSocket->setSocketDescriptor(socketDescriptor)) {
+    if (!serverSocket->setSocketDescriptor(socketDescriptor)) {
+        delete serverSocket;
+        return;
+    }
+
 #ifndef QT_NO_OPENSSL
-        if (m_https) {
-            static_cast<QSslSocket *>(serverSocket)->setProtocol(QSsl::SecureProtocols);
-            static_cast<QSslSocket *>(serverSocket)->setPrivateKey(m_key);
-            static_cast<QSslSocket *>(serverSocket)->setLocalCertificateChain(m_certificates);
-            static_cast<QSslSocket *>(serverSocket)->setPeerVerifyMode(QSslSocket::VerifyNone);
-            static_cast<QSslSocket *>(serverSocket)->startServerEncryption();
-        }
-#endif
-        new Connection(serverSocket, m_requestHandler, this);
+    if (m_https) {
+        static_cast<QSslSocket *>(serverSocket)->setProtocol(QSsl::SecureProtocols);
+        static_cast<QSslSocket *>(serverSocket)->setPrivateKey(m_key);
+        static_cast<QSslSocket *>(serverSocket)->setLocalCertificateChain(m_certificates);
+        static_cast<QSslSocket *>(serverSocket)->setPeerVerifyMode(QSslSocket::VerifyNone);
+        static_cast<QSslSocket *>(serverSocket)->startServerEncryption();
     }
-    else {
-        serverSocket->deleteLater();
+#endif
+
+    Connection *c = new Connection(serverSocket, m_requestHandler, this);
+    m_connections.append(c);
+}
+
+void Server::dropTimedOutConnection()
+{
+    QMutableListIterator<Connection *> i(m_connections);
+    while (i.hasNext()) {
+        auto connection = i.next();
+        if (connection->isClosed() || connection->hasExpired(KEEP_ALIVE_DURATION)) {
+            delete connection;
+            i.remove();
+        }
     }
 }
 

src/base/http/server.h

@@ -60,10 +60,14 @@ namespace Http
         void disableHttps();
 #endif
 
+    private slots:
+        void dropTimedOutConnection();
+
     private:
         void incomingConnection(qintptr socketDescriptor);
 
         IRequestHandler *m_requestHandler;
+        QList<Connection *> m_connections;  // for tracking persistence connections
 
 #ifndef QT_NO_OPENSSL
         QList<QSslCipher> safeCipherList() const;