QReadLocker / QWriteLocker instead manual lock() unlock() for safety (e.g. exception before unlock())

master ahead manual fix

src/private/pack_p.cpp

@@ -9,6 +9,9 @@
 
 #include <limits>
 
+#include <QReadLocker>
+#include <QWriteLocker>
+
 QHash<QMetaType::Type, MsgPackPrivate::packer_t> MsgPackPrivate::user_packers;
 bool MsgPackPrivate::compatibilityMode = false;
 QReadWriteLock MsgPackPrivate::packers_lock;
@@ -41,9 +44,9 @@ quint8 *MsgPackPrivate::pack(const QVariant &v, quint8 *p, bool wr)
     else {
         if (t == QMetaType::User)
             t = (QMetaType::Type)v.userType();
-        packers_lock.lockForRead();
+        QReadLocker locker(&packers_lock);
         bool has_packer = user_packers.contains(t);
-        packers_lock.unlock();
+        locker.unlock();
         if (has_packer)
             p = pack_user(v, p, wr);
         else
@@ -281,17 +284,15 @@ bool MsgPackPrivate::register_packer(QMetaType::Type q_type, qint8 msgpack_type,
         qWarning() << "MsgPack::packer for qtype" << q_type << "is invalid";
         return false;
     }
-    packers_lock.lockForWrite();
+    QWriteLocker locker(&packers_lock);
     if (user_packers.contains(q_type)) {
         qWarning() << "MsgPack::packer for qtype" << q_type << "already exist";
-        packers_lock.unlock();
         return false;
     }
     packer_t p;
     p.packer = packer;
     p.type = msgpack_type;
     user_packers.insert(q_type, p);
-    packers_lock.unlock();
     return true;
 }
 
@@ -300,9 +301,9 @@ quint8 *MsgPackPrivate::pack_user(const QVariant &v, quint8 *p, bool wr)
     QMetaType::Type t = (QMetaType::Type)v.type() == QMetaType::User ?
                 (QMetaType::Type)v.userType() : (QMetaType::Type)v.type();
     QByteArray data;
-    packers_lock.lockForRead();
+    QReadLocker locker(&packers_lock);
     packer_t pt = user_packers[t];
-    packers_lock.unlock();
+    locker.unlock();
     quint32 len = pt.packer(v, data, wr);
     if (len == 1) {
         if (wr) *p = 0xd4;