I am trying to write a plugin for Wireshark that will run a TCP server on a
service thread. The TCP server will receive a new frame number from another
application and then use the Plugin IF function plugin_if_goto_frame to cause
Wireshark to jump to the new frame number. I have found through various
experiments that plugin_if_goto_frame must run on the main thread. I'm writing
the plugin in Qt and C++, exposing the callbacks using extern "C" declarations.
The callbacks are being called correctly and that all looks fine.
I'm using a Qt cross-thread (QueuedConnection) signal and slot to communicate
between my service thread and the main thread. The problem I am having is that
although the service thread emits the signal (well it executes the instruction)
the slot in the main thread doesn't get called. I've removed all of the TCP
server code to simplify things. The relevant bits of the code looks like this:
syncro.h
#ifndef SYNCRO_H
#define SYNCRO_H
#include <QtCore>
#include "mythread.h"
class Syncro : public QObject
{
Q_OBJECT
public:
void Initialise(MyThread *);
public slots:
void jumpToFrame(int);
};
#endif // SYNCRO_H
syncro.cpp
#include <plugin_if.h>
#include "syncro.h"
#include <QtCore>
#include <QDebug>
void Syncro::Initialise(MyThread *serviceThread)
{
// connect(serviceThread, SIGNAL(syncroGoFrame(int)), this,
SLOT(jumpToFrame(int)), Qt::DirectConnection);
connect(serviceThread, SIGNAL(syncroGoFrame(int)), this,
SLOT(jumpToFrame(int)), Qt::QueuedConnection);
}
void Syncro::jumpToFrame(int new_frame)
{
plugin_if_goto_frame(new_frame);
return;
}
mythread.h
#ifndef MYTHREAD_H
#define MYTHREAD_H
#include <QtCore>
class MyThread : public QThread
{
Q_OBJECT
public:
MyThread();
void run();
signals:
void syncroGoFrame(int);
};
#endif // MYTHREAD_H
mythread.cpp
#include "mythread.h"
#include <QtCore>
#include <QDebug>
MyThread::MyThread()
{
}
void MyThread::run()
{
while (true)
{
qDebug() << "Running";
sleep(3);
qDebug() << "Still Running";
emit syncroGoFrame(22);
}
}
packet-syncro.cpp
static int proto_syncro = -1;
static MyThread *serviceThread;
static Syncro *mainObject;
void
proto_register_syncro(void)
{
module_t *syncro_module;
proto_syncro = proto_register_protocol("Syncro Service",
"Syncro",
"syncro");
syncro_module = prefs_register_protocol(proto_syncro,
proto_reg_handoff_syncro);
if (!serviceThread)
{
serviceThread = new MyThread;
mainObject = new Syncro;
mainObject->Initialise(serviceThread);
serviceThread->start();
}
return;
}
When I run the code the extra thread starts OK and it starts to cycle around
the loop with the 3 second sleep. However, the connected slot function
Syncro::jumpToFrame(int new_frame) does not get called. If I change the connect
from QueuedConnection to DirectConnection the slot function gets called but, as
expected, in the context of my serviceThread. I need the slot function to run
on the main thread.
I guess it is because my jumpToFrame slot function is not on the main thread
event loop, but I don't understand how to get it on the loop.
Any advice would be much appreciated.
Thanks and regards...Paul
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