Hi,

I need some help to use pthreads in C++:

this is the code in mizio.cpp:

void Mizio::Check()
{
Mizio_View->Button_Check->setEnabled ( false );
pthread_t Mizio_Server_Thread;
pthread_create( &Mizio_Server_Thread, NULL, Mizio_Server, (void*)NULL );
QListViewItemIterator it( Mizio_View->mizio_listview );
while ( it.current() )
{
//do something
}

}

and this is mizio.h:

class Mizio : public KMainWindow
{
Q_OBJECT
public:
Mizio();
KAboutApplication *aboutMizio;
virtual ~Mizio();
void* Mizio_Server( void* );
void* Mizio_Client( void* socket );

protected:
class Mizio_CentralWidgetBase *Mizio_View;

private slots:
void ShowAboutWindow();
void Mizio_Exit();
void Retrieve();
void Check();
void Export();
};

I got these errors from g++:

mizio.cpp: In member function `void Mizio::Check_Proxies()':
* mizio.cpp:52: no matches converting function `Mizio_Server' to type ` void*(*)(void*)'
* mizio.h:37: candidates are: void* Mizio::Mizio_Server(void*)
* mizio.cpp: In member function `void* Mizio::Mizio_Server(void*)':
* mizio.cpp:118: no matches converting function `Mizio_Client' to type ` void*(*)(void*)'
* mizio.h:38: candidates are: void* Mizio::Mizio_Client(void*)

I red somewhere I have to use some wrappers but my knowledge of C++ is not so good, could someone help me so I understand the problem ?

Thank you so much,

i had similar trouble calling a member function as a new thread.

The new thread has to be static, so you can try declaring the function as static, but i dont think that will help.

Take function out of the class, make it similar to this:

void *ReadThread(void* pParam)
{
// Stuff for your thread goes in here!
MyClass* pThis = NULL;

pThis = (MyClass *)pParam;

// pThis is now the equivalent of this (pointer to your class)

pThis->CallAnotherFunction();
}

void MyClass::CreateThreadFunction()
{
// In here we will create the thread
iResult = pthread_create(&threadid, NULL, ReadThread, this
}


Hope that helps

>The new thread has to be static, so you can try declaring the function as static, but i dont think that will help.

Thank you for your kind answer, so how did you solve your problem ? Around the web there are some libraries but I don't want to install a new library, just some hints on how to succed the compilation.

Thank you,

do as i did above, remove the function from your class and put it in above the function you are calling it from

Thank you so much ! It worked without a warning !

glad to help

Hi,

I need another small help. In one of the function that is pthreaded I need two arguments, the accepted socket descriptor and the QWidget pointer:

void Mizio::Check_()
{
Mizio_View->Button_Check->setEnabled ( false );
pthread_t Mizio_Server_Thread;
pthread_create( &Mizio_Server_Thread, NULL, Mizio_Server, this );
}

void* Mizio_Server ( void* dummy)
{
Mizio* pThis = NULL;
pThis = (Mizio *)dummy;
pthread_t Client_Thread;
int Server_Socket;
int accepted_socket;
int size;
struct sockaddr_in port_addr, accept_addr;
int set_opt = 1;
fd_set read_set;
int ready_fd;

/* set up the socket on the server port */
port_addr.sin_family = AF_INET;
port_addr.sin_addr.s_addr = htonl( INADDR_ANY );
port_addr.sin_port = htons( SERVER_PORT );

Server_Socket = socket( AF_INET, SOCK_STREAM, IPPROTO_TCP );
setsockopt( Server_Socket, SOL_SOCKET, SO_REUSEADDR, (char*)&set_opt, sizeof( set_opt ) );
if ( bind(Server_Socket, (struct sockaddr*)&port_addr, sizeof( port_addr )) > 0 )
{
while(1)
{
listen( Server_Socket, 5 ); // wait for the client to try to connect
FD_ZERO( &read_set );
FD_SET( Server_Socket, &read_set );

do {
ready_fd = select( Server_Socket+1, &read_set, NULL, NULL, NULL );
}
while ( ready_fd <= 0 || !FD_ISSET( Server_Socket, &read_set ) );

// a client has connected. Accept their connection and create a thread to serve the client
size = sizeof( accept_addr );
accepted_socket = accept( Server_Socket, (struct sockaddr*)&accept_addr, &size );
pthread_create( &Client_Thread, NULL, Mizio_Client, (void*)accepted_socket );
}
}

else
{
KMessageBox::error( pThis->Mizio_View, "Can't open port 80, maybe another program is using it or you are not root !");
pthread_exit( 0 );
}

}

//So now I have to create a thread for each connected client. I need the same arguments in the Mizio_Server function plus the argument accepted_socket:

void* Mizio_Client ( void* socket )
{
char buffer[255];

while ( read( (int)socket, buffer,255 ) > 0)
{
printf ("%s",buffer);
}
close( (int)socket );
pthread_exit( NULL );
}

#include "mizio.moc"

How to have the QWidget (passed with 'this' in Mizio_Server) in this function ?
I red that I can use struct but the compiler keeps giving me syntax error when
I try to use struct_name.mizio_QWidget_pointer_name

Any idea ?? What if I send you the whole package .tar.gz by email ?
You will need QT, XFree and KDE headers to compile it.

Thank you,

you have to create a parameter struct and pass it through.

struct tagParam
{
int Param1;
int Param2;
int Param3;
}tParam, *pParam;

then just pass tParam / pParam through to createthread

Ehm, which one shall I pass to the create thread function ? tParam or pParam ?
Sorry to bother you.

tparam is an actual object, pparam is a pointer.

so if you require a pointer, use the pointer, if you require the actual object, use the object.

with create thread i think you need the pointer.


or,

you can just send through the address of the object, eg:
&tParam

thats the same as

pParam

Thank you very much Skute, I appreciate your kindness

no worries

void* Mizio_Server ( void* dummy)
{
Mizio* pThis = NULL;
pThis = (Mizio *)dummy;
struct Mizio_structure
{
QWidget *pThis;
int accepted_socket;
} *str_Pointer;

.......

114: str_Pointer.accepted_socket = accept( Server_Socket, (struct sockaddr*)&accept_addr, &size );
115: pthread_create( &Client_Thread, NULL, Mizio_Client, (void*)str_Pointer.accepted_socket );

but when compiling:

mizio.cpp:114: request for member `accepted_socket' in `str_Pointer', which is of non-aggregate type `Mizio_Server(void*)::Mizio_structure*'

and:

mizio.cpp:115: request for member `accepted_socket' in `str_Pointer', which is of non-aggregate type `Mizio_Server(void*)::Mizio_structure*'

Where was I wrong ?

void*)str_Pointer.accepted_socket

you are sending just the socket over, surely you want to send the whole object over?

You are right, I have to send the whole structure but I have to fill the variable accepted_socket first right ? So I can use it later, but why do I get the error message ? Also do you know a link or a book that explains those arabic error messages the compiler outputs ?

Thank you,