not able to start qlocalserver

Question

I use Qlocalsocket in my IPC solution and I am able to start the server and accept connections from QLocalSocket clients and communicate well, no prob in that.

but my problem happens when I kill the process of the server , I can't make QLocalServer listen on the same place again, I must change the service name to be able to start it again, which could not be possible at runtime environment.

so how to make the previous process to release that name?

here is how I start the server:

m_server = new QLocalServer(this);
if (!m_server->listen("serviceUniqueName")) {
    qDebug() << "Not able to start the Server";
    return;
}

score 20 · Answer 1 · edited Feb 26 '15 at 18:38

As Amartel pointed out, if the server dies, you need to delete the socket file. The best way to do is to call bool QLocalServer::removeServer ( const QString & name ):

m_server = new QLocalServer(this);
QString serverName("serviceUniqueName");
QLocalServer::removeServer(serverName);
if (!m_server->listen(serverName)) {
    qDebug() << "Not able to start the Server";
    return;
}

This way your call to listen will never fail.

score 7 · Accepted Answer · answered Mar 26 '13 at 11:37

7

Qt help:

On Unix if the server crashes without closing listen will fail with AddressInUseError. To create a new server the file should be removed. On Windows two local servers can listen to the same pipe at the same time, but any connections will go to one of the server.

So, if you are using *nix, you should remove file "/tmp/socket_name".

answered Mar 26 '13 at 11:37

Amartel

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but I have another problem now, if I try to start the server while there is another instance running it just go to "/tmp/socket_name", delete the file and starts again ... so will it direct the messages to the last one started or the first or undetermined ?? @amartel – Dorgham Mar 26 '13 at 13:03
I realy don't know, but to avoid that you can use QtSingleApplication: http://qt.digia.com/Product/Qt-Add-Ons/Qt-Solutions-Archive/ – Amartel Mar 26 '13 at 13:13
This answer is not Cross Platform since on Unix (Not Linux) the files are located under `/var/folders/` with system generated names. @Alexey proposes the use of `QLocalServer::removeServer` which is the right way to delete the file. – Itay Grudev Feb 26 '15 at 18:36

not able to start qlocalserver

2 Answers2