Surgeons Net Blog

Detecting Application Idle in Qt 4

2010-08-10T17:00:00.005+01:00

The Patient Management System we are writing required a timeout for logins after a certain period had elapsed. So we needed to detect application idle. A couple of examples exist on the the web, but seemed incomplete and not thread safe. I also wanted a singleton class model so that I could have notifications of idle in any of my QObjects. So here is my implementation. Comments and improvements will be appreciated.

Header File:

#ifndef IDLETIMER_H
#define IDLETIMER_H

#include 
#include 
#include 
#include 

class IdleTimer : public QObject
{
    Q_OBJECT
public:
    // Singleton class stuff
    static IdleTimer* instance(QObject *parent=0, int seconds=0) {
        static QMutex mutex;
        if (!m_Instance) {
            mutex.lock();
            m_Instance = new IdleTimer(parent, seconds);
            mutex.unlock();
        }
        return m_Instance;
    }

    static void drop() {
        qDebug("IdleTimer dropped ...");
        static QMutex mutex;
        mutex.lock();

        m_timer->stop();
        if(m_timer) delete m_timer;

        if (m_Instance)
            delete m_Instance;
        m_Instance = 0;
        mutex.unlock();
    }

    void start(int seconds = 0);
    void stop();

private:
    explicit IdleTimer(QObject *parent, int seconds);
    explicit IdleTimer() {}
    ~IdleTimer() {}

    IdleTimer(const IdleTimer &); // hide copy constructor
    IdleTimer& operator=(const IdleTimer &); // hide assign op

    static IdleTimer *m_Instance;
    static QTimer *m_timer;

    static QMutex m_timeoutMutex;
    static int m_timeout;

signals:
    void idle();

private slots:
    void idleTimeout();

protected:
    bool eventFilter(QObject *obj, QEvent *ev);
};

#endif // IDLETIMER_H

And the implementation


/*!
 * Small class for detecting idle in the applcation
 */

#include "IdleTimer.h"

// Static initialisers
IdleTimer *IdleTimer::m_Instance = 0;
QTimer *IdleTimer::m_timer = new QTimer();
int IdleTimer::m_timeout = 0;
QMutex IdleTimer::m_timeoutMutex;

/*!
  * Class constructor
  */
IdleTimer::IdleTimer(QObject *parent, int seconds) :
        QObject(parent)
{
    m_timeoutMutex.lock();

    if (seconds)
        m_timeout = seconds;

    Q_ASSERT(parent);
    Q_ASSERT_X(m_timeout, "IdleTimer Constructor", "The timeout must be specified in the first call to instance.");

    parent->installEventFilter(this);
    m_timer->singleShot(m_timeout*1000, this, SLOT(idleTimeout()));

    m_timeoutMutex.unlock();
}

/*!
  * Either reset the timeout to a different value to restart the timer
  */
void IdleTimer::start(int seconds/*=0*/) {
    m_timeoutMutex.lock();

    if(seconds)
        m_timeout = seconds;

    Q_ASSERT_X(m_timeout, "IdleTimer reset", "A timeout must be specified either in this call or in the first call to instance.");

    m_timer->start(m_timeout*1000);

    m_timeoutMutex.unlock();
}

void IdleTimer::stop() {
    m_timeoutMutex.lock();
    m_timer->stop();
    m_timeoutMutex.unlock();
}

/*!
  * The vent filter
  */
bool IdleTimer::eventFilter(QObject *obj, QEvent *ev)
{
    if(ev->type() == QEvent::KeyPress ||
        ev->type() == QEvent::MouseMove)
        // now reset your timer, for example
        IdleTimer::m_timer->start();

    // Must return to allow further processing
    return QObject::eventFilter(obj, ev);
}

/*slot*/
void IdleTimer::idleTimeout() {
    qDebug("Application has been idle, emitting idle signal ...");
    emit idle();
}

Mounting virtualbox shares in a linux (Ubuntu) guest

2010-04-21T23:10:00.002+01:00

Mounting VirtualBox shares in a Linux guest is not as straight forward as for a Windows guest. I have only tried this on a Ubuntu guest but I see no reason why it wouldn't work in other flavours.

Some pre-requisites:

Make sure the VirtualBox guest additions have been installed. There are plenty of guides about this
When you create your shared directories DO NOT accept the default name. Use a prefix. For example HostDocuments for the host Documents folders instead of Documents.
The reason for this is if you use the default name a protocol error will be reported when you mount the shared dir. I don't know why but this small work around fixes the issue
Make sure the vboxvfs module is loaded by adding vboxvfs to the end of /etc/modules

sudo sh -c 'echo "vboxvfs" | cat >>/etc/modules'

Now we need to allow mounting of vbox shares by normal users.

sudo select-editor and make sure nano is selected. This is a much nicer editor than vi
Now edit the sudoer file using sudo visudo.

Add the line: %plugdev ALL=(ALL)NOPASSWD:/sbin/mount.vboxsf
It may be that the group plugdev is a Ubuntu only group. Choose a group that all users belong to. Or create a 'users' group and add the users to it
Create a mounting script in /usr/local/bin.

sudo nano /usr/local/bin/mountVboxShares

Paste the following code, but replace the variables at the top and add sections as appropriate.

#!/bin/bash PROJECTDIR="$HOME"/Projects PROJECTSHARE="HostProjects" DOCSDIR="$HOME"/Documents DOCSSHARE="HostDocuments" if [ ! -d "$PROJECTDIR" ]; then mkdir "$PROJECTDIR" fi /usr/bin/sudo mount.vboxsf -o uid=`id -r -u`,gid=`id -r -u` "$PROJECTSHARE" "$PROJECTDIR" if [ ! -d "$DOCSDIR" ]; then mkdir "$DOCSDIR" fi /usr/bin/sudo mount.vboxsf -o uid=`id -r -u`,gid=`id -r -u` "$DOCSSHARE" "$DOCSDIR"
Allow everyone to execute this script sudo chmod 755 /usr/local/bin/mountVboxShares
Finally add the mount script to the end of the system wide profile script sudo sh -c 'echo "/usr/local/bin/mountVboxShares" | cat >>/etc/profile'

Converting Joomla sites from 1.0 to 1.5 cheatsheet

2010-03-01T19:10:00.001Z

Some useful links for Joomla 1.5 component development:

The guys at the Art of Joomla have a really nice crib sheet for converting your 1.0 extensions to 1.5. Well done and thank you.
Using the JHTML:: functions to create lists

Ubutnu ext3 to ext4 upgrade - won't mount filesystem!

2010-02-08T15:02:00.001Z

I have just had a little heart stop moment.

I followed the Ubuntu wiki instructions on migrating from ext3 to ext4. After the tune2fs bit I rebooted as instructed and the system could not mount the new filesystem. Errors about bad superblocks and bad group descriptors, but nothing being done about them. fsck did not run correctly and I was left with an un-mountable drive, so I could even mount as ext3. Ahhhh....

Fortunately I have a live CD install of 9.10 on USB from which I could boot and run a fsck.ext4 on my partition.

So my suggestion is that before migrating from ext3 to ext4 do two things:

BACKUP all your data
Do the migration from a live CD / USB. The advantage of this is that you save on all the reboots too.

Setting up qt4 with visual studio 2005 and 2008

2009-10-07T20:30:00.002+01:00

It is not clear (or wasn't to me) how to use QT4 with Visual Studio. The key to the problem is that you need to re-compile QT4 for Visual Studio. If you are not using MingGW at all then you can do all this in the original QT directory. Otherwise copy the entire c:\qt\2009.03 directory to something like c:\qt\2009.03_vs2008

Open a VS command line prompt so that all the env vars are set up.

Run the configure script, my suggestion is:
C:\Qt\2009.03\qt>configure -no-qt3support -no-opengl -platform win32-msvc2005 -no-libtiff -no-dbus -no-phonon -no-phonon-backend -opensource -debug-and-release

Let it do it's thing

Then type nmake to build the VS libraries

Notes:
Use nmake confclean to clean the directory before running a new configure cmd

Setting up PostgresSQL on Ubuntu

2009-09-29T23:57:00.000+01:00

Most of my database use has been with MySQL to date as I have LAMP installations for websites but I was looking for a DB to use with a new desktop application of ours. It seems that Postgres may be a better option. Below are the steps I needed to get a Postgres server running on my laptop.

1) Install the packages
# sudo apt-get install postgresql postgresql-client pgadmin3

This will install the latest versions, which for ubuntu 9.04 at this time is 8.3 if an older version installs then change the references to directories below as appropriate.

2) Change the admin passwords

# sudo -u postgres psql template1
This will start up the command line admin tool and select the template1 db which seems to be where postgre stores user credentials

# ALTER USER postgres WITH PASSWORD 'new password';
and quit by typing \q

3) Change the ubuntu postgres user password. This is a conveinence step as all the conf files are created with postgres user and group. You could add or edit them as root with sudo and then make sure they are all chown to postgres:postgres

# sudo passwd -d postgres
Will delete the current postgres password (needed otherwise you are asked for it in the next step)
# sudo su postgres -c passwd
Enter a new password. For simplicity use the same password as the admin user above, but can be anything so long as you remember it

Restart the server with
# sudo /etc/init.d/postgresql-8.3 restart

You can now use the pgAdmin tool to connect to the DB

Additions to the Surgical Tutorials

2009-09-02T19:53:00.006+01:00

I have been making some additions to the Surgical Tutorials section of the website. Four topics added are:

The Airway and Ventilatory Management is part of a new ATLS notes section and hopefully the other tutorials will also provide for useful revision notes.

EWTD 48 hour opt out survey

2009-08-16T12:56:00.005+01:00

We have been running a short EWTD survey on the Surgeons Net site about the 48 hour EWTD week and opting out. If you haven't completed the survey then please contribute. But do note that ASiT and BOTA are going to be conducting a more detailed, longer survey in September.

If you are interested in the results then they are available live on line too.

Target Google AdSense even more by rating your content

2009-01-25T12:22:00.005Z

There is a nice article on AdSense published recently on DevShed. For my own note I had no idea you could direct what content you wanted Google to concentrate on for displaying relevant ads.

Put the main content inside these comment tags:

And things you want ignored inside:

Firefox 3 sesson restore

2008-11-17T22:59:00.002Z

Not sure why but firefox seemed to lose it's session restore feature for me. Maybe something to do with having tab mix plus installed prior to the 2 -> 3 upgrade.

Anyhow here is how to restore session saving.

Enter about:config in the address bar and say yes to the behave yourself warning!

Search down for "browser.sessionstore.resume_session_once" and change the setting to true.

and restart ...

That's it.

Clamav with Qmail-Scanner

2008-06-04T13:49:00.001+01:00

Probably the best article on getting clamav to work with Qmail Scanner

http://qmail.jms1.net/clamav/qmail-scanner.shtml

WEBSITES DOWN DUE TO FIRE AT SERVER HOST

2008-06-02T08:54:00.002+01:00

Unfortunately there has been an fire at the main data center where our servers are hosted and hence the websites and email are down.

The server company are expecting to starting bringing servers back online this evening, but it may be tomorrow morning before the network is fully restored.

Thank you for your patience.

Just a reminder of a great x-platform SVN client

2008-04-26T20:21:00.000+01:00

http://rapidsvn.tigris.org/

Setting up a subversion server Redhat CentOS

2008-02-21T23:48:00.002Z

First some useful reference links:

http://www.tgharold.com/techblog/labels/SubVersion.shtml
http://www.daniel-skinner.co.uk/setup-subversion-and-trac-on-centos-5/06/01/2008
http://www.subversionary.org/howto/setting-up-a-server-on-fedora-core-4

A Script to do the plesk directory permisson setup

2008-02-17T20:03:00.002Z

I have previously posted about changes to the plesk httpdocs directory to get it to work well with Joomla. This is a little bash script I knocked up to do the job. Just pass the username as param 1


#!/bin/bash

# First check that this is a valid username
grep "^${1}:" /etc/passwd > /dev/null 2>&1
if [ "$?" -ne "0" ]; then
  echo "Sorry, cannot find user ${1} in /etc/passwd or you didn't supply a username"
  echo "Usage: ${0} "

  exit 1
fi

userdir=`grep "^${1}:" /etc/passwd | cut -d: -f6`

if [ -d ${userdir} ] ; then
 echo "Changing to directory ${userdir}"
 cd ${userdir} && chown -R ${1}:psacln httpdocs && chmod -R g+w httpdocs && find httpdocs -type d -exec chmod g+s {} \; && /etc/init.d/httpd reload
fi

Monitoring all apache virtual hosts on plesk with logwatch

2008-02-16T16:00:00.009Z

The standard Plesk install has logwatch setup to just monitor the default httpd log, i.e /var/www/httpd/*

This is miss most things as the log file output of all the virtual hosts are not parsed. So I made a little bash script to create a load of new logwatch conf files to parse all my virtual host logfiles too. You will need to run this script each time a new domain is created. A know there is a Plesk way to run custom scripts on events, but I'll leave that for another day.


#!/bin/bash

##
## Script to create conf files and script links on a Plesk
## server that monitor all the apache log files 
##
## Visit blog.surgeons.org.uk for updates

## Location of the virtual hosts directories
vhost_root=/var/www/vhosts/

## Various logwatch directories
dir_services="/etc/logwatch/conf/services"
dir_logfiles="/etc/logwatch/conf/logfiles"
dir_scripts="/etc/logwatch/scripts/services"
http_script="/usr/share/logwatch/scripts/services/http"

## Now iter over each directory
for domain in $( ls -Ichroot -Idefault $vhost_root ); do
if [ -d "${vhost_root}${domain}" ]
then
 echo "Making services logwatch enteries for ${domain}"
 domain_us=`echo $domain | tr . _`
 (
 cat <<-END_OF_SERVICES_CONF        

###########################################################################
# Configuration file for $domain http filter         
# See blog.surgeons.org.uk for updates         ###########################################################################
Title = "httpd - $domain"

# Which logfile group...
LogFile = http_$domain_us
END_OF_SERVICES_CONF ) > ${dir_services}/http_${domain_us}.conf


 echo "Making logfiles logwatch entries for ${domain}"
 (
 cat <<-END_OF_LOGFILES_CONF
########################################################
#   Define log file group for http_$domain_us
#   See blog.surgeons.org.uk for updates
#######################################################
LogFile = /var/www/vhosts/$domain/statistics/logs/access_log
LogFile = /var/www/vhosts/$domain/statistics/logs/access_log.processed
LogFile = /var/www/vhosts/$domain/statistics/logs/access_ssl_log
LogFile = /var/www/vhosts/$domain/statistics/logs/access_ssl_log.processed

# If the archives are searched, here is one or more line
# (optionally containing wildcards) that tell where they are...
# If you use a "-" in naming add that as well -mgt

Archive = /var/www/vhosts/$domain/statistics/logs/access_log.processed.?.gz
Archive = /var/www/vhosts/$domain/statistics/logs/access_ssl__log.processed.?.gz         

# Expand the repeats (actually just removes them now)
*ExpandRepeats

# Keep only the lines in the proper date range...
*ApplyhttpDate
END_OF_LOGFILES_CONF ) > ${dir_logfiles}/http_${domain_us}.conf


## Make the script links
echo "Creating script link for ${domain}"
ln -s ${http_script} ${dir_scripts}/http_${domain_us}

fi

done

Suhosin PHP hardening

2008-02-15T15:57:00.001Z

A PHP hardening (security patch) worth checking out

http://www.hardened-php.net/suhosin/index.html

Disabling mod_security 2 for individual directories

2008-02-13T22:06:00.007Z

I ran into some trouble with mod_security falsely blocking my joomla administrator pages.

The old method of disabling mod_security by placing a SecFilterEngine Off SecFilterScanPOST Off in a .htaccess doesn't work anymore. This doesn't seem to be clear in the docs and I only found this info in a mod-sec mailing post.

So the rules now need to go directly into the apache conf files.

I have most sites hosted on a plesk server. In plesk you can add to the virtual host config inside a vhost.conf file found in "/var/www/vhosts/<domain.com>/conf/vhost.conf".
Create or edit this file and enter:


<location "/" >
SecRuleEngine Off
</location>

Apply the vhost changes if a new vhost file with:
/usr/local/psa/admin/bin/websrvmng -v -a

And reload the httpd server with:
service httpd restart

Better still disable specific rules with
SecRuleRemoveById _rule_id_

Instead of the sledgehammer SecRuleEngine Off

Joomla installation on Plesk server, getting permissions right

2008-02-12T16:11:00.005Z

Installing Joomla on a Plesk server has it's problems with permissions. I think this gives a nice solution. The original inspiration comes from the rackerhacker article.

The steps are:

Add the ‘apache’ user to the ‘psacln’ group by editing /etc/group

i.e. psacln:x:_hidden(dont actually change this field!)_:apache

Change the current directory permissions with:
cd /home/httpd/vhosts/[domain.com] chown -R [username]:psacln httpdocs chmod -R g+w httpdocs find httpdocs -type d -exec chmod g+s {} \;
This set the setuid bit on each of the directories

Reload the apache settings with /etc/init.d/httpd reload

If you are using proftp to upload files or the new joomla 1.5 ftp layer then change the umask for proftpd by editing ‘/etc/proftpd.conf’ to read Umask 002

Otherwise change the umask that php uses. The easiest, but I guess least elegant way is to add the line <?php umask (0002); ?> to the top of the administrator template index.php file. In Joomla 1.5 this is "administrator/templates/khepri/index.php"

Three cheers for vodafone, 3G on linux

2008-02-04T17:04:00.000Z

I have to say three cheers to vodafone. I have previously posted about not being able to use my 3G USB modem with Ubuntu. Well vodafone do offer a GUI that works under linux for connecting using their 3G USB modem.

The file can be downloaded from vodafone's open source development site
Choose the .deb package for Ubuntu and it works like a dream!! The USB modem is automatically detected and all that is needed is the connection settings for the UK. So enter username=web, password=web and apn=internet

Well done to vodafone.

Starting VM tools automatically and hiding to systray

2008-01-24T20:18:00.000Z

This is nothing to do with surgery, but rather acting as an aide memoir for me:

After installing vmware tools in a linux guest it is nice for the tool box to start automatically. The way to do this is to add vmware-toolbox to the start-up application list usually found under Program->Settings->Sessions.

The command line is:
/usr/bin/vmware-toolbox --iconify
or /usr/bin/vmware-toolbox --minimize

Note that the usage string for vmware-toolbox lists --inconify as the option which is spelt wrong and doesn't work.

Better still the application can be minimized to the system tray using a little app called alltray. Alltray is in the universe repo for gutsy ubuntu and is installed with 'sudo apt-get install alltray' or go to http://alltray.sourceforge.net/

Then modify the above to:
alltray /usr/bin/vmware-toolbox --iconify
to get vmware-toolbox auto started and minimised to the systray.

Ubuntu disappointment

2008-01-08T16:31:00.000Z

Maybe the title is a bit strong, but the day count to requiring a windows boot is only 3. I use my laptop extensively away from home and so have one of those USB 3G modem things. I happen to be with vodafone but of course none of the mobile companies support linux for their 3G cards.

There are a number of pages suggesting ways to get the modem to work using pppd as basically the USB modem is recognised as a serial modem once plugged in. But none of them seemed to work for me and it messed up my normal networking. So it's back to windows when out and about ...

My Ubuntu Experiment

2008-01-05T22:06:00.000Z

Over the years I have attempted to move from a windows based system to a linux based. I have always used linux based servers, which gave fantastic reliability and one had an uptime of over 400 days. You try keeping a windows system up for that length of time without a reboot! But, and here is the big but, linux desktops have never been as easy to use or as reliable. I think that is until now.

Ubuntu claims to bring linux to the masses. I am not shy of compiling my own kernel / drivers or apps, but on my desktop system I would like things to just work. So when I buy a new printer and plug it in I don't need to spend hours searching for a driver and then spend hours installing it. I have tried Ubuntu in the past but the latest version has an impressive hardware compatibility list. So here goes ...

I am trying Ubuntu out on my sony vaio VGN-SZ1HP laptop. It has a 80GB drive and I have upgraded to 1.5Gb RAM. I am using a 7Gb partition to install Ubuntu on to. Yeap you read that right. On my XP drive the c:\Windows folder alone takes up 9.2Gb. The install is pretty straight forward and most of my hardware is recognised straight out of the box. This includes my wireless card which manged to find my home network without trouble. Ubuntu >7.04 includes the ipw3945 wireless card driver and so auto configures for this card. Hotkeys such as brightness / volume and mute work.

The webcam requires an additional driver which at present I can't find.

It comes with openoffice installed as standard. Which is a free to use office suite from Sun Microsystems. This allows me to open all my old word / excel and powerpoint files. And having installed the NTFS drivers I can access my windows data drive partition from Ubuntu. So no problems there.

Printer was the next thing. I have a HPC6180 All-in-one. CUPS comes with the "HP PhotoSmart C6100 Foomatic/hpijs (recommended)" printer driver which works just fine with this printer. Tried printing from OpenOffice Writer and printing a full colour photo from GIMP - no problems.

Scanner from the printer required installation of Xsane and this scans just fine too.

So far so good...

At this point I thought I would play a DVD in the background whilst doing mundane tasks like securing the install and tweaking the firewall. I suppose all the good stuff had to end somewhere. Unfortunately, DVDs are scrambled and in theory only authorised persons can descramble them. This means Ubuntu can not include the drivers to decode commercial DVDs. A quick google search suggests that it is not necessarily an easy fix, so I'll leave that one for the mo.

At present I can't get hibernate to work either, so you'll hear about those when I have them figured out.

I am starting a count of the days until I have to boot up the windows partition again and I'll keep you posted ...

RCSI Dublin Research Position

2007-10-02T22:38:00.000+01:00

A position has become available at the National Surgical Training Centre, RCSI, Dublin for a research fellow. Broadly speaking, the research project is about the application of virtual reality simulation to surgical training.

This research is with a view to earning an MD degree. It would be ideal for a trainee awaiting a HST position in general surgery.

Read the full job specification.

Best Evidence

2007-09-04T19:27:00.000+01:00

The first in a series of articles describing the best evidence around for various medical treatment options.

Best Evidence at Surgeons Net