Archive for the ‘Tech’ Category

Best GCC warning flags for compiling C++

Friday, July 18th, 2014

A recent discussion on ACCU-general gave people an opportunity to share the warning flags they like to use with g++.

I thought I’d write down the consensus as I understood it, mainly for my own reference:

-Wredundant-decls
-Wcast-align
-Wmissing-declarations
-Wmissing-include-dirs
-Wswitch-enum
-Wswitch-default
-Wextra
-Wall
-Werror
-Winvalid-pch
-Wredundant-decls
-Wmissing-prototypes
-Wformat=2
-Wmissing-format-attribute
-Wformat-nonliteral

We were advised by Jonathan Wakely that -Weffc++ is not very useful since it is mostly based on the first edition of the book Effective C++, many of whose recommendations were improved in the second edition, and also apparently GCC doesn’t do a great job of warning about them.

What git server should I use?

Tuesday, July 15th, 2014

At work we are considering whether we can use Git for our source control. I am a big fan of Git, so I’d like to see this happen.

We only need to work against a central repository most of the time, so I’m looking at what servers might work for us.

Update: This StackExchange question may help: Self-hosted replacement for Github.

Update: Added software from the StackExchange answers to the list.

Features we will need:

  • User management
  • Repository management
  • Browsing code and diffs via the web
  • Hosted in-house

Features we might want:

  • External user authentication e.g. via LDAP
  • Code review
  • Integrating with an issue tracker

Most of my use of Git so far has been against large servers like GitHub (which I really like) and SourceForge, but recently I set up a test Git server using gitolite and gitweb, which gives me my 4 “needs” above but not my 3 “wants”. It also requires command-line use of git to administer and SSH keys from users, so might not suit our system administrators or all our developers.

So, lazyweb, what server should I recommend?

Here is my research so far:

Free git server software

GitLab – looks a lot like GitHub, and appears to satisfy all 4 of my needs and all 3 of my wants. Might be a bit decentralised (ironically) for our usage e.g. the docs talk about using merge requests for code review whereas I’d expect we’d want a commit-gating style which is what I believe Gerrit provides.

SCM-Manager – looks very corporate. Likely it could satisfy my needs and my wants.

Gerrit + Gitblit – lots of code review features, used by major projects including the Android open source project. Weird that Gerrit doesn’t include a code browser and you have to add something like Gitblit. I think this will give me all 4 of my needs and all 3 of my wants.

Gitolite + gitweb – this is what I am using at the moment, and it works well, satisfying the needs above, but not the wants. Gitolite configuration is done by editing config files and pushing them into a special git repository on the server. Adding users means adding a user’s SSH key to the config repository, so requires tech-savvy users and admins. gitweb is fast and clear. My only complaint is that you don’t seem to be able to control the amount of context you see in a diff (often I want to see the full files).

Gitorious – the software behind a mature public site that some people really like. Doesn’t appear to do LDAP authentication, and may not integrate with issue tracking.

tuleap – project planning, chat, issue tracking, builds, document management, discussion board, news all in one product. Includes Gerrit for code reviews, Jenkins for build management. Supports LDAP and OpenID authentication.

Phabricator – code hosting and review, issue tracking, wiki, alerts, message boards, blogs, Q&A, polls all in one product. Supports LDAP and OAuth authentication.

GitPrep – explicitly a clone of GitHub. Seems to look nice, but a young project and not talked about much on the Internet yet.

GitBucket – explicitly a clone of GitHub. Couldn’t find much information beyond that.

GitList – only a repository viewer, but could possibly be used with gitolite instead of plain gitweb – may have more features such as full-file diffs, but I’m not sure. Looks pretty, and doesn’t have much documentation.

CGit – only a repository viewer, but definitely allows specifying the amount of context in diffs (and if you edit the URL directly you can ask for as much as you want). Very plain interface, and minimal documentation. Claims to be fast.

Cydra – may turn out to be good but no web site at the moment, so probably not mature enough to consider.

Gitosis appears to be a dead project.

Paid (in-house) git server software

Very unlikely that we will pay for anything, but here are the options I have found so far:

Atlassian Stash – one-time payment e.g. $6,000 for 100 users.

GitHub Enterprise – apparently they do in-house installations but I couldn’t find any information. GitHub has an excellent interface and features.

Microsoft Team Foundation Server – a larger system that offers Git integration as a feature.

RhodeCode – 50 users for $199/month, supports LDAP and Active Directory authentication, and code review. Claims to be highly secure.

Renewing self-signed certificate for ejabberd

Tuesday, July 15th, 2014

I run an ejabberd server on an Ubuntu 12.10 box and this week I started getting notified by my IM client that the server’s certificate had expired.

Here’s how I managed to generate a new certificate.

WARNING: this process backs up, deletes and then restores your ejabberd database, so it is probably fairly risky.

# Move any previous backups out of the way
sudo mv /var/backups/ejabberd-* ~/Desktop/

# Move the expired certificate out of the way
sudo mv /etc/ejabberd/ejabberd.pem /etc/ejabberd/ejabberd.pem.old

# Reconfigure the ejabberd package (WARNING: backs up and deletes your database!)
sudo dpkg-reconfigure ejabberd

# Make the database backup file readable
sudo chmod a+rx /var/backups/ejabberd-*/
sudo chmod a+r /var/backups/ejabberd-*/*

# Restore the backup
sudo ejabberdctl restore /var/backups/ejabberd-*/ejabberd-database

If you’re lucky, your server will now be back up with a new self-signed certificate.

In general, the policy of using dpkg-reconfigure to handle creating new self-signed certificate seems to work nicely.

What is node.js?

Monday, July 14th, 2014

Node.js is a way of writing your web applications wholly in JavaScript, which sounds like a terrible idea.

However, it is also an asynchronous programming environment that has been proven to scale really well, and it’s a collection of libraries many of which are excitingly small and well-encapsulated.

Here we just cover the basics of what it is:

Slides: What is node.js?

A mini mocking framework

Monday, July 7th, 2014

Ever wondered how a mocking framework like JMock or GoogleMock works?

We’ll look at how to write a very basic example, and find out that Java is more flexible than you may have thought.

Slides: A mini mocking framework.