Monumental App Update Mess Up!

A few weeks back I received a request to add in the ability to select half days in the Retirement Countdown Clock app (http://blog.v-s-f.co.uk/2016/02/retirement-countdown-clock-app/) and I decided that this was a quick change that wouldn’t take too long, so why not πŸ™‚

Well I made a complete mess up of the update… It started off as seeming like a simple update, but I’d just had a rather large problem on my laptop that killed the SSD, so had not much software installed on the new hard drive. After all the necessary apps were installed, I set about updating the app, adding in the ability to select the half days. It only took about 4 hours in total to make the code changes and test (most of which was updating the runtime target version). I packaged it, tested it on my laptop and old phone, both of which said they would install from fresh and then added a new submission to the store.

Job done πŸ™‚ or so I thought…

Two days after the app was published to the store, I logged in and to my horror I’d received over 11,000 crash reports!!! O.M.G!

All the crash reports were for the new version (2.1.0.0) and all were in exactly the same line of code… I wondered well how come it worked on my laptop and phone then? And the key answer was that it installed the app from fresh and didn’t do an update. I dashed around the house to find anoher phone I hadn’t tested on and updated the app from the store. Lo and behold, it crashed as soon as you tried to open the app from the start screen πŸ™

I had all the info I needed in the crash reports to find the particular dodgy line of code – wasn’t handling the previously stored int and converting correctly into a decimal. Less than two hours later, a new submission was sent for approval to the store, but it takes a minimum of a day to get a submission approved… In that time the crash reports topped 20,000.

I learnt a very valuable lesson – don’t rush a change through, even if it seems simple and make sure you test it as if you’ve done an upgrade as well as a fresh install!

Sorry to all those people that downloaded the dodgy update, hopefully you’ve updated to 2.1.1.0 and it’s now working again.

Outlook for Android – Can’t use it for Gmail account!

I used to have a Microsoft Lumia 550 phone, which although basic just worked and really well. Unfortunately I’m a little clumsey and managed to drop it around a dozen times when getting out of the car at work (yeah, you’d think I’d learn). It managed to survive those drops, but only just and ended up with a lovely set of cracks across the screen which I superglued to stop them completely distroying the screen and to prevent getting glass shards in my fingers.

Anyway, it’s got to the point where I needed to get a replacement phone and I would have gone for another Windows phone, but there haven’t been any new releases for a while and I refuse to pay Β£600+ for the HP one. So, I’ve reluctantly bought an Android…

Why reluctantly? Well I believe Google is getting a little scary in it’s acquisitions (Boston Dynamics) and the recent purchases of a couple of certificate authorities concerns me about personal privacy.

Anyway, I’ve set up my phone to remove a lot of the Android pre-installed crap from Google and set my default browser to Firefox. I thought nothing of doing this until just last week when Outlook refused to connect to my Gmail account and prompting to re-authenticate. I’d click ok, re-authenticate and get a 403 error from Google. After a couple of tries, I remove my Gmail account and tried to re-add it.

Much to my suprise, I can’t re-add my account unless I set Chrome as my default browser!!! Talk about anti-competitive behaviour from Google!

I absolutely refuse to use Chrome as my default Android browser just so that I can use my Gmail account from Outlook!

Home Monitoring Upgrade (Part 2) – HSQLDB to MySQL

As mentioned in my previous post (see http://blog.v-s-f.co.uk/2017/04/home-monitoring-upgrade/), the first task I have is to migrate from HSQLDB to MySQL.

Because the system logs data every minute while I have power in the house and I want to minimise downtime when I actually have a fully working upgrade, I’ve experimented with a copy of the live HSQL database.

Once I’d copied it from my server to my laptop I then attempted to view the data in notepad++ – yeah, not a particularly smart move! NP++ cannot handle files over about 100M. It also turns out (having more’d the .data file) that the data is not in a readable state. I had a performance issue with a select query a long time back and changed the table to cached.

So, luckily at work a colleague had introduced us all to a great database tool called SQL Workbench. It can work with most databases and unlike SQuirreL, it doesn’t crash when looking at the work DB2 database.

Using SQL Workbench, I’ve then created a script file which creates the new consolidated table and loads data from the old tables in to the new + drops the old tables. The end result is a 122,398KB HSQLDB script file which is human readable.

Next step was to get MySQL running on my server. Instead of installing it directly though, there’s a Docker image available.

My first few attempts at inserting the data from the HSQLDB file in to the MySQL database were less than impressive! One of the attempts had the server running flat out (100% cpu) for over an hour when I finally decided that it was probably not going to complete the import this year and nuked it!

So having learnt a few lessons about not using single row inserts(!), but batching them in to multi-row inserts of 100,000 and a few MySQL deafult parameter increases (although I’m not sure if these are necessary as the batch inserts seemed to make most difference), I was finally able to import the data. It still took a few minutes from running the MySQL container to it being available – but that’s significantly better than running for hours importing the data!!

Now that I have the necessary scripts and knowledge to migrate the data, the next part is re-writing the application that receives the Arduino data, uploads to PVOutput and serves the hot water display Arduino.