Posts Tagged developer

Fast PHP array_unique for removing duplicates

PHP’s native dedupe function, array_unique, can be slow for large amount of input. Here I’m going to talk about a simple function that performs the same task but which runs a lot faster.

Often, people spout PHP optimisation advice that is incredibly misguided, so I want to make it clear up-front that you should be benchmarking your scripts using xdebug before you start optimising, and very often the real bottlenecks cannot be avoided by using “micro-optimization”. Here’s a nice PDF on Common Optimization Mistakes.

Now I’ve got that disclaimer out of the way, I believe it’s OK to talk about making a faster array_unique because it’s often used on large amounts of data – for example removing duplicate email addresses, and as such there are genuine use cases for a fast array_unique in PHP. Also our fast_unique function can be several seconds faster than array_unique so we’re not necessarily talking about micro-optimisation here; on 200k duplicate entries, array_unique takes nearly 5 seconds on my windows dev box, fast_unique takes <1 second on the same data. On 2 million entires the results are staggering – performance graphs are given below (but then, why are you doing that kind of work in PHP?).

The function looks like this:
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Caching in Javascript with Cachejs

Here’s a useful open-source (MIT license) javascript caching object I developed for my job at GG.com, the best horse racing site on the net.
(I am contractually obliged to say that every time I mention the URL. Not really though).

Like most web applications these days, we make fairly extensive use of Ajax, sending and receiving JSON data across the net on hover events and so on.

However, we’ve found that all those HTTP requests can slow down the user experience, and causes unnecessary extra load on our application servers, so we decided to employ a client-side Least Recently Used (LRU) caching object, so that we can reduce the number of HTTP requests, and increase the response speed for cachable queries. It employs lazy garbage collection, just like memcached does. In fact we see this as a kind of “memcache for javascript”, if that makes any sense at all.

It depends upon no external libraries. Here’s a simple usage example:

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CSS Gradient Background – Cross Browser!

You read that right. This works in:

  • Firefox >=3.6
  • MSIE >=5.5 (!)
  • Safari >=4
  • Chrome

Oh Em Gee, I’ve got a CSS-applied Gradient.

How neat is this?

I mean really, this is super cool.

And it degrades gracefully in older browsers and Opera.

My boss Mike passed this little CSS gem to me, and now dear reader I pass it to you. It was orignally developed by FakeDarren, who posted a great little CSS button example. I find it useful for those times when designers get all fancy with gradiented backgrounds.

I’ve condensed Darren’s CSS down to these four lines plus comments, which will give you the lovely Green-to-Black CSS gradient background you can see above.

  .gradientV{
/* thanks to http://blog.fakedarren.com/2010/01/cross-browser-css-gradients/ */
/* and http://www.puremango.co.uk/2010/04/css-gradient/ */
    /* fallback (Opera) */
    background: #008800;
    /* Mozilla: */
    background: -moz-linear-gradient(top, #00FF00, #000000);
    /* Chrome, Safari:*/
    background: -webkit-gradient(linear,
                left top, left bottom, from(#00FF00), to(#000000));
    /* MSIE */
    filter: progid:DXImageTransform.Microsoft.Gradient(
                StartColorStr='#00FF00', EndColorStr='#000000', GradientType=0);
  }

And as you may have guessed by the ‘V’ in the class name, you can also do horizontal gradients – here are some more examples for left-right gradients, and we see what happens when we apply animations to a gradiented DIV.
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Howard Yeend: UK Web Developer CV

Northampton UK / howard.yeend@gmail.com

Availability

Not currently seeking work. Sorry! (updated Mar 2013)

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