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Posts tagged with 'programming'

Revamping Frege logo

kinow @ Aug 16, 2016 23:54:03

For a while I had been wanting to try adding a flat colour to the Frege logo. This weekend had some bit of spare time, and here is the result.

Submitted to the project as pull request #299.

Current logo.

Frege current logo

And the updated logo.

Frege updated logo

The colour used was Flamingo (#EF4836), found in Flat UI Color Picker.

Perhaps not exactly revamping, since all I did was just change a colour. There were adjustments to the bézier curves as well, to better align them, but I updated both logos, not just the new one :-)

Reading notes about DRMAA v2

kinow @ Jul 20, 2016 19:59:03

The DRMAA v2 specification draft is ready to be published, and is in public comment until 31st July this year. I used DRMAA v1 to integrate Jenkins and PBS some time ago, but it was not a very elegant solution.

And in the end integrating other grid computing implementations like SGE would not be very simple.

This post contains my reading notes for DRMAA v2, and a short analysis of how this new specification could be used in a new tentative to integrate Jenkins and several grid computing implementations in a single plug-in.

( Read more ... )

Replacing a HashSet with a BitSet

kinow @ Oct 20, 2012 19:51:39

I always read the messages in the Apache dev mailing lists, including Apache Commons dev mailing list. And you should too. There are always interesting discussions. Sometimes you participate, other times you only watch what’s happening, but in the end you always learn something new.

A few days ago, I found an issue where it was being proposed to replace an unnecessary HashSet in ArrayUtils#removeElements() by a BitSet. Here’s how the code looked like:

HashSet<Integer> toRemove = new HashSet<Integer>();
for (Map.Entry<Character, MutableInt> e : occurrences.entrySet()) {
    Character v = e.getKey();
    int found = 0;
    for (int i = 0, ct = e.getValue().intValue(); i < ct; i++) {
        found = indexOf(array, v.charValue(), found);
        if (found < 0) {
            break;
        }
        toRemove.add(found++);
    }
}
return (char[]) removeAll((Object)array, extractIndices(toRemove));

The HashSet created at line 1, in the code above, was used to store the array index of the elements that should be removed. And at line 13 there is a call to removeAll method, passing the indexes to be removed. And here’s how the new code looks like:

BitSet toRemove = new BitSet();
for (Map.Entry<Character, MutableInt> e : occurrences.entrySet()) {
    Character v = e.getKey();
    int found = 0;
    for (int i = 0, ct = e.getValue().intValue(); i < ct; i++) {
        found = indexOf(array, v.charValue(), found);
        if (found < 0) {
            break;
        }
        toRemove.set(found++);
    }
}
return (char[]) removeAll(array, toRemove);

The first difference is at line 1. Instead of a HashSet, it is now using a BitSet. And at line 10, instead of adding a new element to the HashSet, now it “sets” a bit in the set (the bit at the specified position is now true). But there are important changes at line 13. The method removeAll was changed, and now the array doesn’t require a cast anymore. And the it is not necessary to cast the elements from HashSet anymore, as now the bit in the index position of the set is set to true. So the extractIndices method could be removed.

The code got simpler. But that’s not all. At Apache Software Foundation you can find a lot of talented developers - that’s why I got so excited after joining them. Besides simplifying the code, the developer responsible for these changes (sebb) also pointed out that the new code consumes less memory and is faster. Ah! And he also wrote unit tests