Personal Musings for Public Consumption

WordPress looks nice, but is a rats nest of code under the hood.  If you configure nginx* to proxy back to Apache*, you may find yourself with a nifty pile of never ending 301 redirects.  I've solved this before, but had long since forgotten.  Below I've got my recipe for fixing.

Albeit scarred for life, I just survived an encounter with Visual Basic for Excel (VB 6.3).  I haven't had to muck around with this kind of shit in forever (getting close to a decade), but thought it'd be neat to save the day and flex a little programming foo.  Last time I did anything with VB... it was essentially contrived data munging taken from an easy to manipulate spreadsheet.  This challenge?  Reading a chunk of user entered data and populating a drop-down list box.  Not so hard, right?  Right?  Oh. My. God.

The data input required me to iterate over a non-unique list of values in a column of a spreadsheet, create a unique list, sort, and insert the result in to a combo box (drop down list, whatever your widget vernacular). Figuring this must be a well documented method or function, I searched inside of Microsoft's VB help editor for term array to get a list of helper functions. It should have been a clue that this was gunna suck when the result was nearly empty and largely irrelevant.

But, being the stubborn clod that I am with regards to being able to hammer through problems, this did not deter (hindsight? I should have run for the hills, tail tucked firmly between legs). Jumping over to $GOOG, I didn't see anything that indicated there was any kind of a unique() function or method. More surprisingly, there isn't a sort() method. Unbelievable. Wanna know what's sad? I'm not the first one to deal with this.

I dare you: type in to your search engine of choice, a search query that goes something to the extent of: "[language] array sort" or change out "sort" for "unique". Ruby, C++, Java and even PHP: all well documented and easy to search for. VB? bwhahahaha! Not so much.

After a few dozen useless search results, I started panic'ing and the reality of having to dust of a qsort() routine from some of my more anctient brain tapes was starting to seem like a less than awful idea. Fortunately, I struck gold and it turns out other people carry around little stashes of code that return a unique array... Though I've misplaced the link, my favorite blurb of VB code was an implementation of qsort(). Honestly, when was the last time you had to write/include array primitives?

Oh! And did you know that VB lacks the ability to continue an iteration in a for loop? Try writing the C equiv in VB: for (int i = 0; i < 100; ++i) continue; I would have given my left hangnail to be able to write Continue For in the VB version. Supposedly newer versions of VB have this, but that just seems like a language omission that's beyond brain-dead. Thank god for Goto labels otherwise I'd be still hacking away I fear. *facepalm*

Microsoft has made VB painful to develop in and has crippled its help functionality on Windows. In fact, it is so bad on Windows that I resorted to using the help editor on my Mac laptop, should've been a clue (the irony of having better VB help in Mac Office can't be understated). VB remains as painful of an experience as I remember, but now that I've got a boatload more experience under my belt, it stands out even more as a technical perversion.

UniqueArray() function included after the break. I don't want to have to dick around searching for that ever again. *sigh*

The more believable reason for why bugs take a long time to get fixed.

Finally, a technical post I feel worthy of commenting on.

Performance of my application changes from time(3) to gettimeofday(2). Why? -Joe Open Source Developer

Doh! Really common question and should be an FAQ at this point.... or it is, but an under-published FAQ that only the performance wonks seem to know or run into as an issue. In short, gettimeofday* == EBAD && clock_gettime* == EGOOD. I think the best discussion on this is PHK's post titled Timers and timing, was: MySQL Performance 6.0rc1. Please read. Essentially, FreeBSD*'s gettimeofday* syscall is monotonic, highly accurate and precise, and Linux's is not. Therefore, Linux's gettimeofday* syscall is faster and less accurate than FreeBSD*'s. I happen to agree that gettimeofday* should be monotonic and I take issue with Linux*'s gettimeofday* implementation. Monotonic time keeping requires CPU synchronization (which gettimeofday* does under FreeBSD* and should be done under all operating systems) and will always be slow as a result. Most applications that do not require precise time synchronization across threads and CPUs should use clock_gettime* with a clock_id of CLOCK_REALTIME_FAST. Few applications actually need highly precise, highly accurate, monotonic time measurement and instead can skid by with highly precise, accurate, but non-monotomic time keeping. And now you know.

Robert Ennals's Software Transactional Memory Should Not Be Obstruction-Free is definitely unstupid and worth reading. Same with Dave Dice, Ori Shalev, and Nir Shavit's paper on Transactional Locking II. Survey says? Holy damn. Use "per object transaction locking" models where possible and avoid the use of pthread_mutex_lock*, pthread_rwlock_rdlock*, and pthread_rwlock_wrlock* where possible. STM makes pthreads* the new fail. For some idiotic reason, I was thinking/hoping that rwlock's would suck less than they apparently do. CAS? Eh, not quite worth the hassle yet.