Solipsism Gradient

I just published the Xcode project for the AddLicense tool I mentioned previously. Enjoy.

Posted by 0xced:

Rainer Brockerhoff wrote:

If there’s interest, I may clean up and publish the source sometime, though it uses all sort of gronky old APIs (Resource Manager etc.).

Oh yes, there is interest!

We’ve just arrived at Wangfujing Grand Hotel in Beijing, China. Tired but all went very well; we’re off to get some tourism done, more later.

Update: the CocoaHeads Beijing talk went quite well.

So, I’m typing this from the VIP lounge at the GRU (Guarulhos/São Paulo) airport. In a few hours we’ll fly to Frankfurt over Paris, and a few days later, Beijing.

Must get busy preparing my talk for Cocoaheads Beijing, was too busy to do anything before our departure. More as it happens!

Non-development developments, that is.

We’ve been busy packing for our upcoming trip to China and other Asian countries. Also, moving from our current apartment to a new one – more packing! I also just sold my desktop iMac (more packing, erh, backing-up); by the time we get back in mid-November there should be a new generation of iMacs out. Meanwhile, essentials are being copied to my MacBook Air, and I’ll work based from that for the next two months.

You can tell that I decided to schedule all traumatic experiences at once! Better to get them done and over with…

Anyway, we go off the coming weekend. On the way to Beijing there’ll be a stopover of a few days in Frankfurt, Germany; enough to de-lag a little, and visit with family.

If all goes well, we’ll arrive in Beijing in the early afternoon of Sept. 25, and in the evening I’ll do a small presentation for the local CocoaHeads chapter. (At this time, that page shows Sept. 26 but we’re trying to move it to the 25th.) I gather that all members are rather young, and will be amazed at someone over 40 writing software!

At any rate, I plan to talk a little about my professional experience, then move to the main topic – tentatively named “Protect Your Application Against Evil Hackers (or, at least, against the lazy ones)” – and finally showing some pictures from exotic places like Brazil and California. If it comes off well, I’ll post the slides somewhere here for downloading.

After a little more than two weeks in China we’ll depart from Shanghai for a 4-week cruise, going to Japan, Hongkong, Philippines, Malaysia, Brunei, Singapore and Vietnam. On the way back to Brazil there’ll be another few days of stopover in Paris.

Posting updates here from China may not be easy, but I’ll try.

The conference will be over tomorrow and I’m quite satisfied with the outcome. Now for some comments about the announcements and (NDA permitting) about what I learned.

I had some vague idea of going to some iPhone sessions and letting presenters (or friends developing for the iPhone) convince me that I should start developing for it. No such thing happened; session overlap was so severe, and there were so many labs to go to, and people to talk to, that I skipped any non-Mac session or discussion. What little I heard in the corridors confirmed my notion that the current state of iPhone development and the AppStore deviates too far from my preferred position as a utility developer – a niche Apple still keeps closed on the iPhone. Maybe when the tablet comes out…

Speaking of tablets, while everybody agrees that one is in the works, it seems to be a year or so away from announcement. (Ditto for the new CPUs I hinted at, in my last post.)

Snow Leopard is the small new thing. Small for the user in a sense; it’s just refinements and greater speed. For developers, though, it’s the BIG new thing. And, as variously described as early as a year ago (can’t find URLs right now), much of the new stuff is driven behind the scenes by open-source projects Apple is driving: the Clang compiler, the LLVM back end, and the technologies made possible by Grand Central Dispatch, blocks and OpenCL. So, most of the sessions either expanded on this directly or offhandedly mentioned “there’s an API for that now – and it’s fully XYZ-enabled” (insert one of the technologies above).

These things have become possible because CPU chips had run into a clock frequency “sound barrier”; 3GHz is about the maximum current silicon can do without extensive and expensive cooling or exotic technology. So multicore has become the solution du jour: all Apple computers now have at least 2 core, and the top machine has 8 (16 virtual). Expect that number to double every 2 years, at least.

But for years multi-processor machines were hard to program. About 14 years ago, at another WWDC I bought a Genesis MP 528: this Mac clone had 4 PowerPC 604 processors running at a blistering 132MHz. It didn’t have much caching on those chips, and only Photoshop and a few other specialized apps could see more than one CPU, and that only for image filters. In two years the first PowerPC G3 CPU card, with a single processor but caching, running at 300MHz, had about the same Photoshop performance – and that performance was then available to all apps. So why didn’t more apps take advantage of the 4 CPUs? The classic Mac System 7 (to 9) had no easy way to allow for this; there was a very primitive multiprocessing API but the system was pretty much locked out of it.

As said in the keynote, Snow Leopard will support only Intel Macs; PowerPC Macs are, therefore, stuck in the Leopard era, and only some few bug fixes will appear on 10.5, then it’s over. I couldn’t find hard figures comparing the installed base; I’ve seen percentages quoted of between 10 and 35% of Macs Macs still in use being PowerPCs. I personally didn’t think this would dip below 25% before 2011; then again, as a stockholder, I’m glad Apple sold so many new Macs recently…

Some people question why PowerPC users will be left out of the Snow Leopard advantages, and I think I know why. While the top 4-CPU PowerPC machines still can hold their own with more modern machines under certain circumstances, the vast majority of PowerPC Macs have only 1 CPU; only a few big desktops have 2, and even fewer have 4. Most advantages of Snow Leopard come into play when you have at least 2 CPU cores, and there’s serious testing and bug fixing to be done for supporting an entire architecture. Apple probably just weighed those factors (with better numbers than I have available) and decided it wouldn’t work out.

Positives of the new Clang/LLVM combo: better compiler speed, better code optimization – both still starting out but they’ve more power in reserve, while the current gcc compiler and backends are pretty much maxed out; way better error messages, the Clang static analyzer is just awesome (a word I usually hesitate to use, but this really is!); lots of goodies to come from tighter integration with Xcode. Negatives: may still generate wrong/inefficient code in some circumstances; no C++ support yet (I don’t care myself about this one).

A sleeper advantage is, also, that the intermediate (LLVM) bytecode generated by Clang could possibly be stored as such inside executables, and be just-in-time compiled for execution on any target CPU. In other words, the same executable could run on a new machine Apple puts out, even if it has a new CPU chip/architecture, as long as the JIT compiler is in place for that; application developers wouldn’t have know (or care).

Regarding blocks (or “closures”, as they’re known in other places), they’re a syntactic convenience for programmers to pass executable code as data. As such, they make programs more readable. What makes them inordinately powerful in Snow Leopard is that they’re also the basic executable units for all of the cool new multiprocessing stuff in Grand Central Dispatch. Therefore, with a little discipline, it becomes easy for developers to chop up tasks into little slices than can be executed in parallel by however many CPU cores (or, with OpenCL, GPU units) are available to do them; and for the first time anywhere I know of, this facility is available throughout the system, even at a quite low level.

So, am I running off to convert all of my code to the new technologies? Well, yes and no. Many things still have to be done in a serial manner, and the system will do others in parallel behind my back. Also, it seems that writing a generic application that runs on both 10.5 and 10.6 (using the new stuff) is tricky; I’m still investigating how to best do it. Stay tuned for developments…

Posted by 0xced:

Rainer Brockerhoff wrote:

   [task launch]; 
   [NSApp terminate:nil];

No need to pass the calling program’s process identifier, and it works from Tiger (10.4) on up.

Although unlikely, the task may be faster to execute than [NSApp terminate:] and the relaunch process would thus fail. By listening to the termination of the calling process, you are guaranteed to always relaunch.
Edit: I’m wrong, Rainer just pointed to me that the task can’t terminate since its first line is a read on the input pipe and it will block there.

Cédric Luthi has posted another take on the mechanics of reopening a System Preferences pane (or is it panel?). Worth a read; however, I would propose a shorter piece of code for his relaunch snippet, combining two of my recent posts:

int main(int argc, char **argv) { 
   char dummy; 
   read(STDIN_FILENO, &dummy, 1); 
   CFURLRef url = CFURLCreateFromFileSystemRepresentation(kCFAllocatorDefault, (UInt8*)argv[1], strlen(argv[1]), FALSE); 
   CFArrayRef aurl = CFArrayCreate(kCFAllocatorDefault, (const void**)&url, 1, NULL);
   FSRef ref;
   if (LSFindApplicationForInfo(0, CFSTR("com.apple.systempreferences"), NULL, &ref, NULL)==noErr) {
      LSApplicationParameters parms = {0,kLSLaunchDefaults,&ref,NULL,NULL,NULL,NULL};
      LSOpenURLsWithRole(aurl, kLSRolesAll, NULL, &parms, NULL, 0);
      }
   }
}

and the code to launch this tool (from within the preference panel itself) is:

   NSTask* task = [[NSTask alloc] init]; 
   [task setLaunchPath:@"/path/to/tool"]; 
   [task setArguments:[NSArray arrayWithObject:[[NSBundle bundleForClass:[self class]] bundlePath]]]; 
   [task setStandardInput:[NSPipe pipe]]; 
   [task launch]; 
   [NSApp terminate:nil];

No need to pass the calling program’s process identifier, and it works from Tiger (10.4) on up.