Has there ever been a UUID collision?
The chances of a duplicate UUID number being produced is billions of billions to one against.The chance of these being acquired by the same application are a million to one.The chance of this causing a fault might be 1 in 100.The chance that somebody investigated a one-off failure which caused a single transaction to fail and found a duplicate UUID was the cause are also quite small.UUIDs are made large enough that a duplicate is extremely unlikely to ever occur. On top of that, with the millions issued every year, the chance of them appearing in the same app and causing a problem is also extremely low.So its not a problem in practice.
Why does carrier-sense multiple access with collision detection use a random delay?
Ever tried to pass by someone coming from the opposite direction right towards you? You can either keep walking, move left or move right. It ends up in a deadlock if you both mirror each others' moves.Same for CSMA/CD. If the retries were attempted according to some recipe, chances are someone else uses the same recipe and the two bump into each other every time, forever. By picking random delays, even if a collision does occur, eventually someone will make room.
How do I detect EOF in Java?
If you are reading a binary file, then read data into byte arrays, like this:byte[] data = new byte[1000];int sizeRead = in.read(data);sizeRead will contain the number of bytes read, or -1 if end of file.If you are reading a text file, then BufferedReader is useful:BufferedReader reader = new BufferedReader(new FileReader(file));String line = reader.nextLine();The variable ‘line’ will contain the next line of data, or will be null if end of file.
I've got slow ethernet communication between two computers connected by hub... what should I do?
I'm using a hub to share a DSL internet connection between 2 computers and my XBOX. I suppose that, since we're already there, I can network the 2 PCs so I can file share and stuff like that. My main PC uses XP professional, the other one uses windows 2000 pro. I can call up a directory in the 2000 machine from my XP, but when I try to copy a, lets say, 5 MB file... the copying takes a lifetime. Now, I'm not a CCNA, but I know enough to say that there seems to be network collision occuring when I try to communicate directly between the 2 PCs. When one of them tries to transmit, both NICs xmit lights glow and the collision detection light on my hub goes on too. Then there's a pause, which I assume is the Ethernet Collision Detection algorithm going on... then it repeats until the file is eventually xmitted... long time later. Must point out that the internet connection works fine for all 3 pieces of equipment. What should I check on them so they can intercommunicate at top speed?
What is the range limitation of 5G?
It’s basically another multi-band, radio solution. So, it’s gonna be about 300 feet, in common hardware installations. The more you try to boost the bandwidth, the more you shorten the broadcast range, because your router / access point, has to DETECT errors on the radio network.That’s the way Carrier-sense multiple access with collision detection (CSMA/CD) works. The transmitting device must detect errors, and determine if re-transmission is needed.
Why are clipping bugs still so common in video games?
Okay, let’s get our definitions straight.Clipping, in computer graphics, correctly refers to a graphic element, such as a polygon, being chopped against the view frustum or some other graphic element, to reduce the visible area of the element. Clipping is an old and well known technique for speeding up graphics rendering.One game in the 1990s had a cheat code that referred awkwardly to collision detection as “clipping a movement vector.” As a result, a bunch of gamers and other unwashed heathens mistakenly refer to collision detection as clipping. Collision detection is not clipping. It is collision detection.All the videos on YouTube describing “clipping bugs” are in fact collision detection bugs. It is strictly bush league to confuse the two. So don’t do that. You may say that two graphic elements intersect in an unwanted manner, if hair disappears into armor and the like.“Walking off the world” type collision detection bugs occur in because, in many games, it’s necessary to create a collision geometry that is separate from graphic geometry. This collision geometry is an invisible barrier keeps you from walking off the world, or into that complicated rock structure, or into that fountain of molten lava, and so on. While much of the collision geometry can be created automatically, some is typically created by artists when modelling the world. Since artists are humans, they can mistakenly leave small holes in the collision geometry.Practical testing for collision geometry errors is very time consuming. A game tester has to basically walk around the entire world trying to walk, jump, and somersault out of the world. Since it’s almost impossible to do this canonically for every level, usually there’s some gamer out there who manages to find the one tiny hole that the developers left in the collision geometry by mistake. And they jump through it and flyyyyyy into space and land in hell.Anyway, collision geometry bugs are really not that common. What is common though, is to have millions of gamers, who have nothing better to do all day than to walk into every single rock and wall in the game, looking for that one wall or rock that has incorrect collision geometry on it, so they can jump through it and flyyyyyy into space and land in hell.
How is it possible for planes to collide in mid air flight? What are some examples of this happening?
It almost never happens with airliners for a number of reasons:Two pilots per aircraftAlways fly under instrument flight rules, so they’re being watched by air traffic control radar where available. In places where radar isn’t available, like on over the ocean, there are specific corridors and procedures to followTCAS (Traffic collision avoidance system - Wikipedia) so your aircraft is has autonomous collision detection and avoidanceUnfortunately, collisions even with those things going for you aren’t completely unknown. There was a collision a few years ago where a business jet collided with an airliner. The business jet survived, the airliner did not. There is a lot of finger pointing - the Brazilian authorities blamed the American pilots of the business jet, but the American NTSB says that Brazilian air traffic control screwed up and put them on a collision course. The NTSB has an amazing reputation of honesty, so I know who I believe. But the pilots face criminal charges if they ever end up in Brazil.Where collisions are more common is in general aviation. General aviation aircraft don’t always fly under instrument flight rules, they often don’t have two pilots, the pilot that is there is often not all that experienced or current, and they don’t usually have TCAS. Some of them don’t even have radios or transponders. A lot of them fly under 3,000 feet above the ground, which is more congested and it’s harder to see each other against the ground clutter.
Which programming language do I need to use for creation of a game?
I have lots of ideas about creating amazing games and I would like to proceed learning programming languages and other things to produce my own games. It's not going to be a simple games such as 30-40 mb, but 4-5 GB or more with high graphics. So, what are the programming languages and other design programs I must learn first before? I will appreciate your answers! Thank you
Why does wireless networking use CSMA/CA instead of CSMA/CD?
Over a wired medium like an Ethernet cable it is possible to detect a collision (CD) by measuring the power level on the medium itself. Measuring the power level in a RF environment is not possible with the precision required to detect a packet collision and therefore CD is not possible but collision avoidance is the best we can get. Collision detection would allow a network to have better performances than what it is possible to accomplish with Collision Avoidance, that requires ACK packets and therefore create overhead. In order to overcome these performance limitations many wireless networks used TDMA based approached to medium access control rather than CSMA/CA. Particularly in Point-to-multipoint Wireless networks where directional antennas are deployed, the hidden terminal issue can negatively impact the overall network performances in a significant way. Therefore CSMA/CA is not a solution to provide good throughput. TMDA based solutions are much more common in order to avoid the hidden terminal issue.