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  • How to convert DateTime to a number with a precision greater than days in T-SQL?

    - by Jader Dias
    Both queries below translates to the same number SELECT CONVERT(bigint,CONVERT(datetime,'2009-06-15 15:00:00')) SELECT CAST(CONVERT(datetime,'2009-06-15 23:01:00') as bigint) Result 39978 39978 The generated number will be different only if the days are different. There is any way to convert the DateTime to a more precise number, as we do in .NET with the .Ticks property? I need at least a minute precision.

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  • Determine if it has been 6 months since birthday in c#

    - by Longball27
    Hi, Sorry if this is a duplicate, but i think I've seen enough of Google for one day! My application needs to adjust a clients current age by +0.5 if it has been 6 months since their birthday. The code should look something like this, but how many ticks would there be in 6 months? if (DateTime.Today - dateOfBirth.Date > new TimeSpan(6)) { adjust = 0.5M; } else { adjust = 0M; } Thanks in advance

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  • Gnuplot - splot matrix csv data

    - by Jakub Czaplicki
    How can I plot (a 3D plot) a matrix in Gnuplot having such data structure. I cannot find a way to use the first row and column as a x and y ticks (or to ignore them) ,5,6,7,8 1,-6.20,-6.35,-6.59,-6.02 2,-6.39,-6.52,-6.31,-6.00 3,-6.36,-6.48,-6.15,-5.90 4,-5.79,-5.91,-5.87,-5.46 Is the splot 'data.csv' matrix the correct parameter to use ?

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  • Running on Windows CE 6 'and' Windows XP

    - by Psychic
    Is it possible to create a small program that will run, without recompiling and without emulators, on both Windows CE 6 AND Windows XP SP3? From my knowledge, this isn't possible. Source code needs to be recompiled for the target platform. However, a hardware manufacturer for embedded boards is claiming otherwise. The application isn't anything complex, just a simple benchmarking tool analysing floating point operations, CPU ticks etc, and displaying the results on a plain GUI.

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  • Generics vs Object performance

    - by Risho
    I'm doing practice problems from MCTS Exam 70-536 Microsft .Net Framework Application Dev Foundation, and one of the problems is to create two classes, one generic, one object type that both perform the same thing; in which a loop uses the class and iterated over thousand times. And using the timer, time the performance of both. There was another post at C# generics question that seeks the same questoion but nonone replied. Basically if in my code I run the generic class first it takes loger to process. If I run the object class first than the object class takes longer to process. The whole idea was to prove that generics perform faster. I used the original users code to save me some time. I didn't particularly see anything wrong with the code and was puzzled by the outcome. Can some one explain why the unusual results? Thanks, Risho Here is the code: class Program { class Object_Sample { public Object_Sample() { Console.WriteLine("Object_Sample Class"); } public long getTicks() { return DateTime.Now.Ticks; } public void display(Object a) { Console.WriteLine("{0}", a); } } class Generics_Samle<T> { public Generics_Samle() { Console.WriteLine("Generics_Sample Class"); } public long getTicks() { return DateTime.Now.Ticks; } public void display(T a) { Console.WriteLine("{0}", a); } } static void Main(string[] args) { long ticks_initial, ticks_final, diff_generics, diff_object; Object_Sample OS = new Object_Sample(); Generics_Samle<int> GS = new Generics_Samle<int>(); //Generic Sample ticks_initial = 0; ticks_final = 0; ticks_initial = GS.getTicks(); for (int i = 0; i < 50000; i++) { GS.display(i); } ticks_final = GS.getTicks(); diff_generics = ticks_final - ticks_initial; //Object Sample ticks_initial = 0; ticks_final = 0; ticks_initial = OS.getTicks(); for (int j = 0; j < 50000; j++) { OS.display(j); } ticks_final = OS.getTicks(); diff_object = ticks_final - ticks_initial; Console.WriteLine("\nPerformance of Generics {0}", diff_generics); Console.WriteLine("Performance of Object {0}", diff_object); Console.ReadKey(); } }

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  • How long does it take each thread timeslice in Windows XP ?

    - by IHawk
    I am trying to find out how long does it take each thread timeslice (quantum) in Windows but the only information that I found out is about the clock ticks being from 15 to 20ms or 20-30ms. How can I find this information ? I think it may vary from OS to OS, but I am not certain. I appreciate any suggestion on this subject. Thank you.

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  • PHP using Declare ? What is a tick?

    - by ArneRie
    Iam a little bit confused by php function declare. What exactly is an single tick, i thought 1 tick = one line of code? But if i use: function myfunc() { print "Tick"; } register_tick_function("myfunc"); declare(ticks=1) { echo 'foo!bar'; } The script prints : "Tick" 2 Times??

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  • In-app settings controlled by plist?

    - by cannyboy
    Is there a library or good tutorial which covers creating in-app settings, like this: http://img.skitch.com/20090625-s8bf6ahybwe3cesd1id38h3nt.jpg What I would like is if it: doesn't use the built-in Settings app is controlled by a plist file with various Dictionaries and Arrays creates a nice looking table view allows text fields as well as switches and sliders and ticks etc doesn't have any of the annoying problems I've come across when trying to build my own version (not scrolling to show the textfield, cells disappearing) It would appear that the iphone dev world is crying out for such a thing. THANK YOU!

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  • why my test performance class gives me inconsistent results even after proper warm-up?

    - by colinfang
    i made a class which helps me measure time for any methods in Ticks. Basically, it runs testing method 100x, and force GC, then it records time taken for another 100x method runs. x64 release ctrl+f5 VS2012/VS2010 the results are following: 2,914 2,909 2,913 2,909 2,908 2,907 2,909 2,998 2,976 2,855 2,446 2,415 2,435 2,401 2,402 2,402 2,399 2,401 2,401 2,400 2,399 2,400 2,404 2,402 2,401 2,399 2,400 2,402 2,404 2,403 2,401 2,403 2,401 2,400 2,399 2,414 2,405 2,401 2,407 2,399 2,401 2,402 2,401 2,404 2,401 2,404 2,405 2,368 1,577 1,579 1,626 1,578 1,576 1,578 1,577 1,577 1,576 1,578 1,576 1,578 1,577 1,578 1,576 1,578 1,577 1,579 1,585 1,576 1,579 1,577 1,579 1,578 1,579 1,577 1,578 1,577 1,578 1,576 1,578 1,577 1,578 1,599 1,579 1,578 1,582 1,576 1,578 1,576 1,579 1,577 1,578 1,577 1,591 1,577 1,578 1,578 1,576 1,578 1,576 1,578 As you can see there are 3 phases, first is ~2,900, second is ~2,400, then ~1,550 What might be the reason to cause it? the test performance class code follows: public static void RunTests(Func<long> myTest) { const int numTrials = 100; Stopwatch sw = new Stopwatch(); double[] sample = new double[numTrials]; Console.WriteLine("Checksum is {0:N0}", myTest()); sw.Start(); myTest(); sw.Stop(); Console.WriteLine("Estimated time per test is {0:N0} ticks\n", sw.ElapsedTicks); for (int i = 0; i < numTrials; i++) { myTest(); } GC.Collect(); string testName = myTest.Method.Name; Console.WriteLine("----> Starting benchmark {0}\n", myTest.Method.Name); for (int i = 0; i < numTrials; i++) { sw.Restart(); myTest(); sw.Stop(); sample[i] = sw.ElapsedTicks; } double testResult = DataSetAnalysis.Report(sample); for (int j = 0; j < numTrials; j = j + 5) Console.WriteLine("{0,8:N0} {1,8:N0} {2,8:N0} {3,8:N0} {4,8:N0}", sample[j], sample[j + 1], sample[j + 2], sample[j + 3], sample[j + 4]); Console.WriteLine("\n----> End of benchmark"); }

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  • C#/.NET Little Wonders: Using &lsquo;default&rsquo; to Get Default Values

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Today’s little wonder is another of those small items that can help a lot in certain situations, especially when writing generics.  In particular, it is useful in determining what the default value of a given type would be. The Problem: what’s the default value for a generic type? There comes a time when you’re writing generic code where you may want to set an item of a given generic type.  Seems simple enough, right?  We’ll let’s see! Let’s say we want to query a Dictionary<TKey, TValue> for a given key and get back the value, but if the key doesn’t exist, we’d like a default value instead of throwing an exception. So, for example, we might have a the following dictionary defined: 1: var lookup = new Dictionary<int, string> 2: { 3: { 1, "Apple" }, 4: { 2, "Orange" }, 5: { 3, "Banana" }, 6: { 4, "Pear" }, 7: { 9, "Peach" } 8: }; And using those definitions, perhaps we want to do something like this: 1: // assume a default 2: string value = "Unknown"; 3:  4: // if the item exists in dictionary, get its value 5: if (lookup.ContainsKey(5)) 6: { 7: value = lookup[5]; 8: } But that’s inefficient, because then we’re double-hashing (once for ContainsKey() and once for the indexer).  Well, to avoid the double-hashing, we could use TryGetValue() instead: 1: string value; 2:  3: // if key exists, value will be put in value, if not default it 4: if (!lookup.TryGetValue(5, out value)) 5: { 6: value = "Unknown"; 7: } But the “flow” of using of TryGetValue() can get clunky at times when you just want to assign either the value or a default to a variable.  Essentially it’s 3-ish lines (depending on formatting) for 1 assignment.  So perhaps instead we’d like to write an extension method to support a cleaner interface that will return a default if the item isn’t found: 1: public static class DictionaryExtensions 2: { 3: public static TValue GetValueOrDefault<TKey, TValue>(this Dictionary<TKey, TValue> dict, 4: TKey key, TValue defaultIfNotFound) 5: { 6: TValue value; 7:  8: // value will be the result or the default for TValue 9: if (!dict.TryGetValue(key, out value)) 10: { 11: value = defaultIfNotFound; 12: } 13:  14: return value; 15: } 16: } 17:  So this creates an extension method on Dictionary<TKey, TValue> that will attempt to get a value using the given key, and will return the defaultIfNotFound as a stand-in if the key does not exist. This code compiles, fine, but what if we would like to go one step further and allow them to specify a default if not found, or accept the default for the type?  Obviously, we could overload the method to take the default or not, but that would be duplicated code and a bit heavy for just specifying a default.  It seems reasonable that we could set the not found value to be either the default for the type, or the specified value. So what if we defaulted the type to null? 1: public static TValue GetValueOrDefault<TKey, TValue>(this Dictionary<TKey, TValue> dict, 2: TKey key, TValue defaultIfNotFound = null) // ... No, this won’t work, because only reference types (and Nullable<T> wrapped types due to syntactical sugar) can be assigned to null.  So what about a calling parameterless constructor? 1: public static TValue GetValueOrDefault<TKey, TValue>(this Dictionary<TKey, TValue> dict, 2: TKey key, TValue defaultIfNotFound = new TValue()) // ... No, this won’t work either for several reasons.  First, we’d expect a reference type to return null, not an “empty” instance.  Secondly, not all reference types have a parameter-less constructor (string for example does not).  And finally, a constructor cannot be determined at compile-time, while default values can. The Solution: default(T) – returns the default value for type T Many of us know the default keyword for its uses in switch statements as the default case.  But it has another use as well: it can return us the default value for a given type.  And since it generates the same defaults that default field initialization uses, it can be determined at compile-time as well. For example: 1: var x = default(int); // x is 0 2:  3: var y = default(bool); // y is false 4:  5: var z = default(string); // z is null 6:  7: var t = default(TimeSpan); // t is a TimeSpan with Ticks == 0 8:  9: var n = default(int?); // n is a Nullable<int> with HasValue == false Notice that for numeric types the default is 0, and for reference types the default is null.  In addition, for struct types, the value is a default-constructed struct – which simply means a struct where every field has their default value (hence 0 Ticks for TimeSpan, etc.). So using this, we could modify our code to this: 1: public static class DictionaryExtensions 2: { 3: public static TValue GetValueOrDefault<TKey, TValue>(this Dictionary<TKey, TValue> dict, 4: TKey key, TValue defaultIfNotFound = default(TValue)) 5: { 6: TValue value; 7:  8: // value will be the result or the default for TValue 9: if (!dict.TryGetValue(key, out value)) 10: { 11: value = defaultIfNotFound; 12: } 13:  14: return value; 15: } 16: } Now, if defaultIfNotFound is unspecified, it will use default(TValue) which will be the default value for whatever value type the dictionary holds.  So let’s consider how we could use this: 1: lookup.GetValueOrDefault(1); // returns “Apple” 2:  3: lookup.GetValueOrDefault(5); // returns null 4:  5: lookup.GetValueOrDefault(5, “Unknown”); // returns “Unknown” 6:  Again, do not confuse a parameter-less constructor with the default value for a type.  Remember that the default value for any type is the compile-time default for any instance of that type (0 for numeric, false for bool, null for reference types, and struct will all default fields for struct).  Consider the difference: 1: // both zero 2: int i1 = default(int); 3: int i2 = new int(); 4:  5: // both “zeroed” structs 6: var dt1 = default(DateTime); 7: var dt2 = new DateTime(); 8:  9: // sb1 is null, sb2 is an “empty” string builder 10: var sb1 = default(StringBuilder()); 11: var sb2 = new StringBuilder(); So in the above code, notice that the value types all resolve the same whether using default or parameter-less construction.  This is because a value type is never null (even Nullable<T> wrapped types are never “null” in a reference sense), they will just by default contain fields with all default values. However, for reference types, the default is null and not a constructed instance.  Also it should be noted that not all classes have parameter-less constructors (string, for instance, doesn’t have one – and doesn’t need one). Summary Whenever you need to get the default value for a type, especially a generic type, consider using the default keyword.  This handy word will give you the default value for the given type at compile-time, which can then be used for initialization, optional parameters, etc. Technorati Tags: C#,CSharp,.NET,Little Wonders,default

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  • 3½" PATA Western Digital Caviar SE (250MB) makes steady ticking sound when idle

    - by intuited
    I've started to notice a ticking sound emanating from my WD2500JB. It is not alarmingly loud. The sound seems to occur only when the drive has been idle for some time, and will cease upon (some?) disk activity. The sound has a regular, steady cadence of somewhere between about 4 and 6 ticks per second. I'm not entirely certain that it just started making these sounds, since I previously had the drive — mounted in a USB enclosure — stored out of earshot, and only recently moved it to where I can hear it. The SMART attributes for the drive do not indicate any problems. I did have some errors to clean up recently (since I started noticing the sounds). The errors occurred on an ext3 filesystem. The drive had been powered down while mounted a few times prior to that fsck. Is this cause for alarm? Should I scrap the drive on principle?

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  • Simple dig output?

    - by knocte
    In a script I want to be able to write an IP address to somewhere easily, so I thought using dig (or a similar command) with back-ticks. However the simplest output I've been able to come up to wrt dig parameters is > dig -t A +noall +answer www.google.com www.google.com. 300 IN A 173.194.66.106 www.google.com. 300 IN A 173.194.66.104 Any way (extra arg, different tool instead of dig?) to get rid of the junk apart from the IP address?? (And please don't tell me to use sed.) Thanks

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  • How can I make Excel correlate data from two data sets into a single graph?

    - by Tom Ritter
    I have two datasets, one being sparser than the other. They look like this: Data Set 1: 4 50 5 55 6 60 7 70 8 80 Data Set 2: 4 10 6 20 8 30 I have several hundred points instead of this few. I want them in the same graph, the X axis being 4-8, the y axis being 0-100ish, and two lines, one for each data set. What I get is two lines, not correlated at all along the X axis, and the X axis being labeled from one of the two datasets, with the labels being wrong for the other. The smaller data set is one-point-per-tick on the x axis, when I need it to skip ticks and actually line up with the other data set. Not married to excel, willing to try this in something else if it's free.

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  • Issuing Current Time Increments in StreamInsight (A Practical Example)

    The issuing of a Current Time Increment, Cti, in StreamInsight is very definitely one of the most important concepts to learn if you want your Streams to be responsive. A full discussion of how to issue Ctis is beyond the scope of this article but a very good explanation in addition to Books Online can be found in these three articles by a member of the StreamInsight team at Microsoft, Ciprian Gerea. Time in StreamInsight Series http://blogs.msdn.com/b/streaminsight/archive/2010/07/23/time-in-streaminsight-i.aspx http://blogs.msdn.com/b/streaminsight/archive/2010/07/30/time-in-streaminsight-ii.aspx http://blogs.msdn.com/b/streaminsight/archive/2010/08/03/time-in-streaminsight-iii.aspx A lot of the problems I see with unresponsive or stuck streams on the MSDN Forums are to do with how Ctis are enqueued or in a lot of cases not enqueued. If you enqueue events and never enqueue a Cti then StreamInsight will be perfectly happy. You, on the other hand, will never see data on the output as you have not told StreamInsight to flush the stream. This article deals with a specific implementation problem I had recently whilst working on a StreamInsight project. I look at some possible options and discuss why they would not work before showing the way I solved the problem. The stream of data I was dealing with on this project was very bursty that is to say when events were flowing they came through very quickly and in large numbers (1000 events/sec), but when the stream calmed down it could be a few seconds between each event. When enqueuing events into the StreamInsight engne it is best practice to do so with a StartTime that is given to you by the system producing the event . StreamInsight processes events and it doesn't matter whether those events are being pushed into the engine by a source system or the events are being read from something like a flat file in a directory somewhere. You can apply the same logic and temporal algebra to both situations. Reading from a file is an excellent example of where the time of the event on the source itself is very important. We could be reading that file a long time after it was written. Being able to read the StartTime from the events allows us to define windows that will hold the correct sets of events. I was able to do this with my stream but this is where my problems started. Below is a very simple script to create a SQL Server table and populate it with sample data that will show exactly the problem I had. CREATE TABLE [dbo].[t] ( [c1] [int] PRIMARY KEY, [c2] [datetime] NULL ) INSERT t VALUES (1,'20100810'),(2,'20100810'),(3,'20100810') Column c2 defines the StartTime of the event on the source and as you can see the values in all 3 rows of data is the same. If we read Ciprian’s articles we know that we can define how Ctis get injected into the stream in 3 different places The Stream Definition The Input Factory The Input Adapter I personally have always been a fan of enqueing Ctis through the factory. Below is code typical of what I would use to do this On the class itself I do some inheriting public class SimpleInputFactory : ITypedInputAdapterFactory<SimpleInputConfig>, ITypedDeclareAdvanceTimeProperties<SimpleInputConfig> And then I implement the following function public AdapterAdvanceTimeSettings DeclareAdvanceTimeProperties<TPayload>(SimpleInputConfig configInfo, EventShape eventShape) { return new AdapterAdvanceTimeSettings( new AdvanceTimeGenerationSettings(configInfo.CtiFrequency, TimeSpan.FromTicks(-1)), AdvanceTimePolicy.Adjust); } The configInfo .CtiFrequency property is a value I pass through to define after how many events I want a Cti to be injected and this in turn will flush through the stream of data. I usually pass a value of 1 for this setting. The second parameter determines the CTI timestamp in terms of a delay relative to the events. -1 ticks in the past results in 1 tick in the future, i.e., ahead of the event. The problem with this method though is that if consecutive events have the same StartTime then only one of those events will be enqueued. In this example I use the following to define how I assign the StartTime of my events currEvent.StartTime = (DateTimeOffset)dt.c2; If I go ahead and run my StreamInsight process with this configuration i can see on the output adapter that two events have been removed To see this in a little more depth I can use the StreamInsight Debugger and see what happens internally. What is happening here is that the first event arrives and a Cti is injected with a time of 1 tick after the StartTime of that event (Also the EndTime of the event). The second event arrives and it has a StartTime of before the Cti and even though we specified AdvanceTimePolicy.Adjust on the factory we know that a point event can never be adjusted like this and the event is dropped. The same happens for the third event as well (The second and third events get trumped by the Cti). For a more detailed discussion of why this happens look here http://www.sqlis.com/sqlis/post/AdvanceTimePolicy-and-Point-Event-Streams-In-StreamInsight.aspx We end up with a single event being pushed into the output adapter and our result now makes sense. The next way I tried to solve this problem by changing the value of the second parameter to TimeSpan.Zero Here is how my factory code now looks public AdapterAdvanceTimeSettings DeclareAdvanceTimeProperties<TPayload>(SimpleInputConfig configInfo, EventShape eventShape) { return new AdapterAdvanceTimeSettings( new AdvanceTimeGenerationSettings(configInfo.CtiFrequency, TimeSpan.Zero), AdvanceTimePolicy.Adjust); } What I am doing here is declaring a policy that says inject a Cti together with every event and stamp it with a StartTime that is equal to the start time of the event itself (TimeSpan.Zero). This method has plus points as well as a downside. The upside is that no events will be lost by having the same StartTime as previous events. The Downside is that because the Cti is declared with the StartTime of the event itself then it does not actually flush that particular event because in the StreamInsight algebra, a Cti commits only those events that occurred strictly before them. To flush the events we need a Cti to be enqueued with a greater StartTime than the events themselves. Here is what happened when I ran this configuration As you can see all we got through was the Cti and none of the events. The debugger output shows the stamps on the Cti and the events themselves. Because the Cti issued has the same timestamp (StartTime) as the events then none of the events get flushed. I was nearly there but not quite. Because my stream was bursty it was possible that the next event would not come along for a few seconds and this was far too long for an event to be enqueued and not be flushed to the output adapter. I needed another solution. Two possible solutions crossed my mind although only one of them made sense when I explored it some more. Where multiple events have the same StartTime I could add 1 tick to the first event, two to the second, three to third etc thereby giving them unique StartTime values. Add a timer to manually inject Ctis The problem with the first implementation is that I would be giving the events a new StartTime. This would cause me the following problems If I want to define windows over the stream then some events may not be captured in the right windows and therefore any calculations on those windows I did would be wrong What would happen if we had 10,000 events with the same StartTime? I would enqueue them with StartTime + n ticks. Along comes a genuine event with a StartTime of the very first event + 1 tick. It is now too far in the past as far as my stream is concerned and it would be dropped. Not what I would want to do at all. I decided then to look at the Timer based solution I created a timer on my input adapter that elapsed every 200ms. private Timer tmr; public SimpleInputAdapter(SimpleInputConfig configInfo) { ctx = new SimpleTimeExtractDataContext(configInfo.ConnectionString); this.configInfo = configInfo; tmr = new Timer(200); tmr.Elapsed += new ElapsedEventHandler(t_Elapsed); tmr.Enabled = true; } void t_Elapsed(object sender, ElapsedEventArgs e) { ts = DateTime.Now - dtCtiIssued; if (ts.TotalMilliseconds >= 200 && TimerIssuedCti == false) { EnqueueCtiEvent(System.DateTime.Now.AddTicks(-100)); TimerIssuedCti = true; } }   In the t_Elapsed event handler I find out the difference in time between now and when the last event was processed (dtCtiIssued). I then check to see if that is greater than or equal to 200ms and if the last issuing of a Cti was done by the timer or by a genuine event (TimerIssuedCti). If I didn’t do this check then I would enqueue a Cti every time the timer elapsed which is not something I wanted. If the difference between the two times is greater than or equal to 500ms and the last event enqueued was by a real event then I issue a Cti through the timer to flush the event Queue, otherwise I do nothing. When I enqueue the Ctis into my stream in my ProduceEvents method I also set the values of dtCtiIssued and TimerIssuedCti   currEvent = CreateInsertEvent(); currEvent.StartTime = (DateTimeOffset)dt.c2; TimerIssuedCti = false; dtCtiIssued = currEvent.StartTime; If I go ahead and run this configuration I see the following in my output. As we can see the first Cti gets enqueued as before but then another is enqueued by the timer and because this has a later timestamp it flushes the enqueued events through the engine. Conclusion Hopefully this has shown how the enqueuing of Ctis can have a dramatic effect on the responsiveness of your output in StreamInsight. Understanding the temporal nature of the product is for me one of the most important things you can learn. I have attached my solution for the demos. It is all in one project and testing each variation is a simple matter of commenting and un-commenting the parts in the code we have been dealing with here.

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  • Event-based server-gameloop in a server based game

    - by Chris
    I know that this site is full of questions about fixed gameloops and variable gameloops and different types of threading. But I coult find barely nothing that is related to server loops. The server has no screen to draw on. It could just run as fast as possible, but of course this makes no sense. But should it really use single "ticks" and send the updates periodically after each tick and wait for the next "tick" to update its state. Is it applicable to replace the gameloop by multilpe events? Suchs as incoming network traffic or timers? I often heared that a gameloop should be determistic, but does it really matter? For instance, when you play a shooter game against humand players and/or AI you proably would never be ably to repeat the same input twice. Is it a good idea to lose determistic behavior if it is nearly impossible to reprodruce the same input twice? So this question is more or less about whether an strictly event-based gameloop is adviseable or not and what are the pros and cons. I could imagene that an event-based gameloop could perform much faster and smoother, since you don't have bug CPU-spikes during the beginning of a new "tick". The fact that I could not find much about an event-based gameloop for servers leads me to the conclusion that inefficient or too complicated to get a real benefit from it. I'm sure if this is enough to get an idea from what I'm interessted to know, but I hope so.

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  • Why do UInt16 arrays seem to add faster than int arrays?

    - by scraimer
    It seems that C# is faster at adding two arrays of UInt16[] than it is at adding two arrays of int[]. This makes no sense to me, since I would have assumed the arrays would be word-aligned, and thus int[] would require less work from the CPU, no? I ran the test-code below, and got the following results: Int for 1000 took 9896625613 tick (4227 msec) UInt16 for 1000 took 6297688551 tick (2689 msec) The test code does the following: Creates two arrays named a and b, once. Fills them with random data, once. Starts a stopwatch. Adds a and b, item-by-item. This is done 1000 times. Stops the stopwatch. Reports how long it took. This is done for int[] a, b and for UInt16 a,b. And every time I run the code, the tests for the UInt16 arrays take 30%-50% less time than the int arrays. Can you explain this to me? Here's the code, if you want to try if for yourself: public static UInt16[] GenerateRandomDataUInt16(int length) { UInt16[] noise = new UInt16[length]; Random random = new Random((int)DateTime.Now.Ticks); for (int i = 0; i < length; ++i) { noise[i] = (UInt16)random.Next(); } return noise; } public static int[] GenerateRandomDataInt(int length) { int[] noise = new int[length]; Random random = new Random((int)DateTime.Now.Ticks); for (int i = 0; i < length; ++i) { noise[i] = (int)random.Next(); } return noise; } public static int[] AddInt(int[] a, int[] b) { int len = a.Length; int[] result = new int[len]; for (int i = 0; i < len; ++i) { result[i] = (int)(a[i] + b[i]); } return result; } public static UInt16[] AddUInt16(UInt16[] a, UInt16[] b) { int len = a.Length; UInt16[] result = new UInt16[len]; for (int i = 0; i < len; ++i) { result[i] = (ushort)(a[i] + b[i]); } return result; } public static void Main() { int count = 1000; int len = 128 * 6000; int[] aInt = GenerateRandomDataInt(len); int[] bInt = GenerateRandomDataInt(len); Stopwatch s = new Stopwatch(); s.Start(); for (int i=0; i<count; ++i) { int[] resultInt = AddInt(aInt, bInt); } s.Stop(); Console.WriteLine("Int for " + count + " took " + s.ElapsedTicks + " tick (" + s.ElapsedMilliseconds + " msec)"); UInt16[] aUInt16 = GenerateRandomDataUInt16(len); UInt16[] bUInt16 = GenerateRandomDataUInt16(len); s = new Stopwatch(); s.Start(); for (int i=0; i<count; ++i) { UInt16[] resultUInt16 = AddUInt16(aUInt16, bUInt16); } s.Stop(); Console.WriteLine("UInt16 for " + count + " took " + s.ElapsedTicks + " tick (" + s.ElapsedMilliseconds + " msec)"); }

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  • Input handling between game loops

    - by user48023
    This may be obvious and trivial for you but as I am a newbie in programming I come with a specific question. I have three loops in my game engine which are input-loop, update-loop and render-loop. Update-loop is set to 10 ticks per second with a fixed timestep, render-loop is capped at around 60 fps and the input-loop runs as fast as possible. I am using one of the Javascript frameworks which provide such things but it doesn't really matter. Let's say I am rendering a tile map and the view of which elements are rendered depends on camera-like movement variables which are modified during key pressing. This is only about camera/viewport and rendering, no game physics involved here. And now, how can I handle input events among these loops to keep consistent engine reaction? Am I supposed to read the current variable modified with input and do some needed calculations in a update-loop and share the result so it could be interpolated in a render-loop? Or read the input effect directly inside the render-loop and put needed calculations inside? I thought interpreting user input inside an update-loop with a low tick rate would be inaccurate and kind of unresponsive while rendering with interpolation in the final view. How it is done properly in games overall?

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  • How do you avoid jumping to a solution when under pressure? [closed]

    - by GlenPeterson
    When under a particularly strict programming deadline (like an hour), if I panic at all, my tendency is to jump into coding without a real plan and hope I figure it out as I go along. Given enough time, this can work, but in an interview it's been pretty unsuccessful, if not downright counter-productive. I'm not always comfortable sitting there thinking while the clock ticks away. Is there a checklist or are there techniques to recognize when you understand the problem well enough to start coding? Maybe don't touch the keyboard for the first 5-10 minutes of the problem? At what point do you give up and code a brute-force solution with the hope of reasoning out a better solution later? A related follow-up question might be, "How do you ensure that you are solving the right problem?" Or "When is it most productive to think and design more vs. code some experiments to and figure out the design later?" EDIT: One close vote already, but I'm not sure why. I wrote this in the first person, but I doubt I'm the only programmer to ever choke in an interview. Here is a list of techniques for taking a math test and another for taking an oral exam. Maybe I'm not expressing myself well, but I'm asking if there is a similar list of techniques for handling a programming problem under pressure?

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  • DataTable to JSON

    - by Joel Coehoorn
    I recently needed to serialize a datatable to JSON. Where I'm at we're still on .Net 2.0, so I can't use the JSON serializer in .Net 3.5. I figured this must have been done before, so I went looking online and found a number of different options. Some of them depend on an additional library, which I would have a hard time pushing through here. Others require first converting to List<Dictionary<>>, which seemed a little awkward and needless. Another treated all values like a string. For one reason or another I couldn't really get behind any of them, so I decided to roll my own, which is posted below. As you can see from reading the //TODO comments, it's incomplete in a few places. This code is already in production here, so it does "work" in the basic sense. The places where it's incomplete are places where we know our production data won't currently hit it (no timespans or byte arrays in the db). The reason I'm posting here is that I feel like this can be a little better, and I'd like help finishing and improving this code. Any input welcome. public static class JSONHelper { public static string FromDataTable(DataTable dt) { string rowDelimiter = ""; StringBuilder result = new StringBuilder("["); foreach (DataRow row in dt.Rows) { result.Append(rowDelimiter); result.Append(FromDataRow(row)); rowDelimiter = ","; } result.Append("]"); return result.ToString(); } public static string FromDataRow(DataRow row) { DataColumnCollection cols = row.Table.Columns; string colDelimiter = ""; StringBuilder result = new StringBuilder("{"); for (int i = 0; i < cols.Count; i++) { // use index rather than foreach, so we can use the index for both the row and cols collection result.Append(colDelimiter).Append("\"") .Append(cols[i].ColumnName).Append("\":") .Append(JSONValueFromDataRowObject(row[i], cols[i].DataType)); colDelimiter = ","; } result.Append("}"); return result.ToString(); } // possible types: // http://msdn.microsoft.com/en-us/library/system.data.datacolumn.datatype(VS.80).aspx private static Type[] numeric = new Type[] {typeof(byte), typeof(decimal), typeof(double), typeof(Int16), typeof(Int32), typeof(SByte), typeof(Single), typeof(UInt16), typeof(UInt32), typeof(UInt64)}; // I don't want to rebuild this value for every date cell in the table private static long EpochTicks = new DateTime(1970, 1, 1).Ticks; private static string JSONValueFromDataRowObject(object value, Type DataType) { // null if (value == DBNull.Value) return "null"; // numeric if (Array.IndexOf(numeric, DataType) > -1) return value.ToString(); // TODO: eventually want to use a stricter format // boolean if (DataType == typeof(bool)) return ((bool)value) ? "true" : "false"; // date -- see http://weblogs.asp.net/bleroy/archive/2008/01/18/dates-and-json.aspx if (DataType == typeof(DateTime)) return "\"\\/Date(" + new TimeSpan(((DateTime)value).ToUniversalTime().Ticks - EpochTicks).TotalMilliseconds.ToString() + ")\\/\""; // TODO: add Timespan support // TODO: add Byte[] support //TODO: this would be _much_ faster with a state machine // string/char return "\"" + value.ToString().Replace(@"\", @"\\").Replace(Environment.NewLine, @"\n").Replace("\"", @"\""") + "\""; } }

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  • Good 2D Platformer Physics

    - by Joe Wreschnig
    I have a basic character controller set up for a 2D platformer with Box2D, and I'm starting to tweak it to try to make it feel good. Physics engines have a lot of knobs to tweak, and it's not clear to me, writing with a physics engine for the first time, which ones I should use. Should jumping apply a force for several ticks? An impulse? Directly set velocity? How do I stop the avatar from sticking to walls without taking away all its friction (or do I take away all the friction, but only in the air)? Should I model the character as a capsule? A box with rounded corners? A box with two wheels? Just one big wheel? I feel like someone must have done this before! There seem to be very few resources available on the web that are not "baby's first physics", which all cut off where I'm hoping someone has already solved the issues. Most examples of physics engines for platformers have floaty-feeling controls, or in-air jumps, or easily exploitable behavior when temporary penetration is too high, etc. Some examples of what I mean: A short tap of jump jumps a short distance; a long tap jumps higher. Short skidding when stopping or reversing directions at high velocity. Standing stably on inclines (but maybe sliding down them when ducking). Analog speed when using an analog controller. All the other things that separate good platformers from bad platformers. Dare I suggest, stable moving platforms? I'm not really looking for "hey, do this." Obviously, the right thing to do is dependent on what I want in the game. But I'm hoping someone somewhere has gone through the possibilities and said "well technique A does feature X well, technique B does Y well, but that doesn't work with C", or has some worked examples beyond "if (key == space) character.impulse(0, 1)"

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  • MySQL - Configuration

    - by Stuart Brierley
    Having previously detailed how to install MySQL Server, the next step is configuring MySQL. The MySQL configuration wizard can either be run immediately following installation from the MySQL installation wizard or manually from the Start Menu. Following the splash screen you can then choose whether to run a detailed or standard configuration. The detailed configuration allows you to create the optimal configuration for your specific machine, whereas the standard configuration creates a general configuration that can then be manually tuned. I chose detailed.   You are then asked to choose the type of server instance that is being configured. In this case it is a developer machine. Following this you are asked to choose the type of database usage that you expect on the server. I opted for multifunctional. You must then specify the location of the InnoDB tablespace.   Next specify the number of concurent connections to the server.   Now you must configure the networking options. I left the Strict mode enabled as this is the recommended option, but I disabled TCP/IP networking as I wanted to restrict this MySQL installation to the local machine only.   Set the character set that is best suited to your use - for me this was the default standard character set. Next up is the option to run MySQL as a service and whether or not to include the mysql dircetories in the windows PATH. I kept the install as a windows service option enabled, but unchecked the Launch MySQL server automatically option. This is because I only wanted MySQL running when I specifically want to use it. I also enabled the include in windows PATH option.   You can then change the security settings for the mysql installation. I opted to change the root password, disable root from local machines and disable annoymous access.   You are now ready to execute the configuration.   Once completed you should hopefully see the completed screen with lots of nice ticks against the various configuration tasks.

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  • Architecture of an action multiplayer game from scratch

    - by lcf
    Not sure whether it's a good place to ask (do point me to a better one if it's not), but since what we're developing is a game - here it goes. So this is a "real-time" action multiplayer game. I have familiarized myself with concepts like lag compensation, view interpolation, input prediction and pretty much everything that I need for this. I have also prepared a set of prototypes to confirm that I understood everything correctly. My question is about the situation when game engine must be rewind to the past to find out whether there was a "hit" (sometimes it may involve the whole 'recomputation' of the world from that moment in the past up to the present moment. I already have a piece of code that does it, but it's not as neat as I need it to be. The domain logic of the app (the physics of the game) must be separated from the presentation (render) and infrastructure tools (e.g. the remote server interaction specifics). How do I organize all this? :) Is there any worthy implementation with open sources I can take a look at? What I'm thinking is something like this: -> Render / User Input -> Game Engine (this is the so called service layer) -> Processing User Commands & Remote Server -> Domain (Physics) How would you add into this scheme the concept of "ticks" or "interactions" with the possibility to rewind and recalculate "the game"? Remember, I cannot change the Domain/Physics but only the Game Engine. Should I store an array of "World's States"? Should they be just some representations of the world, optimized for this purpose somehow (how?) or should they be actual instances of the world (i.e. including behavior and all that). Has anybody had similar experience? (never worked on a game before if that matters)

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