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• How can I store this kind of graph in neo4j for fast traversal?

  - by James

  This is a graph whose nodes exist in many connected components at once because a node's relationships are a collection of edge groups such that only one edge per edge group can be present at once. I need to be able to find all of the connected components that a node exists in. What would be the best way to store this graph in neo4j to quickly find all of the connected components that a node exists in? Is there a way to use the built in traversals to do this? Also: is there a name for this kind of graph? I'd appreciate any help/ideas. Update: Sorry for not being clear. All nodes are of the same type. Nodes have a variable number of edge groups. Exactly one edge from each edge group needs to be chosen for a particular connected component. I'm going to try to explain through example: Node x1 is related to: (x2 or x3 or x4) AND (x5 or x6) AND (x7) Node x2 is related to: (x8) AND (x9 or x10) So x1's first edge group is (x2, x3, x4), its second edge group is (x5, x6), and its third edge group is (x7). So here are a few connected components that x1 exists in: CC1: x1 is related to: x2, x5, x7 x2 is related to: x8 x9 CC2: x1 is related to: x2, x6, x7 x2 is related to: x8, x9 CC3: x1 is related to: x3, x5, x7 CC4: x1 is related to: x3, x6, x7 etc. I'm grateful for your help in this.

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• Prevent hash navigation url

  - by Koningh

  I have the following problem: I'm using a slider (coda) to let people navigate trough some 'pages'. The slider uses hash links to navigate to the next page/slide. If a user is at page one (#page1), there is a link which will lead the user to page 2 (#page2) and so on. At the top of the slider the numbers of the pages appear as a link, but only when the page is visited. So if there are six pages and the user navigates from the first to the second and then the third one, there are only three links at the top of the slider (to page one, two and three). The problem is that a user can navigate to page five (or any page actually) without first visiting the pages previous to page five by just using the hash URL and typing the whole link in their address bar. For example if I would type www.mydomain.com/slider/index.php#page5 the slider automatically navigates to the fifth slide/page of the slider and thereby skipping the first four. I want to allow users to navigate to #page5 only if they have visited the first four (So by clicking trough the slides). This means that if they would go to #page5 directly by typing the URL in the address bar, I would like them to be send to the first page (#page1). Does anyone have any idea on solving this?

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• Stored Procedure: Reducing Table Data

  - by SumGuy

  Hi Guys, A simple question about Stored Procedures. I have one stored procedure collecting a whole bunch of data in a table. I then call this procedure from within another stored procedure. I can copy the data into a new table created in the calling procedure but as far as I can see the tables have to be identical. Is this right? Or is there a way to insert only the data I want? For example.... I have one procedure which returns this: SELECT @batch as Batch, @Count as Qty, pd.Location, cast(pd.GL as decimal(10,3)) as [Length], cast(pd.GW as decimal(10,3)) as Width, cast(pd.GT as decimal(10,3)) as Thickness FROM propertydata pd GROUP BY pd.Location, pd.GL, pd.GW, pd.GT I then call this procedure but only want the following data: DECLARE @BatchTable TABLE ( Batch varchar(50), [Length] decimal(10,3), Width decimal(10,3), Thickness decimal(10,3), ) INSERT @BatchTable (Batch, [Length], Width, Thickness) EXEC dbo.batch_drawings_NEW @batch So in the second command I don't want the Qty and Location values. However the code above keeps returning the error: "Insert Error: Column name or number of supplied values does not match table"

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• What's the correct way to pass parameters from VBScript to COM interface implemented in C#?

  - by nopopem

  I'm trying to expose a fairly simple C# class to COM which should be usable from VBScript (among others). Some objects need to be created via COM calls and will be used in furter calls later on. The definition of the exposed classes and interfaces looks like this: namespace Test { [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)] public interface IComInterface { IFoo CreateFoo(); void UseFoo(int x, IFoo f); } [ClassInterface(ClassInterfaceType.None)] public sealed class CComInterface : IComInterface { public CComInterface() {} public IFoo CreateFoo() { return new Foo(); } public void UseFoo(int x, IFoo f) { f.Bar(); } } [InterfaceType(ComInterfaceType.InterfaceIsIDispatch)] public interface IFoo { void Bar(); } [ClassInterface(ClassInterfaceType.None)] public class Foo : IFoo { internal Foo() {} public void Bar() {} } } The simplest thinkable COM client in VBScript does this: Dim ci Set ci = WScript.CreateObject("Test.CComInterface") Dim foo Set foo = ci.CreateFoo foo.Bar ci.UseFoo 0, foo While the call to Bar succeeds, calling UseFoo fails with "Error 5: invalid procedure call or invalid argument" The generated IDL seems ok to me: dispinterface IComInterface { properties: methods: [id(0x60020003)] IFoo* CreateFoo(); [id(0x60020004)] void UseFoo( [in] long x, [in] IFoo* f); }; The vbs call succeeds when I wrap the second parameter in parentheses like this: ci.UseFoo 0, (foo) As far as I understand (I'm no VBScript expert however) this forces the reference to foo to be passed by value, i.e. a copy of the reference is being made. How can I change the interface so that it can be called with the foo reference directly? Since this will be a public interface used by customers I don't like the idea of having to explain why all the objects created need to be passed back in an extra pair of parentheses...

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• What was your "aha moment" in understanding delegates?

  - by CM90

  Considering the use of delegates in C#, does anyone know if there is a performance advantage or if it is a convenience to the programmer? If we are creating an object that holds a method, it sounds as if that object would be a constant in memory to be called on, instead of loading the method every time it is called. For example, if we look at the following Unity3D-based code: public delegate H MixedTypeDelegate<G, H>(G g) public class MainParent : MonoBehaviour // Most Unity classes inherit from M.B. { public static Vector3 getPosition(GameObject g) { /* GameObject is a Unity class, and Vector3 is a struct from M.B. The "position" component of a GameObject is a Vector3. This method takes the GameObject I pass to it & returns its position. */ return g.transform.position; } public static MixedTypeDelegate<GameObject, Vector3> PositionOf; void Awake( ) // Awake is the first method called in Unity, always. { PositionOf = MixedTypeDelegate<GameObject, Vector3>(getPosition); } } public class GameScript : MainParent { GameObject g = new GameObject( ); Vector3 whereAmI; void Update( ) { // Now I can say: whereAmI = PositionOf(g); // Instead of: whereAmI = getPosition(g); } } . . . But that seems like an extra step - unless there's that extra little thing that it helps. I suppose the most succinct way to ask a second question would be to say: When you had your aha moment in understanding delegates, what was the context/scenario/source? Thank you!

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• Best practices for encrytping continuous/small UDP data

  - by temp

  Hello everyone, I am having an application where I have to send several small data per second through the network using UDP. The application need to send the data in real-time (on waiting). I want to encrypt these data and insure that what I am doing is as secure as possible. Since I am using UDP, there is no way to use SSL/TLS, so I have to encrypt each packet alone since the protocol is connectionless/unreliable/unregulated. Right now, I am using a 128-bit key derived from a passphrase from the user, and AES in CBC mode (PBE using AES-CBC). I decided to use a random salt with the passphrase to derive the 128-bit key (prevent dictionary attack on the passphrase), and of course use IVs (to prevent statistical analysis for packets). However I am concerned about few things: Each packet contains small amount of data (like a couple of integer values per packet) which will make the encrypted packets vulnerable to known-plaintext attacks (which will result in making it easier to crack the key). Also, since the encryption key is derived from a passphrase, this will make the key space way less (I know the salt will help, but I have to send the salt through the network once and anyone can get it). Given these two things, anyone can sniff and store the sent data, and try to crack the key. Although this process might take some time, once the key is cracked all the stored data will be decrypted, which will be a real problem for my application. So my question is, what is the best practices for sending/encrypting continuous small data using a connectionless protocol (UDP)? Is my way the best way to do it? ...flowed? ...Overkill? ... Please note that I am not asking for a 100% secure solution, as there is no such thing. Cheers

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• recvfrom returns invalid argument when *from* is passed

  - by Aditya Sehgal

  I am currently writing a small UDP server program in linux. The UDP server will receive packets from two different peers and will perform different operations based on from which peer it received the packet. I am trying to determine the source from where I receive the packet. However, when select returns and recvfrom is called, it returns with an error of Invalid Argument. If I pass NULL as the second last arguments, recvfrom succeeds. I have tried declaring fromAddr as struct sockaddr_storage, struct sockaddr_in, struct sockaddr without any success. Is their something wrong with this code? Is this the correct way to determine the source of the packet? The code snippet follows. ` /*TODO : update for TCP. use recv */ if((pkInfo->rcvLen=recvfrom(psInfo->sockFd, pkInfo->buffer, MAX_PKTSZ, 0, /* (struct sockaddr*)&fromAddr,*/ NULL, &(addrLen) )) < 0) { perror("RecvFrom failed\n"); } else { /*Apply Filter */ #if 0 struct sockaddr_in* tmpAddr; tmpAddr = (struct sockaddr_in* )&fromAddr; printf("Received Msg From %s\n",inet_ntoa(tmpAddr->sin_addr)); #endif printf("Packet Received of len = %d\n",pkInfo->rcvLen); } `

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• Interval arithmetic to correctly deal with end of month - Oracle SQL

  - by user2003974

  I need a function which will do interval arithmetic, dealing "correctly" with the different number of days in a month. For my version of "correctly" - see below! First try select to_date('31-May-2014') + interval '1' months from dual This returns an error, because there is no 31st June. I understand that this behaviour is expected due to the ANSI standard. Second try select add_months(to_date('31-May-2014'),1) from dual This correctly (in my use case) returns 30th June 2014, which is great. BUT select add_months(to_date('28-Feb-2014'),1) from dual returns 31st March 2014, when I want 28th March 2014. Background This has to do with legal deadlines. The deadlines are expressed in law as a number of months (say, 3) from a base date. If the base date is last day of the month and three months later the month is longer, then the deadline does NOT extend to the end of the longer month (as per the add_months function). However, if the base date is last day of the month and three months later the month is shorter, then the deadline expires on the last day of the shorter month. Question Is there a function that does what I need? I have intervals (year to month) stored in a table, so preferably the function would look like: add_interval_correctly(basedate DATE, intervaltoadd INTERVAL YEAR TO MONTH)

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• ADO.NET Data Services Media type requires a ';' character before a parameter definition.

  - by idahosaedokpayi

  I am experimenting with ADO.NET and I am seeing this error on the second attempt to browse the service: <?xml version="1.0" encoding="utf-8" standalone="yes" ?> <error xmlns="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata"> <code /> <message xml:lang="en-US">Media type requires a ';' character before a parameter definition.</message> </error> The first attempt is normal. I am working with an exactly identical service on an internal development network and it is fine. I am including my connection string: <add name="J4Entities" connectionString="metadata=res://*;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=MNSTSQL01N;Initial Catalog=J4;Integrated Security=True;MultipleActiveResultSets=True&quot;" providerName="System.Data.EntityClient"/> and my Data service class: using System; using System.Data.Services; using System.Collections.Generic; using System.Linq; using System.ServiceModel.Web; public class Data : DataService< J4Model.J4Entities > { // This method is called only once to initialize service-wide policies. public static void InitializeService(IDataServiceConfiguration config) { // TODO: set rules to indicate which entity sets and service operations are visible, updatable, etc. // Examples: config.SetEntitySetAccessRule("*", EntitySetRights.AllRead); // config.SetServiceOperationAccessRule("MyServiceOperation", ServiceOperationRights.All); } } Is there something obvious I am not doing?

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• Why is CoRegisterClassObject creating two extra threads?

  - by Stijn Sanders

  I'm trying to fix a problem that only recently happens on a number of machine's on a VPN. They each run a client application I wrote that exposes a COM automation object. For some strange reason I haven't been able to discover yet, one thread in the application takes up all of the available CPU time, slowing other operation on the machine. In observing the application's strange behaviour, I've noticed it's the third thread started, and if I debug on my machine I notice the first call to CoRegisterClassObject created two extra threads. If the second of these two threads is the one that gets into an infinite loop, I'm not at all shure how to fix this. Where could I check next about what's wrong? Could it have started by one of the recent patches rolled out by Microsoft this last 'patch tuesday'? I had a go with ProcessExplorer to extract a stack trace of the thread: ntoskrnl.exe!ExReleaseResourceLite+0x1a3 ntoskrnl.exe!PsGetContextThread+0x329 WLDAP32.dll!Ordinal325+0x1231 WLDAP32.dll!Ordinal325+0x129e WLDAP32.dll!Ordinal325+0x1178 ntdll.dll!LdrInitializeThunk+0x24 ntdll.dll!LdrShutdownThread+0xe9 kernel32.dll!ExitThread+0x3e kernel32.dll!FreeLibraryAndExitThread+0x1e ole32.dll!StringFromGUID2+0x65d kernel32.dll!GetModuleFileNameA+0x1ba

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• Can I use drawRect to refresh a UIView subclass?

  - by Timbo

  I've created a subclass of UIView called Status which is designed to display a rectangle of a certain size (within a view) depending on the value of a variable. // Interface #import <Foundation/Foundation.h> #import <QuartzCore/QuartzCore.h> @interface Status: UIView { NSString* name; int someVariable; } @property int someVariable; @property (assign) NSString *name; - (void) createStatus: (NSString*)withName; - (void) drawRect:(CGRect)rect; @end // Implementation #import "Status.h" @implementation Status @synthesize name, someVariable; - (void) createStatus: (NSString*)withName { name = withName; someVariable = 10000; } - (void) drawRect:(CGRect)rect { CGContextRef context = UIGraphicsGetCurrentContext(); //Draw Status CGContextSetRGBFillColor(context, 0.0, 0.0, 1.0, 1); // fill CGContextFillRect(context, CGRectMake(0.0, 0.0, someVariable, 40.0)); } //// myviewcontroller implementation - (void) viewDidAppear:(BOOL)animated { [super viewDidAppear:animated]; myStatus = [[Status alloc] initWithFrame:CGRectMake(8,8,200,56)]; myStatus.backgroundColor = [UIColor grayColor]; [self.view addSubview:myStatus]; } How do I set this up so I can repeatedly call a refresh of the status bar? I'll probably call the refresh 4 times per second using a NSTimer, I'm just not sure what to call or if I should move this rectangle drawing to a separate function or something... Thanks in advance for your help :)

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• For-Loop and LINQ's deferred execution don't play well together

  - by Tim Schmelter

  The title suggests that i've already an idea what's going on, but i cannot explain it. I've tried to order a List<string[]> dynamically by each "column", beginning with the first and ending with the minimum Length of all arrays. So in this sample it is 2, because the last string[] has only two elements: List<string[]> someValues = new List<string[]>(); someValues.Add(new[] { "c", "3", "b" }); someValues.Add(new[] { "a", "1", "d" }); someValues.Add(new[] { "d", "4", "a" }); someValues.Add(new[] { "b", "2" }); Now i've tried to order all by the first and second column. I could do it statically in this way: someValues = someValues .OrderBy(t => t[0]) .ThenBy(t => t[1]) .ToList(); But if i don't know the number of "columns" i could use this loop(that's what I thought): int minDim = someValues.Min(t => t.GetLength(0)); // 2 IOrderedEnumerable<string[]> orderedValues = someValues.OrderBy(t => t[0]); for (int i = 1; i < minDim; i++) { orderedValues = orderedValues.ThenBy(t => t[i]); } someValues = orderedValues.ToList(); // IndexOutOfRangeException But that doesn't work, it fails with an IndexOutOfRangeException at the last line. The debugger tells me that i is 2 at that time, so the for-loop condition seems to be ignored, i is already == minDim. Why is that so?

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• What changed in the DataGrid that means it won't work anymore?

  - by Jeff Yates

  I have a Silverlight app with a DataGrid containing some custom columns and all was working well. Then I updated to Silverlight 3 tools for VS 2008 SP1 and rebuilt it. Now it has the following problems: Rows aren't added when the collection is modified. The ItemsSource property is (and always has been) set to an ObservableCollection instance, which notifies when its contents change. This worked fine for Silverlight 2. However, in Silverlight 3 to get this working at all, I now have to null and then re-set ItemsSource - this seems like I'm hiding a bigger issue but I can't work out what that might be. I cannot select a row or a cell anymore. If I'm lucky, I can select one whole row before it stops working. I can't edit anything. I suspect this is related to the previous point. I'll post some source when I am able, but first I have to strip it down to the bare minimum. In the meantime, I was hoping someone might have some idea of what may be going on here. My gut feeling on the second two points is that my bindings are no longer working, but that's just a guess and if it is the case, I have no idea which ones. Thanks for any help anyone might be able to provide. Update So, I finally reduced my problem down to a simple works/doesn't work comparison. The problem seems to occur if I override Equals in my element type. As soon as I do that, something happens strangely in the ObservableCollection that contains that type, it seems, and my application breaks. To make it more interesting, there is a check to make sure that duplicate items don't even get close to being added to the collection. I don't exactly know why ObservableCollection needs to compare equality when inserting items (the stack trace indicates it is using IndexAt) but this seems to cause the issue. So, any thoughts?

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• vba: what does ReDim Preserve do and simple array question

  - by every_answer_gets_a_point

  i am looking at someone else's vba excel code. they are doing ReDim Preserve dataMatrix(7, i) in both loops. what does this do? also, it seems like the second loop just overwrites the data in the first, loop, is that correct? Dim dataMatrix() As String Worksheets.Item("ETS").Select Do While Trim(Cells(r, 1)) <> "" Debug.Print "The line: ", Trim(Cells(r, 1)), r r = r + 1 dataMatrix(1, i) = Trim(Cells(r, 1)) ''file name dataMatrix(2, i) = Trim(Cells(r, 2)) ''sample type dataMatrix(3, i) = Trim(Cells(r, 3)) ''sample name dataMatrix(4, i) = "ETS" '' dataMatrix(5, i) = Trim(Cells(r, 5)) ''Response dataMatrix(6, i) = Trim(Cells(r, 6)) ''ISTD Response dataMatrix(7, i) = Trim(Cells(r, 10)) ''Calculated Conc i = i + 1 ReDim Preserve dataMatrix(7, i) Loop r = 5 Worksheets.Item("ETG").Select Do While Trim(Cells(r, 1)) <> "" Debug.Print "The line: ", Trim(Cells(r, 1)), r r = r + 1 dataMatrix(1, i) = Trim(Cells(r, 1)) ''file name dataMatrix(2, i) = Trim(Cells(r, 2)) ''sample type dataMatrix(3, i) = Trim(Cells(r, 3)) ''sample name dataMatrix(4, i) = "ETG" dataMatrix(5, i) = Trim(Cells(r, 5)) ''Response dataMatrix(6, i) = Trim(Cells(r, 6)) ''ISTD Response dataMatrix(7, i) = Trim(Cells(r, 10)) ''Calculated Conc i = i + 1 ReDim Preserve dataMatrix(7, i) Loop

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• C++ design related question

  - by Kotti

  Hi! Here is the question's plot: suppose I have some abstract classes for objects, let's call it Object. It's definition would include 2D position and dimensions. Let it also have some virtual void Render(Backend& backend) const = 0 method used for rendering. Now I specialize my inheritance tree and add Rectangle and Ellipse class. Guess they won't have their own properties, but they will have their own virtual void Render method. Let's say I implemented these methods, so that Render for Rectangle actually draws some rectangle, and the same for ellipse. Now, I add some object called Plane, which is defined as class Plane : public Rectangle and has a private member of std::vector<Object*> plane_objects; Right after that I add a method to add some object to my plane. And here comes the question. If I design this method as void AddObject(Object& object) I would face trouble like I won't be able to call virtual functions, because I would have to do something like plane_objects.push_back(new Object(object)); and this should be push_back(new Rectangle(object)) for rectangles and new Circle(...) for circles. If I implement this method as void AddObject(Object* object), it looks good, but then somewhere else this means making call like plane.AddObject(new Rectangle(params)); and this is generally a mess because then it's not clear which part of my program should free the allocated memory. ["when destroying the plane? why? are we sure that calls to AddObject were only done as AddObject(new something).] I guess the problems caused by using the second approach could be solved using smart pointers, but I am sure there have to be something better. Any ideas?

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• VBA does not run Powerpoint

  - by user1557188

  This is very frustrating, first lines of programming Powerpoint VBA after a long while .... Please help this is killing me Writing a small sub connecting to an action using name test Sub test() MSGBOX "this is a test " end sub I placed this in a module I just created and it works I copy the same test in named as a module and it does not work any more .... I'm trying to make PPT connect to events to do things on a per slide basis ..... using google.... this worked a few times ... but now nothing works any more. The simple test above fails since I renamed the module. As I further change the second routine to test1() ipv test None of the macros can be executed any more (module1 NOT CHNANGED) Module NAME..... contains the same code, except test1() ipv test. ... now all macro processing stops the color of text changes (as is clicked on it) but nothing gets obviously executed. Are things that unstable recenty in VBA for powerpoint 2010 how did I run: connect to empty slide using 3 lines test 1 test 2 test 3 on each of the lines I defined an action for each in different modules run: Go into slide show and on the first slide just click.... color changes but nothing happens any more Saved all closed restarted .... simply refuses except on first created pptm

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• My IF statement is changing variables in PHP

  - by user1902509

  I am fairly new to the whole programming thing, so forgive me if this is a stupid question. It seems odd that I haven't run into it before. I am trying to make an order form for a cake. You fill out the form, submit it, and it will then display the order in a new window, where you then hit "submit," and upload it to the Database. I have a series of If Statements to check for errors in the form before submitting it. Here is a simplified version of the code. Writing means any writing you want on the cake, Name is your name, and cake is what type of cake you want (the default is "None"). try { $name = trim($params->name); $cake = trim($params->cake); $writing = trim($params->writing); if (strlen($name) < 3){ throw new Exception("Please enter Your name."); } if ($cake = "None") { throw new Exception("Please select a Cake" } if ($cake = "Caramel Apple Pie" or $cake = "Pumpkin Pie" or $cake = "Eggnog Pie" and strlen($writing) > 1) { throw new Exception("We are sorry, but you can't write on any of our specialty pies."); } } catch(Exception $x) { $error = $x->getmessage(); } So what is happening is that when I go and hit submit the first time, the correct cake type comes up, but when you submit it the second time, the error comes up saying that I have "None" selected. All the other values are there and remain the same. I think the problem is that the first "IF" statement (Where it says "If($cake = "None")) is automatically changing $cake to "None" because I have tried commenting just that statement out, and it will then change the cake to be "Caramel Apple Pie," which is in the top of the next IF statement. Anyone know why it is doing this? And how to fix it?

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• Weird characters at the beginning of a LPTSTR? C++

  - by extintor

  I am using this code to get the windows version: define BUFSIZE 256 bool config::GetOS(LPTSTR OSv) { OSVERSIONINFOEX osve; BOOL bOsVersionInfoEx; ZeroMemory(&osve, sizeof(OSVERSIONINFOEX)); osve.dwOSVersionInfoSize = sizeof(OSVERSIONINFOEX); if( !(bOsVersionInfoEx = GetVersionEx ((OSVERSIONINFO *) &osve)) ) return false; TCHAR buf[BUFSIZE]; StringCchPrintf(buf, BUFSIZE, TEXT("%u.%u.%u.%u"), osve.dwPlatformId, osve.dwMajorVersion, osve.dwMinorVersion, osve.dwBuildNumber); StringCchCat(OSv, BUFSIZE, buf); return true; } And I am testing it with: LPTSTR OSv= new TCHAR[BUFSIZE]; config c; c.GetOS(OSv); MessageBox(OSv, 0, 0); And in the msgbox I get something like this äì5.1.20 (where 5.1.20 is = to OSv) but the first 2 or 3 chars are some weird characters that I don't know when they came from. Even stranger, if I call that second piece again it shows it ok, it only show the weird characters the first time I execute it. Does someone has an idea what's going on here?

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• Unit Testing - Algorithm or Sample based ?

  - by ohadsc

  Say I'm trying to test a simple Set class public IntSet : IEnumerable<int> { Add(int i) {...} //IEnumerable implementation... } And suppose I'm trying to test that no duplicate values can exist in the set. My first option is to insert some sample data into the set, and test for duplicates using my knowledge of the data I used, for example: //OPTION 1 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //3 will be added 3 times var values = new List<int> {1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I know 3 is the only candidate to appear multiple times int counter = 0; foreach (int i in set) if (i == 3) counter++; Assert.AreEqual(1, counter); } My second option is to test for my condition generically: //OPTION 2 void InsertDuplicateValues_OnlyOneInstancePerValueShouldBeInTheSet() { var set = new IntSet(); //The following could even be a list of random numbers with a duplicate var values = new List<int> { 1, 2, 3, 3, 3, 4, 5}; foreach (int i in values) set.Add(i); //I am not using my prior knowledge of the sample data //the following line would work for any data CollectionAssert.AreEquivalent(new HashSet<int>(values), set); } Of course, in this example, I conveniently have a set implementation to check against, as well as code to compare collections (CollectionAssert). But what if I didn't have either ? This is the situation when you are testing your real life custom business logic. Granted, testing for expected conditions generically covers more cases - but it becomes very similar to implementing the logic again (which is both tedious and useless - you can't use the same code to check itself!). Basically I'm asking whether my tests should look like "insert 1, 2, 3 then check something about 3" or "insert 1, 2, 3 and check for something in general" EDIT - To help me understand, please state in your answer if you prefer OPTION 1 or OPTION 2 (or neither, or that it depends on the case, etc )

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• Android: Scheduling application to start with repeating alarms not working

  - by vikramagain

  I get my Broadcast receiver to set a recurring alarm, to fire up a service. Unfortunately this does not result in the service being called repeatedly (based on logcat). I've experimented with different values for the time interval too. Can someone help? (I'm testing through Eclipse on Android 3.2 Motorola xoom) Below is the code for the Broadcast receiver. alarm = (AlarmManager) arg0.getSystemService(Context.ALARM_SERVICE); Intent intentUploadService = new Intent (arg0, com.vikramdhunta.UploaderService.class); Calendar calendar = Calendar.getInstance(); calendar.setTimeInMillis(System.currentTimeMillis()); calendar.add(Calendar.SECOND, 3); PendingIntent pi = PendingIntent.getBroadcast(arg0, 0, intentUploadService , 0); alarm.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), 5, pi); Below is the code for the Service class public UploaderService() { super("UploaderService"); mycounterid = globalcounter++; } @Override protected void onHandleIntent(Intent intent) { synchronized(this) { try { for (int i = 1;i < 5;i++) { // doesn't do much right now.. but this should appear in logcat Log.i(TAG,"OK " + globalcounter++ + " uploading..." + System.currentTimeMillis()); } } catch(Exception e) { } } } @Override public void onCreate() { super.onCreate(); Log.d("TAG", "Service created."); } @Override public IBinder onBind(Intent arg0) { return null; } @Override public int onStartCommand(Intent intent, int flags, int startId) { Log.i(TAG, "Starting upload service..." + mycounterid); return super.onStartCommand(intent,flags,startId); }

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• How long is the time frame between context switches on Windows?

  - by mattcodes

  Reading CLR via C# 2.0 (I dont have 3.0 with me at the moment) Is this still the case: If there is only one CPU in a computer, only one thread can run at any one time. Windows has to keep track of the thread objects, and every so often, Windows has to decide which thread to schedule next to go to the CPU. This is additional code that has to execute once every 20 milliseconds or so. When Windows makes a CPU stop executing one thread's code and start executing another thread's code, we call this a context switch. A context switch is fairly expensive because the operating system has to: So circa CLR via C# 2.0 lets say we are on Pentium 4 2.4ghz 1 core non-HT, XP. Every 20 milliseconds? Where a CLR thread or Java thread is mapped to an OS thread only a maximum of 50 threads per second may get a chance to to run? I've read that context switching is very fast in mircoseconds here on SO, but how often roughly (magnitude style guesses) will say a modest 5 year old server Windows 2003 Pentium Xeon single core give the OS the opportunity to context switch? 20ms in the right area? I dont need exact figures I just want to be sure that's in the right area, seems rather long to me.

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• Is there a reason why SSIS significantly slows down after a few minutes?

  - by Mark

  I'm running a fairly substantial SSIS package against SQL 2008 - and I'm getting the same results both in my dev environment (Win7-x64 + SQL-x64-Developer) and the production environment (Server 2008 x64 + SQL Std x64). The symptom is that initial data loading screams at between 50K - 500K records per second, but after a few minutes the speed drops off dramatically and eventually crawls embarrasingly slowly. The database is in Simple recovery model, the target tables are empty, and all of the prerequisites for minimally logged bulk inserts are being met. The data flow is a simple load from a RAW input file to a schema-matched table (i.e. no complex transforms of data, no sorting, no lookups, no SCDs, etc.) The problem has the following qualities and resiliences: Problem persists no matter what the target table is. RAM usage is lowish (45%) - there's plenty of spare RAM available for SSIS buffers or SQL Server to use. Perfmon shows buffers are not spooling, disk response times are normal, disk availability is high. CPU usage is low (hovers around 25% shared between sqlserver.exe and DtsDebugHost.exe) Disk activity primarily on TempDB.mdf, but I/O is very low (< 600 Kb/s) OLE DB destination and SQL Server Destination both exhibit this problem. To sum it up, I expect either disk, CPU or RAM to be exhausted before the package slows down, but instead its as if the SSIS package is taking an afternoon nap. SQL server remains responsive to other queries, and I can't find any performance counters or logged events that betray the cause of the problem. I'll gratefully reward any reasonable answers / suggestions.

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• Serialization of Queue type not working

  - by Soham

  Consider this piece of code: private Queue Date=new Queue(); //other declarations public DateTime _Date { get { return (DateTime)Date.Peek();} set { Date.Enqueue(value); } } //other properties and stuff.... public void UpdatePosition(...) { //other code IFormatter formatter = new BinaryFormatter(); Stream Datestream = new MemoryStream(); formatter.Serialize(Datestream, Date); byte[] Datebin = new byte[2048]; Datestream.Read(Datebin,0,2048); //Debug-Bug Console.WriteLine(Convert.ToString(this._Date)); Console.WriteLine(BitConverter.ToString(Datebin, 0, 3)); //other code } The output of the first WriteLine is perfect. I.e to check if really the Queue is initialised or not. It is. The right variables are stored etc. (I inserted a value in that Queue, that part of the code is not shown.) But the second WriteLine is not giving the right expected answer: It serializes the entire Queue to 00-00-00.

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• Cache layer for MVC - Model or controller?

  - by Industrial

  Hi everyone, I am having some second thoughts about where to implement the caching part. Where is the most appropriate place to implement it, you think? Inside every model, or in the controller? Approach 1 (psuedo-code): // mycontroller.php MyController extends Controller_class { function index () { $data = $this->model->getData(); echo $data; } } // myModel.php MyModel extends Model_Class{ function getData() { $data = memcached->get('data'); if (!$data) { $query->SQL_QUERY("Do query!"); } return $data; } } Approach 2: // mycontroller.php MyController extends Controller_class { function index () { $dataArray = $this->memcached->getMulti('data','data2'); foreach ($dataArray as $key) { if (!$key) { $data = $this->model->getData(); $this->memcached->set($key, $data); } } echo $data; } } // myModel.php MyModel extends Model_Class{ function getData() { $query->SQL_QUERY("Do query!"); return $data; } } Thoughts: Approach 1: No multiget/multi-set. If a high number of keys would be returned, overhead would be caused. Easier to maintain, all database/cache handling is in each model Approach 2: Better performancewise - multiset/multiget is used More code required Harder to maintain Tell me what you think!

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• How expensive is a context switch? Is it better to implement a manual task switch than to rely on OS

  - by Vilx-

  The title says it all. Imagine I have two (three, four, whatever) tasks that have to run in parallel. Now, the easy way to do this would be to create separate threads and forget about it. But on a plain old single-core CPU that would mean a lot of context switching - and we all know that context switching is big, bad, slow, and generally simply Evil. It should be avoided, right? On that note, if I'm writing the software from ground up anyway, I could go the extra mile and implement my own task-switching. Split each task in parts, save the state inbetween, and then switch among them within a single thread. Or, if I detect that there are multiple CPU cores, I could just give each task to a separate thread and all would be well. The second solution does have the advantage of adapting to the number of available CPU cores, but will the manual task-switch really be faster than the one in the OS core? Especially if I'm trying to make the whole thing generic with a TaskManager and an ITask, etc?

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