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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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DTGridView losing content while scrolling

- by Wim Haanstra

I am using DTGridView from the DTKit by Daniel Tull. I implemented it in a very simple ViewController and the test I am doing is to place a button in the last row of the grid, which should add another row to the grid (and therefor moving the button to a row beneath it). The problem is, when I click the button a couple of times and then start scrolling, the grid seems to lose its content. As I am not completly sure this is a bug in the grid, but more in my code, I hope you guys can help me out and track down the bug. First I have my header file, which is quite simple, because this is a test: #import <UIKit/UIKit.h> #import "DTGridView.h" @interface TestController : UIViewController <DTGridViewDelegate, DTGridViewDataSource> { DTGridView* thumbGrid; } @end I declare a DTGridView, which will be my grid, where I want to put content in. Now, my code file: #import "TestController.h" @implementation TestController int rows = 1; - (NSInteger)numberOfRowsInGridView:(DTGridView *)gridView { return rows; } - (NSInteger)numberOfColumnsInGridView:(DTGridView *)gridView forRowWithIndex:(NSInteger)index { if (index == rows - 1) return 1; else return 3; } - (CGFloat)gridView:(DTGridView *)gridView heightForRow:(NSInteger)rowIndex { return 57.0f; } - (CGFloat)gridView:(DTGridView *)gridView widthForCellAtRow:(NSInteger)rowIndex column:(NSInteger)columnIndex { if (rowIndex == rows - 1) return 320.0f; else return 106.6f; } - (DTGridViewCell *)gridView:(DTGridView *)gridView viewForRow:(NSInteger)rowIndex column:(NSInteger)columnIndex { DTGridViewCell *view = [[gridView dequeueReusableCellWithIdentifier:@"thumbcell"] retain]; if (!view) view = [[DTGridViewCell alloc] initWithReuseIdentifier:@"thumbcell"]; if (rowIndex == rows - 1) { UIButton* btnLoadMoreItem = [[UIButton alloc] initWithFrame:CGRectMake(10, 0, 301, 57)]; [btnLoadMoreItem setTitle:[NSString stringWithFormat:@"Button %d", rowIndex] forState:UIControlStateNormal]; [btnLoadMoreItem.titleLabel setFont:[UIFont boldSystemFontOfSize:20]]; [btnLoadMoreItem setBackgroundImage:[[UIImage imageNamed:@"big-green-button.png"] stretchableImageWithLeftCapWidth:10.0 topCapHeight:0.0] forState:UIControlStateNormal]; [btnLoadMoreItem addTarget:self action:@selector(selectLoadMoreItems:) forControlEvents:UIControlEventTouchUpInside]; [view addSubview:btnLoadMoreItem]; [btnLoadMoreItem release]; } else { UILabel* label = [[UILabel alloc] initWithFrame:CGRectMake(10,0,100,57)]; label.text = [NSString stringWithFormat:@"%d x %d", rowIndex, columnIndex]; [view addSubview:label]; [label release]; } return [view autorelease]; } - (void) selectLoadMoreItems:(id) sender { rows++; [thumbGrid setNeedsDisplay]; } - (void)viewDidLoad { [super viewDidLoad]; thumbGrid = [[DTGridView alloc] initWithFrame:CGRectMake(0,0, 320, 320)]; thumbGrid.dataSource = self; thumbGrid.gridDelegate = self; [self.view addSubview:thumbGrid]; } - (void)viewDidUnload { [super viewDidUnload]; } - (void)dealloc { [super dealloc]; } @end I implement all the methods for the DataSource, which seem to work. The grid is filled with as many rows as my int 'rows' ( +1 ) has. The last row does NOT contain 3 columns, but just one. That cell contains a button which (when pressed) adds 1 to the 'rows' integer. The problem starts, when it starts reusing cells (I am guessing) and content start disappearing. When I scroll back up, the UILabels I am putting in the cells are gone. Is there some bug, code error, mistake, dumb-ass-move I am missing here? Hope anyone can help.

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Is C# slower than VB.NET?

- by Matt Winckler

Believe it or not, despite the title, this is not a troll. Running some benchmarks this morning, my colleagues and I have discovered some strange things concerning performance, and I am wondering if we're doing something horribly wrong. We started out comparing C# vs. Delphi Prism calculating prime numbers, and found that Prism was about 30% faster. I figured maybe CodeGear did more optimization when generating IL (the exe was about twice as big as C#'s and had all sorts of different IL in it.) So I decided to write a test in VB.NET as well, assuming that Microsoft's compilers would end up writing essentially the same IL for each language. However, the result there was more shocking: C# was more than three times slower than VB running the same operations. The generated IL was different, but not extremely so, and I'm not good enough at reading it to understand the differences. As a fan of C#, this apparent slowness wounds me horribly, and I am left wondering: what in the world is going on here? Is it time to pack it all in and go write web apps in Ruby? ;-) I've included the code for each below--just copy it into a new VB or C# console app, and run. On my machine, VB finds 348513 primes in about 6.36 seconds. C# finds the same number of primes in 21.76 seconds. (I've got an Intel Core2 Quad Q6600 @2.4Ghz; on another Intel machine in the office the code for both runs much faster but the ratio is about the same; on an AMD machine here the timing is ~10 seconds for VB and ~13 for C#--much less difference, but C# is still always slower.) Both of the console applications were compiled in Release mode, but otherwise no project settings were changed from the defaults generated by Visual Studio 2008. Is it a generally-known fact that C#'s generated IL is worse than VB's? Or is this a strange edge case? Or is my code flawed somehow (most likely)? Any insights are appreciated. VB code Imports System.Diagnostics Module Module1 Private temp As List(Of Int32) Private sw As Stopwatch Private totalSeconds As Double Sub Main() serialCalc() End Sub Private Sub serialCalc() temp = New List(Of Int32)() sw = Stopwatch.StartNew() For i As Int32 = 2 To 5000000 testIfPrimeSerial(i) Next sw.Stop() totalSeconds = sw.Elapsed.TotalSeconds Console.WriteLine(String.Format("{0} seconds elapsed.", totalSeconds)) Console.WriteLine(String.Format("{0} primes found.", temp.Count)) Console.ReadKey() End Sub Private Sub testIfPrimeSerial(ByVal suspectPrime As Int32) For i As Int32 = 2 To Math.Sqrt(suspectPrime) If (suspectPrime Mod i = 0) Then Exit Sub End If Next temp.Add(suspectPrime) End Sub End Module C# Code using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Diagnostics; namespace FindPrimesCSharp { class Program { List<Int32> temp = new List<Int32>(); Stopwatch sw; double totalSeconds; static void Main(string[] args) { new Program().serialCalc(); } private void serialCalc() { temp = new List<Int32>(); sw = Stopwatch.StartNew(); for (Int32 i = 2; i <= 5000000; i++) { testIfPrimeSerial(i); } sw.Stop(); totalSeconds = sw.Elapsed.TotalSeconds; Console.WriteLine(string.Format("{0} seconds elapsed.", totalSeconds)); Console.WriteLine(string.Format("{0} primes found.", temp.Count)); Console.ReadKey(); } private void testIfPrimeSerial(Int32 suspectPrime) { for (Int32 i = 2; i <= Math.Sqrt(suspectPrime); i++) { if (suspectPrime % i == 0) return; } temp.Add(suspectPrime); } } }

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Is SHA-1 secure for password storage?

- by Tgr

Some people throw around remarks like "SHA-1 is broken" a lot, so I'm trying to understand what exactly that means. Let's assume I have a database of SHA-1 password hashes, and an attacker whith a state of the art SHA-1 breaking algorithm and a botnet with 100,000 machines gets access to it. (Having control over 100k home computers would mean they can do about 10^15 operations per second.) How much time would they need to find out the password of any one user? find out the password of a given user? find out the password of all users? find a way to log in as one of the users? find a way to log in as a specific user? How does that change if the passwords are salted? Does the method of salting (prefix, postfix, both, or something more complicated like xor-ing) matter? Here is my current understanding, after some googling. Please correct in the answers if I misunderstood something. If there is no salt, a rainbow attack will immediately find all passwords (except extremely long ones). If there is a sufficiently long random salt, the most effective way to find out the passwords is a brute force or dictionary attack. Neither collision nor preimage attacks are any help in finding out the actual password, so cryptographic attacks against SHA-1 are no help here. It doesn't even matter much what algorithm is used - one could even use MD5 or MD4 and the passwords would be just as safe (there is a slight difference because computing a SHA-1 hash is slower). To evaluate how safe "just as safe" is, let's assume that a single sha1 run takes 1000 operations and passwords contain uppercase, lowercase and digits (that is, 60 characters). That means the attacker can test 1015*60*60*24 / 1000 ~= 1017 potential password a day. For a brute force attack, that would mean testing all passwords up to 9 characters in 3 hours, up to 10 characters in a week, up to 11 characters in a year. (It takes 60 times as much for every additional character.) A dictionary attack is much, much faster (even an attacker with a single computer could pull it off in hours), but only finds weak passwords. To log in as a user, the attacker does not need to find out the exact password; it is enough to find a string that results in the same hash. This is called a first preimage attack. As far as I could find, there are no preimage attacks against SHA-1. (A bruteforce attack would take 2160 operations, which means our theoretical attacker would need 1030 years to pull it off. Limits of theoretical possibility are around 260 operations, at which the attack would take a few years.) There are preimage attacks against reduced versions of SHA-1 with negligible effect (for the reduced SHA-1 which uses 44 steps instead of 80, attack time is down from 2160 operations to 2157). There are collision attacks against SHA-1 which are well within theoretical possibility (the best I found brings the time down from 280 to 252), but those are useless against password hashes, even without salting. In short, storing passwords with SHA-1 seems perfectly safe. Did I miss something?

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Convert extended ASCII characters to it's right presentation using Console.ReadKey() method and ConsoleKeyInfo variable

- by mishamosher

Readed about 30 minutes, and didn't found some specific for this in this site. Suppose the following, in C#, console application: ConsoleKeyInfo cki; cki = Console.ReadKey(true); Console.WriteLine(cki.KeyChar.ToString()); //Or Console.WriteLine(cki.KeyChar) as well Console.ReadKey(true); Now, let's put ¿ in the console entry, and asign it to cki via a Console.ReadKey(true). What will be shown isn't the ¿ symbol, the ¨ symbol is the one that's shown instead. And the same happens with many other characters. Examples: ñ shows ¤, ¡ shows -, ´ shows ï. Now, let's take the same code snipplet and add some things for a more Console.ReadLine() like behavior: string data = string.Empty; ConsoleKeyInfo cki; for (int i = 0; i < 10; i++) { cki = Console.ReadKey(true); data += cki.KeyChar; } Console.WriteLine(data); Console.ReadKey(true); The question, how to handle this by the right way, end printing the right characters that should be stored on data, not things like ¨, ¤, -, ï, etc? Please note that I want a solution that works with ConsoleKeyInfo and Console.ReadKey(), not use other variable types, or read methods. EDIT: Because ReadKey() method, that comes from Console namespace, depends on Kernel32.dll and it definetively bad handles the extended ASCII and unicode, it's not an option anymore to just find a valid conversion for what it returns. The only valid way to handle the bad behavior of ReadKey() is to use the cki.Key property that's written in cki = Console.ReadKey(true) execution and apply a switch to it, then, return the right values on dependence of what key was pressed. For example, to handle the Ñ key pressing: string data = string.Empty; ConsoleKeyInfo cki; cki = Console.ReadKey(true); switch (cki.Key) { case ConsoleKey.Oem3: if (cki.Modifiers.ToString().Contains("Shift")) //Could added handlers for Alt and Control, but not putted in here to keep the code small and simple data += "Ñ"; else data += "ñ"; break; } Console.WriteLine(data); Console.ReadKey(true); So, now the question has a wider focus... Which others functions completes it's execution with only one key pressed, and returns what's pressed (a substitute of ReadKey())? I think that there's not such substitutes, but a confirmed answer would be usefull. EDIT2: HA! Found the way, for something I used for so many times Windows 98 SE. There are the codepages, the ones responsibles for how's presented the info in the console. ReadLine() reconfigures the codepage to use properly the extended ASCII and Unicode characters. ReadKey() leaves it in EN-US default (codepage 850). Just use a codepage that prints the characters you want, and that's all. Refer to http://en.wikipedia.org/wiki/Code_page for some of them :) So, for the Ñ key press, the solution is this: Console.OutputEncoding = Encoding.GetEncoding(1252); //Also 28591 is valid for `Ñ` key, and others too string data = string.Empty; ConsoleKeyInfo cki; cki = Console.ReadKey(true); data += cki.KeyChar; Console.WriteLine(data); Console.ReadKey(true); Simple :) Now I'm wrrr with myself... how could I forget those codepages!? Question answered, so, no more about this!

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Performance surprise with "as" and nullable types

- by Jon Skeet

I'm just revising chapter 4 of C# in Depth which deals with nullable types, and I'm adding a section about using the "as" operator, which allows you to write: object o = ...; int? x = o as int?; if (x.HasValue) { ... // Use x.Value in here } I thought this was really neat, and that it could improve performance over the C# 1 equivalent, using "is" followed by a cast - after all, this way we only need to ask for dynamic type checking once, and then a simple value check. This appears not to be the case, however. I've included a sample test app below, which basically sums all the integers within an object array - but the array contains a lot of null references and string references as well as boxed integers. The benchmark measures the code you'd have to use in C# 1, the code using the "as" operator, and just for kicks a LINQ solution. To my astonishment, the C# 1 code is 20 times faster in this case - and even the LINQ code (which I'd have expected to be slower, given the iterators involved) beats the "as" code. Is the .NET implementation of isinst for nullable types just really slow? Is it the additional unbox.any that causes the problem? Is there another explanation for this? At the moment it feels like I'm going to have to include a warning against using this in performance sensitive situations... Results: Cast: 10000000 : 121 As: 10000000 : 2211 LINQ: 10000000 : 2143 Code: using System; using System.Diagnostics; using System.Linq; class Test { const int Size = 30000000; static void Main() { object[] values = new object[Size]; for (int i = 0; i < Size - 2; i += 3) { values[i] = null; values[i+1] = ""; values[i+2] = 1; } FindSumWithCast(values); FindSumWithAs(values); FindSumWithLinq(values); } static void FindSumWithCast(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { if (o is int) { int x = (int) o; sum += x; } } sw.Stop(); Console.WriteLine("Cast: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } static void FindSumWithAs(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = 0; foreach (object o in values) { int? x = o as int?; if (x.HasValue) { sum += x.Value; } } sw.Stop(); Console.WriteLine("As: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } static void FindSumWithLinq(object[] values) { Stopwatch sw = Stopwatch.StartNew(); int sum = values.OfType<int>().Sum(); sw.Stop(); Console.WriteLine("LINQ: {0} : {1}", sum, (long) sw.ElapsedMilliseconds); } }

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How to implement an offline reader writer lock

- by Peter Morris

Some context for the question All objects in this question are persistent. All requests will be from a Silverlight client talking to an app server via a binary protocol (Hessian) and not WCF. Each user will have a session key (not an ASP.NET session) which will be a string, integer, or GUID (undecided so far). Some objects might take a long time to edit (30 or more minutes) so we have decided to use pessimistic offline locking. Pessimistic because having to reconcile conflicts would be far too annoying for users, offline because the client is not permanently connected to the server. Rather than storing session/object locking information in the object itself I have decided that any aggregate root that may have its instances locked should implement an interface ILockable public interface ILockable { Guid LockID { get; } } This LockID will be the identity of a "Lock" object which holds the information of which session is locking it. Now, if this were simple pessimistic locking I'd be able to achieve this very simply (using an incrementing version number on Lock to identify update conflicts), but what I actually need is ReaderWriter pessimistic offline locking. The reason is that some parts of the application will perform actions that read these complex structures. These include things like Reading a single structure to clone it. Reading multiple structures in order to create a binary file to "publish" the data to an external source. Read locks will be held for a very short period of time, typically less than a second, although in some circumstances they could be held for about 5 seconds at a guess. Write locks will mostly be held for a long time as they are mostly held by humans. There is a high probability of two users trying to edit the same aggregate at the same time, and a high probability of many users needing to temporarily read-lock at the same time too. I'm looking for suggestions as to how I might implement this. One additional point to make is that if I want to place a write lock and there are some read locks, I would like to "queue" the write lock so that no new read locks are placed. If the read locks are removed withing X seconds then the write lock is obtained, if not then the write lock backs off; no new read-locks would be placed while a write lock is queued. So far I have this idea The Lock object will have a version number (int) so I can detect multi-update conflicts, reload, try again. It will have a string[] for read locks A string to hold the session ID that has a write lock A string to hold the queued write lock Possibly a recursion counter to allow the same session to lock multiple times (for both read and write locks), but not sure about this yet. Rules: Can't place a read lock if there is a write lock or queued write lock. Can't place a write lock if there is a write lock or queued write lock. If there are no locks at all then a write lock may be placed. If there are read locks then a write lock will be queued instead of a full write lock placed. (If after X time the read locks are not gone the lock backs off, otherwise it is upgraded). Can't queue a write lock for a session that has a read lock. Can anyone see any problems? Suggest alternatives? Anything? I'd appreciate feedback before deciding on what approach to take.

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Find optimal strategy and AI for the game 'Proximity'?

- by smci

'Proximity' is a strategy game of territorial domination similar to Othello, Go and Risk. Two players, uses a 10x12 hex grid. Game invented by Brian Cable in 2007. Seems to be a worthy game for discussing a) optimal algorithm then b) how to build an AI. Strategies are going to be probabilistic or heuristic-based, due to the randomness factor, and the insane branching factor (20^120). So it will be kind of hard to compare objectively. A compute time limit of 5s per turn seems reasonable. Game: Flash version here and many copies elsewhere on the web Rules: here Object: to have control of the most armies after all tiles have been placed. Each turn you received a randomly numbered tile (value between 1 and 20 armies) to place on any vacant board space. If this tile is adjacent to any ally tiles, it will strengthen each tile's defenses +1 (up to a max value of 20). If it is adjacent to any enemy tiles, it will take control over them if its number is higher than the number on the enemy tile. Thoughts on strategy: Here are some initial thoughts; setting the computer AI to Expert will probably teach a lot: minimizing your perimeter seems to be a good strategy, to prevent flips and minimize worst-case damage like in Go, leaving holes inside your formation is lethal, only more so with the hex grid because you can lose armies on up to 6 squares in one move low-numbered tiles are a liability, so place them away from your main territory, near the board edges and scattered. You can also use low-numbered tiles to plug holes in your formation, or make small gains along the perimeter which the opponent will not tend to bother attacking. a triangle formation of three pieces is strong since they mutually reinforce, and also reduce the perimeter Each tile can be flipped at most 6 times, i.e. when its neighbor tiles are occupied. Control of a formation can flow back and forth. Sometimes you lose part of a formation and plug any holes to render that part of the board 'dead' and lock in your territory/ prevent further losses. Low-numbered tiles are obvious-but-low-valued liabilities, but high-numbered tiles can be bigger liabilities if they get flipped (which is harder). One lucky play with a 20-army tile can cause a swing of 200 (from +100 to -100 armies). So tile placement will have both offensive and defensive considerations. Comment 1,2,4 seem to resemble a minimax strategy where we minimize the maximum expected possible loss (modified by some probabilistic consideration of the value ß the opponent can get from 1..20 i.e. a structure which can only be flipped by a ß=20 tile is 'nearly impregnable'.) I'm not clear what the implications of comments 3,5,6 are for optimal strategy. Interested in comments from Go, Chess or Othello players. (The sequel ProximityHD for XBox Live, allows 4-player -cooperative or -competitive local multiplayer increases the branching factor since you now have 5 tiles in your hand at any given time, of which you can only play one. Reinforcement of ally tiles is increased to +2 per ally.)

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Outlook Plug-In for custom CRM

- by Optimal Solutions

I would like to write a plug-in that will allow a custom written CRM to read and write to their local Outlook client. I know that this poses a security concern. But, my clients are asking that their CRM "be connected" to Outlook. They would like to be able to do the following: A) When a contact sends them an email (reply or free standing email), they'd like the details of this email to go INTO the CRM. Yep. They would like me to save the body, time and date it was sent, etc. B) They want to be able to send new emails (or replies to existing emails) from within the CRM itself. Basically, "a form that looks like Outlook's send/reply email form". C) Want the ability to search for contacts and the related emails with a search for tags/keywords facility. (i.e. if a product name or code appears in an email then they want the email returned in the search). D) Having performed a search of many contacts, they will want to prepare a mailer and shoot out some sort of email announcement to their qualified leads. This could be 50, 100, or more persons. So its got to be able to allow bulk mailing. E) Given a list of new prospects, that arent currently contacts in the CRM, they will want to do the same and if they get replies from this mailer to the prospects, the will want the replies to be saved in the DB and contacts be inserted into the DB. F) They would like to be able to utilize the calendar and task list facilities of Outlook from the CRM, as well. More or less, they want this pretty basic (as it is today) CRM that I created to integrate with Outlook and have it do so seamlessly as if it was an add-on to the CRM. A plug-in is what I am thinking... But, I dont know where to begin. My environment is Windows XP/Vista and is going to be ASP.NET and I am going to use the VB.NET language to accomplish this. What do I need? Are there resources out there that can describe how to build a plug-in to Outlook as I have been asked to? This is not Exchange, none of the clients use exchange (not so far). They all run Outlook. Mostly 2003. Most clients are XP right now but some are upgrading to Vista. For some reason I cant seem to wrap my head around this. I think the whole security issue is thwarting my ability to see past what is probably a simple thing. The client doesnt want to be prompted by any security messages asking them if they are sure they want to send 382 emails to their contacts. Not once and certainly not 382 times. Where do I begin? I've searched the internet for similar but mainly what I found are already-written products and I've got to write this from scratch.

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strange sqares like hints in Silverlight application?

- by lina

Good day! Strange square appears on mouse hover on text boxes, buttons, etc (something like hint) in a silverlight navigation application - how can I remove it? a scrin shot an example .xaml page: <Code:BasePage x:Class="CAP.Views.Main" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="d" xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation" xmlns:Code="clr-namespace:CAP.Code" d:DesignWidth="640" d:DesignHeight="480" Title="?????? ??????? ???????? ??? ?????"> <Grid x:Name="LayoutRoot"> <Grid.RowDefinitions> <RowDefinition Height="103*" /> <RowDefinition Height="377*" /> </Grid.RowDefinitions> <Grid.ColumnDefinitions> <ColumnDefinition Width="120*" /> <ColumnDefinition Width="520*" /> </Grid.ColumnDefinitions> <Image Height="85" HorizontalAlignment="Left" Name="image1" Stretch="Fill" VerticalAlignment="Top" Width="84" Margin="12,0,0,0" ImageFailed="image1_ImageFailed" Source="/CAP;component/Images/My-Computer.png" /> <TextBlock Grid.Column="1" Height="Auto" TextWrapping="Wrap" HorizontalAlignment="Left" Margin="0,12,0,0" Name="textBlock1" Text="Good day!" VerticalAlignment="Top" FontFamily="Verdana" FontSize="16" Width="345" FontWeight="Bold" /> <TextBlock Grid.Column="1" Grid.Row="1" TextWrapping="Wrap" Height="299" HorizontalAlignment="Left" Name="textBlock2" VerticalAlignment="Top" FontFamily="Verdana" FontSize="14" Width="441" > <Run Text="Some text "/><LineBreak/><LineBreak/><Run Text="and so on"/> <LineBreak/> </TextBlock> </Grid> xaml.cs: using System; using System.Collections.Generic; using System.Linq; using System.Net; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Input; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Shapes; using System.Windows.Navigation; using CAP.Code; namespace CAP.Views { public partial class Main : BasePage { public Main() : base() { InitializeComponent(); MapBuilder.AddToMap(new SiteMapUnit() { Caption = "???????", RelativeUrl = "Main" },true); ((App)Application.Current).Mainpage.tvMainMenu.SelectedItems.Clear(); } // Executes when the user navigates to this page. protected override void OnNavigatedTo(NavigationEventArgs e) { } private void image1_ImageFailed(object sender, ExceptionRoutedEventArgs e) { } protected override string[] NeededPermission() { return new string[0]; } } } MainPage.xaml <UserControl x:Class="CAP.MainPage" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Code="clr-namespace:CAP.Code" xmlns:navigation="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Navigation" xmlns:uriMapper="clr-namespace:System.Windows.Navigation;assembly=System.Windows.Controls.Navigation" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:telerik="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls" xmlns:telerikNavigation="clr-namespace:Telerik.Windows.Controls;assembly=Telerik.Windows.Controls.Navigation" mc:Ignorable="d" Margin="0,0,0,0" Width="auto" Height="auto" xmlns:dataInput="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Data.Input"> <ScrollViewer Width="auto" Height="auto" BorderBrush="White" BorderThickness="0" Margin="0,0,0,0" x:Name="sV" HorizontalScrollBarVisibility="Auto" VerticalScrollBarVisibility="Auto" > <ScrollViewer.Content> <Grid Width="auto" Height="auto" x:Name="LayoutRoot" Style="{StaticResource LayoutRootGridStyle}" Margin="0,0,0,0"> <StackPanel Width="auto" Height="auto" Orientation="Vertical" Margin="250,0,0,50"> <Border x:Name="ContentBorder2" Margin="0,0,0,0" >  <StackPanel Orientation="Vertical" Height="82" Width="Auto" HorizontalAlignment="Right" Margin="0,0,0,0" DataContext="{Binding}"> <TextBlock HorizontalAlignment="Right" Foreground="White" x:Name="ApplicationNameTextBlock4" Style="{StaticResource ApplicationNameStyle}" FontSize="20" Text="?????? ???????" Margin="20,16,20,0"/> <StackPanel Orientation="Horizontal" HorizontalAlignment="Right"> <Image x:Name="imDoor" Visibility="Collapsed" MouseEnter="imDoor_MouseEnter" MouseLeave="imDoor_MouseLeave" Height="24" Stretch="Fill" Width="25" Margin="10,0,10,0" Source="/CAP;component/Images/sm_white_doors.png" MouseLeftButtonDown="bTest_Click" /> <TextBlock x:Name="bLogout" MouseEnter="bLogout_MouseEnter" MouseLeave="bLogout_MouseLeave" TextDecorations="Underline" Margin="0,6,20,4" Height="23" Text="?????" HorizontalAlignment="Right" Visibility="Collapsed" MouseLeftButtonDown="bTest_Click" FontFamily="Verdana" FontSize="13" FontWeight="Normal" Foreground="#FF1C1C92" /> </StackPanel> </StackPanel> </Border> <Border x:Name="bSiteMap" Margin="0,0,0,0" > <StackPanel x:Name="spSiteMap" Orientation="Horizontal" Height="20" Width="Auto" HorizontalAlignment="Left" Margin="0,0,0,0" DataContext="{Binding}">  </StackPanel> </Border> <Border Width="auto" Height="auto" x:Name="ContentBorder" Margin="0,0,0,0" > <navigation:Frame x:Name="ContentFrame" Style="{StaticResource ContentFrameStyle}" Source="Main" Navigated="ContentFrame_Navigated" NavigationFailed="ContentFrame_NavigationFailed" ToolTipService.ToolTip=" " Margin="0,0,0,0"> <navigation:Frame.UriMapper> <uriMapper:UriMapper>  <uriMapper:UriMapping Uri="RegistrateClient" MappedUri="/Views/Client/RegistrateClient.xaml"/>  </uriMapper:UriMapper> </navigation:Frame.UriMapper> </navigation:Frame> </Border> </StackPanel> <Grid x:Name="NavigationGrid" Style="{StaticResource NavigationGridStyle}" Margin="0,0,0,0" Background="{x:Null}" > <StackPanel Orientation="Vertical" Height="Auto" Width="250" HorizontalAlignment="Center" Margin="0,0,0,50" DataContext="{Binding}"> <Image Width="150" Height="90" HorizontalAlignment="Center" VerticalAlignment="Top" Source="/CAP;component/Images/logo__au.png" Margin="0,20,0,70"/> <Border x:Name="BrandingBorder" MinHeight="222" Width="250" Style="{StaticResource BrandingBorderStyle3}" HorizontalAlignment="Center" Opacity="60" Margin="0,0,0,0"> <Border.Background> <ImageBrush ImageSource="/CAP;component/Images/papka.png"/> </Border.Background> <Grid Width="250" x:Name="LichniyCabinet" Margin="0,10,0,0" HorizontalAlignment="Center" Height="211"> <Grid.ColumnDefinitions> <ColumnDefinition Width="19*" /> <ColumnDefinition Width="62*" /> <ColumnDefinition Width="151*" /> <ColumnDefinition Width="18*" /> </Grid.ColumnDefinitions> <Grid.RowDefinitions> <RowDefinition Height="13" /> <RowDefinition Height="24" /> <RowDefinition Height="35" /> <RowDefinition Height="35" /> <RowDefinition Height="43" /> <RowDefinition Height="28" /> <RowDefinition Height="32*" /> </Grid.RowDefinitions> <TextBlock Visibility="Visible" Grid.Row="2" Height="23" HorizontalAlignment="Left" x:Name="tLogin" Text="?????" VerticalAlignment="Top" FontFamily="Verdana" FontSize="13" Foreground="White" Margin="1,0,0,0" Grid.Column="1" /> <TextBlock Visibility="Visible" FontFamily="Verdana" FontSize="13" Foreground="White" Height="23" HorizontalAlignment="Left" x:Name="tPassw" Text="??????" VerticalAlignment="Top" Grid.Row="3" Grid.Column="1" /> <TextBox Visibility="Visible" Grid.Column="2" Grid.Row="2" Height="24" HorizontalAlignment="Left" x:Name="logLogin" VerticalAlignment="Top" Width="150" /> <PasswordBox Visibility="Visible" Code:DefaultButtonService.DefaultButton="{Binding ElementName=bLogin}" PasswordChar="*" Height="24" HorizontalAlignment="Left" x:Name="logPassword" VerticalAlignment="Top" Width="150" Grid.Column="2" Grid.Row="3" /> <Button x:Name="bLogin" MouseEnter="bLogin_MouseEnter" MouseLeave="bLogin_MouseLeave" Visibility="Visible" Content="?????" Grid.Column="2" Grid.Row="4" Click="Button_Click" Height="23" HorizontalAlignment="Left" Margin="81,0,0,0" VerticalAlignment="Top" Width="70" /> <TextBlock MouseLeftButtonDown="ForgotPassword_MouseLeftButtonDown" MouseEnter="ForgotPassword_MouseEnter" MouseLeave="ForgotPassword_MouseLeave" Visibility="Visible" TextDecorations="Underline" Grid.ColumnSpan="2" Grid.Row="4" Height="23" HorizontalAlignment="Left" x:Name="ForgotPassword" Text="?????? ???????" VerticalAlignment="Top" Foreground="White" FontFamily="Verdana" FontSize="13" Grid.Column="1" /> <TextBlock MouseEnter="tbRegistration_MouseEnter" MouseLeave="tbRegistration_MouseLeave" MouseLeftButtonDown="tbRegistration_MouseLeftButtonDown" Grid.Column="2" Grid.Row="6" Height="23" x:Name="tbRegistration" TextDecorations="Underline" Text="???????????" VerticalAlignment="Top" FontFamily="Verdana" FontSize="13" TextAlignment="Center" HorizontalAlignment="Center" Foreground="#FF1C1C92" FontWeight="Normal" Margin="0,0,57,0" /> <TextBlock Cursor="Arrow" Height="23" HorizontalAlignment="Left" Margin="11,-3,0,0" Text="?????? ???????" VerticalAlignment="Top" Grid.ColumnSpan="3" Grid.RowSpan="2" FontFamily="Verdana" FontSize="13" FontWeight="Bold" Foreground="White" /> <Image Visibility="Collapsed" Height="70" x:Name="imUser" Stretch="Fill" Width="70" Grid.ColumnSpan="2" Margin="11,0,0,0" Grid.Row="2" Grid.RowSpan="2" Source="/CAP;component/Images/user2.png" /> <TextBlock x:Name="tbHello" Grid.Column="2" Visibility="Collapsed" Grid.Row="2" Height="auto" TextWrapping="Wrap" HorizontalAlignment="Left" Margin="6,0,0,0" Text="" VerticalAlignment="Top" FontFamily="Verdana" FontSize="13" Foreground="White" Width="145" /> </Grid> </Border> <Border x:Name="MenuBorder" Margin="0,0,0,50" Width="250" Visibility="Collapsed"> <StackPanel x:Name="spMenu" Width="240" HorizontalAlignment="Left"> <telerikNavigation:RadTreeView x:Name="tvMainMenu" Width="240" Selected="TreeView1_Selected" SelectedValuePath="Text" telerik:Theming.Theme="Windows7" FontFamily="Verdana" FontSize="12"/> </StackPanel> </Border> </StackPanel> </Grid> <Border x:Name="FooterBorder" VerticalAlignment="Bottom" Width="auto" Height="76"> <Border.Background> <ImageBrush ImageSource="/CAP;component/Images/footer2.png" /> </Border.Background> <TextBlock x:Name="tbFooter" Height="24" Width="auto" Margin="0,20,0,0" TextAlignment="Center" HorizontalAlignment="Stretch" VerticalAlignment="Center" Foreground="White" FontFamily="Verdana" FontSize="11"> </TextBlock> </Border> </Grid> </ScrollViewer.Content> </ScrollViewer> </UserControl> MainPage.xaml.cs using System; using System.Collections.Generic; using System.Linq; using System.Windows; using System.Windows.Controls; using System.Windows.Documents; using System.Windows.Navigation; using CAP.Code; using CAP.Registrator; using System.Windows.Input; using System.ComponentModel.DataAnnotations; using System.Windows.Browser; using Telerik.Windows.Controls; using System.Net; using System.Windows.Media; using System.Windows.Media.Animation; using System.Windows.Navigation; using System.Windows.Shapes; namespace CAP { public partial class MainPage { public App Appvars = Application.Current as App; private readonly RegistratorClient registrator; public SiteMapBuilder builder; public MainPage() { InitializeComponent(); sV.SetIsMouseWheelScrollingEnabled(true); builder = new SiteMapBuilder(spSiteMap); try { //working with service } catch { this.ContentFrame.Navigate(new Uri(String.Format("ErrorPage"), UriKind.RelativeOrAbsolute)); } } /// Recursive method to update the correct scrollviewer (if exists) private ScrollViewer CheckParent(FrameworkElement element) { ScrollViewer _result = element as ScrollViewer; if (element != null && _result == null) { FrameworkElement _temp = element.Parent as FrameworkElement; _result = CheckParent(_temp); } return _result; } // If an error occurs during navigation, show an error window private void ContentFrame_NavigationFailed(object sender, NavigationFailedEventArgs e) { e.Handled = true; ChildWindow errorWin = new ErrorWindow(e.Uri); errorWin.Show(); } } }

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EXSLT date:format-date template without document() XSLT 1.0

- by DashaLuna

Hello guys, I'm using date:format-date template EXSLT file I'm using XSLT 1.0 and MSXML3.0 as the processor. My date:format-date template EXSLT file's declaration is: <xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:msxsl="urn:schemas-microsoft-com:xslt" xmlns:tui="http://www.travelbound.co.uk/" xmlns:date="http://exslt.org/dates-and-times" exclude-result-prefixes="msxsl tui date" version="1.0"> ... </xsl:stylesheet> I cannot use document() function due to the 3rd party restrictions. So I have changed the months and days (similarly) from XML snippet: <date:months> <date:month length="31" abbr="Jan">January</date:month> <date:month length="28" abbr="Feb">February</date:month> <date:month length="31" abbr="Mar">March</date:month> <date:month length="30" abbr="Apr">April</date:month> <date:month length="31" abbr="May">May</date:month> <date:month length="30" abbr="Jun">June</date:month> <date:month length="31" abbr="Jul">July</date:month> <date:month length="31" abbr="Aug">August</date:month> <date:month length="30" abbr="Sep">September</date:month> <date:month length="31" abbr="Oct">October</date:month> <date:month length="30" abbr="Nov">November</date:month> <date:month length="31" abbr="Dec">December</date:month> </date:months> to the variable: <xsl:variable name="months"> <month length="31" abbr="Jan">January</month> <month length="28" abbr="Feb">February</month> <month length="31" abbr="Mar">March</month> <month length="30" abbr="Apr">April</month> <month length="31" abbr="May">May</month> <month length="30" abbr="Jun">June</month> <month length="31" abbr="Jul">July</month> <month length="31" abbr="Aug">August</month> <month length="30" abbr="Sep">September</month> <month length="31" abbr="Oct">October</month> <month length="30" abbr="Nov">November</month> <month length="31" abbr="Dec">December</month> </xsl:variable> And correspondingly, I've changed the code that originally uses document() function from: [from month processing bit of EXSLT stylesheet] <xsl:variable name="month-node" select="document('')/*/date:months/date:month[number($month)]" /> to use MSXML3.0 node-set function: <xsl:variable name="month-node" select="msxsl:node-set($months)/month[number($month)]" /> So I assumed that this would work. According to the EXLT instructions "The format pattern string is interpreted as described for the JDK 1.1 SimpleDateFormat class." [I used current version]. I'm specifing the month in accordance to SimpleDateFormat class as 'dd MMMMM yyyy' so that the month will be the full month's name, for example January. But it doesn't work :( I've looked in EXSLT stylesheet and it has got the logic to do that. Also there is logic to display the name of the week for a day using 'E' pattern, which doesn't work for me. Maybe changing from using document() to variables broke it. Would really appreciate any help. Many thanks!

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invalid context 0x0 under iOS 7.0 and system degradation

- by Alex

I've read as many search results I could find on this dreaded problem, unfortunatelly, each one seems to focus on a specific function call. My problem is that I get the same error from multiple functions, which I am guessing are being called back from functions that I use. To make matters worse, the actual code is within a custom private framework which is being imported in another project, and as such, debugging isn't as simple? Can anyone point me to the right direction? I have a feeling I'm calling certain methods wrongly or with bad context, but the output from xcode is not very helpful at this point. : CGContextSetFillColorWithColor: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextSetStrokeColorWithColor: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. CGContextSaveGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextSetFlatness: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextAddPath: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextDrawPath: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextRestoreGState: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. : CGContextGetBlendMode: invalid context 0x0. This is a serious error. This application, or a library it uses, is using an invalid context and is thereby contributing to an overall degradation of system stability and reliability. This notice is a courtesy: please fix this problem. It will become a fatal error in an upcoming update. Those errors may occur when a custom view is presented, or one of its inherited classes. At which point they spawn multiple times, until the keyboard won't provide any input. Touch events are still registered, but system slows down, and eventually may lead to unallocated object errors.

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Const references when dereferencing iterator on set, starting from Visual Studio 2010

- by Patrick

Starting from Visual Studio 2010, iterating over a set seems to return an iterator that dereferences the data as 'const data' instead of non-const. The following code is an example of something that does compile on Visual Studio 2005, but not on 2010 (this is an artificial example, but clearly illustrates the problem we found on our own code). In this example, I have a class that stores a position together with a temperature. I define comparison operators (not all them, just enough to illustrate the problem) that only use the position, not the temperature. The point is that for me two instances are identical if the position is identical; I don't care about the temperature. #include <set> class DataPoint { public: DataPoint (int x, int y) : m_x(x), m_y(y), m_temperature(0) {} void setTemperature(double t) {m_temperature = t;} bool operator<(const DataPoint& rhs) const { if (m_x==rhs.m_x) return m_y<rhs.m_y; else return m_x<rhs.m_x; } bool operator==(const DataPoint& rhs) const { if (m_x!=rhs.m_x) return false; if (m_y!=rhs.m_y) return false; return true; } private: int m_x; int m_y; double m_temperature; }; typedef std::set<DataPoint> DataPointCollection; void main(void) { DataPointCollection points; points.insert (DataPoint(1,1)); points.insert (DataPoint(1,1)); points.insert (DataPoint(1,2)); points.insert (DataPoint(1,3)); points.insert (DataPoint(1,1)); for (DataPointCollection::iterator it=points.begin();it!=points.end();++it) { DataPoint &point = *it; point.setTemperature(10); } } In the main routine I have a set to which I add some points. To check the correctness of the comparison operator, I add data points with the same position multiple times. When writing the contents of the set, I can clearly see there are only 3 points in the set. The for-loop loops over the set, and sets the temperature. Logically this is allowed, since the temperature is not used in the comparison operators. This code compiles correctly in Visual Studio 2005, but gives compilation errors in Visual Studio 2010 on the following line (in the for-loop): DataPoint &point = *it; The error given is that it can't assign a "const DataPoint" to a [non-const] "DataPoint &". It seems that you have no decent (= non-dirty) way of writing this code in VS2010 if you have a comparison operator that only compares parts of the data members. Possible solutions are: Adding a const-cast to the line where it gives an error Making temperature mutable and making setTemperature a const method But to me both solutions seem rather 'dirty'. It looks like the C++ standards committee overlooked this situation. Or not? What are clean solutions to solve this problem? Did some of you encounter this same problem and how did you solve it? Patrick

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Using UUIDs for cheap equals() and hashCode()

- by Tom McIntyre

I have an immutable class, TokenList, which consists of a list of Token objects, which are also immutable: @Immutable public final class TokenList { private final List<Token> tokens; public TokenList(List<Token> tokens) { this.tokens = Collections.unmodifiableList(new ArrayList(tokens)); } public List<Token> getTokens() { return tokens; } } I do several operations on these TokenLists that take multiple TokenLists as inputs and return a single TokenList as the output. There can be arbitrarily many TokenLists going in, and each can have arbitrarily many Tokens. These operations are expensive, and there is a good chance that the same operation (ie the same inputs) will be performed multiple times, so I would like to cache the outputs. However, performance is critical, and I am worried about the expense of performing hashCode() and equals() on these objects that may contain arbitrarily many elements (as they are immutable then hashCode could be cached, but equals will still be expensive). This led me to wondering whether I could use a UUID to provide equals() and hashCode() simply and cheaply by making the following updates to TokenList: @Immutable public final class TokenList { private final List<Token> tokens; private final UUID uuid; public TokenList(List<Token> tokens) { this.tokens = Collections.unmodifiableList(new ArrayList(tokens)); this.uuid = UUID.randomUUID(); } public List<Token> getTokens() { return tokens; } public UUID getUuid() { return uuid; } } And something like this to act as a cache key: @Immutable public final class TopicListCacheKey { private final UUID[] uuids; public TopicListCacheKey(TopicList... topicLists) { uuids = new UUID[topicLists.length]; for (int i = 0; i < uuids.length; i++) { uuids[i] = topicLists[i].getUuid(); } } @Override public int hashCode() { return Arrays.hashCode(uuids); } @Override public boolean equals(Object other) { if (other == this) return true; if (other instanceof TopicListCacheKey) return Arrays.equals(uuids, ((TopicListCacheKey) other).uuids); return false; } } I figure that there are 2^128 different UUIDs and I will probably have at most around 1,000,000 TokenList objects active in the application at any time. Given this, and the fact that the UUIDs are used combinatorially in cache keys, it seems that the chances of this producing the wrong result are vanishingly small. Nevertheless, I feel uneasy about going ahead with it as it just feels 'dirty'. Are there any reasons I should not use this system? Will the performance costs of the SecureRandom used by UUID.randomUUID() outweigh the gains (especially since I expect multiple threads to be doing this at the same time)? Are collisions going to be more likely than I think? Basically, is there anything wrong with doing it this way?? Thanks.

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How should I clean up hung grandchild processes when an alarm trips in Perl?

- by brian d foy

I have a parallelized automation script which needs to call many other scripts, some of which hang because they (incorrectly) wait for standard input. That's not a big deal because I catch those with alarm. The trick is to shut down those hung grandchild processes when the child shuts down. I thought various incantations of SIGCHLD, waiting, and process groups could do the trick, but they all block and the grandchildren aren't reaped. My solution, which works, just doesn't seem like it is the right solution. I'm not especially interested in the Windows solution just yet, but I'll eventually need that too. Mine only works for Unix, which is fine for now. I wrote a small script that takes the number of simultaneous parallel children to run and the total number of forks: $ fork_bomb <parallel jobs> <number of forks> $ fork_bomb 8 500 This will probably hit the per-user process limit within a couple of minutes. Many solutions I've found just tell you to increase the per-user process limit, but I need this to run about 300,000 times, so that isn't going to work. Similarly, suggestions to re-exec and so on to clear the process table aren't what I need. I'd like to actually fix the problem instead of slapping duct tape over it. I crawl the process table looking for the child processes and shut down the hung processes individually in the SIGALRM handler, which needs to die because the rest of real code has no hope of success after that. The kludgey crawl through the process table doesn't bother me from a performance perspective, but I wouldn't mind not doing it: use Parallel::ForkManager; use Proc::ProcessTable; my $pm = Parallel::ForkManager->new( $ARGV[0] ); my $alarm_sub = sub { kill 9, map { $_->{pid} } grep { $_->{ppid} == $$ } @{ Proc::ProcessTable->new->table }; die "Alarm rang for $$!\n"; }; foreach ( 0 .. $ARGV[1] ) { print "."; print "\n" unless $count++ % 50; my $pid = $pm->start and next; local $SIG{ALRM} = $alarm_sub; eval { alarm( 2 ); system "$^X -le '<STDIN>'"; # this will hang alarm( 0 ); }; $pm->finish; } If you want to run out of processes, take out the kill. I thought that setting a process group would work so I could kill everything together, but that blocks: my $alarm_sub = sub { kill 9, -$$; # blocks here die "Alarm rang for $$!\n"; }; foreach ( 0 .. $ARGV[1] ) { print "."; print "\n" unless $count++ % 50; my $pid = $pm->start and next; setpgrp(0, 0); local $SIG{ALRM} = $alarm_sub; eval { alarm( 2 ); system "$^X -le '<STDIN>'"; # this will hang alarm( 0 ); }; $pm->finish; } The same thing with POSIX's setsid didn't work either, and I think that actually broke things in a different way since I'm not really daemonizing this. Curiously, Parallel::ForkManager's run_on_finish happens too late for the same clean-up code: the grandchildren are apparently already disassociated from the child processes at that point.

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Postmortem debugging with WinDBG.

- by Drazar

I have an WCF-service running on an server, and occasionally(1-2 times every month) it throws an COMException with the informative message ”Unknown error (0x8005008)”. When i googled for this particular error I only got threads about problems when creating virtual directories in IIS. And the source code hasn’t anything with making a virtual directory in IIS. DirectoryServiceLib.LdapProvider.Directory - CreatePost - Could not create employee for 195001010000,000000000000: System.Runtime.InteropServices.COMException (0x80005008): Unknown error (0x80005008) at System.DirectoryServices.PropertyValueCollection.PopulateList I've taken a memorydump when I catch the Exception for further analysis in WinDBG. After switching to the right thread I executed the !CLRStack command: 000000001b8ab6d8 000000007708671a [NDirectMethodFrameStandalone: 000000001b8ab6d8] Common.MemoryDump.MiniDumpWriteDump(IntPtr, Int32, IntPtr, MINIDUMP_TYPE, IntPtr, IntPtr, IntPtr) 000000001b8ab680 000007ff002808d8 DomainBoundILStubClass.IL_STUB_PInvoke(IntPtr, Int32, IntPtr, MINIDUMP_TYPE, IntPtr, IntPtr, IntPtr) 000000001b8ab780 000007ff00280812 Common.MemoryDump.CreateMiniDump(System.String) 000000001b8ab7e0 000007ff0027b218 DirectoryServiceLib.LdapProvider.Directory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String) 000000001b8ad6d8 000007fef8816869 [HelperMethodFrame: 000000001b8ad6d8] 000000001b8ad820 000007feec2b6c6f System.DirectoryServices.PropertyValueCollection.PopulateList() 000000001b8ad860 000007feec225f0f System.DirectoryServices.PropertyValueCollection..ctor(System.DirectoryServices.DirectoryEntry, System.String) 000000001b8ad8a0 000007feec22d023 System.DirectoryServices.PropertyCollection.get_Item(System.String) 000000001b8ad8f0 000007ff00274d34 Common.DirectoryEntryExtension.GetStringAttribute(System.String) 000000001b8ad940 000007ff0027f507 DirectoryServiceLib.LdapProvider.DirectoryPost.Copy(DirectoryServiceLib.LdapProvider.DirectoryPost) 000000001b8ad980 000007ff0027a7cf DirectoryServiceLib.LdapProvider.Directory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String) 000000001b8adbe0 000007ff00279532 DirectoryServiceLib.WCFDirectory.CreatePost(System.String, DirectoryServiceLib.Model.Post, DirectoryServiceLib.Model.Presumptions, Services.Common.SourceEnum, System.String) 000000001b8adc60 000007ff001f47bd DynamicClass.SyncInvokeCreatePost(System.Object, System.Object[], System.Object[]) My conclusion is that it fails when the code is calling System.DirectoryServices.PropertyCollection.get_Item(System.String). So after issuing an !CLRStack -a I get this result: 000000001b8ad8a0 000007feec22d023 System.DirectoryServices.PropertyCollection.get_Item(System.String) PARAMETERS: this = <no data> propertyName = <no data> LOCALS: <CLR reg> = 0x0000000001dcef78 <no data> My very first question is why does it display no data on the propertyname? I am kinda new on Windbg. However I executed an dumpobject on = 0x0000000001dcef78: 0:013> !do 0x0000000001dcef78 Name: System.String MethodTable: 000007fef66d6960 EEClass: 000007fef625eec8 Size: 74(0x4a) bytes File: C:\Windows\Microsoft.Net\assembly\GAC_64\mscorlib\v4.0_4.0.0.0__b77a5c561934e089\mscorlib.dll String: personalprescriptioncode Fields: MT Field Offset Type VT Attr Value Name 000007fef66dc848 40000ed 8 System.Int32 1 instance 24 m_stringLength 000007fef66db388 40000ee c System.Char 1 instance 70 m_firstChar 000007fef66d6960 40000ef 10 System.String 0 shared static Empty >> Domain:Value 0000000000174e10:00000000019d1420 000000001a886f50:00000000019d1420 << So when the source code wants to fetch the personalprescriptioncode from Active Directory(what is used for persistence layer) it fails. Looking back at the stack it is when issuing the Copy method. DirectoryServiceLib.LdapProvider.DirectoryPost.Copy(DirectoryServiceLib.LdapProvider.DirectoryPost) So looking in the sourcecode: DirectoryPost postInLimbo = DirectoryPostFactory.Instance().GetDirectoryPost(LdapConfigReader.Instance().GetConfigValue("LimboDN"), idGenPerson.ID.UserId); if (postInLimbo != null) newPost.Copy(postInLimbo); This code is looking for another post in OU=limbo with the same UserId and if it finds one it copies the attributes to the new post. In this case it does and it fails with personalprescriptioncode. I've looked in Active Directory under OU=Limbo and the post exist there with the attribute personalprescriptioncode=31243. Question 1: Why does it display no data for some of the PARAMETERS and LOCALS? Is it the GC who has cleaned up before the memorydump had been created. Question 2: Is there anymore i can do to get to the solution to this problem?

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Why does BeginReceiveFrom never time out?

- by James Hugard

I am writing an asynchronous Ping using Raw Sockets in F#, to enable parallel requests using as few threads as possible ("System.Net.NetworkInformation.Ping" appears to use one thread per request, but have not tested this... also am interested in using F# async workflows). The synchronous version below correctly times out when the target host does not exist/respond, but the asynchronous version hangs. Both work when the host does respond... Any ideas? (note: the process must run as Admin for this code to work) This throws a timeout: let result = Ping.Ping ( IPAddress.Parse( "192.168.33.22" ), 1000 ) However, this hangs: let result = Ping.PingAsync ( IPAddress.Parse( "192.168.33.22" ), 1000 ) |> Async.RunSynchronously Here's the code... module Ping open System open System.Net open System.Net.Sockets open System.Threading //---- ICMP Packet Classes type IcmpMessage (t : byte) = let mutable m_type = t let mutable m_code = 0uy let mutable m_checksum = 0us member this.Type with get() = m_type member this.Code with get() = m_code member this.Checksum = m_checksum abstract Bytes : byte array default this.Bytes with get() = [| m_type m_code byte(m_checksum) byte(m_checksum >>> 8) |] member this.GetChecksum() = let mutable sum = 0ul let bytes = this.Bytes let mutable i = 0 // Sum up uint16s while i < bytes.Length - 1 do sum <- sum + uint32(BitConverter.ToUInt16( bytes, i )) i <- i + 2 // Add in last byte, if an odd size buffer if i <> bytes.Length then sum <- sum + uint32(bytes.[i]) // Shuffle the bits sum <- (sum >>> 16) + (sum &&& 0xFFFFul) sum <- sum + (sum >>> 16) sum <- ~~~sum uint16(sum) member this.UpdateChecksum() = m_checksum <- this.GetChecksum() type InformationMessage (t : byte) = inherit IcmpMessage(t) let mutable m_identifier = 0us let mutable m_sequenceNumber = 0us member this.Identifier = m_identifier member this.SequenceNumber = m_sequenceNumber override this.Bytes with get() = Array.append (base.Bytes) [| byte(m_identifier) byte(m_identifier >>> 8) byte(m_sequenceNumber) byte(m_sequenceNumber >>> 8) |] type EchoMessage() = inherit InformationMessage( 8uy ) let mutable m_data = Array.create 32 32uy do base.UpdateChecksum() member this.Data with get() = m_data and set(d) = m_data <- d this.UpdateChecksum() override this.Bytes with get() = Array.append (base.Bytes) (this.Data) //---- Synchronous Ping let Ping (host : IPAddress, timeout : int ) = let mutable ep = new IPEndPoint( host, 0 ) let socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let mutable buffer = packet.Bytes try if socket.SendTo( buffer, ep ) <= 0 then raise (SocketException()) buffer <- Array.create (buffer.Length + 20) 0uy let mutable epr = ep :> EndPoint if socket.ReceiveFrom( buffer, &epr ) <= 0 then raise (SocketException()) finally socket.Close() buffer //---- Entensions to the F# Async class to allow up to 5 paramters (not just 3) type Async with static member FromBeginEnd(arg1,arg2,arg3,arg4,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,iar,state)), endAction, ?cancelAction=cancelAction) static member FromBeginEnd(arg1,arg2,arg3,arg4,arg5,beginAction,endAction,?cancelAction): Async<'T> = Async.FromBeginEnd((fun (iar,state) -> beginAction(arg1,arg2,arg3,arg4,arg5,iar,state)), endAction, ?cancelAction=cancelAction) //---- Extensions to the Socket class to provide async SendTo and ReceiveFrom type System.Net.Sockets.Socket with member this.AsyncSendTo( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginSendTo, this.EndSendTo ) member this.AsyncReceiveFrom( buffer, offset, size, socketFlags, remoteEP ) = Async.FromBeginEnd( buffer, offset, size, socketFlags, remoteEP, this.BeginReceiveFrom, (fun asyncResult -> this.EndReceiveFrom(asyncResult, remoteEP) ) ) //---- Asynchronous Ping let PingAsync (host : IPAddress, timeout : int ) = async { let ep = IPEndPoint( host, 0 ) use socket = new Socket( AddressFamily.InterNetwork, SocketType.Raw, ProtocolType.Icmp ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.SendTimeout, timeout ) socket.SetSocketOption( SocketOptionLevel.Socket, SocketOptionName.ReceiveTimeout, timeout ) let packet = EchoMessage() let outbuffer = packet.Bytes try let! result = socket.AsyncSendTo( outbuffer, 0, outbuffer.Length, SocketFlags.None, ep ) if result <= 0 then raise (SocketException()) let epr = ref (ep :> EndPoint) let inbuffer = Array.create (outbuffer.Length + 256) 0uy let! result = socket.AsyncReceiveFrom( inbuffer, 0, inbuffer.Length, SocketFlags.None, epr ) if result <= 0 then raise (SocketException()) return inbuffer finally socket.Close() }

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SDL side-scroller scrolls inconsistantly

- by SDLFunTimes

So I'm working on an upgrade from my previous project (that I posted here for code review) this time implementing a repeating background (like what is used on cartoons) so that SDL doesn't have to load really big images for a level. There's a strange inconsistency in the program, however: the first time the user scrolls all the way to the right 2 less panels are shown than is specified. Going backwards (left) the correct number of panels is shown (that is the panels repeat the number of times specified in the code). After that it appears that going right again (once all the way at the left) the correct number of panels is shown and same going backwards. Here's some selected code and here's a .zip of all my code constructor: Game::Game(SDL_Event* event, SDL_Surface* scr, int level_w, int w, int h, int bpp) { this->event = event; this->bpp = bpp; level_width = level_w; screen = scr; w_width = w; w_height = h; //load images and set rects background = format_surface("background.jpg"); person = format_surface("person.png"); background_rect_left = background->clip_rect; background_rect_right = background->clip_rect; current_background_piece = 1; //we are displaying the first clip rect_in_view = &background_rect_right; other_rect = &background_rect_left; person_rect = person->clip_rect; background_rect_left.x = 0; background_rect_left.y = 0; background_rect_right.x = background->w; background_rect_right.y = 0; person_rect.y = background_rect_left.h - person_rect.h; person_rect.x = 0; } and here's the move method which is probably causing all the trouble: void Game::move(SDLKey direction) { if(direction == SDLK_RIGHT) { if(move_screen(direction)) { if(!background_reached_right()) { //move background right background_rect_left.x += movement_increment; background_rect_right.x += movement_increment; if(rect_in_view->x >= 0) { //move the other rect in to fill the empty space SDL_Rect* temp; other_rect->x = -w_width + rect_in_view->x; temp = rect_in_view; rect_in_view = other_rect; other_rect = temp; current_background_piece++; std::cout << current_background_piece << std::endl; } if(background_overshoots_right()) { //sees if this next blit is past the surface //this is used only for re-aligning the rects when //the end of the screen is reached background_rect_left.x = 0; background_rect_right.x = w_width; } } } else { //move the person instead person_rect.x += movement_increment; if(get_person_right_side() > w_width) { //person went too far right person_rect.x = w_width - person_rect.w; } } } else if(direction == SDLK_LEFT) { if(move_screen(direction)) { if(!background_reached_left()) { //moves background left background_rect_left.x -= movement_increment; background_rect_right.x -= movement_increment; if(rect_in_view->x <= -w_width) { //swap the rect in view SDL_Rect* temp; rect_in_view->x = w_width; temp = rect_in_view; rect_in_view = other_rect; other_rect = temp; current_background_piece--; std::cout << current_background_piece << std::endl; } if(background_overshoots_left()) { background_rect_left.x = 0; background_rect_right.x = w_width; } } } else { //move the person instead person_rect.x -= movement_increment; if(person_rect.x < 0) { //person went too far left person_rect.x = 0; } } } } without the rest of the code this doesn't make too much sense. Since there is too much of it I'll upload it here for testing. Anyway does anyone know how I could fix this inconsistency?

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How do I explain this to potential employers?

- by ReferencelessBob

Backstory: TL;DR: I've gained a lot of experience working for 5 years at one startup company, but it eventually failed. The company is gone and the owner MIA. When I left sixth-form college I didn't want to start a degree straight away, so when I met this guy who knew a guy who was setting up a publishing company and needed a 'Techie' I thought why not. It was a very small operation, he sent mailings to schools, waited for orders to start arriving, then ordered a short run of the textbooks to be printed, stuck them in an envelope posted them out. I was initially going to help him set up a computerized system for recording orders and payments, printing labels, really basic stuff and I threw it together in Access in a couple of weeks. He also wanted to start taking orders online, so I set up a website and a paypal business account. While I was doing this, I was also helping to do the day-to-day running of things, taking phone orders, posting products, banking cheques, ordering textbooks, designing mailings, filing end of year accounts, hiring extra staff, putting stamps on envelopes. I learned so much about things I didn't even know I needed to learn about. Things were pretty good, when I started we sold about £10,000 worth of textbooks and by my 4th year there we sold £250,000 worth of text books. Things were looking good, but we had a problem. Our best selling product had peaked and sales started to fall sharply, we introduced add on products through the website to boost sales which helped for a while, but we had simply saturated the market. Our plan was to enter the US with our star product and follow the same, slightly modified, plan as before. We setup a 1-866 number and had the calls forwarded to our UK offices. We contracted a fulfillment company, shipped over a few thousand textbooks, had a mailing printed and mailed, then sat by the phones and waited. Needless to say, it didn't work. We tried a few other things, at home and in the US, but nothing helped. We expanded in the good times, moving into bigger offices, taking on staff to do administrative and dispatch work, but now cashflow was becoming a problem and things got tougher. We did the only thing we could and scaled things right back, the offices went, the admin staff went, I stopped taking a wage and started working from home. Nothing helped. The business was wound up about about 2 years ago. In the end it turned out that the owner had built up considerable debt at the start of business and had not paid them off during good years, which left him in a difficult position when cashflow had started to dry up. I haven't been able to contact the owner since I found out. It took me a while to get back on my feet after that, but I'm now at University and doing a Computer Science degree. How do I show the experience I have without having to get into all the gory details of what happened?

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C program runs in Cygwin but not Linux (Malloc)

- by Shawn

I have a heap allocation error that I cant spot in my code that is picked up on vanguard/gdb on Linux but runs perfectly on a Windows cygwin environment. I understand that Linux could be tighter with its heap allocation than Windows but I would really like to have a response that discovers the issue/possible fix. I'm also aware that I shouldn't typecast malloc in C but it's a force of habit and doesn't change my problem from happening. My program actually compiles without error on both Linux & Windows but when I run it in Linux I get a scary looking result: malloc.c:3074: sYSMALLOc: Assertion `(old_top == (((mbinptr) (((char *) &((av)-bins[((1) - 1) * 2])) - __builtin_offsetof (struct malloc_chunk, fd)))) && old_size == 0) || ((unsigned long) (old_size) = (unsigned long)((((__builtin_offsetof (struct malloc_chunk, fd_nextsize))+((2 * (sizeof(size_t))) - 1)) & ~((2 * (sizeof(size_t))) - 1))) && ((old_top)-size & 0x1) && ((unsigned long)old_end & pagemask) == 0)' failed. Aborted Attached snippet from my code that is being pointed to as the error for review: /* Main */ int main(int argc, char * argv[]) { FILE *pFile; unsigned char *buffer; long int lSize; pFile = fopen ( argv[1] , "r" ); if (pFile==NULL) {fputs ("File error on arg[1]",stderr); return 1;} fseek (pFile , 0 , SEEK_END); lSize = ftell (pFile); rewind (pFile); buffer = (char*) malloc(sizeof(char) * lSize+1); if (buffer == NULL) {fputs ("Memory error",stderr); return 2;} bitpair * ppairs = (bitpair *) malloc(sizeof(bitpair) * (lSize+1)); //line 51 below calcpair(ppairs, (lSize+1)); /* irrelevant stuff */ fclose(pFile); free(buffer); free(ppairs); } typedef struct { long unsigned int a; //not actual variable names... Yes I need them to be long unsigned long unsigned int b; long unsigned int c; long unsigned int d; long unsigned int e; } bitpair; void calcpair(bitpair * ppairs, long int bits); void calcPairs(bitpair * ppairs, long int bits) { long int i, top, bot, var_1, var_2; int count = 0; for(i = 0; i < cs; i++) { top = 0; ppairs[top].e = 1; do { bot = count; count++; } while(ppairs[bot].e != 0); ppairs[bot].e = 1; var_1 = bot; var_2 = top; calcpair * bp = &ppairs[var_2]; bp->a = var_2; bp->b = var_1; bp->c = i; bp = &ppairs[var_1]; bp->a = var_2; bp->b = var_1; bp->c = i; } return; } gdb reports: free(): invalid pointer: 0x0000000000603290 * valgrind reports the following message 5 times before exiting due to "VALGRIND INTERNAL ERROR" signal 11 (SIGSEGV): Invalid read of size 8 ==2727== at 0x401043: calcPairs (in /home/user/Documents/5-3/ubuntu test/main) ==2727== by 0x400C9A: main (main.c:51) ==2727== Address 0x5a607a0 is not stack'd, malloc'd or (recently) free'd

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Why does C# thread die?

- by JackN

This is my 1st C# project so I may be doing something obviously improper in the code below. I am using .NET, WinForms (I think), and this is a desktop application until I get the bugs out. UpdateGui() uses Invoke((MethodInvoker)delegate to update various GUI controls based on received serial data and sends a GetStatus() command out the serial port 4 times a second. Thread Read() reads the response from serial port whenever it arrives which should be near immediate. SerialPortFixer is a SerialPort IOException Workaround in C# I found at http://zachsaw.blogspot.com/2010/07/serialport-ioexception-workaround-in-c.html. After one or both threads die I'll see something like The thread 0x1288 has exited with code 0 (0x0). in the debug code output. Why do UpdateGui() and/or Read() eventually die? public partial class UpdateStatus : Form { private readonly byte[] Command = new byte[32]; private readonly byte[] Status = new byte[32]; readonly Thread readThread; private static readonly Mutex commandMutex = new Mutex(); private static readonly Mutex statusMutex = new Mutex(); ... public UpdateStatus() { InitializeComponent(); SerialPortFixer.Execute("COM2"); if (serialPort1.IsOpen) { serialPort1.Close(); } try { serialPort1.Open(); } catch (Exception e) { labelWarning.Text = LOST_COMMUNICATIONS + e; labelStatus.Text = LOST_COMMUNICATIONS + e; labelWarning.Visible = true; } readThread = new Thread(Read); readThread.Start(); new Timer(UpdateGui, null, 0, 250); } static void ProcessStatus(byte[] status) { Status.State = (State) status[4]; Status.Speed = status[6]; // MSB Status.Speed *= 256; Status.Speed += status[5]; var Speed = Status.Speed/GEAR_RATIO; Status.Speed = (int) Speed; ... } public void Read() { while (serialPort1 != null) { try { serialPort1.Read(Status, 0, 1); if (Status[0] != StartCharacter[0]) continue; serialPort1.Read(Status, 1, 1); if (Status[1] != StartCharacter[1]) continue; serialPort1.Read(Status, 2, 1); if (Status[2] != (int)Command.GetStatus) continue; serialPort1.Read(Status, 3, 1); ... statusMutex.WaitOne(); ProcessStatus(Status); Status.update = true; statusMutex.ReleaseMutex(); } catch (Exception e) { Console.WriteLine(@"ERROR! Read() " + e); } } } public void GetStatus() { const int parameterLength = 0; // For GetStatus statusMutex.WaitOne(); Status.update = false; statusMutex.ReleaseMutex(); commandMutex.WaitOne(); if (!SendCommand(Command.GetStatus, parameterLength)) { Console.WriteLine(@"ERROR! SendCommand(GetStatus)"); } commandMutex.ReleaseMutex(); } private void UpdateGui(object x) { try { Invoke((MethodInvoker)delegate { Text = DateTime.Now.ToLongTimeString(); statusMutex.WaitOne(); if (Status.update) { if (Status.Speed > progressBarSpeed.Maximum) { Status.Speed = progressBarSpeed.Maximum; } progressBarSpeed.Value = Status.Speed; labelSpeed.Text = Status.Speed + RPM; ... } else { labelWarning.Text = LOST_COMMUNICATIONS; labelStatus.Text = LOST_COMMUNICATIONS; labelWarning.Visible = true; } statusMutex.ReleaseMutex(); GetStatus(); }); } catch (Exception e) { Console.WriteLine(@"ERROR! UpdateGui() " + e); } } }

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How to reduce Entity Framework 4 query compile time?

- by Rup

Summary: We're having problems with EF4 query compilation times of 12+ seconds. Cached queries will only get us so far; are there any ways we can actually reduce the compilation time? Is there anything we might be doing wrong we can look for? Thanks! We have an EF4 model which is exposed over the WCF services. For each of our entity types we expose a method to fetch and return the whole entity for display / edit including a number of referenced child objects. For one particular entity we have to .Include() 31 tables / sub-tables to return all relevant data. Unfortunately this makes the EF query compilation prohibitively slow: it takes 12-15 seconds to compile and builds a 7,800-line, 300K query. This is the back-end of a web UI which will need to be snappier than that. Is there anything we can do to improve this? We can CompiledQuery.Compile this - that doesn't do any work until first use and so helps the second and subsequent executions but our customer is nervous that the first usage shouldn't be slow either. Similarly if the IIS app pool hosting the web service gets recycled we'll lose the cached plan, although we can increase lifetimes to minimise this. Also I can't see a way to precompile this ahead of time and / or to serialise out the EF compiled query cache (short of reflection tricks). The CompiledQuery object only contains a GUID reference into the cache so it's the cache we really care about. (Writing this out it occurs to me I can kick off something in the background from app_startup to execute all queries to get them compiled - is that safe?) However even if we do solve that problem, we build up our search queries dynamically with LINQ-to-Entities clauses based on which parameters we're searching on: I don't think the SQL generator does a good enough job that we can move all that logic into the SQL layer so I don't think we can pre-compile our search queries. This is less serious because the search data results use fewer tables and so it's only 3-4 seconds compile not 12-15 but the customer thinks that still won't really be acceptable to end-users. So we really need to reduce the query compilation time somehow. Any ideas? Profiling points to ELinqQueryState.GetExecutionPlan as the place to start and I have attempted to step into that but without the real .NET 4 source available I couldn't get very far, and the source generated by Reflector won't let me step into some functions or set breakpoints in them. The project was upgraded from .NET 3.5 so I have tried regenerating the EDMX from scratch in EF4 in case there was something wrong with it but that didn't help. I have tried the EFProf utility advertised here but it doesn't look like it would help with this. My large query crashes its data collector anyway. I have run the generated query through SQL performance tuning and it already has 100% index usage. I can't see anything wrong with the database that would cause the query generator problems. Is there something O(n^2) in the execution plan compiler - is breaking this down into blocks of separate data loads rather than all 32 tables at once likely to help? Setting EF to lazy-load didn't help. I've bought the pre-release O'Reilly Julie Lerman EF4 book but I can't find anything in there to help beyond 'compile your queries'. I don't understand why it's taking 12-15 seconds to generate a single select across 32 tables so I'm optimistic there's some scope for improvement! Thanks for any suggestions! We're running against SQL Server 2008 in case that matters and XP / 7 / server 2008 R2 using RTM VS2010.

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Find optimal/good-enough strategy and AI for the game 'Proximity'?

- by smci

'Proximity' is a strategy game of territorial domination similar to Othello, Go and Risk. Two players, uses a 10x12 hex grid. Game invented by Brian Cable in 2007. Seems to be a worthy game for discussing a) optimal algorithm then b) how to build an AI. Strategies are going to be probabilistic or heuristic-based, due to the randomness factor, and the insane branching factor (20^120). So it will be kind of hard to compare objectively. A compute time limit of 5s per turn seems reasonable. Game: Flash version here and many copies elsewhere on the web Rules: here Object: to have control of the most armies after all tiles have been placed. Each turn you received a randomly numbered tile (value between 1 and 20 armies) to place on any vacant board space. If this tile is adjacent to any ally tiles, it will strengthen each tile's defenses +1 (up to a max value of 20). If it is adjacent to any enemy tiles, it will take control over them if its number is higher than the number on the enemy tile. Thoughts on strategy: Here are some initial thoughts; setting the computer AI to Expert will probably teach a lot: minimizing your perimeter seems to be a good strategy, to prevent flips and minimize worst-case damage like in Go, leaving holes inside your formation is lethal, only more so with the hex grid because you can lose armies on up to 6 squares in one move low-numbered tiles are a liability, so place them away from your main territory, near the board edges and scattered. You can also use low-numbered tiles to plug holes in your formation, or make small gains along the perimeter which the opponent will not tend to bother attacking. a triangle formation of three pieces is strong since they mutually reinforce, and also reduce the perimeter Each tile can be flipped at most 6 times, i.e. when its neighbor tiles are occupied. Control of a formation can flow back and forth. Sometimes you lose part of a formation and plug any holes to render that part of the board 'dead' and lock in your territory/ prevent further losses. Low-numbered tiles are obvious-but-low-valued liabilities, but high-numbered tiles can be bigger liabilities if they get flipped (which is harder). One lucky play with a 20-army tile can cause a swing of 200 (from +100 to -100 armies). So tile placement will have both offensive and defensive considerations. Comment 1,2,4 seem to resemble a minimax strategy where we minimize the maximum expected possible loss (modified by some probabilistic consideration of the value ß the opponent can get from 1..20 i.e. a structure which can only be flipped by a ß=20 tile is 'nearly impregnable'.) I'm not clear what the implications of comments 3,5,6 are for optimal strategy. Interested in comments from Go, Chess or Othello players. (The sequel ProximityHD for XBox Live, allows 4-player -cooperative or -competitive local multiplayer increases the branching factor since you now have 5 tiles in your hand at any given time, of which you can only play one. Reinforcement of ally tiles is increased to +2 per ally.)

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highlight navigation PHP

- by Kira

I've launched a website a while back and successfully used Javascript + CSS to highlight the current page on the navigation. However, it is not working in Safari and it does not validate well, when using Javascript, so I decided to have PHP assign the CSS id to the HTML elements. So far, it works fine, compared to the other times where there was two of each link displayed, when it was attempted in PHP. My problem is that all links look normal and the CSS property is not applied. I have a feeling that it has to do with my PHP code, but I'm not certain. The site address is here As for the PHP code, here it is: <?php echo('<li>Main'); echo('<ul>'); if ($page=="home") { echo('<li><a id="current" href="index.shtml">Home</a></li>'); } else { echo('<li><a href="index.shtml">Home</a></li>'); } if ($page=="faq") { echo('<li><a id="current" href="faq.shtml">FAQ</a></li>'); } else { echo('<li><a href="faq.shtml">FAQ</a></li>'); } if ($page=="about") { echo('<li><a id="current" href="about.shtml">About Bryce</a></li>'); } else { echo('<li><a href="about.shtml">About Bryce</a></li>'); } echo('<li><a href="contact.php">Contact Bryce</a></li>'); if ($page=="sign guestbook") { echo('<li><a id="current" href="sign.shtml">Sign Guestbook</a></li>'); } else { echo('<li><a href="sign.shtml">Sign Guestbook</a></li>'); } if ($page=="view guestbook") { echo('<li><a id="current" href="view.shtml">View Guestbook</a></li>'); } else { echo('<li><a href="view.shtml">View Guestbook</a></li>'); } echo('</ul>'); echo('</li>'); echo('<li>Info'); echo('<ul>'); if ($page=="projects") { echo('<li><a id="current" href="projects.shtml">Projects</a></li>'); } else { echo('<li><a href="projects.shtml">Projects</a></li>'); } if ($page=="books") { echo('<li><a id="current" href="books.shtml">Books</a></li>'); } else { echo('<li><a href="books.shtml">Books</a></li>'); } echo('</ul>'); echo('</li>'); echo('<li>Misc.'); echo('<ul>'); if ($page=="cover designs") { echo('<li><a id="current" href="coverdesigns.shtml">Cover Designs</a></li>'); } else { echo('<li><a href="coverdesigns.shtml">Cover Designs</a></li>'); } echo('<li><a target="_blank" href="http://www.lulu.com/brycecampbellsbooks">Lulu Store</a></li>'); echo('<li><a href="rss/">RSS</a></li>'); echo('</ul>'); echo('</li>'); ?> In order to give you guys an idea of what the highlighting effect should look like, here is the CSS that is supposed to be applied to the current page: #current { font-style: italic; text-decoration: none; color: #000000; } When looking up what I was doing wrong, it told me that I was implementing it right, but it does not seem that the PHP is getting the values.

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Temporary "Backup" of SharePoint Content During Feature and Solution Deployment

- by ccomet

I need to decide on a method for storing a subset of the content in a SharePoint site, so that when I delete and recreate certain lists as part of a feature activation, I can re-insert all of this content back where it should belong. I have an idea myself, but I don't know if it's the only method and more importantly, the right method. My client has me creating a SharePoint system for them to communicate with their clients. The business process has maybe 5 stages in it (maybe it's more, I don't even know because they don't tell me everything), and the current system I've written over the past months is maybe 2 stages through. This meets our deadline of completing those systems by Monday next week... but at that point my client is planning on making the site live from that point. In effect, their work with their clients will be running parallel with my work for them. As I complete my own work on a separate test server, I'll push each following stage of the process onto the live server. Scheduled downtimes during non-business times (like a weekend) will be available for me to perform these pushes. Keeping pace so that my development is faster than the actual business process is my own problem and off-topic... so let's get back to the problem I stated at the start of this post. In this system, we have sets of features which will create lists for their associated content types and field types when activated, and delete these lists when the feature is deactivated. Most updates don't need to deactivate and reactivate these features, such as workflow changes, custom actions, custom forms, and similar ilk. But there are some parts which do require this. On my test server, it's okay for me to obliterate lists, but once the site is live and there's real correspondence data, it's absolutely unacceptable to do this. So when I need to implement a new change in functionality, I need to be able to store the currently present data in several lists, deactivate the feature, reactivate the feature, and restore all of this data. Perhaps I have hoist myself by my own petard with the feature system I implemented. Unfortunately, the necessity to later on make several of these "project sites" meant I had to do a lot of my code with the concept of "Can be deployed repeatedly" in mind. My current plan is to run through lists and libraries which will be affected by the particular feature that is to be reset. Files and all of their versions will be saved in a directory on the server. Then, a set of text files will be used to store all of the important field values for the items. This includes a lot of cross-list reference lookups that will need to be maintained, but that's simple enough. Then, I deactivate the feature, deploy the new solution, and reactivate the feature. We upload all of the files in the order specified by their versions and update them with the stored fields for those versions, so that we retain the version structure. As each one is first uploaded, the new ID is picked out, and all relevant lookups in the rest of the files are updated (in some manner that I make sure I don't re-update it later with an incorrect value, of course). After that, we run through all the rest of the items in the order most conducive to keeping the relational data correct. This roughly summarizes what my current plan is. To my advantage, there are no long running workflows in the system that will be affected by this, so there's nothing I will have to worry about making sure nothing is "still running" when I do this stuff. I don't really know all the cons of this approach... I can imagine they're quite hefty. But I'm unsure what other choices I even have, and my searches haven't turned up anything. Is there anyone who can think of a better idea? Or will anyone just tell me that I really have no other choice? Thanks in advance!

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