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• Limiting TCP sends with a "to-be-sent" queue and other design issues.

  - by Poni

  Hello all! This question is the result of two other questions I've asked in the last few days. I'm creating a new question because I think it's related to the "next step" in my understanding of how to control the flow of my send/receive, something I didn't get a full answer to yet. The other related questions are: http://stackoverflow.com/questions/3028376/an-iocp-documentation-interpretation-question-buffer-ownership-ambiguity http://stackoverflow.com/questions/3028998/non-blocking-tcp-buffer-issues In summary, I'm using Windows I/O Completion Ports. I have several threads that process notifications from the completion port. I believe the question is platform-independent and would have the same answer as if to do the same thing on a *nix, *BSD, Solaris system. So, I need to have my own flow control system. Fine. So I send send and send, a lot. How do I know when to start queueing the sends, as the receiver side is limited to X amount? Let's take an example (closest thing to my question): FTP protocol. I have two servers; One is on a 100Mb link and the other is on a 10Mb link. I order the 100Mb one to send to the other one (the 10Mb linked one) a 1GB file. It finishes with an average transfer rate of 1.25MB/s. How did the sender (the 100Mb linked one) knew when to hold the sending, so the slower one wouldn't be flooded? Another way to ask this: Can I get a "hold-your-sendings" notification from the remote side? Is it built-in in TCP or the so called "reliable network protocol" needs me to do so? Again, I have a loop with many sends to a remote server, and at some point, within that loop I'll have to determine if I should queue that send or I can pass it on to the transport layer (TCP). How do I do that? What would you do? Of course that when I get a completion notification from IOCP that the send was done I'll issue other pending sends, that's clear. Another design question related to this: Since I am to use a custom buffers with a send queue, and these buffers are being freed to be reused (thus not using the "delete" keyword) when a "send-done" notification has been arrived, I'll have to use a mutual exlusion on that buffer pool. Using a mutex slows things down, so I've been thinking; Why not have each thread have its own buffers pool, thus accessing it , at least when getting the required buffers for a send operation, will require no mutex, because it belongs to that thread only. The buffers pool is located at the thread local storage (TLS) level. No mutual pool implies no lock needed, implies faster operations BUT also implies more memory used by the app, because even if one thread already allocated 1000 buffers, the other one that is sending right now and need 1000 buffers to send something will need to allocated these to its own. This is a long question and I hope none got hurt (: Thank you all!

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• Picking good first estimates for Goldschmidt division

  - by Mads Elvheim

  I'm calculating fixedpoint reciprocals in Q22.10 with Goldschmidt division for use in my software rasterizer on ARM. This is done by just setting the nominator to 1, i.e the nominator becomes the scalar on the first iteration. To be honest, I'm kind of following the wikipedia algorithm blindly here. The article says that if the denominator is scaled in the half-open range (0.5, 1.0], a good first estimate can be based on the denominator alone: Let F be the estimated scalar and D be the denominator, then F = 2 - D. But when doing this, I lose a lot of precision. Say if I want to find the reciprocal of 512.00002f. In order to scale the number down, I lose 10 bits of precision in the fraction part, which is shifted out. So, my questions are: Is there a way to pick a better estimate which does not require normalization? Also, is it possible to pre-calculate the first estimates so the series converges faster? Right now, it converges after the 4th iteration on average. On ARM this is about ~50 cycles worst case, and that's not taking emulation of clz/bsr into account, nor memory lookups. Here is my testcase. Note: The software implementation of clz on line 13 is from my post here. You can replace it with an intrinsic if you want. #include <stdio.h> #include <stdint.h> const unsigned int BASE = 22ULL; static unsigned int divfp(unsigned int val, int* iter) { /* Nominator, denominator, estimate scalar and previous denominator */ unsigned long long N,D,F, DPREV; int bitpos; *iter = 1; D = val; /* Get the shift amount + is right-shift, - is left-shift. */ bitpos = 31 - clz(val) - BASE; /* Normalize into the half-range (0.5, 1.0] */ if(0 < bitpos) D >>= bitpos; else D <<= (-bitpos); /* (FNi / FDi) == (FN(i+1) / FD(i+1)) */ /* F = 2 - D */ F = (2ULL<<BASE) - D; /* N = F for the first iteration, because the nominator is simply 1. So don't waste a 64-bit UMULL on a multiply with 1 */ N = F; D = ((unsigned long long)D*F)>>BASE; while(1){ DPREV = D; F = (2<<(BASE)) - D; D = ((unsigned long long)D*F)>>BASE; /* Bail when we get the same value for two denominators in a row. This means that the error is too small to make any further progress. */ if(D == DPREV) break; N = ((unsigned long long)N*F)>>BASE; *iter = *iter + 1; } if(0 < bitpos) N >>= bitpos; else N <<= (-bitpos); return N; } int main(int argc, char* argv[]) { double fv, fa; int iter; unsigned int D, result; sscanf(argv[1], "%lf", &fv); D = fv*(double)(1<<BASE); result = divfp(D, &iter); fa = (double)result / (double)(1UL << BASE); printf("Value: %8.8lf 1/value: %8.8lf FP value: 0x%.8X\n", fv, fa, result); printf("iteration: %d\n",iter); return 0; }

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• trie reg exp parse step over char and continue

  - by forest.peterson

  Setup: 1) a string trie database formed from linked nodes and a vector array linking to the next node terminating in a leaf, 2) a recursive regular expression function that if A) char '*' continues down all paths until string length limit is reached, then continues down remaining string paths if valid, and B) char '?' continues down all paths for 1 char and then continues down remaining string paths if valid. 3) after reg expression the candidate strings are measured for edit distance against the 'try' string. Problem: the reg expression works fine for adding chars or swapping ? for a char but if the remaining string has an error then there is not a valid path to a terminating leaf; making the matching function redundant. I tried adding a 'step-over' ? char if the end of the node vector was reached and then followed every path of that node - allowing this step-over only once; resulted in a memory exception; I cannot find logically why it is accessing the vector out of range - bactracking? Questions: 1) how can the regular expression step over an invalid char and continue with the path? 2) why is swapping the 'sticking' char for '?' resulting in an overflow? Function: void Ontology::matchRegExpHelper(nodeT *w, string inWild, Set<string> &matchSet, string out, int level, int pos, int stepover) { if (inWild=="") { matchSet.add(out); } else { if (w->alpha.size() == pos) { int testLength = out.length() + inWild.length(); if (stepover == 0 && matchSet.size() == 0 && out.length() > 8 && testLength == tokenLength) {//candidate generator inWild[0] = '?'; matchRegExpHelper(w, inWild, matchSet, out, level, 0, stepover+1); } else return; //giveup on this path } if (inWild[0] == '?' || (inWild[0] == '*' && (out.length() + inWild.length() ) == level ) ) { //wild matchRegExpHelper(w->alpha[pos].next, inWild.substr(1), matchSet, out+w->alpha[pos].letter, level, 0, stepover);//follow path -> if ontology is full, treat '*' like a '?' } else if (inWild[0] == '*') matchRegExpHelper(w->alpha[pos].next, '*'+inWild.substr(1), matchSet, out+w->alpha[pos].letter, level, 0, stepover); //keep adding chars if (inWild[0] == w->alpha[pos].letter) //follow self matchRegExpHelper(w->alpha[pos].next, inWild.substr(1), matchSet, out+w->alpha[pos].letter, level, 0, stepover); //follow char matchRegExpHelper(w, inWild, matchSet, out, level, pos+1, stepover);//check next path } } Error Message: +str "Attempt to access index 1 in a vector of size 1." std::basic_string<char,std::char_traits<char>,std::allocator<char> > +err {msg="Attempt to access index 1 in a vector of size 1." } ErrorException Note: this function works fine for hundreds of test strings with '*' wilds if the extra stepover gate is not used Semi-Solved: I place a pos < w->alpha.size() condition on each path that calls w->alpha[pos]... - this prevented the backtrack calls from attempting to access the vector with an out of bounds index value. Still have other issues to work out - it loops infinitely adding the ? and backtracking to remove it, then repeat. But, moving forward now. Revised question: why during backtracking is the position index accumulating and/or not deincrementing - so at somepoint it calls w->alpha[pos]... with an invalid position that is either remaining from the next node or somehow incremented pos+1 when passing upward?

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• Algorithm for dragging objects on a fixed grid

  - by FlyingStreudel

  Hello, I am working on a program for the mapping and playing of the popular tabletop game D&D :D Right now I am working on getting the basic functionality like dragging UI elements around, snapping to the grid and checking for collisions. Right now every object when released from the mouse immediately snaps to the nearest grid point. This causes an issue when something like a player object snaps to a grid point that has a wall -or other- adjacent. So essentially when the player is dropped they wind up with some of the wall covering them. This is fine and working as intended, however the problem is that now my collision detection is tripped whenever you try to move this player because its sitting underneath a wall and because of this you cant drag the player anymore. Here is the relevant code: void UIObj_MouseMove(object sender, MouseEventArgs e) { blocked = false; if (dragging) { foreach (UIElement o in ((Floor)Parent).Children) { if (o.GetType() != GetType() && o.GetType().BaseType == typeof(UIObj) && Math.Sqrt(Math.Pow(((UIObj)o).cX - cX, 2) + Math.Pow(((UIObj)o).cY - cY, 2)) < Math.Max(r.Height + ((UIObj)o).r.Height, r.Width + ((UIObj)o).r.Width)) { double Y = e.GetPosition((Floor)Parent).Y; double X = e.GetPosition((Floor)Parent).X; Geometry newRect = new RectangleGeometry(new Rect(Margin.Left + (X - prevX), Margin.Top + (Y - prevY), Margin.Right + (X - prevX), Margin.Bottom + (Y - prevY))); GeometryHitTestParameters ghtp = new GeometryHitTestParameters(newRect); VisualTreeHelper.HitTest(o, null, new HitTestResultCallback(MyHitTestResultCallback), ghtp); } } if (!blocked) { Margin = new Thickness(Margin.Left + (e.GetPosition((Floor)Parent).X - prevX), Margin.Top + (e.GetPosition((Floor)Parent).Y - prevY), Margin.Right + (e.GetPosition((Floor)Parent).X - prevX), Margin.Bottom + (e.GetPosition((Floor)Parent).Y - prevY)); InvalidateVisual(); } prevX = e.GetPosition((Floor)Parent).X; prevY = e.GetPosition((Floor)Parent).Y; cX = Margin.Left + r.Width / 2; cY = Margin.Top + r.Height / 2; } } internal virtual void SnapToGrid() { double xPos = Margin.Left; double yPos = Margin.Top; double xMarg = xPos % ((Floor)Parent).cellDim; double yMarg = yPos % ((Floor)Parent).cellDim; if (xMarg < ((Floor)Parent).cellDim / 2) { if (yMarg < ((Floor)Parent).cellDim / 2) { Margin = new Thickness(xPos - xMarg, yPos - yMarg, xPos - xMarg + r.Width, yPos - yMarg + r.Height); } else { Margin = new Thickness(xPos - xMarg, yPos - yMarg + ((Floor)Parent).cellDim, xPos - xMarg + r.Width, yPos - yMarg + ((Floor)Parent).cellDim + r.Height); } } else { if (yMarg < ((Floor)Parent).cellDim / 2) { Margin = new Thickness(xPos - xMarg + ((Floor)Parent).cellDim, yPos - yMarg, xPos - xMarg + ((Floor)Parent).cellDim + r.Width, yPos - yMarg + r.Height); } else { Margin = new Thickness(xPos - xMarg + ((Floor)Parent).cellDim, yPos - yMarg + ((Floor)Parent).cellDim, xPos - xMarg + ((Floor)Parent).cellDim + r.Width, yPos - yMarg + ((Floor)Parent).cellDim + r.Height); } } } Essentially I am looking for a simple way to modify the existing code to allow the movement of a UI element that has another one sitting on top of it. Thanks!

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• ValidationProperty not returning entered value for textbox in custom ontrol

  - by nat

  hi I have a custom control, (relevant code at the bottom) it consists of some text/links and a hidden textbox (rather than a hidden input). when rendered, the user via another dialog and some JS sets the value of the textbox to an integer and clicks submit on the form. i am trying to assure that the user has entered a number (via the JS) and that the textbox is not still set to its default of "0" the requiredfieldvalidator works just fine, if i dont change the value it spots it on the client and fills the validation summary on the page with the appropriate message. unfortunately when i do fill the textbox, the validator also rejests the post as the controls textbox text value is still set to "0", even though on the form it has changed. clearly i am doing something wrong.. but cant work out what it is? could someone enlighten me please, this is driving me potty if i step through the code, when the get of the mediaidtext is hit,the findcontrol finds does not the textbox, if i inspect the controls collection however i can find the textbox, but its value is still "0" it also seems that when findcontrol is called, the createchildcontrols is called again - thus resetting the value back to "0" there.. ! how can i ever assure the control realises that the textbox value has changed? many thanks code below nat [ValidationProperty("MediaIdText")] public class MediaLibraryFileControl: CompositeControl { private int mediaId = 0; public int MediaId { get { return mediaId; } set { mediaId = value; } } public string MediaIdText { get { string txt = "0"; Control ctrl = this.FindControl(this.UniqueID+ "_hidden"); try { txt = ((TextBox)ctrl).Text; MediaId = Convert.ToInt32(txt); } catch { MediaId = 0; } return txt; } } protected override void CreateChildControls() { this.Controls.Add(new LiteralControl("<span>")); this.Controls.Add(new LiteralControl("<span id=\"" + TextControlName + "\">" + getMediaDetails() + "</span>")); TextBox tb = new TextBox(); tb.Text = this.MediaId.ToString(); tb.ID = this.UniqueID + "_hidden"; tb.CssClass = "hidden"; this.Controls.Add(tb); if (Select == true) { this.Controls.Add(new LiteralControl(string.Format("&nbsp;[<a href=\"javascript:{0}(this,'{1}','{2}')\" class=\"select\">{3}</a>]", dialog, this.UniqueID, this.categoryId, "select"))); this.Controls.Add(new LiteralControl(string.Format("&nbsp;[<a href=\"javascript:{0}(this,'{1}')\" class=\"select\">{2}</a>]", clearDialog, this.ID, "clear"))); } this.Controls.Add(new LiteralControl("</span>")); } protected virtual string getMediaDetails() { //... return String.Empty; } } this is the code adding the validationcontrol the editcontrol is the instance of the control above public override Control RenderValidationControl(Control editControl) { Control ctrl = new PlaceHolder(); RequiredFieldValidator req = new RequiredFieldValidator(); req.ID = editControl.ClientID + "_validator"; req.ControlToValidate = editControl.ID; req.Display = ValidatorDisplay.None; req.InitialValue = "0"; req.EnableClientScript = false; req.ErrorMessage = "control cannot be blank"; ctrl.Controls.Add(req); return ctrl; }

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• Getting Segmentation Fault in C++, but why?

  - by Carlos

  I am getting segmentation fault in this code but i cant figure out why. I know a segmentation fault happens when a pointer is NULL, or when it points to a random memory address. #include <iostream> #include <fstream> #include <cmath> using namespace std; //**************************** CLASS ******************************* class Database { struct data{ string city; float latitude, longitude; data *link; }*p; public: Database(); void display(); void add(string cityName, float lat, float lon); private: string cityName; float lat, lon; }; //************************** CLASS METHODS ************************** Database::Database() { p = NULL; } void Database::add(string cityName, float lat, float lon){ data *q, *t; if(p == NULL){ p = new data; p -> city = cityName; p -> latitude = lat; p -> longitude = lon; p -> link = NULL; } else{ q = p; while(q -> link != NULL){ q = q -> link; } t = new data; t -> city = cityName; t -> latitude = lat; t -> longitude = lon; q -> link = t; } } void Database::display() { data *q; cout<<endl; for( q = p ; q != NULL ; q = q->link ) cout << endl << q -> city; } //***************************** MAIN ******************************* //*** INITIALIZATION *** Database D; void loadDatabase(); //****** VARIABLES ***** //******* PROGRAM ****** int main() { loadDatabase(); D.display(); } void loadDatabase() { int i = 0; string cityName; float lat, lon; fstream city; city.open("city.txt", ios::in); fstream latitude; latitude.open("lat.txt", ios::in); fstream longitude; longitude.open("lon.txt", ios::in); while(!city.eof()){ //************************************ city >> cityName; //* * latitude >> lat; //Here is where i think is the problem longitude >> lon; //* * D.add(cityName, lat, lon); //************************************ } city.close(); latitude.close(); longitude.close(); } This is the error am actually getting in console

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• Foolishness Check: PHP Class finds Class file but not Class in the file.

  - by Daniel Bingham

  I'm at a loss here. I've defined an abstract superclass in one file and a subclass in another. I have required the super-classes file and the stack trace reports to find an include it. However, it then returns an error when it hits the 'extends' line: Fatal error: Class 'HTMLBuilder' not found in View/Markup/HTML/HTML4.01/HTML4_01Builder.php on line 7. I had this working with another class tree that uses factories a moment ago. I just added the builder layer in between the factories and the consumer. The factory layer looked almost exactly the same in terms of includes and dependencies. So that makes me think I must have done something silly that's causes the HTMLBuilder.php file to not be included correctly or interpreted correctly or some such. Here's the full stack trace (paths slightly altered): # Time Memory Function Location 1 0.0001 53904 {main}( ) ../index.php:0 2 0.0002 67600 require_once( 'View/Page.php' ) ../index.php:3 3 0.0003 75444 require_once( 'View/Sections/SectionFactory.php' ) ../Page.php:4 4 0.0003 81152 require_once( 'View/Sections/HTML/HTMLSectionFactory.php' ) ../SectionFactory.php:3 5 0.0004 92108 require_once( 'View/Sections/HTML/HTMLTitlebarSection.php' ) ../HTMLSectionFactory.php:5 6 0.0005 99716 require_once( 'View/Markup/HTML/HTMLBuilder.php' ) ../HTMLTitlebarSection.php:3 7 0.0005 103580 require_once( 'View/Markup/MarkupBuilder.php' ) ../HTMLBuilder.php:3 8 0.0006 124120 require_once( 'View/Markup/HTML/HTML4.01/HTML4_01Builder.php' ) ../MarkupBuilder.php:3 Here's the code in question: Parent class (View/Markup/HTML/HTMLBuilder.php): <?php require_once('View/Markup/MarkupBuilder.php'); abstract class HTMLBuilder extends MarkupBuilder { public abstract function getLink($text, $href); public abstract function getImage($src, $alt); public abstract function getDivision($id, array $classes=NULL, array $children=NULL); public abstract function getParagraph($text, array $classes=NULL, $id=NULL); } ?> Child Class, (View/Markup/HTML/HTML4.01/HTML4_01Builder.php): <?php require_once('HTML4_01Factory.php'); require_once('View/Markup/HTML/HTMLBuilder.php'); class HTML4_01Builder extends HTMLBuilder { private $factory; public function __construct() { $this->factory = new HTML4_01Factory(); } public function getLink($href, $text) { $link = $this->factory->getA(); $link->addAttribute('href', $href); $link->addChild($this->factory->getText($text)); return $link; } public function getImage($src, $alt) { $image = $this->factory->getImg(); $image->addAttribute('src', $src); $image->addAttribute('alt', $alt); return $image; } public function getDivision($id, array $classes=NULL, array $children=NULL) { $div = $this->factory->getDiv(); $div->setID($id); if(!empty($classes)) { $div->addClasses($classes); } if(!empty($children)) { $div->addChildren($children); } return $div; } public function getParagraph($text, array $classes=NULL, $id=NULL) { $p = $this->factory->getP(); $p->addChild($this->factory->getText($text)); if(!empty($classes)) { $p->addClasses($classes); } if(!empty($id)) { $p->setID($id); } return $p; } } ?> I would appreciate any and all ideas. I'm at a complete loss here as to what is going wrong. I'm sure it's something stupid I just can't see...

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• Strange behaviour when simply adding strings in Lazarus - FreePascal

  - by linkcharger

  The program has several "encryption" algorithms. This one should blockwise reverse the input. "He|ll|o " becomes "o |ll|He" (block length of 2). I add two strings, in this case appending the result string to the current "block" string and making that the result. When I add the result first and then the block it works fine and gives me back the original string. But when i try to reverse the order it just gives me the the last "block". Several other functions that are used for "rotation" are above. //amount of blocks function amBl(i1:integer;i2:integer):integer; begin if (i1 mod i2) <> 0 then result := (i1 div i2) else result := (i1 div i2) - 1; end; //calculation of block length function calcBl(keyStr:string):integer; var i:integer; begin result := 0; for i := 1 to Length(keyStr) do begin result := (result + ord(keyStr[i])) mod 5; result := result + 2; end; end; //desperate try to add strings function append(s1,s2:string):string; begin insert(s2,s1,Length(s1)+1); result := s1; end; function rotation(inStr,keyStr:string):string; var //array of chars -> string block,temp:string; //position in block variable posB:integer; //block length and block count variable bl, bc:integer; //null character as placeholder n : ansiChar; begin //calculating block length 2..6 bl := calcBl(keyStr); setLength(block,bl); result := ''; temp := ''; {n := #00;} for bc := 0 to amBl(Length(inStr),bl) do begin //filling block with chars starting from back of virtual block (in inStr) for posB := 1 to bl do begin block[posB] := inStr[bc * bl + posB]; {if inStr[bc * bl + posB] = ' ' then block[posB] := n;} end; //adding the block in front of the existing result string temp := result; result := block + temp; //result := append(block,temp); //result := concat(block,temp); end; end; (full code http://pastebin.com/6Uarerhk) After all the loops "result" has the right value, but in the last step (between "result := block + temp" and the "end;" of the function) "block" replaces the content of "result" with itself completely, it doesn't add result at the end anymore. And as you can see I even used a temp variable to try to work around that.. doesnt change anything though.

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• multple inner joins 3 or more crashes mysql server 5.1.30 opensolaris

  - by user331849

  when doing simple query on 4 inner joined tables, the server crashes with the output below appearing in the the mysql .err file. eg. select * from table1 inner join table2 on table1.a = table2.a and table1.b = table2.b inner join table3 on table2.a = table3.a and table2.c = table3.c inner join table4 on table3.a = table4.a and table3.d = table4.d If i remove one of the tables it executes fine. Likewise if I remove a different table, it executes fine. Though all tables have been checked anyway, this would suggest that it is not a problem specifically with one of the tables. mysql.err trace: 100503 18:13:19 - mysqld got signal 11 ; This could be because you hit a bug. It is also possible that this binary or one of the libraries it was linked against is corrupt, improperly built, or misconfigured. This error can also be caused by malfunctioning hardware. We will try our best to scrape up some info that will hopefully help diagnose the problem, but since we have already crashed, something is definitely wrong and this may fail. key_buffer_size=1572864000 read_buffer_size=2097152 max_used_connections=11 max_threads=151 threads_connected=10 It is possible that mysqld could use up to key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 2155437 K bytes of memory Hope that's ok; if not, decrease some variables in the equation. thd: 0x72febda8 Attempting backtrace. You can use the following information to find out where mysqld died. If you see no messages after this, something went terribly wrong... stack_bottom = fe07efb0 thread_stack 0x40000 Trying to get some variables. Some pointers may be invalid and cause the dump to abort... thd-query at be1021f0 = explain select * from business inner join timetable on business.id = timetable.business_id inner join timetableentry on timetable.business_id = timetableentry.business_id and timetable.kid = timetableentry.parent inner join staff on timetable.business_id = staff.business_id and timetable.staf f_person = staff.kid where business.id = '3050bb04fda41df64a9c1c149150026c' thd-thread_id=9 thd-killed=NOT_KILLED The manual page at http://dev.mysql.com/doc/mysql/en/crashing.html contains information that should help you find out what is causing the crash. 100503 18:13:19 mysqld_safe mysqld restarted 100503 18:13:20 InnoDB: Failed to set DIRECTIO_ON on file ./ibdata1: OPEN: Inap propriate ioctl for device, continuing anyway 100503 18:13:20 InnoDB: Failed to set DIRECTIO_ON on file ./ibdata1: OPEN: Inap propriate ioctl for device, continuing anyway InnoDB: The log sequence number in ibdata files does not match InnoDB: the log sequence number in the ib_logfiles! 100503 18:13:20 InnoDB: Database was not shut down normally! InnoDB: Starting crash recovery. InnoDB: Reading tablespace information from the .ibd files... InnoDB: Restoring possible half-written data pages from the doublewrite InnoDB: buffer... InnoDB: Last MySQL binlog file position 0 2731, file name ./mysql-bin.000093 100503 18:13:20 InnoDB: Started; log sequence number 0 2650338426 100503 18:13:20 [Note] Recovering after a crash using mysql-bin 100503 18:13:20 [Note] Starting crash recovery... 100503 18:13:20 [Note] Crash recovery finished. This on opensolaris SunOS 5.11 snv_111b i86pc i386 i86pc Mysql 5.1.30 Here is a snippet from the my.cnf file: key_buffer = 1500M max_allowed_packet = 1M thread_stack = 256K thread_cache_size = 8 sort_buffer_size = 2M read_buffer_size = 2M read_rnd_buffer_size = 8M table_cache = 512 tmp_table_size = 400M max_heap_table_size = 64M query_cache_limit = 20M query_cache_size = 200M Is this a bug or a configuration issue?

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• extensible database design: automatic ALTER TABLE or serialize() field BLOB ?

  - by mario

  I want an adaptable database scheme. But still use a simple table data gateway in my application, where I just pass an $data[] array for storing. The basic columns are settled in the initial table scheme. There will however arise a couple of meta fields later (ca 10-20). I want some flexibility there and not adapt the database manually each time, or -worse- change the application logic just because of new fields. So now there are two options which seem workable yet not overkill. But I'm not sure about the scalability or database drawbacks. (1) Automatic ALTER TABLE. Whenever the $data array is to be saved, the keys are compared against the current database columns. New columns get defined before the $data is INSERTed into the table. Actually seems simple enough in test code: function save($data, $table="forum") { // columns if ($new_fields = array_diff(array_keys($data), known_fields($table))) { extend_schema($table, $new_fields, $data); } // save $columns = implode("`, `", array_keys($data)); $qm = str_repeat(",?", count(array_keys($data)) - 1); echo ("INSERT INTO `$table` (`$columns`) VALUES (?$qm);"); function known_fields($table) { return unserialize(@file_get_contents("db:$table")) ?: array("id"); function extend_schema($table, $new_fields, $data) { foreach ($new_fields as $field) { echo("ALTER TABLE `$table` ADD COLUMN `$field` VARCHAR;"); Since it is mostly meta information fields, adding them just as VARCHAR seems sufficient. Nobody will query by them anyway. So the database is really just used as storage here. However, while I might want to add a lot of new $data fields on the go, they will not always be populated. (2) serialize() fields into BLOB. Any new/extraneous meta fields could be opaque to the database. Simply sorting out the virtual fields from the real database columns is simple. And the meta fields can just be serialize()d into a blob/text field then: function ext_save($data, $table="forum") { $db_fields = array("id", "content", "flags", "ext"); // disjoin foreach (array_diff(array_keys($data),$db_fields) as $key) { $data["ext"][$key] = $data[$key]; unset($data[$key]); } $data["ext"] = serialize($data["ext"]); Unserializing and unpacking this 'ext' column on read queries is a minor overhead. The advantage is that there won't be any sparsely filled columns in the database, so I guess it's compacter and faster than the AUTO ALTER TABLE approach. Of course, this method prevents ever using one of the new fields in a WHERE or GROUP BY clause. But I think none of the possible meta fields (user_agent, author_ip, author_img, votes, hits, last_modified, ..) would/should ever be used there anyway. So I currently prefer the 'ext' blob approach, even if it's a one-way ticket. How are such columns called usually? (looking for examples/doc) Would you use XML serialization for (very theoretical) in-database queries? The adapting table scheme seems a "cleaner" interface, even if most columns might remain empty then. How does that impact speed? How many such sparse VARCHAR fields can MySQL/innodb stomach? But most importantly: Is there any standard implementation for this? A pseudo ORM with automatic ALTER TABLE tricks? Storing a simple column list seems workable, but something like pdo::getColumnMeta would be more robust.

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• When I try to redefine a variable, I get an index out of bounds error

  - by user2770254

  I'm building a program to act as a calculator with memory, so you can give variables and their values. Whenever I'm trying to redefine a variable, a = 5, to a = 6, I get an index out of bounds error. public static void main(String args[]) { LinkedHashMap<String,Integer> map = new LinkedHashMap<String,Integer>(); Scanner scan = new Scanner(System.in); ArrayList<Integer> values = new ArrayList<>(); ArrayList<String> variables = new ArrayList<>(); while(scan.hasNextLine()) { String line = scan.nextLine(); String[] tokens = line.split(" "); if(!Character.isDigit(tokens[0].charAt(0)) && !line.equals("clear") && !line.equals("var")) { int value = 0; for(int i=0; i<tokens.length; i++) { if(tokens.length==3) { value = Integer.parseInt(tokens[2]); System.out.printf("%5d\n",value); if(map.containsKey(tokens[0])) { values.set(values.indexOf(tokens[0]), value); variables.set(variables.indexOf(tokens[0]), tokens[0]); } else { values.add(value); } break; } else if(tokens[i].charAt(0) == '+') { value = addition(tokens, value); System.out.printf("%5d\n",value); variables.add(tokens[0]); if(map.containsKey(tokens[0])) { values.set(values.indexOf(tokens[0]), value); variables.set(variables.indexOf(tokens[0]), tokens[0]); } else { values.add(value); } break; } else if(i==tokens.length-1 && tokens.length != 3) { System.out.println("No operation"); break; } } map.put(tokens[0], value); } if(Character.isDigit(tokens[0].charAt(0))) { int value = 0; if(tokens.length==1) { System.out.printf("%5s\n", tokens[0]); } else { value = addition(tokens, value); System.out.printf("%5d\n", value); } } if(line.equals("clear")) { clear(map); } if(line.equals("var")) { variableList(variables, values); } } } public static int addition(String[] a, int b) { for(String item : a) { if(Character.isDigit(item.charAt(0))) { int add = Integer.parseInt(item); b = b + add; } } return b; } public static void clear(LinkedHashMap<String,Integer> b) { b.clear(); } public static void variableList(ArrayList<String> a, ArrayList<Integer> b) { for(int i=0; i<a.size(); i++) { System.out.printf("%5s: %d\n", a.get(i), b.get(i)); } } I included the whole code because I'm not sure where the error is arising from.

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• How can I make the storage of C++ lambda objects more efficient?

  - by Peter Ruderman

  I've been thinking about storing C++ lambda's lately. The standard advice you see on the Internet is to store the lambda in a std::function object. However, none of this advice ever considers the storage implications. It occurred to me that there must be some seriously black voodoo going on behind the scenes to make this work. Consider the following class that stores an integer value: class Simple { public: Simple( int value ) { puts( "Constructing simple!" ); this->value = value; } Simple( const Simple& rhs ) { puts( "Copying simple!" ); this->value = rhs.value; } Simple( Simple&& rhs ) { puts( "Moving simple!" ); this->value = rhs.value; } ~Simple() { puts( "Destroying simple!" ); } int Get() const { return this->value; } private: int value; }; Now, consider this simple program: int main() { Simple test( 5 ); std::function<int ()> f = [test] () { return test.Get(); }; printf( "%d\n", f() ); } This is the output I would hope to see from this program: Constructing simple! Copying simple! Moving simple! Destroying simple! 5 Destroying simple! Destroying simple! First, we create the value test. We create a local copy on the stack for the temporary lambda object. We then move the temporary lambda object into memory allocated by std::function. We destroy the temporary lambda. We print our output. We destroy the std::function. And finally, we destroy the test object. Needless to say, this is not what I see. When I compile this on Visual C++ 2010 (release or debug mode), I get this output: Constructing simple! Copying simple! Copying simple! Copying simple! Copying simple! Destroying simple! Destroying simple! Destroying simple! 5 Destroying simple! Destroying simple! Holy crap that's inefficient! Not only did the compiler fail to use my move constructor, but it generated and destroyed two apparently superfluous copies of the lambda during the assignment. So, here finally are the questions: (1) Is all this copying really necessary? (2) Is there some way to coerce the compiler into generating better code? Thanks for reading!

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• Help in building an 16 bit os

  - by Barshan Das

  I am trying to build an old 16 bit dos like os. My bootloader code: ; This is not my code. May be of Fritzos. I forgot the source. ORG 7c00h jmp Start drive db 0 msg db " Loader Initialization",0 msg2 db "ACos Loaded",0 print: lodsb cmp al, 0 je end mov ah, 0Eh int 10h jmp print end: ret Start: mov [ drive ], dl ; Get the floppy OS booted from ; Update the segment registers xor ax, ax ; XOR ax mov ds, ax ; Mov AX into DS mov si,msg call print ; Load Kernel. ResetFloppy: mov ax, 0x00 ; Select Floppy Reset BIOS Function mov dl, [ drive ] ; Select the floppy ADos booted from int 13h ; Reset the floppy drive jc ResetFloppy ; If there was a error, try again. ReadFloppy: mov bx, 0x9000 ; Load kernel at 9000h. mov ah, 0x02 ; Load disk data to ES:BX mov al, 17 ; Load two floppy head full's worth of data. mov ch, 0 ; First Cylinder mov cl, 2 ; Start at the 2nd Sector to load the Kernel mov dh, 0 ; Use first floppy head mov dl, [ drive ] ; Load from the drive kernel booted from. int 13h ; Read the floppy disk. jc ReadFloppy ; Error, try again. ; Clear text mode screen mov ax, 3 int 10h ;print starting message mov si,msg2 call print mov ax, 0x0 mov ss, ax mov sp, 0xFFFF jmp 9000h ; This part makes sure the bootsector is 512 bytes. times 510-($-$$) db 0 ;bootable sector signature dw 0xAA55 My example kernel code: asm(".code16\n"); void putchar(char); int main() { putchar('A'); return 0; } void putchar(char val) { asm("movb %0, %%al\n" "movb $0x0E, %%ah\n" "int $0x10\n" : :"r"(val) ) ; } This is how I compile it : nasm -f bin -o ./bin/boot.bin ./source/boot.asm gcc -nostdinc -fno-builtin -I./include -c -o ./bin/kernel.o ./source/kernel.c ld -Ttext=0x9000 -o ./bin/kernel.bin ./bin/kernel.o -e 0x0 dd if=/dev/zero of=./bin/empty.bin bs=1440K count=1 cat ./bin/boot.bin ./bin/kernel.bin ./bin/empty.bin|head -c 1440K > ./bin/os rm ./bin/empty.bin and I run it in virtual machine. When I make the putchar function ( in kernel code ) for constant value ....i.e like this: void putchar() { char val = 'A'; asm("movb %0, %%al\n" "movb $0x0E, %%ah\n" "int $0x10\n" : :"r"(val) ) ; } then it works fine. But when I pass argument to it ( That is in the previous code ) , then it prints a space for any character. What should I do?

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• What is the best practice when coding math class/functions ?

  - by Isaac Clarke

  Introductory note : I voluntarily chose a wide subject. You know that quote about learning a cat to fish, that's it. I don't need an answer to my question, I need an explanation and advice. I know you guys are good at this ;) Hi guys, I'm currently implementing some algorithms into an existing program. Long story short, I created a new class, "Adder". An Adder is a member of another class representing the physical object actually doing the calculus , which calls adder.calc() with its parameters (merely a list of objects to do the maths on). To do these maths, I need some parameters, which do not exist outside of the class (but can be set, see below). They're neither config parameters nor members of other classes. These parameters are D1 and D2, distances, and three arrays of fixed size : alpha, beta, delta. I know some of you are more comfortable reading code than reading text so here you go : class Adder { public: Adder(); virtual Adder::~Adder(); void set( float d1, float d2 ); void set( float d1, float d2, int alpha[N_MAX], int beta[N_MAX], int delta[N_MAX] ); // Snipped prototypes float calc( List& ... ); // ... inline float get_d1() { return d1_ ;}; inline float get_d2() { return d2_ ;}; private: float d1_; float d2_; int alpha_[N_MAX]; // A #define N_MAX is done elsewhere int beta_[N_MAX]; int delta_[N_MAX]; }; Since this object is used as a member of another class, it is declared in a *.h : private: Adder adder_; By doing that, I couldn't initialize the arrays (alpha/beta/delta) directly in the constructor ( int T[3] = { 1, 2, 3 }; ), without having to iterate throughout the three arrays. I thought of putting them in static const, but I don't think that's the proper way of solving such problems. My second guess was to use the constructor to initialize the arrays Adder::Adder() { int alpha[N_MAX] = { 0, -60, -120, 180, 120, 60 }; int beta[N_MAX] = { 0, 0, 0, 0, 0, 0 }; int delta[N_MAX] = { 0, 0, 180, 180, 180, 0 }; set( 2.5, 0, alpha, beta, delta ); } void Adder::set( float d1, float d2 ) { if (d1 > 0) d1_ = d1; if (d2 > 0) d2_ = d2; } void Adder::set( float d1, float d2, int alpha[N_MAX], int beta[N_MAX], int delta[N_MAX] ) { set( d1, d2 ); for (int i = 0; i < N_MAX; ++i) { alpha_[i] = alpha[i]; beta_[i] = beta[i]; delta_[i] = delta[i]; } } My question is : Would it be better to use another function - init() - which would initialize arrays ? Or is there a better way of doing that ? My bonus question is : Did you see some mistakes or bad practice along the way ?

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• can a python script know that another instance of the same script is running... and then talk to it?

  - by Justin Grant

  I'd like to prevent multiple instances of the same long-running python command-line script from running at the same time, and I'd like the new instance to be able to send data to the original insance before the new instance commits suicide. How can I do this in a cross-platform way? Specifically, I'd like to enable the following behavior: "foo.py" is launched from the command line, and it will stay running for a long time-- days or weeks until the machine is rebooted or the parent process kills it. every few minutes the same script is launched again, but with different command-line parameters when launched, the script should see if any other instances are running. if other instances are running, then instance #2 should send its command-line parameters to instance #1, and then instance #2 should exit. instance #1, if it receives command-line parameters from another script, should spin up a new thread and (using the command-line parameters sent in the step above) start performing the work that instance #2 was going to perform. So I'm looking for two things: how can a python program know another instance of itself is running, and then how can one python command-line program communicate with another? Making this more complicated, the same script needs to run on both Windows and Linux, so ideally the solution would use only the Python standard library and not any OS-specific calls. Although if I need to have a Windows codepath and an *nix codepath (and a big if statement in my code to choose one or the other), that's OK if a "same code" solution isn't possible. I realize I could probably work out a file-based approach (e.g. instance #1 watches a directory for changes and each instance drops a file into that directory when it wants to do work) but I'm a little concerned about cleaning up those files after a non-graceful machine shutdown. I'd ideally be able to use an in-memory solution. But again I'm flexible, if a persistent-file-based approach is the only way to do it, I'm open to that option. More details: I'm trying to do this because our servers are using a monitoring tool which supports running python scripts to collect monitoring data (e.g. results of a database query or web service call) which the monitoring tool then indexes for later use. Some of these scripts are very expensive to start up but cheap to run after startup (e.g. making a DB connection vs. running a query). So we've chosen to keep them running in an infinite loop until the parent process kills them. This works great, but on larger servers 100 instances of the same script may be running, even if they're only gathering data every 20 minutes each. This wreaks havoc with RAM, DB connection limits, etc. We want to switch from 100 processes with 1 thread to one process with 100 threads, each executing the work that, previously, one script was doing. But changing how the scripts are invoked by the monitoring tool is not possible. We need to keep invocation the same (launch a process with different command-line parameters) but but change the scripts to recognize that another one is active, and have the "new" script send its work instructions (from the command line params) over to the "old" script.

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• Want to Receive dynamic length data from a message queue in IPC?

  - by user1089679

  Here I have to send and receive dynamic data using a SysV message queue. so in structure filed i have dynamic memory allocation char * because its size may be varies. so how can i receive this type of message at receiver side. Please let me know how can i send dynamic length of data with message queue. I am getting problem in this i posted my code below. send.c /*filename : send.c *To compile : gcc send.c -o send */ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <string.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> struct my_msgbuf { long mtype; char *mtext; }; int main(void) { struct my_msgbuf buf; int msqid; key_t key; static int count = 0; char temp[5]; int run = 1; if ((key = ftok("send.c", 'B')) == -1) { perror("ftok"); exit(1); } printf("send.c Key is = %d\n",key); if ((msqid = msgget(key, 0644 | IPC_CREAT)) == -1) { perror("msgget"); exit(1); } printf("Enter lines of text, ^D to quit:\n"); buf.mtype = 1; /* we don't really care in this case */ int ret = -1; while(run) { count++; buf.mtext = malloc(50); strcpy(buf.mtext,"Hi hello test message here"); snprintf(temp, sizeof (temp), "%d",count); strcat(buf.mtext,temp); int len = strlen(buf.mtext); /* ditch newline at end, if it exists */ if (buf.mtext[len-1] == '\n') buf.mtext[len-1] = '\0'; if (msgsnd(msqid, &buf, len+1, IPC_NOWAIT) == -1) /* +1 for '\0' */ perror("msgsnd"); if(count == 100) run = 0; usleep(1000000); } if (msgctl(msqid, IPC_RMID, NULL) == -1) { perror("msgctl"); exit(1); } return 0; } receive.c /* filename : receive.c * To compile : gcc receive.c -o receive */ #include <stdio.h> #include <stdlib.h> #include <errno.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> struct my_msgbuf { long mtype; char *mtext; }; int main(void) { struct my_msgbuf buf; int msqid; key_t key; if ((key = ftok("send.c", 'B')) == -1) { /* same key as send.c */ perror("ftok"); exit(1); } if ((msqid = msgget(key, 0644)) == -1) { /* connect to the queue */ perror("msgget"); exit(1); } printf("test: ready to receive messages, captain.\n"); for(;;) { /* receive never quits! */ buf.mtext = malloc(50); if (msgrcv(msqid, &buf, 50, 0, 0) == -1) { perror("msgrcv"); exit(1); } printf("test: \"%s\"\n", buf.mtext); } return 0; }

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• Mbean registered but not found in mbean Server

  - by Prisco

  I have a problem about the mbeans. I have created a simple mbean and I have registered it on the default mBeanServer that is run (Via eclipse or java -jar mbean.jar) and in the same process if I try to fouund the mbean registered with a simple query: for (ObjectInstance instance : mbs.queryMBeans(ObjectNameMbean, null)) { System.out.println(instance.toString()); } the query retuerns my mbean, but if I start another process and try to search this mbean registered the mbeas is not found! why? The approch is : (Process that is running) public static void main(String[] args) throws Exception { MBeanServer mbeanServer =ManagementFactory.getPlatformMBeanServer(); ObjectName objectName = new ObjectName(ObjectNameMbean); Simple simple = new Simple (1, 0); mbeanServer.registerMBean(simple, objectName); while (true) { wait (Is this necessary?) } } So this is the first process that is running (that has the only pourpose to registry the mbean, because there is another process that want to read these informations. So I start another process to search this mbean but nothing. I 'm not using jboss but the local Java virtual Machine but my scope is to deploy this simple application in one ejb (autostart) and another ejb will read all informations. All suggestions are really apprecciated. This example should be more useful : Object Hello: public class Hello implements HelloMBean { public void sayHello() { System.out.println("hello, world"); } public int add(int x, int y) { return x + y; } public String getName() { return this.name; } public int getCacheSize() { return this.cacheSize; } public synchronized void setCacheSize(int size) { this.cacheSize = size; System.out.println("Cache size now " + this.cacheSize); } private final String name = "Reginald"; private int cacheSize = DEFAULT_CACHE_SIZE; private static final int DEFAULT_CACHE_SIZE = 200; } Interface HelloBean (implemented by Hello) public interface HelloMBean { public void sayHello(); public int add(int x, int y); public String getName(); public int getCacheSize(); public void setCacheSize(int size); } Simple Main import java.lang.management.ManagementFactory; import java.util.logging.Logger; import javax.management.MBeanServer; import javax.management.ObjectName; public class Main { static Logger aLog = Logger.getLogger("MBeanTest"); public static void main(String[] args) { try{ MBeanServer mbs = ManagementFactory.getPlatformMBeanServer(); ObjectName name = new ObjectName("ApplicationDomain:type=Hello"); Hello mbean = new Hello(); mbs.registerMBean(mbean, name); // System.out.println(mbs.getAttribute(name, "Name")); aLog.info("Waiting forever..."); Thread.sleep(Long.MAX_VALUE); } catch(Exception x){ x.printStackTrace(); aLog.info("exception"); } } } So now I have exported this project as jar file and run it as "java -jar helloBean.jar" and by eclipse I have modified the main class to read informations of this read (Example "Name" attribute) by using the same objectname used to registry it . Main to read : public static void main(String[] args) { try{ MBeanServer mbs = ManagementFactory.getPlatformMBeanServer(); ObjectName name = new ObjectName("ApplicationDomain:type=Hello"); System.out.println(mbs.getAttribute(name, "Name")); } catch(Exception x){ x.printStackTrace(); aLog.info("exception"); } } But nothing, the bean is not found.

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• OpenGL texture misaligned on quad

  - by user308226

  I've been having trouble with this for a while now, and I haven't gotten any solutions that work yet. Here is the problem, and the specifics: I am loading a 256x256 uncompressed TGA into a simple OpenGL program that draws a quad on the screen, but when it shows up, it is shifted about two pixels to the left, with the cropped part appearing on the right side. It has been baffling me for the longest time, people have suggested clamping and such, but somehow I think my problem is probably something really simple, but I just can't figure out what it is! Here is a screenshot comparing the TGA (left) and how it appears running in the program (right) for clarity. Also take note that there's a tiny black pixel on the upper right corner, I'm hoping that's related to the same problem. Here's the code for the loader, I'm convinced that my problem lies in the way that I'm loading the texture. Thanks in advance to anyone who can fix my problem. bool TGA::LoadUncompressedTGA(char *filename,ifstream &texturestream) { cout << "G position status:" << texturestream.tellg() << endl; texturestream.read((char*)header, sizeof(header)); //read 6 bytes into the file to get the tga header width = (GLuint)header[1] * 256 + (GLuint)header[0]; //read and calculate width and save height = (GLuint)header[3] * 256 + (GLuint)header[2]; //read and calculate height and save bpp = (GLuint)header[4]; //read bpp and save cout << bpp << endl; if((width <= 0) || (height <= 0) || ((bpp != 24) && (bpp !=32))) //check to make sure the height, width, and bpp are valid { return false; } if(bpp == 24) { type = GL_RGB; } else { type = GL_RGBA; } imagesize = ((bpp/8) * width * height); //determine size in bytes of the image cout << imagesize << endl; imagedata = new GLubyte[imagesize]; //allocate memory for our imagedata variable texturestream.read((char*)imagedata,imagesize); //read according the the size of the image and save into imagedata for(GLuint cswap = 0; cswap < (GLuint)imagesize; cswap += (bpp/8)) //loop through and reverse the tga's BGR format to RGB { imagedata[cswap] ^= imagedata[cswap+2] ^= //1st Byte XOR 3rd Byte XOR 1st Byte XOR 3rd Byte imagedata[cswap] ^= imagedata[cswap+2]; } texturestream.close(); //close ifstream because we're done with it cout << "image loaded" << endl; glGenTextures(1, &texID); // Generate OpenGL texture IDs glBindTexture(GL_TEXTURE_2D, texID); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); glTexImage2D(GL_TEXTURE_2D, 0, type, width, height, 0, type, GL_UNSIGNED_BYTE, imagedata); delete imagedata; return true; } //Public loading function for TGA images. Opens TGA file and determines //its type, if any, then loads it and calls the appropriate function. //Returns: TRUE on success, FALSE on failure bool TGA::loadTGA(char *filename) { cout << width << endl; ifstream texturestream; texturestream.open(filename,ios::binary); texturestream.read((char*)header,sizeof(header)); //read 6 bytes into the file, its the header. //if it matches the uncompressed header's first 6 bytes, load it as uncompressed LoadUncompressedTGA(filename,texturestream); return true; }

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• Windows Mobile 6.5 GPS Device - WaitForMultipleObjects returns 258 (timeout)

  - by wizmagister

  I’ve created a GPS program that track positions in realtime in the background for Windows mobile 6.1 in 2008-2009. It ran fine on these devices for many years. For some reason, the same code never worked perfectly on Windows Mobile 6.5. After many hour of operations (mostly when nobody use the device), I receive a “Timeout” (code 258) from the function "WaitForMultipleObjects": this.GPSEvent_WaitValue = WaitForMultipleObjects(2, this.GPSEvent_Handles, 0, 45000); Again, this can work for hours and suddenly, it's just impossible to get another position without : UPDATE: - Restarting the device (GoogleMap confirms that there's no GPS device present!) It has something to do with Windows Mobile going to sleep and slowing up my thread. Here's the core code (adapted from Microsoft SDK Sample): /// <summary> /// When "WindowsMobile" wake up the program to check for a new position /// </summary> private void OnNextGPSEvent_Callback() { int SecondsToNextWakeUp = ETL.Mobile.Device.ScheduledCallback.MINIMUM_SECONDTONEXTWAKEUP; switch (this.SleepingState) { case SleepingStateType.SleepingForNextPosition: // Get position this.GPSEvent_WaitValue = (WaitForEventThreadResultType)WaitForMultipleObjects(2, this.GPSEvent_Handles, 0, 45000); switch (this.GPSEvent_WaitValue) { case WaitForEventThreadResultType.Event_LocationChanged: // Got a new position this.FireLocationChanged(this.GetCurrentPosition()); // Manage device shutdown (save battery) if (this.PositionFrequency > MIN_SECONDS_FREQUENCY_FORDEVICE_SHUTDOWN) { // Close device this.CloseDevice(); SecondsToNextWakeUp = (this.PositionFrequency - GPSDEVICE_LOAD_SECONDS_LOAD_TIME); this.SleepingState = SleepingStateType.SleepingBeforeDeviceWakeUp; } else { // Default Wait Time this.SleepingState = SleepingStateType.SleepingForNextPosition; } break; case WaitForEventThreadResultType.Event_StateChanged: break; case WaitForEventThreadResultType.Timeout: case WaitForEventThreadResultType.Failed: case WaitForEventThreadResultType.Stop: // >>>>>>>>>>>>>> This is where the error happens <<<<<<<<<<<<<<<<<<<<<<<<<<< // >>>>>>>>>>>>>> This is where the error happens <<<<<<<<<<<<<<<<<<<<<<<<<<< // >>>>>>>>>>>>>> This is where the error happens <<<<<<<<<<<<<<<<<<<<<<<<<<< // Too many errors this.ConsecutiveErrorReadingDevice++; if (this.ConsecutiveErrorReadingDevice > MAX_ERRORREADINGDEVICE) { this.CloseDevice(); SecondsToNextWakeUp = (this.PositionFrequency - GPSDEVICE_LOAD_SECONDS_LOAD_TIME); this.SleepingState = SleepingStateType.SleepingBeforeDeviceWakeUp; } else { // Default Wait Time this.SleepingState = SleepingStateType.SleepingForNextPosition; } break; } #endregion break; case SleepingStateType.SleepingBeforeDeviceWakeUp: this.OpenDevice(); SecondsToNextWakeUp = GPSDEVICE_LOAD_SECONDS_LOAD_TIME; this.SleepingState = SleepingStateType.SleepingForNextPosition; break; } if (this.IsListeningGPSEvent) { // Ajustement du prochain rappel this.NextGPSEvent_Callback.SecondToNextWakeUp = SecondsToNextWakeUp; this.NextGPSEvent_Callback.RequestWakeUpCallback(); } } /// <summary> ///Create Thread /// </summary> private void StartListeningThreadForGPSEvent() { // We only want to create the thread if we don't have one created already and we have opened the gps device if (this._GPSEventThread == null) { // Create and start thread to listen for GPS events this._GPSEventThread = new System.Threading.Thread(new System.Threading.ThreadStart(this.ListeningThreadForGPSEvent)); this._GPSEventThread.Start(); } } private void ListeningThreadForGPSEvent() { this.GPSEvent_WaitValue = WaitForEventThreadResultType.Stop; this.IsListeningGPSEvent = true; // Allocate handles worth of memory to pass to WaitForMultipleObjects this.GPSEvent_Handles = Helpers.LocalAlloc(12); Marshal.WriteInt32(this.GPSEvent_Handles, 0, this._StopHandle.ToInt32()); Marshal.WriteInt32(this.GPSEvent_Handles, 4, this._NewLocationHandle.ToInt32()); Marshal.WriteInt32(this.GPSEvent_Handles, 8, this._GPSDeviceStateChanged.ToInt32()); this.Start_NextGPSEvent_Timer(this.PositionFrequency); this.SleepingState = SleepingStateType.SleepingBeforeDeviceWakeUp; this.OnNextGPSEvent_Callback(); }

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• win32: TextOut not being displayed

  - by KaiserJohaan

  Hello again, I recently having my mainwindow write text by using WM_PAINT, but now I realise it was maybe not the best message to do so in, so I'm trying another version; The mainwindow contains a menu, upon clicing a menu item the ID_FILE_PID msg is sent and it builds the 4 new windows aswell as displays text in the mainwindow (paintEditSigns function). The 4 windows works fine but the text dosn't work at all, unless I do it in the main() function as shown... what on earth is this? O_O BTW: I still have no clue why the code-display on StackOverflow keeps looking so wierd when I post, why is this? switch(message) { case WM_COMMAND: switch (LOWORD(wParam)) { case ID_FILE_PID: { HWND hWndButton; HWND hWndEdit; HWND hWndEdit2; HWND hWndDisplay; // drawing the text in mainwindow paintEditSigns(); -- does not do anything here! // adding new windows in the mainwindow hWndButton = CreateWindowEx(0,TEXT("BUTTON"),"Modify",WS_CHILD | WS_VISIBLE | BS_DEFPUSHBUTTON, 170,56,80,30,hWnd,(HMENU)ID_BUTTON,hThisInstance,NULL); hWndEdit = CreateWindowEx(0,RICHEDIT_CLASS,TEXT(""),WS_CHILD | WS_VISIBLE | WS_BORDER, 120,30,80,25,hWnd,(HMENU)ID_EDIT,hThisInstance,NULL); hWndEdit2 = CreateWindowEx(0,RICHEDIT_CLASS,TEXT(""),WS_CHILD | WS_VISIBLE | WS_BORDER, 220,30,80,25,hWnd,(HMENU)ID_EDIT2,hThisInstance,NULL); hWndDisplay = CreateWindowEx(0,TEXT("STATIC"),NULL,WS_CHILD | WS_VISIBLE | WS_BORDER, 0,100,450,140,hWnd,(HMENU)ID_DISPLAY,hThisInstance,NULL); break; } ..... // // Main function // int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { HWND hWnd; WNDCLASSEX wc; ZeroMemory(&wc, sizeof(WNDCLASSEX)); hThisInstance = hInstance; LoadLibrary("Riched20.dll"); wc.cbSize = sizeof(WNDCLASSEX); wc.style = CS_HREDRAW | CS_VREDRAW; wc.lpfnWndProc = WindowProc; wc.hInstance = hInstance; wc.lpszMenuName = MAKEINTRESOURCE(IDR_MYMENU); if(!(wc.hIcon = LoadIcon(hInstance,MAKEINTRESOURCE(IDI_MYICON)))) { HRESULT res = GetLastError(); } wc.hCursor = LoadCursor(NULL, IDC_ARROW); wc.hbrBackground = (HBRUSH)COLOR_WINDOW; wc.lpszClassName = TEXT("testcpp"); RegisterClassEx(&wc); hWnd = CreateWindowEx(NULL, wc.lpszClassName, TEXT("test"), WS_OVERLAPPEDWINDOW, 300, 200, 450, 300, NULL, NULL, hInstance, NULL); ShowWindow(hWnd,nCmdShow); //paintEditSigns() -- here it works, but not when in the message part MSG msg; while (GetMessage(&msg, NULL,0,0)) { TranslateMessage(&msg); DispatchMessage(&msg); } return msg.wParam; } void paintEditSigns() { HFONT hf = createFont(); PAINTSTRUCT ps; HWND hWnd = FindWindow(TEXT("testcpp"),TEXT("test")); HBRUSH hbruzh = CreateSolidBrush(RGB(0,0,0)); HDC hdz = BeginPaint(hWnd,&ps); string s = "Memory Address"; SelectBrush(hdz,hbruzh); SelectFont(hdz,hf); TextOut(hdz,0,100,s.c_str(),s.length()); EndPaint(hWnd,&ps); DeleteObject(hbruzh); UpdateWindow(hWnd); } HFONT createFont() { HDC hdc; long lfHeight; hdc = GetDC(NULL); lfHeight = -MulDiv(12, GetDeviceCaps(hdc, LOGPIXELSY), 72); ReleaseDC(NULL, hdc); HFONT hf = CreateFont(lfHeight, 0, 0, 0, 0, TRUE, 0, 0, 0, 0, 0, 0, 0, "MS Sans Serif"); return hf; }

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• Faulty to use memcache together with a php web-browser-game in this way?

  - by Crowye

  Background We are currently working on a strategy web-browser game based on php, html and javascript. The plan is to have 10,000+ users playing within the same world. Currently we are using memcached to: store json static data, language files store changeable serialized php class objects (such as armies, inventorys, unit-containers, buildings, etc) In the back we have a mysql server running and holding all the game data aswell. When a object is loaded through our ObjectLoader it loads in this order: checks a static hashmap in the script for the object checks memcache if it has already been loaded into it otherwise loads from database, and saves it into memcache and the static temp hashmap We have built the whole game using a class-object-oriented approach where functionality is always made between objects. Beause of this we think we have managed to get a nice structure, and with the help of memcached we have received good request times from client-server when interacting with the game. I'm aware that memcache is not synchronized, and also is not commonly used for holding a full game in memory. In the beginning after a server's startup the load times when loading objects into memcache for the first time will be high, but after the server's been online for a while and most loads are from memcache, the loads will be well reduced. Currently we are saving changed objects into memcache and database at the same time. Earlier we had an idea to save objects into db only after a certain time or at intervals, but due to risk inconsistency if the memcache/server went down, we skipped it for now. Client requests to server often return object's status simple json-format without changing the object, which in turn is represented in the browser visually with images and javascript. But from time to time depending on when an object was last updated, it updates them with new information (e.g. a build-queue holding planned buildings time-progress is increased, and/or planned-queue-items-array has changed). Questions: Do you see how this could work or are we walking in blindness here? Do you expect us to have a lot of inconsistency issues if someone loads and updates the a memcache objects while someone else does the same? Is it even doable to do it in the way he have done it? Seems to be working fine atm, but so far we have only been 4 people online at the same time.. Is some other cache program more fit for this class-object approach than memcached? Is there any other tips you have for this situation? UPDATE Since it is simply a "normal webpage" (no applet, flash, etc), we are implementing the game so that the server is the only one holding a "real game-state".. the state of the different javascript-objects on the client is more like a approximative version of the server's game state. From time to time and before you do certain things important things, the client's visual state is updated to the server's state (e.g. the client things he can afford a barracks, asks the server to build a barracks, server updates current resources according to income-data on server and then tries to build a barracks or casts an error-message, and then sends the current server-state on resources, buildings back to the client).. It is not a fast-paced game lika real strategy game. More like a quite slow 3-4 months playtime game, where buildings can take +1 minute up to several days to complete.

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• .NET GDI+ image size - file codec limitations

  - by roygbiv

  Is there a limit on the size of image that can be encoded using the image file codecs available from .NET? I'm trying to encode images 4GB in size, but it simply does not work (or does not work properly i.e. writes out an unreadable file) with .bmp, .jpg, .png or the .tif encoders. When I lower the image size to < 2GB it does work with the .jpg but not the .bmp, .tif or .png. My next attempt would be to try libtiff because I know tiff files are meant for large images. What is a good file format for large images? or am I just hitting the file format limitations? Random r = new Random((int)DateTime.Now.Ticks); int width = 64000; int height = 64000; int stride = (width % 4) > 0 ? width + (width % 4) : width; UIntPtr dataSize = new UIntPtr((ulong)stride * (ulong)height); IntPtr p = Program.VirtualAlloc(IntPtr.Zero, dataSize, Program.AllocationType.COMMIT | Program.AllocationType.RESERVE, Program.MemoryProtection.READWRITE); Bitmap bmp = new Bitmap(width, height, stride, PixelFormat.Format8bppIndexed, p); BitmapData bd = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height), ImageLockMode.ReadWrite, bmp.PixelFormat); ColorPalette cp = bmp.Palette; for (int i = 0; i < cp.Entries.Length; i++) { cp.Entries[i] = Color.FromArgb(i, i, i); } bmp.Palette = cp; unsafe { for (int y = 0; y < bd.Height; y++) { byte* row = (byte*)bd.Scan0.ToPointer() + (y * bd.Stride); for (int x = 0; x < bd.Width; x++) { *(row + x) = (byte)r.Next(256); } } } bmp.UnlockBits(bd); bmp.Save(@"c:\test.jpg", ImageFormat.Jpeg); bmp.Dispose(); Program.VirtualFree(p, UIntPtr.Zero, 0x8000); I have also tried using a pinned GC memory region, but this is limited to < 2GB. Random r = new Random((int)DateTime.Now.Ticks); int bytesPerPixel = 4; int width = 4000; int height = 4000; int padding = 4 - ((width * bytesPerPixel) % 4); padding = (padding == 4 ? 0 : padding); int stride = (width * bytesPerPixel) + padding; UInt32[] pixels = new UInt32[width * height]; GCHandle gchPixels = GCHandle.Alloc(pixels, GCHandleType.Pinned); using (Bitmap bmp = new Bitmap(width, height, stride, PixelFormat.Format32bppPArgb, gchPixels.AddrOfPinnedObject())) { for (int y = 0; y < height; y++) { int row = (y * width); for (int x = 0; x < width; x++) { pixels[row + x] = (uint)r.Next(); } } bmp.Save(@"c:\test.jpg", ImageFormat.Jpeg); } gchPixels.Free();

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• ValidationProperty not returning entered value for textbox

  - by nat

  hi I have a custom control, (relevant code at the bottom) it consists of some text/links and a hidden textbox (rather than a hidden input). when rendered, the user via another dialog and some JS sets the value of the textbox to an integer and clicks submit on the form. i am trying to assure that the user has entered a number (via the JS) and that the textbox is not still set to its default of "0" the requiredfieldvalidator works just fine, if i dont change the value it spots it on the client and fills the validation summary on the page with the appropriate message. unfortunately when i do fill the textbox, the validator also rejests the post as the controls textbox text value is still set to "0", even though on the form it has changed. clearly i am doing something wrong.. but cant work out what it is? could someone enlighten me please, this is driving me potty if i step through the code, when the get of the mediaidtext is hit,the findcontrol finds the textbox, but the value is still set to "0" many thanks code below nat [ValidationProperty("MediaIdText")] public class MediaLibraryFileControl: CompositeControl { private int mediaId = 0; public int MediaId { get { return mediaId; } set { mediaId = value; } } public string MediaIdText { get { string txt = "0"; Control ctrl = this.FindControl(this.UniqueID+ "_hidden"); try { txt = ((TextBox)ctrl).Text; MediaId = Convert.ToInt32(txt); } catch { MediaId = 0; } return txt; } } protected override void CreateChildControls() { this.Controls.Add(new LiteralControl("<span>")); this.Controls.Add(new LiteralControl("<span id=\"" + TextControlName + "\">" + getMediaDetails() + "</span>")); TextBox tb = new TextBox(); tb.Text = this.MediaId.ToString(); tb.ID = this.UniqueID + "_hidden"; tb.CssClass = "hidden"; this.Controls.Add(tb); if (Select == true) { this.Controls.Add(new LiteralControl(string.Format("&nbsp;[<a href=\"javascript:{0}(this,'{1}','{2}')\" class=\"select\">{3}</a>]", dialog, this.UniqueID, this.categoryId, "select"))); this.Controls.Add(new LiteralControl(string.Format("&nbsp;[<a href=\"javascript:{0}(this,'{1}')\" class=\"select\">{2}</a>]", clearDialog, this.ID, "clear"))); } this.Controls.Add(new LiteralControl("</span>")); } protected virtual string getMediaDetails() { //... return String.Empty; } } this is the code adding the validationcontrol the editcontrol is the instance of the control above public override Control RenderValidationControl(Control editControl) { Control ctrl = new PlaceHolder(); RequiredFieldValidator req = new RequiredFieldValidator(); req.ID = editControl.ClientID + "_validator"; req.ControlToValidate = editControl.ID; req.Display = ValidatorDisplay.None; req.InitialValue = "0"; req.EnableClientScript = false; req.ErrorMessage = "control cannot be blank"; ctrl.Controls.Add(req); return ctrl; }

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• WCF/REST Get image into picturebox?

  - by Garrith

  So I have wcf rest service which succesfuly runs from a console app, if I navigate to: http://localhost:8000/Service/picture/300/400 my image is displayed note the 300/400 sets the width and height of the image within the body of the html page. The code looks like this: namespace WcfServiceLibrary1 { [ServiceContract] public interface IReceiveData { [OperationContract] [WebInvoke(Method = "GET", BodyStyle = WebMessageBodyStyle.Wrapped, ResponseFormat = WebMessageFormat.Xml, UriTemplate = "picture/{width}/{height}")] Stream GetImage(string width, string height); } public class RawDataService : IReceiveData { public Stream GetImage(string width, string height) { int w, h; if (!Int32.TryParse(width, out w)) { w = 640; } // Handle error if (!Int32.TryParse(height, out h)) { h = 400; } Bitmap bitmap = new Bitmap(w, h); for (int i = 0; i < bitmap.Width; i++) { for (int j = 0; j < bitmap.Height; j++) { bitmap.SetPixel(i, j, (Math.Abs(i - j) < 2) ? Color.Blue : Color.Yellow); } } MemoryStream ms = new MemoryStream(); bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); ms.Position = 0; WebOperationContext.Current.OutgoingResponse.ContentType = "image/jpeg"; return ms; } } } What I want to do now is use a client application "my windows form app" and add that image into a picturebox. Im abit stuck as to how this can be achieved as I would like the width and height of the image from my wcf rest service to be set by the width and height of the picturebox. I have tryed this but on two of the lines have errors and im not even sure if it will work as the code for my wcf rest service seperates width and height with a "/" if you notice in the url. string uri = "http://localhost:8080/Service/picture"; private void button1_Click(object sender, EventArgs e) { StringBuilder sb = new StringBuilder(); sb.AppendLine("<picture>"); sb.AppendLine("<width>" + pictureBox1.Image.Width + "</width>"); // the url looks like this http://localhost:8080/Service/picture/300/400 when accessing the image so I am trying to set this here sb.AppendLine("<height>" + pictureBox1.Image.Height + "</height>"); sb.AppendLine("</picture>"); string picture = sb.ToString(); byte[] getimage = Encoding.UTF8.GetBytes(picture); // not sure this is right HttpWebRequest req = WebRequest.Create(uri); //cant convert webrequest to httpwebrequest req.Method = "GET"; req.ContentType = "image/jpg"; req.ContentLength = getimage.Length; MemoryStream reqStrm = req.GetRequestStream(); //cant convert IO stream to IO Memory stream reqStrm.Write(getimage, 0, getimage.Length); reqStrm.Close(); HttpWebResponse resp = req.GetResponse(); // cant convert web respone to httpwebresponse MessageBox.Show(resp.StatusDescription); pictureBox1.Image = Image.FromStream(reqStrm); reqStrm.Close(); resp.Close(); } So just wondering if some one could help me out with this futile attempt at adding a variable image size from my rest service to a picture box on button click. This is the host app aswell: namespace ConsoleApplication1 { class Program { static void Main(string[] args) { string baseAddress = "http://" + Environment.MachineName + ":8000/Service"; ServiceHost host = new ServiceHost(typeof(RawDataService), new Uri(baseAddress)); host.AddServiceEndpoint(typeof(IReceiveData), new WebHttpBinding(), "").Behaviors.Add(new WebHttpBehavior()); host.Open(); Console.WriteLine("Host opened"); Console.ReadLine();

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• Android - Resuming application state - SL4A

  - by toyotajon93

  please dont harpoon me for a noob-ish question. I am working on an android application using SL4A, when my application starts it runs in the background while the script is being executed. I'm not sure where to start but each time I click my icon, it re-starts my application. I have tried using different launchmodes with nothing different happening. I'm thinking it has to do with the OnCreate code, and the setting of the notification. I need help saving my application state and then resuming on either re-click of icon or click from notification bar. I've tried everything had to turn here for help. I am not a pro at android programming by any means. Thanks guys, be gentle ;) Public void onCreate() { super.onCreate(); mInterpreterConfiguration = ((BaseApplication) getApplication()) .getInterpreterConfiguration(); } @Override public void onStart(Intent intent, final int startId) { super.onStart(intent, startId); String fileName = Script.getFileName(this); Interpreter interpreter = mInterpreterConfiguration .getInterpreterForScript(fileName); if (interpreter == null || !interpreter.isInstalled()) { mLatch.countDown(); if (FeaturedInterpreters.isSupported(fileName)) { Intent i = new Intent(this, DialogActivity.class); i.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); i.putExtra(Constants.EXTRA_SCRIPT_PATH, fileName); startActivity(i); } else { Log .e(this, "Cannot find an interpreter for script " + fileName); } stopSelf(startId); return; } // Copies script to internal memory. fileName = InterpreterUtils.getInterpreterRoot(this).getAbsolutePath() + "/" + fileName; File script = new File(fileName); // TODO(raaar): Check size here! if (!script.exists()) { script = FileUtils.copyFromStream(fileName, getResources() .openRawResource(Script.ID)); } copyResourcesToLocal(); // Copy all resources if (Script.getFileExtension(this) .equals(HtmlInterpreter.HTML_EXTENSION)) { HtmlActivityTask htmlTask = ScriptLauncher.launchHtmlScript(script, this, intent, mInterpreterConfiguration); mFacadeManager = htmlTask.getRpcReceiverManager(); mLatch.countDown(); stopSelf(startId); } else { mProxy = new AndroidProxy(this, null, true); mProxy.startLocal(); mLatch.countDown(); ScriptLauncher.launchScript(script, mInterpreterConfiguration, mProxy, new Runnable() { @Override public void run() { mProxy.shutdown(); stopSelf(startId); } }); } } RpcReceiverManager getRpcReceiverManager() throws InterruptedException { mLatch.await(); if (mFacadeManager==null) { // Facade manage may not be available on startup. mFacadeManager = mProxy.getRpcReceiverManagerFactory() .getRpcReceiverManagers().get(0); } return mFacadeManager; } @Override protected Notification createNotification() { Notification notification = new Notification(R.drawable.script_logo_48, this.getString(R.string.loading), System.currentTimeMillis()); // This contentIntent is a noop. PendingIntent contentIntent = PendingIntent.getService(this, 0, new Intent(), 0); notification.setLatestEventInfo(this, this.getString(R.string.app_name), this.getString(R.string.loading), contentIntent); notification.flags = Notification.FLAG_ONGOING_EVENT; return notification; }

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