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  • Time taken for memcpy decreases after certain point

    - by tss
    I ve a code which increases the size of the memory(identified by a pointer) exponentially. Instead of realloc, I use malloc followed by memcpy.. Something like this.. int size=5,newsize; int *c = malloc(size*sizeof(int)); int *temp; while(1) { newsize=2*size; //begin time temp=malloc(newsize*sizeof(int)); memcpy(temp,c,size*sizeof(int)); //end time //print time in mili seconds c=temp; size=newsize; } Thus the number of bytes getting copied is increasing exponentially. The time required for this task also increases almost linearly with the increase in size. However after certain point, the time taken abruptly reduces to a very small value and then remains constant. I recorded time for similar code, copyin data(Of my own type) 5 -> 10 - 2 ms 10 -> 20 - 2 ms . . 2560 -> 5120 - 5 ms . . 20480 -> 40960 - 30 ms 40960 -> 91920 - 58 ms 367680 -> 735360 - 2 ms 735360 -> 1470720 - 2 ms 1470720 -> 2941440 - 2 ms What is the reason for this drop in time ? Does a more optimal memcpy method get called when the size is large ?

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  • Which way to store this data is effective?

    - by Tattat
    I am writing a game, which need a map, and I want to store the map. The first thing I can think of, is using a 2D-array. But the problem is what data should I store in the 2D-array. The player can tap different place to have different reaction. So, I am thinking store a 2D-array with objects, when player click some position, and I find it in the array, and use the object in that array to execute a cmd. But I have a concern that storing lots of object may use lots of memory. So, I am think storing char/int only. But it seems that not enough for me. I want to store the data like that: { Type:1 Color:Green } No matter what color is, if they are all type 1, the have same reactions in logic, but the visual effect is based on the color. So, it is not easy to store using a prue char/int data, unless I make something like this: 1-5 --> all type 1. 1=color green , 2=color red, 3 = color yellow.... ... 6-10 --> all type 2. 2 = color green, 2 = color red ... ... So, do you have any ideas on how to minimize the ram use, but also easy for me to read... ...thx

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  • transferring binary files between systems

    - by tim
    Hi guys I'm trying to transfer my files between 2 UNIX clusters, the data is pure numeric (vectors of double) in binary form. Unfortunately one of the systems is IBM ppc997 and the other is AMD Opteron, It seems the format of binary numbers in these systems are different. I have tried 3 ways till now: 1- Changed my files to ASCII format (i.e. saved a number at each line in a text file), sent them to the destination and changed them again to binary on the target system (they both are UNIX, no end of line character difference??!) 2- Sent pure binaries to the destination 3- used uuencode sent them to the destination and decoded them Unfortunately any of these methods does not work (my code in the destination system generates garbage, while it works on the first system, I'm 100% sure the code itself is portable). I don't know what else I can do? Do you have any idea? I'm not a professional, please don't use computer scientists terminology! And: my codes are in C, so by binary I mean a one to one mapping between memory and hard disk. Thanks

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  • Doesn't (didn't) Scala have automatically generated setters?

    - by Malvolio
    Google and my failing memory are both giving me hints that it does, but every attempt is coming up dry. class Y { var y = 0 } var m = new Y() m.y_(3) error: value y_ is not a member of Y Please tell me I am doing something wrong. (Also: please tell me what it is I am doing wrong.) EDIT The thing I am not doing wrong, or at least not the only thing I am doing wrong, is the way I am invoking the setter. The following things also fail, all with the same error message: m.y_ // should be a function valued expression m.y_ = (3) // suggested by Google and by Mchl f(m.y_) // where f takes Int => Unit as an argument f(m.y) // complains that I am passing in Int not a function I am doing this all through SimplyScala, because I'm too lazy and impatient to set up Scala on my tiny home machine. Hope it isn't that... And the winner is ... Fabian, who pointed out that I can't have a space between the _ and the =. I thought out why this should be and then it occurred to me: The name of the setter for y is not y_, it is y_= ! Observe: class Y { var y = 0 } var m = new Y() m.y_=(3) m.y res1: Int = 3 m.y_= error: missing arguments for method y_= in class Y; follow this method with `_` if you want to treat it as a partially applied function m.y_= ^ m.y_=_ res2: (Int) => Unit = def four(f : Int => Unit) = f(4) four(m.y_=) m.y res3: Int = 4 Another successful day on StackExchange.

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  • Outlook VSTO AddIn for Meetings

    - by BigDubb
    We have created a VSTO addin for Outlook Meetings. As part of this we trap on the SendEvent of the message on the FormRegionShowing event: _apptEvents.Send += new Microsoft.Office.Interop.Outlook.ItemEvents_SendEventHandler(_apptEvents_Send); The method _apptEvents_Send then tests on a couple of properties and exits where appropriate. private void _apptEvents_Send(ref bool Cancel) { if (!_Qualified) { MessageBox.Show("Meeting has not been qualified", "Not Qualified Meeting", MessageBoxButtons.OK, MessageBoxIcon.Information); chkQualified.Focus(); Cancel = true; } } The problem that we're having is that some users' messages get sent twice. Once when the meeting is sent and a second time when the user re-opens outlook. I've looked for memory leaks, thinking that something might not be getting disposed of properly, and have added explicit object disposal on all finally calls to try and make sure resources are managed, but still getting the functionality incosistently across the organization. i.e. I never encountered the problem during development, nor other developers during testing. All users are up to date on framework (3.5 SP1) and Hotfixes for Outlook. Does anyone have any ideas on what might be causing this? Any ideas anyone might have would be greatly appreciated.

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  • What happens when modifying Gemfile.lock directly?

    - by Mik378
    Since the second time of bundle install execution, dependencies are loaded from Gemfile.lock when Gemfile isn't changed. But I wonder how detection of changes is made between those two files. For instance, if I'm adding a new dependency directly into Gemfile.lock without adding it into Gemfile (as opposed to the best practice since Gemfile.lock is auto-generated from Gemfile), would a bundle install consider Gemfile as changed ? Indeed, does bundle install process compares the whole Gemfile and Gemfile.lock trees in order to detect changes? If it is, even if I'm adding a dependency directly to Gemfile.lock, Gemfile would be detected as changed (since different) and would re-erase Gemfile.lock (so losing the added dependency...) What is the process of bundle install since the launch for the second time ? To be more clear, my question is: Are changes based only from Gemfile ? That means bundler would keep a Gemfile snapshot of every bundle install execution number N and merely compares it to the bundle install execution N+1 ? Or none snapshot are created in bundler memory and bundler makes a comparison with Gemfile.lock each time to detect if Gemfile must be considered as changed.

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  • Transaction within a Transaction in C#

    - by Rosco
    I'm importing a flat file of invoices into a database using C#. I'm using the TransactionScope to roll back the entire operation if a problem is encountered. It is a tricky input file, in that one row does not necessary equal one record. It also includes linked records. An invoice would have a header line, line items, and then a total line. Some of the invoices will need to be skipped, but I may not know it needs to be skipped until I reach the total line. One strategy is to store the header, line items, and total line in memory, and save everything once the total line is reached. I'm pursuing that now. However, I was wondering if it could be done a different way. Creating a "nested" transaction around the invoice, inserting the header row, and line items, then updating the invoice when the total line is reached. This "nested" transaction would roll back if it is determined the invoice needs to be skipped, but the overall transaction would continue. Is this possible, practical, and how would you set this up?

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  • "for" loop from program 7.6 from Kochan's "Programming in Objective-C"

    - by Mr_Vlasov
    "The sigma notation is shorthand for a summation. Its use here means to add the values of 1/2^i, where i varies from 1 to n. That is, add 1/2 + 1/4 + 1/8 .... If you make the value of n large enough, the sum of this series should approach 1. Let’s experiment with different values for n to see how close we get." #import "Fraction.h" int main (int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; Fraction *aFraction = [[Fraction alloc] init]; Fraction *sum = [[Fraction alloc] init], *sum2; int i, n, pow2; [sum setTo: 0 over: 1]; // set 1st fraction to 0 NSLog (@"Enter your value for n:"); scanf ("%i", &n); pow2 = 2; for (i = 1; i <= n; ++i) { [aFraction setTo: 1 over: pow2]; sum2 = [sum add: aFraction]; [sum release]; // release previous sum sum = sum2; pow2 *= 2; } NSLog (@"After %i iterations, the sum is %g", n, [sum convertToNum]); [aFraction release]; [sum release]; [pool drain]; return 0; } Question: Why do we have to create additional variable sum2 that we are using in the "for" loop? Why do we need "release previous sum" here and then again give it a value that we just released? : sum2 = [sum add: aFraction]; [sum release]; // release previous sum sum = sum2; Is it just for the sake of avoiding memory leakage? (method "add" initializes a variable that is stored in sum2)

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  • Extra NotifyIcon shown in system tray

    - by Kettch19
    I'm having an issue with an app where my NotifyIcon displays an extra icon. The steps to reproduce it are easy, but the problem is that the extra icon shows up after any of the actual codebehind we've added fires. Put simply, clicking a button triggers execution of method FooBar() which runs all the way through fine but its primary duty is to fire a backgroundworker to log into another of our apps. It only appears if this particular button is clicked. Strangely enough, we have a WndProc method override and if I step through until the extra NotifyIcon appears, it always appears during this method so something else beyond the codebehind must be triggering the behavior. Our WndProc method is currently (although I don't think it's caused by the WndProc): Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message) 'Check for WM_COPYDATA message from other app or drag/drop action and handle message If m.Msg = NativeMethods.WM_COPYDATA Then ' get the standard message structure from lparam Dim CD As NativeMethods.COPYDATASTRUCT = m.GetLParam(GetType(NativeMethods.COPYDATASTRUCT)) 'setup byte array Dim B(CD.cbData) As Byte 'copy data from memory into array Runtime.InteropServices.Marshal.Copy(New IntPtr(CD.lpData), B, 0, CD.cbData) 'Get message as string and process ProcessWMCopyData(System.Text.Encoding.Default.GetString(B)) 'empty array Erase B 'set message result to 'true', meaning message handled m.Result = New IntPtr(1) End If 'pass on result and all messages not handled by this app MyBase.WndProc(m) End Sub The only place in the code where the NotifyIcon in question is manipulated at all is in the following event handler (again, don't think this is the culprit, but just for more info): Private Sub TrayIcon_MouseDoubleClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles TrayIcon.MouseDoubleClick If Me.Visible Then Me.Hide() Else PositionBottomRight() Me.Show() End If End Sub The backgroundworker's DoWork is as follows (just a class call to log in to our other app, but again just for info): Private Sub LoginBackgroundWorker_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles LoginBackgroundWorker.DoWork Settings.IsLoggedIn = _wdService.LogOn(Settings.UserName, Settings.Password) End Sub Does anyone else have ideas on what might be causing this or how to possibly further debug this? I've been banging my head on this without seeing a pattern so another set of eyes would be extremely appreciated. :) I've posted this on MSDN winforms forums as well and have had no luck there so far either.

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  • Why do I get "request for member in something not a struct or union" from this code?

    - by pyroxene
    I'm trying to teach myself C by coding up a linked list. I'm new to pointers and memory management and I'm getting a bit confused. I have this code: /* Remove a node from the list and rejiggle the pointers */ void rm_node(struct node **listP, int index) { struct node *prev; struct node *n = *listP; if (index == 0) { *listP = *listP->next; free(n); return; } for (index; index > 0; index--) { n = n->next; if (index == 2) { prev = n; } } prev->next = n->next; free(n); } to remove an element from the list. If I want to remove the first node, I still need some way of referring to the list, which is why the listP arg is a double pointer, so it can point to the first element of the list and allow me to free the node that used to be the head. However, when I try to dereference listP to access the pointer to the next node, the compiler tells me error: request for member ‘next’ in something not a structure or union . What am I doing wrong here? I think I might be hopelessly mixed up..?

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

    - by CM90
    Considering the use of delegates in C#, does anyone know if there is a performance advantage or if it is a convenience to the programmer? If we are creating an object that holds a method, it sounds as if that object would be a constant in memory to be called on, instead of loading the method every time it is called. For example, if we look at the following Unity3D-based code: public delegate H MixedTypeDelegate<G, H>(G g) public class MainParent : MonoBehaviour // Most Unity classes inherit from M.B. { public static Vector3 getPosition(GameObject g) { /* GameObject is a Unity class, and Vector3 is a struct from M.B. The "position" component of a GameObject is a Vector3. This method takes the GameObject I pass to it & returns its position. */ return g.transform.position; } public static MixedTypeDelegate<GameObject, Vector3> PositionOf; void Awake( ) // Awake is the first method called in Unity, always. { PositionOf = MixedTypeDelegate<GameObject, Vector3>(getPosition); } } public class GameScript : MainParent { GameObject g = new GameObject( ); Vector3 whereAmI; void Update( ) { // Now I can say: whereAmI = PositionOf(g); // Instead of: whereAmI = getPosition(g); } } . . . But that seems like an extra step - unless there's that extra little thing that it helps. I suppose the most succinct way to ask a second question would be to say: When you had your aha moment in understanding delegates, what was the context/scenario/source? Thank you!

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  • File upload issue

    - by Varun
    I am working on a PHP based, ticket management system. While creating a ticket, one can upload an attachment. I want to put a limit (say 10 MB) per file upload. To implement this I plan the following- 1. In php.ini set post_max_size = 10M 2.In PHP script which receives the POST- Since the file is larger than post_max_size, $_FILES[] will be empty. But I can still check the content-length header and discard the upload, if size more than 10M. While testing this I tried uploading a file of 1 GB and analysed the http traffic and this is what I found. - the entire 1 GB data is first uploaded to a to the server temporarily and discarded once the http request completes. Though I couldn't exactly find out where the file was getting saved(as it was not there in the temporary directory in the server.), but my http traffic analyzer showed that the browser did send 1 GB data to the server. - the PHP script execution started only after completion of the http request(i.e after uploading the entire 1 GB) Now I have 2 concerns: a) People may exploit my server bandwidth by trying to upload large file, which I will have to discard anyways. b) Even worse, if someone starts uploading a huge file (say 100 GB), entire 100 GB data is first uploaded to the server temporarily, that means for that period, it will consume that much of memory on my server. What's the common solution for this. Am I missing something here?

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  • Drawing line graphics leads Flash to spiral out of control!

    - by drpepper
    Hi, I'm having problems with some AS3 code that simply draws on a Sprite's Graphics object. The drawing happens as part of a larger procedure called on every ENTER_FRAME event of the stage. Flash neither crashes nor returns an error. Instead, it starts running at 100% CPU and grabs all the memory that it can, until I kill the process manually or my computer buckles under the pressure when it gets up to around 2-3 GB. This will happen at a random time, and without any noticiple slowdown beforehand. WTF? Has anyone seen anything like this? PS: I used to do the drawing within a MOUSE_MOVE event handler, which brought this problem on even faster. PPS: I'm developing on Linux, but reproduced the same problem on Windows. UPDATE: You asked for some code, so here we are. The drawing function looks like this: public static function drawDashedLine(i_graphics : Graphics, i_from : Point, i_to : Point, i_on : Number, i_off : Number) : void { const vecLength : Number = Point.distance(i_from, i_to); i_graphics.moveTo(i_from.x, i_from.y); var dist : Number = 0; var lineIsOn : Boolean = true; while(dist < vecLength) { dist = Math.min(vecLength, dist + (lineIsOn ? i_on : i_off)); const p : Point = Point.interpolate(i_from, i_to, 1 - dist / vecLength); if(lineIsOn) i_graphics.lineTo(p.x, p.y); else i_graphics.moveTo(p.x, p.y); lineIsOn = !lineIsOn; } } and is called like this (m_graphicsLayer is a Sprite): m_graphicsLayer.graphics.clear(); if (m_destinationPoint) { m_graphicsLayer.graphics.lineStyle(2, m_fixedAim ? 0xff0000 : 0x333333, 1); drawDashedLine(m_graphicsLayer.graphics, m_initialPos, m_destinationPoint, 10, 10); }

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  • std::map keys in C++

    - by Soumava
    I have a requirement to create two different maps in C++. The Key is of type CHAR * and the Value is a pointer to a struct. I am filling 2 maps with these pairs, in separate iterations. After creating both maps I need find all such instances in which the value of the string referenced by the CHAR * are same. For this i am using the following code : typedef struct _STRUCTTYPE { .. } STRUCTTYPE, *PSTRUCTTYPE; typedef pair {CHAR *,PSTRUCTTYPE} kvpair; .. CHAR *xyz; PSTRUCTTYPE abc; after filling the information; Map.insert (kvpair(xyz,abc)); the above is repeated x times for the first map, and y times for the second map. after both are filled out; std::map {CHAR *, PSTRUCTTYPE} :: iterator Iter,findIter; for (Iter=iteratedMap-begin();Iter!=iteratedMap-end();mapIterator++) { char *key = Iter-first; printf("%s\n",key); findIter=otherMap-find(key); //printf("%u",findIter-second); if (findIter!=otherMap-end()) { printf("Match!\n"); } } The above code does not show any match, although the list of keys in both maps show obvious matches. My understanding is that the equals operator for CHAR * just equates the memory address of the pointers. My question is, what should i do to alter the equals operator for this type of key or could I use a different datatype for the string? *note : {} has been used instead of angle brackets as the content inside angle brackets was not showing up in the post.

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  • Does IE completely ignore cache control headers for AJAX requests?

    - by Joshua Hayworth
    Hello there, I've got, what I would consider, a simple test web site. A single page with a single button. Here is a copy of the source I'm working with if you would like to download it and play with it. When that button is clicked, it creates a JavaScript timer that executes once a second. When the timer function is executed, An AJAX call is made to retrieve a text value. That text value is then placed into the DOM. What's my problem? IE Caching. Crack open Task Manager and watch what happens to the iexplorer.exe process (IE 8.0.7600.16385 for me) while the timer in that page is executing. See the memory and handle count getting larger? Why is that happening when, by all accounts, I have caching turned off. I've got the jQuery cache option set to false in $.ajaxSetup. I've got the CacheControl header set to no-cache and no-store. The Expires header is set to DateTime.Now.AddDays(-1). The headers are set in both the page code-behind as well as the HTTP Handler's response. Anybody got any ideas as to how I could prevent IE from caching the results of the AJAX call? Here is what the iexplorer.exe process looks like in ProcessMonitor. I believe that the activity shown in this picture is exactly what I'm attempting to prevent.

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  • Gtk: How can I get a part of a file in a textview with scrollbars relating to the full file

    - by badgerman1
    I'm trying to make a very large file editor (where the editor only stores a part of the buffer in memory at a time), but I'm stuck while building my textview object. Basically- I know that I have to be able to update the text view buffer dynamically, and I don't know hot to get the scrollbars to relate to the full file while the textview contains only a small buffer of the file. I've played with Gtk.Adjustment on a Gtk.ScrolledWindow and ScrollBars, but though I can extend the range of the scrollbars, they still apply to the range of the buffer and not the filesize (which I try to set via Gtk.Adjustment parameters) when I load into textview. I need to have a widget that "knows" that it is looking at a part of a file, and can load/unload buffers as necessary to view different parts of the file. So far, I believe I'll respond to the "change_view" to calculate when I'm off, or about to be off the current buffer and need to load the next, but I don't know how to get the scrollbars to have the top relate to the beginning of the file, and the bottom relate to the end of the file, rather than to the loaded buffer in textview. Any help would be greatly appreciated, thanks!

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  • Question on passing a pointer to a structure in C to a function?

    - by worlds-apart89
    Below, I wrote a primitive singly linked list in C. Function "addEditNode" MUST receive a pointer by value, which, I am guessing, means we can edit the data of the pointer but can not point it to something else. If I allocate memory using malloc in "addEditNode", when the function returns, can I see the contents of first-next ? Second question is do I have to free first-next or is it only first that I should free? I am running into segmentation faults on Linux. #include <stdio.h> #include <stdlib.h> typedef struct list_node list_node_t; struct list_node { int value; list_node_t *next; }; void addEditNode(list_node_t *node) { node->value = 10; node->next = (list_node_t*) malloc(sizeof(list_node_t)); node->next->value = 1; node->next->next = NULL; } int main() { list_node_t *first = (list_node_t*) malloc(sizeof(list_node_t)); first->value = 1; first->next = NULL; addEditNode(first); free(first); return 0; }

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  • C# cross thread dialogue co-operation

    - by John Attridge
    K I am looking at a primarily single thread windows forms application in 3.0. Recently my boss had a progress dialogue added on a separate thread so the user would see some activity when the main thread went away and did some heavy duty work and locked out the GUI. The above works fine unless the user switches applications or minimizes as the progress form sits top most and will not disappear with the main application. This is not so bad if there are lots of little operations as the event structure of the main form catches up with its events when it gets time so minimized and active flags can be checked and thus the dialog thread can hide or show itself accordingly. But if a long running sql operation kicks off then no events fire. I have tried intercepting the WndProc command but this also appears queued when a long running sql operation is executing. I have also tried picking up the processes, finding the current app and checking various memory values isiconic and the like inside the progress thread but until the sql operation finishes none of these get updated. Removing the topmost causes the dialog to disappear when another app activates but if the main app is then brought back it does not appear again. So I need a way to find out if the other thread is minimized or no longer active that does not involve querying the actual thread as that locks until the sql operation finishes. Now I know that this is not the best way to write this and it would be better to have all the heavy processing on separate threads leaving the GUI free but as this is a huge ancient legacy app the time to re-write in that fashion will not be provided so I have to work with what I have got. Any help is appreciated

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  • GUI for server-client program

    - by sksingh73
    I am making a server-client application in c++. In this i am also using shared memory & file read-write operations. my program is completely ready & i now wants to make a gui for it. someone suggested me to go for QT4, but when i tried it, i found i have to re-write 80% of the code because QT has got its own classes & variable. i don't want to do it. i want suggestions from you on this regard. my requirements for gui are very simple i.e there will be a main form, which will have two text boxes in which all messages being sent & received by client & server should be shown. there should be another lineedit box, through which i can send the messages to the other end server. I don't know how to make this gui. someone suggested tcl/tk, other suggested me use php/swig. i am not sure how to go about this. my only requirement is that i want to make this simple gui with minimum of changes in my code. THANX

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  • Python 2.6 does not like appending to existing archives in zip files

    - by user313661
    Hello, In some Python unit tests of a program I'm working on we use in-memory zipfiles for end to end tests. In SetUp() we create a simple zip file, but in some tests we want to overwrite some archives. For this we do "zip.writestr(archive_name, zip.read(archive_name) + new_content)". Something like import zipfile from StringIO import StringIO def Foo(): zfile = StringIO() zip = zipfile.ZipFile(zfile, 'a') zip.writestr( "foo", "foo content") zip.writestr( "bar", "bar content") zip.writestr( "foo", zip.read("foo") + "some more foo content") print zip.read("bar") Foo() The problem is that this works fine in Python 2.4 and 2.5, but not 2.6. In Python 2.6 this fails on the print line with "BadZipfile: File name in directory "bar" and header "foo" differ." It seems that it is reading the correct file bar, but that it thinks it should be reading foo instead. I'm at a loss. What am I doing wrong? Is this not supported? I tried searching the web but could find no mention of similar problems. I read the zipfile documentation, but could not find anything (that I thought was) relevant, especially since I'm calling read() with the filename string. Any ideas? Thank you in advance!

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  • Need help getting parent reference to child view controller

    - by Andy
    I've got the following code in one of my view controllers: - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { switch (indexPath.section) { case 0: // "days" section tapped { DayPicker *dayPicker = [[DayPicker alloc] initWithStyle:UITableViewStylePlain]; dayPicker.rowLabel = self.activeDaysLabel; dayPicker.selectedDays = self.newRule.activeDays; [self.navigationController pushViewController:dayPicker animated:YES]; [dayPicker release]; break; ... Then, in the DayPicker controller, I do some stuff to the dayPicker.rowLabel property. Now, when the dayPicker is dismissed, I want the value in dayPicker.rowLabel to be used as the cell.textLabel.text property in the cell that called the controller in the first place (i.e., the cell label becomes the option that was selected within the DayPicker controller). I thought that by using the assignment operator to set dayPicker.rowLabel = self.activeDaysLabel, the two pointed to the same object in memory, and that upon dismissing the DayPicker, my first view controller, which uses self.activeDaysLabel as the cell.textLabel.text property for the cell in question, would automagically pick up the new value of the object. But no such luck. Have I missed something basic here, or am I going about this the wrong way? I originally passed a reference to the calling view controller to the child view controller, but several here told me that was likely to cause problems, being a circular reference. That setup worked, though; now I'm not sure how to accomplish the same thing "the right way." As usual, thanks in advance for your help.

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  • Why does a MFC application behaves mysteriously in encrypted hard drive environment.

    - by MauriceL
    I'm working on a bug where I have an MFC application that does weird things when installed in when Sophos Safeguard hard drive encryption is installed. I'm sorry to be so vague here, but I'm writing this away from the office so this is all from my (poor) memory. Three things I've noticed: AfxGetResourceHandle() doesn't return a consistent resource handle. There is a single case where we try to load a string resource, and for some reason, the resource handle that we get from this method is different to all the other stings. Can't construct a CDocumentTemplate. There is a trace error which I cant seem to recall. Will edit and post when I'm in tomorrow. This behaviour appears to manifest in a Visual Studio 2005 version of the project, but not a Visual Studio 2008 version. Unfortunately moving to the 2008 version is not an option. The bug is not always reproducable if I step through with a debugger. Also, bringing up debug message boxes changes the behaviuor, which leads me to think that either there is some kind of race condition going on with the way MFC events are being handled, but I'm not sure how I'll ever know for sure, or even what I can do about it if I did. I think there's some underlying reason that the app is behaving weirdly, but what I've posted are more symptoms. Can anyone think of what I should check for? I've run Windows update on the test environment to ensure everything was up to date, and I've examined the process in procmon to see if the disk encryption stuff was getting in the way and conflicting with files - it didn't appear to be, but it does appear to be involved in some way as our app accesses Sophos related paths in the temp directory.

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  • Caching vector addition over changing collections

    - by DRMacIver
    I have the following setup: I have a largish number of uuids (currently about 10k but expected to grow unboundedly - they're user IDs) and a function f : id - sparse vector with 32-bit integer values (no need to worry about precision). The function is reasonably expensive (not outrageously so, but probably on the order of a few 100ms for a given id). The dimension of the sparse vectors should be assumed to be infinite, as new dimensions can appear over time, but in practice is unlikely to ever exceed about 20k (and individual results of f are unlikely to have more than a few hundred non-zero values). I want to support the following operations efficiently: add a new ID to the collection invalidate an existing ID retrieve sum f(id) in O(changes since last retrieval) i.e. I want to cache the sum of the vectors in a way that's reasonable to do incrementally. One option would be to support a remove ID operation and treat invalidation as a remove followed by an add. The problem with this is that it requires us to keep track of all the old values of f, which is expensive in space. I potentially need to use many instances of this sort of cached structure, so I would like to avoid that. The likely usage pattern is that new IDs are added at a fairly continuous rate and are frequently invalidated at first. Ids which have been invalidated recently are much more likely to be invalidated again than ones which have remained valid for a long time, but in principle an old Id can still be invalidated. Ideally I don't want to do this in memory (or at least I want a way that lets me save the result to disk efficiently), so an idea which lets me piggyback off an existing DB implementation of some sort would be especially appreciated.

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  • Pointer and malloc issue

    - by Andy
    I am fairly new to C and am getting stuck with arrays and pointers when they refer to strings. I can ask for input of 2 numbers (ints) and then return the one I want (first number or second number) without any issues. But when I request names and try to return them, the program crashes after I enter the first name and not sure why. In theory I am looking to reserve memory for the first name, and then expand it to include a second name. Can anyone explain why this breaks? Thanks! #include <stdio.h> #include <stdlib.h> void main () { int NumItems = 0; NumItems += 1; char* NameList = malloc(sizeof(char[10])*NumItems); printf("Please enter name #1: \n"); scanf("%9s", NameList[0]); fpurge(stdin); NumItems += 1; NameList = realloc(NameList,sizeof(char[10])*NumItems); printf("Please enter name #2: \n"); scanf("%9s", NameList[1]); fpurge(stdin); printf("The first name is: %s",NameList[0]); printf("The second name is: %s",NameList[1]); return 0; }

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  • Parallel doseq for Clojure

    - by andrew cooke
    I haven't used multithreading in Clojure at all so am unsure where to start. I have a doseq whose body can run in parallel. What I'd like is for there always to be 3 threads running (leaving 1 core free) that evaluate the body in parallel until the range is exhausted. There's no shared state, nothing complicated - the equivalent of Python's multiprocessing would be just fine. So something like: (dopar 3 [i (range 100)] ; repeated 100 times in 3 parallel threads... ...) Where should I start looking? Is there a command for this? A standard package? A good reference? So far I have found pmap, and could use that (how do I restrict to 3 at a time? looks like it uses 32 at a time - no, source says 2 + number of processors), but it seems like this is a basic primitive that should already exist somewhere. clarification: I really would like to control the number of threads. I have processes that are long-running and use a fair amount of memory, so creating a large number and hoping things work out OK isn't a good approach (example which uses a significant chunk available mem). update: Starting to write a macro that does this, and I need a semaphore (or a mutex, or an atom i can wait on). Do semaphores exist in Clojure? Or should I use a ThreadPoolExecutor? It seems odd to have to pull so much in from Java - I thought parallel programming in Clojure was supposed to be easy... Maybe I am thinking about this completely the wrong way? Hmmm. Agents?

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