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  • Memory Barrier by lock statement

    - by jalalaldeen
    I read recently about memory barrier and the reordaring issue and now I have some confusion about it. Let us have a following senario: private object _object1 = null; private object _object2 = null; private bool _usingObject1 = false; private object MyObject { get { if (_usingObject1) { return _object1; } else { return _object2; } } set { if (_usingObject1) { _object1 = value; } else { _object2 = value; } } } private void Update() { _usingMethod1 = true; SomeProperty = FooMethod(); //.. _usingMethod1 = false; } 1- At Update method; is it always _usingMethod1 = true statement excecuted before getting or setting the property? or due reordaring issue we can not garantee that? 2- Should we use volitle like. private volitle bool _usingMethod1 = false; 3- If we use lock; can we garantee then every statement within the lock will be excecuted in order like: private void FooMethod() { object locker = new object(); lock (locker) { x = 1; y = a; i++; } } Thanks in advanced..

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  • Clarification on ZVals

    - by Beachhouse
    I was reading this: http://www.dereleased.com/2011/04/27/the-importance-of-zvals-and-circular-references/ And there's an example that lost me a bit. $foo = &$bar; $bar = &$foo; $baz = 'baz'; $foo = &$baz; var_dump($foo, $bar); /* string(3) "baz" NULL */ If you’ve been following along, this should make perfect sense. $foo is created, and pointed at a ZVal location identified by $bar; when $bar is created, it points at the same place $foo was pointed. That location, of course, is null. When $foo is reassigned, the only thing that changes is to which ZVal $foo points; if we had assigned a different value to $foo first, then $bar would still retain that value. I learned to program in C. I understand that PHP is different and it uses ZVals instead of memory locations as references. But when you run this code: $foo = &$bar; $bar = &$foo; It seems to me that there would be two ZVals. In C there would be two memory locations (and the values would be of the opposite memory location). Can someone explain?

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  • should i move the config file from codeigniter directory

    - by Patrick
    I've just published my site, created with codeigniter. the entire directory is in my public folder, including the config file (in public/system/application/config). I just wanted to double check: do I have to move this file to another, non public, directory? I think codeigniter doesn't allow any direct access, but I am not 100% sure.. thanks, P.

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  • Testing for optional node - Delphi XE

    - by Seti Net
    What is the proper way to test for the existance of an optional node? A snipped of my XML is: <Antenna > <Mount Model="text" Manufacture="text"> <BirdBathMount/> </Mount> </Antenna> But it could also be: <Antenna > <Mount Model="text" Manufacture="text"> <AzEl/> </Mount> </Antenna> The child of Antenna could either be BirdBath or AzEl but not both... In Delphi XE I have tried: if (MountNode.ChildNodes.Nodes['AzEl'] <> unassigned then //Does not work if (MountNode.ChildNodes['BirdBathMount'].NodeValue <> null) then // Does not work if (MountNode.BirdBathMount.NodeValue <> null) then // Does not work I use XMLSpy to create the schema and the example XML and they parse correctly. I use Delphi XE to create the bindings and it works on most other combinations fine. This must have a simple answer that I have just overlooked - but what? Thanks...... Jim

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  • How do you deal with breaking changes in a Rails migration?

    - by Adam Lassek
    Let's say I'm starting out with this model: class Location < ActiveRecord::Base attr_accessible :company_name, :location_name end Now I want to refactor one of the values into an associated model. class CreateCompanies < ActiveRecord::Migration def self.up create_table :companies do |t| t.string :name, :null => false t.timestamps end add_column :locations, :company_id, :integer, :null => false end def self.down drop_table :companies remove_column :locations, :company_id end end class Location < ActiveRecord::Base attr_accessible :location_name belongs_to :company end class Company < ActiveRecord::Base has_many :locations end This all works fine during development, since I'm doing everything a step at a time; but if I try deploying this to my staging environment, I run into trouble. The problem is that since my code has already changed to reflect the migration, it causes the environment to crash when it attempts to run the migration. Has anyone else dealt with this problem? Am I resigned to splitting my deployment up into multiple steps?

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  • C# keyhook question

    - by user203123
    I copied the following code from http://www.codeproject.com/KB/cs/CSLLKeyboardHook.aspx, public int hookProc(int code, int wParam, ref keyboardHookStruct lParam) { if (code >= 0) { Keys key = (Keys)lParam.vkCode; if (HookedKeys.Contains(key)) { KeyEventArgs kea = new KeyEventArgs(key); if((wParam == WM_KEYDOWN || wParam == WM_SYSKEYDOWN) && (KeyDown != null)) {KeyDown(this, kea) ;} else if ((wParam == WM_KEYUP || wParam == WM_SYSKEYUP) && (KeyUp != null)) {KeyUp(this, kea); } if (kea.Handled) {return 1;} } } lParam.vkCode ++; lParam.scanCode ++; return CallNextHookEx(hhook, code, wParam, ref lParam); } It works fine but when I make a little change: lParam.vkCode ++; or lParam.scanCode ++; right before the return CallNextHookEx(...), the original keys still appears in Notepad. Ex. If I press "a", I expect the letter in Notepad will be "b" but it still "a". It seems like "lParam" doesn't change. Couldn't understand why?

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  • Query to bring count from comma seperated Value

    - by Mugil
    I have Two Tables One for Storing Products and Other for Storing Orders List. CREATE TABLE ProductsList(ProductId INT NOT NULL PRIMARY KEY, ProductName VARCHAR(50)) INSERT INTO ProductsList(ProductId, ProductName) VALUES(1,'Product A'), (2,'Product B'), (3,'Product C'), (4,'Product D'), (5,'Product E'), (6,'Product F'), (7,'Product G'), (8,'Product H'), (9,'Product I'), (10,'Product J'); CREATE TABLE OrderList(OrderId INT NOT NULL PRIMARY KEY AUTO_INCREMENT, EmailId VARCHAR(50), CSVProductIds VARCHAR(50)) SELECT * FROM OrderList INSERT INTO OrderList(EmailId, CSVProductIds) VALUES('[email protected]', '2,4,1,5,7'), ('[email protected]', '5,7,4'), ('[email protected]', '2'), ('[email protected]', '8,9'), ('[email protected]', '4,5,9'), ('[email protected]', '1,2,3'), ('[email protected]', '9,10'), ('[email protected]', '1,5'); Output ItemName NoOfOrders Product A 4 Product B 3 Product C 1 Product D 3 Product E 4 Product F 0 Product G 2 Product H 1 Product I 2 Product J 1 The Order List Stores the ItemsId as Comma separated value for every customer who places order.Like this i am having more than 40k Records in my dB table Now I am assigned with a task of creating report in which I should display Items and No of People ordered Items as Shown Below I Used Query as below in my PHP to bring the Orders One By One and storing in array. SELECT COUNT(PL.EmailId) FROM OrderList PL WHERE CSVProductIds LIKE '2' OR CSVProductIds LIKE '%,2,%' OR CSVProductIds LIKE '%,2' OR CSVProductIds LIKE '2,%'; 1.Is it possible to get the same out put by using Single Query 2.Does using a like in mysql query slows down the dB when the table has more no of records i.e 40k rows

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  • Javascript dynamic table memory usage

    - by Dan
    I use a dynamic table: <html> <body> <button id="button">Build table</button> <div id="container"> <script type="text/javascript"> window.onload=function(){ var table = null; var row = "<tr><td>111111111111111111111111111111111111111111111111111111</td>" + "<td>222222222222222222222222222222222222222222222222222222</td>" + "<td>333333333333333333333333333333333333333333333333333333</td></tr>"; var data = null; for (var i = 0; i < 2000; i++){ data += row; } var obj = document.getElementById("button"); obj.onclick=function buildTable(){ document.getElementById("container").innerHTML = "<div><table><tbody>" + data + "</tbody></table></div>"; }; }; </script> </body> </html> Using chromes task manager, each time new data is loaded the memory usage increases considerably and doesn't go down, so after some time the app consumes a lot of memory and requires the browser to be closed. Is there any change in the code I can use to solve this or is it a browser side problem?

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  • Grails - how to save a domain object inside a Service ?

    - by w-
    I have a service and inside one of the functions i'm creating a domain object and trying to save it. when it gets to the save part, i get the error No Hibernate Session bound to thread, and configuration does not allow creation of non-transactional one here What do i need to do in order to save a domain object inside of a service. everything on the internet makes it look like this should just work....

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  • Ajax Code to run PHP query After Facebook Like Button is Clicked

    - by John
    I have the PHP below on a file called fblike.php. On another file, I have the Facebook Like button. The Like button functions. I would like to run the code below when the Facebook Like button is clicked. I know that FB.Event.subscribe('edge.create', function(response) {} is supposed to run whenever the Like button is clicked. I know that I am probably supposed to use Javascript and maybe Ajax to cause the PHP on fblike.php to run. But after multiple tries, I can't get it to work. What is the specific Ajax code that I could include within the Facebook Event? Do I need to do anything to the Like button code to allow the Facebook Event to work? $submissionid = $_POST['submissionid']; $uid = $_POST['uid']; mysql_connect("server", "username", "password") or die(mysql_error()); mysql_select_db("database") or die(mysql_error()); $q = "INSERT INTO fblikes VALUES (NULL, '$submissionid', '$uid', NULL)"; $r = mysql_query($q); if($r) { echo "Success!"; } elseif(!$r) { echo "Failed!"; }

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  • PHP function to handle most database queries has a problem with results. I am getting the right numb

    - by asdasds
    Here is my little function. It does not handle the results correctly. I do get all the rows that I want, but all the rows of the $results array contain the exact same values. So i make 2 arrays, a temporary array to hold the values after each fetch, and another array to hold all the temporary arrays. First i take the temp array and map its keys to the column names. Then i give it to bind_result, and call fetch() and use it like I would any other result value. Could this be because I re-use the $results array? numresults is the number of values you are taking from each row. if 0, you are not getting any results back. function db_query($db, $query, $params = NULL, $numresults = 0) { if($stmt = $db -> prepare($query)) { if($params != NULL) { call_user_func_array(array($stmt, 'bind_param'), $params); } if(!$stmt -> execute()) { //echo 'exec error:',$db->error; return false; } if($numresults > 0) { $results = array(); $tmpresult = array(); $meta = $stmt->result_metadata(); while ($columnName = $meta->fetch_field()) $tmpresult[] = &$results[$columnName->name]; call_user_func_array(array($stmt, 'bind_result'), $tmpresult); $meta->close(); $results = array(); while($stmt -> fetch()) $results[] = $tmpresult; } $stmt -> close(); } else { //echo 'prepare error: ',$db->error; return false; } if($numresults == 0) return true; return $results; }

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  • Using Java, Need to establish an https connection via proxy.

    - by Zombies
    I need to establish and send/read over/from an https connection (to a website of course) but through an http proxy or SOCKS proxy. A few other requirements supports blocking (I can't use non-blocking/nio) isn't set as an environment or some other global scope property (there are multiple threads accessing) I was looking into HttpCore components but I did not see any support for blocking https.

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  • Difference between [object variable] and object.variable in Obj-C?

    - by John Smith
    I was working on a program today and hit this strange bug. I had a UIButton with an action assigned. The action was something like: -(void) someaction:(id) e { if ([e tag]==SOMETAG) { //dostuff } } What confuses me is that when I first wrote it, the if line was if (e.tag==SOMETAG) XCode refused to compile it, saying error: request for member 'tag' in 'e', which is of non-class type 'objc_object*' but I thought the two were equivalent. So under what circumstances are they not the same?

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  • Will releasing an iPhone app makes it available for iPad by default?

    - by agro1986
    In my XCode's Targets summary screen, the "Devices" drop down is set to "iPhone" (other possible values are iPad and Universal) because I haven't fine tuned the app's UI for iPad. However, will people be able to download and run my app from the iPad in non-fullscreen? (e.g., with black border surrounding most of the screen) I want people to be able to search for it in app store, install it, and run it even though it is not full screen. Thanks a lot

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  • How should a multi-threaded C application handle a failed malloc()?

    - by user294463
    A part of an application I'm working on is a simple pthread-based server that communicates over a TCP/IP socket. I am writing it in C because it's going to be running in a memory constrained environment. My question is: what should the program do if one of the threads encounters a malloc() that returns NULL? Possibilities I've come up with so far: No special handling. Let malloc() return NULL and let it be dereferenced so that the whole thing segfaults. Exit immediately on a failed malloc(), by calling abort() or exit(-1). Assume that the environment will clean everything up. Jump out of the main event loop and attempt to pthread_join() all the threads, then shut down. The first option is obviously the easiest, but seems very wrong. The second one also seems wrong since I don't know exactly what will happen. The third option seems tempting except for two issues: first, all of the threads need not be joined back to the main thread under normal circumstances and second, in order to complete the thread execution, most of the remaining threads will have to call malloc() again anyway. What shall I do?

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  • final fields and thread-safety

    - by pcjuzer
    Should it be all fields, including super-fields, of a purposively immutable java class 'final' in order to be thread-safe or is it enough to have no modifier methods? Suppose I have a POJO with non-final fields where all fields are type of some immutable class. This POJO has getters-setters, and a constructor wich sets some initial value. If I extend this POJO with knocking out modifier methods, thus making it immutable, will extension class be thread-safe?

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  • Using rowDiffs() to calculate difference in values in matrix

    - by user1723765
    I'm using the rowDiffs() command to calculate the step by step difference in 116 rows in a matrix. I get the following error: Error in r[i1] - r[-length(r):-(length(r) - lag + 1L)] : non-numeric argument to binary operator I have no idea why this is happening. I could take the diff() separately for each row and it would work. Any ideas? Here's the data: https://dl.dropbox.com/u/22681355/data.csv Code: a=rowDiffs(data)

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  • [Scala] Using overloaded, typed methods on a collection

    - by stephanos
    I'm quite new to Scala and struggling with the following: I have database objects (type of BaseDoc) and value objects (type of BaseVO). Now there are multiple convert methods (all called 'convert') that take an instance of an object and convert it to the other type accordingly. For example: def convert(doc: ClickDoc): ClickVO = doc match { case null => null case _ => val result = new ClickVO result.x = doc.x result.y = doc.y result } Now I sometimes need to convert a list of objects. How would I do this - I tried: def convert[D <: MyBaseDoc, V <: BaseVO](docs: List[D]):List[V] = docs match { case List() => List() case xs => xs.map(doc => convert(doc)) } Which results in 'overloaded method value convert with alternatives ...'. I tried to add manifest information to it, but couldn't make it work. I couldn't even create one method for each because it'd say that they have the same parameter type after type erasure (List). Ideas welcome!

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  • C# property ending with ?

    - by MicMit
    What does that mean ? public bool? Verbose { get; set; } When applied to string? , there is an error Error 11 The type 'string' must be a non-nullable value type in order to use it as parameter 'T' in the generic type or method 'System.Nullable'

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  • Program that edits string and prints each word individually with C

    - by Michael_19
    I keep getting the error segmentation fault (core dumped) when I run my progam. #include<stdio.h> #include<stdlib.h> int nextword(char *str); int main(void) { char str[] = "Hello! Today is a beautiful day!!\t\n"; int i = nextword(str); while(i != -1) { printf("%s\n",&(str[i])); i = nextword(NULL); } return 0; } int nextword(char *str) { // create two static variables - these stay around across calls static char *s; static int nextindex; int thisindex; // reset the static variables if (str != NULL) { s = str; thisindex = 0; // TODO: advance this index past any leading spaces while (s[thisindex]=='\n' || s[thisindex]=='\t' || s[thisindex]==' ' ) thisindex++; } else { // set the return value to be the nextindex thisindex = nextindex; } // if we aren't done with the string... if (thisindex != -1) { nextindex = thisindex; // TODO: two things // 1: place a '\0' after the current word // 2: advance nextindex to the beginning // of the next word while (s[nextindex] != ' ' && s[nextindex] != '\0') nextindex++; str[nextindex] = '\0'; nextindex++; } return thisindex; } The goal of the program is to print each word in the string str[] to the console on a new line. I am a beginning programmer and this is an assignment so I must use this type of format (no string library allowed). I just would like to know where I went wrong and how I can fix it.

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  • possible to create custom scrollbar graphics without flash?

    - by Joel
    A friend is wanting me to help her convert her flash based website to html. She has an embedded textbox with a scrollbar that is using a flower instead of a normal scrollbar. Avoiding the obvious question of why a user would want a non-standard element to do this task, is it possible to do this without flash?

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  • EMSA_PSS_ENCODE with libssl

    - by luiss
    Hi I'm trying to use libssl to get some EMSA_PSS_ENCRODING through the function RSA_padding_add_PKCS1_type1 in libssl, but I can't find nor docs nor solutions, so this is the example code I've written: #include <stdio.h> #include <stdlib.h> #include <string.h> #include <openssl/rsa.h> #include <openssl/err.h> FILE *error_file; int main() { int lSize; const unsigned char *string1= (unsigned char *)"The pen is on the table"; unsigned char *stringa=NULL; int num = 64; if ((stringa = (unsigned char *)OPENSSL_malloc(num)) == NULL) fprintf(stderr,"OPENSSL_malloc error\n"); fprintf(stdout,"string1 len is %u\n",lSize); if(RSA_padding_add_PKCS1_type_1(stringa,num,string1,lSize) != 1) fprintf(stderr,"Error: RSA_PADDING error\n"); error_file = fopen("libssl.log", "w"); ERR_print_errors_fp(error_file); fclose(error_file); fprintf(stdout,(char *)stringa); fprintf(stdout,"\n"); } The problem is that I get no output in stringa, I think the function RSA_padding_add.. should be initialized, but I can't find how to do it in the few doc at the openssl site. Thanks

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