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• Using memory-based cache together with conventional cache

  - by Industrial

  Hi! Here's the deal. We would have taken the complete static html road to solve performance issues, but since the site will be partially dynamic, this won't work out for us. What we have thought of instead is using memcache + eAccelerator to speed up PHP and take care of caching for the most used data. Here's our two approaches that we have thought of right now: Using memcache on all<< major queries and leaving it alone to do what it does best. Usinc memcache for most commonly retrieved data, and combining with a standard harddrive-stored cache for further usage. The major advantage of only using memcache is of course the performance, but as users increases, the memory usage gets heavy. Combining the two sounds like a more natural approach to us, even though the theoretical compromize in performance. Memcached appears to have some replication features available as well, which may come handy when it's time to increase the nodes. What approach should we use? - Is it stupid to compromize and combine the two methods? Should we insted be focusing on utilizing memcache and instead focusing on upgrading the memory as the load increases with the number of users? Thanks a lot!

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• C: Proper syntax for allocating memory using pointers to pointers.

  - by ~kero-05h

  This is my first time posting here, hopefully I will not make a fool of myself. I am trying to use a function to allocate memory to a pointer, copy text to the buffer, and then change a character. I keep getting a segfault and have tried looking up the answer, my syntax is probably wrong, I could use some enlightenment. /* My objective is to pass a buffer to my Copy function, allocate room, and copy text to it. Then I want to modify the text and print it.*/ #include <stdio.h> #include <stdlib.h> #include <string.h> int Copy(char **Buffer, char *Text); int main() { char *Text = malloc(sizeof(char) * 100); char *Buffer; strncpy(Text, "1234567890\n", 100); Copy(&Buffer, Text); } int Copy(char **Buffer, char *Text) { int count; count = strlen(Text)+1; *Buffer = malloc(sizeof(char) * count); strncpy(*Buffer, Text, 5); *Buffer[2] = 'A'; /* This results in a segfault. "*Buffer[1] = 'A';" results in no differece in the output. */ printf("%s\n", *Buffer); }

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• What's the boost way to create a functor that binds out an argument

  - by Mordachai

  I have need for a function pointer that takes two arguments and returns a string. I would like to pass an adapter that wraps a function that takes one argument, and returns the string (i.e. discard one of the arguments). I can trivially build my own adapter, that takes the 2 arguments, calls the wrapped function passing just the one argument through. But I'd much rather have a simple way to create an adapter on the fly, if there is an easy way to do so in C++/boost? Here's some details to make this a bit more concrete: typedef boost::function<CString (int,int)> TooltipTextFn; class MyCtrl { public: MyCtrl(TooltipTextFn callback = boost::bind(&MyCtrl::GetCellText, this, _1, _2)) : m_callback(callback) { } // QUESTION: how to trivially wrapper GetRowText to conform to TooltipTextFn by just discarding _2 ?! void UseRowText() { m_callback = boost::bind(&MyCtrl::GetRowText, this, _1, ??); } private: CString GetCellText(int row, int column); CString GetRowText(int row); TooltipTextFn m_callback; } Obviously, I can supply a member that adapts GetRowText to take two arguments and only passes the first to GetRowText() itself. But is there already a boost binder / adapter that lets me do that?

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• How is it legal to reference an undefined type inside a structure?

  - by paxdiablo

  As part of answering another question, I came across a piece of code like this, which gcc compiles without complaint. typedef struct { struct xyz *z; } xyz; int main (void) { return 0; } This is the means I've always used to construct types that point to themselves (e.g., linked lists) but I've always thought you had to name the struct so you could use self-reference. In other words, you couldn't use xyz *z within the structure because the typedef is not yet complete at that point. But this particular sample does not name the structure and it still compiles. I thought originally there was some black magic going on in the compiler that automatically translated the above code because the structure and typedef names were the same. But this little beauty works as well: typedef struct { struct NOTHING_LIKE_xyz *z; } xyz; What am I missing here? This seems a clear violation since there is no struct NOTHING_LIKE_xyz type defined anywhere. When I change it from a pointer to an actual type, I get the expected error: typedef struct { struct NOTHING_LIKE_xyz z; } xyz; qqq.c:2: error: field `z' has incomplete type Also, when I remove the struct, I get an error (parse error before "NOTHING ...). Is this allowed in ISO C?

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• Jquery draggable not working in chrome/safari

  - by jbatson

  I have created a page that uses ajax calls to load product images. The jquery code for drag, drop and clone would not work when in the index.php page so I moved it to the page that gets called to request the products as each product has drag, drop code created for it. Works fine in FF, even IE but not in Safari or Chrome. Below is the jquery code in load_products.php that gets created when the ajax call is made to load the products. http://tandyleatherfactory.net/ Anyone have any idea why wouldn't work in Safari? $(function() {$("#concho_4_2").draggable({ helper: 'clone', cursor: 'pointer', zIndex: '1001', stop: function(event, ui) { offsetElement = $(ui.helper).offset(); offNewContainer = $('#belts').offset(); var dataId = $(ui.helper).attr('id'); ajaxRequest('http://tandyleatherfactory.net/includes/ahah/add_product.php', 'product=4', '#conchos'); var randomnumber = Math.floor(Math.random()*1000000); var newId = 'concho_4_2_'+randomnumber; $(ui.helper).clone(true).removeAttr('id').attr('id',newId).css("left", offsetElement.left-offNewContainer.left-10).css("top", offsetElement.top-offNewContainer.top-10).appendTo('#belts'); $('#'+newId).draggable(); } });

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• Better way to summarize data about stop times?

  - by Vimvq1987

  This question is close to this: http://stackoverflow.com/questions/2947963/find-the-period-of-over-speed Here's my table: Longtitude Latitude Velocity Time 102 401 40 2010-06-01 10:22:34.000 103 403 50 2010-06-01 10:40:00.000 104 405 0 2010-06-01 11:00:03.000 104 405 0 2010-06-01 11:10:05.000 105 406 35 2010-06-01 11:15:30.000 106 403 60 2010-06-01 11:20:00.000 108 404 70 2010-06-01 11:30:05.000 109 405 0 2010-06-01 11:35:00.000 109 405 0 2010-06-01 11:40:00.000 105 407 40 2010-06-01 11:50:00.000 104 406 30 2010-06-01 12:00:00.000 101 409 50 2010-06-01 12:05:30.000 104 405 0 2010-06-01 11:05:30.000 I want to summarize times when vehicle had stopped (velocity = 0), include: it had stopped since "when" to "when" in how much minutes, how many times it stopped and how much time it stopped. I wrote this query to do it: select longtitude, latitude, MIN(time), MAX(time), DATEDIFF(minute, MIN(Time), MAX(time)) as Timespan from table_1 where velocity = 0 group by longtitude,latitude select DATEDIFF(minute, MIN(Time), MAX(time)) as minute into #temp3 from table_1 where velocity = 0 group by longtitude,latitude select COUNT(*) as [number]from #temp select SUM(minute) as [totaltime] from #temp3 drop table #temp This query return: longtitude latitude (No column name) (No column name) Timespan 104 405 2010-06-01 11:00:03.000 2010-06-01 11:10:05.000 10 109 405 2010-06-01 11:35:00.000 2010-06-01 11:40:00.000 5 number 2 totaltime 15 You can see, it works fine, but I really don't like the #temp table. Is there anyway to query this without use a temp table? Thank you.

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• How To Go About Updating Old C Code

  - by Ben313

  Hello: I have been working on some 10 year old C code at my job this week, and after implementing a few changes, I went to the boss and asked if he needed anything else done. Thats when he dropped the bomb. My next task was to go through the 7000 or so lines and understand more of the code, AND, to modularize the code somewhat. I asked him how he would like the source code modularized, and he said to start putting the old C code into c++ classes. Being a good worker, I nodded my head yes, and went back to my desk, where I sit now, wondering how in the world to take this code, and "modularize" it. Its already in 20 source files, each with its own purpose and function. in addition, there are three "main" structs. each of these stuctures has 30 plus fields, many of them being other, smaller sturcts. Its a complete mess to try to understand, but almost every single function in the program is passed a pointer to one of the structs, and uses the struct heavily. Is there any clean way for me to shoehorn this into classes? I am resolved to do it if it can be done, I just have no idea how to begin.

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• Delphi Pascal / Windows API - Small problem with SetFilePointerEx and parameter FILE_END

  - by SuicideClutchX2

  I know I am about to be slapped by at least one person who was helping me with this API. Alright I have been able to use SetFilePointerEx just fine, when setting the position only. SetFilePointerEx(PD,512,@PositionVar,FILE_BEGIN); SetFilePointerEx(PD,0,@PositionVar,FILE_CURRENT); Both work, I can set positions and even check my current one. But when I set FILE_END as per the documentation no matter what the second parameter is and whether or not i provide a pointer for the third parameter it fails even on a valid handle that many other operations are able to use without fail. For Example: SetFailed := SetFilePointerEx(PD,0,@PositionVar,FILE_END); SetFailed := SetFilePointerEx(PD,0,nil,FILE_END); Whatever I put it fails. I am working with a handle to a physical disk and it most definitely has an end. SetFilePointer works just fine its just a little more trouble than I would like. Its not the end of the world, but whats happening.

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• Creating a json array and json items with jquery?

  - by user246114

  Hi, I made a simple javascript class like this: function Horse() { this.color = 'brown'; this.speed = 'somewhat slow'; } I attached a few instances to some elements, like this: $("#horse1").data('d', new Horse()); $("#horse2").data('d', new Horse()); $("#horse3").data('d', new Horse()); now I want to create a JSON array with a JSON representation of each horse object. So I'm doing this: // How do I create an empty JSON array here?: var myJsonArray = ?; var children = $("#horses").children(); for (var i = 0, m = children.size(); i < m; i++) { var panel = children[i]; var horse = $(panel).data('h'); // And how do I create a JSON rep of my horse here? var myJsonHorse = new JsonHorse(?); // Finally, how do I add it to the json array? myJsonArray.push(myJsonHorse); } yeah my end goal is to have a single json array of all the horses after iterating over all the children - not sure if this should be done in plain javascript or in jquery? Thanks

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• Really strange problem with jailbroken iPhone 4. Lags but fixes by running Cydia a second

  - by Charkel

  I have jailbreaked my iPhone 4 iOS 4.1 with both limera1n and greenpois0n and the outcome is the same. My phone is really slow opening apps. (including Phone.app an SMS.app) they take about 10-15seconds to load. BUT if I start Cydia for only one second everything goes back to normal. (Please note that I have to have 3G or WI-FI access to do this) Until I let my phone sit for about 15 minutes then it's the same again. Please note that if I don't exit the apps they seem to continue working but with a bit of lag. Cydia also seems to be the only app not affected by the delay. "Loding Data" appears as quick as normal. These issues did not start to appear until about 2 weeks after I jailbreaked my phone. I have tried running "speed test" while it's in its slow state. I start the app and the app loads for like 15 seconds and then the result shows everyhting is good. All green. Since Cydia seems for fix it temporarily i figured it's jailbreak-related and not hardware-related.

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• Effective Method to Manage and Search Through 100,000+ Objects Instantly? (C#)

  - by Kirk

  I'm writing a media player for enthusiasts with large collections (over 100,000 tracks) and one of my main goals is speed in search. I would like to allow the user to perform a Google-esque search of their entire music collection based on these factors: Song Path and File Name Items in ID3 Tag (Title, Artist, Album, etc.) Lyrics What is the best way for me to store this data and search through it? Currently I am storing each track in an object and iterating over an array of these objects checking each of their variables for string matches based on given search text. I've run into problems though where my search is not effective because it is always a phrase search and I'm not sure how to make it more fuzzy. Would an internal DB like SQLlite be faster than this? Any ideas on how I should structure this system? I also need playlist persistence, so that when they close the app and open the app their same playlist loads immediately. How should I store the playlist information so it can load quickly when the application starts? Currently I am JSON encoding the entire playlist, storing it in a text file, and reading it into the ListView at runtime, but it is getting sluggish over 20,000 tracks. Thanks!

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• how to handle onclick event of button inside popup window in android

  - by henna

  In my application i have a button initially on the screen and in onclick of the button ,popup window should open. In the popup window i have an imagebutton , now on click of this button i want to start an activity. The popup window opens but i dont understand how to handle the onclick of the imagebtn inside popup window. In main.xml i have a button and in popup_example.xml i have an imagebutton. Hi my Java code is as follows: final LayoutInflater inflater = (LayoutInflater)this.getSystemService(Context.LAYOUT_INFLATER_SERVICE); final Button b=(Button)findViewById(R.id.btn); b.setOnClickListener(new OnClickListener() { public void onClick(View v) { PopupWindow pw = new PopupWindow(inflater.inflate(R.layout.popup_example,(ViewGroup)findViewById(R.layout.main))); pw.showAtLocation(v, Gravity.LEFT,0,0); pw.update(8,-70,150,270); //if onclick written here, it gives null pointer exception. ImageButton img=(ImageButton)findViewById(R.id.home); img.setOnClickListener(new OnClickListener() { public void onClick(View v) { Intent..... } }); //if onclick is written here it gives runtime exception. }); and i have two xml layouts.........1)main.xml 2)popup_example.xml main.xml popup_example.xml <ImageButton android:id="@+id/home" android:layout_width="wrap_content" android:layout_height="wrap_content" android:focusable="true" android:src="@drawable/vitalss" android:layout_weight="1" android:background="#8E2323" />

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• Using memcache together with conventional cache

  - by Industrial

  Hi! Here's the deal. We would have taken the complete static html road to solve performance issues, but since the site will be partially dynamic, this won't work out for us. What we have thought of instead is using memcache + eAccelerator to speed up PHP and take care of caching for the most used data. Here's our two approaches that we have thought of right now: Using memcache on all<< major queries and leaving it alone to do what it does best. Usinc memcache for most commonly retrieved data, and combining with a standard harddrive-stored cache for further usage. The major advantage of only using memcache is of course the performance, but as users increases, the memory usage gets heavy. Combining the two sounds like a more natural approach to us, even though the theoretical compromize in performance. Memcached appears to have some replication features available as well, which may come handy when it's time to increase the nodes. What approach should we use? - Is it stupid to compromize and combine the two methods? Should we insted be focusing on utilizing memcache and instead focusing on upgrading the memory as the load increases with the number of users? Thanks a lot!

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• UISlider won't display

  - by user290295

  I have been having a lot of difficulty adding custom track images to a UISlider. Whenever I do this, whether to a nib created UISlider or a hand programmed UISlider the slider refuses to display. Also, I even commented the track image code out below and the UISlider still refuses to display. There are other nib created sliders in the controlView that display and function fine. if (![self loadView:keyboardControlView intoSuperview:controlView withNib:@"KeyboardControl"]) { NSLog(@"Could not load controlView from nib into synthControlView"); } // nibSlider is an outlet to a UISlider in the above loaded nib file CGRect sliderFrame = nibSlider.frame; float sliderMinimum = nibSlider.minimumValue; float sliderMaximum = nibSlider.maximumValue; float sliderValue = nibSlider.value; // remove from superview, implicitly releasing UISlider [nibSlider removeFromSuperview]; // reuse pointer to allocate new UISlider using rect obtained from nib nibSlider = [[UISlider alloc] initWithFrame:sliderFrame]; nibSlider.backgroundColor = [UIColor clearColor]; nibSlider.minimumValue = sliderMinimum; nibSlider.maximumValue = sliderMaximum; nibSlider.continuous = YES; nibSlider.value = sliderValue; //[nibSlider setMinimumTrackImage:[[UIImage imageNamed:@"violetslider.png"] //stretchableImageWithLeftCapWidth:5.0 topCapHeight:0.0] forState:UIControlStateNormal]; // //[nibSlider setMaximumTrackImage:[[UIImage imageNamed:@"violetslider.png"] // stretchableImageWithLeftCapWidth:5.0 topCapHeight:0.0] forState:UIControlStateNormal]; [nibSlider addTarget:delegate action:@selector(sliderUpdate:) forControlEvents:UIControlEventValueChanged]; [controlView addSubview:nibSlider]; // do not release here as slider will need to remain cached. push onto a release stack. [nibSlider setNeedsDisplay];

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• How do I get jQuery's Uploadify plugin to work with ASP.NET MVC?

  - by KingNestor

  I'm in the process of trying to get the jQuery plugin, Uploadify, to work with ASP.NET MVC. I've got the plugin showing up fine: With the following javascript snippet: <script type="text/javascript"> $(document).ready(function() { $('#fileUpload').fileUpload({ 'uploader': '/Content/Flash/uploader.swf', 'script': '/Placement/Upload', 'folder': '/uploads', 'multi': 'true', 'buttonText': 'Browse', 'displayData': 'speed', 'simUploadLimit': 2, 'cancelImg': '/Content/Images/cancel.png' }); }); </script> Which seems like all is well in good. If you notice, the "script" attribute is set to my /Placement/Upload, which is my Placement Controller and my Upload Action. The main problem is, I'm having difficulty getting this action to fire to receive the file. I've set a breakpoint on that action and when I select a file to upload, it isn't getting executed. I've tried changing the method signature based off this article: public string Upload(HttpPostedFileBase FileData) { /* * * Do something with the FileData * */ return "Upload OK!"; } But this still doesn't fire. Can anyone help me write and get the Upload controller action's signature correctly so it will actually fire? I can then handle dealing with the file data myself. I just need some help getting the method action to fire.

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• Implementation/interface inheritance design question.

  - by Neil G

  I would like to get the stackoverflow community's opinion on the following three design patterns. The first is implementation inheritance; the second is interface inheritance; the third is a middle ground. My specific question is: Which is best? implementation inheritance: class Base { X x() const = 0; void UpdateX(A a) { y_ = g(a); } Y y_; } class Derived: Base { X x() const { return f(y_); } } interface inheritance: class Base { X x() const = 0; void UpdateX(A a) = 0; } class Derived: Base { X x() const { return x_; } void UpdateX(A a) { x_ = f(g(a)); } X x_; } middle ground: class Base { X x() const { return x_; } void UpdateX(A a) = 0; X x_; } class Derived: Base { void UpdateX(A a) { x_ = f(g(a)); } } I know that many people prefer interface inheritance to implementation inheritance. However, the advantage of the latter is that with a pointer to Base, x() can be inlined and the address of x_ can be statically calculated.

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• What is a good automated data import method for SQL Server?

  - by Joel Potter

  I'm in the process of porting some SQL Server 2005 databases to SQL Server 2008. One of these databases has an associated import application (Windows task) which uses SSIS with a DTS package to import a large dataset from an MS Access database nightly. In upgrading to SQL Server 2008, I discovered that I can't run the same console application which has been performing the imports due to the missing manageddts DLL in SQL Server 2008. It's several years old and in need of a rewrite for various reason, plus, I've been fairly unhappy with DTS in general. The original reason DTS was chosen was for speed (5 min import time compared to 30+ for ADO.NET). The format of the data to import is out of my control (the client likes Access). I would also like to be able to run the import from a machine completely separate from the server hosting SQL Server and preferably with minimal SQL features installed. Options I've considered: Creating an Access application to connect to both databases (SQL Server and Access) and perform the import (Ugh!) Revisiting ADO.NET to see if the original implementation was poorly written. Updated SSIS packages. What other technologies should I be considering for this job?

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• How do I mock a method with an open array parameter in PascalMock?

  - by Oliver Giesen

  I'm currently in the process of getting started with unit testing and mocking for good and I stumbled over the following method that I can't seem to fabricate a working mock implementation for: function GetInstance(const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID = CID_DEFAULT): Boolean; (TImplContextID is just an alias for Integer) I thought it would have to look something like this: function TImplementationProviderMock.GetInstance( const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID): Boolean; begin Result := AddCall('GetInstance') .WithParams([@AIID, AContextID]) .ReturnsOutParams([AInstance]) .ReturnValue; end; But the compiler complains about the .ReturnsOutParams([AInstance]) saying "Bad argument type in variable type array constructor.". Also I haven't found a way to specify the open array parameter AArgs at all. Also, is using the @-notation for the TGUID-typed parameter the right way to go? Is it possible to mock this method with the current version of PascalMock at all? Update: I now realize I got the purpose of ReturnsOutParams completely wrong: It's intended to be used for populating the values to be returned when defining the expectations rather than for mocking the call itself. I now think the correct syntax for mocking the out parameter would probably have to look more like this: function TImplementationProviderMock.GetInstance( const AIID: TGUID; out AInstance; const AArgs: array of const; const AContextID: TImplContextID): Boolean; var lCall: TMockMethod; begin lCall := AddCall('GetInstance').WithParams([@AIID, AContextID]); Pointer(AInstance) := lCall.OutParams[0]; Result := lCall.ReturnValue; end; The questions that remain are how to mock the open array parameter AArgs and whether passing the TGUID argument (i.e. a value type) by address will work out...

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• Audio output from Silverlight

  - by leecarter

  I'm looking to develop a Silverlight application which will take a stream of data (not an audio stream as such) from a web server. The data stream would then be manipulated to give audio of a certain format (G.711 a-Law for example) which would then be converted into PCM so that additional effects can be applied (such as boosting the volume). I'm OK up to this point. I've got my data, converted the G.711 into PCM but my problem is being able to output this PCM audio to the sound card. I basing a solution on some C# code intended for a .Net application but in Silverlight there is a problem with trying to take a copy of a delegate (function pointer) which will be the topic of a separate question once I've produced a simple code sample. So, the question is... How can I output the PCM audio that I have held in a data structure (currently an array) in my Silverlight to the user? (Please don't say write the byte values to a text box) If it were a MP3 or WMA file I would play it using a MediaElement but I don't want to have to make it into a file as this would put a crimp on applying dynamic effects to the audio. I've seen a few posts from people saying low level audio support is poor/non-existant in Silverlight so I'm open to any suggestions/ideas people may have.

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• Mulit-dimensional array edge/border conditions

  - by kirbuchi

  Hi, I'm iterating over a 3 dimensional array (which is an image with 3 values for each pixel) to apply a 3x3 filter to each pixel as follows: //For each value on the image for (i=0;i<3*width*height;i++){ //For each filter value for (j=0;j<9;j++){ if (notOutsideEdgesCondition){ *(**(outArray)+i)+= *(**(pixelArray)+i-1+(j%3)) * (*(filter+j)); } } } I'm using pointer arithmetic because if I used array notation I'd have 4 loops and I'm trying to have the least possible number of loops. My problem is my notOutsideEdgesCondition is getting quite out of hands because I have to consider 8 border cases. I have the following handled conditions Left Column: ((i%width)==0) && (j%3==0) Right Column: ((i-1)%width ==0) && (i>1) && (j%3==2) Upper Row: (i<width) && (j<2) Lower Row: (i>(width*height-width)) && (j>5) and still have to consider the 4 corner cases which will have longer expressions. At this point I've stopped and asked myself if this is the best way to go because If I have a 5 line long conditional evaluation it'll not only be truly painful to debug but will slow the inner loop. That's why I come to you to ask if there's a known algorithm to handle this cases or if there's a better approach for my problem. Thanks a lot.

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• std::string insert method has ambiguous overloads?

  - by sdg

  Environment: VS2005 C++ using STLPort 5.1.4. Compiling the following code snippet: std::string copied = "asdf"; char ch = 's'; copied.insert(0,1,ch); I receive an error: Error 1 error C2668: 'stlpx_std::basic_string<_CharT,_Traits,_Alloc>::insert' : ambiguous call to overloaded function It appears that the problem is the insert method call on the string object. The two defined overloads are void insert ( iterator p, size_t n, char c ); string& insert ( size_t pos1, size_t n, char c ); But given that STLPort uses a simple char* as its iterator, the literal zero in the insert method in my code is ambiguous. So while I can easily overcome the problem by hinting such as copied.insert(size_t(0),1,ch); My question is: is this overloading and possible ambiguity intentional in the specification? Or more likely an unintended side-effect of the specific STLPort implementation? (Note that the Microsoft-supplied STL does not have this problem as it has a class for the iterator, instead of a naked pointer)

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• PHP Socket Server vs node.js: Web Chat

  - by Eliasdx

  I want to program a HTTP WebChat using long-held HTTP requests (Comet), ajax and websockets (depending on the browser used). Userdatabase is in mysql. Chat is written in PHP except maybe the chat stream itself which could also be written in javascript (node.js): I don't want to start a php process per user as there is no good way to send the chat messages between these php childs. So I thought about writing an own socket server in either PHP or node.js which should be able to handle more then 1000 connections (chat users). As a purely web developer (php) I'm not much familiar with sockets as I usually let web server care about connections. The chat messages won't be saved on disk nor in mysql but in RAM as an array or object for best speed. As far as I know there is no way to handle multiple connections at the same time in a single php process (socket server), however you can accept a great amount of socket connections and process them successive in a loop (read and write; incoming message - write to all socket connections). The problem is that there will most-likely be a lag with ~1000 users and mysql operations could slow the whole thing down which will then affect all users. My question is: Can node.js handle a socket server with better performance? Node.js is event-based but I'm not sure if it can process multiple events at the same time (wouldn't that need multi-threading?) or if there is just an event queue. With an event queue it would be just like php: process user after user. I could also spawn a php process per chat room (much less users) but afaik there are singlethreaded IRC servers which are also capable to handle thousands of users. (written in c++ or whatever) so maybe it's also possible in php. I would prefer PHP over Node.js because then the project would be php-only and not a mixture of programming languages. However if Node can process connections simultaneously I'd probably choose it.

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• Fastest Java way to remove the first/top line of a file (like a stack)

  - by christangrant

  I am trying to improve an external sort implementation in java. I have a bunch of BufferedReader objects open for temporary files. I repeatedly remove the top line from each of these files. This pushes the limits of the Java's Heap. I would like a more scalable method of doing this without loosing speed because of a bunch of constructor calls. One solution is to only open files when they are needed, then read the first line and then delete it. But I am afraid that this will be significantly slower. So using Java libraries what is the most efficient method of doing this. --Edit-- For external sort, the usual method is to break a large file up into several chunk files. Sort each of the chunks. And then treat the sorted files like buffers, pop the top item from each file, the smallest of all those is the global minimum. Then continue until for all items. http://en.wikipedia.org/wiki/External_sorting My temporary files (buffers) are basically BufferedReader objects. The operations performed on these files are the same as stack/queue operations (peek and pop, no push needed). I am trying to make these peek and pop operations more efficient. This is because using many BufferedReader objects takes up too much space.

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• How to scale JPEG images with a non-standard sampling factor in Java?

  - by HRJ

  I am using Java AWT for scaling a JPEG image, to create thumbnails. The code works fine when the image has a normal sampling factor ( 2x2,1x1,1x1 ) However, an image which has this sampling factor ( 1x1, 1x1, 1x1 ) creates problem when scaled. The colors get corrupted though the features are recognizable. The original and the thumbnail: The code I am using is roughly equivalent to: static BufferedImage awtScaleImage(BufferedImage image, int maxSize, int hint) { // We use AWT Image scaling because it has far superior quality // compared to JAI scaling. It also performs better (speed)! System.out.println("AWT Scaling image to: " + maxSize); int w = image.getWidth(); int h = image.getHeight(); float scaleFactor = 1.0f; if (w > h) scaleFactor = ((float) maxSize / (float) w); else scaleFactor = ((float) maxSize / (float) h); w = (int)(w * scaleFactor); h = (int)(h * scaleFactor); // since this code can run both headless and in a graphics context // we will just create a standard rgb image here and take the // performance hit in a non-compatible image format if any Image i = image.getScaledInstance(w, h, hint); image = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB); Graphics2D g = image.createGraphics(); g.drawImage(i, null, null); g.dispose(); i.flush(); return image; } (Code courtesy of this page ) Is there a better way to do this? Here's a test image with sampling factor of [ 1x1, 1x1, 1x1 ].

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• How to use setTimeout / .delay() to wait for typing between characters

  - by Darcy

  Hi all, I am creating a simple listbox filter that takes the user input and returns the matching results in a listbox via javascript/jquery (roughly 5000+ items in listbox). Here is the code snippet: var Listbox1 = $('#Listbox1'); var commands = document.getElementById('DatabaseCommandsHidden'); //using js for speed $('#CommandsFilter').bind('keyup', function() { Listbox1.children().remove(); for (var i = 0; i < commands.options.length; i++) { if (commands.options[i].text.toLowerCase().match($(this).val().toLowerCase())) { Listbox1.append($('<option></option>').val(i).html(commands.options[i].text)); } } }); This works pretty well, but slows down somewhat when the 1st/2nd char's are being typed since there are so many items. I thought a solution I could use would be to add a delay to the textbox that prevents the 'keyup' event from being called until the user stops typing. The problem is, I'm not sure how to do that, or if its even a good idea or not. Any suggestions/help is greatly appreciated.

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