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  • Scalability 101: How can I design a scalable web application using PHP?

    - by Legend
    I am building a web-application and have a couple of quick questions. From what I learnt, one should not worry about scalability when initially building the app and should only start worrying when the traffic increases. However, this being my first web-application, I am not quite sure if I should take an approach where I design things in an ad-hoc manner and later "fix" them. I have been reading stories about how people start off with an app that gets millions of users in a week or two. Not that I will face the same situation but I can't help but wonder, how do these people do it? Currently, I bought a shared hosting account on Lunarpages and that got me started in building and testing the application. However, I am interested in learning how to build the same application in a scalable-manner using the cloud, for instance, Amazon's EC2. From my understanding, I can see a couple of components: There is a load balancer that first receives requests and then decides where to route each request This request is then handled by a server replica that then processes the request and updates (if required) the database and sends back the response to the client If a similar request comes in, then a caching mechanism like memcached kicks into picture and returns objects from the cache A blackbox that handles database replication Specifically, I am trying to do the following: Setting up a load balancer (my homework revealed that HAProxy is one such load balancer) Setting up replication so that databases can be synchronized Using memcached Configuring Apache to work with multiple web servers Partitioning application to use Amazon EC2 and Amazon S3 (my application is something that will need great deal of storage) Finally, how can I avoid burning myself when using Amazon services? Because this is just a learning phase, I can probably do with 2-3 servers with a simple load balancer and replication but until I want to avoid paying loads of money accidentally. I am able to find resources on individual topics but am unable to find something that starts off from the big picture. Can someone please help me get started?

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  • Magento products will not show in category

    - by Aaron
    I've recently been tasked with the build and deployment of a large Ecommerce site. In the past we've had to use the clients legacy X-cart installation for redevelopment (too far integrated with their existing work flow). We'd heard good things about Magento, so I've set up a test install to get to grips with it. After a couple of initial issues, there is a live development site which displays categories on the default theme. The problem we've hit now is that products don't display..! After a lot more in-depth research into this, all I've been able to discover is that quite a number of developers endorse using other solutions entirely, with the other 50% saying after the steep learning curve the platform is as wonderful as we'd initially been led to believe. Now, my test category is showing, so I know this is configured properly. I've set up three test products and associated them with this (all done following the Magento user guide), checked double checked and thrice checked the products are enabled and visible individually, yet still the front end says the category has no products in it. I've cleared the cache repeatedly, reset everything possible many times in index management - no products show up. I have to make a call tomorrow morning on whether we're going ahead with Magento. If I can't even get it to show products I'm going to have to go with something with a more established track record and more community support available. Can anybody advise what could possibly be wrong here?

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  • Random syntactical error in my php code that I can't find

    - by user348538
    Ordinarily I hate coming here with newbie code questions but nobody can find the error with this code. Maybe you guys can :-) <?php defined('SYSPATH') or die('No direct script access.'); /** * to interact with photos * * @author Max Padraig Wolfgang Bucknell-Leahy */ class Model_Photos { private $apiKey = '12664498208a1380fe49fb1b5a238ef0'; private $secret = '03d43dee65a34513'; private $perms = 'read'; private $sigString = 'test'; private $apiSig = md5($_sigString); private $authArray = array('api_key' => $apiKey, 'perms' => $perms, 'api_sig' => $apiSig); private $authArrayImploded = implode('&', $authArray); private $authLink = 'http://www.flickr.com/services/auth/?' . $authArrayImploded; public function get_photos($number = 5) { if(file_exists(APPPATH . 'cache/main_cache.xml') { echo $authLink; } else { echo 'not so good'; /** */ } } } $class = new Model_Photos; $class->get_photos; the error is: Parse error: syntax error, unexpected '(', expecting ',' or ';' in /home/p14s9nnd/public_html/testing.php on line 15 Thank you in advance and sorry Regards, Max

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  • byte + byte = int... why?

    - by Robert C. Cartaino
    Looking at this C# code... byte x = 1; byte y = 2; byte z = x + y; // ERROR: Cannot implicitly convert type 'int' to 'byte' The result of any math performed on byte (or short) types is implicitly cast back to an integer. The solution is to explicitly cast the result back to a byte, so... byte z = (byte)(x + y); // works What I am wondering is why? Is it architectural? Philosophical? We have: int + int = int long + long = long float + float = float double + double = double So why not: byte + byte = byte short + short = short ? A bit of background: I am performing a long list of calculations on "small numbers" (i.e. < 8) and storing the intermediate results in a large array. Using a byte array (instead of an int array) is faster (because of cache hits). But the extensive byte-casts spread through the code make it that much more unreadable.

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  • SQLite DB open time really long Problem

    - by sxingfeng
    I am using sqlite in c++ windows, And I have a db size about 60M, When I open the sqlite db, It takes about 13 second. sqlite3* mpDB; nRet = sqlite3_open16(szFile, &mpDB); And if I closed my application and reopen it again. It takse only less then 1 second. First, I thought It is because of disk cache. So I preload the 60M db file before sqlite open, and read the file using CFile, However, after preloading, the first time is still very slow. BOOL CQFilePro::PreLoad(const CString& strPath) { boost::shared_array<BYTE> temp = boost::shared_array<BYTE>(new BYTE[PRE_LOAD_BUFFER_LENGTH]); int nReadLength; try { CFile file; if (file.Open(strPath, CFile::modeRead) == FALSE) { return FALSE; } do { nReadLength = file.Read(temp.get(), PRE_LOAD_BUFFER_LENGTH); } while (nReadLength == PRE_LOAD_BUFFER_LENGTH); file.Close(); } catch(...) { } return TRUE; } My question is what is the difference between first open and second open. How can I accelerate the sqlite open-process.

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  • Ruby on Rails: Uploading a modifed site.

    - by Califer
    I'm having a heck of a time getting a site I modified to work correctly. I didn't set the site up originally, and since the person that set it up no longer works with me I had to learn ruby just to make some changes. I made all the changes in the development server and everything worked fine. Then I did a diff on the production and development and moved only my changes over. Unfortunately when I loaded my changes onto the production server I got a lot of errors. I've changed all of the permissions to 755, which took care being able to access anything at all, but after that I started getting a lot of 500 errors. Nothing showed up in the production.log file. I really have no clue what's going wrong except that perhaps things are not noticing the new changes. I moved the old site to a backup folder, and the new site crashes whenever it goes to anything that I've changed. In particular, I added a link to a new setup with an extra controller/model/view group. It works fine on development but in production it gives me a 404. Yes, I did copy all the files up. I even put everything back how it was, but the website is still showing the broken version of it. I checked the tmp/cache folder but it was empty. Running dispatch.fcgi shows the old site (which I expected) but it still shows the flawed new site when I connect through a browser. I've been tearing my hair out trying to get this to work. Any ideas as to how I can get this to work?

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  • Named pipe stalls threads?

    - by entens
    I am attempting to push updates into a process via a named pipe, but in doing so my process loop now seams to stall on while ((line = sr.ReadLine()) != null). I'm a little mystified as to what might be wrong as this is my first foray into named pipes. void RefreshThread() { using (NamedPipeServerStream pipeStream = new NamedPipeServerStream("processPipe", PipeDirection.In)) { pipeStream.WaitForConnection(); using (StreamReader sr = new StreamReader(pipeStream)) { for (; ; ) { if (StopThread == true) { StopThread = false; return; // exit loop and terminate the thread } // push update for heartbeat int HeartbeatHandle = ItemDictionary["Info.Heartbeat"]; int HeartbeatValue = (int)Config.Items[HeartbeatHandle].Value; Config.Items[HeartbeatHandle].Value = ++HeartbeatValue; SetItemValue(HeartbeatHandle, HeartbeatValue, (short)0xC0, DateTime.Now); string line = null; while ((line = sr.ReadLine()) != null) { // line is in the format: item, value, timestamp string[] parts = line.Split(','); // push update and store value in item cache int handle = ItemDictionary[parts[0]]; object value = parts[1]; Config.Items[handle].Value = int.Parse(value); DateTime timestamp = DateTime.FromBinary(long.Parse(parts[2])); SetItemValue(handle, value, (short)0xC0, timestamp); } Thread.Sleep(500); } } } }

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  • Jquery Ajax Search on pressing return key in Internet Explorer

    - by haribo83
    Hi I have found the following code to create a search on my site - this works really well the only problem is in Internet Explorer the search doesn't work when you press the return key. Does anybody have any ideas? The search code is below - if anything else is needed please let me know. $(function() { $(".search_button").click(function() { var search_word = $("#search_box").val(); var dataString = 'search_word='+ search_word; if(search_word=='') { } else { $.ajax({ type: "GET", url: "searchdata.php", data: dataString, cache: false, beforeSend: function(html) { document.getElementById("insert_search").innerHTML = ''; $("#flash").show(); $("#searchword").show(); $(".searchword").html(search_word); $("#flash").html('<img src="ajax-loader.gif" /> Loading Results...'); }, success: function(html){ $("#insert_search").show(); $("#insert_search").append(html); $("#flash").hide(); } }); } return false; }); });

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  • VS2008 Link Error Using SafeInt3.hpp in 64bit mode.

    - by photo_tom
    I have the below code that links and runs fine in 32bit mode - #include "safeint3.hpp" typedef SafeInt<SIZE_T> SAFE_SIZE_T; SAFE_SIZE_T sizeOfCache; SAFE_SIZE_T _allocateAmt; Where safeint3.hpp is current version that can be found on Codeplex SafeInt. For those who are unaware of it, safeint is a template class that makes working with different integer types and sizes "safe". To quote channel 9 video on software - "it writes the code that you should". Which is my case. I have a class that is managing a large in-memory cache of objects (6gb) and I am very concerned about making sure that I don't have overflow/underflow issues on my pointers/sizes/other integer variables. In this use, it solves many problems. My problem is coming when moving from 32bit dev mode to 64bit production mode. When I build the app in this mode, I'm getting the following linker warnings - 1>cachecontrol.obj : warning LNK4006: "bool __cdecl IntrinsicMultiplyUint64(unsigned __int64 const &,unsigned __int64 const &,unsigned __int64 *)" (?IntrinsicMultiplyUint64@@YA_NAEB_K0PEA_K@Z) already defined in ImageInRamCache.obj; second definition ignored 1>cachecontrol.obj : warning LNK4006: "bool __cdecl IntrinsicMultiplyInt64(__int64 const &,__int64 const &,__int64 *)" (?IntrinsicMultiplyInt64@@YA_NAEB_J0PEA_J@Z) already defined in ImageInRamCache.obj; second definition ignored While I understand I can ignore the error, I would like either (a) prevent the warning from occurring or (b) make it disappear so that my QA department doesn't flag it as a problem. And after spending some time researching it, I cannot find a way to do either.

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  • MySQL + Joomla + remote c# access

    - by Jimmy
    Hello, I work on a Joomla web site, installed on a MySQL database and running on IIS7. It's all working fine. I now need to add functionality that lets (Joomla-)registered users change some configuration data. Though I haven't done this yet, it looks straightforward enough to do with Joomla. The data is private so all external access will be done through HTTPS. I also need an existing c# program, running on another machine, to read that configuration data. Sure enough, this data access needs to be as fast as possible. The data will be small (and filtered by query), but the latency should be kept to a minimum. A short-term, client-side cache (less than a minute, in case a user updates his configuration data) seems like a good idea. I have done practically zero database/asp programming so far, so what's the best way of doing that last step? Should the c# program access the database 'directly' (using what? LINQ?) or setup some sort of Facade (SOAP?) service? If a service should be used, should it be done through Joomla or with ASP on IIS? Thanks

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  • Ensure that my C# desktop application is making requests to my ASP .NET MVC action?

    - by Mathias Lykkegaard Lorenzen
    I've seen questions that are almost identical to this one, except minor but important differences that I would like to get detailed. Let's say that I have a controller and an action method in MVC which therefore accepts requests on the following URL: http://example.com/api/myapimethod?data=some-data-here. This URL is then being called regularly by 1000 clients or more spread out in the public. The reason for this is crowdsourcing. The clients around the globe help feed a global cache on my server, which makes it faster for the rest of the clients to fetch the data. Now, if I'm sneaky (and I am), I can go into Fiddler, Ethereal, Wireshark or any other packet sniffing tool and figure out which requests the program is making. By figuring that out, I can also replicate them, and fill the service with false corrupted data. What is the best approach to ensuring that the data received in my ASP .NET MVC action method is actually from the desktop client application, and not some falsely generated data that the user invented? Since it is all based on crowdsourcing, would it be a good idea for my users to be able to "vote" if some data is falsified, and then let an automatic cleanup commence if there are enough votes? I do not have access to a tool like SmartAssembly, so unfortunately my .NET program is fully decompilable. I realize this might be impossible to accomplish in an error-proof manner, but I would like to know where my best chances are.

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  • auto refresh of div in mvc3 ASP.Net not working

    - by user1493249
    ViewData.cshtml(Partial View) Date Bill Amount PayNow </tr> </thead> <tbody> @{ for (int i = @Model.bill.Count - 1; i >= 0; i--) { <tr> <td width="30%" align="center">@Model.billdate[i]</td> <td width="30%" align="center">@Model.bill[i]</td> <td width="30%" align="center"> <a class="isDone" href="#" data-tododb-itemid="@Model.bill[i]">Paynow</a> </td> </tr> } } </tbody> Index.cshtml(View) $(document).ready(function () { window.setInterval(function () { var url = '@Url.Action("SomeScreen", "Home")'; $('#dynamictabs').load(url) }, 9000); $.ajaxSetup({ cache: false }); }); @Html.Partial("ViewData") HomeController.cs(Controller) public ActionResult Index() { fieldProcessor fp= new fieldProcessor(); return View(fp); } public ActionResult ShowScreen() { return View("ViewData",fp); } Still the same is not working..

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  • Implementing Tagging System with PHP and mySQL. Caching help!!!

    - by Hamid Sarfraz
    With reference to this post: http://stackoverflow.com/questions/2122546/how-to-implement-tag-counting I have implemented the suggested 3 table tagging system completely. To count the number of Articles per tag, i am using another column named tagArticleCount in the tag definition table. (other columns are tagId, tagText, tagUrl, tagArticleCount). If i implement realtime editing of this table, so that whenever user adds another tag to article or deletes an existing tag, the tag_definition_table is updated to update the counter of the added/removed tag. This will cost an extra query each time any modification is made. (at the same time, related link entry for tag and article is deleted from tagLinkTable). An alternative to this is not allowing any real time editing to the counter, instead use CRONs to update counter of each tag after a specified time period. Here comes the problem that i want to discuss. This can be seen as caching the article count in database. Can you please help me find a way to present the articles in a list when a tag is explored and when the article counter for that tag is not up to date. For example: 1. Counter shows 50 articles, but there are infact 55 entries in the tag link table (that links tags and articles). 2. Counter shows 50 articles, but there are infact 45 extries in the tag link table. How to handle these 2 scenerios given in example. I am going to use APC to keep cache of these counters. Consider it too in your solution. Also discuss performance in the realtime / CRONNED counter updates.

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  • What are CDN Best Practices?

    - by Wild Thing
    Hi, I have recently started using the Rackspace Cloudfiles CDN (Limelight), about which I have some questions: I am using jQuery, jQuery UI and jQuery tools in addition to custom JS code. Also, my site is written in ASP.Net, which means there is some ASP.Net generated JS code. Right now what I have done is that I have combined all of the js (including the jquery code), except the ASP.Net generated JS into one file. I am hosting this on the Rackspace CDN. I am wondering if it would make more sense to just get the jQuery, jQuery UI files from the Google hosted CDN (which I suspect would work very well in serving these files, since they will be in many users' cache already)? This would mean one extra HTTP request, so I'm not sure if it'll help. Right now I have multiple containers for my assets. For example, in Rackspace I have 3 containers: JS, CSS and Images. The URL subdomain for all 3 is different. Will that lead to a performance penalty? Should I just use one container (and thus one domain for the CDN)? Is there a way of having the MS ASP.Net generated JS loaded from MS CDN? Would this have a performance hit as per the above question? Thanks in advance, WT

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  • Evenly distribute data into columns with JavaScript

    - by marius.cdm
    I'm looking for a way to evenly distribute my JSON data into HTML columns. Using javascript to pull the data $.ajax({ url: "url", dataType: 'json', data: "e="+escape(divID), cache: true, success: function(data) { var items = data; // ??? $('.result').html(list); } }); Input data: ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K"] Expected result: <ul> <li>A</li> <li>B</li> <li>C</li> <li>D</li> </ul> <ul> <li>E</li> <li>F</li> <li>G</li> <li>H</li> </ul> <ul> <li>I</li> <li>J</li> <li>K</li> </ul> I found a partial result here, but the output data is in console. Any help would be appreciated.

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  • How can I allocate 8 GB ( not 1 GB ) RAM to my JDK on windows

    - by Deepak
    JDK on Windows takes max around 2 GB RAM. Even if we allocate more RAM to our JDK; it doesnt take it. If I need to run a process which need 8 GB RAM on Windows; how can I achieve it ? Do we have any JDK provided by any other provider which could support it ? Memcached provides us additional cache which can be used... but that is not I am looking for. Suppose I need to run my jMeter with 8 GB RAM on my windows box; Memcached wont help for sure.. Is there any provider which provides me with this ? Previosly I thought Terracotta does that; but looks like that also is like Memcached. I am using Windows 7. If needed I can use Windows Server also.. I just need to get it running.

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  • Wrong label for a nodereference in Drupal content-type

    - by MPD
    We have a content-type built using CCK. One of the fields is a node reference. The node picker is using a view to build the options. A few days ago, everything was working well. Today, it looks like all node reference fields using views to populate the selection options are displaying the wrong label. Every single label in the option is ``A'', but the actual node number is correct. The form actually works, just the labels are incorrect. We have tried just about every combination of edit/save, disable/enable, reboot, clear cache, clone the view, rebuild the view, new view, etc, but we still have a big list of As. If we create a brand new content type with a brand new node reference field, we get the problem. Through some backup/restore exercises, we have determined that the problem is actually in the database and not in the code. We can restore our last good backup, but we will lose a decent amount of work we have put into other parts of the database. We enabled mysql query logging, and the view is actually being called properly, but we cannot track down where the problem is creeping in after that (unraveling the CCK / Views / Drupal plumbing is a challenge). The install was build with latest stable versions as of April. The problems referred to in http://drupal.org/node/624422 is similar, but our code versions include the patches mentioned. Any ideas would be appreciated. Thanks.

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  • Extremely Difficult Problem with ASP.Net 4.0 WebForms app using Routing

    - by dudeNumber4
    I have a completed app running in a QA environment. Everything works fine under most circumstances. If you hit a plain URL (no identifying information in the URL), you see an intro page with a button (generated by an asp LinkButton control) that posts back and directs you to another page. The markup looks the same when it fails and when it doesn't. When such a URL is followed from, e.g., Word and the default browser is IE, the intro page loads fine, but clicking the button causes an error. When not debugging, this behavior occurs every time. While debugging, the error occurs only ~ 1 in 10 times (closing the browser instance and starting over every time). When the error occurs, the intro page Page_Load fires and IsPostBack is false. Somehow, instead of a post, a get is being issued. When I run fiddler to try to analyze the actual calls (can't use firebug because it never happens using Firefox), everything works every time. I don't know whether this issue has anything to do with routing, and I've no idea even what to look at next. The strange thing is, when I debug, the intro page doesn't fully load every time. Only about 1 in 3 times does it fully load even if I've just cleared browser cache. When I run it through fiddler, it fully loads and works fine every time.

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  • drupal hook_menu_alter() for adding tabs

    - by EricP
    I want to add some tabs in the "node/%/edit" page from my module called "cssswitch". When I click "Rebuild Menus", the two new tabs are displayed, but they are displayed for ALL nodes when editing them, not just for the node "cssswitch". I want these new tabs to be displayed only when editing node of type "cssswitch". The other problem is when I clear all cache, the tabs completely dissapear from all edit pages. Below is the code I wrote. function cssswitch_menu_alter(&$items) { $node = menu_get_object(); //print_r($node); //echo $node->type; //exit(); if ($node->type == 'cssswitch') { $items['node/%/edit/schedulenew'] = array( 'title' => 'Schedule1', 'access callback'=>'user_access', 'access arguments'=>array('view cssswitch'), 'page callback' => 'cssswitch_schedule', 'page arguments' => array(1), 'type' => MENU_LOCAL_TASK, 'weight'=>4, ); $items['node/%/edit/schedulenew2'] = array( 'title' => 'Schedule2', 'access callback'=>'user_access', 'access arguments'=>array('view cssswitch'), 'page callback' => 'cssswitch_test2', 'page arguments' => array(1), 'type' => MENU_LOCAL_TASK, 'weight'=>3, ); } } function cssswitch_test(){ return 'test'; } function cssswitch_test2(){ return 'test2'; } Thanks for any help.

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  • Hibernate JPA Caching Problem, Please help!

    - by Sameer Malhotra
    Ok, Here is my problem. I have a table named Master_Info_tbl. Its a lookup table: Here is the code for the table: @Entity @Table(name="MASTER_INFO_T") public class CodeValue implements java.io.Serializable { private static final long serialVersionUID = -3732397626260983394L; private Integer objectid; private String codetype; private String code; private String shortdesc; private String longdesc; private Integer dptid; private Integer sequen; private Timestamp begindate; private Timestamp enddate; private String username; private Timestamp rowlastchange; //getter Setter methods I have a service layer which calls the method       service.findbycodeType("Code1");   same way this table is queried for the other code types as well e.g. code2, code3 and so on till code10 which gets the result set from the same table and is shown into the drop down of the jsp pages since these drop downs are in 90% of the pages I am thinking to cache them globally. Any idea how to achieve this? FYI: I am using JPA and Hibernate with Struts2 and Spring. The database being used is DB2 UDB8.2 Please help!

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  • Reason for socket.error

    - by August Flanagan
    Hi, I am a complete newbie when it comes to python, and programming in general. I've been working on a little webapp for the past few weeks trying to improve my coding chops. A few days ago my laptop was stolen so I went out and got a new MacBook Pro. Thank God I had everything under subversion control. The problem is now that I am on my new machine a script that I was running has stopped working and I have no idea why. This is really the only part of what I have been writing that I borrowed heavily for existing scripts. It is from the widely available whois.py script and I have only slightly modified it as follows (see below). It was running fine on my old system (running ubuntu), but now the socket.error is being raised. I'm completely lost on this, and would really appreciate any help. Thanks! def is_available(domainname, whoisserver="whois.verisign-grs.com", cache=0): if whoisserver is None: whoisserver = "whois.networksolutions.com" s = None while s == None: try: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.setblocking(0) try: s.connect((whoisserver, 43)) except socket.error, (ecode, reason): if ecode in (115, 150): pass else: raise socket.error, (ecode, reason) ret = select.select([s], [s], [], 30) if len(ret[1])== 0 and len(ret[0]) == 0: s.close() raise TimedOut, "on connect " s.setblocking(1) except socket.error, (ecode, reason): print ecode, reason time.sleep(1) s = None s.send("%s \n\n" % domainname) page = "" while 1: data = s.recv(8196) if not data: break page = page + data s.close()

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  • Refresh page in browser without resubmitting form

    - by Michael
    I'm an ASP.NET developer, and I usually find myself leaving the webpage that I'm working on open in my browser (Chrome is my browser of choice, but this question is relevant for any browser). My workflow typically goes like this: I write code, I rebuild my project in Visual Studio, and then I flip back to my browser with Alt-Tab and hit F5 to refresh the page. This is fine and dandy if a form hasn't been submitted since the page was opened. But if I've been clicking around on ASP.NET form controls, the page has posted form data a number of times, so hitting F5 causes the browser to (sensibly) pop up a confirmation message, e.g., "Confirm Form Resubmission: The page that you're looking for used information that you entered...". Sometimes I do want to resubmit the form, but more often than not, I just want to start over with the page (rather than resubmit form data). The way I usually get around this is to simply add some query string data to the URL so that the browser sees it as a fresh page request, e.g.: page.aspx becomes page.aspx? (or vice-versa). My question is: Is there a better way to quickly request a fresh version of a webpage (and not submit form data) in any of the major browsers? It seems like a no-brainer to me for web development, but maybe I'm missing something. What I'd love to see is something like the last item in this list: F5: refresh page Ctrl-F5: refresh page (and force cache refresh) Alt-F5: request fresh copy of the page without resubmitting the form

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  • unbuffered I/O in Linux

    - by stuck
    I'm writing lots and lots of data that will not be read again for weeks - as my program runs the amount of free memory on the machine (displayed with 'free' or 'top') drops very quickly, the amount of memory my app uses does not increase - neither does the amount of memory used by other processes. This leads me to believe the memory is being consumed by the filesystems cache - since I do not intend to read this data for a long time I'm hoping to bypass the systems buffers, such that my data is written directly to disk. I dont have dreams of improving perf or being a super ninja, my hope is to give a hint to the filesystem that I'm not going to be coming back for this memory any time soon, so dont spend time optimizing for those cases. On Windows I've faced similar problems and fixed the problem using FILE_FLAG_NO_BUFFERING|FILE_FLAG_WRITE_THROUGH - the machines memory was not consumed by my app and the machine was more usable in general. I'm hoping to duplicate the improvements I've seen but on Linux. On Windows there is the restriction of writing in sector sized pieces, I'm happy with this restriction for the amount of gain I've measured. is there a similar way to do this in Linux?

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  • local vs core contoller

    - by latvian
    Hi, I am adding new column and action in the local admin app/code/local/Mage/Adminhtml/Block/Catalog/Product/Grid.php which works fine, however. The local controller/app/code/local/Mage/Adminhtml/Block/Catalog/Product.php is not being used or is not overloading the admin one /app/code/core/Mage/Adminhtml/Block/Catalog/Product.php. This is almost fresh install of Magento 1.4.0.1. I am the only one working, so i know it is not overloaded by some custom controller. I have disabled all custom modules. I have rolled back most of my changes. I have checked /etc/Modules/Mage_Catalog.xml. Refreshed cache all possible ways, loged in and out. Nothing....still using the core contoller copy. why? How do you troubleshoot, meaning, at what moment magento decides using between core or local copies? ...its even more strange because it does not parse local Adminhtml config.xml but uses local Adminthml copy of Blocks. Any pointer would help. I would like to keep everything in local code. Thank You, Margots

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  • How do I avoid a race condition in my Rails app?

    - by Cathal
    Hi, I have a really simple Rails application that allows users to register their attendance on a set of courses. The ActiveRecord models are as follows: class Course < ActiveRecord::Base has_many :scheduled_runs ... end class ScheduledRun < ActiveRecord::Base belongs_to :course has_many :attendances has_many :attendees, :through => :attendances ... end class Attendance < ActiveRecord::Base belongs_to :user belongs_to :scheduled_run, :counter_cache => true ... end class User < ActiveRecord::Base has_many :attendances has_many :registered_courses, :through => :attendances, :source => :scheduled_run end A ScheduledRun instance has a finite number of places available, and once the limit is reached, no more attendances can be accepted. def full? attendances_count == capacity end attendances_count is a counter cache column holding the number of attendance associations created for a particular ScheduledRun record. My problem is that I don't fully know the correct way to ensure that a race condition doesn't occur when 1 or more people attempt to register for the last available place on a course at the same time. My Attendance controller looks like this: class AttendancesController < ApplicationController before_filter :load_scheduled_run before_filter :load_user, :only => :create def new @user = User.new end def create unless @user.valid? render :action => 'new' end @attendance = @user.attendances.build(:scheduled_run_id => params[:scheduled_run_id]) if @attendance.save flash[:notice] = "Successfully created attendance." redirect_to root_url else render :action => 'new' end end protected def load_scheduled_run @run = ScheduledRun.find(params[:scheduled_run_id]) end def load_user @user = User.create_new_or_load_existing(params[:user]) end end As you can see, it doesn't take into account where the ScheduledRun instance has already reached capacity. Any help on this would be greatly appreciated.

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