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  • Rails: blank page - no errors or stack trace

    - by Nathan Long
    I've been trying to fix a bug in the Rails app I'm developing, and I keep getting a blank screen with no errors. I haven't found anything helpful in development.log, either (though it does show queries being run and such). Finally, I started to wonder if it's somehow set not to show errors anymore. I tried commenting out a necessary route, and sure enough, I got a blank page instead of the error and stack trace I expected. What might cause this? (I wondered if maybe I'm accidentally running production mode and errors aren't supposed to show then, but development.log is being appended, and if I open script/console and echo ENV['RAILS_ENV'], it says development.)

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  • Conditionals in Antlr String Templates

    - by Pat Long - Munkii Yebee
    We are using Antlr StringTemplates to give control over how a Entity's Name is output. The basic Stringtemplate is $FirstName$ $Initial$ $LastName$, $Suffix$, $Degree$ I want to add some smarts to that template so that the commas are only output when necessary i.e. The first comma is only output when there is a Suffix or Degree and the second commas is only output if there is a suffix. I tried the following template string bit it does not work. I guess I have misunderstood $FirstName$ $Initial$ $LastName$ <if(Suffix|Degree)>,<endif>, $Suffix$ <if(Suffix)>,<endif> $Degree$ If it helps we process the templates using this C# StringTemplate stringtemplate = new Antlr.StringTemplate.StringTemplate(template.Data); foreach (Pair<string, string> pair in dictionary) { if (pair.First != null && pair.Second != null) { stringtemplate.SetAttribute(pair.First, pair.Second); } } return stringtemplate.ToString();

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  • jCarousel, IE6 and Fixed Width

    - by Pat Long - Munkii Yebee
    We are using jCarousel on our websites to display images. Simple enough. We have fairly flexible layouts so the carousels are not always the same width. FF, IE7+, Chrome, Safari etc work perfectly well taking up the space available. However IE6 ends up sending the jCarousel script into a loop and warns that a script is stopping the page from loading correctly. To stop IE6 from failing we are having to specify a fixed width in CSS for the carousel container. Is this a problem that others have had with IE6 and jCarousel?

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  • Static Javascript files not loaded in Express app

    - by Dave Long
    I have an express app that has a bunch of static javascript files that aren't being loaded even though they are registered in my app.js file. Even public scripts (like jQuery: http://ajax.googleapis.com/ajax/libs/jquery/1.6.3/jquery.min.js) aren't processing. I can see the script tags in the generated html, but none of the functionality runs and I can't see the files loading in the web inspector. Here is the code that I have: app.js var express = require('express') var app = module.exports = express.createServer(); // Configuration var port = process.env.PORT || 3000; app.configure(function(){ app.set('views', __dirname + '/views'); app.set('view engine', 'jade'); app.use(express.bodyParser()); app.use(express.methodOverride()); app.use(app.router); app.use(express.static(__dirname + '/public')); }); app.configure('development', function(){ app.use(express.errorHandler({ dumpExceptions: true, showStack: true })); }); app.configure('production', function(){ app.use(express.errorHandler()); }); // Routes app.get('/manage/new', function(req, res){ res.render('manage/new', { title: 'Create a new widget' }); }) app.listen(port); console.log("Express server listening on port %d in %s mode", app.address().port, app.settings.env); /views/manage/layout.jade !!! 5 html(lang="en") head title= title link(rel="stylesheet", href="/stylesheets/demo.css") link(rel="stylesheet", href="/stylesheets/jquery.qtip.css") script(type="text/javascript", href="http://ajax.googleapis.com/ajax/libs/jquery/1.6.3/jquery.min.js") body!= body script(type="text/javascript", href="/javascripts/jquery.formalize.js") script(type="text/javascript", href="/javascripts/jquery.form.js") script(type="text/javascript", href="/javascripts/jquery.qtip.js") script(type="text/javascript", href="/javascripts/formToWizard.js") script(type="text/javascript", href="/javascripts/widget.js") /views/manage/new.jade h1= title div(style="float:left;") form(action="/manage/generate", method="post", enctype="multipart/form-data", name="create-widget") .errors fieldset legend Band / Album Information fieldset legend Social Networks fieldset legend Download All of my javascript files are stored in /public/javascripts and all of my static CSS files are being served up just fine. I'm not sure what I've done wrong.

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  • Testing Silverlight install detection

    - by Pat Long - Munkii Yebee
    I have implemented a silverlight install process inline with the best practive approach described in Microsoft's "Installation Experience White Paper - Apr 2009". I want to test out the following user scenarios Old version of Silverlight No Silverlight Cross browser In the past I have seen tools for uninstalling and installing different versions of Flash for this same type of testing. Is there anything like that for Silverlight? I know I can disable the plug ins but that is not the same IMHO TIA Pat

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  • How does session_start lock in PHP?

    - by Morgan Cheng
    Originally, I just want to verify that session_start locks on session. So, I create a PHP file as below. Basically, if the pageview is even, the page sleeps for 10 seconds; if the pageview is odd, it doesn't. And, session_start is used to obtain the page view in $_SESSION. I tried to access the page in two tabs of one browser. It is not surprising that the first tab takes 10 seconds since I explicitly let it sleep. The second tab would not sleep, but it should be blocked by sessiont_start. That works as expected. To my surprise, the output of the second page shows that session_start takes almost no time. Actually, the whole page seems takes no time to load. But, the page does take 10 seconds to show in browser. obtained lock Cost time: 0.00016689300537109 Start 1269739162.1997 End 1269739162.1998 allover time elpased : 0.00032305717468262 The page views: 101 Does PHP extract session_start out of PHP page and execute it before other PHP statements? This is the code. <?php function float_time() { list($usec, $sec) = explode(' ', microtime()); return (float)$sec + (float)$usec; } $allover_start_time = float_time(); $start_time = float_time(); session_start(); echo "obtained lock<br/>"; $end_time = float_time(); $elapsed_time = $end_time - $start_time; echo "Cost time: $elapsed_time <br>"; echo "Start $start_time<br/>"; echo "End $end_time<br/>"; ob_flush(); flush(); if (isset($_SESSION['views'])) { $_SESSION['views'] += 1; } else { $_SESSION['views'] = 0; } if ($_SESSION['views'] % 2 == 0) { echo "sleep 10 seconds<br/>"; sleep(10); } $allover_end_time = float_time(); echo "allover time elpased : " . ($allover_end_time - $allover_start_time) . "<br/>"; echo "The page views: " . $_SESSION['views']; ?>

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  • How to build Graceful Degradation AJAX web page?

    - by Morgan Cheng
    I want to build web page with "Graceful Degradation". That is, the web page functions even javascript is disabled. Now I have to make design decision on the format of AJAX response. If javascript is disabled, each HTTP request to server will generate HTML as response. The browser refreshes with the returned HTML. That's fine. If javascript is enabled, each AJAX HTTP request to server will generate ... well, JSON or HTML. If it is HTML, it is easy to implement. Just have javascript to replace part of page with the returned HTML. And, in server side, not much code change is needed. If it is JSON, then I have to implement JSON-to-html logic in javascript again which is almost duplicate of server side logic. Duplication is evil. I really don't like it. The benefit is that the bandwidth usage is better than HTML, which brings better performance. So, what's the best solution to Graceful Degradation? AJAX request better to return JSON or HTML?

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  • Elegant Algorithm for Parsing Data Stream Into Record

    - by Matt Long
    I am interfacing with a hardware device that streams data to my app over Wifi. The data is streaming in just fine. The data contains a character header (DATA:) that indicates a new record has begun. The issues is that the data I receive doesn't necessarily fall on the header boundary, so I have to capture the data until what I've captured contains the header. Then, everything that precedes the header goes into the previous record and everything that comes after it goes into a new record. I have this working, but wondered if anyone has done this before and has a good computer-sciencey way to solve the problem. Here's what I do: Convert the NSData of the current read to an NSString Append the NSString to a placeholder string Check placeholder string for the header (DATA:). If the header is not there, just wait for the next read. If the header exists, append whatever precedes it to a previous record placeholder and hand that placeholder off to an array as a complete record that I can further parse into fields. Take whatever shows up after the header and place it in the record placeholder so that it can be appended to in the next read. Repeat steps 3 - 5. Let me know if you see any flaws with this or have a suggestion for a better way. Seems there should be some design pattern for this, but I can't think of one. Thanks.

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  • Use auto_ptr in VC6 dll cause crash

    - by Yan Cheng CHEOK
    // dll #include <memory> __declspec(dllexport) std::auto_ptr<int> get(); __declspec(dllexport) std::auto_ptr<int> get() { return std::auto_ptr<int>(new int()); } // exe #include <iostream> #include <memory> __declspec(dllimport) std::auto_ptr<int> get(); int main() { { std::auto_ptr<int> x = get(); } std::cout << "done\n"; getchar(); } The following code run perfectly OK under VC9. However, under VC6, I will experience an immediate crash with the following message. Debug Assertion Failed! Program: C:\Projects\use_dynamic_link\Debug\use_dynamic_link.exe File: dbgheap.c Line: 1044 Expression: _CrtIsValidHeapPointer(pUserData) Is it exporting auto_ptr under VC6 is not allowed? It is a known problem that exporting STL collection classes through DLL. http://stackoverflow.com/questions/2451714/access-violation-when-accessing-an-stl-object-through-a-pointer-or-reference-in-a However, I Google around and do not see anything mention for std::auto_ptr. Any workaround?

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  • Multiple Tables or Multiple Schema

    - by Yan Cheng CHEOK
    http://stackoverflow.com/questions/1152405/postgresql-is-better-using-multiple-databases-with-1-schema-each-or-1-database I am new in schema concept for PostgreSQL. For the above mentioned scenario, I was wondering Why don't we use a single database (with default schema named public) Why don't we have a single table, to store multiple users row? Other tables which hold users related information, with foreign key point to the user table. Can anyone provide me a real case scenario, which single database, multiple schema will be extremely useful, and can't solve by conventional single database, single schema.

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  • Algorithm to detect how many words typed, also multi sentence support (Java)

    - by Alex Cheng
    Hello all. Problem: I have to design an algorithm, which does the following for me: Say that I have a line (e.g.) alert tcp 192.168.1.1 (caret is currently here) The algorithm should process this line, and return a value of 4. I coded something for it, I know it's sloppy, but it works, partly. private int counter = 0; public void determineRuleActionRegion(String str, int index) { if (str.length() == 0 || str.indexOf(" ") == -1) { triggerSuggestionList(1); return; } //remove duplicate space, spaces in front and back before searching int num = str.trim().replaceAll(" +", " ").indexOf(" ", index); //Check for occurances of spaces, recursively if (num == -1) { //if there is no space //no need to check if it's 0 times it will assign to 1 triggerSuggestionList(counter + 1); counter = 0; return; //set to rule action } else { //there is a space counter++; determineRuleActionRegion(str, num + 1); } } //end of determineactionRegion() So basically I find for the space and determine the region (number of words typed). However, I want it to change upon the user pressing space bar <space character>. How may I go around with the current code? Or better yet, how would one suggest me to do it the correct way? I'm figuring out on BreakIterator for this case... To add to that, I believe my algorithm won't work for multi sentences. How should I address this problem as well. -- The source of String str is acquired from textPane.getText(0, pos + 1);, the JTextPane. Thanks in advance. Do let me know if my question is still not specific enough.

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  • How can I test caching and cache busting?

    - by Nathan Long
    In PHP, I'm trying to steal a page from the Rails playbook (see 'Using Asset Timestamps' here): By default, Rails appends assets' timestamps to all asset paths. This allows you to set a cache-expiration date for the asset far into the future, but still be able to instantly invalidate it by simply updating the file (and hence updating the timestamp, which then updates the URL as the timestamp is part of that, which in turn busts the cache). It‘s the responsibility of the web server you use to set the far-future expiration date on cache assets that you need to take advantage of this feature. Here‘s an example for Apache: # Asset Expiration ExpiresActive On <FilesMatch "\.(ico|gif|jpe?g|png|js|css)$"> ExpiresDefault "access plus 1 year" </FilesMatch> If you look at a the source for a Rails page, you'll see what they mean: the path to a stylesheet might be "/stylesheets/scaffold.css?1268228124", where the numbers at the end are the timestamp when the file was last updated. So it should work like this: The browser says 'give me this page' The server says 'here, and by the way, this stylesheet called scaffold.css?1268228124 can be cached for a year - it's not gonna change.' On reloads, the browser says 'I'm not asking for that css file, because my local copy is still good.' A month later, you edit and save the file, which changes the timestamp, which means that the file is no longer called scaffold.css?1268228124 because the numbers change. When the browser sees that, it says 'I've never seen that file! Give me a copy, please.' The cache is 'busted.' I think that's brilliant. So I wrote a function that spits out stylesheet and javascript tags with timestamps appended to the file names, and I configured Apache with the statement above. Now: how do I tell if the caching and cache busting are working? I'm checking my pages with two plugins for Firebug: Yslow and Google Page Speed. Both seem to say that my files are caching: "Add expires headers" in Yslow and "leverage browser caching" in Page Speed are both checked. But when I look at the Page Speed Activity, I see a lot of requests and waiting and no 'cache hits'. If I change my stylesheet and reload, I do see the change immediately. But I don't know if that's because the browser never cached in the first place or because the cache is busted. How can I tell?

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  • Subversion Repository Layout

    - by Tim Long
    Most subversion tools create a default repository layout with /trunk, /branches and /tags. The documentation also recommends not using separate repositories for each project, so that code can be more easily shared. Following that advice has led to me having a repository with the following layout: /trunk /Project1 /Project2 /branches /Project1 /Project2 /tags /Project1 /Project2 and so on, you get the idea. Over time, I've found this structure a bit clumsy and it occurred to me that there's an alternative interpretation of the recommendations, such as: /Project1 /trunk /branches /tags /Project2 /trunk /branches /tags So, which layout do people use, and why? Or - is there another way to do things that I've completely missed?

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  • NSString stringWithFormat: with C array?

    - by Chris Long
    Hi, I'm writing a program that calculates the Jacobi algorithm. It's written in Objective-C since it runs on a Mac, but the majority is written in standard C. I'm using a two-dimensional C array and an NSArray containing 5 NSTextField labels. The following code yields an EXC_BAD_ACCESS error: for ( int i = 0; i < 5; i++ ) { NSString *resultString = [NSString stringWithFormat:@"%g", matrix[i][i] ]; [[resultLabels objectAtIndex:i] setStringValue:resultString]; // error line } Any help?

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  • Using Custom MapType with Google Maps API

    - by Pat Long - Munkii Yebee
    I realise there are a couple of examples such as Maoki's Add Your Own Custom Map and Mike Williams' [link text][Google Maps API Tutorial] however I have looked at these and still end up with a Grey box. The API will not call my "getTileUrl" callback function. This is the javascript I am using var map = new GMap2(document.getElementById("map")); map.setUIToDefault(); var copyCollection = new GCopyrightCollection('Map Data:'); var copyright = new GCopyright(1, new GLatLngBounds(new GLatLng(-90, -180), new GLatLng(90, 180)), 0, "©2006 RunwayFinder.com"); copyCollection.addCopyright(copyright); var tilelayers = [new GTileLayer(copyCollection, 3, 11)]; tilelayers[0].getTileUrl = function (a, b) { var z = 17 - b; var f = "http://localhost:25213/test.jpg?x=" + a.x + "&y=" + a.y + "&zoom=" + z + "&width=100&height=100"; return f; }; var custommap = new GMapType(tilelayers, new GMercatorProjection(12), "Chart", { errorMessage: "No chart data available" }); map.addMapType(custommap); Can anyone see what it is i am doing wrong?

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  • Grails validateable not work for non-persistent domain class

    - by Hoàng Long
    I followed the instruction here: http://www.grails.org/doc/latest/guide/7.%20Validation.html and added into config.groovy: grails.validateable.classes = [liningtest.Warm'] Then added in src/groovy/Warm.groovy (it's a non-persistent domain class): package liningtest import org.codehaus.groovy.grails.validation.Validateable class Warm { String name; int happyCite; Warm(String n, int h) { this.name = n; this.happyCite = h; } static constraints = { name(size: 1..50) happyCite(min: 100) } } But it just doesn't work (both "blank false" & "size: 0..25") for the "hasErrors" function. It always returns false, even when the name is 25. Is this a Grails bug, if yes, is there any work-around? I'm using Grails 1.3.3 UPDATE: I have updated the simplified code. And now I know that constraint "size" can't be used with "blank", but still does not work. My test class in test/unit/liningtest/WarmTests.groovy package liningtest import grails.test.* class WarmTests extends GrailsUnitTestCase { protected void setUp() { super.setUp() } protected void tearDown() { super.tearDown() } void testSomething() { def w = new Warm('Hihi', 3) assert (w.happyCite == 3) assert (w.hasErrors() == true) } } And the error I got: <?xml version="1.0" encoding="UTF-8" ?> <testsuite errors="1" failures="0" hostname="evolus-50b0002c" name="liningtest.WarmTests" tests="1" time="0.062" timestamp="2010-12-16T04:07:47"> <properties /> <testcase classname="liningtest.WarmTests" name="testSomething" time="0.062"> <error message="No signature of method: liningtest.Warm.hasErrors() is applicable for argument types: () values: [] Possible solutions: hashCode()" type="groovy.lang.MissingMethodException">groovy.lang.MissingMethodException: No signature of method: liningtest.Warm.hasErrors() is applicable for argument types: () values: [] Possible solutions: hashCode() at liningtest.WarmTests.testSomething(WarmTests.groovy:18) </error> </testcase> <system-out><![CDATA[--Output from testSomething-- ]]></system-out> <system-err><![CDATA[--Output from testSomething-- ]]></system-err> </testsuite> UPDATE 2: When I don't use Unit test, but try to call hasErrors in the controller, it runs but return false value. (hasErrors return false with Warm('Hihi', 3) ). Does anyone has a clue?

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  • UIView Obscuring Other Views

    - by Matt Long
    I cannot figure out what is obscuring my buttons. The first image shows the buttons that I want to click. They are clickable while the view is contracted like this, but when the view is expanded like in the second image, the buttons are no longer clickable. There seems to be another view obscuring the buttons. Any thoughts on what might be causing that? If not, any idea how I can figure out what view is getting the tap events when I tap in that area? Thanks. -Matt

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  • Help to Install Eclipse for A Netbeans Users

    - by Yan Cheng CHEOK
    I had been using Netbeans all the while to develop Swing application. So far, I am a Happy Netbeans User Currently, I had a project (GWT, J2EE and Swing), which I need to use Eclipse (Please do not ask Why) Here is the step I had been taken. Download Eclipse IDE for Java EE Developers (190 MB) from http://www.eclipse.org/downloads/ I thought this should be the correct choice, as I see most features are found in that edition http://www.eclipse.org/downloads/packages/compare-packages After struggling a while to get use to the user interface of Eclipse, I still cannot find a Visual GUI Editor! After doing some Googling, I realize I need to install something called Plugins However, tones of plugins which had similar features has confused me, as I found http://www.cloudgarden.com/jigloo/index.html http://www.eclipse.org/vep/WebContent/main.php http://code.google.com/p/visualswing4eclipse/ This makes me even more confuse? Which plugin I should use to develop a Swing based application? Most of them seems not up-to-dated. Or, is there any complete bundle I can download, where 1 click, will install all the necessary Swing development tools for me? I just miss my Netbeans :( I really appreciate their team, who make the installation work so easy. One click button install, all the necessary tools just come to me

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  • Java OutOfMemoryError message changes when trying to create Arrays of different sizes

    - by Gordon
    In the question by DKSRathore How to simulate the Out Of memory : Requested array size exceeds VM limit some odd behavior was noted when creating an arrays. When creating an array of size Integer.MAX_VALUE an exception with the error java.lang.OutOfMemoryError Requested array size exceeds VM limit was thrown. However when an array was created with a size less than the max but still above the virtual machine memory limit the error message read java.lang.OutOfMemoryError: Java heap space. Testing further I managed to narrow down where the error messages changes. long[] l = new long[2147483645]; exceptions message reads - Requested array size exceeds VM limit long[] l = new long[2147483644]; exceptions message reads - Java heap space errors I increased my virtual machine memory and still produced the same result. Has anyone any idea why this happens? Some extra info: Integer.MAX_VALUE = 2147483647. Edit: Here's the code I used to find the value, might be helpful. int max = Integer.MAX_VALUE; boolean done = false; while (!done) { try { max--; // Throws an error long[] l = new long[max]; // Exit if an error is no longer thrown done = true; } catch (OutOfMemoryError e) { if (!e.getMessage().contains("Requested array size exceeds VM limit")) { System.out.println("Message changes at " + max); done = true; } } }

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  • Did I find a bug in PHP's `crypt()`?

    - by Nathan Long
    I think I may have found a bug in PHP's crypt() function under Windows. However: I recognize that it's probably my fault. PHP is used by millions and worked on by thousands; my code is used by tens and worked on by me. (This argument is best explained on Coding Horror.) So I'm asking for help: show me my fault. I've been trying to find it for a few days now, with no luck. The setup I'm using a Windows server installation with Apache 2.2.14 (Win32) and PHP 5.3.2. My development box runs Windows XP Professional; the 'production' server (this is an intranet setup) runs Windows Storage Server 2003. The problem happens on both. I don't see anything in php.ini related to crypt(), but will happily answer questions about my config. The problem Several scripts in my PHP app occasionally hang: the page sits there on 'waiting for localhost' and never finishes. Each of these scripts uses crypt to hash a user's password before storing it in the database, or, in the case of the login page, to hash the entered password before comparing it to the version stored in the database. Since the login page is the simplest, I focused on it for testing. I repeatedly logged in, and found that it would hang maybe 4 out of 10 times. As an experiment, I changed the login page to use the plain text password and changed my password in the database to its plain text version. The page stopped hanging. I saw that PHP's latest version lists this bugfix: Fixed bug #51059 (crypt crashes when invalid salt are [sic] given). So I created a very simple test script, as follows, using the same salt given in an official example: $foo = crypt('rasmuslerdorf','r1'); echo $foo; This page, too, will hang, if I reload it like crazy. I only see it hanging in Chrome, but regardless of browser, the effect on Apache is the same. Effect on Apache When these pages hang, Apache's server-status page (which I explained here, regarding a different problem) increments the number of requests being processed and decrements the number of idle workers. The requests being processed almost all have a status of 'Sending Reply,' though sometimes for a moment they will show either 'Reading request' or 'keepalive (read).' Eventually, Apache may crash. When it does, the Windows crash report looks like this: szAppName: httpd.exe szAppVer: 2.2.14.0 szModName: php5ts.dll szModVer: 5.3.1.0 // OK, this report was before I upgraded to PHP 5.3.2, // but that didn't fix it offset: 00a2615 Is it my fault? I'm tempted to file a bug report to PHP on this. The argument against it is, as stated above, that bugs are nearly always my fault. However, my argument in favor of 'it's PHP's fault' is: I'm using Windows, whereas most servers use Linux (I don't get to choose this), so the chances are greater that I've found an edge case There was recently a bug with crypt(), so maybe it still has issues I have made the simplest test case I can, and I still have the problem Can anyone duplicate this? Can you suggest where I've gone wrong? Should I file the bug after all? Thanks in advance for any help you may give.

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  • How to troubleshoot PHP session file empty issue?

    - by Morgan Cheng
    I have a very simple test page for PHP session. <?php session_start(); if (isset($_SESSIONS['views'])) { $_SESSIONS['views'] = $_SESSIONS['pv'] + 1; } else { $_SESSIONS['views'] = 0; } var_dump($_SESSIONS); ?> After refreshing the page, it always show array 'views' => int 0 The environment is XAMPP 1.7.3. I checked phpInfo(). The session is enabled. Session Support enabled Registered save handlers files user sqlite Registered serializer handlers php php_binary wddx Directive Local Value Master Value session.auto_start Off Off session.bug_compat_42 On On When the page is accessed, there is session file sess_lnrk7ttpai8187v9q6iok74p20 created in my "D:\xampp\tmp" folder. But the content is empty. With Firebug, I can see cookies about the session. Cookie PHPSESSID=lnrk7ttpai8187v9q6iok74p20 It seems session data is not flushed to files. Is there any way or direction to trouble shoot this issue? Thanks.

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  • Rails : fighting long http response times with ajax. Is it a good idea? Please, help with implementa

    - by baranov
    Hi, everybody! I've googled some tutorials, browsed some SO answers, and was unable to find a recipe for my problem. I'm writing a web site which is supposed to display almost realtime stock chart. Data is stored in constantly updating MySQL database, I wrote a find_by_sql query code which fetches all the data I need to get my chart drawn. Everything is ok, except performance - it takes from one second to one minute for different queries to fetch all the data from the database, this time includes necessary (My)SQL-server side calculations. This is simply unacceptable. I got the following idea: if the data is queried from the MySQL server one point a time instead of entire dataset, it takes only about 1-100ms to get an individual point. I imagine the data fetch process might be browser-driven. After the user presses the button in order to get a chart drawn, controller makes one request to the database and renders, say, a progress bar, say 1% ready. When the browser gets the response, it immediately makes an (ajax) request, and the server fetches the next piece of data and renders "2%". And so on, until all the data is ready and the server displays the requested chart. Could this be implemented in rails+js, is there a tutorial for solving a similar problem on the Web? I suppose if the thing is feasible at all, somebody should have already done this before. I have read several articles about ajax, I believe I do understand general principles, but never did nontrivial ajax programming myself. Thanks for your time!

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