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1k of Program Space, 64 bytes of RAM. Is 1 wire communication possible?

- by Earlz

(If your lazy see bottom for TL;DR) Hello, I am planning to build a new (prototype) project dealing with physical computing. Basically, I have wires. These wires all need to have their voltage read at the same time. More than a few hundred microseconds difference between the readings of each wire will completely screw it up. The Arduino takes about 114 microseconds. So the most I could read is 2 or 3 wires before the latency would skew the accuracy of the readings. So my plan is to have an Arduino as the "master" of an array of ATTinys. The arduino is pretty cramped for space, but it's a massive playground compared to the tinys. An ATTiny13A has 1k of flash ROM(program space), 64 bytes of RAM, and 64 bytes of (not-durable and slow) EEPROM. (I'm choosing this for price as well as size) The ATTinys in my system will not do much. Basically, all they will do is wait for a signal from the Master, and then read the voltage of 1 or 2 wires and store it in RAM(or possibly EEPROM if it's that cramped). And then send it to the Master using only 1 wire for data.(no room for more than that!). So far then, all I should have to do is implement trivial voltage reading code (using built in ADC). But this communication bit I'm worried about. Do you think a communication protocol(using just 1 wire!) could even be implemented in such constraints? TL;DR: In less than 1k of program space and 64 bytes of RAM(and 64 bytes of EEPROM) do you think it is possible to implement a 1 wire communication protocol? Would I need to drop to assembly to make it fit? I know that currently my Arduino programs linking to the Wiring library are over 8k, so I'm a bit concerned.

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loading google maps drawing manager object

- by psychok7

So i am using Google Maps Drawing Manager to draw some polygons and i am saving the lat e long coordinates to my database. Now my question is, after i load that to my array, how can i rebuild the saved polygon back into my map? I can't seem to find a code to understand that. this is what i have now : window.initialize_2 = function () { var mapOptions = { center: new google.maps.LatLng(-34.397, 150.644), zoom: 8, mapTypeId: google.maps.MapTypeId.ROADMAP }; var map = maplimits; var drawingManager = new google.maps.drawing.DrawingManager({ drawingMode: google.maps.drawing.OverlayType.MARKER, drawingControl: true, drawingControlOptions: { position: google.maps.ControlPosition.TOP_CENTER, drawingModes: [ google.maps.drawing.OverlayType.POLYGON] }, markerOptions: { icon: 'images/beachflag.png' }, polygonOptions: { fillColor: '#ffff00', fillOpacity: 10, strokeWeight: 5, clickable: true, editable: true, zIndex: 1 } }); var coord_listener = google.maps.event.addListener(drawingManager, 'polygoncomplete', function (polygon) { var coordinates = (polygon.getPath().getArray()); console.log(coordinates); window.poly = polygon; }); //delete shape google.maps.event.addListener(drawingManager, 'overlaycomplete', function (e) { if (e.type != google.maps.drawing.OverlayType.MARKER) { // Switch back to non-drawing mode after drawing a shape. drawingManager.setDrawingMode(null); // Add an event listener that selects the newly-drawn shape when the user // mouses down on it. var newShape = e.overlay; newShape.type = e.type; google.maps.event.addListener(newShape, 'click', function () { setSelection(newShape); }); setSelection(newShape); } }); // Clear the current selection when the drawing mode is changed, or when the // map is clicked. google.maps.event.addListener(drawingManager, 'drawingmode_changed', clearSelection); google.maps.event.addListener(map, 'click', clearSelection); drawingManager.setMap(map); }

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Returning a variable in a public void...

- by James Rattray

Hello, I'm abit new to programming Android App's, however I have come across a problem, I can't find a way to make global variables -unlike other coding like php or VB.NET, are global variables possible? If not can someone find a way (and if possible implement the way into the code I will provide below) to get a value from the variable 'songtoplay' so I can use in another Public Void... Here is the code: final Spinner hubSpinner = (Spinner) findViewById(R.id.myspinner); ArrayAdapter adapter = ArrayAdapter.createFromResource( this, R.array.colours, android.R.layout.simple_spinner_item); adapter .setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item); hubSpinner.setAdapter(adapter); // hubSpinner.setOnItemSelectedListener(new OnItemSelectedListener() { public void onItemSelected(AdapterView<?> parentView, View selectedItemView, int position, long id) { //code Object ttestt = hubSpinner.getSelectedItem(); final String test2 = ttestt.toString(); Toast message1 = Toast.makeText(Textbox.this, test2, Toast.LENGTH_LONG); message1.show(); String songtoplay = test2; // Need songtoplay to be available in another 'Public Void' } public void onNothingSelected(AdapterView<?> parentView) { //Code } }); Basically, it gets the value from the Spinner 'hubSpinner' and displays it in a Toast. I then want it to return a value for string variable 'songtoplay' -or find a way to make it global or useable in another Public Void, (Which is will a button, -loading the song to be played) Please help me, Thanks alot. James

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String operations

- by NEO

I am trying to find the most repeated word in a string. My code is as follows: public class Word { private String toWord; private int Count; public Word(int count, String word){ toWord = word; Count = count; } public static void main(String args[]){ String str="my name is neo and my other name is also neo because I am neo"; String []str1=str.split(" "); Word w1=new Word(0,str1[0]); LinkedList<Word> list = new LinkedList<Word>(); list.add(w1); ListIterator itr = list.listIterator(); for(int i=1;i<str1.length;i++){ while(itr.hasNext()){ if(str1[i].equalsTO(????)); else list.add(new Word(0,str1[i])); } How do I compare the string from string array str1 to the string stored in the linked list and then how do i increase the respective count. I will then print the string with the highest count, I dont know how to do that either.

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What is the form_for syntax for nested resources?

- by Kris

I am trying to create a form for a nested resource. Here is my route: map.resources :websites do |website| website.resources :domains end Here are my attempts and the errors: <% form_for(@domain, :url => website_domains_path(@website)) do | form | %> <%= form.text_field :name %> # ArgumentError: wrong number of arguments (1 for 0) # form_helper.rb:290:in 'respond_to?' # form_helper.rb:290:in 'apply_form_for_options!' # form_helper.rb:277:in 'form_for' <% form_for([@website, @domain]) do | form | %> <%= form.text_field :name %> # ArgumentError: wrong number of arguments (1 for 0) # form_helper.rb:290:in 'respond_to?' # form_helper.rb:290:in 'apply_form_for_options!' # form_helper.rb:277:in 'form_for' <% form_for(:domain, @domain, :url => website_domains_path(@website)) do | form | %> <%= form.text_field :name %> # ArgumentError: wrong number of arguments (1 for 0) # wrapper.rb:14:in 'respond_to?' # wrapper.rb:14:in 'wrap' # active_record_helper.rb:174:in 'error_messages_for' <% form_for(:domain, [@website, @domain]) do | form | %> <%= form.text_field :name %> # UndefinedMethodError 'name' for #<Array:0x40fa498> I have confirmed both @website and @domain contain instances of the correct class. The routes also generate correctly is used like this for example, so I dont think their is an issue with the route or url helpers. <%= website_domains_path(1) %> <%= website_data_source_path(1, 1) %> Rails 2.3.5

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Inserting bits into byte

- by JB_SO

I was looking at an example of reading bits from a byte and the implementation looked simple and easy to understand. I was wondering if anyone has a similar example of how to insert bits into a byte or byte array, that is easier to understand and also implement like the example below. Here is the example I found of reading bits from a byte (http://bytes.com/topic/c-sharp/answers/505085-reading-bits-byte-file): static int GetBits3(byte b, int offset, int count) { return (b >> offset) & ((1 << count) - 1); } Here is what i'm trying to do....and this is my current implementation.....just a little confused with the bit-masking/shifting, etc, that's why I'm trying to find out if there is an easier way to do what i'm doing BYTE Msg[2]; Msg_Id = 3; Msg_Event = 1; Msg_Ready = 2; Msg[0] = ( ( Msg_Event << 4 ) & 0xF0 ) | ( Msg_Id & 0x0F ) ; Msg[1] = Msg_Ready & 0x0F; //MsgReady & Unused Thanks for your help!

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Can I delay the keyup event for jquery?

- by Paul

I'm using the rottentomatoes movie API in conjunction with twitter's typeahead plugin using bootstrap 2.0. I've been able to integerate the API but the issue I'm having is that after every keyup event the API gets called. This is all fine and dandy but I would rather make the call after a small pause allowing the user to type in several characters first. Here is my current code that calls the API after a keyup event: var autocomplete = $('#searchinput').typeahead() .on('keyup', function(ev){ ev.stopPropagation(); ev.preventDefault(); //filter out up/down, tab, enter, and escape keys if( $.inArray(ev.keyCode,[40,38,9,13,27]) === -1 ){ var self = $(this); //set typeahead source to empty self.data('typeahead').source = []; //active used so we aren't triggering duplicate keyup events if( !self.data('active') && self.val().length > 0){ self.data('active', true); //Do data request. Insert your own API logic here. $.getJSON("http://api.rottentomatoes.com/api/public/v1.0/movies.json?callback=?&apikey=MY_API_KEY&page_limit=5",{ q: encodeURI($(this).val()) }, function(data) { //set this to true when your callback executes self.data('active',true); //Filter out your own parameters. Populate them into an array, since this is what typeahead's source requires var arr = [], i=0; var movies = data.movies; $.each(movies, function(index, movie) { arr[i] = movie.title i++; }); //set your results into the typehead's source self.data('typeahead').source = arr; //trigger keyup on the typeahead to make it search self.trigger('keyup'); //All done, set to false to prepare for the next remote query. self.data('active', false); }); } } }); Is it possible to set a small delay and avoid calling the API after every keyup?

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How to get root as '/' with Kohana3, base_url and mod rewrite.

- by Drew

Hi all! I've only just started using Kohana ( 3 hours ago), and so far it's blown my socks off (and I'm wearing slippers, so that's quite impressive). Right now, I have a controller 'Controller_FrontPage' with associated views and models and I'm trying to get it accesible from the root of my website (eg, http://www.mysite.com/). If I edit the default controller in the bootstrap from: Route::set('default', '(<controller>(/<action>(/<id>)))') ->defaults(array( 'controller' => 'welcome', 'action' => 'index', )); to 'controller' => '', I get an error, could not find controller_ (which makes sense), and if I change it to 'controller' => '/', I get an error, could not find controller_/ (which also makes sense). If I set 'controller' => 'FrontPage', everything works fine, but all my links (html::anchor(...)) point to http://www.mysite.com/FrontPage/*. Is there a way to have all the anchors point to http://www.mysite.com/*?

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rails validation of presence not failing on nil

- by holden

I want to make sure an attibute exists, but it seems to still slip thru and I'm not sure how better to check for it. This should work, but doesn't. It's a attr_accessor and not a real attribute if that makes a difference. validates_presence_of :confirmed, :rooms {"commit"=>"Make Booking", "place_id"=>"the-kosmonaut", "authenticity_token"=>"Tkd9bfGqYFfYUv0n/Kqp6psXHjLU7CmX+D4UnCWMiMk=", "utf8"=>"âœ“", "booking"=>{"place_id"=>"6933", "bookdate"=>"2010-11-22", "rooms"=>[{}], "no_days"=>"2"}} Not sure why my form_for returns a blank hash in an array... <% form_for :booking, :url => place_bookings_path(@place) do |f| %> <%= f.hidden_field :bookdate, { :value => user_cart.getDate } %> <%= f.hidden_field :no_days, { :value => user_cart.getDays } %> <% for room in pricing_table(@place.rooms,@valid_dates) %> <%= select_tag("booking[rooms][][#{room.id}]", available_beds(room)) %> <% end %> <% end %>

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Where to post code for open source usage?

- by Douglas

I've been working for a few weeks now with the Google Maps API v3, and have done a good bit of development for the map I've been creating. Some of the things I've done have had to be done to add usability where there previously was not any, at least not that I could find online. Essentially, I made a list of what had to be done, searched all over the web for the ways to do what I needed, and found that some were not(at the time) possible(in the "grab an example off the web" sense). Thus, in my working on this map, I have created a number of very useful tools, which I would like to share with the development community. Is there anywhere I could use as a hub, apart from my portfolio ( http://dougglover.com ), to allow people to view and recycle my work? I know how hard it can be to need to do something, and be unable to find the solution elsewhere, and I don't think that if something has been done before, it should necessarily need to be written again and again. Hence open source code, right? Firstly, I was considering coming on here and asking a question, and then just answering it. Problem there is I assume that would just look like a big reputation grab. If not, please let me know and I'll go ahead and do that so people here can see it. Other suggestions appreciated. Some stuff I've made: A (new and improved) LatLng generator Works quicker, generates LatLng based on position of a draggable marker Allows searching for an address to place the marker on/near the desired location(much better than having to scroll to your location all the way from Siberia) Since it's a draggable marker, double-clicking zooms in, instead of creating a new LatLng marker like the one I was originally using The ability to create entirely custom "Smart Paths" Plot LatLng points on the map which connect to each other just like they do using the actual Google Maps Using Dijkstra's algorithm with Javascript, the routing is intelligent and always gives the shortest possible route, using the points provided Simple, easy to read multi-dimensional array system allows for easily adding new points to the grid Any suggestions, etc. appreciated.

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Problem with filefield module after migrating drupal site to a new server: cant upload files

- by oalo

We have a content type with two imagefield / filefield fields, and after migrating our site to a new server, we have the following problem: When we submit a new item for this content type, with two images for those fields, drupal gives us the following error and does not upload the images: warning: fopen(sites/default/files/.htaccess) [function.fopen]: failed to open stream: Permission denied in /websites/sitename/data/sites/all/modules/filefield/field_file.inc on line 349. warning: fopen(sites/default/files/.htaccess) [function.fopen]: failed to open stream: Permission denied in /websites/sitename/data/sites/all/modules/filefield/field_file.inc on line 349. An image thumbnail was not able to be created. warning: fopen(sites/default/files/.htaccess) [function.fopen]: failed to open stream: Permission denied in /websites/sitename/data/sites/all/modules/filefield/field_file.inc on line 349. warning: fopen(sites/default/files/.htaccess) [function.fopen]: failed to open stream: Permission denied in /websites/sitename/data/sites/all/modules/filefield/field_file.inc on line 349. An image thumbnail was not able to be created. I understand this is a permissions error, but it is not clear to me where do I have to change permissions. Line 349 of file.inc has the following code: if (($fp = fopen("$directory/.htaccess", 'w')) && fputs($fp, $htaccess_lines)) { fclose($fp); chmod($directory .'/.htaccess', 0664); } else { $repl = array('%directory' = $directory, '!htaccess' = nl2br(check_plain($htaccess_lines))); form_set_error($form_item, t("Security warning: Couldn't write .htaccess file. Please create a .htaccess file in your %directory directory which contains the following lines:!htaccess", $repl));

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Cookie not working after mod rewrite rule

- by moonwalker

Hi all, I have a simple Cookie to set the chosen language: $lang = $_GET['lang']; $myLang = $_COOKIE["myLang"]; if (!isset($_COOKIE["myLang"])){ setcookie("myLang", "en", $expire); include "languages/en.php"; $myLang = "en"; }else{ include "languages/$myLang.php"; } // One year to expire $expire = time()+60*60*24*30*365; // Put $languages in a common header file. $languages = array('en' => 1, 'fr' => 2, 'nl' => 3); if (array_key_exists($lang, $languages)) { include "languages/{$lang}.php"; setcookie("myLang", $lang, $expire); $myLang = $lang; } After using some rewrite rules, it just doesn't work anymore. I tried the following: setcookie("myLang", "en", $expire, "/" , false); No luck at all. This is my .htaccess file: <IfModule mod_rewrite.c> Options +FollowSymLinks Options +Indexes RewriteEngine On RewriteBase / RewriteRule ^sort/([^/]*)/([^/]*)$ /3arsi2/sort.php?mode=$1&cat=$2 [L] RewriteRule ^category/([^/]*)$ /3arsi2/category.php?cat=$1 [L] RewriteRule ^category/([^/]*)/([^/]*)$ /3arsi2/category.php?cat=$1&lang=$2 [L] RewriteRule ^search/([^/]*)$ /3arsi2/search.php?mode=$1 [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule ^u/([^/]+)/?$ 3arsi2/user.php?user=$1 [NC,L] RewriteRule ^u/([^/]+)/(images|videos|music)/?$ 3arsi2/user.php?user=$1&page=$2 [NC,L] RewriteRule ^([^\.]+)$ 3arsi2/$1.php [NC,L] </IfModule> Any idea how to solve this? I'm still new to the mod rewrite thing, so I still don't really understand the logic behind it all. Thanks for any help you can provide.

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Select all points in a matrix within 30m of another point

- by pinnacler

So if you look at my other posts, it's no surprise I'm building a robot that can collect data in a forest, and stick it on a map. We have algorithms that can detect tree centers and trunk diameters and can stick them on a cartesian XY plane. We're planning to use certain 'key' trees as natural landmarks for localizing the robot, using triangulation and trilateration among other methods, but programming this and keeping data straight and efficient is getting difficult using just Matlab. Is there a technique for sub-setting an array or matrix of points? Say I have 1000 trees stored over 1km (1000m), is there a way to say, select only points within 30m radius of my current location and work only with those? I would just use a GIS, but I'm doing this in Matlab and I'm unaware of any GIS plugins for Matlab. I forgot to mention, this code is going online, meaning it's going on a robot for real-time execution. I don't know if, as the map grows to several miles, using a different data structure will help or if calculating every distance to a random point is what a spatial database is going to do anyway. I'm thinking of mirroring two arrays, one sorted by X and the other by Y. Then bubble sorting to determine the 30m range in that. I do the same for both arrays, X and Y, and then have a third cross link table that will select the individual values. But I don't know, what that's called, how to program that and I'm sure someone already has so I don't want to reinvent the wheel. Cartesian Plane GIS

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How to store an inventory using hashtables?

- by Harm De Weirdt

Hello everyone. For an assignment in collego we have to make a script in Perl that allows us to manage an inventory for an e-store. (The example given was Amazon) Users can make orders in a fully text-based environment and the inventory must be updated when an order is completed. Every item in the inventory has 3 to 4 attributes: a product code, a title, a price and for some an amount (MP3's for example do not have this attribute) Since this is my first encounter with Perl, i don't really know how to start. My main problem is how i should "implement" the inventory in the program. One of the functions of the program is searching trough the titles. Another is to make an order, where the user should give a product code. My first idea was a hashtable with the productcode as key. But if i wanted to search in the titles that could be a problem because of this: the hashkey would be something like DVD-123, the information belonging to that key could be "The Green Mask 12" (without the ") where the 12 indicates how many of this DVD are currently in stock. So i'd have to find a way to ignore the 12 in the end. Another solution was to use the title as Hashkey, but that would prove cumbersome too I think. Is there a way to make a hashtable with 2 key's, and when I give only one it returns an array with the other values? (Including the other key and the other information) That way I could use another key depending on what info I need from my inventory. We have to read the default inventory from a txt file looking like this: MP3-72|Lady Gaga - Kiss and Run (Fear of Commitment Monster)|0.99 CD-400|Kings of Leon - Only By The Night|14.50|2 MP3-401|Kings of Leon - Closer|0.85 DVD-144|Live Free or Die Hard|14.99|2 SOFT-864|Windows Vista|49.95 Any help would be appreciated very much :) PS: I am sorry for my bad grammar, English isn't my native language.

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PHP webservice for c# application

- by user293995

Hi, I want to create a php webservice server to be used from a C# application. I want to have a library who autogenerate wsdl file for easy management (That's the reason why I choosed NuSoap). I tried to use nusoap on PHP5. I have some problems with charset and Content-Type. Visual Studio gives this error : The HTML document does not contain Web service discovery information. Metadata contains a reference that cannot be resolved: 'https://www.xxx.yy'. There is a problem with the XML that was received from the network. See inner exception for more details. The encoding in the declaration 'ISO-8859-1' does not match the encoding of the document 'utf-8'. If the service is defined in the current solution, try building the solution and adding the service reference again. $soap= new soap_server(); $soap-xml_encoding = 'utf-8'; $soap-configureWSDL('Bonjour', 'https://www.xxx.yy'); $soap-wsdl-schemaTargetNamespace = 'http://soapinterop.org/xsd/'; $soap-register('bonjour', array('prenom' = 'xsd:string')); $HTTP_RAW_POST_DATA = file_get_contents("php://input"); $soap-service($HTTP_RAW_POST_DATA); header('Content-Type: application/soap+xml; charset=utf-8'); function bonjour($prenom) { return "Bonjour ".$prenom; } ? Does someone knows how to change that to make it compliant and working ? Thanks

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NSMutableArray Problem - iPhone

- by David Schiefer

Hi, I'm trying to get a UITableView to read it's data from a file. I've attempted it like this: NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *fullFileName = [NSString stringWithFormat:@"%@/entries.plist", documentsDirectory]; self.dataForTable = [[NSMutableArray alloc] initWithContentsOfFile:fullFileName]; This compiles fine, but when saving something to the file in the following snippet, the file is not saved nor anything is written to the array: NSMutableDictionary*userDictionary; userDictionary = [[NSMutableDictionary alloc] init]; [userDictionary setObject:name.text forKey:@"name"]; [userDictionary setObject:email.text forKey:@"email"]; [userDictionary setObject:serial.text forKey:@"serial"]; [userDictionary setObject:notes.text forKey:@"notes"]; [userDictionary setObject:[NSNumber numberWithInt:[licenseType selectedRowInComponent:0]] forKey:@"license_type"]; [userDictionary setObject:[date date] forKey:@"date"]; [userDictionary setObject:[NSNumber numberWithBool:[paymentSwitch isOn]] forKey:@"payment"]; NSString*dirToSaveTo = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]; NSString*fileName = [NSString stringWithFormat:@"%@.plist",name.text]; NSString*saveName = [dirToSaveTo stringByAppendingPathComponent:fileName]; [userDictionary writeToFile:saveName atomically:NO]; NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSString *fullFileName = [NSString stringWithFormat:@"%@/entries.plist", documentsDirectory]; [self.dataForTable addObject:name.text]; NSLog(@"%@",self.dataForTable); [self.dataForTable writeToFile:fullFileName atomically:YES]; The NSLog just returns (null). The *plist file is never written. What am I doing wrong?

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Two questions on ensuring EndInvoke() gets called on a list of IAsyncResult objects

- by RobV

So this question is regarding the .Net IAsyncResult design pattern and the necessity of calling EndInvoke as covered in this question Background I have some code where I'm firing off potentially many asynchronous calls to a particular function and then waiting for all these calls to finish before using EndInvoke() to get back all the results. Question 1 I don't know whether any of the calls has encountered an exception until I call EndInvoke() and in the event that an exception occurs in one of the calls the entire method should fail and the exception gets wrapped into an API specific exception and thrown upwards. So my first question is what's the best way then to ensure that the remainder of the async calls get properly terminated? Is a finally block which calls EndInvoke() on the remainder of the unterminated calls (and ignores any further exceptions) the best way to do this? Question 2 Secondly when I first fire off all my asyc calls I then call WaitHandle.WaitAll() on the array of WaitHandle instances that I've got from my IAsyncResult instances. The method which is firing all these async calls has a timeout to adhere to so I provide this to the WaitAll() method. Then I test whether all the calls have completed, if not then the timeout must have been reached so the method should also fail and throw another API specific exception. So my second question is what should I do in this case? I need to call EndInvoke() to terminate all these async calls before I throw the error but at the same time I don't want the code to get stuck since EndInvoke() is blocking. In theory at least if the WaitAll() call times out then all the async calls should themselves have timed out and thrown exceptions (thus completing the call) since they are also governed by a timeout but this timeout is potentially different from the main timeout

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Hashtable resizing leaks memory

- by thpetrus

I wrote a hashtable and it basically consists of these two structures: typedef struct dictEntry { void *key; void *value; struct dictEntry *next; } dictEntry; typedef struct dict { dictEntry **table; unsigned long size; unsigned long items; } dict; dict.table is a multidimensional array, which contains all the stored key/value pair, which again are a linked list. If half of the hashtable is full, I expand it by doubling the size and rehashing it: dict *_dictRehash(dict *d) { int i; dict *_d; dictEntry *dit; _d = dictCreate(d->size * 2); for (i = 0; i < d->size; i++) { for (dit = d->table[i]; dit != NULL; dit = dit->next) { _dictAddRaw(_d, dit); } } /* FIXME memory leak because the old dict can never be freed */ free(d); // seg fault return _d; } The function above uses the pointers from the old hash table and stores it in the newly created one. When freeing the old dict d a Segmentation Fault occurs. How am I able to free the old hashtable struct without having to allocate the memory for the key/value pairs again?

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Stored procedure woes ... inserting binary ...

- by Wardy

Ok so I have this storedproc in my SQL 2008 database (works in 2005 too / used to) ... CREATE PROCEDURE [dbo].[SetBinaryContent] @Ref nvarchar(50), @Content varbinary(MAX), @ObjectID uniqueidentifier AS BEGIN DELETE ObjectContent WHERE ObjectId = @ObjectID AND Ref = @Ref IF DATALENGTH(@Content) > 5 BEGIN INSERT INTO ObjectContent (Ref,BinaryContent,ObjectId) VALUES (@Ref,@Content,@ObjectId) END UPDATE Objects SET [Status] = 1 WHERE ID = @ObjectID END Relatively simple, I take a byte array in C# and chuck it in @Content i then give it a guid and string for the other params and off we go. ... Great, it used to work ... but it don't anymore ... so erm ... What's wrong with this stored proc? I've stepped through my C# code thinking I screwed up somehow in that but it definately adds the params and gives them the correct values so what would cause the server to just stop executing this storedproc correctly? When called this proc executes but nothing changes in the db ... no new records are added to the ObjectContent table. Weird huh ...

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Doctrine Default Primary Key Problem (Again)

- by 01010011

Hi, Should I change all of my uniquely-named MySQL database primary keys to 'id' to avoid getting errors related to Doctrine's default primary key set in the plugin 'doctrine_pi.php'? To further elaborate, I am getting the following reoccurring error, this time after trying to login to my login page: SQLSTATE[42S22]: Column not found: 1054 Unknown column 'u.book_id' in 'field list'' in... I suspect the problem resides at a MySQL table used for my login, of which has a primary key called id Marc B originally solved an identical problem for me in this post http://stackoverflow.com/questions/2702229/doctrine-codeigniter-mysql-crud-errors when I had the same problem with a different table within the same database. Following his suggestion, I changed the default primary key located at system/application/plugins/doctrine_pi.php from 'id' to 'book_id': <?php // system/application/plugins/doctrine_pi.php ... // set the default primary key to be named 'id', integer, 4 bytes Doctrine_Manager::getInstance()->setAttribute( Doctrine::ATTR_DEFAULT_IDENTIFIER_OPTIONS, array('name' => 'book_id', 'type' => 'integer', 'length' => 4)); and that solved my previous problem. However, my login page stopped working. So what is the safe thing to do? Change all of my primary keys to 'id' (will that solve the problem without causing some other problem I am not aware of). Or should I add some lines of code in doctrine_pi.php?

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Data Structures for Junior Java Developer

- by user1639637

Ok,still learning Arrays. I wrote this code which fills the array named "rand" with random numbers between 0 and 1( exclusive). I want to start learning Complexity. the For loop executes n times (100 times) ,every time it takes O(1) time,so the worse case scenario is O(n),am I right? Also,I used ArrayList to store the 100 elements and I imported "Collections" and used Collections.sort() method to sort the elements. import java.util.Arrays; public class random { public static void main(String args[]) { double[] rand=new double[10]; for(int i=0;i<rand.length;i++) { rand[i]=(double) Math.random(); System.out.println(rand[i]); } Arrays.sort(rand); System.out.println(Arrays.toString(rand)); } } ArrayList: import java.util.ArrayList; import java.util.Collections; public class random { public static void main(String args[]) { ArrayList<Double> MyArrayList=new ArrayList<Double>(); for(int i=0;i<100;i++) { MyArrayList.add(Math.random()); } Collections.sort(MyArrayList); for(int j=0;j<MyArrayList.size();j++) { System.out.println(MyArrayList.get(j)); } } }

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Save Jquery Object without losing its binding

- by Ahmad Satiri

Hi I have object created using jquery where each object has it's own binding. function closeButton(oAny){ var div = create_div(); $(div).attr("id","btn_"+$(oAny).attr("id")); var my_parent = this; $(div).html("<img src='"+ my_parent._base_url +"/assets/images/close.gif'>"); $(div).click(function(){ alert("do some action here"); }); return div; } var MyObject = WindowObject(); var btn = closeButton(MyObject); $(myobject).append(btn); $("body").append(myobject); //at this point button will work as i expected //save to array for future use ObjectCollections[0] = myobject; //remove $(myobject).remove(); $(body).append(ObjectCollections[0]); // at this point button will not work For the first time i can show my object and close button is working as i expected. But if i save myobject to any variable for future use. It will loose its binding. Anybody ever try to do this ? Is there any work around ? or It is definitely a bad idea ? .And thanks for answering my question.

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Systems design question: DB connection management in load-balanced n-tier

- by aoven

I'm wondering about the best approach to designing a DB connection manager for a load-balanced n-tier system. Classic n-tier looks like this: Client -> BusinessServer -> DBServer A load-balancing solution as I see it would then look like this: +--> ... +--+ +--> BusinessServer +--+--> SessionServer --+ Client -> Gateway --+--> BusinessServer +--| +--> DBServer +--> BusinessServer +--+--------------------+ +--> ... +--+ As pictured, the business server component is being load-balanced via multiple instances, and a hardware gateway is distributing the load among them. Session server probably needs to be situated outside the load-balancing array, because it manages state, which mustn't be duplicated. Barring any major errors in design so far, what is the best way to implement DB connection management? I've come up with a couple of options, but there may be others I'm not aware of: Introduce a new Broker component between the DBServer and the other components and let it handle the DB connections. The upside is that all the connections can be managed from a single point, which is very convenient. The downside is that now there is an additional "single point of failure" in the system. Other components must go through it for every request that involves DB in some way, which also makes this a bottleneck. Move the DB connection management into BusinessServer and SessionServer components and let each handle its own DB connections. The upside is that there is no additional "single point of failure" or bottleneck components. The downside is that there is also no control over possible conflicts and deadlocks apart from what DBServer itself can provide. What else can be done? FWIW: Technology is .NET, but none of the vendor-specific stacks are used (e.g. no WCF, MSMQ or the like).

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SQL placeholder in WHERE IN issue, inserted strings fail.

- by Alastair Pitts

As part of my jobs, I need to writes SQL queries to connect to our PI database. To generate a query, I need to pass an array of tags (essentially primary keys), but these have to be inserted as strings. As this will be a modular query and used for multiple tags, a placeholder is being used. The query relies upon the use of the WHERE IN statement, which is where the placeholder is, like below: SELECT SUM(value * 5/1000) as "Hourly Flow [kL]" from piarchive..pitotal WHERE tag IN (?) AND time between ? and ? and timestep = '1d' and calcbasis = 'Eventweighted' and value <> '' The issue is the format in which the tags are to be passed in as. If I add them directly into the query (for testing), they go in the format (these are example numbers): '000000012','00000032','005050236','4560236' and the query looks like: SELECT SUM(value * 5/1000) as "Hourly Flow [kL]" from piarchive..pitotal WHERE tag IN ('000000012','00000032','005050236','4560236') AND time between ? and ? and timestep = '1d' and calcbasis = 'Eventweighted' and value <> '' which works. If I try and add the same tags into the placeholder, the query fails. If I only add 1 tag, with no quotes (using the placeholder), the query works. Why is this happening? Is there anyway around it?

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Prototypal inheritance should save memory, right?

- by Techpriester

Hi Folks, I've been wondering: Using prototypes in JavaScript should be more memory efficient than attaching every member of an object directly to it for the following reasons: The prototype is just one single object. The instances hold only references to their prototype. Versus: Every instance holds a copy of all the members and methods that are defined by the constructor. I started a little experiment with this: var TestObjectFat = function() { this.number = 42; this.text = randomString(1000); } var TestObjectThin = function() { this.number = 42; } TestObjectThin.prototype.text = randomString(1000); randomString(x) just produces a, well, random String of length x. I then instantiated the objects in large quantities like this: var arr = new Array(); for (var i = 0; i < 1000; i++) { arr.push(new TestObjectFat()); // or new TestObjectThin() } ... and checked the memory usage of the browser process (Google Chrome). I know, that's not very exact... However, in both cases the memory usage went up significantly as expected (about 30MB for TestObjectFat), but the prototype variant used not much less memory (about 26MB for TestObjectThin). I also checked: The TestObjectThin instances contain the same string in their "text" property, so they are really using the property of the prototype. Now, I'm not so sure what to think about this. The prototyping doesn't seem to be the big memory saver at all. I know that prototyping is a great idea for many other reasons, but I'm specifically concerned with memory usage here. Any explanations why the prototype variant uses almost the same amount of memory? Am I missing something?

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