time estimation - Page 758

Bitwise operators and converting an int to 2 bytes and back again.

- by aKiwi

first time user, Hi guys! So hopefully someone can help.. My background is php so entering the word of lowend stuff like, char is bytes, which are bits.. which is binary values.. etc is taking some time to get the hang of ;) What im trying to do here is sent some values from an Ardunio board to openFrameWorks (both are c++). What this script currently does (and works well for one sensor i might add) when asked for the data to be sent is.. int value_01 = analogRead(0); // which outputs between 0-1024 unsigned char val1; unsigned char val2; //some Complicated bitshift operation val1 = value_01 &0xFF; val2 = (value_01 >> 8) &0xFF; //send both bytes Serial.print(val1, BYTE); Serial.print(val2, BYTE); Apparently this is the most reliable way of getting the data across.. So now that it is send via serial port, the bytes are added to a char string and converted back by.. int num = ( (unsigned char)bytesReadString[1] << 8 | (unsigned char)bytesReadString[0] ); So to recap, im trying to get 4 sensors worth of data (which im assuming will be 8 of those serialprints?) and to have int num_01 - num_04... at the end of it all. Im assuming this (as with most things) might be quite easy for someone with experience in these concepts.. Any help would be greatly appreciated. Thanks

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SQLite Databases and Grid Hosting

- by jocull

I'm considering moving my site from a GoDaddy shared hosting account to a Media Temple grid hosting account in anticipation of traffic. However, I first have some concerns with the grid hosting setup. My site stores a large personal set of data on a per-user basis (possibly 3-4MB per user). At this rate I was worried about blowing over a 1GB MySQL limit in no time. To deal with this I created distributed SQLite databases per user to store large data objects. It's worked wonderfully so far. SQLite is super fast and simple. I know that reading from and writing to files is different in a Grid Hosting environment. I need to know if this setup is going to cause serious problems. These databases are not (and will not be) highly trafficked. They are personal to the user and will only be touched maybe two locations at the same time (one updating the data hourly at the most, and one or more reading on demand). I'd like to keep this setup as getting additional space (beyond 4GB) on a MySQL database seems to be a real trouble point. Will Grid Hosting cause me serious problems? Thanks.

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Got Hacked. Want to understand how.

- by gaoshan88

Someone has, for the second time, appended a chunk of javascript to a site I help run. This javascript hijacks Google adsense, inserting their own account number, and sticking ads all over. The code is always appended, always in one specific directory (one used by a third party ad program), affects a number of files in a number of directories inside this one ad dir (20 or so) and is inserted at roughly the same overnight time. The adsense account belongs to a Chinese website (located in a town not an hour from where I will be in China next month. Maybe I should go bust heads... kidding, sort of), btw. So, how could they append text to these files? Is it related to the permissions set on the files (ranging from 755 to 644)? To the webserver user (it's on MediaTemple so it should be secure, yes?)? I mean, if you have a file that has permissions set to 777 I still can't just add code to it at will... how might they be doing this?

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Parsing data with Clojure, interval problem.

- by Andrea Di Persio

Hello! I'm writing a little parser in clojure for learning purpose. basically is a TSV file parser that need to be put in a database, but I added a complication. The complication itself is that in the same file there are more intervals. The file look like this: ###andreadipersio 2010-03-19 16:10:00### USER COMM PID PPID %CPU %MEM TIME root launchd 1 0 0.0 0.0 2:46.97 root DirectoryService 11 1 0.0 0.2 0:34.59 root notifyd 12 1 0.0 0.0 0:20.83 root diskarbitrationd 13 1 0.0 0.0 0:02.84` .... ###andreadipersio 2010-03-19 16:20:00### USER COMM PID PPID %CPU %MEM TIME root launchd 1 0 0.0 0.0 2:46.97 root DirectoryService 11 1 0.0 0.2 0:34.59 root notifyd 12 1 0.0 0.0 0:20.83 root diskarbitrationd 13 1 0.0 0.0 0:02.84 I ended up with this code: (defn is-header? "Return true if a line is header" [line] (> (count (re-find #"^\#{3}" line)) 0)) (defn extract-fields "Return regex matches" [line pattern] (rest (re-find pattern line))) (defn process-lines [lines] (map process-line lines)) (defn process-line [line] (if (is-header? line) (extract-fields line header-pattern)) (extract-fields line data-pattern)) My idea is that in 'process-line' interval need to be merged with data so I have something like this: ('andreadipersio', '2010-03-19', '16:10:00', 'root', 'launchd', 1, 0, 0.0, 0.0, '2:46.97') for every row till the next interval, but I can't figure how to make this happen. I tried with something like this: (def process-line [line] (if is-header? line) (def header-data (extract-fields line header-pattern))) (cons header-data (extract-fields line data-pattern))) But this doesn't work as excepted. Any hints? Thanks!

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What if a large number of objects are passed to my SwingWorker.process() method?

- by Trejkaz

I just found an interesting situation. Suppose you have some SwingWorker (I've made this one vaguely reminiscent of my own): public class AddressTreeBuildingWorker extends SwingWorker<Void, NodePair> { private DefaultTreeModel model; public AddressTreeBuildingWorker(DefaultTreeModel model) { } @Override protected Void doInBackground() { // Omitted; performs variable processing to build a tree of address nodes. } @Override protected void process(List<NodePair> chunks) { for (NodePair pair : chunks) { // Actually the real thing inserts in order. model.insertNodeInto(parent, child, parent.getChildCount()); } } private static class NodePair { private final DefaultMutableTreeNode parent; private final DefaultMutableTreeNode child; private NodePair(DefaultMutableTreeNode parent, DefaultMutableTreeNode child) { this.parent = parent; this.child = child; } } } If the work done in the background is significant then things work well - process() is called with relatively small lists of objects and everything is happy. Problem is, if the work done in the background is suddenly insignificant for whatever reason, process() receives a huge list of objects (I have seen 1,000,000, for instance) and by the time you process each object, you have spent 20 seconds on the Event Dispatch Thread, exactly what SwingWorker was designed to avoid. In case it isn't clear, both of these occur on the same SwingWorker class for me - it depends on the input data, and the type of processing the caller wanted. Is there a proper way to handle this? Obviously I can intentionally delay or yield the background processing thread so that a smaller number might arrive each time, but this doesn't feel like the right solution to me.

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Possibility of a custom Contacts field with a set list of values and Contacts lookup performance

- by areyling

I'm pretty sure it's not viable to do what I'd like to based on some initial research, but I figured it couldn't hurt to ask the community of experts here in case someone knows a way. I'd like to create a custom field for contacts that the user is able to edit from the main Contacts app; however, the user should only be allowed to select from a list of four specific values. A short list of string values would be ideal, but an int with a min/max range would suffice. I'm interested in knowing if it's possible either way, but also wondering if it make sense to go this route performance wise. More specifically, would it be better to look up a contact (based on a phone number) each time a call or SMS message is received or better to store my own set of data (consisting of name, numbers, and the custom field) and just syncing contact info in a thread every so often? Or syncing contacts the first time the app is run and then registering for changes using ContentObserver? Here is a similar question with an answer that explains how to add a custom field to a contact. Thanks in advance.

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MYSQL JOIN WHERE ISSUES - need some kind of if condition

- by Breezer

Hi Well this will be hard to explain but ill do my best The thing is i have 4 tables all with a specific column to relate to eachother. 1 table with users(agent_users) , 1 with working hours(agent_pers), 1 with sold items(agent_stat),1 with project(agent_pro) the user and the project table is irrelevant in the issue at hand but to give you a better understanding why certain tables is included in my query i decided to still mention them =) The thing is that I use 2 pages to insert data to the working hour and the sold items during that time tables, then i have a third page to summarize everything for current month, the query for that is as following: SELECT *, SUM(sv_p_kom),SUM(sv_p_gick),SUM(sv_p_lunch) FROM (( agent_users LEFT JOIN agent_pers ON agent_users.sv_aid = agent_pers.sv_p_uid) LEFT JOIN agent_stat ON agent_pers.sv_p_uid = agent_stat.sv_s_uid) LEFT JOIN agent_pro ON agent_pers.sv_p_pid=agent_pro.p_id WHERE MONTH(agent_pers.sv_p_datum) =7 GROUP BY sv_aname so the problem is now that i dont want sold items from previous months to get included in the data received, i know i could solve that by simple adding in the WHERE part MONTH(agent_stat.sv_s_datum) =7 but then if no items been sold that month no data at all will show up not the time or anything. Any aid on how i could solve this is greatly appreciated. if there's something that's not so clear dont hesitate to ask and ill try my best to answer. after all my english isn't the best out there :P regards breezer

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NSCollectionView: Can the same object not be in the array more than once or is this a bug?

- by Sean

I may be doing this all wrong, but I thought I was on the right track until I hit this little snag. Basically I was putting together a toy using NSCollectionView and trying to understand how to hook that all up using IB. I have a button which will add a couple of strings to the NSArrayController: The first time I press this button, my strings appear in the collection view as expected: The second time I press the button, the views scroll down and room is made - but the items don't appear to get added. I just see blank space: The button is implemented as follows (controller is a pointer to the NSArrayController I added in IB): - (IBAction)addStuff:(id)control { [controller addObjects:[NSArray arrayWithObjects:@"String 1",@"String 2",@"String 3",nil]]; } I'm not sure what I'm doing wrong. Rather than try to explain all the connections/binds/etc, if you need more info, I'd be grateful if you could just take a quick look at the toy project itself. UPDATE: After more experimentation as suggested by James Williams, it seems the problem stems from having multiple objects with the same memory address in the array. This confuses either NSArrayController or NSCollectionView (not sure which). Changing my addStuff: to this resulted in the behavior I originally expected: [controller addObjects:[NSArray arrayWithObjects:[NSMutableString stringWithString:@"String 1"],[NSMutableString stringWithString:@"String 2"],[NSMutableString stringWithString:@"String 3"],nil]]; So the question now, I guess, is if this is a bug I should report to Apple or if this is intended/documented behavior and I just missed it?

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Blackberry Keyboard Lock timeout

- by Vernon

I want this blackberry 9700 to "fully lock" as soon as I click the icon for the "Keyboard Lock" application. Currently I have to wait 5 to 7 seconds for the screen to go dark after each time I click the "Keyboard Lock" icon. During that time if something touches the touch pad, then the 5-7 second timer resets and you have to wait another 5 to 7 seconds for the screen to go dark and "fully lock" After it finally goes dark, touching the touch pad does not reset the timer. At that point it is "fully locked" and requires a key to be pressed. How can I get it to "fully lock" as soon as the lock icon is clicked? I want the screen to go dark immediately, and for it to require a key press to request an unlock. I have tried Options - Screen/Keyboard - Backlight Timeout ... etc ... none of that reduces the timeout for the "Keyboard Lock" application. And there does not seem to be an option screen for the "Keyboard Lock" application, that I can find. NOTE: This is occurring with BlackBerry 9700 v5.0.0.330 (Platform 5.1.0.91)

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How to use Java on Google App Engine without exceeding minute quotas?

- by Geo

A very simple java code inside a doGet() servlet is getting more than a second of cpu time on GAE. I have read some quota related documentation and apparently I am not doing anything wrong. //Request the user Agent info String userAgent = req.getHeader("User-Agent"); I wanted to know what was using the CPU the most, I use a google help recommendation. //The two lines below will get the CPU before requesting User-Agent Information QuotaService qs = QuotaServiceFactory.getQuotaService(); long start = qs.getCpuTimeInMegaCycles(); //Request the user Agent info String userAgent = req.getHeader("User-Agent"); //The three lines below will get the CPU after requesting User-Agent Information // and informed it to the application log. long end = qs.getCpuTimeInMegaCycles(); double cpuSeconds = qs.convertMegacyclesToCpuSeconds(end - start); log.warning("CPU Seconds on geting User Agent: " + cpuSeconds); The only thing that the code above tells me is that inspecting the header will use more than a second (1000ms) of cpu time, which for Google is a warning on the log panel. That seems to be a very simple request and still is using more than a second of cpu. What I am missing?

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Facing error in apple multitasking code

- by user366584

Actually I am working for multitasking and facing error please assist me, as I need to work on background application and also in foreground application - (void)applicationDidEnterBackground:(UIApplication *)application { UIApplication* app = [UIApplication sharedApplication]; // Request permission to run in the background. Provide an // expiration handler in case the task runs long. NSAssert(bgTask == UIBackgroundTaskInvalid, nil); bgTask = [app beginBackgroundTaskWithExpirationHandler:^{ // Synchronize the cleanup call on the main thread in case // the task actually finishes at around the same time. dispatch_async(dispatch_get_main_queue(), ^{ if (bgTask != UIBackgroundTaskInvalid) { [app endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; } }); }]; // Start the long-running task and return immediately. dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ // Do the work associated with the task. // Synchronize the cleanup call on the main thread in case // the expiration handler is fired at the same time. dispatch_async(dispatch_get_main_queue(), ^{ if (bgTask != UIBackgroundTaskInvalid) { [app endBackgroundTask:bgTask]; bgTask = UIBackgroundTaskInvalid; } }); }); }

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Question about memory allocation when initializing char arrays in C/C++.

- by Carlos Nunez

Before anything, I apologize if this question has been asked before. I am programming a simple packet sniffer for a class project. For a little while, I ran into the issue where the source and destination of a packet appeared to be the same. For example, the source and destination of an Ethernet frame would be the same MAC address all of the time. I custom-made ether_ntoa(char *) because Windows does not seem to have ethernet.h like Linux does. Code snippet is below: char *ether_ntoa(u_char etheraddr[ETHER_ADDR_LEN]) { int i, j; char eout[32]; for(i = 0, j = 0; i < 5; i++) { eout[j++] = etheraddr[i] >> 4; eout[j++] = etheraddr[i] & 0xF; eout[j++] = ':'; } eout[j++] = etheraddr[i] >> 4; eout[j++] = etheraddr[i] & 0xF; eout[j++] = '\0'; for(i = 0; i < 17; i++) { if(eout[i] < 10) eout[i] += 0x30; else if(eout[i] < 16) eout[i] += 0x57; } return(eout); } I solved the problem by using malloc() to have the compiler assign memory (i.e. instead of char eout[32], I used char * eout; eout = (char *) malloc (32);). However, I thought that the compiler assigned different memory locations when one sized a char-array at compile time. Is this incorrect? Thanks! Carlos Nunez

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ps: Clean way to only get parent processes?

- by shkschneider

I use ps ef and ps rf a lot. Here is a sample output for ps rf: PID TTY STAT TIME COMMAND 3476 pts/0 S 0:00 su ... 3477 pts/0 S 0:02 \_ bash 8062 pts/0 T 1:16 \_ emacs -nw ... 15733 pts/0 R+ 0:00 \_ ps xf 15237 ? S 0:00 uwsgi ... 15293 ? S 0:00 \_ uwsgi ... 15294 ? S 0:00 \_ uwsgi ... And today I needed to retrieve only the master process of uwsgi in a script (so I want only 15237 but not 15293 nor 15294). As of today, I tried some ps rf | grep -v ' \\_ '... but I would like a cleaner way. I also came accross another solution from unix.com's forums: ps xf | sed '1d' | while read pid tty stat time command ; do [ -n "$(echo $command | egrep '^uwsgi')" ] && echo $pid ; done But still a lot of pipes and ugly tricks. Is there really no ps option or cleaner tricks (maybe using awk) to accomplish that?

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array of structures, or structure of arrays?

- by Jason S

Hmmm. I have a table which is an array of structures I need to store in Java. The naive don't-worry-about-memory approach says do this: public class Record { final private int field1; final private int field2; final private long field3; /* constructor & accessors here */ } List<Record> records = new ArrayList<Record>(); If I end up using a large number ( 106 ) of records, where individual records are accessed occasionally, one at a time, how would I figure out how the preceding approach (an ArrayList) would compare with an optimized approach for storage costs: public class OptimizedRecordStore { final private int[] field1; final private int[] field2; final private long[] field3; Record getRecord(int i) { return new Record(field1[i],field2[i],field3[i]); } /* constructor and other accessors & methods */ } edit: assume the # of records is something that is changed infrequently or never I'm probably not going to use the OptimizedRecordStore approach, but I want to understand the storage cost issue so I can make that decision with confidence. obviously if I add/change the # of records in the OptimizedRecordStore approach above, I either have to replace the whole object with a new one, or remove the "final" keyword. kd304 brings up a good point that was in the back of my mind. In other situations similar to this, I need column access on the records, e.g. if field1 and field2 are "time" and "position", and it's important for me to get those values as an array for use with MATLAB, so I can graph/analyze them efficiently.

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PHP Socket Server vs node.js: Web Chat

- by Eliasdx

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

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NSTimer Reset Not Working

- by user355900

hi, i have a nstimer and it works perfectly counting down from 2:00 but when i hit the reset button it does not work it just stops the timer and when i press start again it will carry on with the timer as if it had never been stopped. Here is my code `@implementation TimerAppDelegate @synthesize window; (void)applicationDidFinishLaunching:(UIApplication *)application { timerLabel.text = @"2:00"; seconds = 120; // Override point for customization after application launch [window makeKeyAndVisible]; } (void)viewDidLoad { [timer invalidate]; } (void)countDownOneSecond { seconds--; int currentTime = [timerLabel.text intValue]; int newTime = currentTime - 1; int displaySeconds = !(seconds % 60) ? 0 : seconds < 60 ? seconds : seconds - 60; int displayMinutes = floor(seconds / 60); NSString *time = [NSString stringWithFormat:@"%d:%@%d", displayMinutes, [[NSString stringWithFormat:@"%d", displaySeconds] length] == 1 ? @"0" : @"", displaySeconds ]; timerLabel.text = time; if(seconds == 0) { [timer invalidate]; } } (void)startOrStopTimer { if(timerIsRunning){ [timer invalidate]; [startOrStopButton setTitle:@"Start" forState:UIControlStateNormal]; } else { timer = [[NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(countDownOneSecond) userInfo:nil repeats:YES] retain]; [startOrStopButton setTitle:@"Stop" forState:UIControlStateNormal]; } timerIsRunning = !timerIsRunning; } (void)resetTimer { [timer invalidate]; [startOrStopButton setTitle:@"Start" forState:UIControlStateNormal]; [timer invalidate]; timerLabel.text = @"2:00"; } (void)dealloc { [window release]; [super dealloc]; } @end` thanks

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Checking for nil in view in Ruby on Rails

- by seaneshbaugh

I've been working with Rails for a while now and one thing I find myself constantly doing is checking to see if some attribute or object is nil in my view code before I display it. I'm starting to wonder if this is always the best idea. My rationale so far has been that since my application(s) rely on user input unexpected things can occur. If I've learned one thing from programming in general it's that users inputting things the programmer didn't think of is one of the biggest sources of run-time errors. By checking for nil values I'm hoping to sidestep that and have my views gracefully handle the problem. The thing is though I typically for various reasons have similar nil or invalid value checks in either my model or controller code. I wouldn't call it code duplication in the strictest sense, but it just doesn't seem very DRY. If I've already checked for nil objects in my controller is it okay if my view just assumes the object truly isn't nil? For attributes that can be nil that are displayed it makes sense to me to check every time, but for the objects themselves I'm not sure what is the best practice. Here's a simplified, but typical example of what I'm talking about: controller code def show @item = Item.find_by_id(params[:id]) @folders = Folder.find(:all, :order => 'display_order') if @item == nil or @item.folder == nil redirect_to(root_url) and return end end view code <% if @item != nil %> display the item's attributes here <% if @item.folder != nil %> <%= link_to @item.folder.name, folder_path(@item.folder) %> <% end %> <% else %> Oops! Looks like something went horribly wrong! <% end %> Is this a good idea or is it just silly?

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MySQL query optimization - distinct, order by and limit

- by Manuel Darveau

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Unable to turn off notice errors in PHP 5.3.2

- by knkk

Hi everyone, I recently migrated to PHP 5.3.2, and realized that I am unable to turn off notice errors in my site now. I went to php.ini, and in these lines: ; Common Values: ; E_ALL & ~E_NOTICE (Show all errors, except for notices and coding standards warnings.) ; E_ALL & ~E_NOTICE | E_STRICT (Show all errors, except for notices) ; E_COMPILE_ERROR|E_RECOVERABLE_ERROR|E_ERROR|E_CORE_ERROR (Show only errors) ; E_ALL | E_STRICT (Show all errors, warnings and notices including coding standards.) ; Default Value: E_ALL & ~E_NOTICE ; Development Value: E_ALL | E_STRICT ; Production Value: E_ALL & ~E_DEPRECATED ; http://php.net/error-reporting error_reporting = E_ALL & ~E_NOTICE ...I've tried setting everything (and I restart apache each time), but I am unable to get rid of notices. The only way I'm able to get rid of notice errors is by setting : display_errors = Off That is, of course, not something I can do since I need to see errors to fix them, and I would like to see errors on the webpage that I am coding rather than log them somewhere. Can someone help? Is this a bug in PHP 5.3.2 or something I am doing wrong? Thank you very much for your time! P. S. Also, would anyone know how I can get PHP 5.3.2 to support the .php3 extension?

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what to do when you are completely burnt out from working on a project ?

- by dfafa

so i started this SaaS project around July 2009, was expecting to finish it in 2 months. i ended up working on it for about 4 months straight, spending about 6~12 hours nearly everyday. then one day i just couldn't bare to look at the code. it seems like my efforts are being sucked in by some black hole. i would need to put lot of work to make incremental changes. i felt burnt out in December....and now it's May. i am working on the project maybe for about 10 hours every 2 weeks...i am not getting much done. it seems like it will never be perfect. the more i code, more problems and bugs to fix, its absolutely sickening. so what should i do now ? i have invested all of my available time and money, i've shut off all social connections and basically have been spending most of my time in my room working on my project alone. i feel consumed by this project i created ironically, to make my life easier.

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Create new or update existing entity at one go with JPA

- by Alex R

A have a JPA entity that has timestamp field and is distinguished by a complex identifier field. What I need is to update timestamp in an entity that has already been stored, otherwise create and store new entity with the current timestamp. As it turns out the task is not as simple as it seems from the first sight. The problem is that in concurrent environment I get nasty "Unique index or primary key violation" exception. Here's my code: // Load existing entity, if any. Entity e = entityManager.find(Entity.class, id); if (e == null) { // Could not find entity with the specified id in the database, so create new one. e = entityManager.merge(new Entity(id)); } // Set current time... e.setTimestamp(new Date()); // ...and finally save entity. entityManager.flush(); Please note that in this example entity identifier is not generated on insert, it is known in advance. When two or more of threads run this block of code in parallel, they may simultaneously get null from entityManager.find(Entity.class, id) method call, so they will attempt to save two or more entities at the same time, with the same identifier resulting in error. I think that there are few solutions to the problem. Sure I could synchronize this code block with a global lock to prevent concurrent access to the database, but would it be the most efficient way? Some databases support very handy MERGE statement that updates existing or creates new row if none exists. But I doubt that OpenJPA (JPA implementation of my choice) supports it. Event if JPA does not support SQL MERGE, I can always fall back to plain old JDBC and do whatever I want with the database. But I don't want to leave comfortable API and mess with hairy JDBC+SQL combination. There is a magic trick to fix it using standard JPA API only, but I don't know it yet. Please help.

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Why is debugging better in an IDE?

- by Bill Karwin

I've been a software developer for over twenty years, programming in C, Perl, SQL, Java, PHP, JavaScript, and recently Python. I've never had a problem I could not debug using some careful thought, and well-placed debugging print statements. I respect that many people say that my techniques are primitive, and using a real debugger in an IDE is much better. Yet from my observation, IDE users don't appear to debug faster or more successfully than I can, using my stone knives and bear skins. I'm sincerely open to learning the right tools, I've just never been shown a compelling advantage to using visual debuggers. Moreover, I have never read a tutorial or book that showed how to debug effectively using an IDE, beyond the basics of how to set breakpoints and display the contents of variables. What am I missing? What makes IDE debugging tools so much more effective than thoughtful use of diagnostic print statements? Can you suggest resources (tutorials, books, screencasts) that show the finer techniques of IDE debugging? Sweet answers! Thanks much to everyone for taking the time. Very illuminating. I voted up many, and voted none down. Some notable points: Debuggers can help me do ad hoc inspection or alteration of variables, code, or any other aspect of the runtime environment, whereas manual debugging requires me to stop, edit, and re-execute the application (possibly requiring recompilation). Debuggers can attach to a running process or use a crash dump, whereas with manual debugging, "steps to reproduce" a defect are necessary. Debuggers can display complex data structures, multi-threaded environments, or full runtime stacks easily and in a more readable manner. Debuggers offer many ways to reduce the time and repetitive work to do almost any debugging tasks. Visual debuggers and console debuggers are both useful, and have many features in common. A visual debugger integrated into an IDE also gives you convenient access to smart editing and all the other features of the IDE, in a single integrated development environment (hence the name).

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Where do I put javaassist code?

- by DutrowLLC

I have an application running on google app engine. I'm using restlets and I have a couple of layers set up including the restlet layer, the model layer, the business layer, and the data layer. I'm attempting to use javaassist to modify some classes, but I'm unsure where to actually put the code. I tried to put the code in the static initialization block: public class Person { String firstName; String getFirstName(){return null;} static{ ClassPool pool = ClassPool.getDefault(); try { CtClass CtPerson = pool.get("Person"); CtMethod CtGetFirstName = CtPerson.getDeclaredMethod("GetFirstName"); CtGetFirstName.setBody("return firstName;"); CtPerson.toClass(); } catch (Exception e) { e.printStackTrace(); } } } ...but that resulted in this error: javassist.CannotCompileException:.....attempted duplicate class definition...". I guess it makes sense that I can't edit the class file in the middle of its generation. I know the code works because I was able to run it correctly by simply putting it in a location that would run when I sent the program a command. (accessed a Restlet resource). The code ran fine if an instance of the class had not already been instantiated, however once I instantiated an instance of the affected class, the javaassist code failed. I assume I need to put this code somewhere that it will only run either: once after the program starts, directly before a class is instantiated for the first time, or even better, during compile time.

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jquery append 'x' number images elements applying 'x' to src and class

- by Yusaf

I have a directory with 590 pictures and my issue is being able to pull images using jquery alone from that directory and appending them which i have found out can not be done alone using jquery/javascript. alternatively i have renamed the pictures 1.jpg,2.jpg ... 590.jpg . how using jquery can i append 590 images to a div leaving me with the number of the appended element applied to the src being 'lq'+numberofappended+'.jpg' and class being 'image-'+numberofappended as a result leaving me with the below <div class="imagecontainer"> <img src="lq/1.jpg" class="image-1"/> <img src="lq/2.jpg" class="image-2"/> <img src="lq/3.jpg" class="image-3"/> ... <img src="lq/590.jpg" class="image-590"/> </div> if what I have will be too extensive can i append 50 images at a time and apply a jquery pagination loading another 50 each time i reach the end of the page. I personally know how to use append in jquery but I don't know how to individually append an image and depending on which append number it is applying it to the src and class.

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How do I interact with a Perl object that has a hash attribute?

- by brydgesk

I have a class with several variables, one of which is a hash (_runs): sub new { my ($class, $name) = @_; my $self = { _name => $name, ... _runs => (), _times => [], ... }; bless ($self, $class); return $self; } Now, all I'm trying to do is create an accessor/mutator, as well as another subroutine that pushes new data into the hash. But I'm having a hell of a time getting all the referencing/dereferencing/$self calls working together. I've about burned my eyes out with "Can't use string ("blah") as a HASH ref etc etc" errors. For the accessor, what is 'best practice' for returning hashes? Which one of these options should I be using (if any)?: return $self->{_runs}; return %{ $self->{_runs} }; return \$self->{_runs}; Further, when I'm using the hash within other subroutines in the class, what syntax do I use to copy it? my @runs = $self->{_runs}; my @runs = %{ $self->{_runs} }; my @runs = $%{ $self->{_runs} }; my @runs = $$self->{_runs}; Same goes for iterating over the keys: foreach my $dt (keys $self->{_runs}) foreach my $dt (keys %{ $self->{_runs} }) And how about actually adding the data? $self->{_runs}{$dt} = $duration; %{ $self->{_runs} }{$dt} = $duration; $$self->{_runs}{$dt} = $duration; You get the point. I've been reading articles about using classes, and articles about referencing and dereferencing, but I can't seem to get my brain to combine the knowledge and use both at the same time. I got my _times array working finally, but mimicking my array syntax over to hashes didn't work.

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