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• iPhone "multi-threading" question

  - by MrDatabase

  I have a simple iPhone game consisting of two "threads": the main game loop where all updating and rendering happen 30 times per second (NSTimer)... and the "thread" that calls the accelerometer delegate 100 times per second. I have a variable "xPosition" that's updated in the accelerometer delegate function and used in the game loop. Is there a possibility of the two "threads" trying to use xPosition at the same time (hence causing a crash or some other problem). If so how can I fix this w/ minimal impact to the game's performance? I've been using this set-up for many months of development and incremental testing and I've never run into any problems. Cheers!

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• Apache crashes after installing mysqli

  - by Marco P.

  System: Apache 2.2 running on Windows 2008 Server with PHP 5.2.17 VC6 Thread-Safe as a Module and MySQL 5.5.17 - all working fine. After installing mysqli using the php package, Apache won't start anymore. There is no error message in the log. What I have tried: Make sure Windows PATH points to libmysql.dll: Yes, done. Make sure extension_dir points to the right point: Yes. Other extensions load fine. Try without mysqli: Yes, Apache loads fine then. Try without mysql: Yes, does not help. Test mysql itself: Restarts server! Overwrite libmysql: Yes, does not help. It seems to me that there is some general problem with MySql, but the DB server seems to be running fine. I'm really out of ideas of things I could try, so I'm desperate for any hints or tricks.

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• [Java]Queue in while loop, cannot modify the value?

  - by javaLearner.java

  This is my code: Iterator it = queue.iterator(); while(it.hasNext()){ random = randNumber(1,2); if(random == 1){ queue.poll(); } else { queue.add("new"); queue.poll(); } } It gives me: Exception in thread "test" java.util.ConcurrentModificationException at java.util.LinkedList$ListItr.checkForComodification(LinkedList.java:761) at java.util.LinkedList$ListItr.next(LinkedList.java:696) Edit @Jon Skeet: What I want to do is: I have a queue list in, let say the size is 10, lets say: a,b,c,d ... j Generate a number between 1 and 2. if 1, pull (remove the top element) else if 2 add new element I will stop the loop until I added 3 new elements

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• Easy Threading in WPF

  - by Sandeep Bansal

  Hi everyone, I've been reading a lot about threading in C#, WPF and Silverlight but can't get it to work. My main problem is I have the _load (_Initialized) action and it has a lot of object creation and along with that I have timers working doing different things, this causes the startup time of the program to be very slow and obviously causes the UI to hang and it isn't a good thing for deploying to a lot of users. My timers change values of labels and textfields but having them do that on another thread is an obvious no go. So can someone give me some examples on how to achieve what I need to do? Thanks

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• .NET web service call slower when performed asynchronously

  - by joelt

  I have an ASP.NET site, and some pages need to call a web service. I used Visual Studio's "Add Web Reference" to auto-generate classes and methods for the web service. When I call the service synchronously, i.e. objService.MethodName("param1"), a call might take a second or so. When I call it asynchronously, i.e., objService.BeginMethodName("param1", AddressOf MyCallback, Nothing), it typically takes about 6 seconds. When debugging, it appears that the bulk of the time is spent waiting between the completion of the BeginMethodName call and the beginning of MyCallback. Does the thread switching really incur that much overhead? Is there another reason for this?

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• Portable Socket programming in C/C++ possible?

  - by questions

  I am thinking of creating a multi-platform portable C++ server-client application. Is it even possible while using only standard libraries? If no, what other libraries are there? Are there any improvements in this direction in C++11x? Like for threads, now we have std::threads. To make it more clear.. I want something like boost::thread, which provides multiplatform portable multithreading, for networking. And why C++ doesn't have libraries(standard) for such basic things like networking?

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• Android: how to have app talk to a web page, ie send gps location

  - by Ted pottel

  I'm trying to write a app, where a webpage will have a button that when press will give the GPS location of the phone. I was going to have the android app create a thread that waits on a scket connection. The issue is that 1. Getting the ip addrs of the phone 2. I was told this would really drain the battery I was also thinking about having the phone send the gps location to a webserver like evrry 10 seconds. This sort of seams like a waste of bandwidth. Is there a good way to do this?

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• Delay in for loop while playing mp3 file C#

  - by daniyalahmad

  I want to give delay in for loop, While in for loop there is mp3 file is playing. What I actually want to do, that every clip plays after 2 sec. There are total 10 clips. Here is my code for (int i=1; i < 10; i++) { System.Threading.Thread.Sleep(1000); WMPLib.WindowsMediaPlayer wplayer = new WMPLib.WindowsMediaPlayer(); wplayer.URL = @"D:\Project C#\A-Z\" + i + ".mp3"; }

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• Should I use multiple threads in this situation? [Ruby]

  - by mr popo

  I'm opening multiple files and processing them, one line at a time. The files contain tokens separating the data, such that sometimes the processing of one file may have to wait for others to catch up to that same token. I was doing this initially with only one thread and an array indicating with true/false if the file should be read in the current iteration or if it should wait for some of the others to catch up. Would using threads make this simpler? More efficient? Does Ruby have a mechanism for this?

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• Creating a textarea with auto-resize

  - by DisgruntledGoat

  There was another thread about this, which I've tried. But there is one problem: the textarea doesn't shrink if you delete the content. I can't find any way to shrink it to the correct size - the clientHeight value comes back as the full size of the textarea, not its contents. The code from that page is below. I'd appreciate any help or pointers. function FitToContent(id, maxHeight) { var text = id && id.style ? id : document.getElementById(id); if ( !text ) return; var adjustedHeight = text.clientHeight; if ( !maxHeight || maxHeight > adjustedHeight ) { adjustedHeight = Math.max(text.scrollHeight, adjustedHeight); if ( maxHeight ) adjustedHeight = Math.min(maxHeight, adjustedHeight); if ( adjustedHeight > text.clientHeight ) text.style.height = adjustedHeight + "px"; } } window.onload = function() { document.getElementById("ta").onkeyup = function() { FitToContent( this, 500 ) }; }

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• Linux How to print all the files with the same prefix after searching for them?

  - by Alyx

  I need to search through a directory which contains many sub directories, each which contain files. The files read as follows question1234_01, where 1234 are random digits and the suffix _01 is the number of messages that contain the prefix, meaning they are apart of the same continuing thread. find . -name 'quest*' | cut -d_ -f1 | awk '{print $1}' | uniq -c | sort -n example output: 1 quest1234 10 quest1523 This searches for all the files then sorts them in order. What I want to do is print all the files which end up having the most occurrences, in my example the one with 10 matches. So it should only output quest1523_01 - 11

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• Android FTP seek Bar issue

  - by Androi Developer

  I am trying to Upload & Download file to server using FTP and Download File using HTTP i am able to do this, my problem is when i am trying to show seek bar with Upload status of file using ftp then it's not showing. In this attached image Using HTTP it's showing seekbar with Network spped like this i need to display seek bar & Network sppeed in FTP. Below code i wrote for FTP to upload file into server. Code:-- // Upload System.out.println("upload test is called"); //Toast.makeText(con, "upload FTP test is called", Toast.LENGTH_SHORT).show(); //ContextWrapper context = null; //assetManager= context.getAssets(); assetManager = getResources().getAssets(); input1 = assetManager.open("hello.txt"); final long started = System.currentTimeMillis(); int size = input1.available(); //byte[] buffer = new byte[size]; byte dataByte[] = new byte[1024]; //input1.read(buffer); //String data = "ZK DATA TESTER TEST DATA1sdfsdf"; String data = input1.toString(); System.out.println("dat value is........"+data); final int lenghtOfFile = data.getBytes().length; //final int lenghtOfFile = input1.getBytes().length; System.out.println("length of file....."+lenghtOfFile); ByteArrayInputStream in = new ByteArrayInputStream( data.getBytes()); //toast("Uploading /test.txt"); //Toast.makeText(con,"File Size : " +data.getBytes().length + " bytes",Toast.LENGTH_SHORT).show(); //byte b[] = new byte[1024]; long total = 0; long sleepingTime= 0; System.out.println("started time --"+started); updateUI(status, "Uploading"); while ((count = in.read(dataByte)) != -1) { System.out.println("read value is...."+in.read(dataByte)); while (sleep1) { Thread.sleep(1000); System.out.println("ftp upload is in sleeping mode"); sleepingTime +=1000; } System.out.println("Total count --"+count); total += count; System.out.println("Only Total --"+total); final int progress = (int) ((total * 100) / lenghtOfFile); final long speed = total; //duration = ((System.currentTimeMillis() - started)-sleepingTime) / 1000; boolean result = ObjFtpCon.storeFile("/test.txt", input1); //boolean result = ObjFtpCon.storeFile(map.get("file_address").toString()+"/test.txt", input1); duration = ((System.currentTimeMillis() - started)-sleepingTime) / 1000; /* runOnUiThread(new Runnable() { public void run() { bar.setProgress(progress); // trans.setText("" + progress); //duration = ((System.currentTimeMillis() - started)-sleepingTime) / 1000; //duration = ((System.currentTimeMillis() - started)-sleepingTime) / 1000; //real_time.setText(duration + " secs"); if (duration != 0) { test_avg.setText((((speed / duration)*1000)*0.0078125) + " kbps"); if (pk <= (speed / duration) / 1024) { pk = (speed / duration) / 1024; } if (pk <= ((speed / duration)*1000)*0.0078125) { pk = (long)(((speed / duration)*1000)*0.0078125); } //peak.setText(pk + " kbps"); } } });*/ //in.close(); if (result) { updateUI(status, "Uploaded"); // toast("Uploading succeeded"); // toast("Uploaded at /test.txt"); //duration = ((System.currentTimeMillis() - started)-sleepingTime) / 1000; System.out.println("curreent time..... "+System.currentTimeMillis()); System.out.println("started time --"+started); System.out.println("sleep tome...."+sleepingTime); System.out.println("duration is....."+duration); runOnUiThread(new Runnable() { public void run() { bar.setProgress(progress); // trans.setText("" + progress); //duration = ((System.currentTimeMillis() - started)-sleepingTime) / 1000; real_time.setText(duration + " secs"); if (duration != 0) { test_avg.setText((speed / duration) / 1024 + " kbps"); if (pk <= (speed / duration) / 1024) { pk = (speed / duration) / 1024; } peak.setText(pk + " kbps"); } } }); } /*while(!result){Thread.sleep(1000);}*/ } in.close();

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• bandwidth throttling C linux

  - by bob moch

  hi im currently creating a function to create a sleep time i can pause between packets for my port scanner im creating for personal/educational use for my home network. what im currently doing is opening /proc/net/dev and reading the 9th set of digits for the eth0 interface to find out the current packets being set and then reading it again and doing some math to figure out a delay to sleep between sending a packet to a port to identify it and fingerprint it. my problem is that no matter what throttle % i use it always seems to send the same rate of packets. i think its mainly my way of mathematically creating my sleep delay. edit:: dont mind the function declaration and the struct stuff all im doing is spawning this function in a thread and passing a pointer to a struct to the function, recreating the struct locally and then freeing the passed structs memory. void *bandwidthmonitor_cmd(void *param) { char cmdline[1024], *bytedata[19]; int i = 0, ii = 0; long long prevbytes = 0, currentbytes = 0, elapsedbytes = 0, byteusage = 0, maxthrottle = 0; command_struct bandwidth = *((command_struct *)param); free(param); //printf("speed: %d\n throttle: %d\n\n", UPLOAD_SPEED, bandwidth.throttle); maxthrottle = UPLOAD_SPEED * bandwidth.throttle / 100; //printf("max throttle:%lld\n", maxthrottle); FILE *f = fopen("/proc/net/dev", "r"); if(f != NULL) { while(1) { while(fgets(cmdline, sizeof(cmdline), f) != NULL) { cmdline[strlen(cmdline)] = '\0'; if(strncmp(cmdline, " eth0", 6) == 0) { bytedata[0] = strtok(cmdline, " "); while(bytedata[i] != NULL) { i++; bytedata[i] = strtok(NULL, " "); } bytedata[i + 1] = '\0'; currentbytes = atoi(bytedata[9]); } } i = 0; rewind(f); elapsedbytes = currentbytes - prevbytes; prevbytes = currentbytes; byteusage = 8 * (elapsedbytes / 1024); //printf("usage:%lld\n",byteusage); if(ii & 0x40) { SLEEP += (maxthrottle - byteusage) * -1.1;//-2.5; if(SLEEP < 0){ SLEEP = 0; } //printf("sleep:%d\n", SLEEP); } usleep(25000); ii++; } } return NULL; } SLEEP and UPLOAD_SPEED are global variables and UPLOAD_SPEED is in kb/s and generated via a speedtest function that gets the upload speed of my computer. this function is running inside a POSIX thread updating SLEEP which my threads doing the socket work grab to sleep by after every packet. as testing instead of only doing the ports i want to check i make it do all the ports over and over again so i can run dstat on a machine to check bandwidth and no matter what bandwidth.throttle is set to it always seems to generate the same amount of bandwidth to the dstat machine. the way i calculate how much i "should" throttle by is by finding the maximum throttle speed which is defined as maxthrottle = upload_speed * throttle / 100; for example if my upload speed was 1000kb/s and my throttle was 90 (90%) my max throttle would be 900kb/s from there it would find the current bytes sent from /proc/net/dev and then find my sleep time via incrementing or decrementing it via sleep += (maxthrottle - bytesysed) * -1.1; this should in theory increase or decrease the sleep time based on how many bytes used there are. the if(ii & 0x40) statement is just for some moderation control. it makes it so it only sets sleep to a new time every 30-40 iterations. final notes: the main problem is that the sleep timer does not seem to modify the speed of packets being set. or maybe its just my implementation because on a freshly restarted machine where /proc/net/dev has low numbers of bytes sent it seems to raise the sleep timer accordingly on my 60kb/s upload machine (ex if i set the throttle to 2 it will incline the sleep timer until network bandwidth out reaches the max bandwidth threshold, but when i try running it on a server which as been online forever it doesnt seem to work as nicely if at all. if anyone can suggest a new method of monitoring the network to adjust a sleep delay then let me know or if anyone sees a flaw in my code. thank you.

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• C#.NET Problem with locking of page after writing stream to window.

  - by godlikeskills

  The code below works fine, the problem is the 1st two lines are appearing on screen. It basically loads the PDF but I can't see the btnAcceptProposal change name or become enabled. Tried a Thread for the load but it broke. Anyone got any ideas - it's a web application protected void btnPDFProposal_Click(object sender, EventArgs e) { btnAcceptProposal.Enabled = true; btnAcceptProposal.Text = "sss"; byte[] p = Order.Proposal; Response.AppendHeader("content-disposition", "attachment; filename=Proposal.pdf"); Response.ContentType = "Application/pdf"; Response.Clear(); Response.BinaryWrite(p); Response.End(); }

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• Delays in ActionScript (Flash)? Alternatives to setInterval

  - by yar

  While setInterval is handy, it's kind of limiting. Every time I want to add a Tween I have to add a new method. I do not want to alter the structure of my code just to add in some delays. Isn't there any way to say this without making methods for A and B? // do A // wait N seconds // do B I don't want to use a while loop with Dates because I think it will be blocking. Isn't there anything like Thread.sleep in ActionScript?

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• Android SurfaceView/Canvas flickering after trying to clear it

  - by Mark D

  So I am trying to clear the Canvas using canvas.drawColor(Color.BLACK) but if I just call this once, the display flickers and displays the old drawing which should have been covered up by the drawColor. Here is the important bits of my code - public void update() { //This method is called by a Thread Canvas canvas = holder.lockCanvas(null); if (canvas != null) { onDraw(canvas); } holder.unlockCanvasAndPost(canvas); } @Override protected void onDraw(Canvas canvas) { if (toClear) { canvas.drawColor(Color.BLACK); //if this is not set to change back to false, it does not flicker toClear = false; } //Draw some objects that are moving around } public void clearScreen() { //This method is called when the user pressed a button toClear = true; } After Googling around a litte, I heard about double buffering but came to the understanding that lockCanvas() and unlockCanvasAndPost() should handle this for me. What is going wrong here?

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• Handling orientation changes yourself

  - by synic

  From the documentation regarding the android:configChanges='orientation' attribute of the activity tag in the manifest: Note: Using this attribute should be avoided and used only as a last-resort. Please read Handling Runtime Changes for more information about how to properly handle a restart due to a configuration change. Why does it say this? In the case of threads and networking requests via a service API library, a request could be made with a reference to the original Activity, and then an orientation change could occur, leaving the thread pointing to the old Activity. While this can be fixed, it's tedious and ugly compared to just handling the configuration changes yourself. Why should it be avoided?

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• How can I (reasonably) precisely perform an action every N milliseconds?

  - by Jon Cage

  I have a machine which uses an NTP client to sync up to internet time so it's system clock should be fairly accurate. I've got an application which I'm developing which logs data in real time, processes it and then passes it on. What I'd like to do now is output that data every N milliseconds aligned with the system clock. So for example if I wanted to do 20ms intervals, my oututs ought to be something like this: 13:15:05:0000 13:15:05:0020 13:15:05:0040 13:15:05:0060 I've seen suggestions for using the stopwatch class, but that only measures time spans as opposed to looking for specific time stamps. The code to do this is running in it's own thread, so should be a problem if I need to do some relatively blocking calls. Any suggestions on how to achieve this to a reasonable (close to or better than 1ms precision would be nice) would be very gratefully received.

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• How to get left-top and right-buttom latitude and longitude of map in MapKit For iPad ?

  - by damniatx

  Hi, i'm looking for answer about getting latitude and longitude from uimapkit. there is same problem that has been answered, but it didn't give right coordinate. http://yit.me/3ddp73 it's code from thread i'm linking above. CLLocationCoordinate2D topLeft, bottomRight; topLeft = [mapView convertPoint:CGPointMake(0,0) toCoordinateFromView:mapView]; CGPoint pointBottomRight = CGPointMake(mapView.frame.size.width, mapView.frame.size.height); bottomRight = [mapView convertPoint:pointBottomRight toCoordinateFromView:mapView]; NSLog(@"topleft = %f", topLeft); NSLog(@"bottom right = %f", bottomRight); any idea to fix this issue ? thanks

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• Is there a way to embed an mp3 player in a website that isn't flash based (so that the website is iP

  - by hartleybrody

  I did a lot of searching for what I thought would be a pretty common question, but I came up with nothing. If there is another thread with a similar topic, please let me know. Basically, I'm looking for a way to have an .mp3 file play in a website without relying on a flash-based player. I've searched w3 schools and every forum I can think of, but every media player I've found so far has been some sort of proprietary flash player. Doesn't HTML support some sort of native player? I've found some that rely on Windows Media Player which is close, but I want the player to work on an iPhone and something tells me WMP won't get that done... PS, as I'm thinking more about this this idea just popped into my head: a javascipt player and inside the <noscript> tag, put a flash player? I'm running a music blog (@ http://www.freshoncampus.com) so the less code per post, the better...

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• AtomicInteger for limited sequnce generation

  - by satish

  How can we use AtomicInteger for limited sequence generation say the sequence number has to be between 1 to 60. Once the sequece reaches 60 it has to start again from 1. I wrote this code though not quite sure wether this is thread safe or not? public int getNextValue() { int v; do { v = val.get(); if ( v == 60) { val.set(1); } } while (!val.compareAndSet(v , v + 1)); return v + 1; }

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• ArrayIndexOutOfBound exception even though I check for array length!

  - by xtracto

  I have the following code in some app: int lowRange=50; int[] ageRangeIndividual = {6, 10, 18, 25, 45, 65, 90}; int index=0; for (; index<ageRangeIndividual.length-1 && ageRangeIndividual[index]<=lowRange;index++); I am getting an "Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 7" in the for line! even though I explicitly specify to break the cycle if index < last indexable item in the array! This does not happen always, but after some time of running said program (lowRange varies each time the function is called) What am I not seeing?

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• Getting Reference to Calling Activity from AsyncTask (NOT as an inner class)

  - by stormin986

  Is it at all possible, from within an AsyncTask that is NOT an inner class of the calling Activity class, to get a reference to the instance of Activity that initiated execution of the AsyncTask? I am aware of this thread, however it doesn't exactly address how to reference the calling Activity. Some suggest passing a reference to the Activity as a parameter to the AsyncTask constructor, however, it's reported that doing so will always result in a NullPointerException. So, I'm at a loss. My AsyncTask provides robust functionality, and I don't want to have to duplicate it as an inner class in every Activity that wants to use it. There must be an elegant solution.

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• Mysql with innodb and serializable transaction does not (always) lock rows

  - by Tobias G.

  Hello, I have a transaction with a SELECT and possible INSERT. For concurrency reasons, I added FOR UPDATE to the SELECT. To prevent phantom rows, I'm using the SERIALIZABLE transaction isolation level. This all works fine when there are any rows in the table, but not if the table is empty. When the table is empty, the SELECT FOR UPDATE does not do any (exclusive) locking and a concurrent thread/process can issue the same SELECT FOR UPDATE without being locked. CREATE TABLE t ( id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, display_order INT ) ENGINE = InnoDB; SET TRANSACTION ISOLATION LEVEL SERIALIZABLE; START TRANSACTION; SELECT COALESCE(MAX(display_order), 0) + 1 from t FOR UPDATE; .. This concept works as expected with SQL Server, but not with MySQL. Any ideas on what I'm doing wrong? EDIT Adding an index on display_order does not change the behavior.

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• Jquery, div with two classes hide one show the other - conflict?????

  - by user349223

  Sorry if this was answered in a previous thread, i couldn't find one. I have 4 sections: Section1, Section2, Section3, Section4 There are classes for each section, so I am hiding and showing based on the section. The problem is some classes need to be showin in Section1 and Section2. <div class="section1 section2"> blah blah </div> $('a.homeLink').click(function(){ $('.section1').show(); $('.section2, .section3, .section4').hide(); return false; }); As you see in this case I have a div in two sections, but as i thought would happen it remains hidden due to hiding class section2 work arounds or solutions?? thanks

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