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  • Elegant way to add functionallity to previously defined functions

    - by Bastiaan
    How to combine two functions together I have a class controlling some hardware: class Heater() def set_power(self,dutycycle, period) ... def turn_on(self) ... def turn_off(self) And a class that connects to a database and handles all data logging fuctionallity for an experiment: class DataLogger() def __init__(self) # Record measurements and controls in a database def start(self,t) # Starts a new thread to aqcuire and reccord measuements every t secconds Now, in my program recipe.py I want to do something like: log = DataLogger() @DataLogger_decorator H1 = Heater() log.start(60) H1.set_power(10,100) H1.turn_on() sleep(10) H1.turn_off() etc Where all actions on H1 are recorded by the datalogger. I can change any of the classes involved, just looking for an elegant way to do this. Ideally the hardware functions remain separated from the database and DataLogger functions. And ideally the DataLogger is reusable for other controls and measurements.

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  • Take advantage of multiple cores executing SQL statements

    - by willvv
    I have a small application that reads XML files and inserts the information on a SQL DB. There are ~ 300 000 files to import, each one with ~ 1000 records. I started the application on 20% of the files and it has been running for 18 hours now, I hope I can improve this time for the rest of the files. I'm not using a multi-thread approach, but since the computer I'm running the process on has 4 cores I was thinking on doing it to get some improvement on the performance (although I guess the main problem is the I/O and not only the processing). I was thinking on using the BeginExecutingNonQuery() method on the SqlCommand object I create for each insertion, but I don't know if I should limit the max amount of simultaneous threads (nor I know how to do it). What's your advice to get the best CPU utilization? Thanks

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  • Jmeter Query new user

    - by Sri
    First of all apologies for the below question. Am from a Testing background for the past 8 years and very novice to Jmeter. I went through the Jmeter site, and ran a sample recording using the jmeter.apache.org site and it went fine. I want to test my knowledge and understanding. So, I did the following way. Created a thread group. Added a config element HTTP Default Requests with server name as mail.google.com. Added a Sampler as HTTP request, set the METHOD to POST and gave the username and password, and i ran the test. When i see the Results Viewer, i could see the login page of gmail, I need to know how to pass my username and password and simulate the clicking of Submit button and getting the next page. Please help, am very new and will really appreciate if it's explained as simple as possible.

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  • Commands implicitly threaded in Makefiles ?

    - by apple92
    Hi, I have a "super" makefile which launches two "sub" make file: libwebcam: @echo -e "\nInvoking libwebcam make." $(MAKE) -C $(TOPDIR)/libwebcam uvcdynctrl: @echo -e "\nInvoking uvcdynctrl make." $(MAKE) -C $(TOPDIR)/uvcdynctrl uvcdynctrl uses libwebcam... I noticed that those two builds are launched as separate threads by make ! Thus sometimes the lib is not available when uvcdynctrl starts being built, and I get errors. By default, make should not launch commands as threads since this is available only through -j (number of jobs) and, according to the make manual, there is no thread by default. I run this on an Ubuntu. Did someone face the same issue ? Apple92

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  • What is the absolute fastest way to implement a concurrent queue with ONLY one consumer and one producer?

    - by JohnPristine
    java.util.concurrent.ConcurrentLinkedQueue comes to mind, but is it really optimum for this two-thread scenario? I am looking for the minimum latency possible on both sides (producer and consumer). If the queue is empty you can immediately return null AND if the queue is full you can immediately discard the entry you are offering. Does ConcurrentLinkedQueue use super fast and light locks (AtomicBoolean) ? Has anyone benchmarked ConcurrentLinkedQueue or knows about the ultimate fastest way of doing that? Additional Details: I imagine the queue should be a fair one, meaning the consumer should not make the consumer wait any longer than it needs (by front-running it) and vice-versa.

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  • Queued WCF Service which processes every X seconds

    - by Jeff Windsor
    I need to create a service which can process queued requests on a configured time interval. For example go to the web and get financial data from a site the requires we limit requests to once per second. I am new to WCF and I am not sure if (1) WCF with MSMQ a proper choice for implementing this? and (2) if so what is the best mechanism for enforcing the interval? a thread wait? a timer (not sure how that would work).

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  • UITableViewController executes delate functions before network request finishes

    - by user1543132
    I'm having trouble trying to populate a UITableView with the results of a network request. It seems that my code is alright as it works perfectly when my network is speedy, however, when it's not, the function - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath- still executes, which results in a bad access error. I presume that this is because the array that the aforesaid function attempts to utilize has not been populated. This brings me to my question: Is there anyway that I can have the UITableView delegate methods delayed to avoid this? - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *CellIdentifier = @"AlbumsCell"; //UITableViewCell *basicCell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath]; AlbumsCell *cell = (AlbumsCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier]; if (!cell) { **// Here is where the Thread 1: EXC_BAD_ACCESS (code=2 address=0x8)** cell = [[[AlbumsCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; } Album *album = [_albums objectAtIndex:[indexPath row]]; [cell setAlbum:album]; return cell; }

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  • Creating a System.Windows.Controls.Image throws an exception - how do I use the dispatcher to instan

    - by Scott Whitlock
    I'm running my unit tests on a piece of code that does the following in the test: Assert.IsNotNull(target.Icon); Inside the getter for the Icon property, I'm doing this: System.Windows.Controls.Image img = new System.Windows.Controls.Image(); That's throwing this exception: System.InvalidOperationException : The calling thread must be STA, because many UI components require this. I understand what that means, and I understand that I need to use the Dispatcher, but I'm a bit confused about how or why... this is a property of my ViewModel and I don't get any of these exceptions when running the application. Other info: this only started failing when I upgraded to .NET 4.

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  • How do I guarantee row uniqueness in MySQL without the use of a UNIQUE constraint?

    - by MalcomTucker
    Hi I have some fairly simple requirements but I'm not sure how I implement them: I have multiple concurrent threads running the same query The query supplies a 'string' value - if it exists in the table, the query should return the id of the matching row, if not the query should insert the 'string' value and return the last inserted id The 'string' column is (and must be) a text column (it's bigger than varchar 255) so I cannot set it as unique - uniqueness must be enforced through the access mechanism The query needs to be in stored procedure format (which doesnt support table locks in MySQL) How can I guarantee that 'string' is unique? How can I prevent other threads writing to the table after another thread has read it and found no matching 'string' item? Thanks for any advice..

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  • Lua operations, that works in mutitheaded environment

    - by SBKarr
    My application uses Lua in multithreaded environment with global mutex. It implemented like this: Thread locks mutex, Call lua_newthread Perform some initialization on coroutine Run lua_resume on coroutine Unlocks mutex lua_lock/unlock is not implemented, GC is stopped, when lua works with coroutine. My question is, can I perform steps 2 and 3 without locking, if initialisation process does not requires any global Lua structs? Can i perform all this process without locking at all, if coroutine does not requires globals too? In what case I generally can use Lua functions without locking?

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  • embedded dev. question - how to break free from a faulty serial port opening?

    - by user347266
    Under WindowsCE, C++ project, I'm trying to work with devices connected via both "real" serial ports and/or serial-to-usb wrappers ("virtual" serial ports); my problem is - when I try to open the port, if something goes wrong, the function never returns and the system goes into some non-responsive state and has to be eventually rebooted. I need to open the ports from the main thread. The question is - how can I make it happen in a controlled way?? this is the opening code snippet: std::ostringstream device_name; device_name << "\\.\COM" << port; m_port = ::CreateFile(device_name.str().c_str(), GENERIC_READ | GENERIC_WRITE, 0, // exclusive access NULL, // no security OPEN_EXISTING, FILE_FLAG_OVERLAPPED, // overlapped I/O NULL); // null template any suggestions would be greatly appreciated thanks!

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  • Project works in eclipse but not when exported

    - by Mike
    I wrote an application that uses GraphViz to generate some graphs as .gif's according to the DOT syntax. When I run from Eclipse the images are generated fine but when I export it as a jar the images are created but there is no data in them. When I view them in Microsoft Picture Viewer its just the red X. It was working as an exported jar until I put the picture generation in its own thread. I can't seem to figure out whats going on here. Are there any problems exporting multi-threaded projects? Any one have any ideas? Thanks

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  • How does lock(syncRoot) make sense on a static method?

    - by Rising Star
    The following code is excerpted from the (Windows Identity Foundation SDK) template that MS uses to create a new Security Token Service Web Site. public static CustomSecurityTokenServiceConfiguration Current { get { HttpApplicationState httpAppState = HttpContext.Current.Application; CustomSecurityTokenServiceConfiguration customConfiguration = httpAppState.Get( CustomSecurityTokenServiceConfigurationKey ) as CustomSecurityTokenServiceConfiguration; if ( customConfiguration == null ) { lock ( syncRoot ) { customConfiguration = httpAppState.Get( CustomSecurityTokenServiceConfigurationKey ) as CustomSecurityTokenServiceConfiguration; if ( customConfiguration == null ) { customConfiguration = new CustomSecurityTokenServiceConfiguration(); httpAppState.Add( CustomSecurityTokenServiceConfigurationKey, customConfiguration ); } } } return customConfiguration; } } I'm relatively new to multi-threaded programming. I assume that the reason for the lock statement is to make this code thread-safe in the event that two web requests arrive at the web site at the same time. However, I would have thought that using lock (syncRoot) would not make sense because syncRoot refers to the current instance that this method is operating on... but this is a static method? How does this make sense?

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  • SQL Server concurrency and generated sequence

    - by Goyuix
    I need a sequence of numbers for an application, and I am hoping to leverage the abilities of SQL Server to do it. I have created the following table and procedure (in SQL Server 2005): CREATE TABLE sequences ( seq_name varchar(50) NOT NULL, seq_value int NOT NULL ) CREATE PROCEDURE nextval @seq_name varchar(50) AS BEGIN DECLARE @seq_value INT SET @seq_value = -1 UPDATE sequences SET @seq_value = seq_value = seq_value + 1 WHERE seq_name = @seq_name RETURN @seq_value END I am a little concerned that without locking the table/row another request could happen concurrently and end up returning the same number to another thread or client. This would be very bad obviously. Is this design safe in this regard? Is there something I can add that would add the necessary locking to make it safe? Note: I am aware of IDENTITY inserts in SQL Server - and that is not what I am looking for this in particular case. Specifically, I don't want to be inserting/deleting rows. This is basically to have a central table that manages the sequential number generator for a bunch of sequences.

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  • [grails + xfire] How to handle errors in SOAP services?

    - by Mulone
    Hi all, I'm implementing a web service on the xfire plugin. I was wondering how I'm supposed to handle the errors. I tried with this setup but the error is not returned to the SOAP client: GaSession[] myMethod( String userId ) throws MyException{ GaUser user = GaUser.findByUserId( userId ) if (!user) throw new MyException("user ${userId} does not exist") // do stuff and return valid results } Is there a standard way to handle errors and return them to the client in a clear way? My log is full of messages like: 2010-06-13 18:20:40,926 [Thread-289] DEBUG aegis.XMLClassMetaInfoManager - Mapping file : /com/mycompany/MyClass.aegis.xml not found. Is there a way to fix this? Cheers!

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  • Running a packaged exe in the same folder as the installed firefox extension

    - by mustafabar
    I have read this thread, and some other How to run a local exe in my firefox extension The problem is, at deployment and using firefox 4.0.1, if I install the .xpi extension, the xpi is put inside the \Profiles...\extensions as **.xpi, which is a compressed format All the solutions assume that the the extension is put in a folder, thus they are accessing the folder as is, which I cannot do for example this guy says //**** get profile folder path **** var dsprops = Components.classes['@mozilla.org/file/directory_service;1'] .getService(Components.interfaces.nsIProperties); var ProfilePath = dsprops.get("ProfD", Components.interfaces.nsIFile).path; //**** initialize file **** var file = Components.classes["@mozilla.org/file/local;1"] .createInstance(Components.interfaces.nsILocalFile); file.initWithPath(ProfilePath); //**** append each step in the path **** file.append("extensions"); file.append("guid"); file.append("sample.exe"); guid in my case is installed as {f13b157f-b174-47e7-a34d-4815ddfdfeb8}.xpi which cannot be accessible this way

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  • java version 1.6 applet requistes

    - by gautam
    Hi, I upgraded my java version 1.5 to 1.6. My applet is not working what are prequesties ? i have changed classid and MIME type to 1.6. Its giving exception: load: class com.timer.AppletGenerator.class not found. java.lang.ClassNotFoundException: com.timer.AppletGenerator.class at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source) at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source) at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source) at java.lang.Thread.run(Unknown Source) Caused by: java.io.IOException: open HTTP connection failed:http://localhost:8080/Perfmonitoringgui-000.004.000/com/timer/AppletGenerator/class.class at sun.plugin2.applet.Applet2ClassLoader.getBytes(Unknown Source) at sun.plugin2.applet.Applet2ClassLoader.access$000(Unknown Source) at sun.plugin2.applet.Applet2ClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) ... 7 more Exception: java.lang.ClassNotFoundException: com.timer.AppletGenerator.class Thanks

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  • Wait for animation, render to complete - XAML and C#

    - by Adam S
    Hi all. I have a situation where I am animating part of my XAML application, and I need to wait for the animation AND rendering to complete before I can move on in my code. So far the tail end of my function looks like: ProcExpandCollapse.Begin(); while (ProcExpandCollapse.GetCurrentState() != ClockState.Stopped) { } } Which, in theory, will wait until the animation is finished. But it will not wait until the rendering is finished - the thread drawing the application might still not have re-drawn the animation. The animation is expanding a UIElement, and then the next part of my code uses it's rendered size to do some things. My question then is, how do I wait until my UI Element is re-rendered before moving on?

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  • CSS or JS max. character <h2> and replace end with "..."

    - by cr0z3r
    Hey I assume my title basically summed it all up. I have a <h2> title, and I want it to have a max character property, be it CSS or javascript, so that whenever this maximum limit is passed, the title's end is replaced by ... (three dots). Thank you very much in advance. An example can be viewed here: http://themeforest.net/forums/thread/now-accepting-bargain-submissions/23205 (see the title) P.S. Any idea why I had to create a new user? the login-feature through google doesn't recognize my previous user :(

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  • Can I overwrite an Object that has been Locked() in C#?

    - by makerofthings7
    I have a few objects that I'd like to send to the server, but I want to make sure that this is the only thread that moving the data from Stage to Upload. Is the following code valid in a multithreaded environment? List<CounterInternal> UploadToServer = new List<CounterInternal>(); List<CounterInternal> StagingQueue = new List<CounterInternal>(); lock (this.UploadToServer) lock (this.StagingQueue) { if (UploadToServer.Count == 0) { UploadToServer = StagingQueue.DoDeepCopyExtensionMethod(); // is the following line valid given that I have a Lock() on it? StagingQueue = new List<CounterInternal>(); } } }

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  • asp.net impersonation identity: Where does it come from?

    - by Rising Star
    Here's a simple question I've been stuck on for a while. When I set < identity impersonate=true > in my web.config so that asp.net impersonates the logged on user automatically (or the anonymous account if not using Windows Authentication), where does the identity that asp.net impersonates come from? This document: http://msdn.microsoft.com/en-us/library/ff649264.aspx shows three places you can retrieve information about the logged on user: Httpcontext.Current.user System.Threading.Thread.Current System.Security.Principal.WindowsIdentity.GetCurrent It seems that none of these locations consistently match the identity that gets impersonated when I set < identity impersonate=true > in web.config. I would like to know where the impersonated identity comes from.

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  • Word VBA: How to know if the actual save operation is completed?

    - by Edwin
    Hi, I am having a problem with the Document.SaveAs method in Word VBA with large Word documents, it seems that the save operation is asynchronous, ie. after calling SaveAs it returns immediately, but with large Word documents the actual save operation may not has been completed and it's in progress in another thread. So what I want to ask is that if there is a way to detect if the actual save operation is in progress or finished? PS. I use Delphi to call the automation interface of Word, if it means something in discussing this problem, but I don't' think so? Thank you in advance.

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  • passing parameter to dowork?

    - by safi
    How can i Pass parameter to background_DoWork? public void bgw1_DoWork(Object sender, DoWorkEventArgs e) { make_zip_file argumentest = e.Argument as make_zip_file; Thread.Sleep(100); argumentest.return_path = argumentest.Makezipfile(files, IsOriginal); e.Result = argumentest; } i need to pass files,isOrginal parameter...? i am calling this method: public string run_async() { bgw1.DoWork += bgw1_DoWork; bgw1.RunWorkerCompleted += bgw1_RunWorkerCompleted; make_zip_file mzf2 = new make_zip_file(); bgw1.RunWorkerAsync(); return return_path; }

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  • Re-ordering C++ template functions

    - by DeadMG
    In C++, I have a certain template function that, on a given condition, calls a template function in another class. The trouble is that the other class requires the full definition of the first class to be implemented, as it creates the second class and stores them and manages them in similar fashions. The trouble is that naturally, they fall as one class, and thus have some tight interop, except that I need them to be two classes for threading reasons. A sort of, master for all threads, one child per thread, system. Any advice on how this can be implemented?

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  • Does Anyone Still Prefer N-Tier Architecture After Having *Shipped* an MVC Application?

    - by Jim G.
    Other SO threads have asked people if they prefer N-Tier or MVC architecture. I'm not looking to continue that debate on this thread. I'm looking for something more specific. My Question: Does Anyone Still Prefer N-Tier Architecture After Having Shipped an MVC Application? Reason for My Question: Before I shipped an MVC web application, I wasn't convinced that it was superior to N-Tier Architecture. Specifically, if better unit testing was the only obvious benefit of MVC, then I saw no reason to switch gears and adopt a new architecture. But after having shipped an MVC application, I can see many benefits (which have been enumerated on other threads).

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