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  • C# - periodic data reading and Thread.Sleep()

    - by CaldonCZE
    Hello, my C# application reads data from special USB device. The data are read as so-called "messages", each of them having 24 bytes. The amount of messages that must be read per second may differ (maximal frequency is quite high, about 700 messages per second), but the application must read them all. The only way to read the messages is by calling function "ReadMessage", that returns one message read from the device. The function is from external DLL and I cannot modify it. My solution: I've got a seperate thread, that is running all the time during the program run and it's only job is to read the messages in cycle. The received messages are then processed in main application thread. The function executed in the "reading thread" is the following: private void ReadingThreadFunction() { int cycleCount; try { while (this.keepReceivingMessages) { cycleCount++; TRxMsg receivedMessage; ReadMessage(devHandle, out receivedMessage); //...do something with the message... } } catch { //... catch exception if reading failed... } } This solution works fine and all messages are correctly received. However, the application consumes too much resources, the CPU of my computer runs at more than 80%. Therefore I'd like to reduce it. Thanks to the "cycleCount" variable I know that the "cycling speed" of the thread is about 40 000 cycles per second. This is unnecessarily too much, since I need to receive maximum 700 messagges/sec. (and the device has buffer for about 100 messages, so the cycle speed can be even a little lower) I tried to reduce the cycle speed by suspending the thread for 1 ms by Thread.Sleep(1); command. Of course, this didn't work and the cycle speed became about 70 cycles/second which was not enough to read all messages. I know that this attempt was silly, that putting the thread to sleep and then waking him up takes much longer than 1 ms. However, I don't know what else to do: Is there some other way how to slow the thread execution down (to reduce CPU consumption) other than Thread.Sleep? Or am I completely wrong and should I use something different for this task instead of Thread, maybe Threading.Timer or ThreadPool? Thanks a lot in advance for all suggestions. This is my first question here and I'm a beginner at using threads, so please excuse me if it's not clear enough.

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  • How to build a database from an XSD schema and import XML data

    - by FreshCode
    I have a complex XSD schema and hundreds of XML files conforming to the schema. How do I automate the creation of related SQL Server tables to store the XML data? I've considered creating C# classes from the XSD schema using the xsd.exe tool and letting something like Subsonic figure out how to make a shiny database out of it, but not sure if it's the best way to approach it. Has anyone managed to elegantly import XSD files into SQL Server?

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  • Retrieving Data in A NSTableView

    - by Heisennberg
    I have a three column Table View populated by two NSMutableDictionaries which share the same keys (ie key | value1 | value2 ) with dict1(key,value1) and dict2(key,value2). I want to manually enter data in the third column and create the key/value objects in dict2. But when I do that, my code picks the wrong key :S Here's the code for the delegate : - (void)tableView:(NSTableView *)aTableView setObjectValue:(id)anObject forTableColumn:(NSTableColumn *)aTableColumn row:(NSInteger)rowIndex { if ([[aTableColumn identifier] isEqualToString:@"value2"]) { [dict2 setValue:anObject forKey:[[[aTableView tableColumnWithIdentifier:@"key"] dataCellForRow:rowIndex] stringValue ]]; } } Any idea ?

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  • converting tag number to int

    - by Ehtesham Sajed
    i m using Visual C++2008. i've assigned tag value=2 of all buttons from button property(using drag n drop). now i want to make some math calculation with tag value. need to change it in int. what is the default data type tag? i used this code, //code sample if(((int)this-button1-Tag)((int)this-button2-Tag)((int)this-button3-Tag)==50) { ........ //i.e, if tag value of button1*tag value of button2*tag value of button 3==50 then... ........ } generated following run time error on a messegebox An unhandled exception of type 'System.InvalidCastException' occurred in learncpp1.exe Additional information: Specified cast is not valid.

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  • Calculating average (AVG) and grouping by week on large data set takes too long

    - by caioiglesias
    I'm getting average prices by week on 7 million rows, it's taking around 30 seconds to get the job done. This is the simple query: SELECT AVG(price) as price, yearWEEK(FROM_UNIXTIME(timelog)) as week from pricehistory where timelog > $range and product_id = $id GROUP BY week The only week that actually gets data changed and is worth averaging every time is always the last one, so this calculation for the whole period is a waste of resources. I just wanted to know if mysql has a tool to help out on this.

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  • Tool to maintain a Data Mapping between two systems

    - by ktaylorjohn
    We have XML interfaces between multiple systems. An Enterprise Domain Model is missing in the overall architecture, hence the terms Product/Customer/User means different things to different systems. We currently use excel sheets to map the elements in incoming XML to what the actual Field means within our system. Additionally, it contains the values of Mandatory/Optional and length of each field. We call this the Data Dictionary. Any changes to the XML go through rounds of deliberation and updates to Word and Excel documents. Is there a better way to do this? Any tool/GUI based approach which all systems and owners can view?

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  • FormsAuthentication AuthCookie data type

    - by FreshCode
    Does the original data type of the username string in a call to FormsAuthentication.SetAuthCookie(...) make any difference with regards to security or code maintainability? As I understand it, the cookie is encrypted and used to identify a user on each request. I'm curious whether it should affect the design of the primary key on my Users table in my database, eg. Guid vs int or a unique username string.

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  • What data actually gets cached in InnoDB/MySQL?

    - by ming yeow
    Hi folks, i am trying to optimize performance for my database. My question is - what get cached in the db memory? For example: (table with 2 columns: key (indexed), data (not indexed) updated (not indexed) Select * where updated=20100202 (the db will do a scan - will the scanned rows be kept in memory?) Select * where key = 20 (the db will refer to the index - will the identified rows be kept in memory?)

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  • How to prevent illegal file and folder name creation in Windows Server 2003 or Windows Server 2008

    - by Joel Thibeault
    Preventing illegal file and Folder name creation on a Windows 2003/2008 file server is the goal. We know from articles like http://stackoverflow.com/questions/62771/how-check-if-given-string-is-legal-allowed-file-name-under-windows that for some reason the file system allows creation of illegal file/folder chacters and paths that exceed the limitations of Windows. I need the following question answered: How to remove cabability to create file or folder creation in NTFS that contains invalid characters? Can you remove the POSIX subsystem from Windows to fix this issue? How does disabling 8.3 dos name creation factor into this issue? Will any of these fixes prevent linux clients from creating windows compliant files?

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  • SQL OUTER JOIN with NEWID to generate random data for each row

    - by CL4NCY
    Hi, I want to generate some test data so for each row in a table I want to insert 10 random rows in another, see below: INSERT INTO CarFeatures (carID, featureID) SELECT C.ID, F.ID FROM dbo.Cars AS C OUTER APPLY ( SELECT TOP 10 ID FROM dbo.Features ORDER BY NEWID() ) AS F Only trouble is this returns the same values for each row. How do I order them randomly?

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  • MySQL select date, join statistic data - how?

    - by Webnet
    I have some statistics I need to report on a monthly basis. I need my query to return 0's for statistics which aren't there. The only way I know to do this is to use SQL to generate a list of days within the specified time period and LEFT JOIN the statistic data that I need to report on. Problem is.... I've never not selected from a table like that... how do I do that?

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  • Mysql query to fetch data

    - by hnihar
    i have a table "request" with 4 columns namely: 1.recId :long primary key 2.interactionId:long 3.requestedBy:boolean 4.requestedType:boolean and data is as follows: VALUES (185,455699,0,5), (186,455746,0,1), (187,455746,1,1), (188,455752,0,1), (189,455753,0,1), (190,455753,1,1), (191,455754,1,1) i want a query to fetch all the rows where interactionId is same and having requestedBy both 1 and 0 values and requestType=1; regards, Nihar

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  • Writing an OS for Motorola 68K processor. Can I emulate it? And can I test-drive OS development?

    - by ulver
    Next term, I'll need to write a basic operating system for Motorola 68K processor as part of a course lab material. Is there a Linux emulator of a basic hardware setup with that processor? So my partners and I can debug quicker on our computers instead of physically restarting the board and stuff. Is it possible to apply test-driven development technique to OS development? Code will be mostly assembly and C. What will be the main difficulties with trying to test-drive this? Any advice on how to do it?

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  • Can anyone provide Java program for btree or b+tree???

    - by rohit
    Hi, I am doing a project in which i require btree or b+tree data structure. but its not an important part of project. it would take my time to write a code for it. I googled it but didn't get anything.... So, can anyone provide java code for btree or b+tree implementation (with insert, delete, search algorithms)?????? it should accept string as input and form btree or b+tree of these string.

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  • Allocate from buffer in C

    - by Grimless
    I am building a simple particle system and want to use a single array buffer of structs to manage my particles. That said, I can't find a C function that allows me to malloc() and free() from an arbitrary buffer. Here is some pseudocode to show my intent: Particle* particles = (Particle*) malloc( sizeof(Particle) * numParticles ); Particle* firstParticle = <buffer_alloc>( particles ); initialize_particle( firstParticle ); // ... Some more stuff if (firstParticle->life < 0) <buffer_free>( firstParticle ); // @ program's end free(particles); Where <buffer_alloc> and <buffer_free> are functions that allocate and free memory chunks from arbitrary pointers (possibly with additional metadata such as buffer length, etc.). Do such functions exist and/or is there a better way to do this? Thank you!

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  • Flex Data Binding problem

    - by dta
    <mx:Label text="{(item1 as INewsItem).displayName}"/> For the above code in Flex, I get this warning : : Data binding will not be able to detect assignments to item1. Why? How to Fix it?

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  • Logging data with scribe

    - by lukatmyshu
    None of the scribe examples I've seen actually mention the best way to take logs/logfiles and send them to scribe. I could configure a logrotate script that has a postrotate section that "cats" the rotated file to scribe (but then I get minutes latency at best). The other option is to keep a "tail -f= | my_scribe_sender" and hope that the process never gets killed. However then you really can't guarantee that you're not missing/duplicating data.

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  • Load data to GdkPixbufLoader from g_input_stream_read

    - by sterh
    Hello, I load some data from file: GInputStream* input_stream; GFile *file = g_file_new_for_path(file_path); input_stream = g_file_read(file,generator_cancellable ,NULL); g_input_stream_read(input_stream, buffer, sizeof (buffer),generator_cancellable,error); How can i load g_input_stream_read function result to the GdkPixbufLoader object? Thank you.

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