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• Long running transactions with Spring and Hibernate?

  - by jimbokun

  The underlying problem I want to solve is running a task that generates several temporary tables in MySQL, which need to stay around long enough to fetch results from Java after they are created. Because of the size of the data involved, the task must be completed in batches. Each batch is a call to a stored procedure called through JDBC. The entire process can take half an hour or more for a large data set. To ensure access to the temporary tables, I run the entire task, start to finish, in a single Spring transaction with a TransactionCallbackWithoutResult. Otherwise, I could get a different connection that does not have access to the temporary tables (this would happen occasionally before I wrapped everything in a transaction). This worked fine in my development environment. However, in production I got the following exception: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction This happened when a different task tried to access some of the same tables during the execution of my long running transaction. What confuses me is that the long running transaction only inserts or updates into temporary tables. All access to non-temporary tables are selects only. From what documentation I can find, the default Spring transaction isolation level should not cause MySQL to block in this case. So my first question, is this the right approach? Can I ensure that I repeatedly get the same connection through a Hibernate template without a long running transaction? If the long running transaction approach is the correct one, what should I check in terms of isolation levels? Is my understanding correct that the default isolation level in Spring/MySQL transactions should not lock tables that are only accessed through selects? What can I do to debug which tables are causing the conflict, and prevent those tables from being locked by the transaction?

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• A monkey could do this better - Access to and availability of private member functions in C++

  - by David

  I am wandering the desert of my brain. I'm trying to write something like the following: class MyClass { // Peripherally Related Stuff public: void TakeAnAction(int oneThing, int anotherThing) { switch(oneThing){ case THING_A: TakeThisActionWith(anotherThing); break; //cases THINGS_NOT_A: }; private: void TakeThisActionWith(int thing) { string outcome = new string; outcome = LookUpOutcome(thing); // Do some stuff based on outcome return; } string LookUpOutcome(int key) { string oc = new string; oc = MyPrivateMap[key]; return oc; } map<int, string> MyPrivateMap; Then in the .cc file where I am actually using these things, while compiling the TakeAnAction section, it [CC, the solaris compiler] throws an an error: 'The function LookUpOutcome must have a prototype' and bombs out. In my header file, I have declared 'string LookUpOutcome(int key);' in the private section of the class. I have tried all sorts of variations. I tried to use 'this' for a little while, and it gave me 'Can only use this in non-static member function.' Sadly, I haven't declared anything static and these are all, putatively, member functions. I tried it [on TakeAnAction and LookUp] when I got the error, but I got something like, 'Can't access MyPrivateMap from LookUp'. MyPrivateMap could be made public and I could refer to it directly, I guess, but my sensibility says that is not the right way to go about this [that means that namespace scoped helper functions are out, I think]. I also guess I could just inline the lookup and subsequent other stuff, but my line-o-meter goes on tilt. I'm trying desperately not to kludge it.

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• Replace low level web-service reference call transport with custom one

  - by hoodoos

  I'm not sure if title sounds right actually, so I will give more explanation here. I will begin from very beginning :) I'm using c# and .net for my development. I have an application that makes requests to some soap web-service and for each user request it produces 3 to 10 requests for web-service, they should all run async to finish in one time, so I use Async method of the web-service generated reference and then wait for result on callback. But it seems like it starts a thread (or takes it from pool) for every async call I make, so if I have 10 clients I got to spawn 30 to 100 threads and it sounds terrible even for my 16 cores server :) So i wanted to replace low level transport implementation with my own which uses non-blocking sockets and can handle at least 50 sockets run parallel in one thread with not much overhead. But I actually dunno where to put my override best. I analyzed System.Web.Services.Protocols.SoapHttpClientProtocol class and see that it has some GetWebRequest method which I actually could use. If only I could somehow interupt the object it creates and get a http request with all headers and body from there and then send it with my own sockets.. Any ideas what approach to use? Or maybe there's something built in the framework I can use?

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• ISO/IEC Website and Charging for C and C++ Standards

  - by Michael Aaron Safyan

  The ISO C Standard (ISO/IEC 9899) and the ISO C++ Standard (ISO/IEC 14882) are not published online; instead, one must purchase the PDF for each of those standards. I am wondering what the rationale is behind this... is it not detrimental to both the C and C++ programming languages that the authoritative specification for these languages is not made freely available and searchable online? Doesn't this encourage the use of possibly inaccurate, non-authoritative sources for information regarding these standards? While I understand that much time and effort has gone into developing the C and C++ standards, I am still somewhat puzzled by the choice to charge for the specification. The OpenGroup Base Specification, for example, is available for free online; they make money buy charging for certification. Does anyone know why the ISO standards committees don't make their revenue in certifying standards compliance, instead of charging for these documents? Also, does anyone know if the ISO standards committee's atrociously looking website is intentionally made to look that way? It's as if they don't want people visiting and buying the spec. One last thing... the C and C++ standards are generally described as "open standards"... while I realize that this means that anyone is permitted to implement the standard, should that definition of "open" be revised? Charging for the standard rather than making it openly available seems contrary to the spirit of openness. P.S. I do have a copy of the ISO/IEC 9899:1999 and ISO/IEC 14882:2003, so please no remarks about being cheap or anything... although if you are tempted to say such things, you might want to consider the high school, undergraduate, and graduate students who might not have all that much extra cash. Also, you might want to consider the fact that the ISO website is really sketchy and they don't even tell you the cost until you proceed to the checkout... doesn't really encourage one to go and get a copy, now does it?

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• Fastest way to convert a list of doubles to a unique list of integers?

  - by javanix

  I am dealing with a MySQL table here that is keyed in a somewhat unfortunate way. Instead of using an auto increment table as a key, it uses a column of decimals to preserve order (presumably so its not too difficult to insert new rows while preserving a primary key and order). Before I go through and redo this table to something more sane, I need to figure out how to rekey it without breaking everything. What I would like to do is something that takes a list of doubles (the current keys) and outputs a list of integers (which can be cast down to doubles for rekeying). For example, input {1.00, 2.00, 2.50, 2.60, 3.00} would give output {1, 2, 3, 4, 5). Since this is a database, I also need to be able to update the rows nicely: UPDATE table SET `key`='3.00' WHERE `key`='2.50'; Can anyone think of a speedy algorithm to do this? My current thought is to read all of the doubles into a vector, take the size of the vector, and output a new vector with values from 1 => doubleVector.size. This seems pretty slow, since you wouldn't want to read every value into the vector if, for instance, only the last n/100 elements needed to be modified. I think there is probably something I can do in place, since only values after the first non-integer double need to be modified, but I can't for the life of me figure anything out that would let me update in place as well. For instance, setting 2.60 to 3.00 the first time you see 2.50 in the original key list would result in an error, since the key value 3.00 is already used for the table.

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• Strange javascript decoding behavior in IE

  - by Yoni

  I run the following html snippet in IE8 and IE7 with non-English characters (we tried both Hebrew and Chinese), and the second link never works properly. The displayed text in the alert box is mangled. This occurs in IE8 and IE7, but not in firefox. It is not dependent on Windows's regional settings. Here is the html snippet (html header and footer omitted for brevity, the content-type is "text/html; charset=utf-8", and so is the response header): <p> <a href="javascript:alert('ab????ab')">link with English and Hebrew text</a> <a href="javascript:alert('ab%D7%A9%D7%9C%D7%95%D7%9Dab')">same text, url encoded</a> </p> Here is the alert box that pops up when clicking the second link: I know that the string for "????" is encoded as 8 bytes in utf-8, thus there are 8 %NN items, and there are also 8 weird characters in the alert box. The problem is, how can I make IE recognize that this is utf-8 encoding text, like firefox does?

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• Simple continuously running XMPP client in python

  - by tom

  I'm using python-xmpp to send jabber messages. Everything works fine except that every time I want to send messages (every 15 minutes) I need to reconnect to the jabber server, and in the meantime the sending client is offline and cannot receive messages. So I want to write a really simple, indefinitely running xmpp client, that is online the whole time and can send (and receive) messages when required. My trivial (non-working) approach: import time import xmpp class Jabber(object): def __init__(self): server = 'example.com' username = 'bot' passwd = 'password' self.client = xmpp.Client(server) self.client.connect(server=(server, 5222)) self.client.auth(username, passwd, 'bot') self.client.sendInitPresence() self.sleep() def sleep(self): self.awake = False delay = 1 while not self.awake: time.sleep(delay) def wake(self): self.awake = True def auth(self, jid): self.client.getRoster().Authorize(jid) self.sleep() def send(self, jid, msg): message = xmpp.Message(jid, msg) message.setAttr('type', 'chat') self.client.send(message) self.sleep() if __name__ == '__main__': j = Jabber() time.sleep(3) j.wake() j.send('[email protected]', 'hello world') time.sleep(30) The problem here seems to be that I cannot wake it up. My best guess is that I need some kind of concurrency. Is that true, and if so how would I best go about that? EDIT: After looking into all the options concerning concurrency, I decided to go with twisted and wokkel. If I could, I would delete this post.

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• TSQL - make a literal float value

  - by David B

  I understand the host of issues in comparing floats, and lament their use in this case - but I'm not the table author and have only a small hurdle to climb... Someone has decided to use floats as you'd expect GUIDs to be used. I need to retrieve all the records with a specific float value. sp_help MyTable -- Column_name Type Computed Length Prec -- RandomGrouping float no 8 53 Here's my naive attempt: --yields no results SELECT RandomGrouping FROM MyTable WHERE RandomGrouping = 0.867153569942739 And here's an approximately working attempt: --yields 2 records SELECT RandomGrouping FROM MyTable WHERE RandomGrouping BETWEEN 0.867153569942739 - 0.00000001 AND 0.867153569942739 + 0.00000001 -- 0.867153569942739 -- 0.867153569942739 In my naive attempt, is that literal a floating point literal? Or is it really a decimal literal that gets converted later? If my literal is not a floating point literal, what is the syntax for making a floating point literal? EDIT: Another possibility has occurred to me... it may be that a more precise number than is displayed is stored in this column. It may be impossible to create a literal that represents this number. I will accept answers that demonstrate that this is the case. EDIT: response to DVK. TSQL is MSSQLServer's dialect of SQL. This script works, and so equality can be performed deterministically between float types: DECLARE @X float SELECT top 1 @X = RandomGrouping FROM MyTable WHERE RandomGrouping BETWEEN 0.839110948199148 - 0.000000000001 AND 0.839110948199148 + 0.000000000001 --yields two records SELECT * FROM MyTable WHERE RandomGrouping = @X I said "approximately" because that method tests for a range. With that method I could get values that are not equal to my intended value. The linked article doesn't apply because I'm not (intentionally) trying to straddle the world boundaries between decimal and float. I'm trying to work with only floats. This isn't about the non-convertibility of decimals to floats.

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• Server side form validation and POST data

  - by tomcritchlow

  Hi, I have a user input form here: http://www.7bks.com/create (Google login required) When you first create a list you are asked to create a public username. Unfortuantely currently there is no constraint to make this unique. I'm working on the code to enforce unique usernames at the moment and would like to know the best way to do it. Tech details: appengine, python, webapp framework What I'm planning is something like this: first the /create form posts the data to /inputlist/ (this is the same as currently happens) /inputlist/ queries the datastore for the given username. If it already exists then redirect back to /create display the /create page with all the info previously but with an additional error message of "this username is already taken" My question is: Is this the best way of handling server side validation? What's the best way of storing the list details while I verify and modify the username? As I see it I have 3 options to store the list details but I'm not sure which is "best": Store the list details in the session cookie (I am using GAEsessions for cookies) Define a separate POST class for /create and post the list data back from /inputlist/ to the /create page (currently /create only has a GET class) Store the list in the datastore, even though the username is non-unique. Thank you very much for your help :) I'm pretty new to python and coding in general so if I've missed something obvious my apologies. Tom PS - I'm sure I can eventually figure it out but I can't find any documentation on POSTing data using the webapp appengine framework which I'd need in order to do solution 2 above :s maybe you could point me in the right direction for that too? Thanks! PPS - It's a little out of date now but you can see roughly how the /create and /inputlist/ code works at the moment here: 7bks.com Gist

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• Is there a way to toggle bluetooth and/or wifi on and off programatically in iOS?

  - by Andy W

  I am looking for an easy way to toggle both bluetooth and wifi between on and off states on iOS 4.x devices (iPhone and iPad). I am constantly toggling these functions as I move between different locations and usage scenarios, and right now it takes multiple taps and visits to the Settings App. I am looking to create a simple App, that lives on Springboard, that I can just tap and it will turn off the wifi if it's on, and vice versa, then immediately quit. Similarly with an App for toggling bluetooth’s state. I have the developer SDK, and am comfortable in Xcode and with iOS development, so am happy to write the required Xcode to create the App. I am just at a loss as to which API, private or not, has the required functionality to simply toggle the state of these facilities. Because this is scratching a very personal itch, I have no intent to try and sell the App or get it up on the App store, so conforming with App guidelines on API usage is a non-issue. What I don’t want to do is jailbreak the devices, as I want to keep the core software as shipped. Can anyone point me at some sample code or more info on achieving this goal, as my Google-fu is letting me down, and if the information is out there for 4.x devices I just can’t find it.

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• Code-Golf: one line PHP syntax

  - by Kendall Hopkins

  Explanation PHP has some holes in its' syntax and occasionally in development a programmer will step in them. This can lead to much frustration as these syntax holes seem to exist for no reason. For example, one can't easily create an array and access an arbitrary element of that array on the same line (func1()[100] is not valid PHP syntax). The workaround for this issue is to use a temporary variable and break the statement into two lines, but sometimes that can lead to very verbose, clunky code. Challenge I know of a few of these holes (I'm sure there are more). It is quite hard to even come up with a solution, let alone in a code-golf style. Winner is the person with in the least characters total for all four Syntax Holes. Rules Statement must be one line in this form: $output = ...;, where ... doesn't contain any ;'s. Only use standard library functions (no custom functions allowed) Statement works identically to the assumed functional of the non-working syntax (even in cases that it fails). Statement must run without syntax error of any kind with E_STRICT | E_ALL. Syntax Holes $output = func_return_array()[$key]; - accessing an arbitrary offset (string or integer) of the returned array of a function $output = new {$class_base.$class_suffix}(); - arbitrary string concatenation being used to create a new class $output = {$func_base.$func_suffix}(); - arbitrary string concatenation being called as function $output = func_return_closure()(); - call a closure being returned from another function

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• Does running IIS7 in classic mode affect MVC output caching?

  - by Bob

  I have a need to run an application in classic mode for backwards compatibility with a specific application, and am trying to understand what kind of impact that will have on the performance of an MVC application that is running on the site. If we put a few static file maps (for .js, .css, .png, etc) above the ASP.NET wildcard map to reduce the amount of processing by the ASP.NET handler, will we be approaching the integrated mode in terms of performance? The thing i'm primarily concerned with is any effect this might have on output caching. I understand that integrated mode might (?) allow for the output cache to handle non ASP.NET content, but that isn't really a concern. We're more interested in ensuring that the MVC application has full use of the output cache. Empirically i've found that the two configurations operate on par when things go well, but if the page references resources that are not available, the integrated mode tends to fail much more quickly than the classic mode (e.g. 500 ms vs 10 seconds), reducing 'hang time' on the page load. Thanks for any feedback.

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• Returning large collections from WCF Serivce

  - by Nate Bross

  I'm trying to determine the best approach for building a WCF Service, and the area I'm struggling with most is returning lists of objects. The built-in maxMessageSize of 64k seems pretty high, and I really don't want to bump it up (quick googling finds 100s of places bumping the maxMessageSize up to multi-gigabyte range which seems foolish). But, when I'm returning a collection of objects (~150 items) I am exceeding the default 64k. I'm almost to the point of returning my own class which inherits IEnumerable and has properties for hasNext, hasPrevious and PageSize so that I can implement paging on the client side -- this seems like alot of code. The other option is to jackup the maxMessageSize and hope for the best, but that feels wrong. All other aspects of my service are working great, its just returning large collectiosn where I'm having issues. For background, there are two types of consumers of this service, UI applications which will be primarly web and/or wpf applications, and data processing applications, .NET console apps, and maybe some other non-UI apps. For the UI applications, I would like to keep them responsive and keep the messageSize low, on the console apps it doesn't matter as much as they are just pulling data down to do processing and push it back up to the service.

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• How do I set up FirePHP version 1.0?

  - by jay

  I love FirePHP and I've been using it for a while, but they've put out this massive upgrade and I'm completely flummoxed trying to get it to work. I think I'm copying the "Quick Start" code (kind of guessing at whatever changes are necessary for my server configuration), but for some reason, FirePHP's "primary" function, FirePHP::to() isn't doing anything. Can anyone please help me figure out what I'm doing wrong? Thanks. <?php define('INSIGHT_IPS', '*'); define('INSIGHT_AUTHKEYS', '290AA9215205F24E5104F48D61B60FFC'); define('INSIGHT_PATHS', __DIR__); define('INSIGHT_SERVER_PATH', '/doc_root/hello_firephp2.php'); set_include_path(get_include_path . ":/home8/jayharri/php/FirePHP/lib"); // path to FirePHP library require_once('FirePHP/Init.php'); $inpector = FirePHP::to('page'); var_dump($inspector); $console = $inspector->console(); $console->log('hello firephp'); ?> Output: NULL Fatal error: Call to a member function console() on a non-object in /home8/jayharri/public_html/if/doc_root/hello_firephp2.php on line 14

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• Java webapp: how to implement a web bug (1x1 pixel)?

  - by NoozNooz42

  In the accepted answer in the following question, a SO regular with 13K+ rep suggests to use a "web bug" (non-cacheable 1x1 img) to be able to track requests in the logs: http://stackoverflow.com/questions/1784893 How can I do this in Java? Basically, I've got two issues: how to make sure the 1x1 image is not cacheable (how to set the header)? how to make sure the query for these 1x1 image will appear in the logs? I'm looking for exact piece of code because I know how to write a .jsp/servlet and I know how to serve an 1x1 image :) My question is really about the exact .jsp/servlet that I should write and how/what needs to be done so that Tomcat logs the request. For example I plan to use the following mapping: <servlet-mapping> <servlet-name>WebBugServlet</servlet-name> <url-pattern>/webbug*</url-pattern> </servlet-mapping> and then use an img tag referencing a "webbug.png" (or .gif), so how do I write the .jsp/servlet? What/where should I look for in the logs?

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• how to multithread on a python server

  - by user3732790

  HELP please i have this code import socket from threading import * import time HOST = '' # Symbolic name meaning all available interfaces PORT = 8888 # Arbitrary non-privileged port s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) print ('Socket created') s.bind((HOST, PORT)) print ('Socket bind complete') s.listen(10) print ('Socket now listening') def listen(conn): odata = "" end = 'end' while end == 'end': data = conn.recv(1024) if data != odata: odata = data print(data) if data == b'end': end = "" print("conection ended") conn.close() while True: time.sleep(1) conn, addr = s.accept() print ('Connected with ' + addr[0] + ':' + str(addr[1])) Thread.start_new_thread(listen,(conn)) and i would like it so that when ever a person comes onto the server it has its own thread. but i can't get it to work please someone help me. :_( here is the error code: Socket created Socket bind complete Socket now listening Connected with 127.0.0.1:61475 Traceback (most recent call last): File "C:\Users\Myles\Desktop\test recever - Copy.py", line 29, in <module> Thread.start_new_thread(listen,(conn)) AttributeError: type object 'Thread' has no attribute 'start_new_thread' i am on python version 3.4.0 and here is the users code: import socket #for sockets import time s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) print('Socket Created') host = 'localhost' port = 8888 remote_ip = socket.gethostbyname( host ) print('Ip address of ' + host + ' is ' + remote_ip) #Connect to remote server s.connect((remote_ip , port)) print ('Socket Connected to ' + host + ' on ip ' + remote_ip) while True: message = input("> ") #Set the whole string s.send(message.encode('utf-8')) print ('Message send successfully') data = s.recv(1024) print(data) s.close

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• loading google maps drawing manager object

  - by psychok7

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

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• Hiding/blocking tabs using windows forms in c#

  - by Audel

  The thing is that i have a 'log in window' and a 'mainwindow' that is called after pressing the log in button or the "VISITANT" button If pressing the log in button, the whole system will come out, and if i press the VISITANT button, one tab should disappear or be blocked or something. private void visitant(object sender, EventArgs e) { mainwindow menu = new mainwindow(); menu.Show(); //mainwindow.tabPage1.Enabled = false; //attempt1 //mainwindow.tabPage1.Visible = false; //attempt1 //System.Windows.Forms.tabPage1.Enabled = false;//attempt2 //System.Windows.Forms.tabPage1.Visible = false;//attempt2 this.Hide(); } the errors i get for using the attempt1 are Error 1 'System.mainwindow.tabPage1' is inaccessible due to its protection level' Error 2 An object reference is required for the non-static field, method, or property 'System.mainwindow.tabPage1' and the one i get for using the attempt2 is Error 1 The type or namespace name 'tabPage1' does not exist in the namespace 'System.Windows.Forms' (are you missing an assembly reference?) as you probably have guessed "tabPage1" is the tab i need to hide when pressing the visitant button. I can't think of any more details, I will be around to provide any extra information Thanks in advance.

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• using volatile keyword

  - by sap

  As i understand, if we declare a variable as volatile, then it will not be stored in the local cache. Whenever thread are updating the values, it is updated to the main memory. So, other threads can access the updated value. But in the following program both volatile and non-volatile variables are displaying same value. The volatile variable is not updated for the second thread. Can anybody plz explain this why testValue is not changed. class ExampleThread extends Thread { private int testValue1; private volatile int testValue; public ExampleThread(String str){ super(str); } public void run() { if (getName().equals("Thread 1 ")) { testValue = 10; testValue1= 10; System.out.println( "Thread 1 testValue1 : " + testValue1); System.out.println( "Thread 1 testValue : " + testValue); } if (getName().equals("Thread 2 ")) { System.out.println( "Thread 2 testValue1 : " + testValue1); System.out.println( "Thread 2 testValue : " + testValue); } } } public class VolatileExample { public static void main(String args[]) { new ExampleThread("Thread 1 ").start(); new ExampleThread("Thread 2 ").start(); } } output: Thread 1 testValue1 : 10 Thread 1 testValue : 10 Thread 2 testValue1 : 0 Thread 2 testValue : 0

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• Java Random Slowdowns on Mac OS cont'd

  - by javajustice

  I asked this question a few weeks ago, but I'm still having the problem and I have some new hints. The original question is here: http://stackoverflow.com/questions/1651887/java-random-slowdowns-on-mac-os Basically, I have a java application that splits a job into independent pieces and runs them in separate threads. The threads have no synchronization or shared memory items. The only resources they do share are data files on the hard disk, with each thread having an open file channel. Most of the time it runs very fast, but occasionally it will run very slow for no apparent reason. If I attach a CPU profiler to it, then it will start running quickly again. If I take a CPU snapshot, it says its spending most of its time in "self time" in a function that doesn't do anything except check a few (unshared unsynchronized) booleans. I don't know how this could be accurate because 1, it makes no sense, and 2, attaching the profiler seems to knock the threads out of whatever mode they're in and fix the problem. Also, regardless of whether it runs fast or slow, it always finishes and gives the same output, and it never dips in total cpu usage (in this case ~1500%), implying that the threads aren't getting blocked. I have tried different garbage collectors, different sizings the parts of the memory space, writing data output to non-raid drives, and putting all data output in threads separate the main worker threads. Does anyone have any idea what kind of problem this could be? Could it be the operating system (OS X 10.6.2) ? I have not been able to duplicate it on a windows machine, but I don't have one with a similar hardware configuration.

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• Alternative way of implementation of a code

  - by vikramjb

  The title is not exactly meaningful, but I am not share what else to name it. I wrote a TOC Generation code sometime later. Based on this I was writing code to check for duplicates also. The code is as follows curNumber = getTOCReference(selItem.SNo, IsParent); CheckForDuplicates(curNumber, IsParent,out realTOCRef); curNumber = realTOCRef; And the code for CheckForDuplicates is ListViewItem curItem = this.tlvItems.FindItemWithText(curNumber); if (curItem != null) { curNumber = this.getTOCReference(curNumber, !IsParent); CheckForDuplicates(curNumber, IsParent,out realTOCRef); } else { realTOCRef= curNumber; } What this code does, it gets a TOC and tries it find if it already exists in the ObjectListView and gets a new TOC if there is a existing TOC. Once it determines that the generated TOC is not there in the list it stores it in realTOCRef and sends it back to the main calling code. I have used "out" to return the last generated TOC, which is something I did not want to do. The reason why I did it was after the non duplicate TOC was generated the return was not going back to the calling code instead it looped through the previous instances then it returned back. When the looping back happened the TOC that was to be returned also got reset. I would appreciate any help on this.

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• sharing message object between web applications

  - by jezhilvalan

  I need to share java mail message objects between two web applications(A and B). WebApplication A obtains the message and write it to the outputStream for(int i=0;i<messagesArr.length;i++){ uid = pop3FolderObj.getUID(messagesArr[i]); //storing messages with uid names inorder to maintain uniqueness File f = new File("F:/PersistedMessagesFolder" + uid); FileOutputStream fos = new FileOutputStream(f); messagesArr[i].writeTo(fos); fos.flush(); fos.close(); } Is FileOutputStream the best output stream for persisting message objects? Is it possible to use ObjectOutputStream for message object persistence? WebApplication B reads the message object via InputStream FileInputStream fis = new FileInputStream("F:/MessagesPersistedFolder"+uid); MimeMessage mm = new MimeMessage(sessionObj,fis); What if the mail message object which is already written via WebApplication A is not a MimeMessage? How can I read non-mime messages using input stream? MimeMessage constructor mandates sessionObj as the first parameter? How can I obtain this sessionObj in WebApplicationB? Do I have to again establish store connection with the same emailid,emailpassword,popserver and port(already used in WebApplication A) with the email server inorder to obtain this session object? Even if obtained, will this session object remains the same as that of the session object which is priorly obtained in WebApplicationA? Since I am using uids to name Message objects (inorder to maintain uniqueness of file names) how can I share these uids between WebApplication A and WebApplication B? WebApplication B needs the uid inorder to access the specific file which is present in "F:/MessagesPersistedFolder" Please help me in resolving the aforeseen issues.

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• Find the Algorithm that generates the checksum

  - by knivmannen

  I have a sensing device that transmits a 6-byte message along with an 1-byte counter and supposely a checksum. The data looks something like this: ------DATA----------- -Counter- --Checksum?-- 55 FF 00 00 EC FF ---- 60---------- 1F The last four bits in the counter are always set 0, i.e those bits are probably not used. The last byte is assumed to be the checksum since it has a quite peculiar nature. It tends to randomly change as data changes. Now what i need is to find the algorithm to compute this checksum based on --DATA--. what i have tried is all possible CRC-8 polynomials, for each polynomial i have tried to reflect data, toggle it, initiate it with non-zeroes etc etc. Ive come to the conclusion that i am not dealing with a normal crc-algorithm. I have also tried some flether and adler methods without succes, xor stuff back and forth but still i have no clue how to generate the checksum. My biggest concern is, how is the counter used??? Same data but with different countervalue generates different checksums. I have tried to include the counter in my computations but without any luck. Here are some other datasamples: 55 FF 00 00 F0 FF A0 38 66 0B EA FF BF FF C0 CA 5E 18 EA FF B7 FF 60 BD F6 30 16 00 FC FE 10 81 One more thing that might be worth mentioning is that the last byte in the data only takes on the values FF or FE Plz if u have any tips or tricks that i may try post them here, I am truly desperate. Thx

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• Fastest way to modify a decimal-keyed table in MySQL?

  - by javanix

  I am dealing with a MySQL table here that is keyed in a somewhat unfortunate way. Instead of using an auto increment table as a key, it uses a column of decimals to preserve order (presumably so its not too difficult to insert new rows while preserving a primary key and order). Before I go through and redo this table to something more sane, I need to figure out how to rekey it without breaking everything. What I would like to do is something that takes a list of doubles (the current keys) and outputs a list of integers (which can be cast down to doubles for rekeying). For example, input {1.00, 2.00, 2.50, 2.60, 3.00} would give output {1, 2, 3, 4, 5). Since this is a database, I also need to be able to update the rows nicely: UPDATE table SET `key`='3.00' WHERE `key`='2.50'; Can anyone think of a speedy algorithm to do this? My current thought is to read all of the doubles into a vector, take the size of the vector, and output a new vector with values from 1 => doubleVector.size. This seems pretty slow, since you wouldn't want to read every value into the vector if, for instance, only the last n/100 elements needed to be modified. I think there is probably something I can do in place, since only values after the first non-integer double need to be modified, but I can't for the life of me figure anything out that would let me update in place as well. For instance, setting 2.60 to 3.00 the first time you see 2.50 in the original key list would result in an error, since the key value 3.00 is already used for the table.

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• With NHibernate and Transaction do I rollback on commit failure or does it auto rollback on single c

  - by mattcodes

  I've built the following Dispose method for my Unit Of Work which essentially wraps the active NH session & transaction (transaction set as variable after opening session as to not be replaced if NH session gets new transaction after error) public void Dispose() { Func<ITransaction,bool> transactionStateOkayFunc = trans => trans != null && trans.IsActive && !trans.WasRolledBack; try { if(transactionStateOkayFunc(this.transaction)) { if (HasErrored) { transaction.Rollback(); } else { try { transaction.Commit(); } catch (Exception) { if(transactionStateOkayFunc(transaction)) transaction.Rollback(); throw; } } } } finally { if(transaction != null) transaction.Dispose(); if(session.IsOpen) session.Close(); } I can't help feeling that code is a little bloated, will a transaction automatically rollback is a discrete Commit fails in the case of non-nested transactions? Will Commit or Rollback automatically Dipose the transaction? If not will Session.Close() automatically dispose the associated transaction?

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