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• Multi-part question about multi-threading, locks and multi-core processors (multi ^ 3)

  - by MusiGenesis

  I have a program with two methods. The first method takes two arrays as parameters, and performs an operation in which values from one array are conditionally written into the other, like so: void Blend(int[] dest, int[] src, int offset) { for (int i = 0; i < src.Length; i++) { int rdr = dest[i + offset]; dest[i + offset] = src[i] > rdr? src[i] : rdr; } } The second method creates two separate sets of int arrays and iterates through them such that each array of one set is Blended with each array from the other set, like so: void CrossBlend() { int[][] set1 = new int[150][75000]; // we'll pretend this actually compiles int[][] set2 = new int[25][10000]; // we'll pretend this actually compiles for (int i1 = 0; i1 < set1.Length; i1++) { for (int i2 = 0; i2 < set2.Length; i2++) { Blend(set1[i1], set2[i2], 0); // or any offset, doesn't matter } } } First question: Since this apporoach is an obvious candidate for parallelization, is it intrinsically thread-safe? It seems like no, since I can conceive a scenario (unlikely, I think) where one thread's changes are lost because a different threads ~simultaneous operation. If no, would this: void Blend(int[] dest, int[] src, int offset) { lock (dest) { for (int i = 0; i < src.Length; i++) { int rdr = dest[i + offset]; dest[i + offset] = src[i] > rdr? src[i] : rdr; } } } be an effective fix? Second question: If so, what would be the likely performance cost of using locks like this? I assume that with something like this, if a thread attempts to lock a destination array that is currently locked by another thread, the first thread would block until the lock was released instead of continuing to process something. Also, how much time does it actually take to acquire a lock? Nanosecond scale, or worse than that? Would this be a major issue in something like this? Third question: How would I best approach this problem in a multi-threaded way that would take advantage of multi-core processors (and this is based on the potentially wrong assumption that a multi-threaded solution would not speed up this operation on a single core processor)? I'm guessing that I would want to have one thread running per core, but I don't know if that's true.

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• How do I create a partial function with generics in scala?

  - by Matteo Caprari

  Hello. I'm trying to write a performance measurements library for Scala. My idea is to transparently 'mark' sections so that the execution time can be collected. Unfortunately I wasn't able to bend the compiler to my will. An admittedly contrived example of what I have in mind: // generate a timing function val myTimer = mkTimer('myTimer) // see how the timing function returns the right type depending on the // type of the function it is passed to it val act = actor { loop { receive { case 'Int => val calc = myTimer { (1 to 100000).sum } val result = calc + 10 // calc must be Int self reply (result) case 'String => val calc = myTimer { (1 to 100000).mkString } val result = calc + " String" // calc must be String self reply (result) } Now, this is the farthest I got: trait Timing { def time[T <: Any](name: Symbol)(op: => T) :T = { val start = System.nanoTime val result = op val elapsed = System.nanoTime - start println(name + ": " + elapsed) result } def mkTimer[T <: Any](name: Symbol) : (() => T) => () => T = { type c = () => T time(name)(_ : c) } } Using the time function directly works and the compiler correctly uses the return type of the anonymous function to type the 'time' function: val bigString = time('timerBigString) { (1 to 100000).mkString("-") } println (bigString) Great as it seems, this pattern has a number of shortcomings: forces the user to reuse the same symbol at each invocation makes it more difficult to do more advanced stuff like predefined project-level timers does not allow the library to initialize once a data structure for 'timerBigString So here it comes mkTimer, that would allow me to partially apply the time function and reuse it. I use mkTimer like this: val myTimer = mkTimer('aTimer) val myString= myTimer { (1 to 100000).mkString("-") } println (myString) But I get a compiler error: error: type mismatch; found : String required: () => Nothing (1 to 100000).mkString("-") I get the same error if I inline the currying: val timerBigString = time('timerBigString) _ val bigString = timerBigString { (1 to 100000).mkString("-") } println (bigString) This works if I do val timerBigString = time('timerBigString) (_: String), but this is not what I want. I'd like to defer typing of the partially applied function until application. I conclude that the compiler is deciding the return type of the partial function when I first create it, chosing "Nothing" because it can't make a better informed choice. So I guess what I'm looking for is a sort of late-binding of the partially applied function. Is there any way to do this? Or maybe is there a completely different path I could follow? Well, thanks for reading this far -teo

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• Handling Exceptions for ThreadPoolExecutor

  - by HonorGod

  I have the following code snippet that basically scans through the list of task that needs to be executed and each task is then given to the executor for execution. The JobExecutor intern creates another executor (for doing db stuff...reading and writing data to queue) and completes the task. JobExecutor returns a Future for the tasks submitted. When one of the task fails, I want to gracefully interrupt all the threads and shutdown the executor by catching all the exceptions. What changes do I need to do? public class DataMovingClass { private static final AtomicInteger uniqueId = new AtomicInteger(0); private static final ThreadLocal<Integer> uniqueNumber = new IDGenerator(); ThreadPoolExecutor threadPoolExecutor = null ; private List<Source> sources = new ArrayList<Source>(); private static class IDGenerator extends ThreadLocal<Integer> { @Override public Integer get() { return uniqueId.incrementAndGet(); } } public void init(){ // load sources list } public boolean execute() { boolean succcess = true ; threadPoolExecutor = new ThreadPoolExecutor(10,10, 10, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(1024), new ThreadFactory() { public Thread newThread(Runnable r) { Thread t = new Thread(r); t.setName("DataMigration-" + uniqueNumber.get()); return t; }// End method }, new ThreadPoolExecutor.CallerRunsPolicy()); List<Future<Boolean>> result = new ArrayList<Future<Boolean>>(); for (Source source : sources) { result.add(threadPoolExecutor.submit(new JobExecutor(source))); } for (Future<Boolean> jobDone : result) { try { if (!jobDone.get(100000, TimeUnit.SECONDS) && success) { // in case of successful DbWriterClass, we don't need to change // it. success = false; } } catch (Exception ex) { // handle exceptions } } } public class JobExecutor implements Callable<Boolean> { private ThreadPoolExecutor threadPoolExecutor ; Source jobSource ; public SourceJobExecutor(Source source) { this.jobSource = source; threadPoolExecutor = new ThreadPoolExecutor(10,10,10, TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(1024), new ThreadFactory() { public Thread newThread(Runnable r) { Thread t = new Thread(r); t.setName("Job Executor-" + uniqueNumber.get()); return t; }// End method }, new ThreadPoolExecutor.CallerRunsPolicy()); } public Boolean call() throws Exception { boolean status = true ; System.out.println("Starting Job = " + jobSource.getName()); try { // do the specified task ; }catch (InterruptedException intrEx) { logger.warn("InterruptedException", intrEx); status = false ; } catch(Exception e) { logger.fatal("Exception occurred while executing task "+jobSource.getName(),e); status = false ; } System.out.println("Ending Job = " + jobSource.getName()); return status ; } } }

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• TypeError #1009, XML and AS3

  - by VideoDnd

  My animation is advanced forward, but it's frozen. It throws a TypeError #1009. How do I get rid of this error and get it to play? ERROR TypeError: Error #1009: Cannot access a property or method of a null object reference. at _fla::MainTimeline/frame1() TypeError: Error #1009: Cannot access a property or method of a null object reference. at _fla::MainTimeline/incrementCounter() at flash.utils::Timer/_timerDispatch() at flash.utils::Timer/tick() download http://sandboxfun.weebly.com/ XML <?xml version="1.0" encoding="utf-8"?> <SESSION> <TIMER TITLE="speed">1000</TIMER> <COUNT TITLE="starting position">10000</COUNT> </SESSION> FLA //DynamicText 'Count' var timer:Timer = new Timer(10); var count:int = 0; var fcount:int = 0; timer.addEventListener(TimerEvent.TIMER, incrementCounter); timer.start(); function incrementCounter(event:TimerEvent) { count = myXML.COUNT.text(); count++; fcount=int(count*count/1000); mytext.text = formatCount(fcount); } function formatCount(i:int):String { var fraction:int = i % 100; var whole:int = i / 100; return ("0000000" + whole).substr(-7, 7) + "." + (fraction < 10 ? "0" + fraction : fraction); } //LOAD XML var myXML:XML; var myLoader:URLLoader = new URLLoader(); myLoader.load(new URLRequest("time.xml")); myLoader.addEventListener(Event.COMPLETE, processXML); /*------CHANGED TIMER VALUE WITH XML------*/ timer = new Timer( Number(myXML.TIMER.text()) ); //timer.start(); //PARSE XML function processXML(e:Event):void { myXML = new XML(e.target.data); trace(myXML.COUNT.text()); trace(myXML.TIMER.text()); } //var count:int = 0;//give it a value type /*------CHANGED COUNT VALUE WITH XML------*/ count = myXML.COUNT.text();

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• Text to Speech in ASP.NET - Access is denied... what to do?

  - by Magnetic_dud

  On my personal website, i would like to make it "pronounce" something I solved the "concept" problem, as in here, and on my desktop it works smoothly when launched from visual web developer. Creates a file, and then an embedded player in the page will play it. Perfect. So, I uploaded it on the server... I get this error 500: Server Error in '/sapi' Application. Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)) Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED)) ASP.NET is not authorized to access the requested resource. Consider granting access rights to the resource to the ASP.NET request identity. ASP.NET has a base process identity (typically {MACHINE}\ASPNET on IIS 5 or Network Service on IIS 6) that is used if the application is not impersonating. If the application is impersonating via , the identity will be the anonymous user (typically IUSR_MACHINENAME) or the authenticated request user. (...) Source Error: See it below Source File: c:\mypath\sapi\myfile.aspx.cs Line: 21 Stack Trace: [UnauthorizedAccessException: Access is denied. (Exception from HRESULT: 0x80070005 (E_ACCESSDENIED))] SpeechLib.SpVoiceClass.Speak(String Text, SpeechVoiceSpeakFlags Flags) +0 prova.Button1_Click(Object sender, EventArgs e) in c:\mypath\sapi\prova.aspx.cs:21 System.Web.UI.WebControls.Button.OnClick(EventArgs e) +111 System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +110 System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10 System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13 System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1565 Version Information: Microsoft .NET Framework Version:2.0.50727.3053; ASP.NET Version:2.0.50727.3053 This is the source Source Error: Line 19: myfile.Open(@"C:\mypath\sapi\gen\hi.wav",SpeechStreamFileMode.SSFMCreateForWrite,false); Line 20: voice.AudioOutputStream = myfile; Line 21: voice.Speak("Hi",SpeechVoiceSpeakFlags.SVSFDefault); I get error on line 21, Voice.speak That probably means that the aspnet worker user has not some right permission The generation folder has all the right permissions: an empty file is created. So, i have to give permission of execute to some system dll? Do you know which dll? It is not bin\Interop.SpeechLib.dll, on this one the aspnet user has full control Ps: i have full control on the (windows) server (i mean, access by RDC, is not a shared hosting)

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• ASP Web Service Not Working

  - by BlitzPackage

  Good people, Hello. Our webservice is not working. We should be receiving information via an HTTP POST. However, nothing is working. Below are the code files. Let me know what you think. Thanks in advance for any help or information you can provide. (By the way, some information (e.g. class names, connection strings, etc...) has been removed or changed in order to hide any sensitive information. Imports System.Web.Mail Imports System.Data Imports System.Data.SqlClient Imports System.IO Partial Class hbcertification Inherits System.Web.UI.Page Public strBody As String = "" Public sqlInsertStr As String = "" Public errStr As String = "" Public txn_id, first_name, last_name, address_street, address_city, address_state, address_zip, address_country, address_phone, payer_email, Price, key, invoice, payment_date, mc_fee, buyer_ip As String Dim myConn As New SqlConnection(ConfigurationSettings.AppSettings("ConnectionInfo")) '******************************************************************************************* Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load strBody += "Test email sent.Customer name: " & Request("first_name") & " " & Request("last_name") strBody += "Reg Key: " & Request("key") & "Transaction ID: " & Request("txn_id") & "Tran Type: " & Request("txn_type") updateFile(Server.MapPath("log.txt"), strBody) txn_id = Request("txn_id") first_name = Request("first_name") last_name = Request("last_name") address_street = Request("address_street") address_city = Request("address_city") address_state = Request("address_state") address_zip = Request("address_zip") address_country = Request("address_country") address_phone = Request("address_phone") payer_email = Request("payer_email") Price = Request("Price") key = Request("key") invoice = Request("invoice") payment_date = Request("payment_date") mc_fee = Request("mc_fee") buyer_ip = Request("buyer_ip") If Request("first_name") "" And Request("last_name") "" Then SendMail("[email protected]", "[email protected]", strBody, "Software Order Notification", "[email protected]") Else Response.Write("Email not sent. Name missing.") End If Dim sItem As String Response.Write("") If Request.Form("dosubmit") = "1" Then Response.Write("FORM VALS:") For Each sItem In Request.Form Response.Write("" & sItem & " - [" & Request.Form(sItem) & "]") Next sqlInsertStr += "insert into aspnet_MorrisCustomerInfo (TransactionID,FirstName,LastName,AddressStreet,AddressCity,AddressState,AddressZip,AddressCountry,AddressPhone,PayerEmail,Price,AuthenticationCode,InvoiceID,PurchaseDate,PaypalFee,PurchaseIPAddress) values ('" & SQLSafe(txn_id) & "','" & SQLSafe(first_name) & "','" & SQLSafe(last_name) & "','" & SQLSafe(address_street) & "','" & SQLSafe(address_city) & "','" & SQLSafe(address_state) & "','" & SQLSafe(address_zip) & "','" & SQLSafe(address_country) & "','" & SQLSafe(address_phone) & "','" & SQLSafe(payer_email) & "','" & SQLSafe(Price) & "','" & SQLSafe(key) & "','" & SQLSafe(invoice) & "','" & SQLSafe(payment_date) & "','" & SQLSafe(mc_fee) & "','" & SQLSafe(buyer_ip) & "')" runMyQuery(sqlInsertStr, False) End If Response.Write("sqlInsertStr is: " & sqlInsertStr) Response.Write("") End Sub '******************************************************************************************* Sub SendMail(ByVal strEmailAddress, ByVal strEmailAddress_cc, ByVal Email_Body, ByVal Email_Subject, ByVal Email_From) If Request.ServerVariables("server_name") "localhost" Then Try Dim resumeEmail As New MailMessage resumeEmail.To = strEmailAddress resumeEmail.Cc = strEmailAddress_cc resumeEmail.From = Email_From resumeEmail.Subject = Email_Subject resumeEmail.Priority = MailPriority.High 'resumeEmail.BodyFormat = MailFormat.Html resumeEmail.BodyFormat = MailFormat.Html resumeEmail.Body = Email_Body 'System.Web.Mail.SmtpMail.SmtpServer = "morris.com" System.Web.Mail.SmtpMail.SmtpServer = "relay-hosting.secureserver.net" System.Web.Mail.SmtpMail.Send(resumeEmail) Response.Write("Email sent.") Catch exc As Exception Response.Write("MAIL ERROR OCCURRED" & exc.ToString() & "From: " & Email_From) End Try Else Response.Write("TEST RESPONSE" & strBody & "") End If End Sub End Function End Class Process Data Asp.Net Configuration option in Visual Studio. A full list of settings and comments can be found in machine.config.comments usually located in \Windows\Microsoft.Net\Framework\v2.x\Config -- section enables configuration of the security authentication mode used by ASP.NET to identify an incoming user. -- section enables configuration of what to do if/when an unhandled error occurs during the execution of a request. Specifically, it enables developers to configure html error pages to be displayed in place of a error stack trace. --

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• Why is Oracle using a skip scan for this query?

  - by Jason Baker

  Here's the tkprof output for a query that's running extremely slowly (WARNING: it's long :-) ): SELECT mbr_comment_idn, mbr_crt_dt, mbr_data_source, mbr_dol_bl_rmo_ind, mbr_dxcg_ctl_member, mbr_employment_start_dt, mbr_employment_term_dt, mbr_entity_active, mbr_ethnicity_idn, mbr_general_health_status_code, mbr_hand_dominant_code, mbr_hgt_feet, mbr_hgt_inches, mbr_highest_edu_level, mbr_insd_addr_idn, mbr_insd_alt_id, mbr_insd_name, mbr_insd_ssn_tin, mbr_is_smoker, mbr_is_vip, mbr_lmbr_first_name, mbr_lmbr_last_name, mbr_marital_status_cd, mbr_mbr_birth_dt, mbr_mbr_death_dt, mbr_mbr_expired, mbr_mbr_first_name, mbr_mbr_gender_cd, mbr_mbr_idn, mbr_mbr_ins_type, mbr_mbr_isreadonly, mbr_mbr_last_name, mbr_mbr_middle_name, mbr_mbr_name, mbr_mbr_status_idn, mbr_mpi_id, mbr_preferred_am_pm, mbr_preferred_time, mbr_prv_innetwork, mbr_rep_addr_idn, mbr_rep_name, mbr_rp_mbr_id, mbr_same_mbr_ins, mbr_special_needs_cd, mbr_timezone, mbr_upd_dt, mbr_user_idn, mbr_wgt, mbr_work_status_idn FROM (SELECT /*+ FIRST_ROWS(1) */ mbr_comment_idn, mbr_crt_dt, mbr_data_source, mbr_dol_bl_rmo_ind, mbr_dxcg_ctl_member, mbr_employment_start_dt, mbr_employment_term_dt, mbr_entity_active, mbr_ethnicity_idn, mbr_general_health_status_code, mbr_hand_dominant_code, mbr_hgt_feet, mbr_hgt_inches, mbr_highest_edu_level, mbr_insd_addr_idn, mbr_insd_alt_id, mbr_insd_name, mbr_insd_ssn_tin, mbr_is_smoker, mbr_is_vip, mbr_lmbr_first_name, mbr_lmbr_last_name, mbr_marital_status_cd, mbr_mbr_birth_dt, mbr_mbr_death_dt, mbr_mbr_expired, mbr_mbr_first_name, mbr_mbr_gender_cd, mbr_mbr_idn, mbr_mbr_ins_type, mbr_mbr_isreadonly, mbr_mbr_last_name, mbr_mbr_middle_name, mbr_mbr_name, mbr_mbr_status_idn, mbr_mpi_id, mbr_preferred_am_pm, mbr_preferred_time, mbr_prv_innetwork, mbr_rep_addr_idn, mbr_rep_name, mbr_rp_mbr_id, mbr_same_mbr_ins, mbr_special_needs_cd, mbr_timezone, mbr_upd_dt, mbr_user_idn, mbr_wgt, mbr_work_status_idn, ROWNUM AS ora_rn FROM (SELECT mbr.comment_idn AS mbr_comment_idn, mbr.crt_dt AS mbr_crt_dt, mbr.data_source AS mbr_data_source, mbr.dol_bl_rmo_ind AS mbr_dol_bl_rmo_ind, mbr.dxcg_ctl_member AS mbr_dxcg_ctl_member, mbr.employment_start_dt AS mbr_employment_start_dt, mbr.employment_term_dt AS mbr_employment_term_dt, mbr.entity_active AS mbr_entity_active, mbr.ethnicity_idn AS mbr_ethnicity_idn, mbr.general_health_status_code AS mbr_general_health_status_code, mbr.hand_dominant_code AS mbr_hand_dominant_code, mbr.hgt_feet AS mbr_hgt_feet, mbr.hgt_inches AS mbr_hgt_inches, mbr.highest_edu_level AS mbr_highest_edu_level, mbr.insd_addr_idn AS mbr_insd_addr_idn, mbr.insd_alt_id AS mbr_insd_alt_id, mbr.insd_name AS mbr_insd_name, mbr.insd_ssn_tin AS mbr_insd_ssn_tin, mbr.is_smoker AS mbr_is_smoker, mbr.is_vip AS mbr_is_vip, mbr.lmbr_first_name AS mbr_lmbr_first_name, mbr.lmbr_last_name AS mbr_lmbr_last_name, mbr.marital_status_cd AS mbr_marital_status_cd, mbr.mbr_birth_dt AS mbr_mbr_birth_dt, mbr.mbr_death_dt AS mbr_mbr_death_dt, mbr.mbr_expired AS mbr_mbr_expired, mbr.mbr_first_name AS mbr_mbr_first_name, mbr.mbr_gender_cd AS mbr_mbr_gender_cd, mbr.mbr_idn AS mbr_mbr_idn, mbr.mbr_ins_type AS mbr_mbr_ins_type, mbr.mbr_isreadonly AS mbr_mbr_isreadonly, mbr.mbr_last_name AS mbr_mbr_last_name, mbr.mbr_middle_name AS mbr_mbr_middle_name, mbr.mbr_name AS mbr_mbr_name, mbr.mbr_status_idn AS mbr_mbr_status_idn, mbr.mpi_id AS mbr_mpi_id, mbr.preferred_am_pm AS mbr_preferred_am_pm, mbr.preferred_time AS mbr_preferred_time, mbr.prv_innetwork AS mbr_prv_innetwork, mbr.rep_addr_idn AS mbr_rep_addr_idn, mbr.rep_name AS mbr_rep_name, mbr.rp_mbr_id AS mbr_rp_mbr_id, mbr.same_mbr_ins AS mbr_same_mbr_ins, mbr.special_needs_cd AS mbr_special_needs_cd, mbr.timezone AS mbr_timezone, mbr.upd_dt AS mbr_upd_dt, mbr.user_idn AS mbr_user_idn, mbr.wgt AS mbr_wgt, mbr.work_status_idn AS mbr_work_status_idn FROM mbr JOIN mbr_identfn ON mbr.mbr_idn = mbr_identfn.mbr_idn WHERE mbr_identfn.mbr_idn = mbr.mbr_idn AND mbr_identfn.identfd_type = :identfd_type_1 AND mbr_identfn.identfd_number = :identfd_number_1 AND mbr_identfn.entity_active = :entity_active_1) WHERE ROWNUM <= :ROWNUM_1) WHERE ora_rn > :ora_rn_1 call count cpu elapsed disk query current rows ------- ------ -------- ---------- ---------- ---------- ---------- ---------- Parse 9936 0.46 0.49 0 0 0 0 Execute 9936 0.60 0.59 0 0 0 0 Fetch 9936 329.87 404.00 0 136966922 0 0 ------- ------ -------- ---------- ---------- ---------- ---------- ---------- total 29808 330.94 405.09 0 136966922 0 0 Misses in library cache during parse: 0 Optimizer mode: FIRST_ROWS Parsing user id: 36 (JIVA_DEV) Rows Row Source Operation ------- --------------------------------------------------- 0 VIEW (cr=102 pr=0 pw=0 time=2180 us) 0 COUNT STOPKEY (cr=102 pr=0 pw=0 time=2163 us) 0 NESTED LOOPS (cr=102 pr=0 pw=0 time=2152 us) 0 INDEX SKIP SCAN IDX_MBR_IDENTFN (cr=102 pr=0 pw=0 time=2140 us)(object id 341053) 0 TABLE ACCESS BY INDEX ROWID MBR (cr=0 pr=0 pw=0 time=0 us) 0 INDEX UNIQUE SCAN PK_CLAIMANT (cr=0 pr=0 pw=0 time=0 us)(object id 334044) Rows Execution Plan ------- --------------------------------------------------- 0 SELECT STATEMENT MODE: HINT: FIRST_ROWS 0 VIEW 0 COUNT (STOPKEY) 0 NESTED LOOPS 0 INDEX MODE: ANALYZED (SKIP SCAN) OF 'IDX_MBR_IDENTFN' (INDEX (UNIQUE)) 0 TABLE ACCESS MODE: ANALYZED (BY INDEX ROWID) OF 'MBR' (TABLE) 0 INDEX MODE: ANALYZED (UNIQUE SCAN) OF 'PK_CLAIMANT' (INDEX (UNIQUE)) ******************************************************************************** Based on my reading of Oracle's documentation of skip scans, a skip scan is most useful when the first column of an index has a low number of unique values. The thing is that the first index of this column is a unique primary key. So am I correct in assuming that a skip scan is the wrong thing to do here? Also, what kind of scan should it be doing? Should I do some more hinting for this query? EDIT: I should also point out that the query's where clause uses the columns in IDX_MBR_IDENTFN and no columns other than what's in that index. So as far as I can tell, I'm not skipping any columns.

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• Jquery Cycle issue or css issue in Chrome/Safari for Mac

  - by Mark

  Hi i have used the jquery cycle plugin to create multiple simple sliding galleries. In Chrome/Safair on Mac the browser is not loading the images. Here is the link the js i am using is here, although it could be a css issue..? I am struggling to find the real problem. $(document).ready(function() { $('.slides').each(function() { var $this = $(this), $ss = $this.closest('.slideshow'); var prev = $ss.find('a.prev'), next = $ss.find('a.next'); $this.cycle({ prev: prev, next: next, fx: 'scrollLeft', speed: 'fast', timeout: 0 }); }); }); CSS .slideshow { width:476px; height:287px; float:left; margin-right:30px; position:relative; z-index:0; margin-bottom:20px; } .slides { position:absolute; top:0; left:0; z-index:1; } a.prev { display:block; width:23px; height:22px; background:red; position:absolute; z-index:1000; background: url(../images/next_prev.png) no-repeat 0 0; top:133px; left:-11px; } a.next { display:block; width:23px; height:22px; background:red; position:absolute; z-index:1000; background: url(../images/next_prev.png) no-repeat -23px 0; top:133px; right:-11px; } Markup: <div class="slideshow"> <div class="slides"> <img src="images/chief_st_1.jpg" alt="CHIEF stationery + literature" /> <img src="images/chief_st_3.jpg" alt="CHIEF stationery + literature" /> <img src="images/chief_st_2.jpg" alt="CHIEF stationery + literature" /> </div> <a class="prev" href="#"></a> <a class="next" href="#"></a> </div> Any help would be appreciated. thanks

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• How can I easily maintain a cross-file JavaScript Library Development Environment

  - by John

  I have been developing a new JavaScript application which is rapidly growing in size. My entire JavaScript Application has been encapsulated inside a single function, in a single file, in a way like this: (function(){ var uniqueApplication = window.uniqueApplication = function(opts){ if (opts.featureOne) { this.featureOne = new featureOne(opts.featureOne); } if (opts.featureTwo) { this.featureTwo = new featureTwo(opts.featureTwo); } if (opts.featureThree) { this.featureThree = new featureThree(opts.featureThree); } }; var featureOne = function(options) { this.options = options; }; featureOne.prototype.myFeatureBehavior = function() { //Lots of Behaviors }; var featureTwo = function(options) { this.options = options; }; featureTwo.prototype.myFeatureBehavior = function() { //Lots of Behaviors }; var featureThree = function(options) { this.options = options; }; featureThree.prototype.myFeatureBehavior = function() { //Lots of Behaviors }; })(); In the same file after the anonymous function and execution I do something like this: (function(){ var instanceOfApplication = new uniqueApplication({ featureOne:"dataSource", featureTwo:"drawingCanvas", featureThree:3540 }); })(); Before uploading this software online I pass my JavaScript file, and all it's dependencies, into Google Closure Compiler, using just the default Compression, and then I have one nice JavaScript file ready to go online for production. This technique has worked marvelously for me - as it has created only one global footprint in the DOM and has given me a very flexible framework to grow each additional feature of the application. However - I am reaching the point where I'd really rather not keep this entire application inside one JavaScript file. I'd like to move from having one large uniqueApplication.js file during development to having a separate file for each feature in the application, featureOne.js - featureTwo.js - featureThree.js Once I have completed offline development testing, I would then like to use something, perhaps Google Closure Compiler, to combine all of these files together - however I want these files to all be compiled inside of that scope, as they are when I have them inside one file - and I would like for them to remain in the same scope during offline testing too. I see that Google Closure Compiler supports an argument for passing in modules but I haven't really been able to find a whole lot of information on doing something like this. Anybody have any idea how this could be accomplished - or any suggestions on a development practice for writing a single JavaScript Library across multiple files that still only leaves one footprint on the DOM?

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• How to use ResourceManager in a "website" mode ?

  - by Erick

  I am trying here to do a manual translation for the application I am working with. (There is already a working LocalizationModule but it's working dodgy, so I can't use <asp:Localize /> tags. Normally with ResourceManager you are supposed to be using it as Namespace.Folder.Resourcename (in an application). Currently I am translating an existing asp.net "website" (not web application so no namespace here....). The resources are located into a folder name "Locales/resources" which contains "fr-ca.resx" and "en-us.resx". So I used a code with something like this : public static string T(string search) { System.Resources.ResourceManager resMan = new System.Resources.ResourceManager( "Locales", System.Reflection.Assembly.GetExecutingAssembly(), null ); var text = resMan.GetString(search, System.Threading.Thread.CurrentThread.CurrentCulture); if (text == null) return "null"; else if (text == string.Empty) return "empty"; else return text; } and inside the page I have something like this <%= Locale.T("T_HOME") %> When I refresh I have this : Could not find any resources appropriate for the specified culture or the neutral culture. Make sure "Locales.resources" was correctly embedded or linked into assembly "App_Code.9yopn1f7" at compile time, or that all the satellite assemblies required are loadable and fully signed. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.Resources.MissingManifestResourceException: Could not find any resources appropriate for the specified culture or the neutral culture. Make sure "Locales.resources" was correctly embedded or linked into assembly "App_Code.9yopn1f7" at compile time, or that all the satellite assemblies required are loadable and fully signed. Source Error: Line 14: System.Resources.ResourceManager resMan = new System.Resources.ResourceManager( "Locales", System.Reflection.Assembly.GetExecutingAssembly(), null ); Line 15: Line 16: var text = resMan.GetString(search, System.Threading.Thread.CurrentThread.CurrentCulture); Line 17: Line 18: if (text == null) Source File: c:\inetpub\vhosts\galerieocarre.com\subdomains\dev\httpdocs\App_Code\Locale.cs Line: 16 I even tried to load the resource with Locales.fr-ca or only fr-ca nothing quite work here.

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• Is it normal for a programmer with 2 years experience to take a long time to code simple programs?

  - by ajax81

  Hi all, I'm a relatively new programmer (18 months on the scene), and I'm finally getting to the point where I'm comfortable accepting projects and developing solutions under minimal supervision. Unfortunately, this also means that I've become acutely aware of my performance shortfalls, the most prevalent of which is the amount of time it takes me to develop, test, and submit algorithms for review. A great example of what I'm talking about occurred this week when I was tasked with developing a simple XML web service (asp.net 3.5) callable via client-side JavaScript, that accepts a single parameter and returns a dataset output to a modal window (please note this is the first time I've had to develop a web service and have had ZERO experience creating/consuming them...let alone calling them from JS client side). Keeping a long story short -- I worked on it for 4 days straight, all day each day, for a grand total of 36 hours, not including the time I spent dwelling on the problem in the shower, the morning commute, and laying awake in bed at night. I learned a great deal about web services and xml/json/javascript...but was called in for a management review to discuss the length of time it took me to develop the solution. In the meeting, I was praised for the quality of my work and was in fact told that my effort was commendable. However, they (senior leads and pm's) weren't impressed with the amount of time it took me to develop the solution and expressed that they would have liked to see the solution in roughly 1/3 of the time it took me. I guess what concerns me the most is that I've identified this pattern as common for myself. Between online videos, book research, and trial/error coding...if its something I haven't seen before, I can spend up to two weeks on a problem that seems to only take the pros in the videos moments to code up. And of course, knowing that management isn't happy with this pattern has shaken me up a bit. To sum up, I have some very specific questions I'd like to ask, and would greatly appreciate your objective professional feedback. Is my experience as a junior programmer common among new developers? Or is it possible that I'm just not cut out for the work? If you suspect that my experience is not common and that there may be an aptitude issue, do you have any suggestions/solutions that I could propose to management to help bring me up to speed? Do seasoned, professional programmers ever encounter knowledge barriers that considerably delay deliverables? When you started out in the industry, did you know how to "do it all"? If not, how long did it take you to be perceived as "proficient"? Was it a natural progression of trial and error, or was there a particular zen moment when you knew you had achieved super saiyen power level? Anyways, thanks for taking the time to read my question(s). I don't know if this is the right place to ask for professional career guidance, but I greatly appreciate your willingness to help me out. Cheers, Daniel

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• Jquery Automatic Image Slider w/ CSS & jQuery

  - by Jacinto

  This is Automatic Image Slider w/ CSS & jQuery by Soh Tanaka I am trying to customize it to show .desc when the mouse hover overs the slider but it does not seem to work any help? //Set Default State of each portfolio piece $(".paging").show(); $(".paging a:first").addClass("active"); //Get size of images, how many there are, then determin the size of the image reel. var imageWidth = $(".window").width(); var imageSum = $(".image_reel ul.examples").size(); var imageReelWidth = imageWidth * imageSum; //Adjust the image reel to its new size $(".image_reel").css({'width' : imageReelWidth}); //Paging + Slider Function rotate = function(){ var triggerID = $active.attr("rel") - 1; //Get number of times to slide var image_reelPosition = triggerID * imageWidth; //Determines the distance the image reel needs to slide $(".paging a").removeClass('active'); //Remove all active class $active.addClass('active'); //Add active class (the $active is declared in the rotateSwitch function) //Slider Animation $(".image_reel").animate({ left: -image_reelPosition }, 500 ); }; //Rotation + Timing Event rotateSwitch = function(){ play = setInterval(function(){ //Set timer - this will repeat itself every 3 seconds $active = $('.paging a.active').next(); if ( $active.length === 0) { //If paging reaches the end... $active = $('.paging a:first'); //go back to first } rotate(); //Trigger the paging and slider function }, 7000); //Timer speed in milliseconds (3 seconds) }; rotateSwitch(); //Run function on launch //On Hover $(".image_reel").hover(function() { clearInterval(play); //Stop the rotation }, function() { rotateSwitch(); //Resume rotation }); //Hide the tooglebox when page load $(".desc").hide(); //slide up and down when hover over heading 2 $(".image_reel").hover(function(){ // slide toggle effect set to slow you can set it to fast too. $(this).next(".desc").slideToggle("slow"); return true; }); //On Click $(".paging a").click(function() { $active = $(this); //Activate the clicked paging //Reset Timer clearInterval(play); //Stop the rotation rotate(); //Trigger rotation immediately rotateSwitch(); // Resume rotation return false; //Prevent browser jump to link anchor });

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• jPlayer widget created with static error as result

  - by goldengel

  I've created a widged with Orchard. Unfortunately I've used the same "Title" for a jPlayer widget twice. Now I receive an error: Server Error in '/wgk' Application. Sequence contains more than one element Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. Exception Details: System.InvalidOperationException: Sequence contains more than one element Source Error: Line 2: <fieldset> Line 3: <div>@Html.LabelFor(o => o.MediaGalleryName, @T("Media gallery"))</div> Line 4: @if(!Model.HasAvailableGalleries) { Line 5: <div>@T("You need first to create an media gallery on Media Gallery menu")</div> Line 6: } Source File: x:\Intepub\wgk\Modules\Orchard.jPlayer\Views\EditorTemplates\Parts\MediaGallery.cshtml Line: 4 Stack Trace: [InvalidOperationException: Sequence contains more than one element] System.Linq.Enumerable.SingleOrDefault(IEnumerable`1 source) +4206966 NHibernate.Linq.Visitors.ImmediateResultsVisitor`1.HandleSingleOrDefaultCall(MethodCallExpression call) +51 NHibernate.Linq.Visitors.ImmediateResultsVisitor`1.VisitMethodCall(MethodCallExpression call) +411 NHibernate.Linq.Visitors.ExpressionVisitor.Visit(Expression exp) +371 In MediaGallery.cshtml (found in error description above) is written: @model Orchard.jPlayer.Models.MediaGalleryPart <fieldset> <div>@Html.LabelFor(o => o.MediaGalleryName, @T("Media gallery"))</div> @if(!Model.HasAvailableGalleries) { <div>@T("You need first to create an media gallery on Media Gallery menu")</div> } else { <div>@Html.DropDownListFor(o => o.SelectedGallery, Model.AvailableGalleries)</div> <div>@Html.LabelFor(o => o.SelectedType, @T("Media gallery type"))</div> <div>@Html.DropDownListFor(o => o.SelectedType, Model.AvailableTypes)</div> <div>@Html.LabelFor(o => o.AutoPlay, @T("Auto play"))</div> <div>@Html.CheckBoxFor(o => o.AutoPlay)</div> } </fieldset> My problem is now, I cannot find or edit the widget with double used name. I would love to replace it to another name. But I do not know where to do this. Please advice.

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• TeamCity Scheduled Build not getting all files from VSS

  - by Kate

  Within TeamCity if I trigger a build it all works correctly, however if the Scheduler triggers a build it does not seem to get all the files from VSS. I have clean checkout directory turned on, so I am not sure how it determines the patch for the VSS root. Does anyone have any suggestions on how I can get it to always get all files, and create a new patch each time? I have put the start of two build logs below, as you can see the first one has the correct 249mb, whereas the second only transfers 2MB. The files it doesn't get from VSS seem sporadic and not in relation to what has changed. Manual Trigger [23:57:49]: Checking for changes [00:09:04]: Clean build enabled: removing old files from C:\Builds\Ab 2.0 [00:09:04]: Clearing temporary directory: C:\TeamCity\buildAgent\temp\buildTmp [00:09:05]: Checkout directory: C:\Builds\Ab 2.0 [00:09:05]: Updating sources: server side checkout... (24m:53s) [00:09:05]: [Updating sources: server side checkout...] Will perform clean checkout [00:09:05]: [Updating sources: server side checkout...] Clean checkout reasons [00:09:05]: [Clean checkout reasons] Checkout directory is empty or doesn't exist [00:09:05]: [Clean checkout reasons] "Clean all files before build" turned on [00:09:05]: [Updating sources: server side checkout...] Transferring cached clean patch for VCS root: Ab 2.0 [00:09:42]: [Updating sources: server side checkout...] Building incremental patch over the cached patch [00:31:50]: [Updating sources: server side checkout...] Transferring repository sources: 124.0Mb so far... [00:32:18]: [Updating sources: server side checkout...] Repository sources transferred: 249.46Mb total [00:32:18]: [Updating sources: server side checkout...] Average transfer speed: 183.40Kb per second Triggered by the Scheduler [07:45:01]: Checking for changes [07:55:09]: Clean build enabled: removing old files from C:\Builds\Ab 2.0 [07:55:22]: Clearing temporary directory: C:\TeamCity\buildAgent\temp\buildTmp [07:55:22]: Checkout directory: C:\Builds\Ab 2.0 [07:55:22]: Updating sources: server side checkout... (24m:24s) [07:55:22]: [Updating sources: server side checkout...] Will perform clean checkout [07:55:22]: [Updating sources: server side checkout...] Clean checkout reasons [07:55:22]: [Clean checkout reasons] Checkout directory is empty or doesn't exist [07:55:22]: [Clean checkout reasons] "Clean all files before build" turned on [07:55:22]: [Updating sources: server side checkout...] Building clean patch for VCS root: Ab 2.0 [08:19:46]: [Updating sources: server side checkout...] Transferring cached clean patch for VCS root: Ab 2.0 [08:19:47]: [Updating sources: server side checkout...] Repository sources transferred: 2.01Mb total

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• Upload large files via a webpage

  - by Hultner

  What way is the best way to let users upload large files from there webbrowser to a server. I'm talking 200MB+ possible up to a few gigatyes. I have been thinking of a few possible solutions to the problem (not tried them yet) and this is basically the things I came up with. Server download speed will not be a problem but the users connection possibly could. Having some sort of applet on the client side written in Java or Flash which sends the file in parts (is this possible with an applet) to a php/other script on the server and a checksum+ some other info about the file. On the server scripts all the parts and the info file is saved in a temporary directory wich has a unique name based on the checksum of the file and the ip of the user. When the last chunk is sent the applet sends a signal to the server saying it's finished and the server put the file together in the right location. If a chunk doesn't match the checksum for that part the server will send a response to the applet telling it to reupload that chunk. I don't know how important the checksum checking is since it's all tcpackages, someone with more insigth migth be able to answer on that. This is probably the worst way, changing the settings on your server to allow huge fileuploads via an inputfiel. Do it like a normal transfer. User an uploadmanager which does pretty much the same thing as applet i mentioned above. Pros of the first is probably that it would most likely be rather secure, you could show progress as well and possibly resume an upload if ip hasn't changed and do a threaded upload of the chunks. Cons of the first is that the user will need flash/java for it to work. Pros of the 2nd is that it will pretty much work for everyone but cons are big, first there's no way resuming an intruppted download and if something is wrong the whole file would have to be reuploaded is a few of cons. For the third one the pros is pretty muc the same as for the first but the cons is that the user would have to download an application to their computer and run and the application will have to be have to be compatible with their computer and OS. Another way may be a combination of two. Lets say an applet for bigger or more files and a simple input which is rather restricted to maybe max 10-20MB for smaller files and comability. There are probably other much smarter ways to tackle this and that's why I'm asking for advice here on SO.

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• Git/Mercurial (hg) opinion

  - by Richard

  First, let me say I'm not a professional programmer, but an engineer who had a need for it and had to learn. I was always working alone, so it was just me and my seven splitted personalities ... and we worked okey as a team :) Most of my stuff is done in C/Fortran/Matlab and so far I've been learning git to manage it all. However, although I've had no unsolvable problems with it, I've never been "that" happy with it ... for everything I cannot do, I hae to look up a book. And, for some time now I've been hearning a lot of good stuff about hg. Now, a coleague of mine will have to work with me on a project (I almost feel sorry for him) and he's started learning hg (says he likes it more), and I'm considering the switch myself. We work almost exclusivly on Windows platform (although I manage relatively ok using unix tools and things that come from that part of the world). So, I was wondering, in a described scenario, what problems could I expect with the switch. I heard that hg is rather more user friendly towards windows users, regarding the user interfaces. How does it handle repositories ? Does it create them the same way as git does (just one subdirectory in a working directory) and can I just copy the whole project directory (including git repo) and just carry them somewhere with no extra thinking ? (I really liked that when I was choosing over git/svn). Are there any good books on it that you can recommend (something like Pro Git, only for Hg). What are good ways to implement hg into Visual Studio/GVim for Windows, or into Windows Explorer so I can work relatively easily (I would like to avoid using the command line for everything regarding it, like in git shell). Is there something else I should be aware of (please, on this don't point me to other questions ... they just give me a ton of info, and I'm not sure what is it that I should take as important, and what to disregard). I'm trying to cut some time, since I cannot spend all that time relearning hg, like I did for git. I've also heard git is c project, while mercurial is python ... is there any noticeable difference in speed. git was pretty speedy ... will I encounter some waiting while working. Notice: All my projects are of let's say, middle size ... mostly numerical simulations ... 10-15000 lines (medium size?)

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• mysql index optimization for a table with multiple indexes that index some of the same columns

  - by Sean

  I have a table that stores some basic data about visitor sessions on third party web sites. This is its structure: id, site_id, unixtime, unixtime_last, ip_address, uid There are four indexes: id, site_id/unixtime, site_id/ip_address, and site_id/uid There are many different types of ways that we query this table, and all of them are specific to the site_id. The index with unixtime is used to display the list of visitors for a given date or time range. The other two are used to find all visits from an IP address or a "uid" (a unique cookie value created for each visitor), as well as determining if this is a new visitor or a returning visitor. Obviously storing site_id inside 3 indexes is inefficient for both write speed and storage, but I see no way around it, since I need to be able to quickly query this data for a given specific site_id. Any ideas on making this more efficient? I don't really understand B-trees besides some very basic stuff, but it's more efficient to have the left-most column of an index be the one with the least variance - correct? Because I considered having the site_id being the second column of the index for both ip_address and uid but I think that would make the index less efficient since the IP and UID are going to vary more than the site ID will, because we only have about 8000 unique sites per database server, but millions of unique visitors across all ~8000 sites on a daily basis. I've also considered removing site_id from the IP and UID indexes completely, since the chances of the same visitor going to multiple sites that share the same database server are quite small, but in cases where this does happen, I fear it could be quite slow to determine if this is a new visitor to this site_id or not. The query would be something like: select id from sessions where uid = 'value' and site_id = 123 limit 1 ... so if this visitor had visited this site before, it would only need to find one row with this site_id before it stopped. This wouldn't be super fast necessarily, but acceptably fast. But say we have a site that gets 500,000 visitors a day, and a particular visitor loves this site and goes there 10 times a day. Now they happen to hit another site on the same database server for the first time. The above query could take quite a long time to search through all of the potentially thousands of rows for this UID, scattered all over the disk, since it wouldn't be finding one for this site ID. Any insight on making this as efficient as possible would be appreciated :) Update - this is a MyISAM table with MySQL 5.0. My concerns are both with performance as well as storage space. This table is both read and write heavy. If I had to choose between performance and storage, my biggest concern is performance - but both are important. We use memcached heavily in all areas of our service, but that's not an excuse to not care about the database design. I want the database to be as efficient as possible.

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• C# Finalize/Dispose pattern

  - by robUK

  Hello, C# 2008 I have been working on this for a while now. And I am still confused about some issues. My questions below 1) I know that you only need a finalizer if you are disposing of unmanaged resources. However, if you are using managed resources that make calls to unmanaged resources. Would you still need to implement a finalizer? 2) However, if you develop a class that doesn't use any unmanged resources directly or indirectly and you implement the IDisposable so that clients of your class can use the 'using statement'. Would it be acceptable to implement the IDisposable just so that clients of your class can use the using statement? using(myClass objClass = new myClass()) { // Do stuff here } 3) I have developed this simple code below to demostrate the Finalize/dispose pattern: public class NoGateway : IDisposable { private WebClient wc = null; public NoGateway() { wc = new WebClient(); wc.DownloadStringCompleted += wc_DownloadStringCompleted; } // Start the Async call to find if NoGateway is true or false public void NoGatewayStatus() { // Start the Async's download // Do other work here wc.DownloadStringAsync(new Uri(www.xxxx.xxx)); } private void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e) { // Do work here } // Dispose of the NoGateway object public void Dispose() { wc.DownloadStringCompleted -= wc_DownloadStringCompleted; wc.Dispose(); GC.SuppressFinalize(this); } } Question about the source code: 1) Here I have not added the finalizer. And normally the finalizer will be called by the GC, and the finalizer will call the Dispose. As I don't have the finalizer, when do I call the Dispose method? Is it the client of the class that has to call it? So my class in the example is called NoGateway and the client could use and dispose of the class like this: Would the Dispose method be automatically called when execution reaches the end of the using block? using(NoGateway objNoGateway = new NoGateway()) { // Do stuff here } Or does the client have to manually call the dispose method i.e.? NoGateway objNoGateway = new NoGateway(); // Do stuff with object objNoGateway.Dispose(); // finished with it Many thanks for helping with all these questions, 2) I am using the webclient class in my 'NoGateway' class. Because the webclient implements the IDisposable interface. Does this mean that the webclient indirectly uses unmanaged resources? Is there any hard and fast rule to follow about this. How do I know that a class uses unmanaged resources?

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• Data aggregation mongodb vs mysql

  - by Dimitris Stefanidis

  I am currently researching on a backend to use for a project with demanding data aggregation requirements. The main project requirements are the following. Store millions of records for each user. Users might have more than 1 million entries per year so even with 100 users we are talking about 100 million entries per year. Data aggregation on those entries must be performed on the fly. The users need to be able to filter on the entries by a ton of available filters and then present summaries (totals , averages e.t.c) and graphs on the results. Obviously I cannot precalculate any of the aggregation results because the filter combinations (and thus the result sets) are huge. Users are going to have access on their own data only but it would be nice if anonymous stats could be calculated for all the data. The data is going to be most of the time in batch. e.g the user will upload the data every day and it could like 3000 records. In some later version there could be automated programs that upload every few minutes in smaller batches of 100 items for example. I made a simple test of creating a table with 1 million rows and performing a simple sum of 1 column both in mongodb and in mysql and the performance difference was huge. I do not remember the exact numbers but it was something like mysql = 200ms , mongodb = 20 sec. I have also made the test with couchdb and had much worse results. What seems promising speed wise is cassandra which I was very enthusiastic about when I first discovered it. However the documentation is scarce and I haven't found any solid examples on how to perform sums and other aggregate functions on the data. Is that possible ? As it seems from my test (Maybe I have done something wrong) with the current performance its impossible to use mongodb for such a project although the automated sharding functionality seems like a perfect fit for it. Does anybody have experience with data aggregation in mongodb or have any insights that might be of help for the implementation of the project ? Thanks, Dimitris

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• POD global object initialization

  - by paercebal

  I've got bitten today by a bug. The following source can be copy/pasted (and then compiled) into a main.cpp file #include <iostream> // The point of SomeGlobalObject is for its // constructor to be launched before the main // ... struct SomeGlobalObject { SomeGlobalObject() ; } ; // ... // Which explains the global object SomeGlobalObject oSomeGlobalObject ; // A POD... I was hoping it would be constructed at // compile time when using an argument list struct MyPod { short m_short ; const char * const m_string ; } ; // declaration/Initialization of a MyPod array MyPod myArrayOfPod[] = { { 1, "Hello" }, { 2, "World" }, { 3, " !" } } ; // declaration/Initialization of an array of array of void * void * myArrayOfVoid[][2] = { { (void *)1, "Hello" }, { (void *)2, "World" }, { (void *)3, " !" } } ; // constructor of the global object... Launched BEFORE main SomeGlobalObject::SomeGlobalObject() { std::cout << "myArrayOfPod[0].m_short : " << myArrayOfPod[0].m_short << std::endl ; std::cout << "myArrayOfVoid[0][0] : " << myArrayOfVoid[0][0] << std::endl ; } // main... What else ? int main(int argc, char* argv[]) { return 0 ; } MyPod being a POD, I believed there would be no constructors. Only initialization at compile time. Thus, the global object SomeGlobalObject would have no problem to use the global array of PODs upon its construction. The problem is that in real life, nothing is so simple. On Visual C++ 2008 (I did not test on other compilers), upon execution myArrayOfPodis not initialized, even ifmyArrayOfVoid` is initialized. So my questions is: Are C++ compilers not supposed to initialize global PODs (including POD structures) at compilation time ? Note that I know global variable are evil, and I know that one can't be sure of the order of creation of global variables declared in different compilation units. The problem here is really the POD C-like initialization which seems to call a constructor (the default, compiler-generated one?). And to make everyone happy: This is on debug. On release, the global array of PODs is correctly initialized.

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• pathinfo vs fnmatch

  - by zaf

  There was a small debate regarding the speed of fnmatch over pathinfo here : http://stackoverflow.com/questions/2692536/how-to-check-if-file-is-php I wasn't totally convinced so decided to benchmark the two functions. Using dynamic and static paths showed that pathinfo was faster. Is my benchmarking logic and conclusion valid? I include a sample of the results which are in seconds for 100,000 iterations on my machine : dynamic path pathinfo 3.79311800003 fnmatch 5.10071492195 x1.34 static path pathinfo 1.03921294212 fnmatch 2.37709188461 x2.29 Code: <pre> <?php $iterations=100000; // Benchmark with dynamic file path print("dynamic path\n"); $i=$iterations; $t1=microtime(true); while($i-->0){ $f='/'.uniqid().'/'.uniqid().'/'.uniqid().'/'.uniqid().'.php'; if(pathinfo($f,PATHINFO_EXTENSION)=='php') $d=uniqid(); } $t2=microtime(true) - $t1; print("pathinfo $t2\n"); $i=$iterations; $t1=microtime(true); while($i-->0){ $f='/'.uniqid().'/'.uniqid().'/'.uniqid().'/'.uniqid().'.php'; if(fnmatch('*.php',$f)) $d=uniqid(); } $t3 = microtime(true) - $t1; print("fnmatch $t3\n"); print('x'.round($t3/$t2,2)."\n\n"); // Benchmark with static file path print("static path\n"); $f='/'.uniqid().'/'.uniqid().'/'.uniqid().'/'.uniqid().'.php'; $i=$iterations; $t1=microtime(true); while($i-->0) if(pathinfo($f,PATHINFO_EXTENSION)=='php') $d=uniqid(); $t2=microtime(true) - $t1; print("pathinfo $t2\n"); $i=$iterations; $t1=microtime(true); while($i-->0) if(fnmatch('*.php',$f)) $d=uniqid(); $t3=microtime(true) - $t1; print("fnmatch $t3\n"); print('x'.round($t3/$t2,2)."\n\n"); ?> </pre>

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• Is my understanding of "select distinct" correct?

  - by paxdiablo

  We recently discovered a performance problem with one of our systems and I think I have the fix but I'm not certain my understanding is correct. In simplest form, we have a table blah into which we accumulate various values based on a key field. The basic form is: recdate date rectime time system varchar(20) count integer accum1 integer accum2 integer There are a lot more accumulators than that but they're all of the same form. The primary key is made up of recdate, rectime and system. As values are collected to the table, the count for a given recdate/rectime/system is incremented and the values for that key are added to the accumulators. That means the averages can be obtained by using accumN / count. Now we also have a view over that table specified as follows: create view blah_v ( recdate, rectime, system, count, accum1, accum2 ) as select distinct recdate, rectime, system, count, value (case when count > 0 then accum1 / count end, 0), value (case when count > 0 then accum2 / count end, 0) from blah; In other words, the view gives us the average value of the accumulators rather than the sums. It also makes sure we don't get a divide-by-zero in those cases where the count is zero (these records do exist and we are not allowed to remove them so don't bother telling me they're rubbish - you're preaching to the choir). We've noticed that the time difference between doing: select distinct recdate from XX varies greatly depending on whether we use the table or the view. I'm talking about the difference being 1 second for the table and 27 seconds for the view (with 100K rows). We actually tracked it back to the select distinct. What seems to be happening is that the DBMS is actually loading all the rows in and sorting them so as to remove duplicates. That's fair enough, it's what we stupidly told it to do. But I'm pretty sure the fact that the view includes every component of the primary key means that it's impossible to have duplicates anyway. We've validated the problem since, if we create another view without the distinct, it performs at the same speed as the underlying table. I just wanted to confirm my understanding that a select distinct can not have duplicates if it includes all the primary key components. If that's so, then we can simply change the view appropriately.

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• Spring AOP pointcut that matches annotation on interface

  - by seanizer

  Hello, this is my first post here, so I apologize in advance for any stupidity on my side. I have a service class implemented in Java 6 / Spring 3 that needs an annotation to restrict access by role. I have defined an annotation called RequiredPermission that has as its value attribute one or more values from an enum called OperationType: public @interface RequiredPermission { /** * One or more {@link OperationType}s that map to the permissions required * to execute this method. * * @return */ OperationType[] value();} public enum OperationType { TYPE1, TYPE2; } package com.mycompany.myservice; public interface MyService{ @RequiredPermission(OperationType.TYPE1) void myMethod( MyParameterObject obj ); } package com.mycompany.myserviceimpl; public class MyServiceImpl implements MyService{ public myMethod( MyParameterObject obj ){ // do stuff here } } I also have the following aspect definition: /** * Security advice around methods that are annotated with * {@link RequiredPermission}. * * @param pjp * @param param * @param requiredPermission * @return * @throws Throwable */ @Around(value = "execution(public *" + " com.mycompany.myserviceimpl.*(..))" + " && args(param)" + // parameter object " && @annotation( requiredPermission )" // permission annotation , argNames = "param,requiredPermission") public Object processRequest(final ProceedingJoinPoint pjp, final MyParameterObject param, final RequiredPermission requiredPermission) throws Throwable { if(userService.userHasRoles(param.getUsername(),requiredPermission.values()){ return pjp.proceed(); }else{ throw new SorryButYouAreNotAllowedToDoThatException( param.getUsername(),requiredPermission.value()); } } The parameter object contains a user name and I want to look up the required role for the user before allowing access to the method. When I put the annotation on the method in MyServiceImpl, everything works just fine, the pointcut is matched and the aspect kicks in. However, I believe the annotation is part of the service contract and should be published with the interface in a separate API package. And obviously, I would not like to put the annotation on both service definition and implementation (DRY). I know there are cases in Spring AOP where aspects are triggered by annotations one interface methods (e.g. Transactional). Is there a special syntax here or is it just plain impossible out of the box. PS: I have not posted my spring config, as it seems to be working just fine. And no, those are neither my original class nor method names. Thanks in advance, Sean PPS: Actually, here is the relevant part of my spring config: <aop:aspectj-autoproxy proxy-target-class="false" /> <bean class="com.mycompany.aspect.MyAspect"> <property name="userService" ref="userService" /> </bean>

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• Maven mercurial extension constantly fails

  - by TheLQ

  After 2+ hours I was able to get the maven-scm-provider-hg extension (for pushing to mercurial repos from Maven) semi working, meaning that it was executing commands instead of just giving errors. However I think I've run into a wall with this error [INFO] [deploy:deploy {execution: default-deploy}] [INFO] Retrieving previous build number from pircbotx.googlecode.com [INFO] Removing C:\DOCUME~1\Owner\LOCALS~1\Temp\wagon-scm1210107000.checkout\pir cbotx\pircbotx\1.3-SNAPSHOT [INFO] EXECUTING: cmd.exe /X /C "hg clone -r tip https://*SNIP*@site.pircbotx.googlecode.com/hg/maven2/snapshots/pircbotx/pircbotx/1.3-SNAPSHOT C:\DOCUME~1\Owner\LOCALS~1\Temp\wagon-scm1210107000.checkout\pircbotx\pircbotx\1.3-SNAPSHOT" [INFO] EXECUTING: cmd.exe /X /C "hg locate" [INFO] repository metadata for: 'snapshot pircbotx:pircbotx:1.3-SNAPSHOT' could not be found on repository: pircbotx.googlecode.com, so will be created Uploading: scm:hg:https://site.pircbotx.googlecode.com/hg/maven2/snapshots/pircbotx/pircbotx/1.3-SNAPSHOT/pircbotx-1.3-SNAPSHOT.jar [INFO] ------------------------------------------------------------------------ [ERROR] BUILD ERROR [INFO] ------------------------------------------------------------------------ [INFO] Error deploying artifact: Error listing repository: No such command 'list'. What on earth would cause that error? I'm on a Windows box, so any commands that aren't commands give "'list' is not recognized as an internal or external command...", not "No such command 'list'." POM <build> <extensions> <extension> <groupId>org.apache.maven.scm</groupId> <artifactId>maven-scm-provider-hg</artifactId> <version>1.4</version> </extension> <extension> <groupId>org.apache.maven.wagon</groupId> <artifactId>wagon-scm</artifactId> <version>1.0-beta-7</version> </extension> </extensions> ... <distributionManagement> <snapshotRepository> <id>pircbotx.googlecode.com</id> <name>PircBotX Site</name> <url>scm:hg:https://site.pircbotx.googlecode.com/hg/maven2/snapshots</url> <uniqueVersion>false</uniqueVersion> </snapshotRepository> </distributionManagement> Mercurial version W:\programming\pircbot-hg>hg version Mercurial Distributed SCM (version 1.7.2) Any suggestions?

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• PERL newbie : get a proper minimal debug_mode solution

  - by Michael Mao

  Hi all: I am learning PERL in a "head-first" manner. I am absolutely a newbie in this language: I am trying to have a debug_mode switch from CLI which can be used to control how my script works, by switching certain subroutines "on and off". And below is what I've got so far: #!/usr/bin/perl -s -w # purpose : make subroutine execution optional, # which is depending on a CLI switch flag use strict; use warnings; use constant DEBUG_VERBOSE => "v"; use constant DEBUG_SUPPRESS_ERROR_MSGS => "s"; use constant DEBUG_IGNORE_VALIDATION => "i"; use constant DEBUG_SETPPING_COMPUTATION => "c"; our ($debug_mode); mainMethod(); sub mainMethod # () { if(!$debug_mode) { print "debug_mode is OFF\n"; } elsif($debug_mode) { print "debug_mode is ON\n"; } else { print "OMG!\n"; exit -1; } checkArgv(); printErrorMsg("Error_Code_123", "Parsing Error at..."); verbose(); } sub checkArgv #() { print ("Number of ARGV : ".(1 + $#ARGV)."\n"); } sub printErrorMsg # ($error_code, $error_msg, ..) { if(defined($debug_mode) && !($debug_mode =~ DEBUG_SUPPRESS_ERROR_MSGS)) { print "You can only see me if -debug_mode is NOT set". " to DEBUG_SUPPRESS_ERROR_MSGS\n"; die("terminated prematurely...\n") and exit -1; } } sub verbose # () { if(defined($debug_mode) && ($debug_mode =~ DEBUG_VERBOSE)) { print "Blah blah blah...\n"; } } So far as I can tell, at least it works...: the -debug_mode switch doesn't interfere with normal ARGV the following commandlines work: ./optional.pl ./optional.pl -debug_mode ./optional.pl -debug_mode=v ./optional.pl -debug_mode=s However, I am puzzled when multiple debug_modes are "mixed", such as: ./optional.pl -debug_mode=sv ./optional.pl -debug_mode=vs I don't understand why the above lines of code "magically works". I see both of the "DEBUG_VERBOS" and "DEBUG_SUPPRESS_ERROR_MSGS" apply to the script, which is fine in this case. However, if there are some "conflicting" debug modes, I am not sure how to set the "precedence of debue_modes"? Also, I am not certain if my approach is good enough to Perlists and I hope I am getting my feet in the right direction. One biggest problem is that I now put if statements inside most of my subroutines for controlling their behavior under different modes. Is this okay? Is there a more elegant way? I know there must be a debug module from CPAN or elsewhere, but I wanna a real minimal solution that doesn't depend on any other module than the "default" And I cannot have any control on the environment where this script will be executed... Many thanks to the suggestions in advance.

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