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  • DuplicateKeyException in LINQ, but I've set auto increment and auto sync

    - by Fritos
    I'm getting a DuplicateKeyException error in my C# code. I've set Auto Generated = true, and Auto-Sync = OnInsert in my dbml. I'm not even touching the PK field in any manually written code (as seen below [My primary key field is actually called PK]). using (DeviceExerciseDataDataContext context = new DeviceExerciseDataDataContext()) { foreach(Data tgudData in data.Data) { tgd = new tableData(); tgd.FK = key; tgd.Time = tgudData.TimeStamp; tgd.Calories = Convert.ToInt32(tgudData.Calories); tgd.HeartRate = tgudData.AvgHr; tgd.BenchAngle = tgudData.Angle; tgd.WorkoutTarget = 0; tgd.Reps = tgudData.Reps; context.tableDatas.InsertOnSubmit(tgd); } context.SubmitChanges(); } This is the code for the column in the designer (columns are named PK and FK) [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_PK", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL", IsPrimaryKey=true, IsDbGenerated=true)] public int PK { get { return this._PK; } set { if ((this._PK != value)) { this.OnPKChanging(value); this.SendPropertyChanging(); this._PK = value; this.SendPropertyChanged("PK"); this.OnPKChanged(); } } } [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_FK", DbType="Int")] public System.Nullable<int> FK { get { return this._FK; } set { if ((this._FK != value)) { this.OnFKChanging(value); this.SendPropertyChanging(); this._FK = value; this.SendPropertyChanged("FK"); this.OnFKChanged(); } } }

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  • Multi-Column Join in Hibernate/JPA Annotations

    - by bowsie
    I have two entities which I would like to join through multiple columns. These columns are shared by an @Embeddable object that is shared by both entities. In the example below, Foo can have only one Bar but Bar can have multiple Foos (where AnEmbeddableObject is a unique key for Bar). Here is an example: @Entity @Table(name = "foo") public class Foo { @Id @Column(name = "id") @GeneratedValue(generator = "seqGen") @SequenceGenerator(name = "seqGen", sequenceName = "FOO_ID_SEQ", allocationSize = 1) private Long id; @Embedded private AnEmbeddableObject anEmbeddableObject; @ManyToOne(targetEntity = Bar.class, fetch = FetchType.LAZY) @JoinColumns( { @JoinColumn(name = "column_1", referencedColumnName = "column_1"), @JoinColumn(name = "column_2", referencedColumnName = "column_2"), @JoinColumn(name = "column_3", referencedColumnName = "column_3"), @JoinColumn(name = "column_4", referencedColumnName = "column_4") }) private Bar bar; // ... rest of class } And the Bar class: @Entity @Table(name = "bar") public class Bar { @Id @Column(name = "id") @GeneratedValue(generator = "seqGen") @SequenceGenerator(name = "seqGen", sequenceName = "BAR_ID_SEQ", allocationSize = 1) private Long id; @Embedded private AnEmbeddableObject anEmbeddableObject; // ... rest of class } Finally the AnEmbeddedObject class: @Embeddable public class AnEmbeddedObject { @Column(name = "column_1") private Long column1; @Column(name = "column_2") private Long column2; @Column(name = "column_3") private Long column3; @Column(name = "column_4") private Long column4; // ... rest of class } Obviously the schema is poorly normalised, it is a restriction that AnEmbeddedObject's fields are repeated in each table. The problem I have is that I receive this error when I try to start up Hibernate: org.hibernate.AnnotationException: referencedColumnNames(column_1, column_2, column_3, column_4) of Foo.bar referencing Bar not mapped to a single property I have tried marking the JoinColumns are not insertable and updatable, but with no luck. Is there a way to express this with Hibernate/JPA annotations? Thank you.

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  • Producer consumer with qualifications

    - by tgguy
    I am new to clojure and am trying to understand how to properly use its concurrency features, so any critique/suggestions is appreciated. So I am trying to write a small test program in clojure that works as follows: there 5 producers and 2 consumers a producer waits for a random time and then pushes a number onto a shared queue. a consumer should pull a number off the queue as soon as the queue is nonempty and then sleep for a short time to simulate doing work the consumers should block when the queue is empty producers should block when the queue has more than 4 items in it to prevent it from growing huge Here is my plan for each step above: the producers and consumers will be agents that don't really care for their state (just nil values or something); i just use the agents to send-off a "consumer" or "producer" function to do at some time. Then the shared queue will be (def queue (ref [])). Perhaps this should be an atom though? in the "producer" agent function, simply (Thread/sleep (rand-int 1000)) and then (dosync (alter queue conj (rand-int 100))) to push onto the queue. I am thinking to make the consumer agents watch the queue for changes with add-watcher. Not sure about this though..it will wake up the consumers on any change, even if the change came from a consumer pulling something off (possibly making it empty) . Perhaps checking for this in the watcher function is sufficient. Another problem I see is that if all consumers are busy, then what happens when a producer adds something new to the queue? Does the watched event get queued up on some consumer agent or does it disappear? see above I really don't know how to do this. I heard that clojure's seque may be useful, but I couldn't find enough doc on how to use it and my initial testing didn't seem to work (sorry don't have the code on me anymore)

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  • How good is the memory mapped Circular Buffer on Wikipedia?

    - by abroun
    I'm trying to implement a circular buffer in C, and have come across this example on Wikipedia. It looks as if it would provide a really nice interface for anyone reading from the buffer, as reads which wrap around from the end to the beginning of the buffer are handled automatically. So all reads are contiguous. However, I'm a bit unsure about using it straight away as I don't really have much experience with memory mapping or virtual memory and I'm not sure that I fully understand what it's doing. What I think I understand is that it's mapping a shared memory file the size of the buffer into memory twice. Then, whenever data is written into the buffer it appears in memory in 2 places at once. This allows all reads to be contiguous. What would be really great is if someone with more experience of POSIX memory mapping could have a quick look at the code and tell me if the underlying mechanism used is really that efficient. Am I right in thinking for example that the file in /dev/shm used for the shared memory always stays in RAM or could it get written to the hard drive (performance hit) at some point? Are there any gotchas I should be aware of? As it stands, I'm probably going to use a simpler method for my current project, but it'd be good to understand this to have it in my toolbox for the future. Thanks in advance for your time.

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  • Kohana Sessions data does not persist across pages in chrome and ir browsers

    - by user1062637
    Kohana Session data does not persist across pages opened in Chrome and IE browsers the same works fine in a Firefox browser Kohana version used is 2.3 session config files hold $config['driver'] = 'native'; /** * Session storage parameter, used by drivers. */ $config['storage'] = ''; /** * Session name. * It must contain only alphanumeric characters and underscores. At least one letter must be present. */ $config['name'] = 'NITWSESSID'; /** * Session parameters to validate: user_agent, ip_address, expiration. */ $config['validate'] = array(); /** * Enable or disable session encryption. * Note: this has no effect on the native session driver. * Note: the cookie driver always encrypts session data. Set to TRUE for stronger encryption. */ $config['encryption'] = FALSE; /** * Session lifetime. Number of seconds that each session will last. * A value of 0 will keep the session active until the browser is closed (with a limit of 24h). */ $config['expiration'] = 2700; /** * Number of page loads before the session id is regenerated. * A value of 0 will disable automatic session id regeneration. */ $config['regenerate'] = 0; /** * Percentage probability that the gc (garbage collection) routine is started. */ $config['gc_probability'] = 2; Help needed urgently

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  • array of structures, or structure of arrays?

    - by Jason S
    Hmmm. I have a table which is an array of structures I need to store in Java. The naive don't-worry-about-memory approach says do this: public class Record { final private int field1; final private int field2; final private long field3; /* constructor & accessors here */ } List<Record> records = new ArrayList<Record>(); If I end up using a large number ( 106 ) of records, where individual records are accessed occasionally, one at a time, how would I figure out how the preceding approach (an ArrayList) would compare with an optimized approach for storage costs: public class OptimizedRecordStore { final private int[] field1; final private int[] field2; final private long[] field3; Record getRecord(int i) { return new Record(field1[i],field2[i],field3[i]); } /* constructor and other accessors & methods */ } edit: assume the # of records is something that is changed infrequently or never I'm probably not going to use the OptimizedRecordStore approach, but I want to understand the storage cost issue so I can make that decision with confidence. obviously if I add/change the # of records in the OptimizedRecordStore approach above, I either have to replace the whole object with a new one, or remove the "final" keyword. kd304 brings up a good point that was in the back of my mind. In other situations similar to this, I need column access on the records, e.g. if field1 and field2 are "time" and "position", and it's important for me to get those values as an array for use with MATLAB, so I can graph/analyze them efficiently.

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  • asp.net webpages content block and helper differences

    - by metanaito
    In asp.net webpages framework what is the difference between using a content block versus a helper? They both seem to be used to output HTML to multiple pages. They both can contain code and both can pass parameters. Are there other differences? When should you use a helper versus a content block? More info: With Content Blocks we create a .cshtml (for example _MakeNote.cshtml) file to hold the content we want to insert into a page. Then we use: @RenderPage("/Shared/_MakeNote.cshtml") to insert the content into a page. We can pass parameters to the content block like this: @RenderPage("/Shared/_MakeNote.cshtml", new { content = "hello from content block" }) It's somewhat like an include file, but I think does not share scope with the parent page. With Helpers we create a .cshtml page in the App_Code folder (for example MyHelpers.cshtml) and place methods in that page which we want to call. The method looks something like this: @helper MakeNote(string content) { <div>@content</div> } The helper is called by using: @MyHelpers.MakeNote("Hello from helper")

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  • mysql: storing arbitrary data

    - by Hailwood
    Background: I was asking a question on stack overflow regarding creating tables on the fly where this conversation ensued: This smells like a terrible idea! In fact, it smells just like this one. What in the world do you want to use this for? – deceze @deceze: very true, However, How else would you store the contents of these CSV files. They must be stored in mysql for indexing. The only solid fact about them is that they all have a mobile column with a standard format. The CSV can have an arbitrary amount of columns with an arbitrary amount of rows. They can (with no exaggeration) range from a single row, 35 column csv to an 80k row single column CSV. I am open to other ideas. – Hailwood There are many solutions for this, from attribute-value schemas to JSON storage and NoSQL storage. Open a new question about it. Whatever you do though, don't dynamically create tables! – deceze Question: So my question is, What would you say is the best way to store this data? Are you in agreement with deceze about not creating dynamic tables?

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  • Qt application crashing immediately without debugging info. How do I track down the problem?

    - by jjacksonRIAB
    I run an Qt app I've built: ./App Segmentation fault I run it with strace: strace ./App execve("./App", ["./App"], [/* 27 vars */]) = 0 --- SIGSEGV (Segmentation fault) @ 0 (0) --- +++ killed by SIGSEGV +++ Process 868 detached Again, no useful info. I run it with gdb: (gdb) run Starting program: /root/test/App Reading symbols from shared object read from target memory...(no debugging symbols found)...done. Loaded system supplied DSO at 0xffffe000 Program received signal SIGSEGV, Segmentation fault. 0x00000001 in ?? () Again, nothing. I run it with valgrind: ==948== Process terminating with default action of signal 11 (SIGSEGV) ==948== Bad permissions for mapped region at address 0x0 ==948== at 0x1: (within /root/test/App) Even if I put in debugging symbols, it doesn't give any more useful info. ldd shows all libraries being linked properly. Is there any other way I can find out what's wrong? I can't even do standard printf, cout, etc debugging. The executable doesn't even seem to start running at all. I rebuilt with symbols, and tried the suggestion below (gdb) break main Breakpoint 1 at 0x45470 (gdb) run Starting program: /root/test/App Breakpoint 1 at 0x80045470 Reading symbols from shared object read from target memory...done. Loaded system supplied DSO at 0xffffe000 Program received signal SIGSEGV, Segmentation fault. 0x00000001 in ?? () I checked for static initializers and I don't seem to have any. Yep, I tried printf, cout, etc. It doesn't even make it into the main routine, so I'm looking for problems with static initializers in link libraries, adding them in one-by-one. I'm not getting any stack traces either.

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  • Will this class cause memory leaks, and does it need a dispose method? (asp.net vb)

    - by Phil
    Here is the class to export a gridview to an excel sheet: Imports System Imports System.Data Imports System.Configuration Imports System.IO Imports System.Web Imports System.Web.Security Imports System.Web.UI Imports System.Web.UI.WebControls Imports System.Web.UI.WebControls.WebParts Imports System.Web.UI.HtmlControls Namespace ExcelExport Public NotInheritable Class GVExportUtil Private Sub New() End Sub Public Shared Sub Export(ByVal fileName As String, ByVal gv As GridView) HttpContext.Current.Response.Clear() HttpContext.Current.Response.AddHeader("content-disposition", String.Format("attachment; filename={0}", fileName)) HttpContext.Current.Response.ContentType = "application/ms-excel" Dim sw As StringWriter = New StringWriter Dim htw As HtmlTextWriter = New HtmlTextWriter(sw) Dim table As Table = New Table table.GridLines = GridLines.Vertical If (Not (gv.HeaderRow) Is Nothing) Then GVExportUtil.PrepareControlForExport(gv.HeaderRow) table.Rows.Add(gv.HeaderRow) End If For Each row As GridViewRow In gv.Rows GVExportUtil.PrepareControlForExport(row) table.Rows.Add(row) Next If (Not (gv.FooterRow) Is Nothing) Then GVExportUtil.PrepareControlForExport(gv.FooterRow) table.Rows.Add(gv.FooterRow) End If table.RenderControl(htw) HttpContext.Current.Response.Write(sw.ToString) HttpContext.Current.Response.End() End Sub Private Shared Sub PrepareControlForExport(ByVal control As Control) Dim i As Integer = 0 Do While (i < control.Controls.Count) Dim current As Control = control.Controls(i) If (TypeOf current Is LinkButton) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, LinkButton).Text)) ElseIf (TypeOf current Is ImageButton) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, ImageButton).AlternateText)) ElseIf (TypeOf current Is HyperLink) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, HyperLink).Text)) ElseIf (TypeOf current Is DropDownList) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, DropDownList).SelectedItem.Text)) ElseIf (TypeOf current Is CheckBox) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, CheckBox).Checked)) End If If current.HasControls Then GVExportUtil.PrepareControlForExport(current) End If i = (i + 1) Loop End Sub End Class End Namespace Will this class cause memory leaks? And does anything here need to be disposed of? The code is working but I am getting frequent crashes of the app pool when it is in use. Thanks.

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  • How to check whether user is login in web application?

    - by Morgan Cheng
    I want to learn the whole details of web application authentication. So, I decided to write a CodeIgniter authentication library from scratch. Now, I have to make design decision about how to determine whether one user is login. Basically, after user input username & password pair. A cookie is set for this session, following navigations in the web application will not require username & password. The server side will check whether the session cookie is valid to determine whether current user is login. The question is: how to determine whether cookie is valid cookie issued from server side? I can image the most simple way is to have the cookie value stored in session status as well. For each HTTP request, compare the value from cookie and the value from server session. (Since CodeIgniter session library store session variables in cookies, it is not applicable without some tweak.) This method requires storage in server side. For huge web application that is deployed in multiple datacenters. It is possible that user input username & password when browsing in one datacenter, while he/she access the web application in another datacenter later. The expected behavior is that user just input username & password once. As a result, all datacenters should be able to access the session status. That is possible not applicable even the session status is stored in external storage such as database. I tried Google. I login Google with Asian proxy which is supposed to direct me to datacenters in Asian. Then I switch to North American proxy which should direct me to datacenters in North America. It recognize my login without asking username and password again. So, is there any way to determine whether user is login without server side session status?

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  • What about race condition in multithreaded reading?

    - by themoob
    Hi, According to an article on IBM.com, "a race condition is a situation in which two or more threads or processes are reading or writing some shared data, and the final result depends on the timing of how the threads are scheduled. Race conditions can lead to unpredictable results and subtle program bugs." . Although the article concerns Java, I have in general been taught the same definition. As far as I know, simple operation of reading from RAM is composed of setting the states of specific input lines (address, read etc.) and reading the states of output lines. This is an operation that obviously cannot be executed simultaneously by two devices and has to be serialized. Now let's suppose we have a situation when a couple of threads access an object in memory. In theory, this access should be serialized in order to prevent race conditions. But e.g. the readers/writers algorithm assumes that an arbitrary number of readers can use the shared memory at the same time. So, the question is: does one have to implement an exclusive lock for read when using multithreading (in WinAPI e.g.)? If not, why? Where is this control implemented - OS, hardware? Best regards, Kuba

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  • WiX major upgrade! Need different behaviors for different components...

    - by Joshua
    Okay! I have finally more closely identified the problem I'm having. In my installer, I was attempting to get a settings file to REMAIN INTACT on a major upgrade. I finally got this to work with the suggestion to set <InstallExecuteSequence> <RemoveExistingProducts After="InstallFinalize" /> </InstallExecuteSequence> This is successful in forcing this component to leave the original, not replacing it if it exists: <Component Id="Settings" Guid="A3513208-4F12-4496-B609-197812B4A953" NeverOverwrite="yes"> <File Id="settingsXml" KeyPath="yes" ShortName="SETTINGS.XML" Name="Settings.xml" DiskId="1" Source="\\fileserver\Release\Pathways\Dependencies\Settings\settings.xml" Vital="yes" /> </Component> HOWEVER! This is a problem! I have another component listed here: <Component Id="Database" Guid="1D8756EF-FD6C-49BC-8400-299492E8C65D" KeyPath="yes"> <File Id="pathwaysMdf" Name="Pathways.mdf" DiskId="1" Source="\\fileserver\Shared\Databases\Pathways\SystemDBs\Pathways.mdf" Vital="yes"/> <File Id="pathwaysLdf" Name="Pathways_log.ldf" DiskId="1" Source="\\fileserver\Shared\Databases\Pathways\SystemDBs\Pathways.ldf" Vital="yes"/> </Component> And this component MUST BE REPLACED on a major upgrade. I can only accomplish this so far by setting <RemoveExistingProducts After="InstallInitialize" /> THIS BREAKS THE FIRST FUNCTIONALITY I NEED WITH THE SETTINGS FILE. HOW CAN I DO BOTH?!

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  • how to make a software and preserve database integrity and correctness and please help confused

    - by user287745
    i have made an application project in vs 08 c#, sql server from vs 08. the database has like 20 tables and many fields in each have made an interface for adding deleting editting and retrieving data according to predefined needs of the users. now i have to 1) make to project in to a software which i can deliver to professor. that is he can just double click the icon and the software simply starts. no vs 08 needed to start the debugging 2) the database will be on one powerful computer (dual core latest everything win xp) and the user will access it from another computer connected using LAN i am able to change the connection string to the shared database using vs 08/ debugger whenever the server changes but how am i supposed to do that when its a software? 3)there will by many clients am i supposed to give the same software to every one, so they all can connect to the database, how will the integrity and correctness of the database be maintained? i mean the db.mdf file will be in a folder which will be shared with read and write access. so its not necessary that only one user will write at a time. so is there any coding for this or? please help me out here i am stuck do not know what to do i have no practical experience, would appreciate all the help thank you

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  • SqlServer slow on production environment

    - by Lieven Cardoen
    I have a weird problem in a production environment at a customer. I can't give any details on the infrastructure except that sql server runs on a virtual server and the data, log and filestream file are on another storage server (data and filestream together and log on a seperate server). Now, there's this query that when we run it gives these durations (first we clear the cache): 300ms, 20ms, 15ms, 17ms,... First time it takes longer, but from then on it is cached. At the customer, on a sql server that is more powerfull, these are the durations (I didn't have the rights to clear the cache. Will try this tomorrow). 2500ms, 2600ms, 2400ms, ... The query can be improved, that's right, but that's not the question here. How would you tackle this? I don't know where to go from here. The servers at this customer are really more powerfull but they do have virtual servers (we don't). What could be the cause... - Not enough memory? - Fragmentation? - Physical storage? I know it can be a lot of things, but maybe some of you have got some info for me on how to go on with this issue...

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  • Will this class cause memory leaks, and does anything need disposing of? (asp.net vb)

    - by Phil
    Here is the class to export a gridview to an excel sheet: Imports System Imports System.Data Imports System.Configuration Imports System.IO Imports System.Web Imports System.Web.Security Imports System.Web.UI Imports System.Web.UI.WebControls Imports System.Web.UI.WebControls.WebParts Imports System.Web.UI.HtmlControls Namespace ExcelExport Public NotInheritable Class GVExportUtil Private Sub New() End Sub Public Shared Sub Export(ByVal fileName As String, ByVal gv As GridView) HttpContext.Current.Response.Clear() HttpContext.Current.Response.AddHeader("content-disposition", String.Format("attachment; filename={0}", fileName)) HttpContext.Current.Response.ContentType = "application/ms-excel" Dim sw As StringWriter = New StringWriter Dim htw As HtmlTextWriter = New HtmlTextWriter(sw) Dim table As Table = New Table table.GridLines = GridLines.Vertical If (Not (gv.HeaderRow) Is Nothing) Then GVExportUtil.PrepareControlForExport(gv.HeaderRow) table.Rows.Add(gv.HeaderRow) End If For Each row As GridViewRow In gv.Rows GVExportUtil.PrepareControlForExport(row) table.Rows.Add(row) Next If (Not (gv.FooterRow) Is Nothing) Then GVExportUtil.PrepareControlForExport(gv.FooterRow) table.Rows.Add(gv.FooterRow) End If table.RenderControl(htw) HttpContext.Current.Response.Write(sw.ToString) HttpContext.Current.Response.End() End Sub Private Shared Sub PrepareControlForExport(ByVal control As Control) Dim i As Integer = 0 Do While (i < control.Controls.Count) Dim current As Control = control.Controls(i) If (TypeOf current Is LinkButton) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, LinkButton).Text)) ElseIf (TypeOf current Is ImageButton) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, ImageButton).AlternateText)) ElseIf (TypeOf current Is HyperLink) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, HyperLink).Text)) ElseIf (TypeOf current Is DropDownList) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, DropDownList).SelectedItem.Text)) ElseIf (TypeOf current Is CheckBox) Then control.Controls.Remove(current) control.Controls.AddAt(i, New LiteralControl(CType(current, CheckBox).Checked)) End If If current.HasControls Then GVExportUtil.PrepareControlForExport(current) End If i = (i + 1) Loop End Sub End Class End Namespace Will this class cause memory leaks? And does anything here need to be disposed of? The code is working but I am getting the app pool falling over frequently when it is in use. Thanks.

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  • Need some clarification on the ANSI/SPARC 3-tier database architecture.

    - by Moonshield
    Hi there, I'm currently revising for a databases exam and looking over some past papers, but there's one question that I'm slightly unsure about and was wondering if someone could offer some assistance. "Describe EACH of the THREE levels of the ANSI SPARC 3 level architecture. Your answer should include the purpose of EACH of the schemas, the level of abstraction they provide and the software tools that would be used to access and support them." As I understand it (although please correct me if I'm wrong): the internal schema specifies the physical storage of the data; the conceptual schema specifies the structure of the database and the domains; and the external schemas are how the database is viewed by "users" (applications, etc.). As for the abstraction, I understand that the conceptual layer means that the physical data storage can be altered without the end user being affected, likewise the The bit that I'm not sure about is what tools are used to access and support each layer. Would the internal schema be handled by the DBMS, the conceptual schema handled by some sort of DDL interpreter and the external schema handled by a DML interpreter (or have I misunderstood what each level does)? Any assistance would be greatly appreciated. Thanks, Moonshield

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  • Java ArrayList remove dupes without sets

    - by Kieran
    I'm having problems removing duplicates from an ArrayList. It's for an assignment for college. Here's the code I have already: public int numberOfDiffWords() { ArrayList<String> list = new ArrayList<>(); for(int i=0; i<words.size()-1; i++) { for(int j=i+1; j<words.size(); j++) { if(words.get(i).equals(words.get(j))) { // do nothing } else { list.add(words.get(i)); } } } return list.size(); } The problem is in the numberOfDiffWords() method. The populate list method is working correctly, as my instructor has given me a sample string (containing 4465 words) to analyse - printing words.size() gives the correct result. I want to return the size of the new ArrayList with all duplicates removed. words is an ArrayList class attribute. UPDATE: I should have mentioned I'm only allowed to use dynamic indexed-based storage for this part of the assignment, which means no hash-based storage.

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  • NoClassDefFoundError when trying to reference external jar files

    - by opike
    I have some 3rd party jar files that I want to reference in my tomcat web application. I added this line to catalina.properties: shared.loader=/home/ollie/dev/java/googleapi_samples/gdata/java/lib/*.jar but I'm still getting this error: org.apache.jasper.JasperException: javax.servlet.ServletException: java.lang.NoClassDefFoundError: com/google/gdata/util/ServiceException org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:491) org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:401) org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313) org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260) javax.servlet.http.HttpServlet.service(HttpServlet.java:717) I verified that the com.google.gdata.util.ServiceException is in the gdata-core-1.0.jar file which is in the directory: /home/ollie/dev/java/googleapi_samples/gdata/java/lib I did bounce tomcat after I modified catalina.properties. Update 1: I tried copying the gdata-core-1.0.jar file into /var/lib/tomcat6/webapp/examples/WEB-INF/lib as a test but that didn't fix the problem either. Update 2: It actually does work when I copy the jar file directly into the WEB-INF/lib directory. There was a permissions issue that I had to resolve. But it's still not working when I use the shared.loader setting. I reconfirmed that the path is correct.

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  • Transferring HashMap between client and server using Sockets (JAVA)

    - by sar
    I am working on a JAVA project in which there are multiple terminals. These terminals act as client and servers. For example if there are 3 terminals A,B and C.Then at any given point in time one of them say A, will be a client making broadcast request. The other two terminals, B and C, will reply. I am using sockets to make them communicate. Once the reply is received from all the other terminals A will check the pool of channels to see if any one of the channel is free. It takes up the free channel and making it availabilty false. The channelpool is implemented using HashMAp: HashMap channelpool = new HashMap(); channelpool = 1=true, 2=true, 3=false, 4=true, 5=true, 6=true, 7=true, 8=true, 9=true, 10=true So initially all the channels are true, any terminal can take any channel. But once the channel is taken it is set to false for the period of use and then reset to true. Now this Hashmap has to be shared among the distributed terminals. Also it should be kept up to date. I can not used a shared resource among the terminals to store the HashMap.Can someone tell me an easy way to transfer the HashMap between the terminals. I will appreciate if someone could point me to a website which discusses this.

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  • Calling into a saved java object via JNI from a different thread

    - by Drake Amara
    I have a java object which calls into a C++ shared object via JNI. In C++, I am saving a reference to the JNIEnv and jObject. JavaVM * jvm; JNIEnv * myEnv; jobject myobj; JNIEXPORT void JNICALL Java_org_api_init (JNIEnv *env, jobject jObj) { myEnv = env; myobj = jObj; } I also have a GLSurface renderer and it eventually calls the C++ shared object mentioned above on a different thread, the GLThread. I am then trying to call back into my original Java object using the jobject I saved initially, but I think because I am on the GLThread, I get the following error. W/dalvikvm(16101): JNI WARNING: 0x41ded218 is not a valid JNI reference I/dalvikvm(16101): "GLThread 981" prio=5 tid=15 RUNNABLE I/dalvikvm(16101): | group="main" sCount=0 dsCount=0 obj=0x41d6e220 self=0x5cb11078 I/dalvikvm(16101): | sysTid=16133 nice=0 sched=0/0 cgrp=apps handle=1555429136 I/dalvikvm(16101): | schedstat=( 0 0 0 ) utm=42 stm=32 core=1 The code calling back into Java : void setData() { jvm->AttachCurrentThread(&myEnv, 0); jclass javaClass = myEnv->FindClass("com/myapp/myClass"); if(javaClass == NULL){ LOGD("ERROR - cant find class"); } jmethodID method = myEnv->GetMethodID(javaClass, "updateDataModel", "()V"); if(method == NULL){ LOGD("ERROR - cant access method"); } // this works, but its a new java object //jobject myobj2 = myEnv->NewObject(javaClass, method); //this is where the crash occurs myEnv->CallVoidMethod(myobj, method, NULL); } If instead I create a new jObject using env-NewObject, I can succuessfully call back into Java, but it is a new object and I dont want that. I need to get back to my original Java Object. Is it a matter of switching threads before I call back into Java? If so, how do I do so ?

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  • How can I prevent double file uploading with Amazon S3?

    - by Tony
    I decided to use Amazon S3 for document storage for an app I am creating. One issue I run into is while I need to upload the files to S3, I need to create a document object in my app so my users can perform CRUD actions. One solution is to allow for a double upload. A user uploads a document to the server my Rails app lives on. I validate and create the object, then pass it on to S3. One issue with this is progress indicators become more complicated. Using most out-of-the-box plugins would show the client that file has finished uploading because it is on my server, but then there would be a decent delay when the file was going from my server to S3. This also introduces unnecessary bandwidth (at least it does not seem necessary) The other solution I am thinking about is to upload the file directly to S3 with one AJAX request, and when that is successful, make a second AJAX request to store the object in my database. One issue here is that I would have to validate the file after it is uploaded which means I have to run some clean up code in S3 if the validation fails. Both seem equally messy. Does anyone have something more elegant working that they would not mind sharing? I would imagine this is a common situation with "cloud storage" being quite popular today. Maybe I am looking at this wrong.

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  • Windows Phone 7, login screen redirect and a case for .exit?

    - by Jarrette
    I know this has been discussed ad nauseum, but I want to present my case.... 1. My start page in my app is login.xaml. The user logs in, the username and password are authenticated through my WCF service, the username is saved in isolated storage, and then the user is redirected to mainpage.xaml. When a user starts my app, and they already have a saved username in isolated storage, they are redirected to mainpage.xaml If the user hit's "back" hard button from mainpage.xaml, they are redirected to the login screen, which in turn redirects them back to the mainpage.xaml since they already have a saved local username. This is causing my app to fail certification currently since the user cannot hit the "back" button to exit the app from mainpage.xaml. My instinct here is to override the BackKeyPress in mainpage.xaml and exit the app somehow. By reading the other posts, I can see that this method is not available. My second idea was to somehow store a property in the app.xaml.cs page that would tell the app to exit when the login page is loaded and that property is set to true, but that seems a bit hacky as well.... Any ideas here?

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  • Greasemonkey failing to GM_setValue()

    - by HonoredMule
    I have a Greasemonkey script that uses a Javascript object to maintain some stored objects. It covers quite a large volume of information, but substantially less than it successfully stored and retrieved prior to encountering my problem. One value refuses to save, and I can not for the life of me determine why. The following problem code: Works for other larger objects being maintained. Is presently handling a smaller total amount of data than previously worked. Is not colliding with any function or other object definitions. Can (optionally) successfully save the problem storage key as "{}" during code startup. this.save = function(table) { var tables = this.tables; if(table) tables = [table]; for(i in tables) { logger.log(this[tables[i]]); logger.log(JSON.stringify(this[tables[i]])); GM_setValue(tables[i] + "_" + this.user, JSON.stringify(this[tables[i]])); logger.log(tables[i] + "_" + this.user + " updated"); logger.log(GM_getValue(tables[i] + "_" + this.user)); } } The problem is consistently reproducible and the logging statments produce the following output in Firebug: Object { 54,10 = Object } // Expansion shows complete contents as expected, but there is one oddity--Firebug highlights the array keys in purple instead of the usual black for anonymous objects. {"54,10":{"x":54,"y":10,"name":"Lucky Pheasant"}} // The correctly parsed string. bookmarks_HonoredMule saved undefined I have tried altering the format of the object keys, to no effect. Further narrowing down the issue is that this particular value is successfully saved as an empty object ("{}") during code initialization, but skipping that also does not help. Reloading the page confirms that saving of the nonempty object truly failed. Any idea what could cause this behavior? I've thoroughly explored the possibility of hitting size constraints, but it doesn't appear that can be the problem--as previously mentioned, I've already reduced storage usage. Other larger objects save still, and the total number of objects, which was not high already, has further been reduced by an amount greater than the quantity of data I'm attempting to store here.

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  • avoiding code duplication in Rails 3 models

    - by Dustin Frazier
    I'm working on a Rails 3.1 application where there are a number of different enum-like models that are stored in the database. There is a lot of identical code in these models, as well as in the associated controllers and views. I've solved the code duplication for the controllers and views via a shared parent controller class and the new view/layout inheritance that's part of Rails 3. Now I'm trying to solve the code duplication in the models, and I'm stuck. An example of one of my enum models is as follows: class Format < ActiveRecord::Base has_and_belongs_to_many :videos attr_accessible :name validates :name, presence: true, length: { maximum: 20 } before_destroy :verify_no_linked_videos def verify_no_linked_videos unless self.videos.empty? self.errors[:base] << "Couldn't delete format with associated videos." raise ActiveRecord::RecordInvalid.new self end end end I have four or five other classes with nearly identical code (the association declaration being the only difference). I've tried creating a module with the shared code that they all include (which seems like the Ruby Way), but much of the duplicate code relies on ActiveRecord, so the methods I'm trying to use in the module (validate, attr_accessible, etc.) aren't available. I know about ActiveModel, but that doesn't get me all the way there. I've also tried creating a common, non-persistent parent class that subclasses ActiveRecord::Base, but all of the code I've seen to accomplish this assumes that you won't have subclasses of your non-persistent class that do persist. Any suggestions for how best to avoid duplicating these identical lines of code across many different enum models?

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