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• Approach for authentication and storing user details.

  - by cappuccino

  Hey folks, I am using the Zend Framework but my question is broadly about sessions / databases / auth (PHP MySQL). Currently this is my approach to authentication: 1) User signs in, the details are checked in database. - Standard stuff really. 2) If the details are correct only the user's unique ID is stored in the session and a security token (user unique ID + IP + Browser info + salt). The session in written to the filesystem. I've been reading around and many are saying that storing stuff in sessions is not a good idea, and that you should really only write a unique ID which refers back to the user's details and a security token to prevent session hijacking. So this is the approach i've taken, i use to write the user's details in session, but i've moved that out. Wanted to know your opinions on this. I'm keeping sessions in the filesystem since i don't run on multiple servers, and since i'm only writting a tiny tiny bit of data to sessions, i thought that performance would be greater keeping sessions in the filesystem to reduce load on the database. Once the session is written on authentication, it really is only read-only from then on. 3) The rest of the user's details (like subscription details, permissions, account info etc) are cached in the filesystem (this can always be easily moved to memory if i wanted even more performance). So rather than keeping the user's details in session, the user's details are cached in the file system. I'm using Zend_Cache and the unique cache id is something like md5(/cache/auth/2892), the number is the unique id of the user. I guess the benefit of this method is that once the user is logged in, there is essentially not database queries being run to get the user's details. Just wonder if this approach is better than keeping the whole lot in session... 4) As the user moves throughout the site the only thing that is checked is the ID in the session and the security token. So, overall the first question is 1) is the filesystem more efficient than a database for this purpose 2) have i taken enough security precautions 3) is separating user detail's from the session into a cached file a pointless task? Thanks.

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• DDNS Not Creating Journal (Dhcpd and Named)

  - by user130094

  * EDIT 1 * After monkeying with additional debug logging I see some log entries of interest. 27-Jul-2012 23:45:26.537 general: error: zone example.lan/IN/internal: journal rollforward failed: no more 27-Jul-2012 23:45:26.537 general: error: zone example.lan/IN/internal: not loaded due to errors. ^^^ If I can remedy the above messages I think I'll be good to go ^^^ * EDIT 2 * Grasping at straws I touched a forward and a reverse zone journal file and restarted named. Boom! Works. Despite documentation stating the files are created automatically and what I have seen before... dunno why but that did the trick. Also re-checked perms on the dir the files live in. As certain as I was, they were correct with named having rw. CentOS 6 (final) dhcpd 4.1.1-P1 named BIND 9.8.2rc1-RedHat-9.8.2-0.10.rc1.el6 Basic DHCP and DNS functionality are in place on 192.168.111.2. Clients are assigned addresses as intended and can resolve local DNS names as well as Internet names. My problem is that named's zone journal files are not created. chroot: /var/named/chroot I tried placing the zone files in various directories (/var/named/data, /var/named, /var/named/dynamic - no matter which dir with named owning and wide open perms I now get nowhere). Along the way I, at one point, got a permission denied when named tried to create the journal. Resolved the issue by: chown --recursive named:named /var/named chmod --recursive 777 /var/named The journal was then created and here's where things fell apart. I attempted to tame permissions to something more sane and broke it. Once changed and having restarted named it threw an error indicating the journal was out of sync (or something to that affect)... didn't matter since this is a new setup so I deleted it and now it is not recreated. Now though I see no errors in /var/log/messages, my chrooted /var/log/named.log, or chrooted /var/log/named.debug. I increased the debug level with 'rndc trace' - no love. Increased trace to 10, still nothing. SELinux is disabled... [root@server temp]# sestatus SELinux status: disabled dhcpd.conf... allow client-updates; ddns-update-style interim; subnet 192.168.111.0 netmask 255.255.255.224 { ... key dhcpudpate { algorithm hmac-md5; secret LDJMdPdEZED+/nN/AGO9ZA==; } zone example.lan. { primary 192.168.111.2; key dhcpudpate; } } named.conf... key dhcpudpate { algorithm hmac-md5; secret "LDJMdPdEZED+/nN/AGO9ZA=="; }; zone "example.lan" { type master; file "/var/named/dynamic/example.lan.db"; allow-transfer { none; }; allow-update { key dhcpudpate; }; notify false; check-names ignore; }; The following shows /var/log/named.log output of named starting up - no errors. 27-Jul-2012 21:33:39.349 general: info: zone 111.168.192.in-addr.arpa/IN/internal: loaded serial 2012072601 27-Jul-2012 21:33:39.349 general: info: zone example.lan/IN/internal: loaded serial 2012072501 27-Jul-2012 21:33:39.350 general: info: zone example2.lan/IN/internal: loaded serial 2012072501 27-Jul-2012 21:33:39.350 general: info: zone example3.lan/IN/internal: loaded serial 2012072601 27-Jul-2012 21:33:39.350 general: info: zone example4.lan/IN/internal: loaded serial 2012072501 27-Jul-2012 21:33:39.351 general: info: zone example5.lan/IN/internal: loaded serial 2012072501 27-Jul-2012 21:33:39.351 general: info: managed-keys-zone ./IN/internal: loaded serial 0 27-Jul-2012 21:33:39.351 general: info: zone example.lan/IN/external: loaded serial 2012072501 27-Jul-2012 21:33:39.352 general: info: zone example1.lan/IN/external: loaded serial 2012072501 27-Jul-2012 21:33:39.352 general: info: zone example2.lan/IN/external: loaded serial 2012072501 27-Jul-2012 21:33:39.352 general: info: zone example3.lan/IN/external: loaded serial 2012072501 27-Jul-2012 21:33:39.353 general: info: managed-keys-zone ./IN/external: loaded serial 0 27-Jul-2012 21:33:39.353 general: notice: running 27-Jul-2012 21:34:03.825 general: info: received control channel command 'trace 10' 27-Jul-2012 21:34:03.825 general: info: debug level is now 10 ...and /var/log/messages for a named start... Jul 27 23:02:04 server named[9124]: ---------------------------------------------------- Jul 27 23:02:04 server named[9124]: BIND 9 is maintained by Internet Systems Consortium, Jul 27 23:02:04 server named[9124]: Inc. (ISC), a non-profit 501(c)(3) public-benefit Jul 27 23:02:04 server named[9124]: corporation. Support and training for BIND 9 are Jul 27 23:02:04 server named[9124]: available at https://www.isc.org/support Jul 27 23:02:04 server named[9124]: ---------------------------------------------------- Jul 27 23:02:04 server named[9124]: adjusted limit on open files from 4096 to 1048576 Jul 27 23:02:04 server named[9124]: found 2 CPUs, using 2 worker threads Jul 27 23:02:04 server named[9124]: using up to 4096 sockets Jul 27 23:02:04 server named[9124]: loading configuration from '/etc/named.conf' Jul 27 23:02:04 server named[9124]: using default UDP/IPv4 port range: [1024, 65535] Jul 27 23:02:04 server named[9124]: using default UDP/IPv6 port range: [1024, 65535] Jul 27 23:02:04 server named[9124]: listening on IPv4 interface eth0, 192.168.111.2#53 Jul 27 23:02:04 server named[9124]: generating session key for dynamic DNS Jul 27 23:02:04 server named[9124]: sizing zone task pool based on 12 zones Jul 27 23:02:04 server named[9124]: set up managed keys zone for view internal, file 'dynamic/3bed2cb3a3acf7b6a8ef408420cc682d5520e26976d354254f528c965612054f.mkeys' Jul 27 23:02:04 server named[9124]: set up managed keys zone for view external, file 'dynamic/3c4623849a49a53911c4a3e48d8cead8a1858960bccdea7a1b978d73ec2f06d7.mkeys' Jul 27 23:02:04 server named[9124]: command channel listening on 127.0.0.1#953 What can I do to troubleshoot this further? It almost seems as though dhcpd is not triggering the update. Maybe I should troubleshoot here and, if so, how? Many thanks.

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• SQL Server CTE referred in self joins slow

  - by Kharlos Dominguez

  Hello, I have written a table-valued UDF that starts by a CTE to return a subset of the rows from a large table. There are several joins in the CTE. A couple of inner and one left join to other tables, which don't contain a lot of rows. The CTE has a where clause that returns the rows within a date range, in order to return only the rows needed. I'm then referencing this CTE in 4 self left joins, in order to build subtotals using different criterias. The query is quite complex but here is a simplified pseudo-version of it WITH DataCTE as ( SELECT [columns] FROM table INNER JOIN table2 ON [...] INNER JOIN table3 ON [...] LEFT JOIN table3 ON [...] ) SELECT [aggregates_columns of each subset] FROM DataCTE Main LEFT JOIN DataCTE BananasSubset ON [...] AND Product = 'Bananas' AND Quality = 100 LEFT JOIN DataCTE DamagedBananasSubset ON [...] AND Product = 'Bananas' AND Quality < 20 LEFT JOIN DataCTE MangosSubset ON [...] GROUP BY [ I have the feeling that SQL Server gets confused and calls the CTE for each self join, which seems confirmed by looking at the execution plan, although I confess not being an expert at reading those. I would have assumed SQL Server to be smart enough to only perform the data retrieval from the CTE only once, rather than do it several times. I have tried the same approach but rather than using a CTE to get the subset of the data, I used the same select query as in the CTE, but made it output to a temp table instead. The version referring the CTE version takes 40 seconds. The version referring the temp table takes between 1 and 2 seconds. Why isn't SQL Server smart enough to keep the CTE results in memory? I like CTEs, especially in this case as my UDF is a table-valued one, so it allowed me to keep everything in a single statement. To use a temp table, I would need to write a multi-statement table valued UDF, which I find a slightly less elegant solution. Did some of you had this kind of performance issues with CTE, and if so, how did you get them sorted? Thanks, Kharlos

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• Performing full screen grab in windows

  - by Steven Lu

  I am working an idea that involves getting a full capture of the screen including windows and apps, analyzing it, and then drawing items back onto the screen, as an overlay. I want to learn image processing techniques and I could get lots of data to work with if I can directly access the Windows screen. I could use this to build automation tools the likes of which have never been seen before. More on that later. I have full screen capture working for the most part. HWND hwind = GetDesktopWindow(); HDC hdc = GetDC(hwind); int resx = GetSystemMetrics(SM_CXSCREEN); int resy = GetSystemMetrics(SM_CYSCREEN); int BitsPerPixel = GetDeviceCaps(hdc,BITSPIXEL); HDC hdc2 = CreateCompatibleDC(hdc); BITMAPINFO info; info.bmiHeader.biSize = sizeof(BITMAPINFOHEADER); info.bmiHeader.biWidth = resx; info.bmiHeader.biHeight = resy; info.bmiHeader.biPlanes = 1; info.bmiHeader.biBitCount = BitsPerPixel; info.bmiHeader.biCompression = BI_RGB; void *data; hbitmap = CreateDIBSection(hdc2,&info,DIB_RGB_COLORS,(void**)&data,0,0); SelectObject(hdc2,hbitmap); Once this is done, I can call this repeatedly: BitBlt(hdc2,0,0,resx,resy,hdc,0,0,SRCCOPY); The cleanup code (I have no idea if this is correct): DeleteObject(hbitmap); ReleaseDC(hwind,hdc); if (hdc2) { DeleteDC(hdc2); } Every time BitBlt is called it grabs the screen and saves it in memory I can access thru data. Performance is somewhat satisfactory. BitBlt executes in 50 milliseconds (sometimes as low as 33ms) at 1920x1200x32. What surprises me is that when I switch display mode to 16 bit, 1920x1200x16, either through my graphics settings beforehand, or by using ChangeDisplaySettings, I get a massively improved screen grab time between 1ms and 2ms, which cannot be explained by the factor of two reduction in bit-depth. Using CreateDIBSection (as above) offers a significant speed up when in 16-bit mode, compared to if I set up with CreateCompatibleBitmap (6-7ms/f). Does anybody know why dropping to 16bit causes such a speed increase? Is there any hope for me to grab 32bit at such speeds? if not for the color depth, but for not forcing a change of screen buffer modes and the awful flickering.

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• Help with C# program design implementation: multiple array of lists or a better way?

  - by Bob

  I'm creating a 2D tile-based RPG in XNA and am in the initial design phase. I was thinking of how I want my tile engine to work and came up with a rough sketch. Basically I want a grid of tiles, but at each tile location I want to be able to add more than one tile and have an offset. I'd like this so that I could do something like add individual trees on the world map to give more flair. Or set bottles on a bar in some town without having to draw a bunch of different bar tiles with varying bottles. But maybe my reach is greater than my grasp. I went to implement the idea and had something like this in my Map object: List<Tile>[,] Grid; But then I thought about it. Let's say I had a world map of 200x200, which would actually be pretty small as far as RPGs go. That would amount to 40,000 Lists. To my mind I think there has to be a better way. Now this IS pre-mature optimization. I don't know if the way I happen to design my maps and game will be able to handle this, but it seems needlessly inefficient and something that could creep up if my game gets more complex. One idea I have is to make the offset and the multiple tiles optional so that I'm only paying for them when needed. But I'm not sure how I'd do this. A multiple array of objects? object[,] Grid; So here's my criteria: A 2D grid of tile locations Each tile location has a minimum of 1 tile, but can optionally have more Each extra tile can optionally have an x and y offset for pinpoint placement Can anyone help with some ideas for implementing such a design (don't need it done for me, just ideas) while keeping memory usage to a minimum? If you need more background here's roughly what my Map and Tile objects amount to: public struct Map { public Texture2D Texture; public List<Rectangle> Sources; //Source Rectangles for where in Texture to get the sprite public List<Tile>[,] Grid; } public struct Tile { public int Index; //Where in Sources to find the source Rectangle public int X, Y; //Optional offsets }

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• Issues declaring already existing NSMutableArray in new class

  - by Graeme

  I have a class (DataImporter) which has the code to download an RSS feed. I also have a view and separate class (TableView) which displays the data in a UITableView and starts the parsing process, storing parsed information in an NSMutableArray (items) which is located in the (TableView) subclass. Now I wish to add a UIMapView which displays the items in the (items) NSMutableArray. Herein lies the issue - I need to somehow get the data from the (items) NSMutableArray into the new (mapView) subclass which I'm struggling with - and I preferably don't want to have to create a new class to download the data again for the mapView class when it already is in the applications memory. Is there a way I can transfer the information from the NSMutableArray (items) class to the (mapView) class (i.e. how do I declare the NSMutableArray in the (mapView) class)? Here's a overview of how the system works: App opened Data downloaded (using DataImporter class) when (TableView) viewDidLoad runs Data stored in NSMutableArray accessible by the (TableView) class And from here I need to access and declare the array from a new (mapView) class. Any help greatly appreciated, thanks. Code for viewDidLoad MapKit: Data *data = nil; NSString *ilocation = [data locations]; NSString *ilocation2 = @"New Zealand"; NSString *inewlString; inewlString = [ilocation stringByAppendingString:ilocation2]; NSLog(@"inewlString=%@",inewlString); if(forwardGeocoder == nil) { forwardGeocoder = [[BSForwardGeocoder alloc] initWithDelegate:self]; } // Forward geocode! [forwardGeocoder findLocation: inewlString]; Code for parsing data into original NSMutable Array: - (void)beginParsing { NSLog(@"Parsing has begun"); //self.navigationItem.rightBarButtonItem.enabled = NO; // Allocate the array for song storage, or empty the results of previous parses if (incidents == nil) { NSLog(@"Grabbing array"); self.datas = [NSMutableArray array]; } else { [datas removeAllObjects]; [self.tableView reloadData]; } // Create the parser, set its delegate, and start it. self.parser = [[DataImporter alloc] init]; parser.delegate = self; [parser start]; }

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• Why an object declared in method is subject to garbage collection before the method returns?

  - by SiLent SoNG

  Consider an object declared in a method: public void foo() { final Object obj = new Object(); // A long run job that consumes tons of memory and // triggers garbage collection } Will obj be subject to garbage collection before foo() returns? UPDATE: Previously I thought obj is not subject to garbage collection until foo() returns. However, today I find myself wrong. I have spend several hours in fixing a bug and finally found the problem is caused by obj garbage collected! Can anyone explain why this happens? And if I want obj to be pinned how to achieve it? Here is the code that has problem. public class Program { public static void main(String[] args) throws Exception { String connectionString = "jdbc:mysql://<whatever>"; // I find wrap is gc-ed somewhere SqlConnection wrap = new SqlConnection(connectionString); Connection con = wrap.currentConnection(); Statement stmt = con.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY); stmt.setFetchSize(Integer.MIN_VALUE); ResultSet rs = stmt.executeQuery("select instance_id, doc_id from crawler_archive.documents"); while (rs.next()) { int instanceID = rs.getInt(1); int docID = rs.getInt(2); if (docID % 1000 == 0) { System.out.println(docID); } } rs.close(); //wrap.close(); } } After running the Java program, it will print the following message before it crashes: 161000 161000 ******************************** Finalizer CALLED!! ******************************** ******************************** Close CALLED!! ******************************** 162000 Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: And here is the code of class SqlConnection: class SqlConnection { private final String connectionString; private Connection connection; public SqlConnection(String connectionString) { this.connectionString = connectionString; } public synchronized Connection currentConnection() throws SQLException { if (this.connection == null || this.connection.isClosed()) { this.closeConnection(); this.connection = DriverManager.getConnection(connectionString); } return this.connection; } protected void finalize() throws Throwable { try { System.out.println("********************************"); System.out.println("Finalizer CALLED!!"); System.out.println("********************************"); this.close(); } finally { super.finalize(); } } public void close() { System.out.println("********************************"); System.out.println("Close CALLED!!"); System.out.println("********************************"); this.closeConnection(); } protected void closeConnection() { if (this.connection != null) { try { connection.close(); } catch (Throwable e) { } finally { this.connection = null; } } } }

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• Class template specializations with shared functionality

  - by Thomas

  I'm writing a simple maths library with a template vector type: template<typename T, size_t N> class Vector { public: Vector<T, N> &operator+=(Vector<T, N> const &other); // ... more operators, functions ... }; Now I want some additional functionality specifically for some of these. Let's say I want functions x() and y() on Vector<T, 2> to access particular coordinates. I could create a partial specialization for this: template<typename T> class Vector<T, 3> { public: Vector<T, 3> &operator+=(Vector<T, 3> const &other); // ... and again all the operators and functions ... T x() const; T y() const; }; But now I'm repeating everything that already existed in the generic template. I could also use inheritance. Renaming the generic template to VectorBase, I could do this: template<typename T, size_t N> class Vector : public VectorBase<T, N> { }; template<typename T> class Vector<T, 3> : public VectorBase<T, 3> { public: T x() const; T y() const; }; However, now the problem is that all operators are defined on VectorBase, so they return VectorBase instances. These cannot be assigned to Vector variables: Vector<float, 3> v; Vector<float, 3> w; w = 5 * v; // error: no conversion from VectorBase<float, 3> to Vector<float, 3> I could give Vector an implicit conversion constructor to make this possible: template<typename T, size_t N> class Vector : public VectorBase<T, N> { public: Vector(VectorBase<T, N> const &other); }; However, now I'm converting from Vector to VectorBase and back again. Even though the types are the same in memory, and the compiler might optimize all this away, it feels clunky and I don't really like to have potential run-time overhead for what is essentially a compile-time problem. Is there any other way to solve this?

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• Mysql - help me optimize this query (improved question)

  - by sandeepan-nath

  About the system: - There are tutors who create classes and packs - A tags based search approach is being followed.Tag relations are created when new tutors register and when tutors create packs (this makes tutors and packs searcheable). For details please check the section How tags work in this system? below. Following is the concerned query SELECT SUM(DISTINCT( t.tag LIKE "%Dictatorship%" )) AS key_1_total_matches, SUM(DISTINCT( t.tag LIKE "%democracy%" )) AS key_2_total_matches, COUNT(DISTINCT( od.id_od )) AS tutor_popularity, CASE WHEN ( IF(( wc.id_wc > 0 ), ( wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date > '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'classes_published', CASE WHEN ( IF(( lp.id_lp > 0 ), ( lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ), 0) ) THEN 1 ELSE 0 END AS 'packs_published', td . *, u . * FROM tutor_details AS td JOIN users AS u ON u.id_user = td.id_user LEFT JOIN learning_packs_tag_relations AS lptagrels ON td.id_tutor = lptagrels.id_tutor LEFT JOIN learning_packs AS lp ON lptagrels.id_lp = lp.id_lp LEFT JOIN learning_packs_categories AS lpc ON lpc.id_lp_cat = lp.id_lp_cat LEFT JOIN learning_packs_categories AS lpcp ON lpcp.id_lp_cat = lpc.id_parent LEFT JOIN learning_pack_content AS lpct ON ( lp.id_lp = lpct.id_lp ) LEFT JOIN webclasses_tag_relations AS wtagrels ON td.id_tutor = wtagrels.id_tutor LEFT JOIN webclasses AS wc ON wtagrels.id_wc = wc.id_wc LEFT JOIN learning_packs_categories AS wcc ON wcc.id_lp_cat = wc.id_wp_cat LEFT JOIN learning_packs_categories AS wccp ON wccp.id_lp_cat = wcc.id_parent LEFT JOIN order_details AS od ON td.id_tutor = od.id_author LEFT JOIN orders AS o ON od.id_order = o.id_order LEFT JOIN tutors_tag_relations AS ttagrels ON td.id_tutor = ttagrels.id_tutor JOIN tags AS t ON ( t.id_tag = ttagrels.id_tag ) OR ( t.id_tag = lptagrels.id_tag ) OR ( t.id_tag = wtagrels.id_tag ) WHERE ( u.country = 'IE' OR u.country IN ( 'INT' ) ) AND CASE WHEN ( ( t.id_tag = lptagrels.id_tag ) AND ( lp.id_lp 0 ) ) THEN lp.id_status = 1 AND lp.published = 1 AND lpcp.status = 1 AND ( lpcp.country_code = 'IE' OR lpcp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( ( t.id_tag = wtagrels.id_tag ) AND ( wc.id_wc 0 ) ) THEN wc.wc_api_status = 1 AND wc.wc_type = 0 AND wc.class_date '2010-06-01 22:00:56' AND wccp.status = 1 AND ( wccp.country_code = 'IE' OR wccp.country_code IN ( 'INT' ) ) ELSE 1 END AND CASE WHEN ( od.id_od 0 ) THEN od.id_author = td.id_tutor AND o.order_status = 'paid' AND CASE WHEN ( od.id_wc 0 ) THEN od.can_attend_class = 1 ELSE 1 END ELSE 1 END GROUP BY td.id_tutor HAVING key_1_total_matches = 1 AND key_2_total_matches = 1 ORDER BY tutor_popularity DESC, u.surname ASC, u.name ASC LIMIT 0, 20 The problem The results returned by the above query are correct (AND logic working as per expectation), but the time taken by the query rises alarmingly for heavier data and for the current data I have it is like 25 seconds as against normal query timings of the order of 0.005 - 0.0002 seconds, which makes it totally unusable. It is possible that some of the delay is being caused because all the possible fields have not yet been indexed. The tag field of tags table is indexed. Is there something faulty with the query? What can be the reason behind 20+ seconds of execution time? How tags work in this system? When a tutor registers, tags are entered and tag relations are created with respect to tutor's details like name, surname etc. When a Tutors create packs, again tags are entered and tag relations are created with respect to pack's details like pack name, description etc. tag relations for tutors stored in tutors_tag_relations and those for packs stored in learning_packs_tag_relations. All individual tags are stored in tags table. The explain query output:- Please see this screenshot - http://www.test.examvillage.com/Explain_query.jpg

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• Few iPhone noob questions

  - by mshsayem

  Why should I declare local variables as 'static' inside a method? Like: static NSString *cellIdentifier = @"Cell"; Is it a performance advantage? (I know what 'static' does; in C context) What does this syntax mean?[someObj release], someObj = nil; Two statements? Why should I assign nil again? Is not 'release' enough? Should I do it for all objects I allocate/own? Or for just view objects? Why does everyone copy NSString, but retains other objects (in property declaration)? Yes, NSStrings can be changed, but other objects can be changed also, right? Then why 'copy' for just NSString, not for all? Is it just a defensive convention? Shouldn't I release constant NSString? Like here:NSString *CellIdentifier = @"Cell"; Why not? Does the compiler allocate/deallocate it for me? In some tutorial application I observed these (Built with IB): Properties(IBOutlet, with same ivar name): window, someLabel, someTextField, etc etc... In the dealloc method, although the window ivar was released, others were not. My question is: WHY? Shouldn't I release other ivars(labels, textField) as well? Why not? Say, I have 3 cascaded drop-down lists. I mean, based on what is selected on the first list, 2nd list is populated and based on what is selected on the second list, 3rd list is populated. What UI components can reflect this best? How is drop-down list presented in iPhone UI? Tableview with UIPicker? When should I update the 2nd, 3rd list? Or just three labels which have touch events? Can you give me some good example tutorials about Core-Data? (Not just simple data fetching and storing on 2/3 tables with 1/2 relationship) How can I know whether my app is leaking memory? Any tools?

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• Neo4j 1.9.4 (REST Server,CYPHER) performance issue

  - by user2968943

  I have Neo4j 1.9.4 installed on 24 core 24Gb ram (centos) machine and for most queries CPU usage spikes goes to 200% with only few concurrent requests. Domain: some sort of social application where few types of nodes(profiles) with 3-30 text/array properties and 36 relationship types with at least 3 properties. Most of nodes currently has ~300-500 relationships. Current data set footprint(from console): LogicalLogSize=4294907 (32MB) ArrayStoreSize=1675520 (12MB) NodeStoreSize=1342170 (10MB) PropertyStoreSize=1739548 (13MB) RelationshipStoreSize=6395202 (48MB) StringStoreSize=1478400 (11MB) which is IMHO really small. most queries looks like this one(with more or less WITH .. MATCH .. statements and few queries with variable length relations but the often fast): START targetUser=node({id}), currentUser=node({current}) MATCH targetUser-[contact:InContactsRelation]->n, n-[:InLocationRelation]->l, n-[:InCategoryRelation]->c WITH currentUser, targetUser,n, l,c, contact.fav is not null as inFavorites MATCH n<-[followers?:InContactsRelation]-() WITH currentUser, targetUser,n, l,c,inFavorites, COUNT(followers) as numFollowers RETURN id(n) as id, n.name? as name, n.title? as title, n._class as _class, n.avatar? as avatar, n.avatar_type? as avatar_type, l.name as location__name, c.name as category__name, true as isInContacts, inFavorites as isInFavorites, numFollowers it runs in ~1s-3s(for first run) and ~1s-70ms (for consecutive and it depends on query) and there is about 5-10 queries runs for each impression. Another interesting behavior is when i try run query from console(neo4j) on my local machine many consecutive times(just press ctrl+enter for few seconds) it has almost constant execution time but when i do it on server it goes slower exponentially and i guess it somehow related with my problem. Problem: So my problem is that neo4j is very CPU greedy(for 24 core machine its may be not an issue but its obviously overkill for small project). First time i used AWS EC2 m1.large instance but over all performance was bad, during testing, CPU always was over 100%. Some relevant parts of configuration: neostore.nodestore.db.mapped_memory=1280M wrapper.java.maxmemory=8192 note: I already tried configuration where all memory related parameters where HIGH and it didn't worked(no change at all). Question: Where to digg? configuration? scheme? queries? what i'm doing wrong? if need more info(logs, configs) just ask ;)

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• writing XML with Xerces 3.0.1 and C++ on windows

  - by Jon

  Hi, i have the following function i wrote to create an XML file using Xerces 3.0.1, if i call this function with a filePath of "foo.xml" or "../foo.xml" it works great, but if i pass in "c:/foo.xml" then i get an exception on this line XMLFormatTarget *formatTarget = new LocalFileFormatTarget(targetPath); can someone explain why my code works for relative paths, but not absolute paths please? many thanks. const int ABSOLUTE_PATH_FILENAME_PREFIX_SIZE = 9; void OutputXML(xercesc::DOMDocument* pmyDOMDocument, std::string filePath) { //Return the first registered implementation that has the desired features. In this case, we are after a DOM implementation that has the LS feature... or Load/Save. DOMImplementation *implementation = DOMImplementationRegistry::getDOMImplementation(L"LS"); // Create a DOMLSSerializer which is used to serialize a DOM tree into an XML document. DOMLSSerializer *serializer = ((DOMImplementationLS*)implementation)->createLSSerializer(); // Make the output more human readable by inserting line feeds. if (serializer->getDomConfig()->canSetParameter(XMLUni::fgDOMWRTFormatPrettyPrint, true)) serializer->getDomConfig()->setParameter(XMLUni::fgDOMWRTFormatPrettyPrint, true); // The end-of-line sequence of characters to be used in the XML being written out. serializer->setNewLine(XMLString::transcode("\r\n")); // Convert the path into Xerces compatible XMLCh*. XMLCh *tempFilePath = XMLString::transcode(filePath.c_str()); // Calculate the length of the string. const int pathLen = XMLString::stringLen(tempFilePath); // Allocate memory for a Xerces string sufficent to hold the path. XMLCh *targetPath = (XMLCh*)XMLPlatformUtils::fgMemoryManager->allocate((pathLen + ABSOLUTE_PATH_FILENAME_PREFIX_SIZE) * sizeof(XMLCh)); // Fixes a platform dependent absolute path filename to standard URI form. XMLString::fixURI(tempFilePath, targetPath); // Specify the target for the XML output. XMLFormatTarget *formatTarget = new LocalFileFormatTarget(targetPath); //XMLFormatTarget *myFormTarget = new StdOutFormatTarget(); // Create a new empty output destination object. DOMLSOutput *output = ((DOMImplementationLS*)implementation)->createLSOutput(); // Set the stream to our target. output->setByteStream(formatTarget); // Write the serialized output to the destination. serializer->write(pmyDOMDocument, output); // Cleanup. serializer->release(); XMLString::release(&tempFilePath); delete formatTarget; output->release(); }

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• Saving data in custom class via AppDelegate

  - by redspike

  I can't seem to save data to a custom instance object in my AppDelegate. My custom class is very simple and is as follows: Person.h ... @interface Person : NSObject { int _age; } - (void) setAge: (int) age; - (int) age; @end Person.m #import "Person.h" @implementation Person - (void) setAge:(int) age { _age = age; } - (int) age { return _age; } @end I then create an instance of Person in the AppDelegate class: AppDelegate.h @class Person; @interface AccuTaxAppDelegate : NSObject <UIApplicationDelegate> { ... Person *person; } ... @property (nonatomic, retain) Person *person; @end AppDelegate.m ... #import "Person.h" @implementation AccuTaxAppDelegate ... @synthesize person; - (void)applicationDidFinishLaunching:(UIApplication *)application { // Override point for customization after app launch [window addSubview:[navigationController view]]; [window makeKeyAndVisible]; } - (void)applicationWillTerminate:(UIApplication *)application { // Save data if appropriate } #pragma mark - #pragma mark Memory management - (void)dealloc { [navigationController release]; [window release]; [person release]; [super dealloc]; } @end Finally, in my ViewController code I grab a handle on AppDelegate and then grab the person instance, but when I try to save the age it doesn't seem to work: MyViewController ... - (void)textFieldDidEndEditing:(UITextField *)textField { NSString *textAge = [textField text]; int age = [textAge intValue]; NSLog(@"Age from text field::%i", age); AppDelegate *appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate; Person *myPerson = (Person *)[appDelegate person]; NSLog(@"Age before setting: %i", [myPerson age]); [myPerson setAge:age]; NSLog(@"Age after setting: %i", [myPerson age]); [textAge release]; } ... The output of the above NSLogs are: [Session started at 2010-05-04 18:29:22 +0100.] 2010-05-04 18:29:28.260 AccuTax[16235:207] Age in text field:25 2010-05-04 18:29:28.262 AccuTax[16235:207] Age before setting: 0 2010-05-04 18:29:28.263 AccuTax[16235:207] Age after setting: 0 Any ideas why 'age' isn't being stored? I'm relatively new to Obj-C so please forgive me if I'm missing something very simple!

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• IEnumerable<T> ToArray usage, is it a copy or a pointer?

  - by Daniel

  I am parsing an arbitrary length byte array that is going to be passed around to a few different layers of parsing. Each parser creates a Header and a Packet payload just like any ordinary encapsulation. And my problem lies in how the encapsulation holds its packet byte array payload. Say i have a 100 byte array, and it has 3 levels of encapsulation. 3 packet objects will be created and i want to set the payload of these packets to the corresponding position in the byte array of the packet. For example lets say the payload size is 20 for all levels, then imagine it has a public byte[] Payload on each object. However the problem is that this byte[] Payload is a copy of the original 100 bytes. So i'm going to end up with 160 bytes in memory instead of 100. If it were in c++ i could just easily use a pointer however i'm writing this in c#. So i created the following class: public class PayloadSegment<T> : IEnumerable<T> { public readonly T[] Array; public readonly int Offset; public readonly int Count; public PayloadSegment(T[] array, int offset, int count) { this.Array = array; this.Offset = offset; this.Count = count; } public T this[int index] { get { if (index < 0 || index >= this.Count) throw new IndexOutOfRangeException(); else return Array[Offset + index]; } set { if (index < 0 || index >= this.Count) throw new IndexOutOfRangeException(); else Array[Offset + index] = value; } } public IEnumerator<T> GetEnumerator() { for (int i = Offset; i < Offset + Count; i++) yield return Array[i]; } System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { IEnumerator<T> enumerator = this.GetEnumerator(); while (enumerator.MoveNext()) { yield return enumerator.Current; } } } This way i can simply reference a position inside the original byte array but use positional indexing. However if i do something like: PayloadSegment<byte> something = new PayloadSegment<byte>(someArray, 5, 10); byte[] somethingArray = something.ToArray(); Will the somethingArray be a copy of the bytes, or a reference to the original PayloadSegment which in turn is a reference to the original byte array? Sorry it was hard to word this lol _<

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• Do You Really Know Your Programming Languages?

  - by Kristopher Johnson

  I am often amazed at how little some of my colleagues know or care about their craft. Something that constantly frustrates me is that people don't want to learn any more than they need to about the programming languages they use every day. Many programmers seem content to learn some pidgin sub-dialect, and stick with that. If they see a keyword or construct that they aren't familiar with, they'll complain that the code is "tricky." What would you think of a civil engineer who shied away from calculus because it had "all those tricky math symbols?" I'm not suggesting that we all need to become "language lawyers." But if you make your living as a programmer, and claim to be a competent user of language X, then I think at a minimum you should know the following: Do you know the keywords of the language and what they do? What are the valid syntactic forms? How are memory, files, and other operating system resources managed? Where is the official language specification and library reference for the language? The last one is the one that really gets me. Many programmers seem to have no idea that there is a "specification" or "standard" for any particular language. I still talk to people who think that Microsoft invented C++, and that if a program doesn't compile under VC6, it's not a valid C++ program. Programmers these days have it easy when it comes to obtaining specs. Newer languages like C#, Java, Python, Ruby, etc. all have their documentation available for free from the vendors' web sites. Older languages and platforms often have standards controlled by standards bodies that demand payment for specs, but even that shouldn't be a deterrent: the C++ standard is available from ISO for $30 (and why am I the only person I know who has a copy?). Programming is hard enough even when you do know the language. If you don't, I don't see how you have a chance. What do the rest of you think? Am I right, or should we all be content with the typical level of programming language expertise? Update: Several great comments here. Thanks. A couple of people hit on something that I didn't think about: What really irks me is not the lack of knowledge, but the lack of curiosity and willingness to learn. It seems some people don't have any time to hone their craft, but they have plenty of time to write lots of bad code. And I don't expect people to be able to recite a list of keywords or EBNF expressions, but I do expect that when they see some code, they should have some inkling of what it does. Few people have complete knowledge of every dark corner of their language or platform, but everyone should at least know enough that when they see something unfamiliar, they will know how to get whatever additional information they need to understand it.

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• Optimizing Vector elements swaps using CUDA

  - by Orion Nebula

  Hi all, Since I am new to cuda .. I need your kind help I have this long vector, for each group of 24 elements, I need to do the following: for the first 12 elements, the even numbered elements are multiplied by -1, for the second 12 elements, the odd numbered elements are multiplied by -1 then the following swap takes place: Graph: because I don't yet have enough points, I couldn't post the image so here it is: http://www.freeimagehosting.net/image.php?e4b88fb666.png I have written this piece of code, and wonder if you could help me further optimize it to solve for divergence or bank conflicts .. //subvector is a multiple of 24, Mds and Nds are shared memory _shared_ double Mds[subVector]; _shared_ double Nds[subVector]; int tx = threadIdx.x; int tx_mod = tx ^ 0x0001; int basex = __umul24(blockDim.x, blockIdx.x); Mds[tx] = M.elements[basex + tx]; __syncthreads(); // flip the signs if (tx < (tx/24)*24 + 12) { //if < 12 and even if ((tx & 0x0001)==0) Mds[tx] = -Mds[tx]; } else if (tx < (tx/24)*24 + 24) { //if >12 and < 24 and odd if ((tx & 0x0001)==1) Mds[tx] = -Mds[tx]; } __syncthreads(); if (tx < (tx/24)*24 + 6) { //for the first 6 elements .. swap with last six in the 24elements group (see graph) Nds[tx] = Mds[tx_mod + 18]; Mds [tx_mod + 18] = Mds [tx]; Mds[tx] = Nds[tx]; } else if (tx < (tx/24)*24 + 12) { // for the second 6 elements .. swp with next adjacent group (see graph) Nds[tx] = Mds[tx_mod + 6]; Mds [tx_mod + 6] = Mds [tx]; Mds[tx] = Nds[tx]; } __syncthreads(); Thanks in advance ..

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• JPA2 adding referential contraint to table complicates criteria query with lazy fetch, need advice

  - by Quaternion

  Following is a lot of writing for what I feel is a pretty simple issue. Root of issue is my ignorance, not looking so much for code but advice. Table: Ininvhst (Inventory-schema inventory history) column ihtran (inventory history transfer code) using an old entity mapping I have: @Basic(optional = false) @Column(name = "IHTRAN") private String ihtran; ihtran is really a foreign key to table Intrnmst ("Inventory Transfer Master" which contains a list of "transfer codes"). This was not expressed in the database so placed a referential constraint on Ininvhst re-generating JPA2 entity classes produced: @JoinColumn(name = "IHTRAN", referencedColumnName = "TMCODE", nullable = false) @ManyToOne(optional = false) private Intrnmst intrnmst; Now previously I was using JPA2 to select the records/(Ininvhst entities) from the Ininvhst table where "ihtran" was one of a set of values. I used in.value() to do this... here is a snippet: cq = cb.createQuery(Ininvhst.class); ... In in = cb.in(transactionType); //Get in expression for transacton types for (String s : transactionTypes) { //has a value in = in.value(s);//check if the strings we are looking for exist in the transfer master } predicateList.add(in); My issue is that the Ininvhst used to contain a string called ihtran but now it contains Ininvhst... So I now need a path expression: this.predicateList = new ArrayList<Predicate>(); if (transactionTypes != null && transactionTypes.size() > 0) { //list of strings has some values Path<Intrnmst> intrnmst = root.get(Ininvhst_.intrnmst); //get transfermaster from Ininvhst Path<String> transactionType = intrnmst.get(Intrnmst_.tmcode); //get transaction types from transfer master In<String> in = cb.in(transactionType); //Get in expression for transacton types for (String s : transactionTypes) { //has a value in = in.value(s);//check if the strings we are looking for exist in the transfer master } predicateList.add(in); } Can I add ihtran back into the entity along with a join column that is both references "IHTRAN"? Or should I use a projection to somehow return Ininvhst along with the ihtran string which is now part of the Intrnmst entity. Or should I use a projection to return Ininvhst and somehow limit Intrnmst just just the ihtran string. Further information: I am using the resulting list of selected Ininvhst objects in a web application, the class which contains the list of Ininvhst objects is transformed into a json object. There are probably quite a few serialization methods that would navigate the object graph the problem is that my current fetch strategy is lazy so it hits the join entity (Intrnmst intrnmst) and there is no Entity Manager available at that point. At this point I have prevented the object from serializing the join column but now I am missing a critical piece of data. I think I've said too much but not knowing enough I don't know what you JPA experts need. What I would like is my original object to have both a string object and be able to join on the same column (ihtran) and have it as a string too, but if this isn't possible or advisable I want to hear what I should do and why. Pseudo code/English is more than fine.

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• System user authentication via web interface [closed]

  - by donodarazao

  Background: We have one pretty slow and expensive satellite Internet connection that is shared in a network with 5-50 users. To limit traffic, users shall pay a certain sum of money per hour. Routing and traffic accounting on user basis is done by a opensuse 10.3 server. Login is done via pppoe, and for each connection, username, bytes_sent, bytes_rcvd, start_time, end_time,etc are written into a mysql database. Now it was decided that we want to change from time-based to volume-based pricing. As the original developer who installed the system a couple of years ago isn't available, I'm trying to do the changes. Although I'm absolutely new to all this, there is some progress. However, there's one point I'm absolutely stuck. Up to now, only administrators can access connection details and billing information via a web interface. But as volume-based prices are less transparent to users than time-based prices, it is essential that users themselves can check their connections and how much they cost via the web interface. For this, we need some kind of user authentication. Actual question: How to develop such a user authentication? Every user has a linux system user account. With this user name and password, connection to the pppoe-server is made by the client machines. I thought about two possibles ways to authenticate users: First possibility: Users type username and password in a form. This is then somehow checked. We already have to possibilities to change passwords via the web interface. Here are parts of the code: Part of the Perl script the homepage is linked to: #!/usr/bin/perl use CGI; use CGI::Carp qw(fatalsToBrowser); use lib '../lib'; use own_perl_module; my @error; my $data; $query = new CGI; $username = $query->param('username') || ''; $oldpasswd = $query->param('oldpasswd') || ''; $passwd = $query->param('passwd') || ''; $passwd2 = $query->param('passwd2') || ''; own_perl_module::connect(); if ($query->param('submit')) { my $benutzer = own_perl_module::select_benutzer(username => $username) or push @error, "user not exists"; push @error, "your password?!?" unless $passwd; unless (@error) { own_perl_module::update_benutzer($benutzer->{id}, { oldpasswd => $oldpasswd, passwd => $passwd, passwd2 => $passwd2 }, error => \@error) and push @error, "Password changed."; } } Here's part of the sub update_benutzer in the own_perl_module: if ($dat-{passwd} ne '') { my $username = $dat-{username} || $select-{username}; my $system = "./chpasswd.pl '$username' '$dat-{passwd}'" . (defined($dat-{oldpasswd}) ? " '$dat-{oldpasswd}'" : undef); my $answer = $system; if ($? != 0) { chomp($answer); push @$error, $answer || "error changing password ($?)"; Here's chpasswd.pl: #!/usr/bin/perl use FileHandle; use IPC::Open3; local $username = shift; local $passwd = shift; local $oldpasswd = shift; local $chat = { 'Old Password: $' => sub { print POUT "$oldpasswd\n"; }, 'New password: $' => sub { print POUT "$passwd\n"; }, 'Re-enter new password: $' => sub { print POUT "$passwd\n"; }, '(.*)\n$' => sub { print "$1\n"; exit 1; } }; local $/ = \1; my $command; if (defined($oldpasswd)) { $command = "sudo -u '$username' /usr/bin/passwd"; } else { $command = "sudo /usr/bin/passwd '$username'"; } $pid = open3(\*POUT, \*PIN, \*PERR, $command) or die; my $buffer; LOOP: while($_ = <PERR>) { $buffer .= $_; foreach (keys(%$chat)) { if ($buffer =~ /$_/i) { $buffer = undef; &{$chat->{$_}}; } } } exit; Could this somehow be adjusted to verify users, but not changing user passwords? The second possibility I see: all pppoe connections are logged in the mysql database. If I could somehow retrieve the username (or uid) of the user connected by pppoe, this could be used to authenticate users. Users could only check their internet connections and costs when they are online (and thus paying money), but this could be tolerated. Here's a line of the script that inserts connections into the database: my $username = $ENV{PEERNAME}; I thought it would be easy to use this variable, but $username seems to be always empty in test-scripts (print $username). Any idea how to retrieve the user connected to the pppoe server? Sorry for the long question! Any help would be very much appreciated. :)

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• Getting instance crashes on IntelliJ IDEA with scala plugin.

  - by egervari

  I am building a scala web project using scala test, lift, jpa, hibernate, mercurial plugin, etc. I am getting instant crashes, where the ide just bombs, the window shuts down, and it gives no error messages whatsoever when I am doing any amount of copy/pasting of code. This started happening once my project got to about 100 unit tests. This problem is incredibly annoying, because when the crash happens, 30-60 seconds of activity is not saved. Even IDEA will forget which files were last opened and will forget where the cursor was, which makes it really hard to continue where you left off after the crash. A lot can happen in 60 seconds! Now, I've given up, because it seems like all sorts of things cause the IntelliJ IDEA to crash over and over. For example, if I were to copy and paste this code, to write a similar test for another collection type, it would crash shortly after: it should "cascade save and delete status messages" in { val statusMessage = new StatusMessage("message") var user = userDao.find(1).get user.addToStatusMessages(statusMessage) userDao.save(user) statusMessage.isPersistent should be (true) userDao.delete(user) statusMessageDao.find(statusMessage.id) should equal (None) } There is nothing special about this piece of code. It's code that is working just fine. However, IDEA bombs shortly after I paste something like this. For example, I might change StatusMessage to the new class I want to test cascading on... and then have to import that class into the test... and BOOM... it crashed. On windows 7, the IDEA window literally just minimizes and crashes with no warning. The next time I startup IDEA, it has no memory of what happened. Now, I've had this problem before. I posted it way back on IDEA's YouTrack. I was told to invalidate my caches. That never fixed it then, and it's not fixing it now. Please help. This error is fairly random, but it's happening constantly now. I could program for hours and not see it before... and the fact that my work just gets destroyed and I can't remember what I did during the last minute causes me to swear at my monitor at a db level higher than my stereo can go.

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• Displaying unnecessary HTML when showing content from MySQL database.

  - by ThatMacLad

  My homepage pulls in content from my MySQL database to create a blog. I've got it so that it only displays an extract from the posts. For some reason it displays HTML tags as well rather than formatting it using the tags (See picture below). Any help is appreciated. Homepage: <html> <head> <title>Ultan Casey | Homepage</title> <link rel="stylesheet" href="css/style.css" type="text/css" /> </head> <body> <div class="wrapper"> <div id="upperbar"> <a href="#">Home</a> <a href="#">About Me</a> <a href="#">Contact Me</a> <a href="http://www.twitter.com/UltanKC">Twitter</a> <form id="search-form" action="/search" method="get"> <input type="text" id="textarea" size="33" name="q" value=""/> <input type="submit" id="submit" value="Search"/> </form> </div> <div id="banner"> <img src="images/banner.jpg"> </div> <div class="sidebar"></div> <div class="posts"> <?php mysql_connect ('localhost', 'root', 'root') ; mysql_select_db ('tmlblog'); $sql = "SELECT * FROM php_blog ORDER BY timestamp DESC LIMIT 5"; $result = mysql_query($sql) or print ("Can't select entries from table php_blog.<br />" . $sql . "<br />" . mysql_error()); while($row = mysql_fetch_array($result)) { $date = date("l F d Y", $row['timestamp']); $title = stripslashes($row['title']); $entry = stripslashes($row['entry']); $id = $row['id']; ?> <?php echo "<p id='title'><strong><a href=\"post.php?id=". $id . "\">" . $title . "</a></strong></p>"; ?><br /> <div class="post-thumb"><img src="thumbs/<?php echo $id ?>.png"></div> <?php echo htmlspecialchars(substr($entry, 0, 1050)) ?>... <br> <hr><br /> Posted on <?php echo $date; ?> </p> </div> </div> </p <?php } ?> </div> </div> </div> </body> </html> Image:

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• Updating with using custom class collection not working

  - by Risho

  I've posted this yesterday on asp forum but no one replied so perhaps I'll have better luck here. For some reason the OnUpdating method does not pull new values from the grid which is in edit mode. I've search and have come across several blogs and sites, some sugesting that an ObjectDataSource is required in order to use the "e.NewValue" construct others provide code to the contrary. I don't get any errors - the variables in the code file would contain the old values rather then new ones. I don't want to use the ODS way of manipulating the data. My delete method works but not the update one. Can you suggest what is wrong with the code? Here is what I've got: aspx file: <asp:GridView ID="gvBlack" runat="server" AutoGenerateColumns="False" OnRowUpdating="gvBlack_OnUpdating" OnRowEditing="gvBlack_RowEditing"> <Columns> <%--<asp:BoundField DataField="Ident_Black" ReadOnly="True" visible="false" />--%> <asp:TemplateField ItemStyle-Width="1px"> <EditItemTemplate> <asp:Label ID="lblIdent_Black" runat="server" Text='<%# Bind("Ident_Black") %>' Visible="false" /> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Model" > <ItemTemplate> <asp:Label ID="lblModel_Black" runat="server" Text='<%# Bind("Model_Black") %>' width="130px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtModel_Black" runat="server" Text='<%# Eval("Model_Black") %>' width="100px" /> <asp:RequiredFieldValidator ID="rfvModel_Black" runat="server" ControlToValidate="txtModel_Black" SetFocusOnError="true" ErrorMessage="*" ValidationGroup="CurrentMfg" ForeColor="Red" Font-Bold="true" /> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Description" > <ItemTemplate> <asp:Label ID="lblDesc_Black" runat="server" Text='<%# Bind("Desc_Black") %>' width="200px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtDesc_Black" runat="server" Text='<%# Eval("Desc_Black") %>' width="170px" /> <span></span> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Qty" > <ItemTemplate> <asp:Label ID="lblQty_Black" runat="server" Text='<%# Bind("Qty_Black") %>' width="35px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtQty_Black" runat="server" Text='<%# Eval("Qty_Black") %>' width="35px" /> <asp:RequiredFieldValidator ID="rfvQty_Black" runat="server" ControlToValidate="txtQty_Black" SetFocusOnError="true" ErrorMessage="*" ValidationGroup="CurrentMfg" ForeColor="Red" Font-Bold="true" /> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Reorder<br />Limit"> <ItemTemplate> <asp:Label ID="lblBlack_Reorder_Limit" runat="server" Text='<%# Bind("Black_Reorder_Limit") %>' width="35px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtBlack_Reorder_Limit" runat="server" Text='<%# Eval("Black_Reorder_Limit") %>' width="35px" /> <asp:RequiredFieldValidator ID="rfvBlack_Reorder_Limit" runat="server" ControlToValidate="txtBlack_Reorder_Limit" SetFocusOnError="true" ErrorMessage="*" ValidationGroup="CurrentMfg" ForeColor="Red" Font-Bold="true" /> </EditItemTemplate> </asp:TemplateField> <asp:TemplateField HeaderText="Notes"> <ItemTemplate> <asp:Label ID="lblNotes" runat="server" Text='<%# Bind("Notes") %>' width="200px" /> </ItemTemplate> <EditItemTemplate> <asp:TextBox ID="txtNotes" runat="server" Text='<%# Eval("Notes") %>' width="170px" /> <span></span> </EditItemTemplate> </asp:TemplateField> <asp:CommandField ShowEditButton="True" ShowDeleteButton="false" ValidationGroup="CurrentToner" /> </Columns> </asp:GridView> aspx.cs file: protected void Page_Load(object sender, EventArgs e) { LoadData_TonerBlack(); } private void LoadData_TonerBlack() { dalConsumables_TonerBlack drTonerBlack = new dalConsumables_TonerBlack(); gvBlack.DataSource = drTonerBlack.GetListTonersBlack(); gvBlack.DataBind(); } protected void gvBlack_OnUpdating(object sender, GridViewUpdateEventArgs e) { //GridView gvBlack = (GridView)sender; //GridViewRow gvBlackRow = (GridViewRow)gvBlack.Rows[e.RowIndex]; int _Ident_Black = Convert.ToInt32(gvBlack.DataKeys[e.RowIndex].Values[0].ToString()); TextBox _txtModel_Black = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtModel_Black"); TextBox _txtDesc_Black = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtDesc_Black"); TextBox _txtQty_Black = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtQty_Black"); TextBox _txtBlack_Reorder_Limit = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtBlack_Reorder_Limit"); TextBox _txtNotes = (TextBox)gvBlack.Rows[e.RowIndex].FindControl("txtNotes"); string _updatedBy = Request.ServerVariables["AUTH_USER"].ToString(); dalConsumables_TonerBlack updateTonerBlack = new dalConsumables_TonerBlack(); updateTonerBlack.UpdateTonerBlack(_Ident_Black, _txtModel_Black.Text, _txtDesc_Black.Text, Convert.ToInt32(_txtQty_Black.Text), Convert.ToInt32(_txtBlack_Reorder_Limit.Text), _txtNotes.Text, _updatedBy); gvBlack.EditIndex = -1; LoadData_TonerBlack(); } protected void gvBlack_RowEditing(object sender, GridViewEditEventArgs e) { gvBlack.EditIndex = e.NewEditIndex; LoadData_TonerBlack(); } Thanks in advance! Risho

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• Differences between matrix implementation in C

  - by tempy

  I created two 2D arrays (matrix) in C in two different ways. I don't understand the difference between the way they're represented in the memory, and the reason why I can't refer to them in the same way: scanf("%d", &intMatrix1[i][j]); //can't refer as &intMatrix1[(i * lines)+j]) scanf("%d", &intMatrix2[(i * lines)+j]); //can't refer as &intMatrix2[i][j]) What is the difference between the ways these two arrays are implemented and why do I have to refer to them differently? How do I refer to an element in each of the arrays in the same way (?????? in my printMatrix function)? int main() { int **intMatrix1; int *intMatrix2; int i, j, lines, columns; lines = 3; columns = 2; /************************* intMatrix1 ****************************/ intMatrix1 = (int **)malloc(lines * sizeof(int *)); for (i = 0; i < lines; ++i) intMatrix1[i] = (int *)malloc(columns * sizeof(int)); for (i = 0; i < lines; ++i) { for (j = 0; j < columns; ++j) { printf("Type a number for intMatrix1[%d][%d]\t", i, j); scanf("%d", &intMatrix1[i][j]); } } /************************* intMatrix2 ****************************/ intMatrix2 = (int *)malloc(lines * columns * sizeof(int)); for (i = 0; i < lines; ++i) { for (j = 0; j < columns; ++j) { printf("Type a number for intMatrix2[%d][%d]\t", i, j); scanf("%d", &intMatrix2[(i * lines)+j]); } } /************** printing intMatrix1 & intMatrix2 ****************/ printf("intMatrix1:\n\n"); printMatrix(*intMatrix1, lines, columns); printf("intMatrix2:\n\n"); printMatrix(intMatrix2, lines, columns); } /************************* printMatrix ****************************/ void printMatrix(int *ptArray, int h, int w) { int i, j; printf("Printing matrix...\n\n\n"); for (i = 0; i < h; ++i) for (j = 0; j < w; ++j) printf("array[%d][%d] ==============> %d\n, i, j, ??????); }

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• Multi-tier applications using L2S, WCF and Base Class

  - by Gena Verdel

  Hi all. One day I decided to build this nice multi-tier application using L2S and WCF. The simplified model is : DataBase-L2S-Wrapper(DTO)-Client Application. The communication between Client and Database is achieved by using Data Transfer Objects which contain entity objects as their properties. abstract public class BaseObject { public virtual IccSystem.iccObjectTypes ObjectICC_Type { get { return IccSystem.iccObjectTypes.unknownType; } } [global::System.Data.Linq.Mapping.ColumnAttribute(Storage = "_ID", AutoSync = AutoSync.OnInsert, DbType = "BigInt NOT NULL IDENTITY", IsPrimaryKey = true, IsDbGenerated = true)] [global::System.Runtime.Serialization.DataMemberAttribute(Order = 1)] public virtual long ID { //get; //set; get { return _ID; } set { _ID = value; } } } [DataContract] public class BaseObjectWrapper<T> where T : BaseObject { #region Fields private T _DBObject; #endregion #region Properties [DataMember] public T Entity { get { return _DBObject; } set { _DBObject = value; } } #endregion } Pretty simple, isn't it?. Here's the catch. Each one of the mapped classes contains ID property itself so I decided to override it like this [global::System.Data.Linq.Mapping.TableAttribute(Name="dbo.Divisions")] [global::System.Runtime.Serialization.DataContractAttribute()] public partial class Division : INotifyPropertyChanging, INotifyPropertyChanged { [global::System.Data.Linq.Mapping.ColumnAttribute(Storage="_ID", AutoSync=AutoSync.OnInsert, DbType="BigInt NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)] [global::System.Runtime.Serialization.DataMemberAttribute(Order=1)] public override long ID { get { return this._ID; } set { if ((this._ID != value)) { this.OnIDChanging(value); this.SendPropertyChanging(); this._ID = value; this.SendPropertyChanged("ID"); this.OnIDChanged(); } } } } Wrapper for division is pretty straightforward as well: public class DivisionWrapper : BaseObjectWrapper<Division> { } It worked pretty well as long as I kept ID values at mapped class and its BaseObject class the same(that's not very good approach, I know, but still) but then this happened: private CentralDC _dc; public bool UpdateDivision(ref DivisionWrapper division) { DivisionWrapper tempWrapper = division; if (division.Entity == null) { return false; } try { Table<Division> table = _dc.Divisions; var q = table.Where(o => o.ID == tempWrapper.Entity.ID); if (q.Count() == 0) { division.Entity._errorMessage = "Unable to locate entity with id " + division.Entity.ID.ToString(); return false; } var realEntity = q.First(); realEntity = division.Entity; _dc.SubmitChanges(); return true; } catch (Exception ex) { division.Entity._errorMessage = ex.Message; return false; } } When trying to enumerate over the in-memory query the following exception occurred: Class member BaseObject.ID is unmapped. Although I'm stating the type and overriding the ID property L2S fails to work. Any suggestions?

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• How do I create a thread-safe write-once read-many value in Java?

  - by Software Monkey

  This is a problem I encounter frequently in working with more complex systems and which I have never figured out a good way to solve. It usually involves variations on the theme of a shared object whose construction and initialization are necessarily two distinct steps. This is generally because of architectural requirements, similar to applets, so answers that suggest I consolidate construction and initialization are not useful. By way of example, let's say I have a class that is structured to fit into an application framework like so: public class MyClass { private /*ideally-final*/ SomeObject someObject; MyClass() { someObject=null; } public void startup() { someObject=new SomeObject(...arguments from environment which are not available until startup is called...); } public void shutdown() { someObject=null; // this is not necessary, I am just expressing the intended scope of someObject explicitly } } I can't make someObject final since it can't be set until startup() is invoked. But I would really like it to reflect it's write-once semantics and be able to directly access it from multiple threads, preferably avoiding synchronization. The idea being to express and enforce a degree of finalness, I conjecture that I could create a generic container, like so: public class WoRmObject<T> { private T object; WoRmObject() { object=null; } public WoRmObject set(T val) { object=val; return this; } public T get() { return object; } } and then in MyClass, above, do: private final WoRmObject<SomeObject> someObject; MyClass() { someObject=new WoRmObject<SomeObject>(); } public void startup() { someObject.set(SomeObject(...arguments from environment which are not available until startup is called...)); } Which raises some questions for me: Is there a better way, or existing Java object (would have to be available in Java 4)? Is this thread-safe provided that no other thread accesses someObject.get() until after it's set() has been called. The other threads will only invoke methods on MyClass between startup() and shutdown() - the framework guarantees this. Given the completely unsynchronized WoRmObject container, it is ever possible under either JMM to see a value of object which is neither null nor a reference to a SomeObject? In other words, does has the JMM always guaranteed that no thread can observe the memory of an object to be whatever values happened to be on the heap when the object was allocated.

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• How to allow multiple filters to be selected - pagination?

  - by NewSOuser

  Hey, I am still trying to allow multiple filters to be selected for my pagination script but not sure how to do it being very new to php and programing in general. So in my pagination, when a user clicks the 'marketing' button(link) it queries the database just for the category that = marketing. The same goes for the other 2 filter buttons as seen in the script below. (automotive, sports). The problem is, I want to be able to select multiple filters like only marketing and auomotive or automotive and sports, for example if I click the marketing filter and then the automotive, it would display the categories that equal marketing, and automotive. I have no idea how to accomplish this, so I have come to the experts to help me out. This is the script I am working on: <h3>Filter results by:</h3> <a href='pagi_test.php?category=marketing'>marketing</a> <a href='pagi_test.php?category=automotive'>automotive</a> <a href='pagi_test.php?category=sports'>sports</a> <br /> <h3>Results:</h3> <?php //connecting to the database $error = "Could not connect to the database"; mysql_connect('localhost','root','root') or die($error); mysql_select_db('ajax_demo') or die($error); //max displayed per page $per_page = 3; //get start variable $start = $_GET['start']; $category = mysql_real_escape_string($_GET['category']); //count records $record_count = mysql_num_rows(mysql_query("SELECT * FROM explore WHERE category='$category'")); //count max pages $max_pages = $record_count / $per_page; //may come out as decimal if (!$start) $start = 0; //display data $get = mysql_query("SELECT * FROM explore WHERE category='$category' LIMIT $start, $per_page"); ?> <table width="800px"> <?php while ($row = mysql_fetch_assoc($get)) { // get data $id = $row['id']; $site_name = $row['site_name']; $site_description = $row['site_description']; ?> <tr> <td><?php echo $id; ?></td> <td><?php echo $site_name; ?></td> <td><?php echo $site_description; ?></td> </tr> <?php } //setup prev and next variables $prev = $start - $per_page; $next = $start + $per_page; //show prev button if (!($start<=0)) echo "<a href='pagi_test.php?category=$category&start=$prev'>Prev</a> "; //show page numbers //set variable for first page $i=1; for ($x=0;$x<$record_count;$x=$x+$per_page) { if ($start!=$x) echo " <a href='pagi_test.php?category=$category&start=$x'>$i</a> "; else echo " <a href='pagi_test.php?category=$category&start=$x'><b>$i</b></a> "; $i++; } //show next button if (!($start>=$record_count-$per_page)) echo " <a href='pagi_test.php?category=$category&start=$next'>Next</a>"; ?> Any help on this would be great. Thank you. -- EDIT -- If anyone has a better method of doing a pagination system with multiple filters than the one above, please let me know.

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