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• Help, my CentOS servers keep going down , No route to host after a random uptime [closed]

  - by user249071

  Hello , I have a couple of Centos linux servers, that have a very simple task, they run nginx + fastcgi for php , and some NFS mounts between them, readonly They have some RPC commands to start some downloading processes with wget, nothing fancy , from a main server, but their behavior is very unstable, they simply go down, we tried to monitor ram , processor usage, even network connections, they don't load up so much, max network connections up to... 250 max, 15% processor usage and memory , well, doesn't even fill up, 2.5GB from 8GB max , I have no ideea why can a linux server go down like that, they aren't even public servers, no domain names installed no public serving, for sites. The only thing that I've discovered was that if i didn't restart the network service every couple of hours or so... the servers were becoming very slow, starting apps very slow, but not repoting a high usage of resources...Maybe Centos doesn't free the timeout connections, or something like that...It's based on Red Hat right? I'm not a linux expert , but I'm sure that there are a few guys out there that can easily have an answer to this , or even have some leads to what i can do ... I haven't installed snort, or other things to view if we have some DOS attacks, still the scheduled script that restarts the network each hour should put the system back online, and it doesn't.... Thank you in advance

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• What is the header of an array in .NET

  - by Thomas

  Hi all, I have a little bit seen the representation of an array in memory with Windbg and SOS plugin. Here it is the c# : class myobj{ public int[] arr; } class Program{ static void Main(string[] args){ myobj o = new myobj(); o.arr = new int[7]; o.arr[0] = 0xFFFFFF; o.arr[1] = 0xFFFFFF; o.arr[2] = 0xFFFFFF; o.arr[3] = 0xFFFFFF; o.arr[4] = 0xFFFFFF; } } I break at final of Main, and I observ : 0:000> !clrstack -l OS Thread Id: 0xc3c (0) ESP EIP 0015f0cc 0043d1cf test.Program.Main(System.String[]) LOCALS: 0x0015f0d8 = 0x018a2f58 0:000 !do 0x018a2f58 Name: test.myobj MethodTable: 0026309c EEClass: 00261380 Size: 12(0xc) bytes (C:\Users\admin\Documents\Visual Studio 2008\Projects\test\test\bin\Debug\test.exe) Fields: MT Field Offset Type VT Attr Value Name 01324530 4000001 4 System.Int32[] 0 instance 018a2f64 tab 0:000 dd 018a2f64 018a2f64 01324530 00000007 00ffffff 00ffffff 018a2f74 00ffffff 00ffffff 00ffffff 00000000 018a2f84 00000000 00000000 00000000 00000000 018a2f94 00000000 00000000 00000000 00000000 018a2fa4 00000000 00000000 00000000 00000000 018a2fb4 00000000 00000000 00000000 00000000 018a2fc4 00000000 00000000 00000000 00000000 018a2fd4 00000000 00000000 00000000 00000000 I can see that the header contains the size of the array (00000007) but my question is : what is the value 01324530 ? Thanks !

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• Reasons for & against a Database

  - by dbemerlin

  Hi, i had a discussion with a coworker about the architecture of a program i'm writing and i'd like some more opinions. The Situation: The Program should update at near-realtime (+/- 1 Minute). It involves the movement of objects on a coordinate system. There are some events that occur at regular intervals (i.e. creation of the objects). Movements can change at any time through user input. My solution was: Build a server that runs continously and stores the data internally. The server dumps a state-of-the-program at regular intervals to protect against powerfailures and/or crashes. He argued that the program requires a Database and i should use cronjobs to update the data. I can store movement information by storing startpoint, endpoint and speed and update the position in the cronjob (and calculate collisions with other objects there) by calculating direction and speed. His reasons: Requires more CPU & Memory because it runs constantly. Powerfailures/Crashes might destroy data. Databases are faster. My reasons against this are mostly: Not very precise as events can only occur at full minutes (wouldn't be that bad though). Requires (possibly costly) transformation of data on every run from relational data to objects. RDBMS are a general solution for a specialized problem so a specialized solution should be more efficient. Powerfailures (or other crashes) can leave the Data in an undefined state with only partially updated data unless (possibly costly) precautions (like transactions) are taken. What are your opinions about that? Which arguments can you add for any side?

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• working with large sprite sheets on iphone

  - by lukya

  Hi All, I am trying to use sprite sheet animation in my application. The first POC with a small sprite sheet worked fine but as i change the sprite sheet to a bigger one, i get "check_safe_call: could not restore current frame" warning and the application quits. A quick search revealed that this problem meant my app is taking too much memory or the image is too huge in dimension. My image is 4.9 Mb and dimensions are 6720 * 10080 (oops!!). i read that iphone allows maximum 3 Mb image with dimensions up to 1024 * 1024. Also that the sprite sheet image dimensions should be a power of two. So please let me know how i can use a sprite sheet this big. One approach could be to cut the sprite sheet into many smaller sprite sheets and use them one at a time. Please suggest if you know any other/better approach to accommodate bigger sprite sheets and whether the problem with my sprite sheet is size (4.9 Mb) OR dimensions (6720 * 10080). (Just FYI, i am not trying to play a movie so using MP4 file instead is not an option for me. i need to animate the sprite sheet based on accelerometer input and i have been able to achieve that in my POC with smaller sprite sheet.) Thanks, Swapnil

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• Objective-C autorelease pool not releasing object

  - by Chris

  Hi I am very new to Objective-C and was reading through memory management. I was trying to play around a bit with the NSAutoreleasePool but somehow it wont release my object. I have a class with a setter and getter which basically sets a NSString *name. After releasing the pool I tried to NSLog the object and it still works but I guess it should not? @interface TestClass : NSObject { NSString *name; } - (void) setName: (NSString *) string; - (NSString *) name; @end @implementation TestClass - (void) setName: (NSString *) string { name = string; } - (NSString *) name { return name; } @end int main (int argc, const char * argv[]) { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; TestClass *var = [[TestClass alloc] init]; [var setName:@"Chris"]; [var autorelease]; [pool release]; // This should not be possible? NSLog(@"%@",[var name]); return 0; }

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• XMLStreamReader and a real stream

  - by Yuri Ushakov

  Update There is no ready XML parser in Java community which can do NIO and XML parsing. This is the closest I found, and it's incomplete: http://wiki.fasterxml.com/AaltoHome I have the following code: InputStream input = ...; XMLInputFactory xmlInputFactory = XMLInputFactory.newInstance(); XMLStreamReader streamReader = xmlInputFactory.createXMLStreamReader(input, "UTF-8"); Question is, why does the method #createXMLStreamReader() expects to have an entire XML document in the input stream? Why is it called a "stream reader", if it can't seem to process a portion of XML data? For example, if I feed: <root> <child> to it, it would tell me I'm missing the closing tags. Even before I begin iterating the stream reader itself. I suspect that I just don't know how to use a XMLStreamReader properly. I should be able to supply it with data by pieces, right? I need it because I'm processing a XML stream coming in from network socket, and don't want to load the whole source text into memory. Thank you for help, Yuri.

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• Collecting high-volume video viewing data

  - by DanK

  I want to add tracking to our Flash-based media player so that we can provide analytics that show what sections of videos are being watched (at the moment, we just register a view when a video starts playing) For example, if a viewer watches the first 30 seconds of a video and then clicks away to something else, we want the data to reflect that. Likewise, if someone watches the first 10 seconds, then scrubs the timeline to the last minute of the video and watches that, we want to register viewing on the parts watched and not the middle section. My first thought was to collect up the viewing data in the player and send it all to the server at the end of a viewing session. Unfortunately, Flash does not seem to have an event that you can hook into when a viewer clicks away from the page the movie is on (probably a good thing - it would be open to abuse) So, it looks like we're going to have to make regular requests to the server as the video is playing. This is obviously going to lead to a high volume of requests when there are large numbers of simultaneous viewers. The simple approach of dumping all these 'heartbeat' events from clients to a database feels like it will quickly become unmanageable so I'm wondering whether I should be taking an approach where viewing sessions are cached in memory and flushed to database when they become inactive (based on a timeout). That way, the data could be stored as time spans rather than individual heartbeats. So, to the question - what is the best way to approach dealing with this kind of high-volume viewing data? Are there any good existing architectures/patterns? Thanks, Dan.

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• ASP.NET MVC Paging for a search form

  - by James Alexander

  I've read several different posts on paging w/ in MVC but none describe a scenario where I have something like a search form and then want to display the results of the search criteria (with paging) beneath the form once the user clicks submit. My problem is that, the paging solution I'm using will create <a href="..."> links that will pass the desired page like so: http://mysite.com/search/2/ and while that's all fine and dandy, I don't have the results of the query being sent to the db in memory or anything so I need to query the DB again. If the results are handled by the POST controller action for /Search and the first page of the data is rendered as such, how do I get the same results (based on the form criteria specified by the user) when the user clicks to move to page 2? Some javascript voodoo? Leverage Session State? Make my GET controller action have the same variables expected by the search criteria (but optional), when the GET action is called, instantiate a FormCollection instance, populate it and pass it to the POST action method (there-by satisfying DRY)? Can someone point me in the right direction for this scenario or provide examples that have been implemented in the past? Thanks!

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• Optimizing MySQL for ALTER TABLE of InnoDB

  - by schuilr

  Sometime soon we will need to make schema changes to our production database. We need to minimize downtime for this effort, however, the ALTER TABLE statements are going to run for quite a while. Our largest tables have 150 million records, largest table file is 50G. All tables are InnoDB, and it was set up as one big data file (instead of a file-per-table). We're running MySQL 5.0.46 on an 8 core machine, 16G memory and a RAID10 config. I have some experience with MySQL tuning, but this usually focusses on reads or writes from multiple clients. There is lots of info to be found on the Internet on this subject, however, there seems to be very little information available on best practices for (temporarily) tuning your MySQL server to speed up ALTER TABLE on InnoDB tables, or for INSERT INTO .. SELECT FROM (we will probably use this instead of ALTER TABLE to have some more opportunities to speed things up a bit). The schema changes we are planning to do is adding a integer column to all tables and make it the primary key, instead of the current primary key. We need to keep the 'old' column as well so overwriting the existing values is not an option. What would be the ideal settings to get this task done as quick as possible?

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• PHPUnit reporting "Aborted" no matter what tests are run

  - by GrumpyCanuck

  Having a weird problem with PHPUnit. We're using PHPUnit as part of a continuous integration environment, that contains one app written using Zend Framework and one app written using CodeIgniter. Unit tests run just fine under Zend Framework, but whenever I run the tests for CodeIgniter using fooStack's CIUnit bridge, I always get the same problem at the end: PHPUnit 3.4.14 by Sebastian Bergmann. ............... . Time: 1 second, Memory: 7.00Mb OK (16 tests, 14 assertions) Aborted First off, I do not know what those empty spaces between the . means. Secondly, no matter what test I run (all of them or each one separately) I get the same Aborted message at the very end. The tests themselves do not contain any exit or die statements. When I run the same version of PHPUnit on my laptop (running OS-X Snow Leopard and same version of Zend Server Community Edition) I do not get that aborted message. Running PHP 5.3.2 on Ubuntu installed using Zend Server Community Edition. Any help with this would be greatly appreciated.

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• Putting BigDecimal data into HSQLDB test database using DbUnit

  - by Denise

  Hi everyone, I'm using Hibernate JPA in my backend. I am writing a unit test using JUnit and DBUnit to insert a set of data into an in-memory HSQL database. My dataset contains: <order_line order_line_id="1" quantity="2" discount_price="0.3"/> Which maps to an OrderLine Java object where the discount_price column is defined as: @Column(name = "discount_price", precision = 12, scale = 2) private BigDecimal discountPrice; However, when I run my test case and assert that the discount price returned equals 0.3, the assertion fails and says that the stored value is 0. If I change the discount_price in the dataset to be 0.9, it rounds up to 1. I've checked to make sure HSQLDB isn't doing the rounding and it definitely isn't because I can insert an order line object using Java code with a value like 5.3 and it works fine. To me, it seems like DBUtils is for some reason rounding the number I've defined. Is there a way I can force this to not happen? Can anyone explain why it might be doing this? Thanks!

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• NHibernate IQueryable Collection as Property of Root

  - by Khalid Abuhakmeh

  Hello and thank you for taking the time to read this. I have a root object that has a property that is a collection. For example : I have a Shelf object that has Books. // now public class Shelf { public ICollection<Book> Books {get; set;} } // want public class Shelf { public IQueryable<Book> Books {get;set;} } What I want to accomplish is to return a collection that is IQueryable so that I can run paging and filtering off of the collection directly from the the parent. var shelf = shelfRepository.Get(1); var filtered = from book in shelf.Books where book.Name == "The Great Gatsby" select book; I want to have that query executed specifically by NHibernate and not a get all to load a whole collection and then parse it in memory (which is what currently happens when I use ICollection). The reasoning behind this is that my collection could be huge, tens of thousands of records, and a get all query could bash my database. I would like to do this implicitly so that when NHibernate sees and IQueryable on my class it knows what to do. I have looked at NHibernates Linq provider and currently I am making the decision to take large collections and split them into their own repository so that I can make explicit calls for filtering and paging. Linq To SQL offers something similar to what I'm talking about.

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• ASP.NET application - Error when trying to connect to a SQL Server 2008 instance

  - by Pablo Dami

  Hi everyone! Despite that I’m a regular reader of this great forum, this is my first post on it. I believe that this community can help me with the following problem that I have. I’m trying to publish an ASP.NET website over an IIS 6.0 (Windows 2003 Server), and I have some troubles trying to connect to the database. Curiously, I have installed another ASP.NET website into the same IIS 6.0 with the same properties and security parameters and can connect without problems with the same database. The application that works fine is almost the same that the one that can’t connect with SQL Server (actually is the same but with several modifications). I’ll enumarate some information related to the problem: S.O: Windows 2003 Server SQL Server Engine: SQL Server 2008 SQL Server accept remote connections? Yes. ASP.NET version: 2.0.50727 The connections via TCP/IP are enabled to the SQL Server instance? Yes. The corresponding user that I have in the connection string, actually exists into the database with the “owner” role? Yes. ORM Tool used: nHibernate I get the following error when I try to run the aplication into the browser: Error while establishing a connection to the server. When connecting to SQL Server 2005, this failure may occur because the default settings SQL Server does not allow remote connections. (provider: Shared Memory Provider, error: 40 - Could not open a connection to SQL Server) In order to isolate the problem, I made some test. For example, using the web app that works fine I can connect without any problema with the database that uses the web app that can’t. With this evidence I concluded that the problem is within the web app and not into the SQL Server instance. I also google it my problem but sadly I can't find nothing usefull to solve it. If someone can help me I’ll appreciate that. Thank you so much for your time!

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• How to enforce foreign keys using Xerial SQLite JDBC?

  - by Space_C0wb0y

  According to their release notes, the Xerial SQLite JDBC driver supports foreign keys since version 3.6.20.1. I have tried some time now to get a foreign key constraint to be enforced, but to no avail. Here is what I came up with: public static void main(String[] args) throws ClassNotFoundException, SQLException { Class.forName("org.sqlite.JDBC"); SQLiteConfig config = new SQLiteConfig(); config.enforceForeignKeys(true); Connection connection = DriverManager.getConnection("jdbc:sqlite::memory:", config.toProperties()); connection.createStatement().executeUpdate( "CREATE TABLE artist(" + "artistid INTEGER PRIMARY KEY, " + "artistname TEXT);"); connection.createStatement().executeUpdate( "CREATE TABLE track("+ "trackid INTEGER," + "trackname TEXT," + "trackartist INTEGER," + "FOREIGN KEY(trackartist) REFERENCES artist(artistid)" + ");"); connection.createStatement().executeUpdate( "INSERT INTO track VALUES(14, 'Mr. Bojangles', 3)"); } The table definitions are taken directly from the sample in the SQLite documentation. This is supposed to fail, but it doesn't. I also checked, and it really inserts the tuple (no ignore or something like that). Does anyone have any experience with that, or knows how to make it work?

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• Run a PHP script every second using CLI

  - by Saif Bechan

  Hello, I have a dedicated server running Cent OS with a Parallel PLESK panel. I need to run a php script every second, that updates my database. These is no alternative way timewise, i have checked every method, it needs to be updated every second. I can find my script using the url: http://www.mysite.com/phpfile.php?key=123, and this has to be executed every second. Does anyone have any knowledge at all on doing this, i can not seem to find the answer. I heard about doing it with CLI and putty, but i have no knowledge of this at all. Or can this be done using the PLESK Panel? And can the file be executed locally every second. Like \phpfile.php If someone helps me on answering these question i would really appreciate it. Regards EDIT It has been a few months since i added this question. I ended up using the following code: #!/user/bin/php $start = microtime(true); set_time_limit(60); for (i = 0; i < 59; ++$i) { doMyThings(); time_sleep_until($start + $i + 1); } Thank you for this code guys! My cronjob is set to every minute. I have been running this for some time now in a test environment, and this works out great. It works really supperfast, and i see no increase in CPU nor Memory usage.

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• Maintaining a pool of DAO Class instances vs doing new operator

  - by Fazal

  we have been trying to benchmark our application performance in multiple way for sometime now. I always believed that object creation in java using Class.newInstance() was not slow (at least after 1.4 version of java). But we anyways did a test to use newInstance method vs mainitain an object pool of 1000 objects. We did about 200K iterations of loading data from DB using JDBC and populating these objects. I was amazed (even shocked) to see that newInstance code compared to object pool code was almost 10 times slower. These objects represent tables with about 50 fields and all string type. Can someone share there thoughts on this issue as now I am more confused if object pooling of atleast some DAO instances is a better option. The pool size as I see right now should be large enough to meet size of average requests. There is a flip side as my memory footprint will go up but I am beginning to wonder if this kind of idea makes sense atleast for some of the DAO entities representing tables of about 50 or more columns Please share your ideas and let me know if this has been tried by someone or am I missing some point here

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• C pointers and addresses

  - by yCalleecharan

  Hi, I always thought that *&p = p = &*p in C. I tried this code: #include <stdio.h> #include <stdlib.h> char a[] = "programming"; char *ap = &a[4]; int main(void) { printf("%x %x %x\n", ap, &*(ap), *&(ap)); /* line 13 */ printf("%x %x %x\n\n", ap+1, &*(ap+1), *&(ap+1)); /* line 14 */ } The first printf line (line 13) gives me the addresses: 40b0a8 40b0a8 40b0a8 which are the same as expected. But when I added the second printf line, Borland complains: "first.c": E2027 Must take address of a memory location in function main at line 14 I was expecting to get: 40b0a9 40b0a9 40b0a9. It seems that the expression *&(ap+1) on line 14 is the culprit here. I thought all three pointer expressions on line 14 are equivalent. Why am I thinking wrong? A second related question: The line char *ap = a; points to the first element of array a. I used char *ap = &a[4]; to point to the 5th element of array a. Is the expression char *ap = a; same as the expression char *ap = &a[0]; Is the last expression only more verbose than the previous one? Thanks a lot...

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• use startActivityForResult from non-activity

  - by rayman

  Hi, I have MainActivity which is an Activity and other class(which is a simple java class), we`ll call it "SimpleClass". now i want to run from that class the command startActivityForResult. now i though that i could pass that class(SimpleClass), only MainActivity's context, problem is that, u cant run context.startActivityForResult(...); so the only way making SimpleClass to use 'startActivityForResult; is to pass the reference of MainActivity as an Activity variable to the SimpleClass something like that: inside the MainActivity class i create the instance of SimpleClass this way: SimpleClass simpleClass=new SimpleClass(MainActivity.this); now this is how SimpleClass looks like: public Class SimpleClass { Activity myMainActivity; public SimpleClass(Activity mainActivity) { super(); this.myMainActivity=mainActivity; } .... } public void someMethod(...) { myMainActivity.startActivityForResult(...); } now its working, but isnt a proper way of doing this? I`am afraid i could have some memory leaks in the future. thanks. ray.

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• Database Functional Programming in Clojure

  - by Ralph

  "It is tempting, if the only tool you have is a hammer, to treat everything as if it were a nail." - Abraham Maslow I need to write a tool to dump a large hierarchical (SQL) database to XML. The hierarchy consists of a Person table with subsidiary Address, Phone, etc. tables. I have to dump thousands of rows, so I would like to do so incrementally and not keep the whole XML file in memory. I would like to isolate non-pure function code to a small portion of the application. I am thinking that this might be a good opportunity to explore FP and concurrency in Clojure. I can also show the benefits of immutable data and multi-core utilization to my skeptical co-workers. I'm not sure how the overall architecture of the application should be. I am thinking that I can use an impure function to retrieve the database rows and return a lazy sequence that can then be processed by a pure function that returns an XML fragment. For each Person row, I can create a Future and have several processed in parallel (the output order does not matter). As each Person is processed, the task will retrieve the appropriate rows from the Address, Phone, etc. tables and generate the nested XML. I can use a a generic function to process most of the tables, relying on database meta-data to get the column information, with special functions for the few tables that need custom processing. These functions could be listed in a map(table name -> function). Am I going about this in the right way? I can easily fall back to doing it in OO using Java, but that would be no fun. BTW, are there any good books on FP patterns or architecture? I have several good books on Clojure, Scala, and F#, but although each covers the language well, none look at the "big picture" of function programming design.

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• NSArray/NSMutableArray : Passed by ref or by value???

  - by wgpubs

  Totally confused here. I have a PARENT UIViewController that needs to pass an NSMutableArray to a CHILD UIViewController. I'm expecting it to be passed by reference so that changes made in the CHILD will be reflected in the PARENT and vice-versa. But that is not the case. Both have a property declared as .. @property (nonatomic, retain) NSMutableArray *photos; Example: In PARENT: self.photos = [[NSMutableArray alloc] init]; ChildViewController *c = [[ChildViewController alloc] init ...]; c.photos = self.photos; ... ... ... In CHILD: [self.photos addObject:obj1]; [self.photos addObject:obj2]; NSLog(@"Count:%d", [self.photos count]) // Equals 2 as expected ... Back in PARENT: NSLog(@"Count:%d", [self.photos count]) // Equals 0 ... NOT EXPECTED I thought they'd both be accessing the same memory. Is this not the case? If it isn't ... how do I keep the two NSMutableArrays in sync?

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• Total Order between !different! volatile variables?

  - by andreas

  Hi all, Consider the following Java code: volatile boolean v1 = false; volatile boolean v2 = false; //Thread A v1 = true; if (v2) System.out.println("v2 was true"); //Thread B v2 = true; if (v1) System.out.println("v1 was true"); If there was a globally visible total order for volatile accesses then at least one println would always be reached. Is that actually guaranteed by the Java Standard? Or is an execution like this possible: A: v1 = true; B: v2 = true; A: read v2 = false; B: read v1 = false; A: v2 = true becomes visible (after the if) B: v1 = true becomes visible (after the if) I could only find statements about accesses to the same volatile variable in the Standard (but I might be missing something). "A write to a volatile variable (§8.3.1.4) v synchronizes-with all subsequent reads of v by any thread (where subsequent is defined according to the synchronization order)." http://java.sun.com/docs/books/jls/third_edition/html/memory.html#17.4.4 Thanks!

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• Convert asp.net webforms logic to asp.net MVC

  - by gmcalab

  I had this code in an old asp.net webforms app to take a MemoryStream and pass it as the Response showing a PDF as the response. I am now working with an asp.net MVC application and looking to do this this same thing, but how should I go about showing the MemoryStream as PDF using MVC? Here's my asp.net webforms code: private void ShowPDF(MemoryStream ms) { try { //get byte array of pdf in memory byte[] fileArray = ms.ToArray(); //send file to the user Page.Response.Cache.SetCacheability(HttpCacheability.NoCache); Page.Response.Buffer = true; Response.Clear(); Response.ClearContent(); Response.ClearHeaders(); Response.Charset = string.Empty; Response.ContentType = "application/pdf"; Response.AddHeader("content-length", fileArray.Length.ToString()); Response.AddHeader("Content-Disposition", "attachment;filename=TID.pdf;"); Response.BinaryWrite(fileArray); Response.Flush(); Response.Close(); } catch { // and boom goes the dynamite... } }

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• error detection/correction/recovery in serial protocols

  - by Jason S

  I have some designing to do for a serial protocol and am running into some questions that I figure must have been considered elsewhere. So I'm wondering if there are some recommendations for best practices in designing serial protocols. (Please either state a fact that is easily verifiable, or cite a reputable source if you make a claim.) General recommendations for websites/books are also welcome. In particular I have to deal with issues like parsing a stream of bytes into packets verifying a packet is correct (easy with a CRC, for instance) identifying reasonable types of errors that can occur (e.g. in a point-to-point serial stream, sporadic single bit errors, and dropped series of bytes, are both likely, but extra phantom bytes are unlikely; whereas with a record stored in flash memory or on a disk drive the types of errors that predominate are different) error correction or recovery (if I detect an error in a packet, can I correct it? If not, can I resync to the boundary of the next packet?) how to make variable-length packets robust to error correction / recovery. Any suggestions?

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• Anonymous union definition/declaration in a macro GNU vs VS2008

  - by Alan_m

  I am attempting to alter an IAR specific header file for a lpc2138 so it can compile with Visual Studio 2008 (to enable compatible unit testing). My problem involves converting register definitions to be hardware independent (not at a memory address) The "IAR-safe macro" is: #define __IO_REG32_BIT(NAME, ADDRESS, ATTRIBUTE, BIT_STRUCT) \ volatile __no_init ATTRIBUTE union \ { \ unsigned long NAME; \ BIT_STRUCT NAME ## _bit; \ } @ ADDRESS //declaration //(where __gpio0_bits is a structure that names //each of the 32 bits as P0_0, P0_1, etc) __IO_REG32_BIT(IO0PIN,0xE0028000,__READ_WRITE,__gpio0_bits); //usage IO0PIN = 0x0xAA55AA55; IO0PIN_bit.P0_5 = 0; This is my comparable "hardware independent" code: #define __IO_REG32_BIT(NAME, BIT_STRUCT)\ volatile union \ { \ unsigned long NAME; \ BIT_STRUCT NAME##_bit; \ } NAME; //declaration __IO_REG32_BIT(IO0PIN,__gpio0_bits); //usage IO0PIN.IO0PIN = 0xAA55AA55; IO0PIN.IO0PIN_bit.P0_5 = 1; This compiles and works but quite obviously my "hardware independent" usage does not match the "IAR-safe" usage. How do I alter my macro so I can use IO0PIN the same way I do in IAR? I feel this is a simple anonymous union matter but multiple attempts and variants have proven unsuccessful. Maybe the IAR GNU compiler supports anonymous unions and vs2008 does not. Thank you.

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• How to delete a QProcess instance correctly?

  - by Kopfschmerzen

  Hi everyone! I have a class looking like this: class FakeRunner : public QObject { Q_OBJECT private: QProcess* proc; public: FakeRunner(); int run() { if (proc) return -1; proc = new QProcess(); QStringList args; QString programName = "fake.exe"; connect(comp, SIGNAL(started()), this, SLOT(procStarted())); connect(comp, SIGNAL(error(QProcess::ProcessError)), this, SLOT(procError(QProcess::ProcessError))); connect(comp, SIGNAL(finished(int, QProcess::ExitStatus)), this, SLOT(procFinished(int, QProcess::ExitStatus))); proc->start(programName, args); return 0; }; private slots: void procStarted() {}; void procFinished(int, QProcess::ExitStatus) {}; void procError(QProcess::ProcessError); } Since "fake.exe" does not exist on my system, proc emits the error() signal. If I handle it like following, my program crashes: void FakeRunner::procError(QProcess::ProcessError rc) { delete proc; proc = 0; } It works well, though, if I don't delete the pointer. So, the question is how (and when) should I delete the pointer to QProcess? I believe I have to delete it to avoid a memory leak. FakeRunner::run() can be invoked many times, so the leak, if there is one, will grow. Thanks!

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