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• Updating multiple related tables in SQLite

  - by PerryJ

  Just some background, sorry so long winded. I'm using the System.Data.SQLite ADO.net adapter to create a local sqlite database and this will be the only process hitting the database, so I don't need to worry about concurrency. I'm building the database from various sources and don't want to build this all in memory using datasets or dataadapters or anything like that. I want to do this using SQL (DdCommands). I'm not very good with SQL and complete noob in sqlite. I'm basically using sqlite as a local database / save file structure. The database has a lot of related tables and the data has nothing to do with People or Regions or Districts, but to use a simple analogy, imagine: Region table with auto increment RegionID, RegionName column and various optional columns. District table with auto increment DistrictID, DistrictName, RegionId, and various optional columns Person table with auto increment PersonID, PersonName, DistrictID, and various optional columns So I get some data representing RegionName, DistrictName,PersonName, and other Person related data. The Region, District and/or Person may or may not be created at this point. Once again, not being the greatest with this, my thoughts would be something like: Check to see if Region exists and if so get the RegionID else create it and get RegionID Check to see if District exists and if so get the DistrictID else create it adding in RegionID from above and get DistrictID Check to see if Person exists and if so get the PersonID else create it adding in DistrictID from above and get PersonID Update Person with rest of data. In MS SQL Server I would create a stored procedure to handle all this. Only way I can see to do this with sqlite is a lot of commands. So I'm sure I'm not getting this. I've spent hours looking around on various sites but just don't feel like I'm going down the right road. Any suggestions would be greatly appreciated.

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• Getting a binary file from resource in C#

  - by Jesse Knott

  Hello, I am having a bit of a problem, I am trying to get a PDF as a resource in my application. At this point I have a fillable PDF that I have been able to store as a file next to the binary, but now I am trying to embed the PDF as a resource in the binary. byte[] buffer; try { s = typeof(BattleTracker).Assembly.GetManifestResourceStream("libReports.Resources.DAForm1594.pdf"); buffer = new byte[s.Length]; int read = 0; do { read = s.Read(buffer, read, 32768); } while (read > 0); } catch (Exception e) { throw new Exception("Error: could not import report:", e); } // read existing PDF document PdfReader r = new PdfReader( // optimize memory usage buffer, null ); Every time I run the code I get an error saying "Rebuild trailer not found. Original Error: PDF startxref not found" When I was just opening the file via a path to the static file in my directory it worked fine. I have tried using different encodings UTF-8, UTF-32, UTF-7, ASCII, etc etc.... As a side note I had the same problem with getting a Powerpoint file as a resource, I was finally able to fix that problem by converting the Powerpoint to xml and using that. I have considered doing the same for the PDF but I am referencing elements by field name which does not seem to work with XML PDFs. Can anyone help me out with this? Thanks in advance!

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• Eclipse randomly exits after installation of Blackberry plugin/SDK

  - by canadiancreed

  Hello all Since adding the Blackberry Java classes from their website into eclipse, I've had it where eclipse will randomly close, with no discernible pattern, rhyme, error or reason. Here is the environment/software packages that I am using: Windows XP SP2 Eclipse v3.5.1 Blackberry Java Plugin v1.1.1.200911111641-15 Blackberry Java SDK 4.5.0.21 I've tried the usual steps of complete uninstall and reinstallation of Eclipse and the accompanying plugins on multiple systems with the same configuration, including one that had a fresh install of Windows XP SP2. Upgrading to Eclipse 3.6 didn't work (the plugin wont' install as it's the wrong version), nor the downgrade to 3.4 for the same reason. I also increased the heap size to 512 (system has two gigs of memory) as some research into Eclipse doing this type of thing with Groovy was resolved that way, but again, no dice. Eclipse works great when the blackberry plugins are not installed, and no entries of errors or issues in the event log are helping to show what the issue with these plug-ins might be. So if anyone has ran into this issue, and even better, has a solution, I'd love to hear about it. Thanks in advance. EDIT: An additional to my issue, autoComplete with the Blackberry SDK seems to make this extremely unstable, like almost a guaranteed crash. Is this fixable at all?

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• Oracle rownum in db2 - Java data archiving

  - by HonorGod

  I have a data archiving process in java that moves data between db2 and sybase. FYI - This is not done through any import/export process because there are several conditions on each table that are available on run-time and so this process is developed in java. Right now I have single DatabaseReader and DatabaseWriter defined for each source and destination combination so that data is moved in multiple threads. I guess I wanted to expand this further where I can have Multiple DatabaseReaders and Multiple DatabaseWriters defined for each source and destination combination. So, for example if the source data is about 100 rows and I defined 10 readers and 10 writer, each reader will read 10 rows and give them to the writer. I hope process will give me extreme performance depending on the resources available on the server [CPU, Memory etc]. But I guess the problem is these source tables do not have primary keys and it is extremely difficult to grab rows in multiple sets. Oracle provides rownum concept and i guess the life is much simpler there....but how about db2? How can I achieve this behavior with db2? Is there a way to say fetch first 10 records and then fetch next 10 records and so on? Any suggestions / ideas ? Db2 Version - DB2 v8.1.0.144 Fix Pack Num - 16 Linux

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• What is the best way to send structs containing enum values via sockets in C.

  - by Axel

  I've lots of different structs containing enum members that I have to transmit via TCP/IP. While the communication endpoints are on different operating systems (Windows XP and Linux) meaning different compilers (gcc 4.x.x and MSVC 2008) both program parts share the same header files with type declarations. For performance reasons, the structures should be transmitted directly (see code sample below) without expensively serializing or streaming the members inside. So the question is how to ensure that both compilers use the same internal memory representation for the enumeration members (i.e. both use 32-bit unsigned integers). Or if there is a better way to solve this problem... //type and enum declaration typedef enum { A = 1, B = 2, C = 3 } eParameter; typedef enum { READY = 400, RUNNING = 401, BLOCKED = 402 FINISHED = 403 } eState; #pragma pack(push,1) typedef struct { eParameter mParameter; eState mState; int32_t miSomeValue; uint8_t miAnotherValue; ... } tStateMessage; #pragma pack(pop) //... send via socket tStateMessage msg; send(iSocketFD,(void*)(&msg),sizeof(tStateMessage)); //... receive message on the other side tStateMessage msg_received; recv(iSocketFD,(void*)(&msg_received),sizeof(tStateMessage)); Additionally... Since both endpoints are little endian maschines, endianess is not a problem here. And the pack #pragma solves alignment issues satisfactorily. Thx for your answers, Axel

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• Debugging SQL Server Slowness: Same Database, Different Servers

  - by Craig Walker

  For a while now we've been having anecdotal slowness on our newly-minted (VMWare-based) SQL Server 2005 database servers. Recently the problem has come to a head and I've started looking for the root cause of the issue. Here's the weird part: on the stored procedure that I'm using as a performance test case, I get a 30x difference in the execution speed depending on which DB server I run it on. This is using the same database (mdf) and log (ldf) files, detached, copied, and reattached from the slow server to the fast one. This doesn't appear to be a (virtualized) hardware issue: he slow server has 4x the CPU capacity and 2x the memory as the fast one. As best as I can tell, the problem lies in the environment/configuration of the servers (either operating system or SQL Server installation). However, I've checked a bunch of variables (SQL Server config options, running services, disk fragmentation) and found nothing that has made a difference in testing. What things should I be looking at? What tools can I use to investigate why this is happening?

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• EXC_BAD_ACCESS when executing ABAddressBookSave !

  - by Horatiu Paraschiv

  Hi everybody, I'm trying to create a new contact and add it to the AddressBook but when I get to the ABAddressSave line of code I get EXC_BAD_ACCESS. I cannot see what am I doing wrong, I enabled NSZombie to check if this is a memory related error but it didn't spot any. Can anybody tell me what is wrong with this code? Thank you in advance! CFErrorRef error = NULL; ABAddressBookRef iPhoneAddressBook = ABAddressBookCreate(); ABRecordRef newRecord = ABPersonCreate(); ABRecordSetValue(newRecord, kABPersonFirstNameProperty, @"Xxxxxx", &error); ABRecordSetValue(newRecord, kABPersonURLProperty, @"Yyyyyy", &error); //Add phone numbers to record ABMutableMultiValueRef phones = ABMultiValueCreateMutable(kABMultiStringPropertyType); ABMultiValueAddValueAndLabel(phones, @"1-555-555-5555", kABWorkLabel, NULL); ABRecordSetValue(newRecord, kABPersonPhoneProperty, phones, &error); CFRelease(phones); //Add email address to record ABMutableMultiValueRef emails = ABMultiValueCreateMutable(kABMultiStringPropertyType); ABMultiValueAddValueAndLabel(emails, @"[email protected]", kABWorkLabel, NULL); ABRecordSetValue(newRecord, kABPersonEmailProperty, emails, &error); CFRelease(emails); ABMutableMultiValueRef multiAddress = ABMultiValueCreateMutable(kABMultiDictionaryPropertyType); NSMutableDictionary *addressDict = [[NSMutableDictionary alloc] init]; [addressDict setObject:@"xxx1" forKey:(NSString *)kABPersonAddressStreetKey]; [addressDict setObject:@"xxx2" forKey:(NSString *)kABPersonAddressCityKey]; [addressDict setObject:@"xxx3" forKey:(NSString *)kABPersonAddressStateKey]; [addressDict setObject:@"xxx4" forKey:(NSString *)kABPersonAddressZIPKey]; ABMultiValueAddValueAndLabel(multiAddress, addressDict, kABWorkLabel, NULL); ABRecordSetValue(newRecord, kABPersonAddressProperty, multiAddress, &error); CFRelease(multiAddress); [addressDict release]; ABAddressBookAddRecord(iPhoneAddressBook, newRecord, &error); ABAddressBookSave(iPhoneAddressBook, NULL); if(error != nil){ NSLog(@"Error creating contact:%@", error); }

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• Stack and Hash joint

  - by Alexandru

  I'm trying to write a data structure which is a combination of Stack and HashSet with fast push/pop/membership (I'm looking for constant time operations). Think of Python's OrderedDict. I tried a few things and I came up with the following code: HashInt and SetInt. I need to add some documentation to the source, but basically I use a hash with linear probing to store indices in a vector of the keys. Since linear probing always puts the last element at the end of a continuous range of already filled cells, pop() can be implemented very easy without a sophisticated remove operation. I have the following problems: the data structure consumes a lot of memory (some improvement is obvious: stackKeys is larger than needed). some operations are slower than if I have used fastutil (eg: pop(), even push() in some scenarios). I tried rewriting the classes using fastutil and trove4j, but the overall speed of my application halved. What performance improvements would you suggest for my code? What open-source library/code do you know that I can try?

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• Joining on a common table, how do you get a FULL OUTER JOIN to expand on another table?

  - by stimpy77

  I've scoured StackOverflow and Google for an answer to this problem. I'm trying to create a Microsot SQL Server 2008 view. Not a stored procedure. Not a function. Just a query (i.e. a view). I have three tables. The first table defines a common key, let's say "CompanyID". The other two tables have a sometimes-common field, let's say "EmployeeName". I want a single table result that, when my WHERE clause says "WHERE CompanyID = 12" looks like this: CompanyID | TableA | TableB 12 | John Doe | John Doe 12 | Betty Sue | NULL 12 | NULL | Billy Bob I've tried a FULL OUTER JOIN that looks like this: SELECT Company.CompanyID, TableA.EmployeeName, TableB.EmployeeName FROM Company FULL OUTER JOIN TableA ON Company.CompanyID = TableA.CompanyID FULL OUTER JOIN TableB ON Company.CompanyID = TableB.CompanyID AND (TableA.EmployeeName IS NULL OR TableB.EmployeeName IS NULL OR TableB.EmployeeName = TableA.EmployeeName) I'm only getting the NULL from one matched table, I'm not getting the expansion for the other table. In the above sample, I'm basically only getting the first and third rows and not the second. Can someone help me create this query and show me how this is done correctly? BTW I already have a stored procedure that looks very clean and populates an in-memory table, but that isn't what I want. Thanks.

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• LINQ-to-SQL IN/Contains() for Nullable<T>

  - by Craig Walker

  I want to generate this SQL statement in LINQ: select * from Foo where Value in ( 1, 2, 3 ) The tricky bit seems to be that Value is a column that allows nulls. The equivalent LINQ code would seem to be: IEnumerable<Foo> foos = MyDataContext.Foos; IEnumerable<int> values = GetMyValues(); var myFoos = from foo in foos where values.Contains(foo.Value) select foo; This, of course, doesn't compile, since foo.Value is an int? and values is typed to int. I've tried this: IEnumerable<Foo> foos = MyDataContext.Foos; IEnumerable<int> values = GetMyValues(); IEnumerable<int?> nullables = values.Select( value => new Nullable<int>(value)); var myFoos = from foo in foos where nullables.Contains(foo.Value) select foo; ...and this: IEnumerable<Foo> foos = MyDataContext.Foos; IEnumerable<int> values = GetMyValues(); var myFoos = from foo in foos where values.Contains(foo.Value.Value) select foo; Both of these versions give me the results I expect, but they do not generate the SQL I want. It appears that they're generating full-table results and then doing the Contains() filtering in-memory (ie: in plain LINQ, without -to-SQL); there's no IN clause in the DataContext log. Is there a way to generate a SQL IN for Nullable types?

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• Grails - Simple hasMany Problem - How does 'save' work?

  - by gav

  My problem is this: I want to create a grails domain instance, defining the 'Many' instances of another domain that it has. I have the actual source in a Google Code Project but the following should illustrate the problem. class Person { String name static hasMany[skills:Skill] static constraints = { id (visible:false) skills (nullable:false, blank:false) } } class Skill { String name String description static constraints = { id (visible:false) name (nullable:false, blank:false) description (nullable:false, blank:false) } } If you use this model and def scaffold for the two Controllers then you end up with a form like this that doesn't work; My own attempt to get this to work enumerates the Skills as checkboxes and looks like this; But when I save the Volunteer the skills are null! This is the code for my save method; def save = { log.info "Saving: " + params.toString() def skills = params.skills log.info "Skills: " + skills def volunteerInstance = new Volunteer(params) log.info volunteerInstance if (volunteerInstance.save(flush: true)) { flash.message = "${message(code: 'default.created.message', args: [message(code: 'volunteer.label', default: 'Volunteer'), volunteerInstance.id])}" redirect(action: "show", id: volunteerInstance.id) log.info volunteerInstance } else { render(view: "create", model: [volunteerInstance: volunteerInstance]) } } This is my log output (I have custom toString() methods); 2010-05-10 21:06:41,494 [http-8080-3] INFO bumbumtrain.VolunteerController - Saving: ["skills":["1", "2"], "name":"Ian", "_skills":["", ""], "create":"Create", "action":"save", "controller":"volunteer"] 2010-05-10 21:06:41,495 [http-8080-3] INFO bumbumtrain.VolunteerController - Skills: [1, 2] 2010-05-10 21:06:41,508 [http-8080-3] INFO bumbumtrain.VolunteerController - Volunteer[ id: null | Name: Ian | Skills [Skill[ id: 1 | Name: Carpenter ] , Skill[ id: 2 | Name: Sound Engineer ] ]] Note that in the final log line the right Skills have been picked up and are part of the object instance. When the volunteer is saved the 'Skills' are ignored and not commited to the database despite the in memory version created clearly does have the items. Is it not possible to pass the Skills at construction time? There must be a way round this? I need a single form to allow a person to register but I want to normalise the data so that I can add more skills at a later time. If you think this should 'just work' then a link to a working example would be great. Hope this makes sense, thanks in advance! Gav

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• IoC - Dynamic Composition of object instances

  - by Joshua Starner

  Is there a way using IoC, MEF [Imports], or another DI solution to compose dependencies on the fly at object creation time instead of during composition time? Here's my current thought. If you have an instance of an object that raises events, but you are not creating the object once and saving it in memory, you have to register the event handlers every time the object is created. As far as I can tell, most IoC containers require you to register all of the classes used in composition and call Compose() to make it hook up all the dependencies. I think this may be horrible design (I'm dealing with a legacy system here) to do this due to the overhead of object creation, dependency injection, etc... but I was wondering if it was possible using one of the emergent IoC technologies. Maybe I have some terminology mixed up, but my goal is to avoid writing a framework to "hook up all the events" on an instance of an object, and use something like MEF to [Export] handlers (dependencies) that adhere to a very specific interface and [ImportMany] them into an object instance so my exports get called if the assemblies are there when the application starts. So maybe all of the objects could still be composed when the application starts, but I want the system to find and call all of them as the object is created and destroyed.

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• Am I deleting this properly?

  - by atch

  I have some struct: struct A { const char* name_; A* left_; A* right_; A(const char* name):name_(name), left_(nullptr), right_(nullptr){} A(const A&); //A(const A*);//ToDo A& operator=(const A&); ~A() { /*ToDo*/ }; }; /*Just to compile*/ A& A::operator=(const A& pattern) { //check for self-assignment if (this != &pattern) { void* p = new char[sizeof(A)]; } return *this; } A::A(const A& pat) { void* p = new char[sizeof(A)]; A* tmp = new (p) A("tmp"); tmp->~A(); delete tmp;//I WONDER IF HERE I SHOULD USE DIFFERENT delete[]? } int _tmain(int argc, _TCHAR* argv[]) { A a("a"); A b = a; cin.get(); return 0; } Guys I know this is far from ideal and far from finished. But please don't tell me the answer how to do it properly. I'm trying to figure it out myself. The only think I would like to know if I'm deleting my memory in proper way. Thanks.

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• How can I get PowerShell Added-Types to use Added References

  - by Scott Weinstein

  I'm working on a PoSh project that generates CSharp code, and then Add-Types it into memory. The new types use existing types in an on disk DLL, which is loaded via Add-Type. All is well and good untill I actualy try to invoke methods on the new types. Here's an example of what I'm doing: $PWD = "." rm -Force $PWD\TestClassOne* $code = " namespace TEST{ public class TestClassOne { public int DoNothing() { return 1; } } }" $code | Out-File tcone.cs Add-Type -OutputAssembly $PWD\TestClassOne.dll -OutputType Library -Path $PWD\tcone.cs Add-Type -Path $PWD\TestClassOne.dll $a = New-Object TEST.TestClassOne "Using TestClassOne" $a.DoNothing() "Compiling TestClassTwo" Add-Type -Language CSharpVersion3 -TypeDefinition " namespace TEST{ public class TestClassTwo { public int CallTestClassOne() { var a = new TEST.TestClassOne(); return a.DoNothing(); } } }" -ReferencedAssemblies $PWD\TestClassOne.dll "OK" $b = New-Object TEST.TestClassTwo "Using TestClassTwo" $b.CallTestClassOne() Running the above script gives the following error on the last line: Exception calling "CallTestClassOne" with "0" argument(s): "Could not load file or assembly 'TestClassOne,...' or one of its dependencies. The system cannot find the file specified." At AddTypeTest.ps1:39 char:20 + $b.CallTestClassOne <<<< () + CategoryInfo : NotSpecified: (:) [], MethodInvocationException + FullyQualifiedErrorId : DotNetMethodException What am I doing wrong?

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• Best way to manipulate and compare strings

  - by vtortola

  I'm developing a REST service, so a request could be something like this: /Data/Main/Table=Customers/ I need to get the segments one by one, and for each segment I will decide wich object I'm going to use, after I'll pass to that object the rest of the query so it can decide what to do next. Basically, the REST query is a path on a tree :P This imply lots String operations (depending on the query complexity), but StringBuilder is useful just for concatenations and remove, you cannot perform a search with IndexOf or similar. I've developed this class that fulfill my requirement, but the problem is that is manipulating Strings, so every time I get one segment ... I'll create extra Strings because String is an inmutable data type: public class RESTQueryParser { String _query; public RESTQueryParser(String query) { _query = query; } public String GetNext() { String result = String.Empty; Int32 startPosition = _query.StartsWith("/", StringComparison.InvariantCultureIgnoreCase) ? 1 : 0; Int32 i = _query.IndexOf("/", startPosition, StringComparison.InvariantCultureIgnoreCase) - 1; if (!String.IsNullOrEmpty(_query)) { if (i < 0) { result = _query.Substring(startPosition, _query.Length - 1); _query = String.Empty; } else { result = _query.Substring(startPosition, i); _query = _query.Remove(0, i + 1); } } return result; } } The server should support a lot of calls, and the queries could be huge, so this is gonna be a very repetitive task. I don't really know how big is the impact on the memory and the performance, I've just readed about it in some books. Should I implement a class that manage a Char[] instead Strings and implement the methods that I want? Or should be ok with this one? Regular expressions maybe?

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• evaluation of a java thread dump

  - by raticulin

  I got a thread dump of one of my processes. It has a bunch of these threads. I guess they are keeping a bunch of memory so I am getting OOM. "Thread-8264" prio=6 tid=0x4c94ac00 nid=0xf3c runnable [0x4fe7f000] java.lang.Thread.State: RUNNABLE at java.util.zip.Inflater.inflateBytes(Native Method) at java.util.zip.Inflater.inflate(Inflater.java:223) - locked <0x0c9bc640 (a java.util.zip.Inflater) at org.apache.commons.compress.archivers.zip.ZipArchiveInputStream.read(ZipArchiveInputStream.java:235) at com.my.ZipExtractorCommonsCompress.extract(ZipExtractorCommonsCompress.java:48) at com.my.CustomThreadedExtractorWrapper$ExtractionThread.run(CustomThreadedExtractorWrapper.java:151) Locked ownable synchronizers: - None "Thread-8241" prio=6 tid=0x4c94a400 nid=0xb8c runnable [0x4faef000] java.lang.Thread.State: RUNNABLE at java.util.zip.Inflater.inflateBytes(Native Method) at java.util.zip.Inflater.inflate(Inflater.java:223) - locked <0x0c36b808 (a java.util.zip.Inflater) at org.apache.commons.compress.archivers.zip.ZipArchiveInputStream.read(ZipArchiveInputStream.java:235) at com.my.ZipExtractorCommonsCompress.extract(ZipExtractorCommonsCompress.java:48) at com.my.CustomThreadedExtractorWrapper$ExtractionThread.run(CustomThreadedExtractorWrapper.java:151) Locked ownable synchronizers: - None I am trying to find out how it arrived to this situation. CustomThreadedExtractorWrapper is a wrapper class that fires a thread to do some work (ExtractionThread, which uses ZipExtractorCommonsCompress to extract zip contents from a compressed stream). If the task is taking too long, ExtractionThread.interrupt(); is called to cancel the operation. I can see in my logs that the cancellation happened 25 times. And I see 21 of these threads in my dump. My questions: What is the status of these threads? Alive and running? Blocked somehow? They did not die with .interrupt() apparently? Is there a sure way to really kill a thread? What does really mean 'locked ' in the stack trace? Line 223 in Inflater.java is: public synchronized int inflate(byte[] b, int off, int len) { ... //return is line 223 return inflateBytes(b, off, len); }

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• iPhone programming - problem with CoreFoundation forking, PLEASE for the love of god help! lol

  - by Tom

  Hello all, I've been working on an iPhone for several months. It's a 2d shooting game akin to the old Smash TV type games. I'm doing everything alone and it has come out well so far, but now I am getting unpredictable crashes which seem to be related to CoreFoundation forking and not exec()ing, as the message THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONA LITY_YOU_MUST_EXEC__ always shows up somewhere in the debugger. Usually it shows up around a CFRunLoopRunSpecific and is related to either a timer firing or _InitializeTouchTapCount. I cannot figure out exactly what is causing the fork to occur. My main game loop is running on a timer, first updating all the logic and then drawing everything with openGL. There is nothing highly complex or unusual. I understand you cannot make CF calls on the childside of a fork, or access shared memory and things like that. I am not explicitly trying to fork anything. My question is: can anyone tell me what type of activity might cause CoreFoundation to randomly fork like this? I'd really like to finish this game and I don't know how to solve this problem. Thanks for any help.

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• Reading from serial port with Boost Asio?

  - by trikri

  Hi! I'm going to check for incoming messages (data packages) on the serial port, using Boost Asio. Each message will start with a header that is one byte long, and will specify which type of the message has been sent. Each different type of message has an own length. The function I'm about to write should check for new incoming messages continually, and when it finds one it should read it, and then some other function should parse it. I thought that the code might look something like this: void check_for_incoming_messages() { boost::asio::streambuf response; boost::system::error_code error; std::string s1, s2; if (boost::asio::read(port, response, boost::asio::transfer_at_least(0), error)) { s1 = streambuf_to_string(response); int msg_code = s1[0]; if (msg_code < 0 || msg_code >= NUM_MESSAGES) { // Handle error, invalid message header } if (boost::asio::read(port, response, boost::asio::transfer_at_least(message_lengths[msg_code]-s1.length()), error)) { s2 = streambuf_to_string(response); // Handle the content of s1 and s2 } else if (error != boost::asio::error::eof) { throw boost::system::system_error(error); } } else if (error != boost::asio::error::eof) { throw boost::system::system_error(error); } } Is boost::asio::streambuf is the right thing to use? And how do I extract the data from it so I can parse the message? I also want to know if I need to have a separate thread which only calls this function, so that it get called more often? Isn't there a risk for loosing data in between two calls to the function otherwise, because so much data comes in that it can't be stored in the serial ports memory? I'm using Qt as a widget toolkit and I don't really know how long time it needs to process all it's events.

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• How are you taking advantage of Multicore?

  - by tgamblin

  As someone in the world of HPC who came from the world of enterprise web development, I'm always curious to see how developers back in the "real world" are taking advantage of parallel computing. This is much more relevant now that all chips are going multicore, and it'll be even more relevant when there are thousands of cores on a chip instead of just a few. My questions are: How does this affect your software roadmap? I'm particularly interested in real stories about how multicore is affecting different software domains, so specify what kind of development you do in your answer (e.g. server side, client-side apps, scientific computing, etc). What are you doing with your existing code to take advantage of multicore machines, and what challenges have you faced? Are you using OpenMP, Erlang, Haskell, CUDA, TBB, UPC or something else? What do you plan to do as concurrency levels continue to increase, and how will you deal with hundreds or thousands of cores? If your domain doesn't easily benefit from parallel computation, then explaining why is interesting, too. Finally, I've framed this as a multicore question, but feel free to talk about other types of parallel computing. If you're porting part of your app to use MapReduce, or if MPI on large clusters is the paradigm for you, then definitely mention that, too. Update: If you do answer #5, mention whether you think things will change if there get to be more cores (100, 1000, etc) than you can feed with available memory bandwidth (seeing as how bandwidth is getting smaller and smaller per core). Can you still use the remaining cores for your application?

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• theoretical and practical matrix multiplication FLOP

  - by mjr

  I wrote traditional matrix multiplication in c++ and tried to measure and compare its theoretical and practical FLOP. As I know inner loop of MM has 2 operation therefore simple MM theoretical Flops is 2*n*n*n (2n^3) but in practice I get something like 4n^3 + number of operation which is 2 i.e. 6n^3 also if I just try to add up only one array a[i][j]++ practical flops then calculate like 3n^3 and not n^3 as you see again it is 2n^3 +1 operation and not 1 operation * n^3 . This is in case if I use 1D array in three nested loops as Matrix multiplication and compare flop, practical flop is the same (near) the theoretical flop and depend exactly as the number of operation in inner loop.I could not find the reason for this behaviour. what is the reason in both case? I know that theoretical flop is not the same as practical one because of some operations like load etc. system specification: Intel core2duo E4500 3700g memory L2 cache 2M x64 fedora 17 sample results: Matrix matrix multiplication 512*512 Real_time: 1.718368 Proc_time: 1.227672 Total flpops: 807,107,072 MFLOPS: 657.429016 Real_time: 3.608078 Proc_time: 3.042272 Total flpops: 807,024,448 MFLOPS: 265.270355 theoretical flop: 2*512*512*512=268,435,456 Practical flops= 6*512^3 =807,107,072 Using 1 dimensional array float d[size][size]:512 or any size for (int j = 0; j < size; ++j) { for (int k = 0; k < size; ++k) { d[k]=d[k]+e[k]+f[k]+g[k]+r; } } Real_time: 0.002288 Proc_time: 0.002260 Total flpops: 1,048,578 MFLOPS: 464.027161 theroretical flop: *4n^2=4*512^2=1,048,576* practical flop : 4n^2+overhead (other operation?)=1,048,578 3 loop version: Real_time: 1.282257 Proc_time: 1.155990 Total flpops: 536,872,000 MFLOPS: 464.426117 theoretical flop:4n^3 = 536,870,912 practical flop: *4n^3=4*512^3+overheads(other operation?)=536,872,000* thank you

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• Question - Setting dynamic HTML using Javascript to iFrames on Windows Mobile 6.1 - IE Mobile6

  - by swaroop

  Hi Experts, (excuse me if this is not the right forum to post - i couldn't find anything related to non-native programming and related to this topic) I Am trying to set a dynamic HTML into an iFrame on the webpage. I have tried a couple of things but none of them seem to work. I m able to read the innerHTML but can't seem to update it. // Able to read using document.getElementById('iFrameIdentifier').innerHTML; // On Desktop IE, this code works document.getElementById('iFrameId').contentWindow.document.open(); document.getElementById('iFrameId').contentWindow.document.write(dynamicHTML); document.getElementById('iFrameId').contentWindow.document.close(); Ideally the same function should work as how it works for div's but it says 'Object doesn't support this method or property". I have also tried document.getElementById('iFrameId').document.body.innerHTML. This apparently replaces the whole HTML of the page and not just the innerHTML. I have tried out a couple of things and they didn't work document.getElementById('iFrameId').body.innerHTML document.frames[0].document.body.innerHTML My purpose is to have a container element which can contain dynamic HTML that's set to it. I've been using it well till now when I observed that the setting innerHTML on a div is taking increasing amount of time because of the onClicks or other JS methods that are attached to the anchors and images in the dynamic HTML. Appears the JS methods or the HTML is some how not getting cleaned up properly (memory leak?) Also being discussed - http://www.experts-exchange.com/Programming/Languages/Scripting/JavaScript/Q_26185526.html#a32779090

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• "QFontEngine(Win) GetTextMetrics failed ()" error on 64-bit Windows

  - by David Murdoch

  I'll add 500 of my own rep as a bounty when SO lets me. I'm using wkhtmltopdf to convert HTML web pages to PDFs. This works perfectly on my 32-bit dev server [unfortunately, I can't ship my machine :-p ]. However, when I deploy to the web application's 64-bit server the following errors are displayed: C:\>wkhtmltopdf http://www.google.com google.pdf Loading pages (1/5) QFontEngine::loadEngine: GetTextMetrics failed () ] 10% QFontEngineWin: GetTextMetrics failed () QFontEngineWin: GetTextMetrics failed () QFontEngine::loadEngine: GetTextMetrics failed () QFontEngineWin: GetTextMetrics failed () QFontEngineWin: GetTextMetrics failed () QFontEngineWin: GetTextMetrics failed () QFontEngine::loadEngine: GetTextMetrics failed () ] 36% QFontEngineWin: GetTextMetrics failed () QFontEngineWin: GetTextMetrics failed () // ...etc.... and the PDF is created and saved... just WITHOUT text. All form-fields, images, borders, tables, divs, spans, ps, etc are rendered accurately...just void of any text at all. Server information: Windows edition: Windows Server Standard Service Pack 2 Processor: Intel Xeon E5410 @ 2.33GHz 2.33 GHz Memory: 8.00 GB System type: 64-bit Operating System Can anyone give me a clue as to what is happening and how I can fix this? Also, I wasn't sure what to tag/title this question with...so if you can think of better tags/title comment them or edit the question. :-)

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• x86 CMP Instruction Difference

  - by Pindatjuh

  Question What is the (non-trivial) difference between the following two x86 instructions? 39 /r CMP r/m32,r32 Compare r32 with r/m32 3B /r CMP r32,r/m32 Compare r/m32 with r32 Background I'm building a Java assembler, which will be used by my compiler's intermediate language to produce Windows-32 executables. Currently I have following code: final ModelBase mb = new ModelBase(); // create new memory model mb.addCode(new Compare(Register.ECX, Register.EAX)); // add code mb.addCode(new Compare(Register.EAX, Register.ECX)); // add code final FileOutputStream fos = new FileOutputStream(new File("test.exe")); mb.writeToFile(fos); fos.close(); To output a valid executable file, which contains two CMP instruction in a TEXT-section. The executable outputted to "text.exe" will do nothing interesting, but that's not the point. The class Compare is a wrapper around the CMP instruction. The above code produces (inspecting with OllyDbg): Address Hex dump Command 0040101F |. 3BC8 CMP ECX,EAX 00401021 |. 3BC1 CMP EAX,ECX The difference is subtle: if I use the 39 byte-opcode: Address Hex dump Command 0040101F |. 39C1 CMP ECX,EAX 00401021 |. 39C8 CMP EAX,ECX Which makes me wonder about their synonymity and why this even exists.

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• RegistryKey ValueCount/SubKeyCount wrong

  - by Mark J Miller

  I am trying to query the following registry key values: HKLM\SOFTWARE\Microsoft\MSSQLServer\Client\SharedMemoryOn HKLM\SOFTWARE\Microsoft\MSSQLServer\Client\SuperSocketNetLib\ProtocolOrder But depending on which machine I'm running the program the query returns null. When I debug on my local machine and I inspect the value for ValueCount for: HKLM\SOFTWARE\Microsoft\MSSQLServer\Client HKLM\SOFTWARE\Microsoft\MSSQLServer\Client\SuperSocketNetLib The count is 0 and OpenSubKey returns null. I am a domain admin, in the local administrators group and have added the following to my app.manifest: <requestedExecutionLevel level="requireAdministrator" uiAccess="false" /> Any idea why? private static void ValidateSqlClientSettings() { Console.WriteLine("\r\n/////////////// LOCAL SQL CLIENT PROTOCOLS ////////////////"); RegistryKey keyHKLM = Registry.LocalMachine; ///TODO: nullreferenceexception - connect to remote machine and find out why RegistryKey sqlClientKey = keyHKLM.OpenSubKey(@"SOFTWARE\Microsoft\MSSQLServer\Client"); if (sqlClientKey == null) { WriteLine2Console(@"WARNING: unable to read registry key '{0}\SOFTWARE\Microsoft\MSSQLServer\Client'", ConsoleColor.Yellow); } var cliKeyNames = from k in sqlClientKey.GetSubKeyNames() where k == "SuperSocketNetLib" select k; ///TODO: find out why these values are always missing (even if I can see them in regedit) Console.Write("Shared Memory Disabled (cliconfg): "); if (Convert.ToBoolean(sqlClientKey.GetValue("SharedMemoryOn"))) WriteLine2Console("FAILED", ConsoleColor.Red); else if(sqlClientKey.GetValue("SharedMemoryOn") == null) WriteLine2Console(String.Format("WARNING - unable to read '{0}\\SharedMemoryOn'", sqlClientKey.Name), ConsoleColor.Yellow); else WriteLine2Console("PASS", ConsoleColor.Green); Console.Write("Client Protocol Order (cliconfg - tcp first): "); foreach (string cliKey in cliKeyNames) { RegistryKey subKey = sqlClientKey.OpenSubKey(cliKey); object order = subKey.GetValue("ProtocolOrder"); if (order != null && order.ToString().StartsWith("tcp") == false) { WriteLine2Console("FAILED", ConsoleColor.Red); } else if (order == null) { WriteLine2Console(String.Format("WARNING - unable to read '{0}\\ProtocolOrder'", subKey.Name), ConsoleColor.Yellow); } else { WriteLine2Console("PASS", ConsoleColor.Green); } subKey.Close(); } sqlClientKey.Close(); keyHKLM.Close(); }

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• JSON: Jackson stream parser - is it really worth it?

  - by synic

  I'm making pretty heavy use of JSON parsing in an app I'm writing. Most of what I have done is already implemented using Android's built in JSONObject library (is it json-lib?). JSONObject appears to create instances of absolutely everything in the JSON string... even if I don't end up using all of them. My app currently runs pretty well, even on a G1. My question is this: are the speed and memory benefits from using a stream parser like Jackson worth all the trouble? By trouble, I mean this: As far as I can tell, there are three downsides to using Jackson instead of the built in library: Dependency on an external library. This makes your .apk bigger in the end. Not a huge deal. Your app is more fragile. Since the parsing is not done automatically, it is more vulnerable to changes in the JSON text that it's parsing. I'm extremely worried that malformed JSON will result in infinite loops (as pull parsing requires a lot of while loops). Writing code to parse JSON via a stream parser is ugly and tedious.

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