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• Which Computer Organization & Architecture book is good for me?

  - by claws

  I'm always interested in learning the inner working of things. I started with C programming and then learnt Operating systems (from stallings) and then linkers & loaders and then assembly language after reading these now I want to go into little more depth. Computer Architecture. I feel that makes everything clear. As per SO archives these are the two good books: Computer Architecture: A Quantitative Approach, 4th Edition Computer Organization and Design, Fourth Edition, ~ David A. Patterson, John L. Hennessy But I've browsed through the contents of these books and found that they don't exactly meet my needs. I want to learn more about caches, Memory Management Unit , mapping b/w virtual memory & physical memory I'm no way interested in other ISAs like MIPS etc.. I'm IA32 and X86-64 fan and I want to stick to it. I'm not a hardware developer I don't want to details like circuit diagrams or How is L1, L2 & L3 caches are implemented? I want to know the parallel processing technologies like HyperThreading at the architecture level but again I don't want to design them. I liked the table of Contents of - Computer Architecture: A Quantitative Approach, 4th Edition but Quantitave Approach? Seriously?? I want to know the details of current technologies and I dont want to spend reading 200 pages of outdated old technologies ( I experienced this while learning ASM}

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• Fancybox "close" hangs/delays in IE7/8

  - by Kerri

  I'm having an issue with IE7/8 only on a development site: when closing the Fancybox, there is a major delay, sometimes about ten seconds or so, sometimes much longer (like a minute). Some things that might be relevant: • Using fancybox 1.3.1 • Works perfectly on all other browsers (FF, Safari, Opera, Chrome) • The loaded iframe contains a flash "virtual tour" • There are no errors reported in IE's Dev Toolbar or in DebugBar • The fancybox renders perfectly in IE, and after it has closed, there is not a problem loading it again. The closing seems to be the only issue. (That, and that it crashed the client's browser once, but I'm inclined to believe that had more to do with the content of the iframe than fancybox). I changed the link to the iFrame to something simpler (google), and it closed with no problem. So it does seem to have something to do with a conflict with the content of the iframe. The call: $("a#tourbox").fancybox({ "width": 750, "height" : 575, "autoScale": false, "type": "iframe" }); The HTML: <a id="tourbox" href="http://tour.circlepix.com/tour.htm?id=670335"><img src="sites/all/themes/removed/images/banquets-vtour.jpg" alt="Virtual Tour" /></a> Here's a link to the page with the problem: http://s93571.gridserver.com/banquets Click on the "Go to 360° Virtual Tour" image. Here's the page it loads: http://tour.circlepix.com/tour.htm?id=670335 I'd greatly appreciate any clues or ideas of what might be the issue. I couldn't find any other discussions with a similar problem. Thanks for any insights!

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• Perl XML SAX parser emulating XML::Simple record for record

  - by DVK

  Short Q summary: I am looking a fast XML parser (most likely a wrapper around some standard SAX parser) which will produce per-record data structure 100% identical to those produced by XML::Simple. Details: We have a large code infrastructure which depends on processing records one-by-one and expects the record to be a data structure in a format produced by XML::Simple since it always used XML::Simple since early Jurassic era. An example simple XML is: <root> <rec><f1>v1</f1><f2>v2</f2></rec> <rec><f1>v1b</f1><f2>v2b</f2></rec> <rec><f1>v1c</f1><f2>v2c</f2></rec> </root> And example rough code is: sub process_record { my ($obj, $record_hash) = @_; # do_stuff } my $records = XML::Simple->XMLin(@args)->{root}; foreach my $record (@$records) { $obj->process_record($record) }; As everyone knows XML::Simple is, well, simple. And more importantly, it is very slow and a memory hog - due to being a DOM parser and needing to build/store 100% of data in memory. So, it's not the best tool for parsing an XML file consisting of large amount of small records record-by-record. However, re-writing the entire code (which consist of large amount of "process_record"-like methods) to work with standard SAX parser seems like an big task not worth the resources, even at the cost of living with XML::Simple. What I'm looking for is an existing module which will probably be based on a SAX parser (or anything fast with small memory footprint) which can be used to produce $record hashrefs one by one based on the XML pictured above that can be passed to $obj->process_record($record) and be 100% identical to what XML::Simple's hashrefs would have been. I don't care much what the interface of the new module is - e.g whether I need to call next_record() or give it a callback coderef accepting a record.

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• NPTL Default Stack Size Problem

  - by eyazici

  Hello, I am developing a multithread modular application using C programming language and NPTL 2.6. For each plugin, a POSIX thread is created. The problem is each thread has its own stack area, since default stack size depends on user's choice, this may results in huge memory consumption in some cases. To prevent unnecessary memory usage I used something similar to this to change stack size before creating each thread: pthread_attr_t attr; pthread_attr_init (&attr); pthread_attr_getstacksize(&attr, &st1); if(pthread_attr_setstacksize (&attr, MODULE_THREAD_SIZE) != 0) perror("Stack ERR"); pthread_attr_getstacksize(&attr, &st2); printf("OLD:%d, NEW:%d - MIN: %d\n", st1, st2, PTHREAD_STACK_MIN); pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); /* "this" is static data structure that stores plugin related data */ pthread_create(&this->runner, &attr, (void *)(void *)this->run, NULL); EDIT I: pthread_create() section added. This did not work work as I expected, the stack size reported by pthread_attr_getstacksize() is changed but total memory usage of the application (from ps/top/pmap output) did not changed: OLD:10485760, NEW:65536 - MIN: 16384 When I use ulimit -s MY_STACK_SIZE_LIMIT before starting application I achieve the expected result. My questions are: 1-) Is there any portable(between UNIX variants) way to change (default)thread stack size after starting application(before creating thread of course)? 2-) Is it possible to use same stack area for every thread? 3-) Is it possible completely disable stack for threads without much pain?

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• Quartz compositions created in Snow Leopard (10.6) doesn't work in Leopard (10.5) despite testing in

  - by adib

  Hi I have a reasonably advanced (many patches and subpatches) quartz composition that was created in Snow Leopard but doesn't run well (many elements are not rendered) in Leopard. The composition tested OK via Quartz Composer's Test in Runtime option and works fine for both Leopard 32-bits and Leopard 64-bits (menu item "File | Test in Runtime | Leopard 32-bits". In an actual Leopard (32-bits) system, a lot of elements are not rendered in the quartz composition. Below are the log file excerpt when the composition is run in QuickTime Player under Leopard: QuickTime Player[134] *** <QCNodeManager | namespace = "com.apple.QuartzComposer" | 335 nodes>: Patch with name "/units to pixels" is missing QuickTime Player[134] *** Message from <QCPatch = 0x06D82880 "(null)">:Cannot create node of class "/units to pixels" and identifier "(null)" QuickTime Player[134] *** Message from <QCPatch = 0x06D7C130 "(null)">:Cannot create node of class "/resize image to target" and identifier "(null)" QuickTime Player[134] *** Message from <QCPatch = 0x06D7C130 "(null)">:Cannot create connection from ["outputValue" @ "Math_1"] to ["Target_Pixels" @ "Patch_2"] The patch "units to pixels" is a system patch in Snow Leopard whereas the patch "resize image to target" is a custom virtual patch located in my home directory. It seems that we can cross out problems in which the composition is referencing a missing virtual patch. I have tested the composition under another user's account and it ran fine which shows that it already embeds the "resize image to target" virtual patch that is located in my home directory. I'm really puzzled why the composition passes the Leopard Runtime test but yet fail to run in an actual Leopard OS? Is there a post-processing step that I need to run to the composition file? Is there any way to make this patch more compatible with Leopard? Thanks in advance.

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• Inherited fluent nhibenate mapping issue

  - by Aim Kai

  I have an interesting issue today!! Basically I have two classes. public class A : B { public virtual new ISet<DifferentItem> Items {get;set;} } public class B { public virtual int Id {get;set;} public virtual ISet<Item> Items {get;set;} } The subclass A hides the base class B property, Items and replaces it with a new property with the same name and a different type. The mappings for these classes are public class AMapping : SubclassMap<A> { public AMapping() { HasMany(x=>x.Items) .LazyLoad() .AsSet(); } } public class BMapping : ClassMap<B> { public BMapping() { Id(x=>x.Id); HasMany(x=>x.Items) .LazyLoad() .AsSet(); } } However when I run my unit test to check the mapping I get the following exception: Tests the A mapping: NHibernate.PropertyAccessException : Invalid Cast (check your mapping for property type mismatches); setter of A ---- System.InvalidCastException : Unable to cast object of type 'NHibernate.Collection.Generic.PersistentGenericSet1[Item]' to type 'Iesi.Collections.Generic.ISet1[DifferentItem]'. Anyone have any ideas? Clearly it is something to do with the type of the collection on the sub-class. But I skimmed through the available options on the mapping class and nothing stood out as being the solution here.

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• Delphi 2009: How do I prevent network application from leaking critical section?

  - by eed3si9n

  As part of Vista certification, Microsoft wants to make sure that an application exits without holding on to a lock (critical section): TEST CASE 31. Verify application does not break into a debugger with the specified AppVerifier checks (Req:3.2) As it turns out, network applications built using Delphi 2009 does break into the debugger, which displays unhelpful message as follows: (1214.1f10): Break instruction exception - code 80000003 (first chance) eax=00000001 ebx=07b64ff8 ecx=a6450000 edx=0007e578 esi=0017f7e0 edi=80000003 eip=77280004 esp=0017f780 ebp=0017f7ac iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000246 *** ERROR: Symbol file could not be found. Defaulted to export symbols for C:\Windows\SysWOW64\ntdll.dll - ntdll!DbgBreakPoint: 77280004 cc int 3 After hitting Go button several times, you come across the actual error: ======================================= VERIFIER STOP 00000212: pid 0x18A4: Freeing virtual memory containing an active critical section. 076CC5DC : Critical section address. 01D0191C : Critical section initialization stack trace. 075D0000 : Memory block address. 00140000 : Memory block size. ======================================= This verifier stop is continuable. After debugging it use `go' to continue. ======================================= Given that my code does not leak TCriticalSection, how do I prevent Delphi from doing so.

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• resolving overloads in boost.python

  - by swarfrat

  I have a C++ class like this: class ConnectionBase { public: ConnectionBase(); template <class T> Publish(const T&); private: virtual void OnEvent(const Overload_a&) {} virtual void OnEvent(const Overload_b&) {} }; My templates & overloads are a known fixed set of types at compile time. The application code derives from ConnectionBase and overrides OnEvent for the events it cares about. I can do this because the set of types is known. OnEvent is private because the user never calls it, the class creates a thread that calls it as a callback. The C++ code works. I have wrapped this in boost.python, I can import it and publish from python. I want do create the equivalent of the following in python : class ConnectionDerived { public: ConnectionDerived(); private: virtual void OnEvent(const Overload_b&) { // application code } }; But ... since python isn't typed, and all the boost.python examples I've seen dealing with internals are on the C++ side, I'm a little puzzled as to how to do this. How do I override specific overloads?

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• Problem in cropping the UIImage using CGContext?

  - by Rajendra Bhole

  Hi, I developing the simple UIApplication in which i want to crop the UIImage (in .jpg format) with help of CGContext. The developed code till now as follows, CGImageRef graphicOriginalImage = [originalImage.image CGImage]; UIGraphicsBeginImageContext(originalImage.image.size); CGContextRef ctx = UIGraphicsGetCurrentContext(); CGBitmapContextCreateImage(graphicOriginalImage); CGFloat fltW = originalImage.image.size.width; CGFloat fltH = originalImage.image.size.height; CGFloat X = round(fltW/4); CGFloat Y =round(fltH/4); CGFloat width = round(X + (fltW/2)); CGFloat height = round(Y + (fltH/2)); CGContextTranslateCTM(ctx, 0, image.size.height); CGContextScaleCTM(ctx, 1.0, -1.0); CGRect rect = CGRectMake(X,Y ,width ,height); CGContextDrawImage(ctx, rect, graphicOriginalImage); croppedImage = UIGraphicsGetImageFromCurrentImageContext(); return croppedImage; } The above code is worked fine but it can't crop image. The original image memory and cropped image memory i will got same(equal to original image memory). The above code is right for cropping the image?????????????????? How i cropping the image (in behind pixels should also be crop) from the center of the image???????????? I already wasting a lot of time for developing the above code , but i didn't get answer or way to find out how to crop the image.Thanks for sending me answer in advanced.

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• Where are tables in Mnesia located?

  - by Sanoj

  I try to compare Mnesia with more traditional databases. As I understand it tables in Mnesia can be located to: ram_copies - tables are stored in RAM only, so no durability as in ACID. disc_copies - tables are located on disc and a copy is located in RAM, so the table can not be bigger than the available memory? disc_only_copies - tables are located to disc only, so no caching in memory and worse performance? And the size of the table are limited to the size of dets or the table has to be fragmented. So if I want the performance of doing reads from RAM and the durability of writes to disc, then the size of the tables are very limited compared to a traditional RDBMS like MySQL or PostgreSQL. I know that Mnesia aren't meant to replace traditional RDBMS:s, but can it be used as a big RDBMS or do I have to look for another database? The server I will use is a VPS with limited amount of memory, around 512MB, but I want good database performance. Are disc_copies and the other types of tables in Mnesia so limited as I have understood?

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• Large Reports for MSRS

  - by Greg Lorenz

  I have a report that needs to be able to render a very large amount of pages (about 4500 in this instance) in a web browser. The total time needed to finish on the report server from start time to end time is about 30 mins for the instance that I am looking at. Does anyone know what options exist for handling the rendering of such a large report in a web browser? In terms of looking into how this can be resolved I have already performed the following tasks. The report gets its data off of a database table that already has the data flattened to the point that the TimeDataRetrieval on the report server is 17812 or about 18 secs. The report itself has been reformatted to include the least expensive report objects that it can in order to render the data in the correct format. I basically consists of a table with about 4 nested tables and thats it. We were trying to accomplish this on a 2005 report server but continued to run into memory issues that were not feasible for our clients. In response to that we moved this onto a 2008 report server to take advantage of the fact that it uses the file system instead of memory and finally were able to get this to work without running out of the available memory but of course it takes much longer.

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• What file format can represent an uncompressed raster image at 48 or 64 bits per pixel?

  - by finnw

  I am creating screenshots under Windows and using the LockBits function from GDI+ to extract the pixel data, which will then be written to a file. To maximise performance I am also: Using the same PixelFormat as the source bitmap, to avoid format conversion Using the ImageLockModeUserInputBuf flag to extract the pixel data into a pre-allocated buffer This pre-allocated buffer (pointed to by BitmapData::Scan0) is part of a memory-mapped file (to avoid copying the pixel data again.) I will also be writing the code that reads the file, so I can use (or invent) any format I wish. However I would prefer to use a well-known format that existing programs (ideally web browsers) are able to read, because that means I can visually confirm that the images are correct before writing the code for the other program (that reads the image.) I have implemented this successfully for the PixelFormat32bppRGB format, which matches the format of a 32bpp BMP file, so if I extract the pixel data directly into the memory-mapped BMP file and prefix it with a BMP header I get a valid BMP image file that can be opened in Paint and most browsers. Unfortunately one of the machines I am testing on returns pixels in PixelFormat64bppPARGB format (presumably this is influenced by the video adapter driver) and there is no corresponding BMP pixel format for this. Converting to a 16, 24 or 32bpp BMP format slows the program down considerably (as well as being lossy) so I am looking for a file format that can use this pixel format without conversion, so I can extract directly into the memory-mapped file as I have done with the 32bpp format. What raster image file formats support 48bpp and/or 64bpp?

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• Perl XML SAX parser emulating XML::Simple record for record

  - by DVK

  Short Q summary: I am looking a fast XML parser (most likely a wrapper around some standard SAX parser) which will produce per-record data structure 100% identical to those produced by XML::Simple. Details: We have a large code infrastructure which depends on processing records one-by-one and expects the record to be a data structure in a format produced by XML::Simple since it always used XML::Simple since early Jurassic era. An example simple XML is: <root> <rec><f1>v1</f1><f2>v2</f2></rec> <rec><f1>v1b</f1><f2>v2b</f2></rec> <rec><f1>v1c</f1><f2>v2c</f2></rec> </root> And example rough code is: sub process_record { my ($obj, $record_hash) = @_; # do_stuff } my $records = XML::Simple->XMLin(@args)->{root}; foreach my $record (@$records) { $obj->process_record($record) }; As everyone knows XML::Simple is, well, simple. And more importantly, it is very slow and a memory hog - due to being a DOM parser and needing to build/store 100% of data in memory. So, it's not the best tool for parsing an XML file consisting of large amount of small records record-by-record. However, re-writing the entire code (which consist of large amount of "process_record"-like methods) to work with standard SAX parser seems like an big task not worth the resources, even at the cost of living with XML::Simple. What I'm looking for is an existing module which will probably be based on a SAX parser (or anything fast with small memory footprint) which can be used to produce $record hashrefs one by one based on the XML pictured above that can be passed to $obj->process_record($record) and be 100% identical to what XML::Simple's hashrefs would have been.

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• WCF Certificates without Certificate Store

  - by Kane

  My team is developing a number of WPF plug-ins for a 3rd party thick client application. The WPF plug-ins use WCF to consume web services published by a number of TIBCO services. The thick client application maintains a separate central data store and uses a proprietary API to access the data store. The thick client and WPF plug-ins are due to be deployed onto 10,000 workstations. Our customer wants to keep the certificate used by the thick client in the central data store so that they don't need to worry about re-issuing the certificate (current re-issue cycle takes about 3 months) and also have the opportunity to authorise the use of the certificate. The proposed architecture offers a form of shared secret / authentication between the central data store and the TIBCO services. Whilst I don’t necessarily agree with the proposed architecture our team is not able to change it and must work with what’s been provided. Basically our client wants us to build into our WPF plug-ins a mechanism which retrieves the certificate from the central data store (which will be allowed or denied based on roles in that data store) into memory then use the certificate for creating the SSL connection to the TIBCO services. No use of the local machine's certificate store is allowed and the in memory version is to be discarded at the end of each session. So the question is does anyone know if it is possible to pass an in-memory certificate to a WCF (.NET 3.5) service for SSL transport level encryption? Note: I had asked a similar question (here) but have since deleted it and re-asked it with more information.

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• Making .NET assembly COM-visible and working for VB5

  - by Cyberherbalist

  I have an assembly which I have managed to make visible to VB6 and it works, but having a problem accomplishing the same thing with VB5. For VB6, I have built the assembly, made it COM-visible, registered it as a COM object etc., and the assembly shows in VB6's References list, and allows me to use it successfully. The Object Browser also shows the method in the assy. I copied the assembly and its TLB to a virtual workstation used for VB5 development, and ran Regasm, apparently successfully: C:\>C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727 \regasm arserviceinterface.dll /tlb:arserviceinterface.tlb Microsoft (R) .NET Framework Assembly Registration Utility 2.0.50727.3053 Copyright (C) Microsoft Corporation 1998-2004. All rights reserved. Assembly exported to 'C:\Projects\AR\3rd Party\ARService\arserviceinterface.tlb' , and the type library was registered successfully Note that the virtual W/S is Win2k and does not have .NET Fx 3.5 on it, just 2.0. The assembly shows up in the References that can be selected in VB5, but the method of the assembly doesn't show up in the Object Browser, and it is generally unusable. Either there is a step to do that I haven't done, or VB5 doesn't know how to use such a COM object. Note that the VB5 setup is on a virtual workstation, not the same workstation that VB6 is installed on. Any ideas? One thing that occurred to me is that I might need to generate and use a strong name on the workstation in question, but...

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• Debugging NSoperation BAD ACCESS within graphics context

  - by Joe

  I tried everything to debug this one but I can't get to the bottom of it. This code lives in a subclass of NSOperation which is processed from a queue: (borders is an ivar NSArray containing 5 UIimage objects) NSMutableArray *images = [[NSMutableArray alloc] init]; for (unsigned i = 0; i < 5; i++) { CGSize size = CGSizeMake(60, 60); UIGraphicsBeginImageContext(size); CGPoint thumbPoint = CGPointMake(6, 6); [controller.image drawAtPoint:thumbPoint]; CGPoint borderPoint = CGPointMake(0, 0); [[borders objectAtIndex:i] drawAtPoint:borderPoint]; [images addObject:UIGraphicsGetImageFromCurrentImageContext()]; UIGraphicsEndImageContext(); } [images release]; The code works fine most of the time but when I push the iphone by access subviews and pressing lots of buttons on the UI I either get this exception which is trapped by the operation: Exception Load view: *** -[NSCFArray insertObject:atIndex:]: attempt to insert nil or I get this: Program received signal: “EXC_BAD_ACCESS”. The exception is caused because UIGraphicsGetImageFromCurrentImageContext() return nil. I don't know how to debug the EXC_BAD_ACCESS but I'm guessing that this error (in fact both of these errors) is caused by low memory. The debugger stops at the line: [controller.image drawAtPoint:thumbPoint]; As I mentioned I've trapped the exception so I can live with that but the EXC_BAD_ACCESS is more serious. IF this is memory related how can I tell and is it possible to increase the memory available to NSOperation?

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• How to export Configuration of each IIS 6 Web Site using WMI

  - by Diego

  Hi all, I need to export the WebSite Configuration (MetaBase) from IIS6 for a whole server, but I need each web site configuration to be saved separately. The result should be the same that can be obtained by right clicking on each Web Site in IIS Snap-in and selecting All Tasks-Save Configuration to a File. My idea is quite simple: 1- Using WMI, retrieve a list of Web Sites. 2- Also via WMI, export each configuration to a file having the same name of the Web Site. However, I'm having some difficulties, mainly due to the complexity of WMI and, in my opinion, the poor documentation of its classes. At the moment I found out how to enumerate Virtual Directories, but not Web Sites; while it's true that this method returns Web Sites as well, I can't see how to identify them among other virtual folders (a Web Site has different properties, which are not returned in the Virtual Directory Object), and I can't find the Web Site Description property, which I'd like to use to name the exported file. I thought about a workaround for all the above issues, but it would be more a hack than a real solution... Any help if appreciated. Thanks.

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• How to query collections in NHibernate

  - by user305813

  Hi, I have a class: public class User { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual IDictionary<string, string> Attributes { get; set; } } and a mapping file: <class name="User" table="Users"> <id name="Id"> <generator class="hilo"/> </id> <property name="Name"/> <map name="Attributes" table="UserAttributes"> <key column="UserId"/> <index column="AttributeName" type="System.String"/> <element column="Attributevalue" type="System.String"/> </map> </class> So now I can add many attributes and values to a User. How can I query those attributes so I can get ie. Get all the users where attributename is "Age" and attribute value is "20" ? I don't want to do this in foreach because I may have millions of users each having its unique attributes. Please help

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• How can i ignore map property in NHibernate with setter

  - by Emilio Montes

  i need ignore map property with setter in NHibernate, because the relationship between entities is required. this is my simple model public class Person { public virtual Guid PersonId { get; set; } public virtual string FirstName { get; set; } public virtual string SecondName { get; set; } //this is the property that do not want to map public Credential Credential { get; set; } } public class Credential { public string CodeAccess { get; set; } public bool EsPremium { get; set; } } public sealed class PersonMap : ClassMapping<Person> { public PersonMap() { Table("Person"); Cache(x => x.Usage(CacheUsage.ReadWrite)); Id(x => x.Id, m => { m.Generator(Generators.GuidComb); m.Column("PersonId"); }); Property(x => x.FirstName, map => { map.NotNullable(true); map.Length(255); }); Property(x => x.SecondName, map => { map.NotNullable(true); map.Length(255); }); } } I know that if I leave the property Credential {get;} I was not going to take the map of NHibernate, but I need to set the value. Thanks in advance.

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• Why not lump all service classes into a Factory method (instead of injecting interfaces)?

  - by Andrew

  We are building an ASP.NET project, and encapsulating all of our business logic in service classes. Some is in the domain objects, but generally those are rather anemic (due to the ORM we are using, that won't change). To better enable unit testing, we define interfaces for each service and utilize D.I.. E.g. here are a couple of the interfaces: IEmployeeService IDepartmentService IOrderService ... All of the methods in these services are basically groups of tasks, and the classes contain no private member variables (other than references to the dependent services). Before we worried about Unit Testing, we'd just declare all these classes as static and have them call each other directly. Now we'll set up the class like this if the service depends on other services: public EmployeeService : IEmployeeService { private readonly IOrderService _orderSvc; private readonly IDepartmentService _deptSvc; private readonly IEmployeeRepository _empRep; public EmployeeService(IOrderService orderSvc , IDepartmentService deptSvc , IEmployeeRepository empRep) { _orderSvc = orderSvc; _deptSvc = deptSvc; _empRep = empRep; } //methods down here } This really isn't usually a problem, but I wonder why not set up a factory class that we pass around instead? i.e. public ServiceFactory { virtual IEmployeeService GetEmployeeService(); virtual IDepartmentService GetDepartmentService(); virtual IOrderService GetOrderService(); } Then instead of calling: _orderSvc.CalcOrderTotal(orderId) we'd call _svcFactory.GetOrderService.CalcOrderTotal(orderid) What's the downfall of this method? It's still testable, it still allows us to use D.I. (and handle external dependencies like database contexts and e-mail senders via D.I. within and outside the factory), and it eliminates a lot of D.I. setup and consolidates dependencies more. Thanks for your thoughts!

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• Multithreading and Interrupts

  - by Nicholas Flynt

  I'm doing some work on the input buffers for my kernel, and I had some questions. On Dual Core machines, I know that more than one "process" can be running simultaneously. What I don't know is how the OS and the individual programs work to protect collisions in data. There are two things I'd like to know on this topic: (1) Where do interrupts occur? Are they guaranteed to occur on one core and not the other, and could this be used to make sure that real-time operations on one core were not interrupted by, say, file IO which could be handled on the other core? (I'd logically assume that the interrupts would happen on the 1st core, but is that always true, and how would you tell? Or perhaps does each core have its own settings for interrupts? Wouldn't that lead to a scenario where each core could react simultaneously to the same interrupt, possibly in different ways?) (2) How does the dual core processor handle opcode memory collision? If one core is reading an address in memory at exactly the same time that another core is writing to that same address in memory, what happens? Is an exception thrown, or is a value read? (I'd assume the write would work either way.) If a value is read, is it guaranteed to be either the old or new value at the time of the collision? I understand that programs should ideally be written to avoid these kinds of complications, but the OS certainly can't expect that, and will need to be able to handle such events without choking on itself.

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• Delphi, PGDac vs Zeos, Fetch, Lookup?

  - by durumdara

  Hi! I used Zeos to test to know: is ZTable uses fetch technics, or not? May in the future we migrate our lesser system to PGSQL, and this used now "Table" components (as BDE, but it have an SQL-like server). These tables use real cursors, a "Window" with N record, so lookup is very fast, because the Locate/Lookup is started on server, and only these N records are refreshed, no matter, how many records in the lookup table. PGSQL uses fetch technics as I know, and I tested it with a table (id int, name varchar(100)), and 1 million records. (I also trying this with mysql). The adapter is Zeos. ID, sec to find, allocated memory in bytes on client. MySQL 500000 2,761 113 196 344 1000000 3,214 225 471 232 313800 0,437 225 471 232 328066 0,468 225 471 232 276374 0,390 225 471 232 905984 1,264 225 471 232 260253 0,359 225 471 232 PGSQL 500000 3,042 113 188 184 1000000 3,744 225 463 064 313800 0,436 225 463 064 328066 0,452 225 463 064 276374 0,375 225 463 064 905984 1,295 225 463 064 260253 0,359 225 463 064 142023 0,203 225 463 064 As you see the records are fetched locally, this cause the 225 MB usage, and searches are slow a little, based where is the record we must find. I want to ask more things: a.) Is PGDAC have some technics to we can use the lookups without pay the fetch with memory and secs? b.) Or is PG ODBC driver can help in this problem with ADO? (As I know ADO can use server side cursors)? c.) Have anybody some experience with lookup tables, and performance? Is this critical question or it is not? (With client memory usage too). d.) If no chance to avoid fetch hell with lookups, what we can do? Server Side Joins, and unique code for Lookup field changing without real Lookup? Thanks for your help: dd

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• Most efficient way to send images across processes

  - by Heinrich Ulbricht

  Goal Pass images generated by one process efficiently and at very high speed to another process. The two processes run on the same machine and on the same desktop. The operating system may be WinXP, Vista and Win7. Detailled description The first process is solely for controlling the communication with a device which produces the images. These images are about 500x300px in size and may be updated up to several hundred times per second. The second process needs these images to display them. The first process uses a third party API to paint the images from the device to a HDC. This HDC has to be provided by me. Note: There is already a connection open between the two processes. They are communicating via anonymous pipes and share memory mapped file views. Thoughts How would I achieve this goal with as little work as possible? And I mean both work for me and the computer. I am using Delphi, so maybe there is some component available for doing this? I think I could always paint to any image component's HDC, save the content to memory stream, copy the contents via the memory mapped file, unpack it on the other side and paint it there to the destination HDC. I also read about a IPicture interface which can be used to marshall images. What are your ideas? I appreciate every thought on this!

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• Swig: No Constructor defined

  - by wheaties

  I added %allowexcept to my *.i file when building a Python <-- C++ bridge using Swig. Then I removed that preprocessing directive. Now I can't get the Python produced code to recognize the constructor of a C++ class. Here's the class file: #include <exception> class Swig_Foo{ public: Swig_Foo(){} virtual ~Swig_Foo(){} virtual getInt() =0; virtual throwException() { throw std::exception(); } }; And here's the code Swig produces from it: class Swig_Foo: __swig_setmethods__ = {} __setattr__ = lambda self, name, value: _swig_setattr(self, Swig_Foo, name, value) __swig_getmethods__ = {} __getattr__ = lambda self, name: _swig_getattr(self, Swig_Foo, name) def __init__(self): raise AttributeError, "No constructor defined" __repr__ = _swig_repr __swig_destroy__ = _foo.delete_Swig_Foo __del__ = lambda self : None; def getInt(*args): return apply(_foo.Swig_Foo_getInt, args) def throwOut(*args): return apply(_foo.Swig_Foo_throwOut, args) Swig_Foo_swigregister = _foo.Swig_Foo_swigregister Swig_Foo_swigregister(Swig_Foo) The problem is the def __init__self): raise AttributeError, "No constructor defined" portion. It never did this before I added the %allowexception and now that I've removed it, I can't get it to create a real constructor. All the other classes have actual constructors. Quite baffled. Anyone know how I can get it to stop doing this?

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• Does NHibernate LINQ support ToLower() in Where() clauses?

  - by Daniel T.

  I have an entity and its mapping: public class Test { public virtual int Id { get; set; } public virtual string Name { get; set; } public virtual string Description { get; set; } } public class TestMap : EntityMap<Test> { public TestMap() { Id(x => x.Id); Map(x => x.Name); Map(x => x.Description); } } I'm trying to run a query on it (to grab it out of the database): var keyword = "test" // this is coming in from the user keyword = keyword.ToLower(); // convert it to all lower-case var results = session.Linq<Test> .Where(x => x.Name.ToLower().Contains(keyword)); results.Count(); // execute the query However, whenever I run this query, I get the following exception: Index was out of range. Must be non-negative and less than the size of the collection. Parameter name: index Am I right when I say that, currently, Linq to NHibernate does not support ToLower()? And if so, is there an alternative that allows me to search for a string in the middle of another string that Linq to NHibernate is compatible with? For example, if the user searches for kap, I need it to match Kapiolani, Makapuu, and Lapkap.

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