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  • Mapping One-to-One subclass in Fluent NHibernate

    - by Mike C.
    I have the following database structure: Event table Id - Guid (PK) Name - NVarChar Description - NVarChar SpecialEvent table Id - Guid (PK) StartDate - DateTime EndDate - DateTime I have an abstract Event class, and a SpecialEvent class that inherits from it. Eventually I will have a RecurringEvent class which will inherit from the Event class also. I'd like to map the SpecialEvent class while preserving a one-to-one relationship mapped with the Ids, if possible. Can anybody point me in the correct direction? Thanks!

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  • thread management in nbody code of cuda-sdk

    - by xnov
    When I read the nbody code in Cuda-SDK, I went through some lines in the code and I found that it is a little bit different than their paper in GPUGems3 "Fast N-Body Simulation with CUDA". My questions are: First, why the blockIdx.x is still involved in loading memory from global to share memory as written in the following code? for (int tile = blockIdx.y; tile < numTiles + blockIdx.y; tile++) { sharedPos[threadIdx.x+blockDim.x*threadIdx.y] = multithreadBodies ? positions[WRAP(blockIdx.x + q * tile + threadIdx.y, gridDim.x) * p + threadIdx.x] : //this line positions[WRAP(blockIdx.x + tile, gridDim.x) * p + threadIdx.x]; //this line __syncthreads(); // This is the "tile_calculation" function from the GPUG3 article. acc = gravitation(bodyPos, acc); __syncthreads(); } isn't it supposed to be like this according to paper? I wonder why sharedPos[threadIdx.x+blockDim.x*threadIdx.y] = multithreadBodies ? positions[WRAP(q * tile + threadIdx.y, gridDim.x) * p + threadIdx.x] : positions[WRAP(tile, gridDim.x) * p + threadIdx.x]; Second, in the multiple threads per body why the threadIdx.x is still involved? Isn't it supposed to be a fix value or not involving at all because the sum only due to threadIdx.y if (multithreadBodies) { SX_SUM(threadIdx.x, threadIdx.y).x = acc.x; //this line SX_SUM(threadIdx.x, threadIdx.y).y = acc.y; //this line SX_SUM(threadIdx.x, threadIdx.y).z = acc.z; //this line __syncthreads(); // Save the result in global memory for the integration step if (threadIdx.y == 0) { for (int i = 1; i < blockDim.y; i++) { acc.x += SX_SUM(threadIdx.x,i).x; //this line acc.y += SX_SUM(threadIdx.x,i).y; //this line acc.z += SX_SUM(threadIdx.x,i).z; //this line } } } Can anyone explain this to me? Is it some kind of optimization for faster code?

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  • Maximum executable size on the iPhone?

    - by Sirp
    Is there a maximum size of executables or executables + shared objects on the iPhone? I've been developing an app that has been crashing on startup or early in execution with SIGSYS. Removing code from the program has helped, though structuring data so the code is simply not executed does not. This could be memory corruption, of some kind, however when I compiled with -Os rather than -O2 or -O3 the size of my executable goes down from 5.15MB to 3.60MB and the application runs perfectly. I also have a bunch of libraries I use, of course. I'm wondering, is there a limit on the size of executable code on the iPhone? Or am I just 'getting lucky' and masking memory corruption when I use -Os?

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  • How to write a datatable to excel work book at client side

    - by senthilkumar
    Hi Guys Currently i am doing one project in that we need to generate report from database. Since my server memory is too low im getting 'Out of Memory' Exception when im writing it at serverside and also when i write directly to a excel file using http header as excel file im not able to create multiple sheets since my database table is huge more than 65536 rows. I saw many solution using a third party tool but i cant use those into mine..If anyone already worked on this please give me some direction. Also i tried using javascript but for that i need to use datagrid at server side?? but in my project i m not allowed to use like this.

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  • Advice on "Invalid Pointer Operation" when using complex records

    - by Xaz
    Env: Delphi 2007 <JustificationI tend to use complex records quite frequently as they offer almost all of the advantages of classes but with much simpler handling.</Justification Anyhoo, one particularly complex record I have just implemented is trashing memory (later leading to an "Invalid Pointer Operation" error). This is an example of the memory trashing code: sSignature := gProfiles.Profile[_stPrimary].Signature.Formatted(True); On the second time i call it i get "Invalid Pointer Operation" It works OK if i call it like this: AProfile := gProfiles.Profile[_stPrimary]; ASignature := AProfile.Signature; sSignature := ASignature.Formatted(True); Background Code: gProfiles: TProfiles; TProfiles = Record private FPrimaryProfileID: Integer; FCachedProfile: TProfile; ... public < much code removed > property Profile[ProfileType: TProfileType]: TProfile Read GetProfile; end; function TProfiles.GetProfile(ProfileType: TProfileType): TProfile; begin case ProfileType of _stPrimary : Result := ProfileByID(FPrimaryProfileID); ... end; end; function TProfiles.ProfileByID(iID: Integer): TProfile; begin <snip> if LoadProfileOfID(iID, FCachedProfile) then begin Result := FCachedProfile; end else ... end; TProfile = Record private ... public ... Signature: TSignature; ... end; TSignature = Record private public PlainTextFormat : string; HTMLFormat : string; // The text to insert into a message when using this profile function Formatted(bHTML: boolean): string; end; function TSignature.Formatted(bHTML: boolean): string; begin if bHTML then result := HTMLFormat else result := PlainTextFormat; < SNIP MUCH CODE > end; OK, so I have a record within a record within a record, which is approaching Inception level confusion and I'm the first to admit is not really a good model. Clearly i am going to have to restructure it. What I would like from you gurus is a better understanding of why it is trashing the memory (something to do with the string object that is created then freed...) so that i can avoid making these kinds of errors in future. Thanks

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  • Why do you have to mark a class with the attribute [serializable] ?

    - by Blankman
    Seeing as you can convert any document to a byte array and save it to disk, and then rebuild the file to its original form (as long as you have meta data for its filename etc.). Why do you have to mark a class with [Serializable] etc? Is that just the same idea, "meta data" type information so when you cast the object to its class things are mapped properly?

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  • Unable to login to SQL Server + SQL Server Authentication + Error: 18456

    - by Nev_Rahd
    Hello I have created login account on my localhost\sql2008 Server (Eg. User123) Mapped to Database (default) Authentication Mode on SQL Server is set to both (Windows and SQL) But login to SQL Server fails with following message (for User123) Note: Have checked mutliple time that UserName / Password are typed in correctly Error Details: Login failed for user 'User123' (Net.SqlClient Data Provider) Server Name : localhost\sql2008 Error Number: 18456 Severity : 14 State : 1 Line Number : 65536 any help on this please. Thanks

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  • C++ conditional compilation

    - by Shaown
    I have the following code snippet #ifdef DO_LOG #define log(p) record(p) #else #define log(p) #endif void record(char *data){ ..... ..... } Now if I call log("hello world") in my code and DO_LOG isn't defined, will the line be compiled, in other words will it eat up the memory for the string "hello world"? P.S. There are a lot of record calls in the program and it is memory sensitive, so is there any other way to conditionally compile so that it only depends on the #define DO_LOG? Thanks in advance.

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  • [N]Hibernate: view-like fetching properties of associated class

    - by chiccodoro
    (Felt quite helpless in formulating an appropriate title...) In my C# app I display a list of "A" objects, along with some properties of their associated "B" objects and properties of B's associated "C" objects: A.Name B.Name B.SomeValue C.Name Foo Bar 123 HelloWorld Bar Hello 432 World ... To clarify: A has an FK to B, B has an FK to C. (Such as, e.g. BankAccount - Person - Company). I have tried two approaches to load these properties from the database (using NHibernate): A fast approach and a clean approach. My eventual question is how to do a fast & clean approach. Fast approach: Define a view in the database which joins A, B, C and provides all these fields. In the A class, define properties "BName", "BSomeValue", "CName" Define a hibernate mapping between A and the View, whereas the needed B and C properties are mapped with update="false" insert="false" and do actually stem from B and C tables, but Hibernate is not aware of that since it uses the view. This way, the listing only loads one object per "A" record, which is quite fast. If the code tries to access the actual associated property, "A.B", I issue another HQL query to get B, set the property and update the faked BName and BSomeValue properties as well. Clean approach: There is no view. Class A is mapped to table A, B to B, C to C. When loading the list of A, I do a double left-join-fetch to get B and C as well: from A a left join fetch a.B left join fetch a.B.C B.Name, B.SomeValue and C.Name are accessed through the eagerly loaded associations. The disadvantage of this approach is that it gets slower and takes more memory, since it needs to created and map 3 objects per "A" record: An A, B, and C object each. Fast and clean approach: I feel somehow uncomfortable using a database view that hides a join and treat that in NHibernate as if it was a table. So I would like to do something like: Have no views in the database. Declare properties "BName", "BSomeValue", "CName" in class "A". Define the mapping for A such that NHibernate fetches A and these properties together using a join SQL query as a database view would do. The mapping should still allow for defining lazy many-to-one associations for getting A.B.C My questions: Is this possible? Is it [un]artful? Is there a better way?

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  • C++'s std::string pools, debug builds? std::string and valgrind problems

    - by Den.Jekk
    Hello, I have a problem with many valgrind warnings about possible memory leaks in std::string, like this one: 120 bytes in 4 blocks are possibly lost in loss record 4,192 of 4,687 at 0x4A06819: operator new(unsigned long) (vg_replace_malloc.c:230) by 0x383B89B8B0: std::string::_Rep::_S_create(unsigned long, unsigned long, std::allocator<char> const&) (in /usr/lib64/libstdc++.so.6.0.8) by 0x383B89C3B4: (within /usr/lib64/libstdc++.so.6.0.8) by 0x383B89C4A9: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, unsigned long, std::allocator<char> const&) (in /usr/lib64/libstdc++.so.6.0.8) I'm wondering: does std::string (GCC 4.1.2) use any memory pools? if so, is there any way to disable the pools (in form of a debug build etc.)? Regards, Den

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  • data structure for counting frequencies in a database table-like format

    - by user373312
    i was wondering if there is a data structure optimized to count frequencies against data that is stored in a database table-like format. for example, the data comes in a (comma) delimited format below. col1, col2, col3 x, a, green x, b, blue ... y, c, green now i simply want to count the frequency of col1=x or col1=x and col2=green. i have been storing the data in a database table, but in my profiling and from empirical observation, database connection is the bottle-neck. i have tried using in-memory database solutions too, and that works quite well; the only problem is memory requirements and quirky init/destroy calls. also, i work mainly with java, but have experience with .net, and was wondering if there was any api to work with "tabular" data in a linq way using java. any help is appreciated.

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  • Type Declaration - Pointer Asterisk Position

    - by sahs
    Hello, in C++, the following means "allocate memory for an int pointer": int* number; So, the asterisk is part of the variable type; without it, that would mean something else (that's why I usually don't separate the asterisk from the variable type). Then what is the reason the asterisk is considered something else, instead of being part of the type? For example, it seems better, if the following meant "allocate memory for two int pointers": int* number1, number2; Am I wrong?

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  • Efficient alternatives to merge for larger data.frames R

    - by Etienne Low-Décarie
    I am looking for an efficient (both computer resource wise and learning/implementation wise) method to merge two larger (size1 million / 300 KB RData file) data frames. "merge" in base R and "join" in plyr appear to use up all my memory effectively crashing my system. Example load test data frame and try test.merged<-merge(test, test) or test.merged<-join(test, test, type="all") - The following post provides a list of merge and alternatives: How to join data frames in R (inner, outer, left, right)? The following allows object size inspection: https://heuristically.wordpress.com/2010/01/04/r-memory-usage-statistics-variable/ Data produced by anonym

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  • What are the pros and cons of using manual list iteration vs recursion through fail

    - by magus
    I come up against this all the time, and I'm never sure which way to attack it. Below are two methods for processing some season facts. What I'm trying to work out is whether to use method 1 or 2, and what are the pros and cons of each, especially large amounts of facts. methodone seems wasteful since the facts are available, why bother building a list of them (especially a large list). This must have memory implications too if the list is large enough ? And it doesn't take advantage of Prolog's natural backtracking feature. methodtwo takes advantage of backtracking to do the recursion for me, and I would guess would be much more memory efficient, but is it good programming practice generally to do this? It's arguably uglier to follow, and might there be any other side effects? One problem I can see is that each time fail is called, we lose the ability to pass anything back to the calling predicate, eg. if it was methodtwo(SeasonResults), since we continually fail the predicate on purpose. So methodtwo would need to assert facts to store state. Presumably(?) method 2 would be faster as it has no (large) list processing to do? I could imagine that if I had a list, then methodone would be the way to go.. or is that always true? Might it make sense in any conditions to assert the list to facts using methodone then process them using method two? Complete madness? But then again, I read that asserting facts is a very 'expensive' business, so list handling might be the way to go, even for large lists? Any thoughts? Or is it sometimes better to use one and not the other, depending on (what) situation? eg. for memory optimisation, use method 2, including asserting facts and, for speed use method 1? season(spring). season(summer). season(autumn). season(winter). % Season handling showseason(Season) :- atom_length(Season, LenSeason), write('Season Length is '), write(LenSeason), nl. % ------------------------------------------------------------- % Method 1 - Findall facts/iterate through the list and process each %-------------------------------------------------------------- % Iterate manually through a season list lenseason([]). lenseason([Season|MoreSeasons]) :- showseason(Season), lenseason(MoreSeasons). % Findall to build a list then iterate until all done methodone :- findall(Season, season(Season), AllSeasons), lenseason(AllSeasons), write('Done'). % ------------------------------------------------------------- % Method 2 - Use fail to force recursion %-------------------------------------------------------------- methodtwo :- % Get one season and show it season(Season), showseason(Season), % Force prolog to backtrack to find another season fail. % No more seasons, we have finished methodtwo :- write('Done').

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  • How can I position QDockWidgets as the screen shot shows using code?

    - by Nathan
    I want a Qt window to come up with the following arrangement of dock widgets on the right. Qt allows you to provide an argument to the addDockWidget method of QMainWindow to specify the position (top, bottom, left or right) but apparently not how two QDockWidgets placed on the same side will be arranged. Here is the code that adds the dock widgets. this uses PyQt4 but it should be the same for Qt with C++ self.memUseGraph = mem_use_widget(self) self.memUseDock = QDockWidget("Memory Usage") self.memUseDock.setObjectName("Memory Usage") self.memUseDock.setWidget(self.memUseGraph) self.addDockWidget(Qt.DockWidgetArea(Qt.RightDockWidgetArea),self.memUseDock) self.diskUsageGraph = disk_usage_widget(self) self.diskUsageDock = QDockWidget("Disk Usage") self.diskUsageDock.setObjectName("Disk Usage") self.diskUsageDock.setWidget(self.diskUsageGraph) self.addDockWidget(Qt.DockWidgetArea(Qt.RightDockWidgetArea),self.diskUsageDock) When this code is used to add both of them to the right side, one is above the other, not like the screen shot I made. The way I made that shot was to drag them there with the mouse after starting the program, but I need it to start that way.

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  • Can my app arrange a gdb breakpoint or watch?

    - by Larry Gritz
    Is there a way for my code to be instrumented to insert a break point or watch on a memory location that will be honored by gdb? (And presumably have no effect when gdb is not attached.) I know how to do such things as gdb commands within the gdb session, but for certain types of debugging it would be really handy to do it "programmatically", if you know what I mean -- for example, the bug only happens with a particular circumstance, not any of the first 11,024 times the crashing routine is called, or the first 43,028,503 times that memory location is modified, so setting a simple break point on the routine or watch point on the variable is not helpful -- it's all false positives. I'm concerned mostly about Linux, but curious about if similar solutions exist for OS X (or Windows, though obviously not with gdb).

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  • C++: Why don't I need to check if references are invalid/null?

    - by jbu
    Hi all, Reading http://www.cprogramming.com/tutorial/references.html, it says: In general, references should always be valid because you must always initialize a reference. This means that barring some bizarre circumstances (see below), you can be certain that using a reference is just like using a plain old non-reference variable. You don't need to check to make sure that a reference isn't pointing to NULL, and you won't get bitten by an uninitialized reference that you forgot to allocate memory for. My question is how do I know that the object's memory hasn't been freed/deleted AFTER you've initialized the reference. What it comes down to is that I can't take this advice on faith and I need a better explanation. Can anyone shed some light? Thanks, jbu

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  • Sound Manager Classes for Windows (C# or C++ .Net 2.0)

    - by Yakov
    Hi guys! I need some classes for playing short wav sounds, this classes would load this wav files into memory when an instance created, play sounds in background when needed, release this wav files from memory when an instance disposed. How can I do this on C# for windows (.Net 2.0)? (Win API's sndPlaySound, OpenAL or may be any wrapper) Ideally I would love to find an exist solution that simple and able to solve my task. Do you know any solutions for this issue? Thankx for your time.

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  • What is faster: multiple `send`s or using buffering?

    - by dauerbaustelle
    I'm playing around with sockets in C/Python and I wonder what is the most efficient way to send headers from a Python dictionary to the client socket. My ideas: use a send call for every header. Pros: No memory allocation needed. Cons: many send calls -- probably error prone; error management should be rather complicated use a buffer. Pros: one send call, error checking a lot easier. Cons: Need a buffer :-) malloc/realloc should be rather slow and using a (too) big buffer to avoid realloc calls wastes memory. Any tips for me? Thanks :-)

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  • How do I map a one-to-one value type association in an joined-subclass?

    - by David Rubin
    I've got a class hierarchy mapped using table-per-subclass, and it's been working out great: class BasicReport { ... } class SpecificReport : BasicReport { ... } With mappings: <class name="BasicReport" table="reports"> <id name="Id" column="id">...</id> <!-- some common properties --> </class> <joined-subclass name="SpecificReport" table="specificReports" extends="BasicReport"> <key column="id"/> <!-- some special properties --> </joined-subclass> So far, so good. The problem I'm struggling with is how to add a property to one of my subclasses that's both a value type for which I have an IUserType implemented and also mapped via an association: class OtherReport : BasicReport { public SpecialValue V { get; set; } } class SpecialValueUserType : IUserType { ... } What I'd like to do is: <joined-subclass name="OtherReport" table="otherReports" extends="BasicReport"> <key column="id"/> <join table="rptValues" fetch="join"> <key column="rptId"/> <property name="V" column="value" type="SpecialValueUserType"/> </join> </joined-subclass> This accurately reflects the intent, and the pre-existing database schema I'm tied to: the SpecialValue instance is a property of the OtherReport, but is stored in a separate table ("rptValues"). Unfortunately, it seems as though I can't do this, because <join> elements can't be used in <joined-subclass> mappings. <one-to-one> would require creating a class mapping for SpecialValue, which doesn't make any sense given that SpecialValue is just a meaningful scalar. So what can I do? Do I have any options? Right now I'm playing a game with sets: class OtherReport : BasicReport { public SpecialValue V { get { return _values.Count() > 0 ? _values.First() : null; } set { _values.Clear(); _values.Add(value); } } private ICollection<SpecialValue> _values; } With mapping: <joined-subclass name="OtherReport" table="otherReports" extends="BasicReport"> <key column="id"/> <set name="_values" access="field" table="rptValues" cascade="all-delete-orphan"> <key column="rptId" /> <element column="value" type="SpecialValueUserType"/> </set> </joined-subclass> Thanks in advance for the help! I've been banging my head into my desk for several days now.

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  • python dictionary with constant value-type

    - by s.kap
    hi there, I bumped into a case where I need a big (=huge) python dictionary, which turned to be quite memory-consuming. However, since all of the values are of a single type (long) - as well as the keys, I figured I can use python (or numpy, doesn't really matter) array for the values ; and wrap the needed interface (in: x ; out: d[x]) with an object which actually uses these arrays for the keys and values storage. I can use a index-conversion object (input -- index, of 1..n, where n is the different-values counter), and return array[index]. I can elaborate on some techniques of how to implement such an indexing-methods with reasonable memory requirement, it works and even pretty good. However, I wonder if there is such a data-structure-object already exists (in python, or wrapped to python from C/++), in any package (I checked collections, and some Google searches). Any comment will be welcome, thanks.

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