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  • File Access problems with SLES 10 SP2 OES2 SP1

    - by Blackhawk131
    We have identified a couple of repeatable, demonstrable scenarios with unexplained rejected folder access on our servers for Mac users. Hopefully, this can be presented to Novell for a solution. What we did to demonstrate scenario 1; 1. setup a PC and Mac side-by-side 2. login to our server and open up to a central location on both Mac and PC 3. on the PC in that central location create a folder 4. on the Mac in that central location drag the created folder to the Mac desktop, this should work fine, no problem 5. on the PC rename that folder 6. on the Mac drag a file to that renamed folder, this should error with the following message; a. You cannot copy some of these items to the destination because their names are too long for the destination. Do you want to skip copying these items and continue copying the other items? b. Select skip, response is the filename is copied to the location with zero or small byte size. Try opening it and you get file is corrupted error message. What we did to demonstrate scenario 2; 1. setup a PC and Mac side-by-side 2. login to our server and open up to a central location on both Mac and PC 3. on the PC in that central location create a folder then create a subfolder 4. copy some content into the subfolder 5. on the Mac in that central location drag the created top level folder to the Mac desktop, this should work fine, no problem 6. on the PC rename that subfolder 7. on the Mac drag that top level folder to the Mac desktop, this should error on the Mac with the following; a. The operation cannot be completed because you do not have sufficient privileges for b. The operation cannot be completed because you do not have sufficient privileges for 8. on the Mac, if you open that subfolder you can see the file copied in step 4 above but, you can not open that file, you get the following message if you try; a. There was an error opening this document. You do not have permission to open this file. 9. on the PC drag some content into the top level folder 10. on the Mac you can open that file directly from the server or copy it locally, no problem, however-the subfolder is still corrupted or locked, whichever 11. on the PC rename the top level folder 12. on the Mac that same file just opened in step 10 above is now not accessible, get the following message; a. The document could not be opened. I have observed some variances in the above. For instance, a change on the PC side may take a moment before you can observer or act on the Mac side - kind of like the server is slow to respond. Also, the error message may vary. However, the key is once a folder, or subfolder, gets renamed by a PC, Mac problems commence. The solution is to create a new folder from a PC and copy the contents of the corrupted folder to the new folder and not rename the folder name. This has to be done on a PC because the corrupted folder is not accessible by a Mac user. Another problem that dovetails with the above is that we know certain characters are not allowed for PC folder or filenames. If a Mac user creates a folder with a slash in the file name, from the PC the user does not see that slash in the name. As soon as the PC user copies a file to that folder, the Mac user is locked from that folder. Will get the following error message; - Sorry, the operation could not be completed because an unexpected error occurred. - (Error code - 50) In addition to the above mentioned character issue with folders, the problem is more evil with filenames. If, for example, you create a file with a slash in the filename on a Mac and copy it to the server you will get the following error message; - You cannot copy some of these items to the destination because their names are too long for the destination. Do you want to skip copying these items and continue copying the other items? Select either Stop or Skip buttons. It does not matter which button is selected. The file name gets copied to the destination location at a reduced size. Depending on the file type, the icon associated with the file may or may not be present. Furthermore, if you open that file on the server you will get the following message; - Couldnt open the file. It may be corrupt or a file format that doesnt recognize. From the users perspective, if they are not observant of the icon or file size, they may disregard the error message and think their file has copied as intended. Only later do they discover the file is corrupt if they open that file. I want to make a note on this problem. It is the PC causing the issue. You can change folder and file names all day on a MAC and you don't have a problem as long as a character is not the issue. Once you change the file name or folder name from a PC the entire folder structure from that level down is corrupted. But it has to be resolved from a PC by creating a new folder and copying the contents to the new folder like stated above. Is something not configured correctly? SUSE Linux Enterprise Server 10 (x86_64) VERSION = 10 PATCHLEVEL = 2 LSB_VERSION="core-2.0-noarch:core-3.0-noarch:core-2.0-x86_64:core-3.0-x86_64" Novell Open Enterprise Server 2.0.1 (x86_64) VERSION = 2.0.1 PATCHLEVEL = 1 BUILD Note: We use Novell clients on all windows systems to connect to the servers for file access and network storage. We use AFP to allow OSx systems to connect to servers.

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  • Windows 7 explorer always crashes, opens small "Personalized Settings" window

    - by Ian Sellar
    My Windows 7 desktop PC, built by me, started acting very weird in the last couple of days. I use it quite often, about half of the time through TeamViewer. Explorer would crash and restart randomly, almost always through TeamViewer. This made me suspect that TeamViewer was the problem but I have reproduced it with and without TeamViewer several times. The only way I can seem to get the problem not to occur is by booting into Safe Mode. I have used CCleaner and Malwarebytes to make sure it wasn't a registry error or malware causing the problem, and I have tried the fix in the seemly related issue here as well every other fix I have found online including removing security updates KB980408 and KB2926765 as well as using "sfc /scannow" and a bunch of other things I can't remember. More recently when I try to start explorer it is popping up a small window that says "Personalized Settings" on the top, but is completely empty and crashes instantly. The only way I can get it to disappear is to kill the explorer.exe process. I wish I could take a screenshot but I can't seem to open paint or even find the exe. I have tried restarting it, I have tried starting it while the personalized settings window was open. I have come up with two lists of processes the first is the list of active processes when I boot into safe mode and explorer seems to work fine. The second is the list of processes that I can narrow it down to in normal boot and still replicate the problem. There is one process that I can't seem to close. NisSrv.exe which is describes as "Microsoft Network Realtime Inspection Service". When I try to close the process NisSrv.exe it says "The operation could not be completed. Access is denied." When I try to close the related service it gives the same message. Image Name PID Session Name Session# Mem Usage ========================= ======== ================ =========== ============ System Idle Process 0 Services 0 24 K System 4 Services 0 2,660 K smss.exe 304 Services 0 1,196 K csrss.exe 408 Services 0 4,156 K wininit.exe 444 Services 0 4,608 K csrss.exe 452 Console 1 8,700 K services.exe 492 Services 0 7,700 K winlogon.exe 524 Console 1 5,756 K lsass.exe 536 Services 0 10,644 K lsm.exe 544 Services 0 4,316 K svchost.exe 652 Services 0 8,976 K MsMpEng.exe 804 Services 0 40,696 K explorer.exe 1332 Console 1 85,220 K ctfmon.exe 1376 Console 1 3,680 K dllhost.exe 1624 Console 1 8,656 K chrome.exe 1408 Console 1 98,504 K WmiPrvSE.exe 2352 Services 0 6,472 K chrome.exe 1744 Console 1 65,116 K taskmgr.exe 372 Console 1 14,948 K cmd.exe 2776 Console 1 2,960 K conhost.exe 1816 Console 1 3,580 K tasklist.exe 2308 Console 1 5,868 K And the list of processes I have narrowed it down to. Image Name PID Session Name Session# Mem Usage ========================= ======== ================ =========== ============ System Idle Process 0 Services 0 24 K System 4 Services 0 2,808 K smss.exe 316 Services 0 1,216 K csrss.exe 484 Services 0 4,532 K wininit.exe 596 Services 0 4,604 K csrss.exe 604 Console 1 23,676 K services.exe 652 Services 0 11,344 K lsass.exe 668 Services 0 12,692 K lsm.exe 676 Services 0 4,464 K MsMpEng.exe 972 Services 0 68,436 K winlogon.exe 168 Console 1 7,784 K svchost.exe 496 Services 0 19,140 K NisSrv.exe 3176 Services 0 808 K svchost.exe 1684 Services 0 11,260 K taskmgr.exe 4524 Console 1 20,696 K cmd.exe 4764 Console 1 7,224 K conhost.exe 4772 Console 1 6,916 K sublime_text.exe 2340 Console 1 45,012 K dllhost.exe 4476 Console 1 8,736 K tasklist.exe 3796 Console 1 5,768 K WmiPrvSE.exe 1768 Services 0 6,344 K Here is the event data xml from event viewer for the error I am getting. <EventData> <Data>explorer.exe</Data> <Data>6.1.7601.17567</Data> <Data>4d672ee4</Data> <Data>vrfcore.dll</Data> <Data>6.3.9600.16384</Data> <Data>5215f8f5</Data> <Data>80000003</Data> <Data>0000000000003a00</Data> <Data>12e4</Data> <Data>01cfb84fa70f89dc</Data> <Data>C:\Windows\system32\explorer.exe</Data> <Data>C:\Windows\SYSTEM32\vrfcore.dll</Data> <Data>e5957093-2442-11e4-9f8a-94de806ed9cb</Data> </EventData> I was looking through the eventvwr log again and I found this, possibly related <EventData> <Data>runonce.exe</Data> <Data>6.1.7601.17514</Data> <Data>4ce7a253</Data> <Data>MSVCR100.dll</Data> <Data>10.0.40219.325</Data> <Data>4df2bcac</Data> <Data>c0000005</Data> <Data>000000000003c145</Data> <Data>670</Data> <Data>01cfb8dabbd85942</Data> <Data>C:\Windows\system32\runonce.exe</Data> <Data>C:\Windows\system32\MSVCR100.dll</Data> <Data>fa6f82b9-24cd-11e4-80a8-94de806ed9cb</Data> </EventData> And the general error details Faulting application name: Explorer.EXE, version: 6.1.7601.17567, time stamp: 0x4d672ee4 Faulting module name: vrfcore.dll, version: 6.3.9600.16384, time stamp: 0x5215f8f5 Exception code: 0x80000003 Fault offset: 0x0000000000003a00 Faulting process id: 0xc38 Faulting application start time: 0x01cfb84e5e852c5f Faulting application path: C:\Windows\Explorer.EXE Faulting module path: C:\Windows\SYSTEM32\vrfcore.dll Report Id: 9dc19e6d-2441-11e4-9f8a-94de806ed9cb Another probably unrelated error that I seem to be getting pretty often. Event filter with query "SELECT * FROM __InstanceModificationEvent WITHIN 60 WHERE TargetInstance ISA "Win32_Processor" AND TargetInstance.LoadPercentage > 99" could not be reactivated in namespace "//./root/CIMV2" because of error 0x80041003. Events cannot be delivered through this filter until the problem is corrected. My explorer tab in Autoruns seen below along with the error when I try to uncheck something. I should add that I seem to be able to disable shell extensions with ShellExView but I still can't get explorer to start correctly. EXPLORER SHELL UPDATE - See screenshot below I can access the explorer right click menu through a file manager I downloaded called NexusFile, but still no luck starting explorer. Another round of errors that I am getting regarding Windows Search Service The search service has detected corrupted data files in the index {id=4700}. The service will attempt to automatically correct this problem by rebuilding the index. Details: The content index catalog is corrupt. (HRESULT : 0xc0041801) (0xc0041801) followed by The Windows Search Service is being stopped because there is a problem with the indexer: The catalog is corrupt. Details: The content index catalog is corrupt. (HRESULT : 0xc0041801) (0xc0041801 and The plug-in in <Search.JetPropStore> cannot be initialized. Context: Windows Application, SystemIndex Catalog Details: The content index catalog is corrupt. (HRESULT : 0xc0041801) (0xc0041801) and The gatherer object cannot be initialized. Context: Windows Application, SystemIndex Catalog Details: The content index catalog is corrupt. (HRESULT : 0xc0041801) (0xc0041801) and The Windows Search Service cannot load the property store information. Context: Windows Application, SystemIndex Catalog Details: The content index database is corrupt. (HRESULT : 0xc0041800) (0xc0041800) WER Log http://pastebin.com/WXKGDT4Q I'll add information as I remember it or people request it.

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  • File Access problems with SLES 10 SP2 OES2 SP1

    - by Blackhawk131
    We have identified a couple of repeatable, demonstrable scenarios with unexplained rejected folder access on our servers for Mac users. Hopefully, this can be presented to Novell for a solution. What we did to demonstrate scenario 1; 1. setup a PC and Mac side-by-side 2. login to our server and open up to a central location on both Mac and PC 3. on the PC in that central location create a folder 4. on the Mac in that central location drag the created folder to the Mac desktop, this should work fine, no problem 5. on the PC rename that folder 6. on the Mac drag a file to that renamed folder, this should error with the following message; a. You cannot copy some of these items to the destination because their names are too long for the destination. Do you want to skip copying these items and continue copying the other items? b. Select skip, response is the filename is copied to the location with zero or small byte size. Try opening it and you get file is corrupted error message. What we did to demonstrate scenario 2; 1. setup a PC and Mac side-by-side 2. login to our server and open up to a central location on both Mac and PC 3. on the PC in that central location create a folder then create a subfolder 4. copy some content into the subfolder 5. on the Mac in that central location drag the created top level folder to the Mac desktop, this should work fine, no problem 6. on the PC rename that subfolder 7. on the Mac drag that top level folder to the Mac desktop, this should error on the Mac with the following; a. The operation cannot be completed because you do not have sufficient privileges for b. The operation cannot be completed because you do not have sufficient privileges for 8. on the Mac, if you open that subfolder you can see the file copied in step 4 above but, you can not open that file, you get the following message if you try; a. There was an error opening this document. You do not have permission to open this file. 9. on the PC drag some content into the top level folder 10. on the Mac you can open that file directly from the server or copy it locally, no problem, however-the subfolder is still corrupted or locked, whichever 11. on the PC rename the top level folder 12. on the Mac that same file just opened in step 10 above is now not accessible, get the following message; a. The document could not be opened. I have observed some variances in the above. For instance, a change on the PC side may take a moment before you can observer or act on the Mac side - kind of like the server is slow to respond. Also, the error message may vary. However, the key is once a folder, or subfolder, gets renamed by a PC, Mac problems commence. The solution is to create a new folder from a PC and copy the contents of the corrupted folder to the new folder and not rename the folder name. This has to be done on a PC because the corrupted folder is not accessible by a Mac user. Another problem that dovetails with the above is that we know certain characters are not allowed for PC folder or filenames. If a Mac user creates a folder with a slash in the file name, from the PC the user does not see that slash in the name. As soon as the PC user copies a file to that folder, the Mac user is locked from that folder. Will get the following error message; - Sorry, the operation could not be completed because an unexpected error occurred. - (Error code - 50) In addition to the above mentioned character issue with folders, the problem is more evil with filenames. If, for example, you create a file with a slash in the filename on a Mac and copy it to the server you will get the following error message; - You cannot copy some of these items to the destination because their names are too long for the destination. Do you want to skip copying these items and continue copying the other items? Select either Stop or Skip buttons. It does not matter which button is selected. The file name gets copied to the destination location at a reduced size. Depending on the file type, the icon associated with the file may or may not be present. Furthermore, if you open that file on the server you will get the following message; - Couldnt open the file. It may be corrupt or a file format that doesnt recognize. From the users perspective, if they are not observant of the icon or file size, they may disregard the error message and think their file has copied as intended. Only later do they discover the file is corrupt if they open that file. I want to make a note on this problem. It is the PC causing the issue. You can change folder and file names all day on a MAC and you don't have a problem as long as a character is not the issue. Once you change the file name or folder name from a PC the entire folder structure from that level down is corrupted. But it has to be resolved from a PC by creating a new folder and copying the contents to the new folder like stated above. Is something not configured correctly? SUSE Linux Enterprise Server 10 (x86_64) VERSION = 10 PATCHLEVEL = 2 LSB_VERSION="core-2.0-noarch:core-3.0-noarch:core-2.0-x86_64:core-3.0-x86_64" Novell Open Enterprise Server 2.0.1 (x86_64) VERSION = 2.0.1 PATCHLEVEL = 1 BUILD Note: We use Novell clients on all windows systems to connect to the servers for file access and network storage. We use AFP to allow OSx systems to connect to servers.

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  • Embedding mercurial revision information in Visual Studio c# projects automatically

    - by Mark Booth
    Original Problem In building our projects, I want the mercurial id of each repository to be embedded within the product(s) of that repository (the library, application or test application). I find it makes it so much easier to debug an application ebing run by custiomers 8 timezones away if you know precisely what went into building the particular version of the application they are using. As such, every project (application or library) in our systems implement a way of getting at the associated revision information. I also find it very useful to be able to see if an application has been compiled with clean (un-modified) changesets from the repository. 'Hg id' usefully appends a + to the changeset id when there are uncommitted changes in a repository, so this allows is to easily see if people are running a clean or a modified version of the code. My current solution is detailed below, and fulfills the basic requirements, but there are a number of problems with it. Current Solution At the moment, to each and every Visual Studio solution, I add the following "Pre-build event command line" commands: cd $(ProjectDir) HgID I also add an HgID.bat file to the Project directory: @echo off type HgId.pre > HgId.cs For /F "delims=" %%a in ('hg id') Do <nul >>HgID.cs set /p = @"%%a" echo ; >> HgId.cs echo } >> HgId.cs echo } >> HgId.cs along with an HgId.pre file, which is defined as: namespace My.Namespace { /// <summary> Auto generated Mercurial ID class. </summary> internal class HgID { /// <summary> Mercurial version ID [+ is modified] [Named branch]</summary> public const string Version = When I build my application, the pre-build event is triggered on all libraries, creating a new HgId.cs file (which is not kept under revision control) and causing the library to be re-compiled with with the new 'hg id' string in 'Version'. Problems with the current solution The main problem is that since the HgId.cs is re-created at each pre-build, every time we need to compile anything, all projects in the current solution are re-compiled. Since we want to be able to easily debug into our libraries, we usually keep many libraries referenced in our main application solution. This can result in build times which are significantly longer than I would like. Ideally I would like the libraries to compile only if the contents of the HgId.cs file has actually changed, as opposed to having been re-created with exactly the same contents. The second problem with this method is it's dependence on specific behaviour of the windows shell. I've already had to modify the batch file several times, since the original worked under XP but not Vista, the next version worked under Vista but not XP and finally I managed to make it work with both. Whether it will work with Windows 7 however is anyones guess and as time goes on, I see it more likely that contractors will expect to be able to build our apps on their Windows 7 boxen. Finally, I have an aesthetic problem with this solution, batch files and bodged together template files feel like the wrong way to do this. My actual questions How would you solve/how are you solving the problem I'm trying to solve? What better options are out there than what I'm currently doing? Rejected Solutions to these problems Before I implemented the current solution, I looked at Mercurials Keyword extension, since it seemed like the obvious solution. However the more I looked at it and read peoples opinions, the more that I came to the conclusion that it wasn't the right thing to do. I also remember the problems that keyword substitution has caused me in projects at previous companies (just the thought of ever having to use Source Safe again fills me with a feeling of dread *8'). Also, I don't particularly want to have to enable Mercurial extensions to get the build to complete. I want the solution to be self contained, so that it isn't easy for the application to be accidentally compiled without the embedded version information just because an extension isn't enabled or the right helper software hasn't been installed. I also thought of writing this in a better scripting language, one where I would only write HgId.cs file if the content had actually changed, but all of the options I could think of would require my co-workers, contractors and possibly customers to have to install software they might not otherwise want (for example cygwin). Any other options people can think of would be appreciated. Update Partial solution Having played around with it for a while, I've managed to get the HgId.bat file to only overwrite the HgId.cs file if it changes: @echo off type HgId.pre > HgId.cst For /F "delims=" %%a in ('hg id') Do <nul >>HgId.cst set /p = @"%%a" echo ; >> HgId.cst echo } >> HgId.cst echo } >> HgId.cst fc HgId.cs HgId.cst >NUL if %errorlevel%==0 goto :ok copy HgId.cst HgId.cs :ok del HgId.cst Problems with this solution Even though HgId.cs is no longer being re-created every time, Visual Studio still insists on compiling everything every time. I've tried looking for solutions and tried checking "Only build startup projects and dependencies on Run" in Tools|Options|Projects and Solutions|Build and Run but it makes no difference. The second problem also remains, and now I have no way to test if it will work with Vista, since that contractor is no longer with us. If anyone can test this batch file on a Windows 7 and/or Vista box, I would appreciate hearing how it went. Finally, my aesthetic problem with this solution, is even strnger than it was before, since the batch file is more complex and this there is now more to go wrong. If you can think of any better solution, I would love to hear about them.

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  • Yet another C# Deadlock Debugging Question

    - by Roo
    Hi All, I have a multi-threaded application build in C# using VS2010 Professional. It's quite a large application and we've experienced the classing GUI cross-threading and deadlock issues before, but in the past month we've noticed the appears to lock up when left idle for around 20-30 minutes. The application is irresponsive and although it will repaint itself when other windows are dragged in front of the application and over it, the GUI still appears to be locked... interstingly (unlike if the GUI thread is being used for a considerable amount of time) the Close, Maximise and minimise buttons are also irresponsive and when clicked the little (Not Responding...) text is not displayed in the title of the application i.e. Windows still seems to think it's running fine. If I break/pause the application using the debugger, and view the threads that are running. There are 3 threads of our managed code that are running, and a few other worker threads whom the source code cannot be displayed for. The 3 threads that run are: The main/GUI thread A thread that loops indefinitely A thread that loops indefinitely If I step into threads 2 and 3, they appear to be looping correctly. They do not share locks (even with the main GUI thread) and they are not using the GUI thread at all. When stepping into the main/GUI thread however, it's broken on Application.Run... This problem screams deadlock to me, but what I don't understand is if it's deadlock, why can't I see the line of code the main/GUI thread is hanging on? Any help will be greatly appreciated! Let me know if you need more information... Cheers, Roo -----------------------------------------------------SOLUTION-------------------------------------------------- Okay, so the problem is now solved. Thanks to everyone for their suggestions! Much appreciated! I've marked the answer that solved my initial problem of determining where on the main/UI thread the application hangs (I handn't turned off the "Enable Just My Code" option). The overall issue I was experiencing was indeed Deadlock, however. After obtaining the call-stack and popping the top half of it into Google I came across this which explains exactly what I was experiencing... http://timl.net/ This references a lovely guide to debugging the issue... http://www.aaronlerch.com/blog/2008/12/15/debugging-ui/ This identified a control I was constructing off the GUI thread. I did know this, however, and was marshalling calls correctly, but what I didn't realise was that behind the scenes this Control was subscribing to an event or set of events that are triggered when e.g. a Windows session is unlocked or the screensaver exits. These calls are always made on the main/UI thread and were blocking when it saw the call was made on the incorrect thread. Kim explains in more detail here... http://krgreenlee.blogspot.com/2007/09/onuserpreferencechanged-hang.html In the end I found an alternative solution which did not require this Control off the main/UI thread. That appears to have solved the problem and the application no longer hangs. I hope this helps anyone who's confronted by a similar problem. Thanks again to everyone on here who helped! (and indirectly, the delightful bloggers I've referenced above!) Roo -----------------------------------------------------SOLUTION II-------------------------------------------------- Aren't threading issues delightful...you think you've solved it, and a month down the line it pops back up again. I still believe the solution above resolved an issue that would cause simillar behaviour, but we encountered the problem again. As we spent a while debugging this, I thought I'd update this question with our (hopefully) final solution: The problem appears to have been a bug in the Infragistics components in the WinForms 2010.1 release (no hot fixes). We had been running from around the time the freeze issue appeared (but had also added a bunch of other stuff too). After upgrading to WinForms 2010.3, we've yet to reproduce the issue (deja vu). See my question here for a bit more information: 'http://stackoverflow.com/questions/4077822/net-4-0-and-the-dreaded-onuserpreferencechanged-hang'. Hans has given a nice summary of the general issue. I hope this adds a little to the suggestions/information surrounding the nutorious OnUserPreferenceChanged Hang (or whatever you'd like to call it). Cheers, Roo

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  • Replacing objects, handling clones, dealing with write logs

    - by Alix
    Hi everyone, I'm dealing with a problem I can't figure out how to solve, and I'd love to hear some suggestions. [NOTE: I realise I'm asking several questions; however, answers need to take into account all of the issues, so I cannot split this into several questions] Here's the deal: I'm implementing a system that underlies user applications and that protect shared objects from concurrent accesses. The application programmer (whose application will run on top of my system) defines such shared objects like this: public class MyAtomicObject { // These are just examples of fields you may want to have in your class. public virtual int x { get; set; } public virtual List<int> list { get; set; } public virtual MyClassA objA { get; set; } public virtual MyClassB objB { get; set; } } As you can see they declare the fields of their class as auto-generated properties (auto-generated means they don't need to implement get and set). This is so that I can go in and extend their class and implement each get and set myself in order to handle possible concurrent accesses, etc. This is all well and good, but now it starts to get ugly: the application threads run transactions, like this: The thread signals it's starting a transaction. This means we now need to monitor its accesses to the fields of the atomic objects. The thread runs its code, possibly accessing fields for reading or writing. If there are accesses for writing, we'll hide them from the other transactions (other threads), and only make them visible in step 3. This is because the transaction may fail and have to roll back (undo) its updates, and in that case we don't want other threads to see its "dirty" data. The thread signals it wants to commit the transaction. If the commit is successful, the updates it made will now become visible to everyone else. Otherwise, the transaction will abort, the updates will remain invisible, and no one will ever know the transaction was there. So basically the concept of transaction is a series of accesses that appear to have happened atomically, that is, all at the same time, in the same instant, which would be the moment of successful commit. (This is as opposed to its updates becoming visible as it makes them) In order to hide the write accesses in step 2, I clone the accessed field (let's say it's the field list) and put it in the transaction's write log. After that, any time the transaction accesses list, it will actually be accessing the clone in its write log, and not the global copy everyone else sees. Like this, any changes it makes will be done to the (invisible) clone, not to the global copy. If in step 3 the commit is successful, the transaction should replace the global copy with the updated list it has in its write log, and then the changes become visible for everyone else at once. It would be something like this: myAtomicObject.list = updatedCloneOfListInTheWriteLog; Problem #1: possible references to the list. Let's say someone puts a reference to the global list in a dictionary. When I do... myAtomicObject.list = updatedCloneOfListInTheWriteLog; ...I'm just replacing the reference in the field list, but not the real object (I'm not overwriting the data), so in the dictionary we'll still have a reference to the old version of the list. A possible solution would be to overwrite the data (in the case of a list, empty the global list and add all the elements of the clone). More generically, I would need to copy the fields of one list to the other. I can do this with reflection, but that's not very pretty. Is there any other way to do it? Problem #2: even if problem #1 is solved, I still have a similar problem with the clone: the application programmer doesn't know I'm giving him a clone and not the global copy. What if he puts the clone in a dictionary? Then at commit there will be some references to the global copy and some to the clone, when in truth they should all point to the same object. I thought about providing a wrapper object that contains both the cloned list and a pointer to the global copy, but the programmer doesn't know about this wrapper, so they're not going to use the pointer at all. The wrapper would be like this: public class Wrapper<T> : T { // This would be the pointer to the global copy. The local data is contained in whatever fields the wrapper inherits from T. private T thisPtr; } I do need this wrapper for comparisons: if I have a dictionary that has an entry with the global copy as key, if I look it up with the clone, like this: dictionary[updatedCloneOfListInTheWriteLog] I need it to return the entry, that is, to think that updatedCloneOfListInTheWriteLog and the global copy are the same thing. For this, I can just override Equals, GetHashCode, operator== and operator!=, no problem. However I still don't know how to solve the case in which the programmer unknowingly inserts a reference to the clone in a dictionary. Problem #3: the wrapper must extend the class of the object it wraps (if it's wrapping MyClassA, it must extend MyClassA) so that it's accepted wherever an object of that class (MyClass) would be accepted. However, that class (MyClassA) may be final. This is pretty horrible :$. Any suggestions? I don't need to use a wrapper, anything you can think of is fine. What I cannot change is the write log (I need to have a write log) and the fact that the programmer doesn't know about the clone. I hope I've made some sense. Feel free to ask for more info if something needs some clearing up. Thanks so much!

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  • Inconsistent results in R with RNetCDF - why?

    - by sarcozona
    I am having trouble extracting data from NetCDF data files using RNetCDF. The data files each have 3 dimensions (longitude, latitude, and a date) and 3 variables (latitude, longitude, and a climate variable). There are four datasets, each with a different climate variable. Here is some of the output from print.nc(p8m.tmax) for clarity. The other datasets are identical except for the specific climate variable. dimensions: month = UNLIMITED ; // (1368 currently) lat = 3105 ; lon = 7025 ; variables: float lat(lat) ; lat:long_name = "latitude" ; lat:standard_name = "latitude" ; lat:units = "degrees_north" ; float lon(lon) ; lon:long_name = "longitude" ; lon:standard_name = "longitude" ; lon:units = "degrees_east" ; short tmax(lon, lat, month) ; tmax:missing_value = -9999 ; tmax:_FillValue = -9999 ; tmax:units = "degree_celsius" ; tmax:scale_factor = 0.01 ; tmax:valid_min = -5000 ; tmax:valid_max = 6000 ; I am getting behavior I don't understand when I use the var.get.nc function from the RNetCDF package. For example, when I attempt to extract 82 values beginning at stval from the maximum temperature data (p8m.tmax <- open.nc(tmaxdataset.nc)) with > var.get.nc(p8m.tmax,'tmax', start=c(lon_val, lat_val, stval),count=c(1,1,82)) (where lon_val and lat_val specify the location in the dataset of the coordinates I'm interested in and stval is stval is set to which(time_vec==200201), which in this case equaled 1285.) I get Error: Invalid argument But after successfully extracting 80 and 81 values > var.get.nc(p8m.tmax,'tmax', start=c(lon_val, lat_val, stval),count=c(1,1,80)) > var.get.nc(p8m.tmax,'tmax', start=c(lon_val, lat_val, stval),count=c(1,1,81)) the command with 82 works: > var.get.nc(p8m.tmax,'tmax', start=c(lon_val, lat_val, stval),count=c(1,1,82)) [1] 444 866 1063 ... [output snipped] The same problem occurs in the identically structured tmin file, but at 36 instead of 82: > var.get.nc(p8m.tmin,'tmin', start=c(lon_val, lat_val, stval),count=c(1,1,36)) produces Error: Invalid argument But after repeating with counts of 30, 31, etc > var.get.nc(p8m.tmin,'tmin', start=c(lon_val, lat_val, stval), count=c(1,1,36)) works. These examples make it seem like the function is failing at the last count, but that actually isn't the case. In the first example, var.get.nc gave Error: Invalid argument after I asked for 84 values. I then narrowed the failure down to the 82nd count by varying the starting point in the dataset and asking for only 1 value at a time. The particular number the problem occurs at also varies. I can close and reopen the dataset and have the problem occur at a different location. In the particular examples above, lon_val and lat_val are 1595 and 1751, respectively, identifying the location in the dataset along the lat and lon dimensions for the latitude and longitude I'm interested in. The 1595th latitude and 1751th longitude are not the problem, however. The problem occurs with all other latitude and longitudes I've tried. Varying the starting location in the dataset along the climate variable dimension (stval) and/or specifying it different (as a number in the command instead of the object stval) also does not fix the problem. This problem doesn't always occur. I can run identical code three times in a row (clearing all objects in between runs) and get a different outcome each time. The first run may choke on the 7th entry I'm trying to get, the second might work fine, and the third run might choke on the 83rd entry. I'm absolutely baffled by such inconsistent behavior. The open.nc function has also started to fail with the same Error: Invalid argument. Like the var.get.nc problems, it also occurs inconsistently. Does anyone know what causes the initial failure to extract the variable? And how I might prevent it? Could have to do with the size of the data files (~60GB each) and/or the fact that I'm accessing them through networked drives? This was also asked here: https://stat.ethz.ch/pipermail/r-help/2011-June/281233.html > sessionInfo() R version 2.13.0 (2011-04-13) Platform: i386-pc-mingw32/i386 (32-bit) locale: [1] LC_COLLATE=English_United States.1252 LC_CTYPE=English_United States.1252 [3] LC_MONETARY=English_United States.1252 LC_NUMERIC=C [5] LC_TIME=English_United States.1252 attached base packages: [1] stats graphics grDevices utils datasets methods base other attached packages: [1] reshape_0.8.4 plyr_1.5.2 RNetCDF_1.5.2-2 loaded via a namespace (and not attached): [1] tools_2.13.0

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  • Do unit tests sometimes break encapsulation?

    - by user1288851
    I very often hear the following: "If you want to test private methods, you'd better put that in another class and expose it." While sometimes that's the case and we have a hiding concept inside our class, other times you end up with classes that have the same attributes (or, worst, every attribute of one class become a argument on a method in the other class) and exposes functionality that is, in fact, implementation detail. Specially on TDD, when you refactor a class with public methods out of a previous tested class, that class is now part of your interface, but has no tests to it (since you refactored it, and is a implementation detail). Now, I may be not finding an obvious better answer, but if my answer is the "correct", that means that sometimes writting unit tests can break encapsulation, and divide the same responsibility into different classes. A simple example would be testing a setter method when a getter is not actually needed for anything in the real code. Please when aswering don't provide simple answers to specific cases I may have written. Rather, try to explain more of the generic case and theoretical approach. And this is neither language specific. Thanks in advance. EDIT: The answer given by Matthew Flynn was really insightful, but didn't quite answer the question. Altough he made the fair point that you either don't test private methods or extract them because they really are other concern and responsibility (or at least that was what I could understand from his answer), I think there are situations where unit testing private methods is useful. My primary example is when you have a class that has one responsibility but the output (or input) that it gives (takes) is just to complex. For example, a hashing function. There's no good way to break a hashing function apart and mantain cohesion and encapsulation. However, testing a hashing function can be really tough, since you would need to calculate by hand (you can't use code calculation to test code calculation!) the hashing, and test multiple cases where the hash changes. In that way (and this may be a question worth of its own topic) I think private method testing is the best way to handle it. Now, I'm not sure if I should ask another question, or ask it here, but are there any better way to test such complex output (input)? OBS: Please, if you think I should ask another question on that topic, leave a comment. :)

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  • Type Casting variables in PHP: Is there a practical example?

    - by Stephen
    PHP, as most of us know, has weak typing. For those who don't, PHP.net says: PHP does not require (or support) explicit type definition in variable declaration; a variable's type is determined by the context in which the variable is used. Love it or hate it, PHP re-casts variables on-the-fly. So, the following code is valid: $var = "10"; $value = 10 + $var; var_dump($value); // int(20) PHP also alows you to explicitly cast a variable, like so: $var = "10"; $value = 10 + $var; $value = (string)$value; var_dump($value); // string(2) "20" That's all cool... but, for the life of me, I cannot conceive of a practical reason for doing this. I don't have a problem with strong typing in languages that support it, like Java. That's fine, and I completely understand it. Also, I'm aware of—and fully understand the usefulness of—type hinting in function parameters. The problem I have with type casting is explained by the above quote. If PHP can swap types at-will, it can do so even after you force cast a type; and it can do so on-the-fly when you need a certain type in an operation. That makes the following valid: $var = "10"; $value = (int)$var; $value = $value . ' TaDa!'; var_dump($value); // string(8) "10 TaDa!" So what's the point? Can anyone show me a practical application or example of type casting—one that would fail if type casting were not involved? I ask this here instead of SO because I figure practicality is too subjective. Edit in response to Chris' comment Take this theoretical example of a world where user-defined type casting makes sense in PHP: You force cast variable $foo as int -- (int)$foo. You attempt to store a string value in the variable $foo. PHP throws an exception!! <--- That would make sense. Suddenly the reason for user defined type casting exists! The fact that PHP will switch things around as needed makes the point of user defined type casting vague. For example, the following two code samples are equivalent: // example 1 $foo = 0; $foo = (string)$foo; $foo = '# of Reasons for the programmer to type cast $foo as a string: ' . $foo; // example 2 $foo = 0; $foo = (int)$foo; $foo = '# of Reasons for the programmer to type cast $foo as a string: ' . $foo;

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  • Data validation best practices: how can I better construct user feedback?

    - by Cory Larson
    Data validation, whether it be domain object, form, or any other type of input validation, could theoretically be part of any development effort, no matter its size or complexity. I sometimes find myself writing informational or error messages that might seem harsh or demanding to unsuspecting users, and frankly I feel like there must be a better way to describe the validation problem to the user. I know that this topic is subjective and argumentative. I've migrated this question from StackOverflow where I originally asked it with little response. Basically, I'm looking for good resources on data validation and user feedback that results from it at a theoretical level. Topics and questions I'm interested in are: Content Should I be describing what the user did correctly or incorrectly, or simply what was expected? How much detail can the user read before they get annoyed? (e.g. Is "Username cannot exceed 20 characters." enough, or should it be described more fully, such as "The username cannot be empty, and must be at least 6 characters but cannot exceed 30 characters."?) Grammar How do I decide between phrases like "must not," "may not," or "cannot"? Delivery This can depend on the project, but how should the information be delivered to the user? Should it be obtrusive (e.g. JavaScript alerts) or friendly? Should they be displayed prominently? Immediately (i.e. without confirmation steps, etc.)? Logging Do you bother logging validation errors? Internationalization Some cultures prefer or better understand directness over subtlety and vice-versa (e.g. "Don't do that!" vs. "Please check what you've done."). How do I cater to the majority of users? I may edit this list as I think more about the topic, but I'm genuinely interested in proper user feedback techniques. I'm looking for things like research results, poll results, etc. I've developed and refined my own techniques over the years that users seem to be okay with, but I work in an environment where the users prefer to adapt to what you give them over speaking up about things they don't like. I'm interested in hearing your experiences in addition to any resources to which you may be able to point me.

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  • &ldquo;Our Users are Doing Something Surprising&rdquo;&hellip; but what?

    - by antonio romero
    I’ve just started a discussion on the OWB Linkedin Group based on a blog post from Laura Klein’s “Users Know” blog, entitled “Your Users are Doing Something Surprising”… As a PM I found the post thought-provoking and a good reminder to learn from our customers: ...You may have written user stories and work flows... But you know who didn’t read your user stories? That’s right: your users. The result? Somewhere out there, a whole lot of your users are doing something totally unexpected with your product.... Your customers want to do something with your product so badly that they’re going out of their way to come up with clever ways to do it on their own. There are three excellent reasons for you to know what your customers are actually doing with your product: So you know if you are missing an opportunity to pivot your product or marketing So you know if you are missing an important feature So you don’t accidentally destroy a commonly used workaround or "unplanned feature" Truer words were rarely blogged. In fact just in the last few weeks I have had several "users" (some customers, and some internal to Oracle, in fact) turn up having built unexpected but powerful things around OWB, because it has such extensibility mechanisms built into it: OMB*Plus, the old Java APIs back before 10.2, and now the code template/knowledge module framework OWB shares with ODI. Some of our external users show astounding knowledge of how to make OWB really sing. (We hope to feature case studies from several of them over the course of the year on the OWB blog.) My question to all of you: can you identify things you have done or are doing with OWB or that you depend on in it that you think would come as a surprise to us? This could be either some development so advanced as to leave us all gob-smacked, or just some common (to you) thing that you use it for that you find enormously valuable but that you think is a bit off the theoretical "main line" use case of loading data warehouses. I invite the readers of this blog to come visit the OWB and ODI LinkedIn group and share their unusual applications of OWB or the very ordinary-looking features that you don’t want us to forget or would like us to extend. Your anecdotes will impress the crowd and will also help shape future data integration products from Oracle... Come on, surprise us. :)

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  • Data validation best practices: how can I better construct user feedback?

    - by Cory Larson
    Data validation, whether it be domain object, form, or any other type of input validation, could theoretically be part of any development effort, no matter its size or complexity. I sometimes find myself writing informational or error messages that might seem harsh or demanding to unsuspecting users, and frankly I feel like there must be a better way to describe the validation problem to the user. I know that this topic is subjective and argumentative. StackOverflow might not be the proper channel for diving into this subject, but like I've mentioned, we all run into this at some point or another. There are so many StackExchange sites now; if there is a better one, feel free to share! Basically, I'm looking for good resources on data validation and user feedback that results from it at a theoretical level. Topics and questions I'm interested in are: Content Should I be describing what the user did correctly or incorrectly, or simply what was expected? How much detail can the user read before they get annoyed? (e.g. Is "Username cannot exceed 20 characters." enough, or should it be described more fully, such as "The username cannot be empty, and must be at least 6 characters but cannot exceed 30 characters."?) Grammar How do I decide between phrases like "must not," "may not," or "cannot"? Delivery This can depend on the project, but how should the information be delivered to the user? Should it be obtrusive (e.g. JavaScript alerts) or friendly? Should they be displayed prominently? Immediately (i.e. without confirmation steps, etc.)? Logging Do you bother logging validation errors? Internationalization Some cultures prefer or better understand directness over subtlety and vice-versa (e.g. "Don't do that!" vs. "Please check what you've done."). How do I cater to the majority of users? I may edit this list as I think more about the topic, but I'm genuinely interest in proper user feedback techniques. I'm looking for things like research results, poll results, etc. I've developed and refined my own techniques over the years that users seem to be okay with, but I work in an environment where the users prefer to adapt to what you give them over speaking up about things they don't like. I'm interested in hearing your experiences in addition to any resources to which you may be able to point me.

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  • SQL Contests – Solution – Identify the Database Celebrity

    - by Pinal Dave
    Last week we were running contest Identify the Database Celebrity and we had received a fantastic response to the contest. Thank you to the kind folks at NuoDB as they had offered two USD 100 Amazon Gift Cards to the winners of the contest. We had also additional contest that users have to download and install NuoDB and identified the sample database. You can read about the contest over here. Here is the answer to the questions which we had asked earlier in the contest. Part 1: Identify Database Celebrity Personality 1 – Edgar Frank “Ted” Codd (August 19, 1923 – April 18, 2003) was an English computer scientist who, while working for IBM, invented the relational model for database management, the theoretical basis for relational databases. He made other valuable contributions to computer science, but the relational model, a very influential general theory of data management, remains his most mentioned achievement. (Wki) Personality 2 – James Nicholas “Jim” Gray (born January 12, 1944; lost at sea January 28, 2007; declared deceased May 16, 2012) was an American computer scientist who received the Turing Award in 1998 “for seminal contributions to database and transaction processing research and technical leadership in system implementation.” (Wiki) Personality 3 – Jim Starkey (born January 6, 1949 in Illinois) is a database architect responsible for developing InterBase, the first relational database to support multi-versioning, the blob column type, type event alerts, arrays and triggers. Starkey is the founder of several companies, including the web application development and database tool company Netfrastructure and NuoDB. (Wiki) Part 2: Identify NuoDB Samples Database Names In this part of the contest one has to Download NuoDB and install the sample database Hockey. Hockey is sample database and contains few tables. Users have to install sample database and inform the name of the sample databases. Here is the valid answer. HOCKEY PLAYERS SCORING TEAM Once again, it was indeed fun to run this contest. I have received great feedback about it and lots of people wants me to run similar contest in future. I promise to run similar interesting contests in the near future. Winners Within next two days, we will let winners send emails. Winners will have to confirm their email address and NuoDB team will send them directly Amazon Cards. Once again it was indeed fun to run this contest. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL

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  • How does rc job work / order of (contradicting) "start on ..." and "stop on ..." stanzas

    - by Binarus
    Hi, I just can't understand how Upstart's rc job definition in Natty 11.04 works. To illustrate the problem, here is the definition (empty lines and comments are left out): start on runlevel [0123456] stop on runlevel [!$RUNLEVEL] export RUNLEVEL export PREVLEVEL console output env INIT_VERBOSE task exec /etc/init.d/rc $RUNLEVEL Let's suppose we currently are in runlevel 2 and the rc job is stopped (that is exactly the situation after booting my box and logging in via SSH). Now, let's assume that the system switches to runlevel 3, for example due to a command like "telinit 3" given by root. What will happen to the rc job? Obviously, the rc job will be started since it is currently stopped and the event runlevel 3 is matching the start events. But from now on, things are unclear to me: According to the manual $RUNLEVEL evaluates to the new runlevel when the job is started (that means 3 in our example). Therefore, the next stanza "stop on runlevel [!$RUNLEVEL]" translates to "stop on runlevel [!3]"; that means we have a first stanza which will trigger the job, but the second stanza will never stop the job and seems to be useless. Since I know that the Ubuntu / Upstart people won't do useless things, I must be heavily misunderstanding something. I would be grateful for any explanation. While trying to understand this, an additional question came to my mind. If I had contradicting start and stop triggers, for example start on foo stop on foo what would happen? I swear I never will do that, but I am nevertheless very interested in how Upstart handles that on the theoretical level. Thank you very much! Editing the question as a reaction on geekosaur's first answer: I can see the parallelism, but it is not that easy (at least, not to me). Let's assume the job aurrently is still running, and a new runlevel event comes in (of course, the new runlevel is different from the current one). Then, the following should happen: 1) The job is single instance. That means that "start on ..." won't be triggered since the job is currently running; $RUNLEVEL is not touched. 2) "stop on ..." will be triggered since the new runlevel is different from $RUNLEVEL, so the job will be aborted. 3) Now, the job is stopped and waiting. I can't see how it is restarted with the new runlevel. AFAIK, initctl emits events only once, so "start on ..." won't be triggered and the new runlevel won't be entered. I know that I still misunderstanding something, and I am grateful for explanations. Thank you very much!

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  • Upstart: How does rc job work / order of (contradicting) "start on ..." and "stop on ..." stanzas

    - by Binarus
    Hi, I just can't understand how Upstart's rc job definition in Natty 11.04 works. To illustrate the problem, here is the definition (empty lines and comments are left out): start on runlevel [0123456] stop on runlevel [!$RUNLEVEL] export RUNLEVEL export PREVLEVEL console output env INIT_VERBOSE task exec /etc/init.d/rc $RUNLEVEL Let's suppose we currently are in runlevel 2 and the rc job is stopped (that is exactly the situation after booting my box and logging in via SSH). Now, let's assume that the system switches to runlevel 3, for example due to a command like "telinit 3" given by root. What will happen to the rc job? Obviously, the rc job will be started since it is currently stopped and the event runlevel 3 is matching the start events. But from now on, things are unclear to me: According to the manual $RUNLEVEL evaluates to the new runlevel when the job is started (that means 3 in our example). Therefore, the next stanza "stop on runlevel [!$RUNLEVEL]" translates to "stop on runlevel [!3]"; that means we have a first stanza which will trigger the job, but the second stanza will never stop the job and seems to be useless. Since I know that the Ubuntu / Upstart people won't do useless things, I must be heavily misunderstanding something. I would be grateful for any explanation. While trying to understand this, an additional question came to my mind. If I had contradicting start and stop triggers, for example start on foo stop on foo what would happen? I swear I never will do that, but I am nevertheless very interested in how Upstart handles that on the theoretical level. Thank you very much! Editing the question as a reaction on geekosaur's first answer: I can see the parallelism, but it is not that easy (at least, not to me). Let's assume the job aurrently is still running, and a new runlevel event comes in (of course, the new runlevel is different from the current one). Then, the following should happen: 1) The job is single instance. That means that "start on ..." won't be triggered since the job is currently running; $RUNLEVEL is not touched. 2) "stop on ..." will be triggered since the new runlevel is different from $RUNLEVEL, so the job will be aborted. 3) Now, the job is stopped and waiting. I can't see how it is restarted with the new runlevel. AFAIK, initctl emits events only once, so "start on ..." won't be triggered and the new runlevel won't be entered. I know that I still misunderstanding something, and I am grateful for explanations. Thank you very much!

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  • Class instance clustering in object reference graph for multi-entries serialization

    - by Juh_
    My question is on the best way to cluster a graph of class instances (i.e. objects, the graph nodes) linked by object references (the -directed- edges of the graph) around specifically marked objects. To explain better my question, let me explain my motivation: I currently use a moderately complex system to serialize the data used in my projects: "marked" objects have a specific attributes which stores a "saving entry": the path to an associated file on disc (but it could be done for any storage type providing the suitable interface) Those object can then be serialized automatically (eg: obj.save()) The serialization of a marked object 'a' contains implicitly all objects 'b' for which 'a' has a reference to, directly s.t: a.b = b, or indirectly s.t.: a.c.b = b for some object 'c' This is very simple and basically define specific storage entries to specific objects. I have then "container" type objects that: can be serialized similarly (in fact their are or can-be "marked") they don't serialize in their storage entries the "marked" objects (with direct reference): if a and a.b are both marked, a.save() calls b.save() and stores a.b = storage_entry(b) So, if I serialize 'a', it will serialize automatically all objects that can be reached from 'a' through the object reference graph, possibly in multiples entries. That is what I want, and is usually provides the functionalities I need. However, it is very ad-hoc and there are some structural limitations to this approach: the multi-entry saving can only works through direct connections in "container" objects, and there are situations with undefined behavior such as if two "marked" objects 'a'and 'b' both have a reference to an unmarked object 'c'. In this case my system will stores 'c' in both 'a' and 'b' making an implicit copy which not only double the storage size, but also change the object reference graph after re-loading. I am thinking of generalizing the process. Apart for the practical questions on implementation (I am coding in python, and use Pickle to serialize my objects), there is a general question on the way to attach (cluster) unmarked objects to marked ones. So, my questions are: What are the important issues that should be considered? Basically why not just use any graph parsing algorithm with the "attach to last marked node" behavior. Is there any work done on this problem, practical or theoretical, that I should be aware of? Note: I added the tag graph-database because I think the answer might come from that fields, even if the question is not.

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  • Behaviour Trees with irregular updates

    - by Robominister
    I'm interested in behaviour trees that aren't iterated every game tick, but every so often. (Edit: the tree could specify how many frames within the main game loop to wait before running its tick function again). Every theoretical implementation I have seen of behaviour trees talks of the tree search being carried out every game update - which seems necessary, because a leaf node (eg a behaviour, like 'return to base') needs to be constantly checked to see if is still running, failed or completed. Can anyone suggest how I might start implementing a tree that isnt run every tick, or point me in the direction of good material specific to this case (I am struggling to find anything)? My thoughts so far: action leaf nodes (when they start) must only push some kind of action object onto a list for an entity, rather than directly calling any code that makes the entity do something. The list of actions for the entity would be run every frame (update any that need to run, pop any that have completed from the list). the return state from a given action must be fed back into the tree, so that when we run the tree iteration again (and reach the same action leaf node - so the tree has so far determined that we ought to still be trying this action) - that the action has completed, or is still running etc. If my actual action code is running from an action list on an entity, then I possibly need to cancel previously running actions in the list - i am thinking that I can just delete the entire stack of queued up actions. I've seen the idea of ActionLists which block lower priority actions when a higher priority one is added, but this seems like very close logic to behaviour trees, and I dont want to be duplicating behaviour. This leaves me with some questions 1) How would I feed the action return state back into the tree? Its obvious I need to store some information relating to 'currently executing actions' on the entity, and check that in the tree tick, but I can't imagine how. 2) Does having a seperate behaviour tree (for deciding behaviour) and action list (for carrying out actual queued up actions) sound like a reasonable approach? 3) Is the approach of updating a behaviour tree irregularly actually used by anyone? It seems like a nice idea for budgeting ai search time when you have a lot of ai entities to process. (Edit) - I am also thinking about storing a single instance of a given behaviour tree in memory, and providing it by reference to any entity that uses it. So any information about what action was last selected for execution on an entity must be stored in a data context relative to the entity (which the tree can check). (I am probably answering my own questions as i go!) I hope I have expressed my questions adequately! Thanks in advance for any help :)

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  • Understanding the levels of computing

    - by RParadox
    Sorry, for my confused question. I'm looking for some pointers. Up to now I have been working mostly with Java and Python on the application layer and I have only a vague understanding of operating systems and hardware. I want to understand much more about the lower levels of computing, but it gets really overwhelming somehow. At university I took a class about microprogramming, i.e. how processors get hard-wired to implement the ASM codes. Up to now I always thought I wouldn't get more done if learned more about the "low level". One question I have is: how is it even possible that hardware gets hidden almost completely from the developer? Is it accurate to say that the operating system is a software layer for the hardware? One small example: in programming I have never come across the need to understand what L2 or L3 Cache is. For the typical business application environment one almost never needs to understand assembler and the lower levels of computing, because nowadays there is a technology stack for almost anything. I guess the whole point of these lower levels is to provide an interface to higher levels. On the other hand I wonder how much influence the lower levels can have, for example this whole graphics computing thing. So, on the other hand, there is this theoretical computer science branch, which works on abstract computing models. However, I also rarely encountered situations, where I found it helpful thinking in the categories of complexity models, proof verification, etc. I sort of know, that there is a complexity class called NP, and that they are kind of impossible to solve for a big number of N. What I'm missing is a reference for a framework to think about these things. It seems to me, that there all kinds of different camps, who rarely interact. The last few weeks I have been reading about security issues. Here somehow, much of the different layers come together. Attacks and exploits almost always occur on the lower level, so in this case it is necessary to learn about the details of the OSI layers, the inner workings of an OS, etc.

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  • Frame rate on one of two machines running same code seems to be capped at 60 for no reason

    - by dennmat
    ISSUE I recently moved a project from my laptop to my desktop(machine info below). On my laptop the exact same code displays the fps(and ms/f) correctly. On my desktop it does not. What I mean by this is on the laptop it will display 300 fps(for example) where on my desktop it will show only up to 60. If I add 100 objects to the game on the laptop I'll see my frame rate drop accordingly; the same test on the desktop results in no change and the frames stay at 60. It takes a lot(~300) entities before I'll see a frame drop on the desktop, then it will descend. It seems as though its "theoretical" frames would be 400 or 500 but will never actually get to that and only do 60 until there's too much to handle at 60. This 60 frame cap is coming from no where. I'm not doing any frame limiting myself. It seems like something external is limiting my loop iterations on the desktop, but for the last couple days I've been scratching my head trying to figure out how to debug this. SETUPS Desktop: Visual Studio Express 2012 Windows 7 Ultimate 64-bit Laptop: Visual Studio Express 2010 Windows 7 Ultimate 64-bit The libraries(allegro, box2d) are the same versions on both setups. CODE Main Loop: while(!abort) { frameTime = al_get_time(); if (frameTime - lastTime >= 1.0) { lastFps = fps/(frameTime - lastTime); lastTime = frameTime; avgMspf = cumMspf/fps; cumMspf = 0.0; fps = 0; } /** DRAWING/UPDATE CODE **/ fps++; cumMspf += al_get_time() - frameTime; } Note: There is no blocking code in the loop at any point. Where I'm at My understanding of al_get_time() is that it can return different resolutions depending on the system. However the resolution is never worse than seconds, and the double is represented as [seconds].[finer-resolution] and seeing as I'm only checking for a whole second al_get_time() shouldn't be responsible. My project settings and compiler options are the same. And I promise its the same code on both machines. My googling really didn't help me much, and although technically it's not that big of a deal. I'd really like to figure this out or perhaps have it explained, whichever comes first. Even just an idea of how to go about figuring out possible causes, because I'm out of ideas. Any help at all is greatly appreciated.

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  • Dell PowerEdge R720xd stuck in BIOS

    - by G_P
    I have a Dell PowerEdge R720xd that gets stuck in the BIOS when booting. It successfully gets past the "configuring memory" and "configuring iDRAC" screens, but once it shows the "CPLD version : 103" with the various management engine versions/patches, it just hangs. No errors messages are displayed. This started happening when we tried adding additional RAM to the machine. Since then, we tried re-seating the new memory which resulted in the same issue. Then, we took out all the new memory, and the problem persists. We have also tried pressing F2 to get into System Setup, but it just indicates "Entering System Setup" and hangs at the same point. Has anybody seen this issue before or have any ideas on what to try next? UPDATE After troubleshooting and trying to isolate the issue (stripping things down to a single CPU and single DIMM, same problem, swapping to the other CPU and a different DIMM, same problem), Dell support will be coming out to swap the system board.

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  • Intel Network Connection: This device cannot start. (Code 10)

    - by harryuser
    Hi, I have a Intel® Desktop Board DP55KG (see http://www.intel.com/products/desktop/motherboards/DP55KG/DP55KG-overview.htm), which has a Intel 82578DC Gigabit Network Connection on board. Additionally, I have a Intel PRO/1000 PT Dual Port Server Adapter in a PCI express slot and I am running Windows 7 Professional 32-bit. The problem I am having is that the Intel 82578DC Gigabit Network Connection will not start on boot with the following message: "This device cannot start. (Code 10)". Disabling and then enabling the device after boot makes the network connection work again without any problems, but as soon as I reboot the problem occurs again. Any suggestion how to fix this? I have seen this problem on another Intel S3420GP board as well in Windows 7 that is.

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  • Windows Server 2003 can't see Vista machine

    - by Django Reinhardt
    Hi there, I've got a real PITA problem that I'm sure has a really simple solution. I have a Windows Server 2003 machine that needs to be able to see the network name of a Vista box - but refuses to. It can see the Vista box (and even access its shared folder) if I enter the Vista box's IP address. Problem is: SQL Server refuses to do Replication with anything other than the "actual server name". That means that the 2003 machine needs to be able to connect through the Vista machines network name... not just its IP address. I'm guessing it's a simple incompatibility between OS's, but I'm sure there's got to be a simple way of fixing it. Note: Yes, the Vista machine can connect to 2003 machine, no problem. And other machines in the office can connect to both the Vista machine and 2003 (they have more recent OS's). Thanks for any help!

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  • Nginx + PHP-FPM on Ubuntu giving "upstream sent invalid status" on uploading Joomla extension zip file

    - by faridv
    I have a Ubuntu server running in an ESV VM emvironment and I've installed a webserver with this configuration: Nginx 1.0.5 PHP 5.3.6 with PHP-FMP Mysql 5.1.62 I have an installation of latest version of joomla on this server and when I try to upload an install package (zip file containing joomla's extension files) I get "502 Bad Gateway" with the following error in nginx log file: 2012/05/13 11:22:21 [error] 19911#0: *20 upstream sent invalid status "-1 Copy failed" while reading response header from upstream, client: 10.10.56.70, server: localhost, request: "POST /administrator/index.php?option=com_installer&view=install HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "radio.xx.xx", referrer: "http://radio.xx.xx/administrator/index.php?option=com_installer" I've searched all over the internet and I've changed too many parameters of php configuration, fpm config and nginx config including increasing execution times and etc but my problem still remains. I'm pretty sure it has nothing to do with my Joomla and problem is in webserver but there's no usable log messages, except above message. Can anyone help me with this problem?

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  • Unable to execute file in the temporary directory

    - by Bixal
    I am using Windows 8.1 Pro 64-bit. I see this error, almost everytime I launch an executable file (to install it) but not for all of them. I don't see the error when I use Run as Administrator. I looked around, and found a solution: I needed to give permissions to the current user for the temp file as shown in the picture below: The problem here is solved temporarily, but it goes back to give me the same problem after restarting the PC. What can I do to prevent such a thing? I don't really want to use the built in Administrator account all the time. Update: The problem is caused by the cracked version of Adobe Acrobat. And the root cause is the cracked amtlib.dll Read more here: http://www.sabernova.com/2013/12/cracked-adobe-acrobat-xi-will-revert.html#axzz2r8VSzZi9

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  • IIS mystery: "Deadlock detected" periodically makes site unavailable

    - by jskunkle
    A few times a day, our vb.net (IIS 6.0) website is randomly throwing the following error and becomes completely unavailable for 5-15 minutes at a time while the application is recycled: ISAPI 'c:\windows\microsoft.net\framework\v2.0.50727\aspnet_isapi.dll' reported itself as unhealthy for the following reason: 'Deadlock detected'. The website ran for months on the exact same server in beta without problem - but the problem started over the weekend when we made the site live. The live site is under some load but less than many of our other production websites. How should I attack this problem? I've looked into orphaning the worker process and creating a dump file - but I'm not sure how to analyze that. Any advice or information is appreciated. Thanks, Shane

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