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  • Re-Initialize RAID-0 in software after card failure

    - by Ben
    I'm working on a Friend's WD MyBook "1TB" HDD that is not mounting. When I got in to it, I discovered that it is really 2 500GB HDD's set up as RAID-0. It appears that the drives themselves are fine, but that the logic board has failed. My questions is this: can I re-initialize the RAID-0 using software RAID so that I can recover the data to another drive? If so, how and which software RAID would be best (Preferably open source. any platform OK).

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  • Domain Validation in a CQRS architecture

    - by Jupaol
    Basically I want to know if there is a better way to validate my domain entities. This is how I am planning to do it but I would like your opinion The first approach I considered was: class Customer : EntityBase<Customer> { public void ChangeEmail(string email) { if(string.IsNullOrWhitespace(email)) throw new DomainException(“...”); if(!email.IsEmail()) throw new DomainException(); if(email.Contains(“@mailinator.com”)) throw new DomainException(); } } I actually do not like this validation because even when I am encapsulating the validation logic in the correct entity, this is violating the Open/Close principle (Open for extension but Close for modification) and I have found that violating this principle, code maintenance becomes a real pain when the application grows up in complexity. Why? Because domain rules change more often than we would like to admit, and if the rules are hidden and embedded in an entity like this, they are hard to test, hard to read, hard to maintain but the real reason why I do not like this approach is: if the validation rules change, I have to come and edit my domain entity. This has been a really simple example but in RL the validation could be more complex So following the philosophy of Udi Dahan, making roles explicit, and the recommendation from Eric Evans in the blue book, the next try was to implement the specification pattern, something like this class EmailDomainIsAllowedSpecification : IDomainSpecification<Customer> { private INotAllowedEmailDomainsResolver invalidEmailDomainsResolver; public bool IsSatisfiedBy(Customer customer) { return !this.invalidEmailDomainsResolver.GetInvalidEmailDomains().Contains(customer.Email); } } But then I realize that in order to follow this approach I had to mutate my entities first in order to pass the value being valdiated, in this case the email, but mutating them would cause my domain events being fired which I wouldn’t like to happen until the new email is valid So after considering these approaches, I came out with this one, since I am going to implement a CQRS architecture: class EmailDomainIsAllowedValidator : IDomainInvariantValidator<Customer, ChangeEmailCommand> { public void IsValid(Customer entity, ChangeEmailCommand command) { if(!command.Email.HasValidDomain()) throw new DomainException(“...”); } } Well that’s the main idea, the entity is passed to the validator in case we need some value from the entity to perform the validation, the command contains the data coming from the user and since the validators are considered injectable objects they could have external dependencies injected if the validation requires it. Now the dilemma, I am happy with a design like this because my validation is encapsulated in individual objects which brings many advantages: easy unit test, easy to maintain, domain invariants are explicitly expressed using the Ubiquitous Language, easy to extend, validation logic is centralized and validators can be used together to enforce complex domain rules. And even when I know I am placing the validation of my entities outside of them (You could argue a code smell - Anemic Domain) but I think the trade-off is acceptable But there is one thing that I have not figured out how to implement it in a clean way. How should I use this components... Since they will be injected, they won’t fit naturally inside my domain entities, so basically I see two options: Pass the validators to each method of my entity Validate my objects externally (from the command handler) I am not happy with the option 1 so I would explain how I would do it with the option 2 class ChangeEmailCommandHandler : ICommandHandler<ChangeEmailCommand> { public void Execute(ChangeEmailCommand command) { private IEnumerable<IDomainInvariantValidator> validators; // here I would get the validators required for this command injected, and in here I would validate them, something like this using (var t = this.unitOfWork.BeginTransaction()) { var customer = this.unitOfWork.Get<Customer>(command.CustomerId); this.validators.ForEach(x =. x.IsValid(customer, command)); // here I know the command is valid // the call to ChangeEmail will fire domain events as needed customer.ChangeEmail(command.Email); t.Commit(); } } } Well this is it. Can you give me your thoughts about this or share your experiences with Domain entities validation EDIT I think it is not clear from my question, but the real problem is: Hiding the domain rules has serious implications in the future maintainability of the application, and also domain rules change often during the life-cycle of the app. Hence implementing them with this in mind would let us extend them easily. Now imagine in the future a rules engine is implemented, if the rules are encapsulated outside of the domain entities, this change would be easier to implement

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  • Load login shell inside user cronjob

    - by sa125
    I'm trying to run a rake task using a scheduled cronjob. My crontab looks something like this: 0 1 * * 1-7 /bin/bash -l -c "cd ~/jobs/rake && rake reports:create >> ~/jobs/logs/cron.log" Ruby on my account is provided by RVM, which is loaded via ~/.bashrc (before the no-interaction check): # load RVM env [[ -s $HOME/.rvm/scripts/rvm ]] && source $HOME/.rvm/scripts/rvm # If not running interactively, don't do anything [ -z "$PS1" ] && return # ... rest of logic Time and again, this task fails to run since RVM isn't loaded when the task is called (uses system's /usr/bin/ruby instead), and gem dependencies are missing. How can I make crontab load my shell environment before executing my scheduled jobs? thanks.

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  • What's the most unsound program you've had to maintain?

    - by Robert Rossney
    I periodically am called upon to do maintenance work on a system that was built by a real rocket surgeon. There's so much wrong with it that it's hard to know where to start. No, wait, I'll start at the beginning: in the early days of the project, the designer was told that the system would need to scale, and he'd read that a source of scalability problems was traffic between the application and database servers, so he made sure to minimize this traffic. How? By putting all of the application logic in SQL Server stored procedures. Seriously. The great bulk of the application functions by the HTML front end formulating XML messages. When the middle tier receives an XML message, it uses the document element's tag name as the name of the stored procedure it should call, and calls the SP, passing it the entire XML message as a parameter. It takes the XML message that the SP returns and returns it directly back to the front end. There is no other logic in the application tier. (There was some code in the middle tier to validate the incoming XML messages against a library of schemas. But I removed it, after ascertaining that 1) only a small handful of messages had corresponding schemas, 2) the messages didn't actually conform to these schemas, and 3) after validating the messages, if any errors were encountered, the method discarded them. "This fuse box is a real time-saver - it comes from the factory with pennies pre-installed!") I've seen software that does the wrong thing before. Lots of it. I've written quite a bit. But I've never seen anything like the steely-eyed determination to do the wrong thing, at every possible turn, that's embodied in the design and programming of this system. Well, at least he went with what he knew, right? Um. Apparently, what he knew was Access. And he didn't really understand Access. Or databases. Here's a common pattern in this code: SELECT @TestCodeID FROM TestCode WHERE TestCode = @TestCode SELECT @CountryID FROM Country WHERE CountryAbbr = @CountryAbbr SELECT Invoice.*, TestCode.*, Country.* FROM Invoice JOIN TestCode ON Invoice.TestCodeID = TestCode.ID JOIN Country ON Invoice.CountryID = Country.ID WHERE Invoice.TestCodeID = @TestCodeID AND Invoice.CountryID = @CountryID Okay, fine. You don't trust the query optimizer either. But how about this? (Originally, I was going to post this in What's the best comment in source code you have ever encountered? but I realized that there was so much more to write about than just this one comment, and things just got out of hand.) At the end of many of the utility stored procedures, you'll see code that looks like the following: -- Fix NULLs SET @TargetValue = ISNULL(@TargetValue, -9999) Yes, that code is doing exactly what you can't allow yourself to believe it's doing lest you be driven mad. If the variable contains a NULL, he's alerting the caller by changing its value to -9999. Here's how this number is commonly used: -- Get target value EXEC ap_GetTargetValue @Param1, @Param2, OUTPUT @TargetValue -- Check target value for NULL value IF @TargetValue = -9999 ... Really. For another dimension of this system, see the article on thedailywtf.com entitled I Think I'll Call Them "Transactions". I'm not making any of this up. I swear. I'm often reminded, when I work on this system, of Wolfgang Pauli's famous response to a student: "That isn't right. It isn't even wrong." This can't really be the very worst program ever. It's definitely the worst one I've worked

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  • Python: Memory usage and optimization when modifying lists

    - by xApple
    The problem My concern is the following: I am storing a relativity large dataset in a classical python list and in order to process the data I must iterate over the list several times, perform some operations on the elements, and often pop an item out of the list. It seems that deleting one item out of a Python list costs O(N) since Python has to copy all the items above the element at hand down one place. Furthermore, since the number of items to delete is approximately proportional to the number of elements in the list this results in an O(N^2) algorithm. I am hoping to find a solution that is cost effective (time and memory-wise). I have studied what I could find on the internet and have summarized my different options below. Which one is the best candidate ? Keeping a local index: while processingdata: index = 0 while index < len(somelist): item = somelist[index] dosomestuff(item) if somecondition(item): del somelist[index] else: index += 1 This is the original solution I came up with. Not only is this not very elegant, but I am hoping there is better way to do it that remains time and memory efficient. Walking the list backwards: while processingdata: for i in xrange(len(somelist) - 1, -1, -1): dosomestuff(item) if somecondition(somelist, i): somelist.pop(i) This avoids incrementing an index variable but ultimately has the same cost as the original version. It also breaks the logic of dosomestuff(item) that wishes to process them in the same order as they appear in the original list. Making a new list: while processingdata: for i, item in enumerate(somelist): dosomestuff(item) newlist = [] for item in somelist: if somecondition(item): newlist.append(item) somelist = newlist gc.collect() This is a very naive strategy for eliminating elements from a list and requires lots of memory since an almost full copy of the list must be made. Using list comprehensions: while processingdata: for i, item in enumerate(somelist): dosomestuff(item) somelist[:] = [x for x in somelist if somecondition(x)] This is very elegant but under-the-cover it walks the whole list one more time and must copy most of the elements in it. My intuition is that this operation probably costs more than the original del statement at least memory wise. Keep in mind that somelist can be huge and that any solution that will iterate through it only once per run will probably always win. Using the filter function: while processingdata: for i, item in enumerate(somelist): dosomestuff(item) somelist = filter(lambda x: not subtle_condition(x), somelist) This also creates a new list occupying lots of RAM. Using the itertools' filter function: from itertools import ifilterfalse while processingdata: for item in itertools.ifilterfalse(somecondtion, somelist): dosomestuff(item) This version of the filter call does not create a new list but will not call dosomestuff on every item breaking the logic of the algorithm. I am including this example only for the purpose of creating an exhaustive list. Moving items up the list while walking while processingdata: index = 0 for item in somelist: dosomestuff(item) if not somecondition(item): somelist[index] = item index += 1 del somelist[index:] This is a subtle method that seems cost effective. I think it will move each item (or the pointer to each item ?) exactly once resulting in an O(N) algorithm. Finally, I hope Python will be intelligent enough to resize the list at the end without allocating memory for a new copy of the list. Not sure though. Abandoning Python lists: class Doubly_Linked_List: def __init__(self): self.first = None self.last = None self.n = 0 def __len__(self): return self.n def __iter__(self): return DLLIter(self) def iterator(self): return self.__iter__() def append(self, x): x = DLLElement(x) x.next = None if self.last is None: x.prev = None self.last = x self.first = x self.n = 1 else: x.prev = self.last x.prev.next = x self.last = x self.n += 1 class DLLElement: def __init__(self, x): self.next = None self.data = x self.prev = None class DLLIter: etc... This type of object resembles a python list in a limited way. However, deletion of an element is guaranteed O(1). I would not like to go here since this would require massive amounts of code refactoring almost everywhere.

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  • Prevent Firefox from going to first search result

    - by Dejan
    When I type some terms in the address bar (not the search box!) and hit enter, Firefox searches for those terms on Google, and, depending on some logic either takes me to the search results page or takes me to the first search result. Now, I want it to always take me to the search results page (like Chrome does). Is this possible? And, yes, I am aware that the search box does exactly that, but I'm using it for some other search engine. So, another solution would be to add additional search box, that can also work for me.

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  • Changing Servers - Redirect to new IP = No Downtime?

    - by Denis Pshenov
    I am changing servers of my website. The IP of old server cannot be moved to the new one. To have no downtime I am planing to do the following, please someone confirm it will work: Setup the new server and listen on the new IP Old server redirect all traffic to the new IP Change DNS records to point to the new IP My logic tells me that when I redirect to the new IP from my old box, the user will not see the domain name in the browser but will see the new IP. Is there a way to redirect to the new IP and send along the HOSTNAME with it so that the user will see the domain name in the browser? Im doing this because the site is in constant use and simply changing DNS settings won't do as database won't be synced between the new and old servers during propagation.

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  • I'm trying to handle the updates on 2 related tables in one DetailsView using Jquery and Linq, and h

    - by Ben Reisner
    Given two related tables (reports, report_fields) where there can be many report_fields entries for each reports entry, I need to allow the user to enter new report_fields, delete existing report_fields, and re-arrange the order. Currently I am using a DetailsView to handle the editing of the reports. I added some logic to handle report_fields, and currently it allows you to succesfully re-arrange the order, but i'm a little stumped as to the best way to add new items, or delete existing items. The basic logic I have is that each report_fields is represented by a . It has a description as the text, and a field for each field in the report_fields table. I use JQuery Sortable to allow the user to re-arrange the LIs. Abbreviated Create Table Statements:(foreign key constraint ignored for brevity) create table report( id integer primary key identity, reportname varchar(250) ) create table report_fields( id integer primary key identity, reportID integer, keyname integer, keyvalue integer, field_order integer ) My abbreviated markup: <asp:DetailsView ...> ... <asp:TemplateField HeaderText="Fields"> <EditItemTemplate> <ul class="MySortable"> <asp:Repeater ID="Repeater1" runat="server" DataSource='<%# Eval("report_fields") %>'> <ItemTemplate> <li> <%# Eval("keyname") %>: <%# Eval("keyvalue") %> <input type="hidden" name="keyname[]" value='<%# Eval("keyname") %>' /> <input type="hidden" name="keyvalue[]" value='<%# Eval("keyvalue") %>' /> </li> </ItemTemplate> </asp:Repeater> </ul> </EditItemTemplate> </asp:TemplateField> </asp:DetailsView> <asp:LinqDataSource ID="LinqDataSource2" onupdating="LinqDataSource2_Updating" table=reports ... /> $(function() { $(".MySortable").sortable({ placeholder: 'MySortable-highlight' }).disableSelection(); }); Code Behind Class: public partial class Administration_AddEditReport protected void LinqDataSource2_Updating(object sender, LinqDataSourceUpdateEventArgs e) { report r = (report)e.NewObject; MyDataContext dc = new MyDataContext(); var fields = from f in dc.report_fields where f.reportID == r.id select f; dc.report_fields.DeleteAllOnSubmit(fields); NameValueCollection nvc = Request.Params; string[] keyname = nvc["keyname[]"].Split(','); string[] keyvalue = nvc["keyvalue[]"].Split(','); for (int i = 0; i < keyname.Length; i++) { report_field rf = new report_field(); rf.reportID = r.id; rf.keyname = keyname[i]; rf.keyvalue = keyvalue[i]; rf.field_order = i; dc.report_fields.InsertOnSubmit(rf); } dc.SubmitChanges(); } }

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  • ICQ offline messages (do not show up)

    - by Nils Riedemann
    Hi there, I have a weird problem with offline messages: I use Adium on 2 Macs (home and office) and Beejive (iPhone) for connecting to ICQ and other protocols. When someone sends me an offline messages I expect them to show up the next time I login with any of my 3 devices. But thats not the case. Recently some show up at the office, some at home and some on my iPhone – couldnt figure out any logic behind it, seems rather random. I thought for a while that it depends on the last device i have been logged in with. But thats not the case either. A friend can send me offline Messages during the weekend, i can login with my Mac at home or iPhone, yet in some cases it only shows up when logging in from office. Weird. It really freaks me out – and no, i can't make 'em go to jabber or the like. Anyone experiencing a similar problem?

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  • wsgi - narrow user permissions.

    - by Tomasz Wysocki
    I have following Apache configuration and my application is working fine: <VirtualHost *:80> ServerName ig-test.example.com WSGIScriptAlias / /home/ig-test/src/repository/django.wsgi WSGIDaemonProcess ig-test user=ig-test </VirtualHost> But I want to protect my files from other users, so I do: chown ig-test /home/ig-test/ -R chmod og-rwx /home/ig-test/ -R And application stops working: (13)Permission denied: /home/ig-test/.htaccess pcfg_openfile: unable to check htaccess file, ensure it is readable Is it possible to achieve what i'm doing with wsgi? If I have to give read permissions to some files it will be fine. But there are files I have to protect (like file with DB configuration or business logic of application).

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  • Is this a right way to use NHibernate?

    - by Venemo
    I spent the rest of the evening reading StackOverflow questions and also some blog entries and links about the subject. All of them turned out to be very helpful, but I still feel that they don't really answer my question. So, I'm developing a simple web application. I'd like to create a reusable data access layer which I can later reuse in other solutions. 99% of these will be web applications. This seems to be a good excuse for me to learn NHibernate and some of the patterns around it. My goals are the following: I don't want the business logic layer to know ANYTHING about the inner workings of the database, nor NHibernate itself. I want the business logic layer to have the least possible number of assumptions about the data access layer. I want the data access layer as simplistic and easy-to-use as possible. This is going to be a simple project, so I don't want to overcomplicate anything. I want the data access layer to be as non-intrusive as possible. Will all this in mind, I decided to use the popular repository pattern. I read about this subject on this site and on various dev blogs, and I heard some stuff about the unit of work pattern. I also looked around and checked out various implementations. (Including FubuMVC contrib, and SharpArchitecture, and stuff on some blogs.) I found out that most of these operate with the same principle: They create a "unit of work" which is instantiated when a repository is instantiated, they start a transaction, do stuff, and commit, and then start all over again. So, only one ISession per Repository and that's it. Then the client code needs to instantiate a repository, do stuff with it, and then dispose. This usage pattern doesn't meet my need of being as simplistic as possible, so I began thinking about something else. I found out that NHibernate already has something which makes custom "unit of work" implementations unnecessary, and that is the CurrentSessionContext class. If I configure the session context correctly, and do the clean up when necessary, I'm good to go. So, I came up with this: I have a static class called NHibernateHelper. Firstly, it has a static property called CurrentSessionFactory, which upon first call, instantiates a session factory and stores it in a static field. (One ISessionFactory per one AppDomain is good enough.) Then, more importantly, it has a CurrentSession static property, which checks if there is an ISession bound to the current session context, and if not, creates one, and binds it, and it returns with the ISession bound to the current session context. Because it will be used mostly with WebSessionContext (so, one ISession per HttpRequest, although for the unit tests, I configured ThreadStaticSessionContext), it should work seamlessly. And after creating and binding an ISession, it hooks an event handler to the HttpContext.Current.ApplicationInstance.EndRequest event, which takes care of cleaning up the ISession after the request ends. (Of course, it only does this if it is really running in a web environment.) So, with all this set up, the NHibernateHelper will always be able to return a valid ISession, so there is no need to instantiate a Repository instance for the "unit of work" to operate properly. Instead, the Repository is a static class which operates with the ISession from the NHibernateHelper.CurrentSession property, and exposes some functionality through that. I'm curious, what do you think about this? Is it a valid way of thinking, or am I completely off track here?

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  • When a python process is killed on OSX, why doesn't it kill the child processes?

    - by Hugh
    I found myself getting very confused a while back by some changes that I found when moving Python scripts from Linux over to OSX... On Linux, if a python script has called os.system(), and the calling process is killed, the called process will be killed at the same time. On OSX, however, if the main process is killed, anything that it launched is left behind. Is there something somewhere in OSX/Python where I can change this behaviour? This is causing problems on our render farm, where the processes can be killed from the management GUI, but the top level process is really just a wrapper, so, while the render farm management might think that the process has gone and the machine is freed up for another task, the actual processor-intensive task is still running, which can lead to huge blockages. I know that I could write more logic to catch the kill signal and pass it on to the child processes, but I was hoping that it might be something that could be enabled at a lower level.

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  • How to get two seperate remote domain controllers with same IP to work?

    - by Mr. Mister
    Hi, I have a VPN setup between multiple locations. Between each location and the central point (me), is a trust between our domain controllers. It all works great.. A new location wants to join, but their AD controller is using an IP address that is already in use by another AD in a separate location. Neither locations can change their IP addresses, but apparently there is a NAT rule that could be used to allow communication between each AD controller? The central site has a Cisco 5510 firewall which could perform the NAT, but I am unsure of the logic behind the NAT rule. Is anyone able to explain or help out? Thanks.

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  • Multi-threaded .NET application blocks during file I/O when protected by Themida

    - by Erik Jensen
    As the title says I have a .NET application that is the GUI which uses multiple threads to perform separate file I/O and notice that the threads occasionally block when the application is protected by Themida. One thread is devoted to reading from serial COM port and another thread is devoted to copying files. What I experience is occasionally when the file copy thread encounters a network delay, it will block the other thread that is reading from the serial port. In addition to slow network (which can be transient), I can cause the problem to happen more frequently by making a PathFileExists call to a bad path e.g. PathFileExists("\\\\BadPath\\file.txt"); The COM port reading function will block during the call to ReadFile. This only happens when the application is protected by Themida. I have tried under WinXP, Win7, and Server 2012. In a streamlined test project, if I replace the .NET application with a MFC unmanaged application and still utilize the same threads I see no issue even when protected with Themida. I have contacted Oreans support and here is their response: The way that a .NET application is protected is very different from a native application. To protect a .NET application, we need to hook most of the file access APIs in order to "cheat" the .NET Framework that the application is protected. I guess that those special hooks (on CreateFile, ReadFile...) are delaying a bit the execution in your application and the problem appears. We did a test making those hooks as light as possible (with minimum code on them) but the problem still appeared in your application. The rest of software protectors that we tried (like Enigma, Molebox...) also use a similar hooking approach as it's the only way to make the .NET packed file to work. If those hooks are not present, the .NET Framework will abort execution as it will see that the original file was tampered (due to all Microsoft checks on .NET files) Those hooks are not present in a native application, that's why it should be working fine on your native application. Oreans support tried other software protectors such as Enigma Protector, Engima VirtualBox, and Molebox and all exhibit the exact same problem. What I have found as a work around is to separate out the file copy logic (where the file exists call is being made) to be performed in a completely separate process. I have experimented with converting the thread functions from unmanaged C++ to VB.NET equivalents (PathFileExists - System.IO.File.Exists and CreateFile/ReadFile - System.IO.Ports.SerialPort.Open/Read) and still see the same serial port read blocked when the file check or copy call is delayed. I have also tried setting the ReadFile to work asynchronously but that had no effect. I believe I am dealing with some low-level windows layer that no matter the language it exhibits a block on a shared resource -- and only when the application is executing under a single .NET process protected by Themida which evidently installs some hooks to allow .NET execution. At this time converting the entire application away from .NET is not an option. Nor is separating out the file copy logic to a separate task. I am wondering if anyone else has more knowledge of how a file operation can block another thread reading from a system port. I have included here example applications that show the problem: https://db.tt/cNMYfEIg - VB.NET https://db.tt/Y2lnTqw7 - MFC They are Visual Studio 2010 solutions. When running the themida protected exe, you can see when the FileThread counter pauses (executing the File.Exists call) while the ReadThread counter also pauses. When running non-protected visual studio output exe, the ReadThread counter does not pause which is how we expect it to function. Thanks!

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  • Can I make ssh tell me which control file it would use for multiplexing?

    - by Ryan Thompson
    I am using the following options in my ~/.ssh/config in order to enable connection multiplexing: ControlMaster auto ControlPath ~/.ssh/control/master-%r@%h:%p However, this has the annoying problem that the first shell to connect to a particular server must be the last to disconnect, because it is the master connection that all the other connections are using. So if you log out of the master, it appears to just hang. To solve this, I would like to wrap ssh with a script that checks if the control master file exists, and if not, starts a master ssh process in the background. Then it would start a slave ssh session. In order to accomplish this, my script would have to determine the path to the control file that ssh would use. This would entail parsing the ssh command line options and config files and implementing the logic for determining the ControlPath. Is there any way to just ask ssh what path it would use, so I can check it?

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  • Unnecessary Java context switches

    - by Paul Morrison
    I have a network of Java Threads (Flow-Based Programming) communicating via fixed-capacity channels - running under WindowsXP. What we expected, based on our experience with "green" threads (non-preemptive), would be that threads would switch context less often (thus reducing CPU time) if the channels were made bigger. However, we found that increasing channel size does not make any difference to the run time. What seems to be happening is that Java decides to switch threads even though channels aren't full or empty (i.e. even though a thread doesn't have to suspend), which costs CPU time for no apparent advantage. Also changing Thread priorities doesn't make any observable difference. My question is whether there is some way of persuading Java not to make unnecessary context switches, but hold off switching until it is really necessary to switch threads - is there some way of changing Java's dispatching logic? Or is it reacting to something I didn't pay attention to?! Or are there other asynchronism mechanisms, e.g. Thread factories, Runnable(s), maybe even daemons (!). The answer appears to be non-obvious, as so far none of my correspondents has come up with an answer (including most recently two CS profs). Or maybe I'm missing something that's so obvious that people can't imagine my not knowing it... I've added the send and receive code here - not very elegant, but it seems to work...;-) In case you are wondering, I thought the goLock logic in 'send' might be causing the problem, but removing it temporarily didn't make any difference. I have added the code for send and receive... public synchronized Packet receive() { if (isDrained()) { return null; } while (isEmpty()) { try { wait(); } catch (InterruptedException e) { close(); return null; } if (isDrained()) { return null; } } if (isDrained()) { return null; } if (isFull()) { notifyAll(); // notify other components waiting to send } Packet packet = array[receivePtr]; array[receivePtr] = null; receivePtr = (receivePtr + 1) % array.length; //notifyAll(); // only needed if it was full usedSlots--; packet.setOwner(receiver); if (null == packet.getContent()) { traceFuncs("Received null packet"); } else { traceFuncs("Received: " + packet.toString()); } return packet; } synchronized boolean send(final Packet packet, final OutputPort op) { sender = op.sender; if (isClosed()) { return false; } while (isFull()) { try { wait(); } catch (InterruptedException e) { indicateOneSenderClosed(); return false; } sender = op.sender; } if (isClosed()) { return false; } try { receiver.goLock.lockInterruptibly(); } catch (InterruptedException ex) { return false; } try { packet.clearOwner(); array[sendPtr] = packet; sendPtr = (sendPtr + 1) % array.length; usedSlots++; // move this to here if (receiver.getStatus() == StatusValues.DORMANT || receiver.getStatus() == StatusValues.NOT_STARTED) { receiver.activate(); // start or wake up if necessary } else { notifyAll(); // notify receiver // other components waiting to send to this connection may also get // notified, // but this is handled by while statement } sender = null; Component.network.active = true; } finally { receiver.goLock.unlock(); } return true; }

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  • use network drives as mount points during installation?

    - by ajsie
    is it possible to use network storage locations as mount points during installation? cause i want to separate system (ubuntu) with data (personal files). eg. if i have 5 computers i don't want to recreate /home/david 5 times. so i want to mount networkdrive/home to /home in local ubuntu server. so ALL users home folders could be used and maybe also networkdrive/projects to /projects. in that way its ok if i by accident repartitioned the local ubuntu server cause all data is not there on that server, but in the data server. is separating "data" from "logic" good in this case? and is it possible? what protocol should i use for the mapping over internet? (maybe the server is in Sweden, and the data is in Norway). thanks.

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  • One quarter of screen corrupted on MacBook Pro

    - by danyal
    I have a problem with my MacBook Pro's screen - here's a video: http://yfrog.com/4wm63z For those who prefer words, if you divide the screen vertically into 4 columns, the second column is corrupted (flickering, and discoloured, usually with yellow). I took it to an Apple store and they said it could be the screen or the logic board, neither of which will be cheap to replace. However, occasionally this problem will completely go away. So before I part with my cash, or decide to turn this into an overpriced media center for my TV... could the problem be a loose cable, or something else cheaper to fix?

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  • WPF BackgroundWorker Execution

    - by Sanju
    Hi All, I've been programming C# for a while now (I'm a Computer Science major), and have never had to implement threading. I am currently building an application for a client that requires threading for a series of operations. Due to the nature of the client/provider agreement, I cannot release the source I am working with. The code that I have posted is in a general form. Pretty much the basic idea of what I am implementing, excluding the content specific source. The first Snippet demonstrates my basic structure, The Progress class is a custom progress window that is displayed as a dialog to prevent user UI interaction. I am currently using the code to complete database calls based on a collection of objects in another area of the application code. For example, I have a collection of "Objects" of one of my custom classes, that I perform these database calls on or on behalf of. My current set up works just fine when I call the "GeneralizedFunction" one and only one time. What I need to do is call this function once for every object in the collection. I was attempting to use a foreach loop to iterate through the collection, then I tried a for loop. For both loops, the result was the same. The Async operation performs exactly as desired for the first item in the collection. This, however, is the only one it works for. For each subsequent item, the progress box (my custom window) displays and immediately closes. In terms of the database calls, the calls for the first item in the collection are the only ones that successfully complete. All others aren't attempted. I've tried everything that I know and don't know to do, but I just cannot seem to get it to work. How can I get this to work for my entire collection? Any and all help is very greatly appreciated. Progress progress; BackgroundWorker worker; // Cancel the current process private void CancelProcess(object sender, EventArgs e) { worker.CancelAsync(); } // The main process ... "Generalized" private void GeneralizedFunction() { progress = new Progress(); progress.Cancel += CancelProcess; progress.Owner = this; Dispatcher pDispatcher = progress.Dispatcher; worker = new BackgroundWorker(); worker.WorkerSupportsCancellation = true; object[] workArgs = { arg1, arg2, arg3}; worker.DoWork += delegate(object s, DoWorkEventArgs args) { /* All main logic here */ foreach(Class ClassObject in ClassObjectCollection) { //Some more logic here UpdateProgressDelegate update = new UpdateProgressDelegate(updateProgress); pDispatcher.BeginInvoke(update, arg1,arg2,arg3); Thread.Sleep(1000); } }; worker.RunWorkerCompleted += delegate(object s, RunWorkerCompletedEventArgs args) { progress.Close(); }; worker.RunWorkerAsync(workArgs); progress.ShowDialog(); } public delegate void UpdateProgressDelegate(arg1,arg2,arg3); private void updateProgress(arg1,arg2,arg3) { //Update progress }

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  • Ubuntu 10.04 recognizing USB 2.0 external HD as USB 1.1

    - by btucker
    When I connect the USB 2.0 drive I see this: usb 1-4.3: new full speed USB device using ohci_hcd and address 5 so I know it's getting seen as USB 1.1. usb-devices shows that it really is USB 2.0 and connected to a USB 2.0 hub: T: Bus=01 Lev=01 Prnt=01 Port=03 Cnt=01 Dev#= 2 Spd=12 MxCh= 4 D: Ver= 2.00 Cls=09(hub ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=05e3 ProdID=0608 Rev=77.61 S: Product=USB2.0 Hub C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub T: Bus=01 Lev=02 Prnt=02 Port=01 Cnt=01 Dev#= 4 Spd=12 MxCh= 0 D: Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=13fd ProdID=1340 Rev=02.10 S: Manufacturer=Generic S: Product=External C: #Ifs= 1 Cfg#= 1 Atr=c0 MxPwr=2mA I: If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage It seems the problem is that root hub is: T: Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= 1 Spd=12 MxCh=10 D: Ver= 1.10 Cls=09(hub ) Sub=00 Prot=00 MxPS=64 #Cfgs= 1 P: Vendor=1d6b ProdID=0001 Rev=02.06 S: Manufacturer=Linux 2.6.32-25-server ohci_hcd S: Product=OHCI Host Controller S: SerialNumber=0000:00:02.0 C: #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=0mA I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00 Driver=hub And there's no mention of ehci_hcd. lsusb -t gives me: /: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=ohci_hcd/10p, 12M |__ Port 4: Dev 2, If 0, Class=hub, Driver=hub/4p, 12M |__ Port 2: Dev 4, If 0, Class=stor., Driver=usb-storage, 12M |__ Port 3: Dev 5, If 0, Class=stor., Driver=usb-storage, 12M |__ Port 6: Dev 3, If 0, Class=stor., Driver=usb-storage, 12M It seems like I'm missing something which would allow the OS to see USB 2.0 devices. Can anyone point me in the right direction? EDIT Full lsusb -v output: Bus 001 Device 005: ID 13fd:1340 Initio Corporation Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x13fd Initio Corporation idProduct 0x1340 bcdDevice 2.10 iManufacturer 1 Generic iProduct 2 External iSerial 3 57442D574341595930323337 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xc0 Self Powered MaxPower 2mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 8 Mass Storage bInterfaceSubClass 6 SCSI bInterfaceProtocol 80 Bulk (Zip) iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0040 1x 64 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x02 EP 2 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0040 1x 64 bytes bInterval 0 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0001 Self Powered Bus 001 Device 002: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x05e3 Genesys Logic, Inc. idProduct 0x0608 USB-2.0 4-Port HUB bcdDevice 77.61 iManufacturer 0 iProduct 1 USB2.0 Hub iSerial 0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 100mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0001 1x 1 bytes bInterval 255 Hub Descriptor: bLength 9 bDescriptorType 41 nNbrPorts 4 wHubCharacteristic 0x00e0 Ganged power switching Ganged overcurrent protection Port indicators bPwrOn2PwrGood 50 * 2 milli seconds bHubContrCurrent 100 milli Ampere DeviceRemovable 0x00 PortPwrCtrlMask 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0103 power enable connect Port 3: 0000.0103 power enable connect Port 4: 0000.0100 power Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 1 Single TT bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0001 Self Powered Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 1.10 bDeviceClass 9 Hub bDeviceSubClass 0 Unused bDeviceProtocol 0 Full speed (or root) hub bMaxPacketSize0 64 idVendor 0x1d6b Linux Foundation idProduct 0x0001 1.1 root hub bcdDevice 2.06 iManufacturer 3 Linux 2.6.32-25-server ohci_hcd iProduct 2 OHCI Host Controller iSerial 1 0000:00:02.0 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 25 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0xe0 Self Powered Remote Wakeup MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 1 bInterfaceClass 9 Hub bInterfaceSubClass 0 Unused bInterfaceProtocol 0 Full speed (or root) hub iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0002 1x 2 bytes bInterval 255 Hub Descriptor: bLength 11 bDescriptorType 41 nNbrPorts 10 wHubCharacteristic 0x0002 No power switching (usb 1.0) Ganged overcurrent protection bPwrOn2PwrGood 1 * 2 milli seconds bHubContrCurrent 0 milli Ampere DeviceRemovable 0x00 0x00 PortPwrCtrlMask 0xff 0xff Hub Port Status: Port 1: 0000.0100 power Port 2: 0000.0100 power Port 3: 0000.0100 power Port 4: 0000.0103 power enable connect Port 5: 0000.0100 power Port 6: 0000.0103 power enable connect Port 7: 0000.0100 power Port 8: 0000.0100 power Port 9: 0000.0100 power Port 10: 0000.0100 power Device Status: 0x0003 Self Powered Remote Wakeup Enabled

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  • Zabbix - Some of the monitored items dont get refreshd. how to find the reason?

    - by Niro
    I'm experiencing a strange issue with Zabbix monitoring a MySQL server. Most of the data from the server such as MySQL queries per second and MySQL uptime , Buffers memory etc. update nicely while some data like CPU iowait time (avg1) , Host local time ,MySQL number of threads and other items which were monitored in the past has last check time of about a week ago. I can't find any logic in this, for example Mysql number of threads and Mysql queries per second are obtained in a similar way so it does not make sense one of them is monitored and one is not. Please help- how can I fix this?

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  • Php template caching design

    - by Thomas
    Hello to all, I want to include caching in my app design. Caching templates for starters. The design I have used so far is very modular. I have created an ORM implementation for all my tables and each table is represented by the corresponding class. All the requests are handled by one controller which routes them to the appropriate webmethod functions. I am using a template class for handling UI parts. What I have in mind for caching includes the implementation of a separate Cache class for handling caching with the flexibility to either store in files, apc or memcache. Right now I am testing with file caching. Some thoughts Should I include the logic of checking for cached versions in the Template class or in the webmethods which handle the incoming requests and which eventually call the Template class. In the first case, things are pretty simple as I will not have to change anything more than pass the template class an extra argument (whether to load from cache or not). In the second case however, I am thinking of checking for a cached version immediately in the webmethod and if found return it. This will save all the processing done until the logic reaches the template (first case senario). Both senarios however, rely on an accurate mechanism of invalidating caches, which brings as to Invalidating caches As I see it (and you can add your input freely) a template cached file, becomes invalidate if: a. the expiration set, is reached. b. the template file itself is updated (ie by the developer when adding a new line) c. the webmethod that handles the request changes (ie the developer adds/deletes something in the code) d. content coming from the db and ending in the template file is modified I am thinking of storing a json encoded array inside the cached file. The first value will be the expiration timestamp of the cache. The second value will be the modification time of the php file with the code handling the request (to cope with option c above) The third will be the content itself The validation process I am considering, according to the above senarios, is: a. If the expiration of the cached file (stored in the array) is reached, delete the cache file b. if the cached file's mod time is smaller than the template's skeleton file mod time, delete the cached file c. if the mod time of the php file is greated than the one stored in the cache, delete the cached file. d. This is tricky. In the ORM implementation I ahve added event handlers (which fire when adding, updating, deleting objects). I could delete the cache file every time an object thatprovides content to the template, is modified. The problem is how to keep track which cached files correpond to each schema object. Take this example, a user has his shortprofile page and a full profile page (2 templates) These templates can be cached. Now, every time the user modifies his profile, the event handler would need to know which templates or cached files correspond to the User, so that these files can be deleted. I could store them in the db but I am looking for a beter approach

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  • Puppet causes endless restarts of CUPS (how does one prevent this)

    - by Purfideas
    Hi! It makes sense, and is in fact suggested on this site, to have a critical file change trigger a service restart with puppet meta-parameters (such as notify or subscribe). For example: ## file definition for printers.conf file { "/etc/cups/printers.conf": [snip], source => "puppet:///module/etc/cups/printers.conf" } ## service definition for sshd service { 'cups': ensure => running, subscribe => File['/etc/cups/printers.conf'] } But in the case of CUPS, this triggers and endless loop of restarts; the logic works like this: Change puppetmaster's version of /etc/cups/printers.conf puppetmaster pushes new version to client, triggering cups restart cupsd restart insists on putting its own time stamp at the top of printers.conf, 'Written by cupsd...' This change will be seen as out of date, so after runinterval, we return to (1). Is there a way to suppress cupsd's need to time stamp the file? Or is there a puppet trick that could help here? Thanks!

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  • I have to shard a mysql database. I want to start with 12 shards on 2 machines. What is the best w

    - by Tim
    All tables are InnoDb. I would rather not use mysqldump, because the shard sizes will be about 200 GB (about 700 million rows), and that will take too long. I was hoping to just stop mysql for an hour, copy the data files to a new machine, and start back up. But you can't do this with InnoDb, as some data is in the shared tablespace. Even if I have the innodb_file_per_table option set. This is not a website, but a custom application, used by tens of thousands right now, so uptime and performance are important. I suppose I could add logic into my server application to allow for gradual rebalancing / moving of a shard. Does anyone have a better idea?

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  • Software that supports ATA Secure Erase Command

    - by vy32
    We have a lot of drives that need to be sanitized. NIST SP 800-88 recommends software that uses the ATA Secure Erase command. That's apparently the only way to be sure that the drive is properly wiped, due to bad-block remapping and such. I know that this functionality is available in hdparm. The problem with that approach is that it is inconsistent on multiple platforms, occasionally times out, doesn't have error-checking logic, and doesn't check the resulting drive to make sure that it has, in fact, been erased. So a proper program might use hdparm, but hdparm by itself isn't an answer. I'm looking for open source software that implements ATA Secure Erase. Ideally it will be a bootable disk image like DBAN, but it will use the ATA command.

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