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  • How to merge objects in php ?

    - by The Devil
    Hey everybody, I'm currently re-writing a class which handles xml files. Depending on the xml file and it's structure I sometimes need to merge objects. Lets say once I have this: <page name="a title"/> And another time I have this: <page name="a title"> <permission>administrator</permission> </page> Before, I needed only the attributes from the "page" element. That's why a lot of my code expects an object containing only the attributes ($loadedXml-attributes()). Now there are xml files in which the <permission> element is required. I did manage to merge the objects (though not as I wanted) but I can't get to access one of them (most probably it's something I'm missing). To merge my objects I used this code: (object) array_merge( (array) $loadedXml->attributes(), (array) $loadedXml->children() ); This is what I get from print_r(): stdClass Object ( [@attributes] => Array ( [name] => a title ) [permission] => Array ( [0] => administrator ) ) So now my question is how to access the @attributes method ? Thanks in advance, The Devil

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  • SQL Server 2005 Import from Excel

    - by user327045
    I'd like to know what my best option would be to import data from an excel file on a weekly or monthly basis. At first, I thought I would use SSIS, but after much struggle with seemingly simple tasks, I'm starting to rethink my plan. Would it be better/easier to just write the SQL by hand or use the services of an SSIS package? The basic process will be as follows: A separate process will download an .xls file to a local fileshare. The xls file will have a filename like: 'myfilename MON YY'. I will need to read the month and year from the the filename, reformat it to a sql date and then query a DimDate table to find the corresponding date key. For each row (after the first 2 header rows), insert the data with the date key, unless the row is a total row, then ignore. Here are some of the issues I've been encountering with SSIS: I can parse the date string from a flat file datasource, but can't seem to do it with an excel data source. Also, once parsed, i cannot seem to convert the string to a date in order to perform the lookup for the date key. For example, I want to do something like this: select DateKey from DimDate where ActualDate = convert(datetime, '01-' + 'JAN-10', 120) but i don't think it is possible to use the 'convert' or 'datetime' keywords in an expression builder. I have been also unable to find where I can edit the SQL to ignore the first 2 rows of data. I'm very skeptical of using SSIS because it seems like a Kludgy way of doing something that can probably be accomplished more efficiently writing the SQL yourself, but I may be forced to use SSIS. Thoughts?

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  • Twitter api - no more than 150 requests per hour....

    - by RenegadeAndy
    Hi. I am writing a twitter app using jtwitter - and its running inside a server inside my work. Anyway - whenever i run it from work it returns the error below and I am only making a couple requests per hour: HTTP/1.1 400 Bad Request {"request":"/1/statuses/user_timeline.json?count=6&id=cicsdemo&","error":"Rate limit exceeded. Clients may not make more than 150 requests per hour."} ] 2010-06-03 18:44:49 zero.timer.TimerTask::run Thread-3 SEVERE [ CWPZA3100E: Exception during processing for timer task, "twitterTimer". Exception: java.lang.ClassCastException: winterwell.jtwitter.Twitter$Status incompatible with java.lang.String ] I run the same code from home - its fine. So obviously at some point twitter thinks our work is all coming from one direct IP - which is why its hitting a limit which it shouldnt. Do I have any choice or workaround - can i make the limit be counted from my direct machine IP - or to my account instead of IP? Can i use a proxy? Has any body else had this problem and solved it?! Before anyone asks the APP must live inside my work - it cannot run anywhere else! Cheers, Andy

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  • Generic callbacks

    - by bobobobo
    Extends So, I'm trying to learn template metaprogramming better and I figure this is a good exercise for it. I'm trying to write code that can callback a function with any number of arguments I like passed to it. // First function to call int add( int x, int y ) ; // Second function to call double square( double x ) ; // Third func to call void go() ; The callback creation code should look like: // Write a callback object that // will be executed after 42ms for "add" Callback<int, int, int> c1 ; c1.func = add ; c1.args.push_back( 2 ); // these are the 2 args c1.args.push_back( 5 ); // to pass to the "add" function // when it is called Callback<double, double> c2 ; c2.func = square ; c2.args.push_back( 52.2 ) ; What I'm thinking is, using template metaprogramming I want to be able to declare callbacks like, write a struct like this (please keep in mind this is VERY PSEUDOcode) <TEMPLATING ACTION <<ANY NUMBER OF TYPES GO HERE>> > struct Callback { double execTime ; // when to execute TYPE1 (*func)( TYPE2 a, TYPE3 b ) ; void* argList ; // a stored list of arguments // to plug in when it is time to call __func__ } ; So for when called with Callback<int, int, int> c1 ; You would automatically get constructed for you by < HARDCORE TEMPLATING ACTION > a struct like struct Callback { double execTime ; // when to execute int (*func)( int a, int b ) ; void* argList ; // this would still be void*, // but I somehow need to remember // the types of the args.. } ; Any pointers in the right direction to get started on writing this?

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  • managing html rich text selections

    - by swami
    Hi, I am writing a component for a web app which will display some html, and let me capture and manipulate the selection boundaries (of the text selected by the user). I have done this successfully (for Mozilla) with a simple div element using window.getSelection(). However, the browser selection API is different for IE. If I were to use a textarea instead (for interacting with the selection api), is there a uniform API across the browsers? Then I would need to overlay a DIV on top of this to display the styled text, and presumably I'd need to manage the cursor etc... Basically I want a rich text editor - but without editing. Does anyone have any advice on the best way to go about this, which is quick, simple and cross browser compatible. I don't want to spend ages reinventing the wheel... (If anyone's interested - this is for an online xml editor. I capture the users selection on a html version of the xml doc and then send the selection offsets info to the server, where the real xml doc gets marked up). Kind Regards Swami

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  • Implementing list position locator in C++?

    - by jfrazier
    I am writing a basic Graph API in C++ (I know libraries already exist, but I am doing it for the practice/experience). The structure is basically that of an adjacency list representation. So there are Vertex objects and Edge objects, and the Graph class contains: list<Vertex *> vertexList list<Edge *> edgeList Each Edge object has two Vertex* members representing its endpoints, and each Vertex object has a list of Edge* members representing the edges incident to the Vertex. All this is quite standard, but here is my problem. I want to be able to implement deletion of Edges and Vertices in constant time, so for example each Vertex object should have a Locator member that points to the position of its Vertex* in the vertexList. The way I first implemented this was by saving a list::iterator, as follows: vertexList.push_back(v); v->locator = --vertexList.end(); Then if I need to delete this vertex later, then rather than searching the whole vertexList for its pointer, I can call: vertexList.erase(v->locator); This works fine at first, but it seems that if enough changes (deletions) are made to the list, the iterators will become out-of-date and I get all sorts of iterator errors at runtime. This seems strange for a linked list, because it doesn't seem like you should ever need to re-allocate the remaining members of the list after deletions, but maybe the STL does this to optimize by keeping memory somewhat contiguous? In any case, I would appreciate it if anyone has any insight as to why this happens. Is there a standard way in C++ to implement a locator that will keep track of an element's position in a list without becoming obsolete? Much thanks, Jeff

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  • best practice - loging events (general) and changes (database)

    - by b0x0rz
    need help with logging all activities on a site as well as database changes. requirements: * should be in database * should be easily searchable by initiator (user name / session id), event (activity type) and event parameters i can think of a database design but either it involves a lot of tables (one per event) so i can log each of the parameters of an event in a separate field OR it involves one table with generic fields (7 int numeric and 7 text types) and log everything in one table with event type field determining what parameter got written where (and hoping that i don't need more than 7 fields of a certain type, or 8 or 9 or whatever number i choose)... example of entries (the usual things): [username] login failed @datetime [username] login successful @datetime [username] changed password @datetime, estimated security of password [low/ok/high/perfect] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] changed profile name from [old name] to [new name] @datetime [username] verified name with [credit card type] credit card @datetime datbase table [table name] purged of old entries @datetime etc... so anyone dealt with this before? any best practices / links you can share? i've seen it done with the generic solution mentioned above, but somehow that goes against what i learned from database design, but as you can see the sheer number of events that need to be trackable (each user will be able to see this info) is giving me headaches, BUT i do LOVE the one event per table solution more than the generic one. any thoughts? edit: also, is there maybe an authoritative list of such (likely) events somewhere? thnx stack overflow says: the question you're asking appears subjective and is likely to be closed. my answer: probably is subjective, but it is directly related to my issue i have with designing a database / writing my code, so i'd welcome any help. also i tried narrowing down the ideas to 2 so hopefully one of these will prevail, unless there already is an established solution for these kinds of things.

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  • C++ Switch won't compile with externally defined variable used as case

    - by C Nielsen
    I'm writing C++ using the MinGW GNU compiler and the problem occurs when I try to use an externally defined integer variable as a case in a switch statement. I get the following compiler error: "case label does not reduce to an integer constant". Because I've defined the integer variable as extern I believe that it should compile, does anyone know what the problem may be? Below is an example: test.cpp #include <iostream> #include "x_def.h" int main() { std::cout << "Main Entered" << std::endl; switch(0) { case test_int: std::cout << "Case X" << std::endl; break; default: std::cout << "Case Default" << std::endl; break; } return 0; } x_def.h extern const int test_int; x_def.cpp const int test_int = 0; This code will compile correctly on Visual C++ 2008. Furthermore a Montanan friend of mine checked the ISO C++ standard and it appears that any const-integer expression should work. Is this possibly a compiler bug or have I missed something obvious? Here's my compiler version information: Reading specs from C:/MinGW/bin/../lib/gcc/mingw32/3.4.5/specs Configured with: ../gcc-3.4.5-20060117-3/configure --with-gcc --with-gnu-ld --with-gnu-as --host=mingw32 --target=mingw32 --prefix=/mingw --enable-threads --disable-nls --enable-languages=c,c++,f77,ada,objc,java --disable-win32-registry --disable-shared --enable-sjlj-exceptions --enable-libgcj --disable-java-awt --without-x --enable-java-gc=boehm --disable-libgcj-debug --enable-interpreter --enable-hash-synchronization --enable-libstdcxx-debug Thread model: win32 gcc version 3.4.5 (mingw-vista special r3)

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  • Counting entries in a list of dictionaries: for loop vs. list comprehension with map(itemgetter)

    - by Dennis Williamson
    In a Python program I'm writing I've compared using a for loop and increment variables versus list comprehension with map(itemgetter) and len() when counting entries in dictionaries which are in a list. It takes the same time using a each method. Am I doing something wrong or is there a better approach? Here is a greatly simplified and shortened data structure: list = [ {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'biscuits and gravy'}, {'key1': False, 'dontcare': False, 'ignoreme': False, 'key2': True, 'filenotfound': 'peaches and cream'}, {'key1': True, 'dontcare': False, 'ignoreme': False, 'key2': False, 'filenotfound': 'Abbott and Costello'}, {'key1': False, 'dontcare': False, 'ignoreme': True, 'key2': False, 'filenotfound': 'over and under'}, {'key1': True, 'dontcare': True, 'ignoreme': False, 'key2': True, 'filenotfound': 'Scotch and... well... neat, thanks'} ] Here is the for loop version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True key1 = key2 = 0 for dictionary in list: if dictionary["key1"]: key1 += 1 if dictionary["key2"]: key2 += 1 print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above: Counts: key1: 3, subset key2: 2 Here is the other, perhaps more Pythonic, version: #!/usr/bin/env python # Python 2.6 # count the entries where key1 is True # keep a separate count for the subset that also have key2 True from operator import itemgetter KEY1 = 0 KEY2 = 1 getentries = itemgetter("key1", "key2") entries = map(getentries, list) key1 = len([x for x in entries if x[KEY1]]) key2 = len([x for x in entries if x[KEY1] and x[KEY2]]) print "Counts: key1: " + str(key1) + ", subset key2: " + str(key2) Output for the data above (same as before): Counts: key1: 3, subset key2: 2 I'm a tiny bit surprised these take the same amount of time. I wonder if there's something faster. I'm sure I'm overlooking something simple. One alternative I've considered is loading the data into a database and doing SQL queries, but the data doesn't need to persist and I'd have to profile the overhead of the data transfer, etc., and a database may not always be available. I have no control over the original form of the data. The code above is not going for style points.

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  • Best practice - logging events (general) and changes (database)

    - by b0x0rz
    need help with logging all activities on a site as well as database changes. requirements: * should be in database * should be easily searchable by initiator (user name / session id), event (activity type) and event parameters i can think of a database design but either it involves a lot of tables (one per event) so i can log each of the parameters of an event in a separate field OR it involves one table with generic fields (7 int numeric and 7 text types) and log everything in one table with event type field determining what parameter got written where (and hoping that i don't need more than 7 fields of a certain type, or 8 or 9 or whatever number i choose)... example of entries (the usual things): [username] login failed @datetime [username] login successful @datetime [username] changed password @datetime, estimated security of password [low/ok/high/perfect] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] clicked result [result number] [result id] after searching for [search string] and got [number of results] @datetime [username] changed profile name from [old name] to [new name] @datetime [username] verified name with [credit card type] credit card @datetime datbase table [table name] purged of old entries @datetime via automated process etc... so anyone dealt with this before? any best practices / links you can share? i've seen it done with the generic solution mentioned above, but somehow that goes against what i learned from database design, but as you can see the sheer number of events that need to be trackable (each user will be able to see this info) is giving me headaches, BUT i do LOVE the one event per table solution more than the generic one. any thoughts? edit: also, is there maybe an authoritative list of such (likely) events somewhere? thnx stack overflow says: the question you're asking appears subjective and is likely to be closed. my answer: probably is subjective, but it is directly related to my issue i have with designing a database / writing my code, so i'd welcome any help. also i tried narrowing down the ideas to 2 so hopefully one of these will prevail, unless there already is an established solution for these kinds of things.

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  • Extract domain from body of email

    - by iman453
    Hi, I was wondering if there is any way I could extract domain names from the body of email messages in python. I was thinking of using regular expressions, but I am not too great in writing them, and was wondering if someone could help me out. Here's a sample email body: <tr><td colspan="5"><font face="verdana" size="4" color="#999999"><b>Resource Links - </b></font><span class="snv"><a href="http://clk.about.com/?zi=4/RZ">Get Listed Here</a></span></td><td class="snv" valign="bottom" align="right"><a href="http://sprinks.about.com/faq/index.htm">What Is This?</a></td></tr><tr><td colspan="6" bgcolor="#999999"><img height="1" width="1"></td></tr><tr><td colspan="6"><map name="sgmap"><area href="http://x.about.com/sg/r/3412.htm?p=0&amp;ref=fooddrinksl_sg" shape="rect" coords="0, 0, 600, 20"><area href="http://x.about.com/sg/r/3412.htm?p=1&amp;ref=fooddrinksl_sg" shape="rect" coords="0, 55, 600, 75"><area href="http://x.about.com/sg/r/3412.htm?p=2&amp;ref=fooddrinksl_sg" shape="rect" coords="0, 110, 600, 130"></map><img border="0" src="http://z.about.com/sg/sg.gif?cuni=3412" usemap="#sgmap" width="600" height="160"></td></tr><tr><td colspan="6">&nbsp;</td></tr> <tr><td colspan="6"><a name="d"><font face="verdana" size="4" color="#cc0000"><b>Top Picks - </b></font></a><a href="http://slclk.about.com/?zi=1/BAO" class="srvb">Fun Gift Ideas</a><span class="snv"> from your <a href="http://chinesefood.about.com">Chinese Cuisine</a> Guide</span></td></tr><tr><td colspan="6" bgcolor="cc0000"><img height="1" width="1"></td></tr><tr><td colspan="6" class="snv"> So I would need "clk.about.com" etc. Thanks!

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  • Trying to create XPath from this HTML snippet

    - by doneright
    I have played for a while writing XPath but am unable to come up with exactly what I want. I'm trying to write XPath for link(click1 and click2 in code snippet below) based on known text(myidentity in code snippet below). Can someone take a look into and suggest possible solution? HTML code snippet: <div class="abc"> <a onclick="mycontroller.goto('xx','yy'); return false;" href="#"> <img src="images/controls/inheritance.gif"/> </a> myidentity <span> <a onclick="mycontroller.goto('xx','yy'); return false;" href="#">click1</a> <a onclick="mycontroller.goto('xx','yy'); return false;" href="#">click2</a> </span> </div>

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  • Why does resolveBinding() return null even though I setResolveBindings(true) on my ASTParser?

    - by Woody Zenfell III
    I am writing an Eclipse plug-in that uses JDT AST's ASTParser to parse a method. I am looking within that method for the creation of a particular type of object. When I find a ClassInstanceCreation, I call getType() on it to see what type is being instantiated. I want to be sure that the fully-resolved type being dealt with there is the one I think it is, so I tell the resultant Type object to resolveBinding(). I get null back even though there are no compilation errors and even though I called setResolveBindings(true) on my ASTParser. I gave my ASTParser (via setSource()) the ICompilationUnit that contains my method, so the parser has access to the entire workspace context. final IMethod method = ...; final ASTParser parser = ASTParser.newParser(AST.JLS3); parser.setResolveBindings(true); parser.setSource(method.getCompilationUnit()); parser.setSourceRange(method.getSourceRange().getOffset(), method.getSourceRange().getLength()); parser.setKind(ASTParser.K_CLASS_BODY_DECLARATIONS); final TypeDeclaration astRoot = (TypeDeclaration) parser.createAST(null); final ClassInstanceCreation classInstanceCreation = walkAstAndFindMyExpression(astRoot); final Type instantiatedType = classInstanceCreation.getType(); System.out.println("BINDING: " + instantiatedType.resolveBinding()); Why does resolveBinding() return null? How can I get the binding information?

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  • C# Fun with Generics - Mutual Dependencies

    - by Kenneth Cochran
    As an experiment I'm trying to write a generic MVP framework. I started with: public interface IPresenter<TView> where TView: IView<IPresenter<... { TView View { get; set;} } public interface IView<TPresenter> where TPresenter:IPresenter<IView<... { TPresenter Presenter { get; set; } } Obviously this can't work because the types of TView and TPresenter can't be resolved. You'd be writing Type<Type<... forever. So my next attempt looked like this: public interface IView<T> where T:IPresenter { ... } public interface IView:IView<IPresenter> { } public interface IPresenter<TView> where TView: IView { ... } public interface IPresenter: IPresenter<IView> { ... } This actually compiles and you can even inherit from these interfaces like so: public class MyView : IView, IView<MyPresenter> { ... } public class MyPresenter : IPresenter, IPresenter<MyView> { ... } The problem is in the class definition you have to define any members declared in the generic type twice. Not ideal but it still compiles. The problem's start creeping up when you actually try to access the members of a Presenter from a View or vice versa. You get an Ambiguous reference when you try to compile. Is there any way to avoid this double implementation of a member when you inherit from both interfaces? Is it even possible to resolve two mutually dependent generic types at compile time?

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  • How to view shell commands used by eclipse "run configurations"

    - by gmale
    Given a "run configuration" in Eclipse, I want to print out the associated shell command that would be used to run it. For example: Right now, in Eclipse, if I click "play" it will run: mvn assembly:directory -Dmaven.test.skip=true I don't see that command, I just know that's what the IDE must run, at some point. However, some of the other run configurations are far more complex with long classpaths and virtual machine options and, frankly, sometimes I have no idea what the equivalent shell command would be (particularly when it comes to Flex). There must be some way to access the shell command that would be associated with a "Run Configuration" in Eclipse/Flex Builder. This information must be available, which leads me to believe someone has written a plugin to display it. Or maybe there's already an option built into Eclipse for accessing this. So is there a way to, essentially, convert an Eclipse run configuration into a shell command? (for context only: I'm asking because I'm writing a bash script that automates everything I do, during development--from populating the Database all the way to opening Firefox and clearing the cache before running the web app. So every command I run from the IDE needs to exist in the script. Some are tricky to figure out.)

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  • In App Purchase Unique Identifying Data

    - by dageshi
    O.K so I'm writing a iPhone travel guide, you purchase a subscription to a travel guide for 3 months, it downloads a fairly hefty database and for 3 months that database gets updated weekly with new stuff. Now what I'd like to do is make the user enter their email address as a one off action before they purchase their first guide, for China say. The purpose for doing this is 1) To allow me to contact the user by email when they add a note/tip for a particular place (the app will allow them to send notes & information to me) 2) To Uniquely identify who has purchased the subscription so that if they wipe their device and reinstall the app they can plug the email address in and pickup their subscriptions again. Or so they can use the same subscription on another device they own. My concerns are 1) Will Apple allow the email method of restoring functionality to a second or restored device? 2) As long as I tell the user what I'm using their email address for (aka I won't sell it to anyone else and use it for X purposes) will it be o.k to ask for said email address? And as a side note, can I tack the devices unique id onto my server comms to track devices or is apple going to through a hissy fit about that as well?

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  • delete vs execSQL commands android

    - by erik
    so i have a databas, SQLiteDatabase db I am writing a couple private methods in my manager class that will be called by a public method: public void updateData (MakeabilityModel newData){ SQLiteDatabase db = this.getWritableDatabase(); db.beginTransaction(); try { reWriteSVTable(db, list); db.setTransactionSuccessful(); } catch (Exception e){ //TODO through rollback message? e.printStackTrace(); } finally { db.endTransaction(); } } //Private Methods private void clearTable(SQLiteDatabase db, String table){ db.delete(table, null, null); } private void reWriteSVTable(SQLiteDatabase db, List<MakeabilityLens> lenses){ clearTable(db, singleVision); ContentValues cv; for(int i=0; i<lenses.size(); i++){ cv = new ContentValues(); cv.put(colScreenID, hsID); cv.put(colIconID, id); cv.put(colRank, hsTotal); db.insert(isLookUp, colID, cv); } } My question is this.. i want to be able to throw sql exceptions back to the public method so that if there is an exception, it will kill the transaction and rollback ALL data.. it appears that using delete() and insert() methods are cleaner than execSQL() but don't throw sqlExceptions. execSQL() on the other hand does? do i need to uses execSQL and how do i insure that hsould it throws an exception in any of the private methods that it will catch it and roll it back in the private method

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  • Parsing data with Clojure, interval problem.

    - by Andrea Di Persio
    Hello! I'm writing a little parser in clojure for learning purpose. basically is a TSV file parser that need to be put in a database, but I added a complication. The complication itself is that in the same file there are more intervals. The file look like this: ###andreadipersio 2010-03-19 16:10:00### USER COMM PID PPID %CPU %MEM TIME root launchd 1 0 0.0 0.0 2:46.97 root DirectoryService 11 1 0.0 0.2 0:34.59 root notifyd 12 1 0.0 0.0 0:20.83 root diskarbitrationd 13 1 0.0 0.0 0:02.84` .... ###andreadipersio 2010-03-19 16:20:00### USER COMM PID PPID %CPU %MEM TIME root launchd 1 0 0.0 0.0 2:46.97 root DirectoryService 11 1 0.0 0.2 0:34.59 root notifyd 12 1 0.0 0.0 0:20.83 root diskarbitrationd 13 1 0.0 0.0 0:02.84 I ended up with this code: (defn is-header? "Return true if a line is header" [line] (> (count (re-find #"^\#{3}" line)) 0)) (defn extract-fields "Return regex matches" [line pattern] (rest (re-find pattern line))) (defn process-lines [lines] (map process-line lines)) (defn process-line [line] (if (is-header? line) (extract-fields line header-pattern)) (extract-fields line data-pattern)) My idea is that in 'process-line' interval need to be merged with data so I have something like this: ('andreadipersio', '2010-03-19', '16:10:00', 'root', 'launchd', 1, 0, 0.0, 0.0, '2:46.97') for every row till the next interval, but I can't figure how to make this happen. I tried with something like this: (def process-line [line] (if is-header? line) (def header-data (extract-fields line header-pattern))) (cons header-data (extract-fields line data-pattern))) But this doesn't work as excepted. Any hints? Thanks!

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  • Fastest inline-assembly spinlock

    - by sigvardsen
    I'm writing a multithreaded application in c++, where performance is critical. I need to use a lot of locking while copying small structures between threads, for this I have chosen to use spinlocks. I have done some research and speed testing on this and I found that most implementations are roughly equally fast: Microsofts CRITICAL_SECTION, with SpinCount set to 1000, scores about 140 time units Implementing this algorithm with Microsofts InterlockedCompareExchange scores about 95 time units Ive also tried to use some inline assembly with __asm {} using something like this code and it scores about 70 time units, but I am not sure that a proper memory barrier has been created. Edit: The times given here are the time it takes for 2 threads to lock and unlock the spinlock 1,000,000 times. I know this isn't a lot of difference but as a spinlock is a heavily used object, one would think that programmers would have agreed on the fastest possible way to make a spinlock. Googling it leads to many different approaches however. I would think this aforementioned method would be the fastest if implemented using inline assembly and using the instruction CMPXCHG8B instead of comparing 32bit registers. Furthermore memory barriers must be taken into account, this could be done by LOCK CMPXHG8B (I think?), which guarantees "exclusive rights" to the shared memory between cores. At last [some suggests] that for busy waits should be accompanied by NOP:REP that would enable Hyper-threading processors to switch to another thread, but I am not sure whether this is true or not? From my performance-test of different spinlocks, it is seen that there is not much difference, but for purely academic purpose I would like to know which one is fastest. However as I have extremely limited experience in the assembly-language and with memory barriers, I would be happy if someone could write the assembly code for the last example I provided with LOCK CMPXCHG8B and proper memory barriers in the following template: __asm { spin_lock: ;locking code. spin_unlock: ;unlocking code. }

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  • Encrypt a file base upon a pregenerated "key" C#

    - by Anubis
    Hello everyone. I'm trying to determine the best course of action to implement a simple "licensing" system with a partner of mine. The concept is: Generate an encrypted value based upon several internal hardware components. Have the customer send this value to us which we will implement into our key generator. Once we have that, we add any other restrictions on the license (user, expires, etc.). From there we generate a file which we send to the customer they can add to their installation and voila, happy people about. I have the first part all done. My next part is trying to figure out which encryption methodology I would need to use. I already know Symmetric Encryption is pretty much the only route I can take. Most of the information I have found involves .NET already creating a key from its own internal methods. That's a bit of background, my question is: "Which encryption method could I use which would allow me to encrypt the restrictions based upon the "id" I was given from the customer's computer?" I'm writing this in C# by the way. Any ideas would be greatly appreciated! Take Care!

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  • How should we setup up complex situations for tests?

    - by ShaneC
    I'm currently working on what I would call integration tests. I want to verify that if a WCF service is called it will do what I expect. Let's take a very simple scenario. Assume we have a contract object that we can put on hold or take off hold. Now writing the put on hold test is quite simple. You create a contract instance and execute the code that puts it on code. The question I have comes when we want to test the taking off hold service call. The problem is that putting a contract on hold can be actually quite complicated leading to various objects all be modified. So usually I would use the Builder pattern and do something like this.. var onHoldContract = new ContractBuilder().PutOnHold().Build(); The problem I have with this is now I have to pretty much replicate a large part of my put on hold service. Now when I change what putting something on hold means I have two places I have to modify. The other option that immediately jumps out at me is to just use the put on hold service as part of my test setup but now I'm coupling my test to the success of another piece of code which is something I don't like to do since it can lead to failures in one spot breaking unrelated tests elsewhere (if put on hold failed for example). Any other options I'm missing out here? or opinions on which method is preferable and why?

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  • Changing <object> height and width works in Chrome but not Firefox or IE. Why?

    - by Michael Hopkins
    I am making a site with two Youtube videos. These videos use the raw embed code from Youtube. The site's design doesn't work with any of the default Youtube sizes, so I am writing code to automatically resize the video. Here is my code. There will never be more than these two tags on the page, otherwise I'd do a better job selecting the videos. <script language='JavaScript' type='text/javascript'> var x=document.getElementsByTagName('object'); x.[0].width='350'; x.[0].height='350'; x.[1].width='350'; x.[1].height='350'; </script> For reference, here's a sample default Youtube embed that the code might alter: <object width="480" height="385"> <param name="movie" value="http://www.youtube-nocookie.com/v/zSgiXGELjbc&hl=en_US&fs=1&rel=0"></param> <param name="allowFullScreen" value="true"></param> <param name="allowscriptaccess" value="always"></param> <embed src="http://www.youtube-nocookie.com/v/zSgiXGELjbc&hl=en_US&fs=1&rel=0" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed> </object> In Chrome, the video players sit perfectly in a 350x350 box. In IE and FF (latest versions), the videos are the unchanged, normal size. I cannot find anything in Google that explans why this won't work. I have tried using setattribute, for loops, adjusting both and , single-quotes and double-quotes, etc. Any ideas what is going wrong?

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  • How to: Simulating keystroke inputs in shell to an app running in an embedded target

    - by fzkl
    I am writing an automation script that runs on an embedded linux target. A part of the script involves running an app on the target and obtaining some data from the stdout. Stdout here is the ssh terminal connection I have to the target. However, this data is available on the stdout only if certain keys are pressed and the key press has to be done on the keyboard connected to the embedded target and not on the host system from which I have ssh'd into the target. Is there any way to simulate this? Edit: Elaborating on what I need - I have an OpenGL app that I run on the embedded linux (works like regular linux) target. This displays some graphics on the embedded system's display device. Pressing f on the keyboard connected to the target outputs the fps data onto the ssh terminal from which I control the target. Since I am automating the process of running this OpenGL app and obtaining the fps scores, I can't expect a keyboard to be connected to the target let alone expect a user to input a keystroke on the embedded target keyboard. How do I go about this? Thanks.

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  • GNU Make - Dependencies on non program code

    - by Tim Post
    A requirement for a program I am writing is that it must be able to trust a configuration file. To accomplish this, I am using several kinds of hashing algorithms to generate a hash of the file at compile time, this produces a header with the hashes as constants. Dependencies for this are pretty straight forward, my program depends on config_hash.h, which has a target that produces it. The makefile looks something like this : config_hash.h: $(SH) genhash config/config_file.cfg > $(srcdir)/config_hash.h $(PROGRAM): config_hash.h $(PROGRAM_DEPS) $(CC) ... ... ... I'm using the -M option to gcc, which is great for dealing with dependencies. If my header changes, my program is rebuilt. My problem is, I need to be able to tell if the config file has changed, so that config_hash.h is re-generated. I'm not quite sure how explain that kind of dependency to GNU make. I've tried listing config/config_file.cfg as a dependency for config_hash.h, and providing a .PHONY target for config_file.cfg without success. Obviously, I can't rely on the -M switch to gcc to help me here, since the config file is not a part of any object code. Any suggestions? Unfortunately, I can't post much of the Makefile, or I would have just posted the whole thing.

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  • PHP Socket Server vs node.js: Web Chat

    - by Eliasdx
    I want to program a HTTP WebChat using long-held HTTP requests (Comet), ajax and websockets (depending on the browser used). Userdatabase is in mysql. Chat is written in PHP except maybe the chat stream itself which could also be written in javascript (node.js): I don't want to start a php process per user as there is no good way to send the chat messages between these php childs. So I thought about writing an own socket server in either PHP or node.js which should be able to handle more then 1000 connections (chat users). As a purely web developer (php) I'm not much familiar with sockets as I usually let web server care about connections. The chat messages won't be saved on disk nor in mysql but in RAM as an array or object for best speed. As far as I know there is no way to handle multiple connections at the same time in a single php process (socket server), however you can accept a great amount of socket connections and process them successive in a loop (read and write; incoming message - write to all socket connections). The problem is that there will most-likely be a lag with ~1000 users and mysql operations could slow the whole thing down which will then affect all users. My question is: Can node.js handle a socket server with better performance? Node.js is event-based but I'm not sure if it can process multiple events at the same time (wouldn't that need multi-threading?) or if there is just an event queue. With an event queue it would be just like php: process user after user. I could also spawn a php process per chat room (much less users) but afaik there are singlethreaded IRC servers which are also capable to handle thousands of users. (written in c++ or whatever) so maybe it's also possible in php. I would prefer PHP over Node.js because then the project would be php-only and not a mixture of programming languages. However if Node can process connections simultaneously I'd probably choose it.

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