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  • Need events to execute on timer events, metronome precision.

    - by user295734
    I setup a timer to call an event in my application. The problme is the event execution is being skewed by other windows operations. Ex. openning and window, loading a webpage. I need the event to excute exactly on time, every time. When i first set up the app, used a sound file, like a metronome to listen to the even firing, in a steady state, its firing right on, but as soon do something in the windows environment, the sound fires slower, then sort of sppeds up a bit to catch up. So i added a logging method to the event to ctahc the timer ticks. From that data, it appears that the timer is not being affected by the windows app, but my application event calls are being affected. I figured this out by checking the datetime.now in the event, and if i set it to 250 milliseconds, which is 4 clicks per second. You get data something like below. (sec):(ms) 1:000 1:250 1:500 1:750 2:000 2:250 2:500 2:750 3:000 3:250 3:500 3:750 (lets say i execute some windows event)(time will skew) 4:122 4:388 4:600 4:876 (stop doing what i was doing in windows) (going to shorten the data for simplicit, my list was 30sec long) 5:124 5:268 5:500 5:750 (you would se the time go back the same milliseconds it was at the begining) 6:000 6:250 6:500 6:750 7:000 7:250 7:500 7:750 So i'm thinking the timer continues to fire on the same millisecond every time, but its the event that is being skewed to fire off time by other windows operations. Its not a huge skew, but for what i need to accomplish, its unacceptable. Is there anyhting i can do in .NET, hoping to use XAML/WPF application, thats will correct the skewing of events? thx.

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  • Function returning dictionary, not seen by calling function

    - by twiga
    Hi There, I have an interesting problem, which is a function that returns a Dictionary<String,HashSet<String>>. The function converts some primitive structs to a Dictionary Class. The function is called as follows: Dictionary<String, HashSet<String>> Myset = new Dictionary<String,HashSet<String>>(); Myset = CacheConverter.MakeDictionary(_myList); Upon execution of the two lines above, Myset is non-existent to the debugger. Adding a watch results in: "The name 'Myset' does not exist in the current context" public Dictionary<String, HashSet<String>> MakeDictionary(LightWeightFetchListCollection _FetchList) { Dictionary<String, HashSet<String>> _temp = new Dictionary<String, HashSet<String>>(); // populate the Dictionary // return return _temp; } The Dictionary _temp is correctly populated by the called function and _temp contains all the expected values. The problem seems to be with the dictionary not being returned at all. Examples I could find on the web of functions returning primitive Dictionary<string,string> work as expected.

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  • Apache CXF REST Services w/ Spring AOP

    - by jconlin
    I'm trying to get Apache CXF JAX-RS services working with Spring AOP. I've created a simple logging class: public class AOPLogger{ public void logBefore(){ System.out.println("Logging Before!"); } } My Spring configuration (beans.xml): <aop:config> <aop:aspect id="aopLogger" ref="test.aop.AOPLogger"> <aop:before method="logBefore" pointcut="execution(* test.rest.RestService(..))"/> </aop:aspect> </aop:config> <bean id="aopLogger" class="test.aop.AOPLogger"/> I always get an NPE in RestService when a call is made to a Method getServletRequest(), which has: return messageContext.getHttpServletRequest(); If I remove the aop configuration or comment it out from my beans.xml, everything works fine. All of my actual Rest services extend test.rest.RestService (which is a class) and call getServletRequest(). I'm just trying to just get AOP up and running based off of the example in the CXF JAX-RS documentation. Does anyone have any idea what I'm doing wrong? Thanks!

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  • Maven Mojo & SCM Plugin: Check for a valid working directory

    - by Patrick Bergner
    Hi there. I'm using maven-scm-plugin from within a Mojo and am trying to figure out how to determine if a directory D is a valid working directory of an SCM URL U (i.e. a checkout of U to D already happened). The context is that I want to do a checkout of U if D is a working set or do an update if it isn't. The plan is to check out U to D if D does not exist, update D if D is a valid working directory of U, display an error if D exists and is not a valid working directory of U. What I tried is to call ScmManager.status(), ScmManager.list() and ScmManager.changelog() and try to guess something from their results. But that didn't work. The results from status and changelog always return something positive (isSuccess() = true, getChangedFiles() = valid List, no exceptions to catch), whereas list throws an exception in any case. ScmRepository and ScmFileSet don't seem to provide suitable methods as well. An option would be to always do an update if D exists but then I cannot tell if it is a working directory of U or any SCM working directory at all. The ideal solution would be independent of the actual SCM system and a specific ScmVersion. Thanks for your help! Patrick

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  • DBD::CSV: Problem with file-name-extensions

    - by sid_com
    In this script I have problems with file-name-extensions: if I use /home/mm/test_x it works, with file named /home/mm/test_x.csv it doesn't: #!/usr/bin/env perl use warnings; use strict; use 5.012; use DBI; my $table_1 = '/home/mm/test_1.csv'; my $table_2 = '/home/mm/test_2.csv'; #$table_1 = '/home/mm/test_1'; #$table_2 = '/home/mm/test_2'; my $dbh = DBI->connect( "DBI:CSV:" ); $dbh->{RaiseError} = 1; $table_1 = $dbh->quote_identifier( $table_1 ); $table_2 = $dbh->quote_identifier( $table_2 ); my $sth = $dbh->prepare( "SELECT a.id, a.name, b.city FROM $table_1 AS a NATURAL JOIN $table_2 AS b" ); $sth->execute; $sth->dump_results; $dbh->disconnect; Output with file-name-extention: DBD::CSV::st execute failed: Execution ERROR: No such column '"/home/mm/test_1.csv".id' called from /usr/local/lib/perl5/site_perl/5.12.0/x86_64-linux/DBD/File.pm at 570. Output without file-name-extension: '1', 'Brown', 'Laramie' '2', 'Smith', 'Watertown' 2 rows Is this a bug?

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  • MYSQL fetch 10 posts, each w/ vote count, sorted by vote count, limited by where clause on posts

    - by nibblebot
    I want to fetch a set of Posts w/ vote count listed, sorted by vote count (e.g.) Post 1 - Post Body blah blah - Votes: 500 Post 2 - Post Body blah blah - Votes: 400 Post 3 - Post Body blah blah - Votes: 300 Post 4 - Post Body blah blah - Votes: 200 I have 2 tables: Posts - columns - id, body, is_hidden Votes - columns - id, post_id, vote_type_id Here is the query I've tried: SELECT p.*, v.yes_count FROM posts p LEFT JOIN (SELECT post_id, vote_type_id, COUNT(1) AS yes_count FROM votes WHERE (vote_type_id = 1) GROUP BY post_id ORDER BY yes_count DESC LIMIT 0, 10) v ON v.post_id = p.id WHERE (p.is_hidden = 0) ORDER BY yes_count DESC LIMIT 0, 10 Correctness: The above query almost works. The subselect is including votes for posts that have is_hidden = 1, so when I left join it to posts, if a hidden post is in the top 10 (ranked by votes), I can end up with records with NULL on the yes_count field. Performance: I have ~50k posts and ~500k votes. On my dev machine, the above query is running in .4sec. I'd like to stay at or below this execution time. Indexes: I have an index on the Votes table that covers the fields: vote_type_id and post_id EXPLAIN id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY p ALL NULL NULL NULL NULL 45985 Using where; Using temporary; Using filesort 1 PRIMARY <derived2> ALL NULL NULL NULL NULL 10 2 DERIVED votes ref VotingPost VotingPost 4 319881 Using where; Using index; Using temporary; Using filesort

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  • Set up Gitosis, but can't clone

    - by Tim Rupe
    I've set up Gitosis on a remote Ubuntu box which I will refer to as linuxserver as my host in the following commands. I'm also connecting from a Windows box using Cygwin. I followed the instructions according to: http://scie.nti.st/2007/11/14/hosting-git-repositories-the-easy-and-secure-way I had no problems up until I needed to clone the gitosis-admin repository to my local machine git clone git@linuxserver:gitosis-admin.git When I do this, the command executes, but hangs there displaying nothing until I ctrl-c to get back to a command prompt. No messages are displayed at all. I'm pretty sure I have my ssh keys set up properly, because logging in using "ssh linuxserver" into my regular account works perfectly without asking for a password. Edit: Over the weekend I set up a near identical Ubuntu box at home, and had no problem setting up Gitosis. The only difference was that I was connecting from OSX instead of Cygwin. Edit: I've also discovered that when using the Bash Shell provided with "Git Extensions", I have no problems, so the issue definitely seems to be some kind of Cygwin conflict. Edit: Just an update, but about a month after posting this question, I switched to Mercurial, and found that I prefer it much more than git. Thanks for the suggestions, but I don't plan on going back to git to try any of them out.

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  • Conditional macro expansion

    - by Dave DeLong
    Heads up: This is a weird question. I've got some really useful macros that I like to use to simplify some logging. For example I can do Log(@"My message with arguments: %@, %@, %@", @"arg1", @"arg2", @"arg3"), and that will get expanded into a more complex method invocation that includes things like self, _cmd, __FILE__, __LINE__, etc, so that I can easily track where things are getting logged. This works great. Now I'd like to expand my macros to not only work with Objective-C methods, but general C functions. The problem is the self and _cmd portions that are in the macro expansion. These two parameters don't exist in C functions. Ideally, I'd like to be able to use this same set of macros within C functions, but I'm running into problems. When I use (for example) my Log() macro, I get compiler warnings about self and _cmd being undeclared (which makes total sense). My first thought was to do something like the following (in my macro): if (thisFunctionIsACFunction) { DoLogging(nil, nil, format, ##__VA_ARGS__); } else { DoLogging(self, _cmd, format, ##__VA_ARGS__); } This still produces compiler warnings, since the entire if() statement is substituted in place of the macro, resulting in errors with the self and _cmd keywords (even though they will never be executed during function execution). My next thought was to do something like this (in my macro): if (thisFunctionIsACFunction) { #define SELF nil #define CMD nil } else { #define SELF self #define CMD _cmd } DoLogging(SELF, CMD, format, ##__VA_ARGS__); That doesn't work, unfortunately. I get "error: '#' is not followed by a macro parameter" on my first #define. My other thought was to create a second set of macros, specifically for use in C functions. This reeks of a bad code smell, and I really don't want to do this. Is there some way I can use the same set of macros from within both Objective-C methods and C functions, and only reference self and _cmd if the macro is in an Objective-C method?

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  • Can a large transaction log cause cpu hikes to occur

    - by Simon Rigby
    Hello all, I have a client with a very large database on Sql Server 2005. The total space allocated to the db is 15Gb with roughly 5Gb to the db and 10 Gb to the transaction log. Just recently a web application that is connecting to that db is timing out. I have traced the actions on the web page and examined the queries that execute whilst these web operation are performed. There is nothing untoward in the execution plan. The query itself used multiple joins but completes very quickly. However, the db server's CPU hikes to 100% for a few seconds. The issue occurs when several simultaneous users are working on the system (when I say multiple .. read about 5). Under this timeouts start to occur. I suppose my question is, can a large transaction log cause issues with CPU performance? There is about 12Gb of free space on the disk currently. The configuration is a little out of my hands but the db and log are both on the same physical disk. I appreciate that the log file is massive and needs attending to, but I'm just looking for a heads up as to whether this may cause CPU spikes (ie trying to find the correlation). The timeouts are a recent thing and this app has been responsive for a few years (ie its a recent manifestation). Many Thanks,

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  • TypeError: Error #1009 - (Null reference error) With Flash.

    - by Wind Chimez
    I am not an expert in flash, but i do work with AS and tweak Flash projects , though not having deep expertise in it. Currently i need to revamp a flash website done by one another guy, and the code base given to me, upon execution is throwing the following error. "--- TypeError: Error #1009: Cannot access a property or method of a null object reference. at NewSite_fla::MainTimeline/__setProp_ContactOutP1_ContactOut_Contents_0() at NewSite_fla::MainTimeline/frame1() --" The structure of the project is like, it has the different sections split into different movie clips. There is no single main timeline, but click actions on different areas of seperate movie clips will take them between one another. All the AS logic of event handling are written inline in FLA , no seperate Document class exists. Preloader Movie clip is the first one getting loaded. As i understood the error is getting thrown initially itself, and it is not happening due to any Action script logic written inline, because it is throwing error even before hitting the first inline AS code. I am not able to figure Out what exactly it causing the problem, or where to resolve it. I really got stuck at this point. Any help will be great.I had not seen the particular solution i am looking for anywhere yet, though Error #1009 is common. I uploaded the fla, here ( http://tinyurl.com/249e95p ), for reference.It may not be working , since the included/refered video files and all are not there, but reviwing the action code/movie clips will be possible. Please let me know if somebody will be able to trace the issue exactly.

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  • Flex 3: should I provide prepared data to my component or make it to process data before display?

    - by grapkulec
    I'm starting to learn a little Flex just for fun and maybe to prove that I still can learn something new :) I have some idea for a project and one of its parts is a tree component which could display data in different ways depending on configuration. The idea There is list of objects having properties like id, date, time, name, description. And sometimes list should be displayed like this: first level: date second level: time third level: name and sometimes like this: first level: year second level: month third level: day fourth level: time and name By level I mean level of nesting of course. So, we can have years, that have months, that have days, that have hours and so forth. The problem What could be the best way to do it? I mean, should I prepare data for different ways of nesting outside of component or even outside of flex? I can do it at web service level in C# where I plan to have database access layer and send to flex nice and ready to display XML or array of objects. But I wonder if that won't cause additional and maybe unneccessary network traffic. I tried to hack some code in my component to convert my data objects into XML or ArrayCollection but I don't know enough of Flex and got stuck on elimination of duplicates or getting specific data by some key value. Usually to do such things I have STL with maps, sets and vectors and I find Flex arrays and even Dictionary a little bit confusing (I've read language reference and googled without any significant luck). The question So, to sum things up: should I give my tree component data prepared just for chosen type of display or should I try to do it internally inside component (or some helper class written in ActionScript)?

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  • How to call Twiter's Streaming/Filter Feed with urllib2/httplib?

    - by Simon
    Update: I switched this back from answered as I tried the solution posed in cogent Nick's answer and switched to Google's urlfetch: logging.debug("starting urlfetch for http://%s%s" % (self.host, self.url)) result = urlfetch.fetch("http://%s%s" % (self.host, self.url), payload=self.body, method="POST", headers=self.headers, allow_truncated=True, deadline=5) logging.debug("finished urlfetch") but unfortunately finished urlfetch is never printed - I see the timeout happen in the logs (it returns 200 after 5 seconds), but execution doesn't seem tor return. Hi All- I'm attempting to play around with Twitter's Streaming (aka firehose) API with Google App Engine (I'm aware this probably isn't a great long term play as you can't keep the connection perpetually open with GAE), but so far I haven't had any luck getting my program to actually parse the results returned by Twitter. Some code: logging.debug("firing up urllib2") req = urllib2.Request(url="http://%s%s" % (self.host, self.url), data=self.body, headers=self.headers) logging.debug("called urlopen for %s %s, about to call urlopen" % (self.host, self.url)) fobj = urllib2.urlopen(req) logging.debug("called urlopen") When this executes, unfortunately, my debug output never shows the called urlopen line printed. I suspect what's happening is that Twitter keeps the connection open and urllib2 doesn't return because the server doesn't terminate the connection. Wireshark shows the request being sent properly and a response returned with results. I tried adding Connection: close to my request header, but that didn't yield a successful result. Any ideas on how to get this to work? thanks -Simon

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  • Need help in tuning a sql-query

    - by Viper
    Hello, i need some help to boost this SQL-Statement. The execution time is around 125ms. During the runtime of my program this sql (better: equally structured sqls for different tables) will be called 300.000 times. The average row count in the tables lies around 10.000.000 rows and new rows (updates/inserts) will be added with a timestamp each day. Data which are interesting for this particular export-program lies in the last 1-3 days. Maybe this is helpful for an index to create. The data i need is the current valid row for a given id and the forerunner datarow to get the updates (if exists). We use a Oracle 11g database and Dot.Net Framework 3.5 SQL-Statement to boost: select ID_SOMETHING, -- Number(12) ID_CONTRIBUTOR, -- Char(4 Byte) DATE_VALID_FROM, -- DATE DATE_VALID_TO -- DATE from TBL_SOMETHING XID where ID_SOMETHING = :ID_INSTRUMENT and ID_CONTRIBUTOR = :ID_CONTRIBUTOR and DATE_VALID_FROM <= :EXPORT_DATE and DATE_VALID_TO >= :EXPORT_DATE order by DATE_VALID_FROM asc; Here i uploaded the current Explain-Plan for this query. I'm not a database expert so i don't know which index-type would fit best for this requirement. I have seen that there are many different possible index-types which could be applied. Maybe Oracle Optimizer Hints are helpful, too. Does anyone has a good idea for tuning this sql or can point me in a right direction?

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  • Use Lambda in Attribute constructor to get method's parameters

    - by Anthony Shaw
    I'm not even sure if this is possible, but I've exhausted all of my ideas trying to figure this out, so I figured I'd send this out to the community and see what you thought. And, if it's not possible, maybe you'd have some ideas as well. I'm trying to make an Attribute class that I can add to a method that would allow me to use a lambda expression to get each parameter of the method public ExampleAttribute : Attribute { public object Value { get; set; } public ExampleAttribute(--something here to make the lambda work--, object value) { Value = value; } } I'd like to be able to something like this below: [Example(x=x.Id, 4)] [Example(x=x.filter, "string value")] public ActionResult Index(int Id, string filter) { return View(); } I understand that I might be completely dreaming with this idea. I'm basically trying to write a model to allow for self-documenting REST API Documentation. In a recent project here at work we wrote a dozen or so services with 5 to 15 methods on each, I figure it's easier to write something to do this, than to hand code a documentation page for each. I would plan to eventually release this as an open-source project once I have it in a place that I feel it's releasable.

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  • Best intro to C++ static metaprogramming?

    - by jwfearn
    Static metaprogramming (aka "template metaprogramming") is a great C++ technique that allows the execution of programs at compile-time. A light bulb went off in my head as soon as I read this canonical metaprogramming example: #include <iostream> using namespace std; template< int n > struct factorial { enum { ret = factorial< n - 1 >::ret * n }; }; template<> struct factorial< 0 > { enum { ret = 1 }; }; int main() { cout << "7! = " << factorial< 7 >::ret << endl; // 5040 return 0; } If one wants to learn more about C++ static metaprogramming, what are the best sources (books, websites, on-line courseware, whatever)?

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  • Unable to change the system zone setting on Windows Server 2008 R2.

    - by Ganesh
    Hi All, I have an MFC application that tries to change the system zone setting on the Windows Server 2008 R2. I am using the SetTimeZoneInformation() API which fails with the error code 1314 .i.e. “A required privilege is not held by the client.”. Please refer the sample code below: TIME_ZONE_INFORMATION l_TimeZoneInfo; DWORD l_dwRetVal = 0; ZeroMemory(&l_TimeZoneInfo, sizeof(TIME_ZONE_INFORMATION)); l_TimeZoneInfo.Bias = -330; l_TimeZoneInfo.StandardBias = 0; l_TimeZoneInfo.StandardDate.wDay = 0; l_TimeZoneInfo.StandardDate.wDayOfWeek = 0; l_TimeZoneInfo.StandardDate.wHour = 0; l_TimeZoneInfo.StandardDate.wMilliseconds = 0; l_TimeZoneInfo.StandardDate.wMinute = 0; l_TimeZoneInfo.StandardDate.wMonth = 0; l_TimeZoneInfo.StandardDate.wSecond = 0; l_TimeZoneInfo.StandardDate.wYear = 0; CString l_csDaylightName = _T("India Daylight Time"); CString l_csStdName = _T("India Standard Time"); wcscpy(l_TimeZoneInfo.DaylightName,l_csDaylightName.GetBuffer(l_csDaylightName.GetLength())); wcscpy(l_TimeZoneInfo.StandardName,l_csStdName.GetBuffer(l_csStdName.GetLength())); ::SetLastError(0); if(0 == ::SetTimeZoneInformation(&l_TimeZoneInfo)) { l_dwRetVal = ::GetLastError(); CString l_csErr = _T(""); l_csErr.Format(_T("%d"),l_dwRetVal); } The MFC application has been developed using Visual Studio 2008 and is UAC aware i.e. the application has UAC enabled in its manifest file with the UAC execution level set to “HighestAvailable”. I have administrator privileges and when I run the application it still fails to change the system zone setting. Thanks in Advance, Ganesh

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  • Code bacteria: evolving mathematical behavior

    - by Stefano Borini
    It would not be my intention to put a link on my blog, but I don't have any other method to clarify what I really mean. The article is quite long, and it's in three parts (1,2,3), but if you are curious, it's worth the reading. A long time ago (5 years, at least) I programmed a python program which generated "mathematical bacteria". These bacteria are python objects with a simple opcode-based genetic code. You can feed them with a number and they return a number, according to the execution of their code. I generate their genetic codes at random, and apply an environmental selection to those objects producing a result similar to a predefined expected value. Then I let them duplicate, introduce mutations, and evolve them. The result is quite interesting, as their genetic code basically learns how to solve simple equations, even for values different for the training dataset. Now, this thing is just a toy. I had time to waste and I wanted to satisfy my curiosity. however, I assume that something, in terms of research, has been made... I am reinventing the wheel here, I hope. Are you aware of more serious attempts at creating in-silico bacteria like the one I programmed? Please note that this is not really "genetic algorithms". Genetic algorithms is when you use evolution/selection to improve a vector of parameters against a given scoring function. This is kind of different. I optimize the code, not the parameters, against a given scoring function.

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  • Partial Evaluation of ConstantExpression in ExpressionTreeVisitor

    - by Andrew Theken
    Hi all, I am not an Expression Tree master by any stretch of the imagination, what I have is code that looks like this: int external = 10; using(var session = new Session()) { session.Add(new Product { Name = "test1", Price = 20 }); session.Add(new Product {Name = "test", Price = 10}); var product = session.Products.Where(p => p.Price == external).FirstOrDefault(); Assert.Equal(10, product.Price); } Session implements all the IQueryProvider, IQueryable interfaces you'd come to expect from a LINQ Provider. When I execute the query, everything goes to plan until I read the ConstantExpression for "external", at which point, I am at a loss as to how to move forward because: //constant is ConstantExpression for "external" on the right side of the "p.Price == external" expression above. var t = constant.GetType(); //evaluates to class called "<>c__DisplayClass2" - with a member named "external" that has the value 10. The question is basically.. How can I just access the value of the member "external" - is there a way to accomplish this without using reflection? or am I cooked? What am I missing?

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  • Getting identity from Ado.Net Update command

    - by rboarman
    My scenario is simple. I am trying to persist a DataSet and have the identity column filled in so I can add child records. Here's what I've got so far: using (SqlConnection connection = new SqlConnection(connStr)) { SqlDataAdapter adapter = new SqlDataAdapter("select * from assets where 0 = 1", connection); adapter.MissingMappingAction = MissingMappingAction.Passthrough; adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey; SqlCommandBuilder cb = new SqlCommandBuilder(adapter); var insertCmd = cb.GetInsertCommand(true); insertCmd.Connection = connection; connection.Open(); adapter.InsertCommand = insertCmd; adapter.InsertCommand.CommandText += "; set ? = SCOPE_IDENTITY()"; adapter.InsertCommand.UpdatedRowSource = UpdateRowSource.OutputParameters; var param = new SqlParameter("RowId", SqlDbType.Int); param.SourceColumn = "RowId"; param.Direction = ParameterDirection.Output; adapter.InsertCommand.Parameters.Add(param); SqlTransaction transaction = connection.BeginTransaction(); insertCmd.Transaction = transaction; try { assetsImported = adapter.Update(dataSet.Tables["Assets"]); transaction.Commit(); } catch (Exception ex) { transaction.Rollback(); // Log an error } connection.Close(); } The first thing that I noticed, besides the fact that the identity value is not making its way back into the DataSet, is that my change to add the scope_identity select statement to the insert command is not being executed. Looking at the query using Profiler, I do not see my addition to the insert command. Questions: 1) Why is my addition to the insert command not making its way to the sql being executed on the database? 2) Is there a simpler way to have my DataSet refreshed with the identity values of the inserted rows? 3) Should I use the OnRowUpdated callback to add my child records? My plan was to loop through the rows after the Update() call and add children as needed. Thank you in advance. Rick

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  • Are short tags *that* bad?

    - by Col. Shrapnel
    Everyone here on SO says it's bad, for 3 main reasons: XML is used everywhere You can't control where your script is going to be run short tags are going to be removed in PHP6 But let's see closer at them: Last one is easy - it's just not true. XML is not really a problem. If you want to use short tags, it won't be a problem for you to write a single tag using PHP echo, <?="<?XML...?>"?>. Anyway, why not to leave such a trifle thing for one's own judgment? PHP configuration access. Oh yes, the only thing that can be really considered as a reason. Of course in case you plan to spread your code wide. But if you don't? I think most of scripts being written not for the wide spread, but just for one place. If you can use short tags in that place - why to abandon them? Anyway, it's the only template we are talking about. If you don't like short tags, PHP native template is probably not for you, why not to try Smarty then? Well, the question is: is there any other real reasons to abandon short tags and make it strict recommendation? Or, as it was said, better to leave short tags alone?

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  • How to distinguish between two different UDP clients on the same IP address?

    - by Ricket
    I'm writing a UDP server, which is a first for me; I've only done a bit of TCP communications. And I'm having trouble figuring out exactly how to distinguish which user is which, since UDP deals only with packets rather than connections and I therefore cannot tell exactly who I'm communicating with. Here is pseudocode of my current server loop: DatagramPacket p; socket.receive(p); // now p contains the user's IP and port, and the data int key = getKey(p); if(key == 0) { // connection request key = makeKey(p); clients.add(key, p.ip); send(p.ip, p.port, key); // give the user his key } else { // user has a key // verify key belongs to that IP address // lookup the user's session data based on the key // react to the packet in the context of the session } When designing this, I kept in mind these points: Multiple users may exist on the same IP address, due to the presence of routers, therefore users must have a separate identification key. Packets can be spoofed, so the key should be checked against its original IP address and ignored if a different IP tries to use the key. The outbound port on the client side might change among packets. Is that third assumption correct, or can I simply assume that one user = one IP+port combination? Is this commonly done, or should I continue to create a special key like I am currently doing? I'm not completely clear on how TCP negotiates a connection so if you think I should model it off of TCP then please link me to a good tutorial or something on TCP's SYN/SYNACK/ACK mess. Also note, I do have a provision to resend a key, if an IP sends a 0 and that IP already has a pending key; I omitted it to keep the snippet simple. I understand that UDP is not guaranteed to arrive, and I plan to add reliability to the main packet handling code later as well.

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  • .Net Finalizer Order / Semantics in Esent and Ravendb

    - by mattcodes
    Help me understand. I've read that "The time and order of execution of finalizers cannot be predicted or pre-determined" Correct? However looking at RavenDB source code TransactionStorage.cs I see this ~TransactionalStorage() { try { Trace.WriteLine( "Disposing esent resources from finalizer! You should call TransactionalStorage.Dispose() instead!"); Api.JetTerm2(instance, TermGrbit.Abrupt); } catch (Exception exception) { try { Trace.WriteLine("Failed to dispose esent instance from finalizer because: " + exception); } catch { } } } The API class (which belongs to Managed Esent) which presumable takes handles on native resources presumably using a SafeHandle? So if I understand correctly the native handles SafeHandle can be finalized before TransactionStorage which could have undesired effects, perhaps why Ayende has added an catch all clause around this? Actually diving into Esent code, it does not use SafeHandles. According to CLR via C# this is dangerous? internal static class SomeType { [DllImport("Kernel32", CharSet=CharSet.Unicode, EntryPoint="CreateEvent")] // This prototype is not robust private static extern IntPtr CreateEventBad( IntPtr pSecurityAttributes, Boolean manualReset, Boolean initialState, String name); // This prototype is robust [DllImport("Kernel32", CharSet=CharSet.Unicode, EntryPoint="CreateEvent")] private static extern SafeWaitHandle CreateEventGood( IntPtr pSecurityAttributes, Boolean manualReset, Boolean initialState, String name) public static void SomeMethod() { IntPtr handle = CreateEventBad(IntPtr.Zero, false, false, null); SafeWaitHandle swh = CreateEventGood(IntPtr.Zero, false, false, null); } } Managed Esent (NativeMEthods.cs) looks like this (using Ints vs IntPtrs?): [DllImport(EsentDll, CharSet = EsentCharSet, ExactSpelling = true)] public static extern int JetCreateDatabase(IntPtr sesid, string szFilename, string szConnect, out uint dbid, uint grbit); Is Managed Esent handling finalization/dispoal the correct way, and second is RavenDB handling finalizer the corret way or compensating for Managed Esent?

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  • DataTable won't DataBind with a DataTable.NewRow()

    - by David
    Is DataRow.NewRow() insufficient as the only row in a DataTable? I would expect this to work, but it doesn't. It's near the end of my Page_Load inside my If(!Postback) block. gridCPCP is GridView DataTable dt = new DataTable(); dt.Columns.Add("ID", int.MinValue.GetType()); dt.Columns.Add("Code", string.Empty.GetType()); dt.Columns.Add("Date", DateTime.MinValue.GetType()); dt.Columns.Add("Date2", DateTime.MinValue.GetType()); dt.Columns.Add("Filename", string.Empty.GetType()); //code to add rows if (dt.Rows.Count > 0) { gridCPCP.DataSource = dt; gridCPCP.DataBind(); } else { dt.Rows.Add(dt.NewRow()); gridCPCP.DataSource = dt; gridCPCP.DataBind(); //EXCEPTION int TotalColumns = gridCPCP.Rows[0].Cells.Count; gridCPCP.Rows[0].Cells.Clear(); gridCPCP.Rows[0].Cells.Add(new TableCell()); gridCPCP.Rows[0].Cells[0].ColumnSpan = TotalColumns; gridCPCP.Rows[0].Cells[0].Text = "No Record Found"; } The exception throws on gridCPCP.DataBind() and only when execution reaches the else block. If there were rows added above via dt.Rows.Add(new object[] { ... } binding works. System.ArgumentOutOfRangeException: Length cannot be less than zero. Parameter name: length

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  • Cache consistency & spawning a thread

    - by Dave Keck
    Background I've been reading through various books and articles to learn about processor caches, cache consistency, and memory barriers in the context of concurrent execution. So far though, I have been unable to determine whether a common coding practice of mine is safe in the strictest sense. Assumptions The following pseudo-code is executed on a two-processor machine: int sharedVar = 0; myThread() { print(sharedVar); } main() { sharedVar = 1; spawnThread(myThread); sleep(-1); } main() executes on processor 1 (P1), while myThread() executes on P2. Initially, sharedVar exists in the caches of both P1 and P2 with the initial value of 0 (due to some "warm-up code" that isn't shown above.) Question Strictly speaking – preferably without assuming any particular CPU – is myThread() guaranteed to print 1? With my newfound knowledge of processor caches, it seems entirely possible that at the time of the print() statement, P2 may not have received the invalidation request for sharedVar caused by P1's assignment in main(). Therefore, it seems possible that myThread() could print 0. References These are the related articles and books I've been reading. (It wouldn't allow me to format these as links because I'm a new user - sorry.) Shared Memory Consistency Models: A Tutorial hpl.hp.com/techreports/Compaq-DEC/WRL-95-7.pdf Memory Barriers: a Hardware View for Software Hackers rdrop.com/users/paulmck/scalability/paper/whymb.2009.04.05a.pdf Linux Kernel Memory Barriers kernel.org/doc/Documentation/memory-barriers.txt Computer Architecture: A Quantitative Approach amazon.com/Computer-Architecture-Quantitative-Approach-4th/dp/0123704901/ref=dp_ob_title_bk

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  • Images in database vs file system

    - by Jesse
    We have a project coming up where we will be building a whole backend CMS system that will power our entire extranet and intranet with one package. The question I have been trying to find an answer to is which is better: storing images in the database (SQL Server 2005) so we may have integrity, single replication plan, etc OR storing on the file system? One issue we have is that we have multiple servers load balanced that require to have the same data at all times. As of now we have SQL replication taking care of that but file replication seems to be a little tougher. Another concern we have is that we would like to have multiple resolutions of the same image, we are not sure if creating and storing each version on the file system would be best or maybe dynamically pulling and creating the resolution image we would like upon request. Our concerns are the with the following: Data integrity Data replication Multiple resolutions Speed of database vs file system Overhead load of database vs file system Data management and backup Does anyone have a similar situation or have any input on what would be recommended? Thanks in advance for the help!

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