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  • Trying to use linq to search based on table with hierarchical data.

    - by Steph
    Duplicate many times over (and also these) I have a table called Types that has the following columns. ID Level Name ParentID (The ID of the parent row) and a table called ParentObject which has the following columns. ID TypeID there are 4 different level (possibly to be expanded to more). So if I had ID: 1 Level: 0 Name: Level0 ParentID: null ID: 2 Level: 1 Name: Level1 ParentID: 1 ID: 3 Level: 2 Name: Level2 ParentID: 2 ID: 4 Level: 3 Name: Level3 ParentID: 3 ID: 5 Level: 4 Name: Level4 ParentID: 4 In the ParentObject table I store the tree by just storing the lowest level ID. So if the ID i have is 4, I know that the tree actually goes Level0 - Level1 - Level2 - Level3 Basically, I need to be able to search all objects for a certain Type, or Type Level 2 for example in a linq statement. Say that the TypeID stored in the ParentObject table is 4, so Level3. But I actually want to search for all ParentObjects where the Level 2 type has an ID of 3. What would be the best way to do this since the id stored could be a level1 or a level2, etc.? Preferably in one linq statement if possible.

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  • Symfony/Propel NestedSet left/right ID corruption/adjustment

    - by Mike Crowe
    Hi folks, I have a nested set application that seems to be getting corrupted. Here's what I'm seeing: We're using nested sets for a binary tree (any node can have 2 children). It appears to be working fine, but some event causes a discrepancy. For instance, when I do a getNumberOfDescendants() for the root node, it will slowly increase as this event happens. However, displaying the tree works fine, as does inserting (apparently). Has anybody seen anything like this before? For instance, my repair program shows this as the repairs that it makes: User pxxxxx left 0=>0, right 145=>129 User axxxxx left 1=>1, right 124=>106 User mxxxxx left 119=>117, right 120=>118 User fxxxxx left 125=>107, right 144=>128 User fxxxxx left 126=>108, right 131=>113 User rxxxxx left 127=>109, right 128=>110 User mxxxxx left 129=>111, right 130=>112 User mxxxxx left 132=>114, right 143=>127 User cxxxxx left 133=>115, right 142=>126 User gxxxxx left 134=>116, right 137=>121 User mxxxxx left 135=>119, right 136=>120 User jxxxxx left 138=>122, right 141=>125 User axxxxx left 139=>123, right 140=>124 I thought at first it was when I deleted a user, but it has since occurred w/o that event. Anybody know of a cause that might generate this? I've tested ad nauseum on my local machine, but I can't duplicate it. I do have an issue where my production box is PHP 5.2.0, whereas my test device is 5.2.10. Could that be an issue? TIA Mike

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  • Keyword to SQL search

    - by jdelator
    Use Case When a user goes to my website, they will be confronted with a search box much like SO. They can search for results using plan text. ".net questions", "closed questions", ".net and java", etc.. The search will function a bit different that SO, in that it will try to as much as possible of the schema of the database rather than a straight fulltext search. So ".net questions" will only search for .net questions as opposed to .net answers (probably not applicable to SO case, just an example here), "closed questions" will return questions that are closed, ".net and java" questions will return questions that relate to .net and java and nothing else. Problem I'm not too familiar with the words but I basically want to do a keyword to SQL driven search. I know the schema of the database and I also can datamine the database. I want to know any current approaches there that existing out already before I try to implement this. I guess this question is for what is a good design for the stated problem. Proposed My proposed solution so far looks something like this Clean the input. Just remove any special characters Parse the input into chunks of data. Break an input of "c# java" into c# and java Also handle the special cases like "'c# java' questions" into 'c# java' and "questions". Build a tree out of the input Bind the data into metadata. So convert stuff like closed questions and relate it to the isclosed column of a table. Convert the tree into a sql query. Thoughts/suggestions/links?

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  • Can't get MySQL source query to work using Python mysqldb module

    - by Chris
    I have the following lines of code: sql = "source C:\\My Dropbox\\workspace\\projects\\hosted_inv\\create_site_db.sql" cursor.execute (sql) When I execute my program, I get the following error: Error 1064: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'source C:\My Dropbox\workspace\projects\hosted_inv\create_site_db.sql' at line 1 Now I can copy and past the following into mysql as a query: source C:\\My Dropbox\\workspace\\projects\\hosted_inv\\create_site_db.sql And it works perfect. When I check the query log for the query executed by my script, it shows that my query was the following: source C:\\My Dropbox\\workspace\\projects\\hosted_inv\\create_site_db.sql However, when I manually paste it in and execute, the entire create_site_db.sql gets expanded in the query log and it shows all the sql queries in that file. Am I missing something here on how mysqldb does queries? Am I running into a limitation. My goal is to run a sql script to create the schema structure, but I don't want to have to call mysql in a shell process to source the sql file. Any thoughts? Thanks!

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  • Caching a column in a polymorphic relationship

    - by Brendon Muir
    I have content management system application that uses a polymorphic tree table as the core of its arrangement. I've come into a problem where once the tree grows quite large, and because we have quite a few different modules (about 25), just doing :include = :instance doesn't cut the mustard. Instance is the name of our polymorphic relationship. The funny part is that in most cases when I want a large list of these items, all I really want is their name from the associated table (for the purposes of an index bar for example), all the rest is in the central table. So I thought that I should probably implement some sort of column cache for the name in the central table. (Like a counter cache that rails already does). I was just wondering if a plugin exists to manage this already? If not, I was just going to add a 'name' column to the central table and because all the polymorphic models inherit off a superclass, just add a callback that pushes the name across to the central table whenever the item is created or updated. I'd then just do a big migration to populate it in the first place? Any flaws to that design? I suppose to be more flexible the column could be some kind of serialised cache where I could store other things later on if need be? Gah! :D

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  • How to launch multiple Internet Explorer windows/tabs from batch file?

    - by TheZenker
    I would like a batch file to launch two separate programs then have the command line window close. Actually, to clarify, I am launching Internet Explorer with two different URLs. So far I have something like this: start "~\iexplore.exe" "url1" start "~\iexplore.exe" "url2" What I get is one instance of Internet Explorer with only the second URL loaded. Seems the second is replacing the second. I seem to remember a syntax where I would load a new command line window and pass the command to execute on load, but can't find the reference. As a second part of the question: what is a good reference URL to keep for the times you need to write a quick batch file? Edit: I have marked an answer, because it does work. I now have two windows open, one for each URL. (thanks!) The funny thing is that without the /d approach using my original syntax I get different results based on whether I have a pre-existing Internet Explorer instance open. If I do I get two new tabs added for my two URLs (sweet!) If not I get only one final tab for the second URL I passed in.

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  • Webservice returning 403 error

    - by user48408
    I'm wondering whether I'm receiving the 403 errors because there are too many attempted connections being made to the webservice. If this is the case how do I get around it? I've tried creating a new instance of InternalWebService each time and disposing of the old one but I get the same problem. I've disabled the firewall and the webservice is located locally at the moment. I beginning to think it may be a problem with the credentials but the control tree is populated via the webservice at some stage. If I browse to the webmethods in my browser I can run them all. I return an instance of the webservice from my login handler loginsession.cs: static LoginSession() { ... g_NavigatorWebService = new InternalWebService(); g_NavigatorWebService.Credentials = System.Net.CredentialCache.DefaultCredentials; ... } public static InternalWebService NavigatorWebService { get { return g_NavigatorWebService; } } I have a tree view control which uses the webservice to populate itself. IncidentTreeViewControl.cs: public IncidentTreeView() { InitializeComponent(); m_WebService = LoginSession.NavigatorWebService; ... } public void Populate() { m_WebService.BeginGetIncidentSummaryByCompany(new AsyncCallback(IncidentSummaryByClientComplete), null); m_WebService.BeginGetIncidentSummaryByDepartment(new AsyncCallback(IncidentSummaryByDepartmentComplete), null); ... } private void IncidentSummaryByClientComplete(IAsyncResult ar) { MyTypedDataSet data = m_WebService.EndGetIncidentSummaryByCompany(ar); //403 ..cont... } I'm getting the 403 on the last line.

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  • Graph navigation problem

    - by affan
    I have graph of components and relation between them. User open graph and want to navigate through the graph base on his choice. He start with root node and click expand button which reveal new component that is related to current component. The problem is with when use decide to collapse a node. I have to choose a sub-tree to hide and at same time leave graph in consistent state so that there is no expanded node with missing relation to another node in graph. Now in case of cyclic/loop between component i have difficult of choosing sub-tree. For simplicity i choose the order in which they were expanded. So if a A expand into B and C collapse A will hide the nodes and edge that it has created. Now consider flowing scenario. [-] mean expanded state and [+] mean not yet expanded. A is expanded to reveal B and C. And then B is expanded to reveal D. C is expanded which create a link between C and exiting node D and also create node E. Now user decide to collapse B. Since by order of expansion D is child of B it will collapse and hide D. This leave graph in inconsistent state as C is expanded with edge to D but D is not anymore there if i remove CD edge it will still be inconsistent. If i collapse C. And E is again a cyclic link e.g to B will produce the same problem. /-----B[-]-----\ A[-] D[+] \-----C[-]-----/ \ E[+] So guys any idea how can i solve this problem. User need to navigate through graph and should be able to collapse but i am stuck with problem of cyclic nodes in which case any of node in loop if collapse will leave graph in inconsistent state.

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  • Problem calling std::max

    - by Eric
    I compiled my bison-generated files in Visual Studio and got these errors: ...\position.hh(83): error C2589: '(' : illegal token on right side of '::' ...\position.hh(83): error C2059: syntax error : '::' ...\position.hh(83): error C2589: '(' : illegal token on right side of '::' ...\position.hh(83): error C2059: syntax error : '::' The corresponding code is: inline void columns (int count = 1) { column = std::max (1u, column + count); } I think the problem is with std::max; if I change std::max to equivalent code then there is no problem anymore, but is there a better solution instead of changing the generated code? Here is the bison file I wrote: // // bison.yy // %skeleton "lalr1.cc" %require "2.4.2" %defines %define parser_class_name "cmd_parser" %locations %debug %error-verbose %code requires { class ParserDriver; } %parse-param { ParserDriver& driver } %lex-param { ParserDriver& driver } %union { struct ast *a; double d; struct symbol *s; struct symlist *sl; int fn; } %code { #include "helper_func.h" #include "ParserDriver.h" std::string error_msg = ""; } %token <d> NUMBER %token <s> NAME %token <fn> FUNC %token EOL %token IF THEN ELSE WHILE DO LET %token SYM_TABLE_OVERFLOW %token UNKNOWN_CHARACTER %nonassoc <fn> CMP %right '=' %left '+' '-' %left '*' '/' %nonassoc '|' UMINUS %type <a> exp stmt list explist %type <sl> symlist %{ extern int yylex(yy::cmd_parser::semantic_type *yylval, yy::cmd_parser::location_type* yylloc); %} %start calclist %% ... grammar rules ...

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  • SQL Stored Queries - use result of query as boolean based on existence of records

    - by Christian Mann
    Just getting into SQL stored queries right now... anyway, here's my database schema (simplified for YOUR convenience): member ------ id INT PK board ------ id INT PK officer ------ id INT PK If you're into OOP, Officer Inherits Board Inherits Member. In other words, if someone is listed on the officer table, s/he is listed on the board table and the member table. I want to find out the highest privilege level someone has. So far my SP looks like this: DELIMITER // CREATE PROCEDURE GetAuthLevel(IN targetID MEDIUMINT) BEGIN IF SELECT `id` FROM `member` WHERE `id` = targetID; THEN IF SELECT `id` FROM `board` WHERE `id` = targetID; THEN IF SELECT `id` FROM `officer` WHERE `id` = targetID; THEN RETURN 3; /*officer*/ ELSE RETURN 2; /*board member*/ ELSE RETURN 1; /*general member*/ ELSE RETURN 0; /*not a member*/ END // DELIMITER ; The exact text of the error is #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT id FROM member WHERE id = targetID; THEN IF SEL' at line 4 I suspect the issue is in the arguments for the IF blocks. What I want to do is return true if the result-set is at least one -- i.e. the id was found in the table. Do any of you guys see anything to do here, or should I reconsider my database design into this:? person ------ id INT PK level SMALLINT

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  • perl dynamic path given to 'use lib'

    - by Ed Hyer
    So, my code (Perl scripts and Perl modules) sits in a tree like this: trunk/ util/ process/ scripts/ The 'util' directory has, well, utilities, that things in the 'process/' dir need. They get access like this: use FindBin; use lib "$FindBin::Bin/../util"; use UtilityModule qw(all); That construct doesn't care where you start, as long as you're at the same level in the tree as "util/". But I decided that 'scripts/' was getting too crowded, so I created scripts/scripts1 scripts/scripts2 Now I see that this doesn't work. If I run a script 'trunk/scripts/scripts1/call_script.pl', and it calls '/trunk/process/process_script.pl', then 'process_script.pl' will fail trying to get the routines from UtilityModule(), because the path that FindBin returns is the path of the top-level calling script. The first ten ways I thought of to solve this all involved something like: use lib $path_that_came_from_elsewhere; but that seems to be something Perl doesn't like to do, except via that FindBin trick. I tried some things involving BEGIN{} blocks, but i don't really know what I'm doing there, and will likely just end up refactoring. But if someone has some clever insight into this type of problem, this would be a good chance to earn some points!

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  • haskell: a data structure for storing ascending integers with a very fast lookup

    - by valya
    Hello! (This question is related to my previous question, or rather to my answer to it.) I want to store all qubes of natural numbers in a structure and look up specific integers to see if they are perfect cubes. For example, cubes = map (\x -> x*x*x) [1..] is_cube n = n == (head $ dropWhile (<n) cubes) It is much faster than calculating the cube root, but It has complexity of O(n^(1/3)) (am I right?). I think, using a more complex data structure would be better. For example, in C I could store a length of an already generated array (not list - for faster indexing) and do a binary search. It would be O(log n) with lower ?oefficient than in another answer to that question. The problem is, I can't express it in Haskell (and I don't think I should). Or I can use a hash function (like mod). But I think it would be much more memory consuming to have several lists (or a list of lists), and it won't lower the complexity of lookup (still O(n^(1/3))), only a coefficient. I thought about a kind of a tree, but without any clever ideas (sadly I've never studied CS). I think, the fact that all integers are ascending will make my tree ill-balanced for lookups. And I'm pretty sure this fact about ascending integers can be a great advantage for lookups, but I don't know how to use it properly (see my first solution which I can't express in Haskell).

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  • showing null rows using join

    - by Pradyut Bhattacharya
    Hi, In mysql i m selecting from a table shouts having a foreign key to another table named "roleuser" with the matching column as user_id Now the user_id column in the shouts table for some rows is null (not actually null but with no inserts in mysql) How to show all the rows of the shouts table either with user_id null or not I m executing the sql statement SELECT s.*, r.firstname, r.lastname FROM shouts s left join roleuser r where r.user_id = s.user_id limit 50; which does not executes and shows You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'where r.user_id = s.user_id limit 50' at line 2 but using inner join the sql executes which shows rows which only have user_id values in the shouts table. the nulls are not shown. SELECT s.*, r.firstname, r.lastname FROM shouts s inner join roleuser r where r.user_id = s.user_id limit 50; How can i show all the rows from the shouts table and null values in the firstname and lastname columns where the user_id is null in the shouts table. If not at all possible with sql may be using stored procedures... Thanks Pradyut

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  • forward/strong enum in VS2010

    - by Noah Roberts
    At http://blogs.msdn.com/vcblog/archive/2010/04/06/c-0x-core-language-features-in-vc10-the-table.aspx there is a table showing C++0x features that are implemented in 2010 RC. Among them are listed forwarding enums and strongly typed enums but they are listed as "partial". The main text of the article says that this means they are either incomplete or implemented in some non-standard way. So I've got VS2010RC and am playing around with the C++0x features. I can't figure these ones out and can't find any documentation on these two features. Not even the simplest attempts compile. enum class E { test }; int main() {} fails with: 1e:\dev_workspace\experimental\2010_feature_assessment\2010_feature_assessment\main.cpp(518): error C2332: 'enum' : missing tag name 1e:\dev_workspace\experimental\2010_feature_assessment\2010_feature_assessment\main.cpp(518): error C2236: unexpected 'class' 'E'. Did you forget a ';'? 1e:\dev_workspace\experimental\2010_feature_assessment\2010_feature_assessment\main.cpp(518): error C3381: 'E' : assembly access specifiers are only available in code compiled with a /clr option 1e:\dev_workspace\experimental\2010_feature_assessment\2010_feature_assessment\main.cpp(518): error C2143: syntax error : missing ';' before '}' 1e:\dev_workspace\experimental\2010_feature_assessment\2010_feature_assessment\main.cpp(518): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== int main() { enum E : short; } Fails with: 1e:\dev_workspace\experimental\2010_feature_assessment\2010_feature_assessment\main.cpp(513): warning C4480: nonstandard extension used: specifying underlying type for enum 'main::E' 1e:\dev_workspace\experimental\2010_feature_assessment\2010_feature_assessment\main.cpp(513): error C2059: syntax error : ';' ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ========== So it seems it must be some totally non-standard implementation that has allowed them to justify calling this feature "partially" done. How would I rewrite that code to access the forwarding and strong type feature?

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  • Why I am not able to update the column based on a condition which is not the primary key

    - by Gaurav Sharma
    Why I am not able to update the column based on a condition which is not the primary key. I am trying to update the constituencies table where name matches a specific criterial as shown below but the below queries shows an error Error code 1064, SQL state 42000: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'table constituencies set city_id = '1' where constituencies.name = "East Delhi"' at line 1 update table constituencies set city_id = '1' where constituencies.name = "East Delhi"; update table constituencies set city_id = '1' where constituencies.name = "South Delhi"; update table constituencies set city_id = '1' where constituencies.name = "Delhi Sadar"; update table constituencies set city_id = '1' where constituencies.name = "Karol Bagh"; update table constituencies set city_id = '1' where constituencies.name = "New Delhi"; update table constituencies set city_id = '1' where constituencies.name = "Outer Delhi"; update table constituencies set city_id = '1' where constituencies.name = "North East Delhi"; update table constituencies set city_id = '1' where constituencies.name = "North West Delhi"; update table constituencies set city_id = '1' where constituencies.name = "West Delhi"; Is it necessary that the condition should be checked with a primary key only ? Please throw some light on the above.

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  • Where to put external archives to configure running in Eclipse?

    - by Buggieboy
    As a Java/Eclipse noob coming from a Visual Studio .NET background, I'm trying to understand how to set up my run/debug environment in the Eclipse IDE so I can start stepping through code. I have built my application with separate src and bin hierarchies for each library project, and each project has its own jar. For example, in a Windows environment, I have something like: c:\myapp\myapp_main\src\com\mycorp\myapp\main ...and a parallel "bin" tree like this: c:\myapp\myapp_main\bin\com\mycorp\myapp\main Other supporting projects are, similarly: **c:\myapp\myapp_util\src\com\mycorp\myapp\uti**l (and a parallel "bin" tree.) ... etc. So, I end up with, e.g., myapp_util.jar in the ...\myapp_util\bin... path and then add that as an external archive to my myapp_main project. I also use utilities like gluegen-rt.jar, which I add ad external dependencies to the projects requiring them. I have been able to run outside of the Eclipse environment, by copying all my project jars, gluegen-rt DLL, etc., into a "lib" subfolder of some directory and executing something like: java -Djava.library.path=lib -DfullScreen=false -cp lib/gluegen-rt.jar;lib/myapp_main.jar;lib/myapp_util.jar; com.mycorp.myapp.Main When I first pressed F11 to debug, however, I got a message about something like /com/sun/../glugen... not being found by the class loader. So, to debug, or even just run, in Ecplipse, I tried setting up my VM arguments in the Galileo Debug - (Run/Debug) Configurations to be the command line above, beginning at "-Djava.libary.path...". I've put a lib subdirectory - just like the above with all jars and the native gluegen DLL - in various places, such as beneath the folder that my main jar is built in and as a subfolder of my Ecplipse starting workspace folder, but now Eclipse can't find the main class: java.lang.NoClassDefFoundError: com.mycorp.myapp.Main Although the Classpath says that it is using the "default classpath", whatever that is. Bottom line, how do I assemble the constituent files of a multi-project application so that I can run or debug in Ecplipse?

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  • Error in asp.net c# code (mysql database connection)

    - by Ishan
    My code is to update a record if it already exists in database else insert as a new record. My code is as follows: protected void Button3_Click(object sender, EventArgs e) { OdbcConnection MyConnection = new OdbcConnection("Driver={MySQL ODBC 3.51 Driver};Server=localhost;Database=testcase;User=root;Password=root;Option=3;"); MyConnection.Open(); String MyString = "select fil_no,orderdate from temp_save where fil_no=? and orderdate=?"; OdbcCommand MyCmd = new OdbcCommand(MyString, MyConnection); MyCmd.Parameters.AddWithValue("", HiddenField4.Value); MyCmd.Parameters.AddWithValue("", TextBox3.Text); using (OdbcDataReader MyReader4 = MyCmd.ExecuteReader()) { //** if (MyReader4.Read()) { String MyString1 = "UPDATE temp_save SET order=? where fil_no=? AND orderdate=?"; OdbcCommand MyCmd1 = new OdbcCommand(MyString1, MyConnection); MyCmd1.Parameters.AddWithValue("", Editor1.Content.ToString()); MyCmd1.Parameters.AddWithValue("", HiddenField1.Value); MyCmd1.Parameters.AddWithValue("", TextBox3.Text); MyCmd1.ExecuteNonQuery(); } else { // set the SQL string String strSQL = "INSERT INTO temp_save (fil_no,order,orderdate) " + "VALUES (?,?,?)"; // Create the Command and set its properties OdbcCommand objCmd = new OdbcCommand(strSQL, MyConnection); objCmd.Parameters.AddWithValue("", HiddenField4.Value); objCmd.Parameters.AddWithValue("", Editor1.Content.ToString()); objCmd.Parameters.AddWithValue("", TextBox3.Text); // execute the command objCmd.ExecuteNonQuery(); } } } I am getting the error as: ERROR [42000] [MySQL][ODBC 3.51 Driver][mysqld-5.1.51-community]You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'order,orderdate) VALUES ('04050040272009','&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&' at line 1 The datatype for fields in table temp_save are: fil_no-->INT(15)( to store a 15 digit number) order-->LONGTEXT(to store contents from HTMLEditor(ajax control)) orderdate-->DATE(to store date) Please help me to resolve my error.

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  • Lightweight spinlocks built from GCC atomic operations?

    - by Thomas
    I'd like to minimize synchronization and write lock-free code when possible in a project of mine. When absolutely necessary I'd love to substitute light-weight spinlocks built from atomic operations for pthread and win32 mutex locks. My understanding is that these are system calls underneath and could cause a context switch (which may be unnecessary for very quick critical sections where simply spinning a few times would be preferable). The atomic operations I'm referring to are well documented here: http://gcc.gnu.org/onlinedocs/gcc-4.4.1/gcc/Atomic-Builtins.html Here is an example to illustrate what I'm talking about. Imagine a RB-tree with multiple readers and writers possible. RBTree::exists() is read-only and thread safe, RBTree::insert() would require exclusive access by a single writer (and no readers) to be safe. Some code: class IntSetTest { private: unsigned short lock; RBTree<int>* myset; public: // ... void add_number(int n) { // Aquire once locked==false (atomic) while (__sync_bool_compare_and_swap(&lock, 0, 0xffff) == false); // Perform a thread-unsafe operation on the set myset->insert(n); // Unlock (atomic) __sync_bool_compare_and_swap(&lock, 0xffff, 0); } bool check_number(int n) { // Increment once the lock is below 0xffff u16 savedlock = lock; while (savedlock == 0xffff || __sync_bool_compare_and_swap(&lock, savedlock, savedlock+1) == false) savedlock = lock; // Perform read-only operation bool exists = tree->exists(n); // Decrement savedlock = lock; while (__sync_bool_compare_and_swap(&lock, savedlock, savedlock-1) == false) savedlock = lock; return exists; } }; (lets assume it need not be exception-safe) Is this code indeed thread-safe? Are there any pros/cons to this idea? Any advice? Is the use of spinlocks like this a bad idea if the threads are not truly concurrent? Thanks in advance. ;)

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  • How to force an HTML JLabel in a JTree to resize when the font changes

    - by Mike
    I'm updating a Java Swing application to support the user switching the app's font from normal size to a larger size (so the user can switch between the two sizes at runtime). One problem I'm having is with a JTree that uses HTML for the tree nodes to underline the text in some nodes (the HTML is just embedded in the JLabel of each tree node). One extra thing to know about the nodes is that they're a custom component, adding a JCheckBox in front of each JLabel. The problem is that once the JTree is visible, increasing the font size causes the nodes (containing underlined text) to not resize. The HTML for those nodes seems to prevent the node from becoming wider, so when the font changes, the text becomes truncated. I think my options are to either: 1) use another approach to make the text underlined, since removing the HTML from the JLabel causes it to resize properly when the font size changes, or 2) keep the HTML formatting and somehow force the JTree/JLabels to resize when the font size is updated (possibly by firing a property change event?). The code already calls SwingUtilities.updateComponentTreeUI() on the parent JFrame when the font size gets updated. Any help would be greatly appreciated. Thanks in advance! -Mike

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  • What is the best way to attach static methods to classes rather than to instances of a class?

    - by John Gietzen
    If I have a method for calculating the greatest common divisor of two integers as: public static int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); } What would be the best way to attach that to the System.Math class? Here are the three ways I have come up with: public static int GCD(this int a, int b) { return b == 0 ? a : b.GCD(a % b); } // Lame... var gcd = a.GCD(b); and: public static class RationalMath { public static int GCD(int a, int b) { return b == 0 ? a : GCD(b, a % b); } } // Lame... var gcd = RationalMath.GCD(a, b); and: public static int GCD(this Type math, int a, int b) { return b == 0 ? a : typeof(Math).GCD(b, a % b); } // Neat? var gcd = typeof(Math).GCD(a, b); The desired syntax is Math.GCD since that is the standard for all mathematical functions. Any suggestions? What should I do to get the desired syntax?

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  • Ruby on Rails: How to sanitize a string for SQL when not using find and other built-in methods?

    - by williamjones
    I'm trying to sanitize a string that involves user input without having to resort to manually crafting my own possibly buggy regex if possible. There are a number of methods in Rails that can allow you to enter in native SQL commands, how do people escape user input for those? The question I'm asking is a broad one, but in my particular case, I'm working with a column in my Postgres database that Rails does not natively understand as far as I know, the tsvector, which holds plain text search information. Rails is able to write and read from it as if it's a string, however, unlike a string, it doesn't seem to be automatically escaping it when I do things like vector= inside the model. For example, when I do model.name='::', where name is a string, it works fine. When I do model.vector='::' it errors out: ActiveRecord::StatementInvalid: PGError: ERROR: syntax error in tsvector: "::" "vectors" = E'::' WHERE "id" = 1 This seems to be a problem caused by lack of escaping of the semicolons, and I can manually set the vector='\:\:' fine. I also had the bright idea, maybe I can just call something like: ActiveRecord::Base.connection.execute "UPDATE medias SET vectors = ? WHERE id = 1", "::" However, this syntax doesn't work, because the raw SQL commands don't have access to find's method of escaping and inputting strings by using the ? mark. This strikes me as the same problem as calling connection.execute with any type of user input, as it all boils down to sanitizing the strings, but I can't seem to find any way to manually call Rails' SQL string sanitization methods. Can anyone provide any advice?

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  • Silverlight 4 seems like starving of memory

    - by Marco
    I have been playing a bit with Silverlight and try to port my Silverlight 3.0 application to Silverlight 4.0. My application loads different XAP files and upon a user request create an instance of a Xaml user control and adds it to the main container, in a sort of MEF approach in order I can have an extensible and pluggable application. The application is pretty huge and to keep acceptable the performances and the initial loading I have built up some helper classes to load in the background all pages and user controls that might be used later on. On Silverlight 3.0 everything was running smoothly without any problem so far. Switching to SL 4.0 I have noticed that when the process approaches to create the instances of the user controls the layout freezes unexpectedly for a minute and sometimes for more. Looking at the task manager the memory usage of IE jumps from 50MB to 400MB and sometimes up to 1.5 GB. If the process won't take that much the layout is rendered properly even though the memory usage is still extremely high. Otherwise everything crashes due to out of memory exception. Running the same application compiled in SL3, the memory used is about 200MB when all the usercontrols are loaded. Time spent to load the application in SL3 is about 10 seconds, while it takes up to 3 mins in SL4 There are no transparencies, no opacities set, no effects and animations in the layout. User controls are instantied on the fly and added or removed in the visual tree on purpose when the user switches from one screen to another. The resources are all cleaned properly when a usercontrol is removed from the visual tree to allow the GC to operate in the background. I may do something wrong but I could not figure out where exactly nail out the source of this problem. As far as I know there is no memory profiler in SL4 that can help me out to find where to look at. But again I could not be updated on new debugging tools available.

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  • errors when using c++ bison ---- in the file position.hh

    - by Eric
    firstly I'm not good at English so forgive me. I compile my program with the bison generated files in visual studio and get these errors: ...\position.hh(83): error C2589: '(' : illegal token on right side of '::' ...\position.hh(83): error C2059: syntax error : '::' ...\position.hh(83): error C2589: '(' : illegal token on right side of '::' ...\position.hh(83): error C2059: syntax error : '::' and the corresponding code is: inline void columns (int count = 1) { column = std::max (1u, column + count); } I think the problem is with std::max. If I change std::max to equivalent code then there is problem anymore, but is there a better solution instead of changing the generated code? here is the *.yy file I wrote. // // bison.yy // %skeleton "lalr1.cc" %require "2.4.2" %defines %define parser_class_name "cmd_parser" %locations %debug %error-verbose %code requires { class ParserDriver; } %parse-param { ParserDriver& driver } %lex-param { ParserDriver& driver } %union { struct ast *a; double d; struct symbol *s; struct symlist *sl; int fn; } %code { #include "helper_func.h" #include "ParserDriver.h" std::string error_msg = ""; } %token <d> NUMBER %token <s> NAME %token <fn> FUNC %token EOL %token IF THEN ELSE WHILE DO LET %token SYM_TABLE_OVERFLOW %token UNKNOWN_CHARACTER %nonassoc <fn> CMP %right '=' %left '+' '-' %left '*' '/' %nonassoc '|' UMINUS %type <a> exp stmt list explist %type <sl> symlist %{ extern int yylex(yy::cmd_parser::semantic_type *yylval, yy::cmd_parser::location_type* yylloc); %} %start calclist %% ... grammar rules ...

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  • How best to use XPath with very large XML files in .NET?

    - by glenatron
    I need to do some processing on fairly large XML files ( large here being potentially upwards of a gigabyte ) in C# including performing some complex xpath queries. The problem I have is that the standard way I would normally do this through the System.XML libraries likes to load the whole file into memory before it does anything with it, which can cause memory problems with files of this size. I don't need to be updating the files at all just reading them and querying the data contained in them. Some of the XPath queries are quite involved and go across several levels of parent-child type relationship - I'm not sure whether this will affect the ability to use a stream reader rather than loading the data into memory as a block. One way I can see of making it work is to perform the simple analysis using a stream-based approach and perhaps wrapping the XPath statements into XSLT transformations that I could run across the files afterward, although it seems a little convoluted. Alternately I know that there are some elements that the XPath queries will not run across, so I guess I could break the document up into a series of smaller fragments based on it's original tree structure, which could perhaps be small enough to process in memory without causing too much havoc. I've tried to explain my objective here so if I'm barking up totally the wrong tree in terms of general approach I'm sure you folks can set me right...

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  • svn import, dont modify revision OR modify the list of files in a transaction

    - by Vaughan Durno
    Hi Ive gained so much knowledge/insight from this site in the past few years, now im actually hoping to get some enlightenment. The scenario is as follows: You have the general structure of the repo (trunk,branches,tags) but added to the layout you have another directory called 'db_revs'. Now in the pre-commit, you take a dump of a specific database (the specifics are irrelevant) into a temporary file, say /tmp/REV.sql (REV being the HEAD revision number of the repo, or the transaction). K all is well and you can just import that temp file into the repo at /db_revs/REV.sql Now obviously that import, even tho its happening during a commit, increments the revision of the repo. So when u do a commit at some point to say 'test.php' in the trunk and it completes at say revision 159, then the pre-commit runs as it should and the DB dump gets imported but then u r sitting with a tree in the repo-browser where 'trunk' is at revision 159, and 'db_revs', which has the imported dump, is at 158 (Ive made it so that the filename matches the revision ie: 159.sql but that file is then at revision 158). NB If you're doing an import in a pre-commit, you need to add some logic to not perform the import, say by checking first for the existence of the temp file, otherwise it will cause, um, a stack overflow and your PC will quickly crawl to a stand still So I wanted to know if it was possible to make an import to not commit its changes. I realise I might be barking up the wrong tree to begin with so I have another idea of doing this so that brings me to the 2nd part of my question, would it be possible to modify the list of files that the transaction is about to commit to the repo. I know this can be done to a WC but that wont help as a WC is a checked out copy of say the trunk so im not sure how u would add a file to the 'db_revs' folder which is above trunk? Any help is greatly appreciated Cheers Vaughan

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