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  • how to manage a "resource" array efficiently

    - by Haiyuan Zhang
    The senario of my question is that one need to use a fixed size of array to keep track of certain number of "objects" . The object here can be as simply as a integer or as complex as very fancy data structure. And "keep track" here means to allocate one object when other part of the app need one instance of object and recyle it for future allocation when one instance of the object is returned .Finally ,let me use c++ to put my problme in a more descriptive way . #define MAX 65535 /* 65535 just indicate that many items should be handled . performance demanding! */ typedef struct { int item ; }Item_t; Item_t items[MAX] ; class itemManager { private : /* up to you.... */ public : int get() ; /* get one index to a free Item_t in items */ bool put(int index) ; /* recyle one Item_t indicate by one index in items */ } how will you implement the two public functions of itemManager ? it's up to you to add any private member .

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  • Autocomplete and IE7 - slowness, sluggishness as overall pagesize grows?

    - by wchrisjohnson
    Hi, I have the autocomplete plugin (http://bassistance.de/jquery-plugins/jquery-plugin-autocomplete/, version 1.1 and 1.0.2) on a project to add pieces of "equipment" to a "project". On a fresh project the plugin works great; the data returned from the database comes back FAST, you can scroll the list fast, and can select an item and move on to the next one. Once I have a project established with equipment on it, and I go to add equipment, the performance is pretty bad. It takes 4-5 seconds to get the list of data back from the server, scrolling the list is painful, and the cursor takes several seconds to settle on an item. Repainting the page after the list goes away is slow. This is occurring in IE7, latest version. FF3 and Chrome are fine, very snappy. The pagesize is about 40K overall. I'm thinking this is an issue with the IE7 Javascript engine, or an edge case with this plugin and IE7; it works quickly enough in FF3+. I would appreciate any ideas, solutions, known issues, or thoughts on how to more specifically pin this down. I'd love to post sample code, but this is a corporate app, and I'm not how useful it would be given that the server side piece cannot be shown; ie: you can't pull it down and test it like a self contained piece of code.. Thanks in advance! Chris

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  • What are the drawbacks of using PHP to create variables in my CSS stylesheet?

    - by Greg
    One significant drawback of CSS is that one can't use variables. For example, I'd like to use variables to control the location of imported CSS, and it would be awesome to create variables for colors that are used repeatedly in a design. One approach is to use a PHP file for the CSS stylesheet. In other words, create a "style.php" with... <?php header("Content-type: text/css"); ?> ...at the top of the file, and then link to it using... <link href="style.php" rel="stylesheet" type="text/css" /> ...in any file that uses these styles. So what's the catch? I think it might be performance -- I did a few quick experiments in Firefox/Firebug and as one would expect, the CSS stylesheet is cached, but the PHP stylesheet isn't. So we're paying the price of an additional GET. The other annoying thing is that TextMate does not syntax highlight properly for CSS in a .php file. Are there other drawbacks? Have you used this approach, and if so, would you recommend it?

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  • What is best practice (and implications) for packaging projects into JAR's?

    - by user245510
    What is considered best practice deciding how to define the set of JAR's for a project (for example a Swing GUI)? There are many possible groupings: JAR per layer (presentation, business, data) JAR per (significant?) GUI panel. For significant system, this results in a large number of JAR's, but the JAR's are (should be) more re-usable - fine-grained granularity JAR per "project" (in the sense of an IDE project); "common.jar", "resources.jar", "gui.jar", etc I am an experienced developer; I know the mechanics of creating JAR's, I'm just looking for wisdom on best-practice. Personally, I like the idea of a JAR per component (e.g. a panel), as I am mad-keen on encapsulation, and the holy-grail of re-use accross projects. I am concerned, however, that on a practical, performance level, the JVM would struggle class loading over dozens, maybe hundreds of small JAR's. Each JAR would contain; the GUI panel code, necessary resources (i.e. not centralised) so each panel can stand alone. Does anyone have wisdom to share?

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  • When optimizing database queries, what exactly is the relationship between number of queries and siz

    - by williamjones
    To optimize application speed, everyone always advises to minimize the number of queries an application makes to the database, consolidating them into fewer queries that retrieve more wherever possible. However, this also always comes with the caution that data transferred is still data transferred, and just because you are making fewer queries doesn't make the data transferred free. I'm in a situation where I can over-include on the query in order to cut down the number of queries, and simply remove the unwanted data in the application code. Is there any type of a rule of thumb on how much of a cost there is to each query, to know when to optimize number of queries versus size of queries? I've tried to Google for objective performance analysis data, but surprisingly haven't been able to find anything like that. Clearly this relationship will change for factors such as when the database grows in size, making this somewhat individualized, but surely this is not so individualized that a broad sense of the landscape can't be drawn out? I'm looking for general answers, but for what it's worth, I'm running an application on Heroku.com, which means Ruby on Rails with a Postgres database.

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  • Design suggestions for creating document management structure using hidden shares.

    - by focus.nz
    I need to add some document management functionality into my software. Documents will be grouped by company name and project name. The folders need to be accessed by the application using the id numbers of clients/projects, but also easily browsed by the end user using windows explorer. Clients and Projects will be stored in a database. I am thinking of having the software create the folders using the friendly name and then using a hidden share with the id number for the software to access the files. The folder structure would be something like this --Company 1 (Company-1234$) -- Project 101 (Project-101$) -- Project 102 (Project-102$) -- Project 103 (Project-103$) -- Company 2 (Company-5678$) -- Project 201 (Project-201$) -- Project 202 (Project-202$) -- Project 203 (Project-203$) So in the example above there would be a company called "Company 1" with a ID of "1234". When browsing the folders using windows explorer the user would see \\ServerName\Documents\Company1 and you could also access the same folder from \\ServerName\Documents\Company-1234$ By using the hidden share, if the company name changes or its renamed for some reason it doesn't break the link in the application because its using the hidden shared based on the ID that never changes. Will having hundreds (maybe thousands) or hidden shares on a server provide a huge performance hit? Does any one have any suggestions or alternatives to provide this feature?

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  • How to build Graceful Degradation AJAX web page?

    - by Morgan Cheng
    I want to build web page with "Graceful Degradation". That is, the web page functions even javascript is disabled. Now I have to make design decision on the format of AJAX response. If javascript is disabled, each HTTP request to server will generate HTML as response. The browser refreshes with the returned HTML. That's fine. If javascript is enabled, each AJAX HTTP request to server will generate ... well, JSON or HTML. If it is HTML, it is easy to implement. Just have javascript to replace part of page with the returned HTML. And, in server side, not much code change is needed. If it is JSON, then I have to implement JSON-to-html logic in javascript again which is almost duplicate of server side logic. Duplication is evil. I really don't like it. The benefit is that the bandwidth usage is better than HTML, which brings better performance. So, what's the best solution to Graceful Degradation? AJAX request better to return JSON or HTML?

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  • SQL 2008: Using separate tables for each datatype to return single row

    - by Thomas C
    Hi all I thought I'd be flexible this time around and let the users decide what contact information the wish to store in their database. In theory it would look as a single row containing, for instance; name, adress, zipcode, Category X, Listitems A. Example FieldType table defining the datatypes available to a user: FieldTypeID, FieldTypeName, TableName 1,"Integer","tblContactInt" 2,"String50","tblContactStr50" ... A user the define his fields in the FieldDefinition table: FieldDefinitionID, FieldTypeID, FieldDefinitionName 11,2,"Name" 12,2,"Adress" 13,1,"Age" Finally we store the actual contact data in separate tables depending on its datatype. Master table, only contains the ContactID tblContact: ContactID 21 22 tblContactStr50: ContactStr50ID,ContactID,FieldDefinitionID,ContactStr50Value 31,21,11,"Person A" 32,21,12,"Adress of person A" 33,22,11,"Person B" tblContactInt: ContactIntID,ContactID,FieldDefinitionID,ContactIntValue 41,22,13,27 Question: Is it possible to return the content of these tables in two rows like this: ContactID,Name,Adress,Age 21,"Person A","Adress of person A",NULL 22,"Person B",NULL,27 I have looked into using the COALESCE and Temp tables, wondering if this is at all possible. Even if it is: maybe I'm only adding complexity whilst sacrificing performance for benefit in datastorage and user definition option. What do you think? Best Regards /Thomas C

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  • Capturing Set Behavior with Mutating Elements

    - by Carl
    Using the Guava library, I have the following situation: SetMultimap<ImmutableFoo, Set<Foo>> setMM = HashMultimap.create(); Set<Foo> mask = Sets.newHashSet(); // ... some iteration construct { setMM.put(ImmutableFoo1, Sets.difference(SomeSetFoo1,mask)); setMM.put(ImmutableFoo1, Sets.difference(SomeSetFoo2,mask)); mask.add(someFoo); } that is, the same iteration to create the setMM is also used to create the mask - this can of course result in changes to hashCode()s and create duplicates within the SetMultimap backing. Ideally, I'd like the duplicates to drop without me having to make it happen, and avoid repeating the iteration to separately construct the multimap and mask. Any easy libraries/Set implementations to make that happen? Alternatively, can you identify a better way to drop the duplicates than: for (ImmutableFoo f : setMM.keySet()) setMM.putAll(f,setMM.removeAll(f)); revisiting the elements is probably not a performance problem, since I could combine a separate filter operation that needs to visit all the elements anyway.

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  • encrypt apache and mysql servers

    - by stormdrain
    I have a question about encrypting disks. I have 2 servers: 1 is apache for web/frontend and it talks to server 2 which is mysql. They are all for intranet only; no external access. I was looking into using PGP or GnuPG to encrypt the disks. I'm not clear, though, as to exactly how this would work. Where would the keys be stored? On the client? On apache? If there is a key on apache to access mysql, does there need to be a key for each user? If so, if key 1 is used to alter some data, would then that data be inaccessible to a user using key 2? And the apache key, would that only be accessible to users with local keys? Is encryption done on the fly? Does it degrade performance? What would be the best approach to encrypt the data on these servers, but have them accessible to users? Thanks!

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  • Most efficient way to check for DBNull and then assign to a variable?

    - by ilitirit
    This question comes up occasionally but I haven't seen a satisfactory answer. A typical pattern is (row is a DataRow): if (row["value"] != DBNull.Value) { someObject.Member = row["value"]; } My first question is which is more efficient (I've flipped the condition): row["value"] == DBNull.Value; // Or row["value"] is DBNull; // Or row["value"].GetType() == typeof(DBNull) // Or... any suggestions? This indicates that .GetType() should be faster, but maybe the compiler knows a few tricks I don't? Second question, is it worth caching the value of row["value"] or does the compiler optimize the indexer away anyway? eg. object valueHolder; if (DBNull.Value == (valueHolder = row["value"])) {} Disclaimers: row["value"] exists. I don't know the column index of the column (hence the column name lookup) I'm asking specifically about checking for DBNull and then assignment (not about premature optimization etc). Edit: I benchmarked a few scenarios (time in seconds, 10000000 trials): row["value"] == DBNull.Value: 00:00:01.5478995 row["value"] is DBNull: 00:00:01.6306578 row["value"].GetType() == typeof(DBNull): 00:00:02.0138757 Object.ReferenceEquals has the same performance as "==" The most interesting result? If you mismatch the name of the column by case (eg. "Value" instead of "value", it takes roughly ten times longer (for a string): row["Value"] == DBNull.Value: 00:00:12.2792374 The moral of the story seems to be that if you can't look up a column by it's index, then ensure that the column name you feed to the indexer matches the DataColumn's name exactly. Caching the value also appears to be nearly twice as fast: No Caching: 00:00:03.0996622 With Caching: 00:00:01.5659920 So the most efficient method seems to be: object temp; string variable; if (DBNull.Value != (temp = row["value"]) { variable = temp.ToString(); } This was a good learning experience.

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  • How would I go about sharing variables in a class with Lua?

    - by Nicholas Flynt
    I'm fairly new to Lua, I've been working on trying to implement Lua scripting for logic in a Game Engine I'm putting together. I've had no trouble so far getting Lua up and running through the engine, and I'm able to call Lua functions from C and C functions from Lua. The way the engine works now, each Object class contains a set of variables that the engine can quickly iterate over to draw or process for physics. While game objects all need to access and manipulate these variables in order for the Game Engine itself to see any changes, they are free to create their own variables, a Lua is exceedingly flexible about this so I don't forsee any issues. Anyway, currently the Game Engine side of things are sitting in C land, and I really want them to stay there for performance reasons. So in an ideal world, when spawning a new game object, I'd need to be able to give Lua read/write access to this standard set of variables as part of the Lua object's base class, which its game logic could then proceed to run wild with. So far, I'm keeping two separate tables of objects in place-- Lua spawns a new game object which adds itself to a numerically indexed global table of objects, and then proceeds to call a C++ function, which creates a new GameObject class and registers the Lua index (an int) with the class. So far so good, C++ functions can now see the Lua object and easily perform operations or call functions in Lua land using dostring. What I need to do now is take the C++ variables, part of the GameObject class, and expose them to Lua, and this is where google is failing me. I've encountered a very nice method here which details the process using tags, but I've read that this method is deprecated in favor of metatables. What is the ideal way to accomplish this? Is it worth the hassle of learning how to pass class definitions around using libBind or some equivalent method, or is there a simple way I can just register each variable (once, at spawn time) with the global lua object? What's the "current" best way to do this, as of Lua 5.1.4?

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  • Building a News-feed that comprises posts "created by user's connections" && "on the topics user is following"

    - by aklin81
    I am working on a project of Questions & Answers website that allows a user to follow questions on certain topics from his network. A user's news-feed wall comprises of only those questions that have been posted by his connections and tagged on the topics that he is following(his expertise topics). I am confused what database's datamodel would be most fitting for such an application. The project needs to consider the future provisions for scalability and high performance issues. I have been looking at Cassandra and MySQL solutions as of now. After my study of Cassandra I realized that Simple news-feed design that shows all the posts from network would be easy to design using Cassandra by executing fast writes to all followers of a user about the post from user. But for my kind of application where there is an additional filter of 'followed topics', (ie, the user receives posts "created by his network" && "on topics user is following"), I could not convince myself with a good schema design in Cassandra. I hope if I missed something because of my short understanding of cassandra, perhaps, can you please help me out with your suggestions of how this news-feed could be implemented in Cassandra ? Looking for a great project with Cassandra ! Edit: There are going to be maximum 5 tags allowed for tagging the question (ie, max 5 topics can be tagged on a question).

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  • Parsing multibyte string in PHP

    - by Petr Peller
    I would like to write a (HTML) parser based on state machine but I have doubts how to acctually read/use an input. I decided to load the whole input into one string and then work with it as with an array and hold its index as current parsing position. There would be no problems with single-byte encoding, but in multi-byte encoding each value does not represent a character, but a byte of a character. Example: $mb_string = 'žšcr'; //4 multi-byte characters in UTF-8 for($i=0; $i < 4; $i++) { echo $mb_string[$i], PHP_EOL; } Outputs: L ž L A This means I cannot iterate through the string in a loop to check single characters, because I never know if I am in the middle of an character or not. So the questions are: How do I multi-byte safe read a single character from a string in a performance friendly way? Is it good idea to work with the string as it was an array in this case? How would you read the input?

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  • Reformat SQLGeography polygons to JSON

    - by James
    I am building a web service that serves geographic boundary data in JSON format. The geographic data is stored in an SQL Server 2008 R2 database using the geography type in a table. I use [ColumnName].ToString() method to return the polygon data as text. Example output: POLYGON ((-6.1646509904325884 56.435153006374627, ... -6.1606079906751 56.4338050060666)) MULTIPOLYGON (((-6.1646509904325884 56.435153006374627 0 0, ... -6.1606079906751 56.4338050060666 0 0))) Geographic definitions can take the form of either an array of lat/long pairs defining a polygon or in the case of multiple definitions, an array or polygons (multipolygon). I have the following regex that converts the output to JSON objects contained in multi-dimensional arrays depending on the output. Regex latlngMatch = new Regex(@"(-?[0-9]{1}\.\d*)\s(\d{2}.\d*)(?:\s0\s0,?)?", RegexOptions.Compiled); private string ConvertPolysToJson(string polysIn) { return this.latlngMatch.Replace(polysIn.Remove(0, polysIn.IndexOf("(")) // remove POLYGON or MULTIPOLYGON .Replace("(", "[") // convert to JSON array syntax .Replace(")", "]"), // same as above "{lng:$1,lat:$2},"); // reformat lat/lng pairs to JSON objects } This is actually working pretty well and converts the DB output to JSON on the fly in response to an operation call. However I am no regex master and the calls to String.Replace() also seem inefficient to me. Does anyone have any suggestions/comments about performance of this?

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  • Eclipse Maven web application - can not run on server anymore

    - by wuntee
    I have an maven eclipse webapp project that I was able to right click and 'Run on server' and it would deploy on tomcat. I recently did a 'maven - Update project conifgurations' and I now can NOT deploy and run the project as a webapp. Has anyone seen this before? The only output from tomcat is as follows - it doesnt even look like its trying to deploy the application. Apr 14, 2010 3:58:54 PM org.apache.catalina.core.AprLifecycleListener init INFO: The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: .:/Library/Java/Extensions:/System/Library/Java/Extensions:/usr/lib/java Apr 14, 2010 3:58:54 PM org.apache.tomcat.util.digester.SetPropertiesRule begin WARNING: [SetPropertiesRule]{Server/Service/Engine/Host/Context} Setting property 'source' to 'org.eclipse.jst.j2ee.server:taac-web' did not find a matching property. Apr 14, 2010 3:58:54 PM org.apache.coyote.http11.Http11Protocol init INFO: Initializing Coyote HTTP/1.1 on http-8080 Apr 14, 2010 3:58:54 PM org.apache.catalina.startup.Catalina load INFO: Initialization processed in 402 ms Apr 14, 2010 3:58:54 PM org.apache.catalina.core.StandardService start INFO: Starting service Catalina Apr 14, 2010 3:58:54 PM org.apache.catalina.core.StandardEngine start INFO: Starting Servlet Engine: Apache Tomcat/6.0.24 Apr 14, 2010 3:58:54 PM org.apache.coyote.http11.Http11Protocol start INFO: Starting Coyote HTTP/1.1 on http-8080 Apr 14, 2010 3:58:54 PM org.apache.jk.common.ChannelSocket init INFO: JK: ajp13 listening on /0.0.0.0:8009 Apr 14, 2010 3:58:54 PM org.apache.jk.server.JkMain start INFO: Jk running ID=0 time=0/14 config=null Apr 14, 2010 3:58:54 PM org.apache.catalina.startup.Catalina start INFO: Server startup in 247 ms

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  • How to find minimum cut-sets for several subgraphs of a graph of degrees 2 to 4

    - by Tore
    I have a problem, Im trying to make A* searches through a grid based game like pacman or sokoban, but i need to find "enclosures". What do i mean by enclosures? subgraphs with as few cut edges as possible given a maximum size and minimum size for number of vertices that act as soft constraints. Alternatively you could say i am looking to find bridges between subgraphs, but its generally the same problem. Given a game that looks like this, what i want to do is find enclosures so that i can properly find entrances to them and thus get a good heuristic for reaching vertices inside these enclosures. So what i want is to find these colored regions on any given map. The reason for me bothering to do this and not just staying content with the performance of a simple manhattan distance heuristic is that an enclosure heuristic can give more optimal results and i would not have to actually do the A* to get some proper distance calculations and also for later adding competitive blocking of opponents within these enclosures when playing sokoban type games. Also the enclosure heuristic can be used for a minimax approach to finding goal vertices more properly. Do you know of a good algorithm for solving this problem or have any suggestions in things i should explore?

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  • Why use INCLUDE in a SQL index

    - by StarLite
    I recently encountered an index in a database I maintain that was of the form: CREATE INDEX [IX_Foo] ON [Foo] ( Id ASC ) INCLUDE ( SubId ) In this particular case, the performance problem that I was encountering (a slow SELECT filtering on both Id and SubId) could be fixed by simply moving the SubId column into the index proper rather than as an included column. This got me thinking however that I don't understand the reasoning behind included columns at all, when generally, they could simply be a part of the index itself. Even if I don't particularly care about the items being in the index itself is there any downside to having column in the index rather than simply being included. After some research, I am aware that there are a number of restrictions on what can go into an indexed column (maximum width of the index, and some column types that can't be indexed like 'image'). In these cases I can see that you would be forced to include the column in the index page data. The only thing I can think of is that if there are updates on SubId, the row will not need to be relocated if the column is included (though the value in the index would need to be changed). Is there something else that I'm missing? I'm considering going through the other indexes in the database and shifting included columns in the index proper where possible. Would this be a mistake? I'm primarily interested in MS SQL Server, but information on other DB engines is welcome also.

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  • Why is Lua considered a game language?

    - by Hoffmann
    I have been learning about Lua in the past month and I'm absolutely in love with the language, but all I see around that is built with lua are games. I mean, the syntax is very simple, there is no fuss, no special meaning characters that makes code look like regex, has all the good things about a script language and integrates so painlessly with other languages like C, Java, etc. The only down-side I saw so far is the prototype based object orientation that some people do not like (or lack of OO built-in). I do not see how ruby or python are better, surely not in performance ( http://shootout.alioth.debian.org/gp4/benchmark.php?test=all&lang=lua&lang2=python ). I was planning on writting a web app using lua with the Kepler framework and Javascript, but the lack of other projects that use lua as a web language makes me feel a bit uneasy since this is my first try with web development. Lua is considered a kids language, most of you on stackoverflow probably only know the language because of the WoW addons. I can't really see why that is... http://lua-users.org/wiki/LuaVersusPython this link provides some insights on Lua against Python, but this is clearly biased.

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  • Very interesting problem in Compact Framework

    - by Alexander
    Hi, i have a performance problem while inserting data to sqlce.I'm reading string and making inserts to My tables.In LU_MAM table,i insert 1000 records withing 8 seconds.After Mam tables i make some inserts but my largest table is CR_MUS.When i want to insert record into CR_MUS,it takes too much time.CR_MUS has 2000 records and insert takes 35 seconds.What can be reason?I use same logic in my insert functions.Do u have any idea?I use VS 2008 sp1. Dim reader As StringReader reader = New StringReader(data) cn = New SqlCeConnection(General.ConnString) cn.Open() If myTransfer.ClearTables(cn, cmd) = True Then progress = 0 '------------------------------------------ cmd = New SqlServerCe.SqlCeCommand Dim rs As SqlCeResultSet cmd.Connection = cn cmd.CommandType = CommandType.TableDirect Dim rec As SqlCeUpdatableRecord ' name of table While reader.Peek > -1 If strerr_col = "" Then satir = reader.ReadLine() ayrac = Split(satir, "|") If ayrac(0).ToString() = "LC" Then prgsbar.Maximum = Convert.ToInt32(ayrac(1)) ElseIf ayrac(0).ToString = "PPAR" Then . If ayrac(2).ToString <> General.PMVer Then ShowWaitCursor(False) txtDurum.Text = "Wrong Version" Exit Sub End If If p_POCKET_PARAMETERS = True Then cmd.CommandText = "POCKET_PARAMETERS" txtDurum.Text = "POCKET_PARAMETERS" rs = cmd.ExecuteResultSet(ResultSetOptions.Updatable) rec = rs.CreateRecord() p_POCKET_PARAMETERS = False End If strerr_col = myVERI_AL.POCKET_PARAMETERS_I(ayrac, cmd, rs, rec) prgsbar.Value += 1 ElseIf ayrac(0).ToString() = "MAM" Then If p_LU_MAM = True Then txtDurum.Text = "LU_MAM " cmd.CommandText = "LU_MAM" rs = cmd.ExecuteResultSet(ResultSetOptions.Updatable) rec = rs.CreateRecord() p_LU_MAM = False End If strerr_col = myVERI_AL.LU_MAM_I(ayrac, cmd, rs, rec) prgsbar.Value += 1 ElseIf ayrac(0).ToString = "KMUS" Then If p_CR_MUS = True Then cmd.CommandText = "CR_MUS" txtDurum.Text = "CR_MUS" rs = cmd.ExecuteResultSet(ResultSetOptions.Updatable) rec = rs.CreateRecord() p_TR_KAMPANYA_MALZEME = False End If strerr_col = myVERI_AL.CR_MUS_I(ayrac, cmd, rs, rec) prgsbar.Value += 1 end while Public Function CR_KAMPANYA_MUSTERI_I(ByVal f_Line() As String, ByRef myComm As SqlCeCommand, ByRef rs As SqlCeResultSet, ByRef rec As SqlCeUpdatableRecord) As String Try rec.SetValue(0, If(f_Line(1) = String.Empty, DirectCast(DBNull.Value, Object), f_Line(1))) rec.SetValue(1, If(f_Line(2) = String.Empty, DirectCast(DBNull.Value, Object), f_Line(2))) rec.SetValue(2, If(f_Line(3) = String.Empty, DirectCast(DBNull.Value, Object), f_Line(3))) rec.SetValue(3, If(f_Line(5) = String.Empty, DirectCast(DBNull.Value, Object), f_Line(5))) rec.SetValue(4, If(f_Line(6) = String.Empty, DirectCast(DBNull.Value, Object), f_Line(6))) rs.Insert(rec) Catch ex As Exception strerr_col = ex.Message End Try Return strerr_col End Function

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  • Writing fortran robust and "modern" code

    - by Blklight
    In some scientific environments, you often cannot go without FORTRAN as most of the developers only know that idiom, and there is lot of legacy code and related experience. And frankly, there are not many other cross-platform options for high performance programming ( C++ would do the task, but the syntax, zero-starting arrays, and pointers are too much for most engineers ;-) ). I'm a C++ guy but I'm stuck with some F90 projects. So, let's assume a new project must use FORTRAN (F90), but I want to build the most modern software architecture out of it. while being compatible with most "recent" compilers (intel ifort, but also including sun/HP/IBM own compilers) So I'm thinking of imposing: global variable forbidden, no gotos, no jump labels, "implicit none", etc. "object-oriented programming" (modules with datatypes + related subroutines) modular/reusable functions, well documented, reusable libraries assertions/preconditions/invariants (implemented using preprocessor statements) unit tests for all (most) subroutines and "objects" an intense "debug mode" (#ifdef DEBUG) with more checks and all possible Intel compiler checks possible (array bounds, subroutine interfaces, etc.) uniform and enforced legible coding style, using code processing tools C stubs/wrappers for libpthread, libDL (and eventually GPU kernels, etc.) C/C++ implementation of utility functions (strings, file operations, sockets, memory alloc/dealloc reference counting for debug mode, etc.) ( This may all seem "evident" modern programming assumptions, but in a legacy fortran world, most of these are big changes in the typical programmer workflow ) The goal with all that is to have trustworthy, maintainable and modular code. Whereas, in typical fortran, modularity is often not a primary goal, and code is trustworthy only if the original developer was very clever, and the code was not changed since then ! (i'm a bit joking here, but not much) I searched around for references about object-oriented fortran, programming-by-contract (assertions/preconditions/etc.), and found only ugly and outdated documents, syntaxes and papers done by people with no large-scale project involvement, and dead projects. Any good URL, advice, reference paper/books on the subject?

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  • A map and set which uses contiguous memory and has a reserve function

    - by edA-qa mort-ora-y
    I use several maps and sets. The lack of contiguous memory, and high number of (de)allocations, is a performance bottleneck. I need a mainly STL-compatbile map and set class which can use a contiguous block of memory for internal objects (or multiple blocks). It also needs to have a reserve function so that I can preallocate for expected sizes. Before I write my own I'd like to check what is available first. Is there something in Boost which does this? Does somebody know of an available implementation elsewhere? Intrusive collection types are not usable here as the same objects need to exist in several collections. As far as I know STL memory pools are per-type, not per instance. These global pools are not efficient with respect to memory locality in mutli-cpu/core processing. Object pools don't work as the types will be shared between instance but their pool should not. In many cases a hash map may be an option in some cases.

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  • RANDOM Number Generation in C

    - by CVS-2600Hertz-wordpress-com
    Recently i have begun development of a simple game. It is improved version of an earlier version that i had developed. Large part of the game's success depends on Random number generation in different modes: MODE1 - Truly Random mode myRand(min,max,mode=1); Should return me a random integer b/w min & max. MODE2 - Pseudo Random : Token out of a bag mode myRand(min,max,mode=2); Should return me a random integer b/w min & max. Also should internally keep track of the values returned and must not return the same value again until all the other values are returned atleast once. MODE3 - Pseudo Random : Human mode myRand(min,max,mode=3); Should return me a random integer b/w min & max. The randomisation ought to be not purely mathematically random, rather random as user perceive it. How Humans see RANDOM. * Assume the code is time-critical (i.e. any performance optimisations are welcome) * Pseudo-code will do but an implementation in C is what i'm looking for. * Please keep it simple. A single function should be sufficient (thats what i'm looking for) Thank You

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  • C#: Accessing PerformanceCounters for the ".NET CLR Memory category"

    - by Mads Ravn
    I'm trying to access the performance counters located in ".NET CLR Memory category" through C# using the PerformanceCounter class. However a cannot instantiate the categories with what I would expect was the correct category/counter name new PerformanceCounter(".NET CLR Memory", "# bytes in all heaps", Process.GetCurrentProcess().ProcessName); I tried looping through categories and counters using the following code string[] categories = PerformanceCounterCategory.GetCategories().Select(c => c.CategoryName).OrderBy(s => s).ToArray(); string toInspect = string.Join(",\r\n", categories); System.Text.StringBuilder interestingToInspect = new System.Text.StringBuilder(); string[] interestingCategories = categories.Where(s => s.StartsWith(".NET") || s.Contains("Memory")).ToArray(); foreach (string interestingCategory in interestingCategories) { PerformanceCounterCategory cat = new PerformanceCounterCategory(interestingCategory); foreach (PerformanceCounter counter in cat.GetCounters()) { interestingToInspect.AppendLine(interestingCategory + ":" + counter.CounterName); } } toInspect = interestingToInspect.ToString(); But could not find anything that seems to match. Is it not possible to observe these values from within the CLR or am I doing something wrong. The environment, should it matter, is .NET 4.0 running on a 64-bit windows 7 box.

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  • getting proxies of the correct type in nhibernate

    - by Nir
    I have a problem with uninitialized proxies in nhibernate The Domain Model Let's say I have two parallel class hierarchies: Animal, Dog, Cat and AnimalOwner, DogOwner, CatOwner where Dog and Cat both inherit from Animal and DogOwner and CatOwner both inherit from AnimalOwner. AnimalOwner has a reference of type Animal called OwnedAnimal. Here are the classes in the example: public abstract class Animal { // some properties } public class Dog : Animal { // some more properties } public class Cat : Animal { // some more properties } public class AnimalOwner { public virtual Animal OwnedAnimal {get;set;} // more properties... } public class DogOwner : AnimalOwner { // even more properties } public class CatOwner : AnimalOwner { // even more properties } The classes have proper nhibernate mapping, all properties are persistent and everything that can be lazy loaded is lazy loaded. The application business logic only let you to set a Dog in a DogOwner and a Cat in a CatOwner. The Problem I have code like this: public void ProcessDogOwner(DogOwner owner) { Dog dog = (Dog)owner.OwnedAnimal; .... } This method can be called by many diffrent methods, in most cases the dog is already in memory and everything is ok, but rarely the dog isn't already in memory - in this case I get an nhibernate "uninitialized proxy" but the cast throws an exception because nhibernate genrates a proxy for Animal and not for Dog. I understand that this is how nhibernate works, but I need to know the type without loading the object - or, more correctly I need the uninitialized proxy to be a proxy of Cat or Dog and not a proxy of Animal. Constraints I can't change the domain model, the model is handed to me by another department, I tried to get them to change the model and failed. The actual model is much more complicated then the example and the classes have many references between them, using eager loading or adding joins to the queries is out of the question for performance reasons. I have full control of the source code, the hbm mapping and the database schema and I can change them any way I want (as long as I don't change the relationships between the model classes). I have many methods like the one in the example and I don't want to modify all of them. Thanks, Nir

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