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  • WinForms GDI+ Polygon Events and custom shaped panels

    - by JD
    I have converted postcode boundary polygons to point data (point[] for each polygon) from GIS Shape Files. I am wanting to show this in a c# windows forms application. I have managed to show this using the System.Drawing (GDI+) DrawPolygon() method. Graphics g = this.CreateGraphics(); Pen pen = new Pen(Color.Black); Brush brush = new SolidBrush(Color.FromArgb(255,255,o)); PointF[] ptr = { point data here }; g.FillPolygon(brush, ptr); g.DrawPolygon(pen, ptr); Is it possible to add events to a drawn polygon? If so how do I do this for individual polygons. For example, click on a postcode polygon and a messagebox shows information about the postcode. Secondly, would it be easier to make a custom control inheriting the winforms panel. Is there a way to shape the border of a winforms panel control using a set of points? Postcode objects are serialised and stored in the filesystem.

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  • Algorithms for finding a numerical record in a list of ordered numbers

    - by Ankur
    I have a list of incomplete ordered numbers. I want to find a particular number with as few steps as possible. Are there any improvements on this algorithm, I assume you can count the set size without difficulty - it will be stored and updated every time a new item is added. Your object is to get your cursor over the value x The first number (smallest) is s, and the last number (greatest) is g. Take the midpoint m1 of the set: calculate is x < m1, If yes then s <= x < m1 If no then m1 < x <= g If m1 = x then you're done. Keep repeating till you find x. Basically dividing the set into two parts with each iteration till you hit x. The purpose is to retrieve a numerical id from a very large table to then find the associated other records. I would imagine this is the most trivial kind of indexing available, are there improvements?

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  • SSIS - How do I use a resultset as input in a SQL task and get data types right?

    - by thursdaysgeek
    I am trying to merge records from an Oracle database table to my local SQL table. I have a variable for the package that is an Object, called OWell. I have a data flow task that gets the Oracle data as a SQL statment (select well_id, well_name from OWell order by Well_ID), and then a conversion task to convert well_id from a DT_STR of length 15 to a DT_WSTR; and convert well_name from a DT_STR of length 15 to DT_WSTR of length 50. That is then stored in the recordset OWell. The reason for the conversions is the table that I want to add records to has an identity field: SSIS shows well_id as a DT_WSTR of length 15, well_name a DT_WSTR of length 50. I then have a SQL task that connects to the local database and attempts to add records that are not there yet. I've tried various things: using the OWell as a result set and referring to it in my SQL statement. Currently, I have the ResultSet set to None, and the following SQL statment: Insert into WELL (WELL_ID, WELL_NAME) Select OWELL_ID, OWELL_NAME from OWell where OWELL_ID not in (select WELL.WELL_ID from WELL) For Parameter Mapping, I have Paramater 0, called OWell_ID, from my variable User::OWell. Parameter 1, called OWell_Name is from the same variable. Both are set to VARCHAR, although I've also tried NVARCHAR. I do not have a Result set. I am getting the following error: Error: 0xC002F210 at Insert records to FLEDG, Execute SQL Task: Executing the query "Insert into WELL (WELL_ID, WELL_NAME) Select OWELL..." failed with the following error: "An error occurred while extracting the result into a variable of type (DBTYPE_STR)". Possible failure reasons: Problems with the query, "ResultSet" property not set correctly, parameters not set correctly, or connection not established correctly. I don't think it's a data type issue, but rather that I somehow am not using the resultset properly. How, exactly, am I supposed to refer to that recordset in my SQL task, so that I can use the two recordset fields and add records that are missing?

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  • Why use SQL database?

    - by martinthenext
    I'm not quite sure stackoverflow is a place for such a general question, but let's give it a try. Being exposed to the need of storing application data somewhere, I've always used MySQL or sqlite, just because it's always done like that. As it seems like the whole world is using these databases, most of all software products, frameworks, etc. It is rather hard for a beginning developer like me to ask a question - why? Ok, say we have some object-oriented logic in our application, and objects are related to each other somehow. We need to map this logic to the storage logic, so we need relations between database objects too. This leads us to using relational database and I'm ok with that - to put it simple, our database rows sometimes will need to have references to other tables' rows. But why do use SQL language for interaction with such a database? SQL query is a text message. I can understand this is cool for actually understanding what it does, but isn't it silly to use text table and column names for a part of application that no one ever seen after deploynment? If you had to write a data storage from scratch, you would have never used this kind of solution. Personally, I would have used some 'compiled db query' bytecode, that would be assembled once inside a client application and passed to the database. And it surely would name tables and colons by id numbers, not ascii-strings. In the case of changes in table structure those byte queries could be recompiled according to new db schema, stored in XML or something like that. What are the problems of my idea? Is there any reason for me not to write it myself and to use SQL database instead?

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  • ASP.NET MVC solution to a forms application?

    - by Gloria Huang
    Hello, We're building a survey system and utilising ASP.NET MVC and wondered if anyone can offer suggestions on the architecture. Here's the problem we're trying to solve. Essentially an agency sends out several surveys every year. They're very structured and not like SurveyMonkey style of surveys - they're actually applications of feedback. Much like a Visa Application there are lots of things they need to do and sometimes it takes them 2-3 weeks to fill it out. They can upload files (proofs of purchase etc - PDF/JPG) and also multiple "items". Eg. Say for instance they've worked for McDonalds, there could be 20 different franchises, they build a list of locations they've worked. 3 weeks later there could be another 3 new locations and 2 may have closed down. So we need to ensure the forms are able to handle those situations. The forms themselves (markup and data) change every year - I should mention that this for a taxation/finance/budget system. We were thinking of using MVC, using Xml to store the data (temporarily), XSD to validate the data, XSL to transform the data to presentable markup (for them to fill out) and then once they "Submit" an application it gets stored into the DB in relevant areas. When the user starts the application process, they can save the progress so far (we validate whatever they entred and ignore any they havent), save it as an Xml blob and store in the DB. When they're finally ready to submit it, then we do a full validation and upload the files and store them securely (it has their business proofs and accounting statements) and then run some workflows. What I'm really concerned about is how to manage changing forms versions (a year later). How are form/application systems written these days? We have 2 months to pull this off and about 30 forms to deliver. So 30xXML, 30xXSD, 30xXSL.

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  • Active Directory - Query Group for all machines

    - by Ben Cawley
    Hi, I'm trying to obtain a list of all Machines that are members of a known group. I have the group GUID and am constructing a query using the "memberof=" format and filtering by ObjectClass. This works fine but doesn't return machines if the PrimaryGroup attribute of a machine is set to be the known group. In this case, that machine won't be returned. I've found the explanation of why this is in the following link (See Joe Kaplan's response) http://www.eggheadcafe.com/software/aspnet/29773581/active-directory-query-c.aspx Unfortunately the outlined answer is how to obtain the list of groups from a given user. I'd like to do the reverse and from a given group obtain the list of machines. It seems that the PrimaryGroup information is stored on the Machine/User side so I'm not sure if what I want to do is even possible. I had thought I would be able to query the TokenGroup attribute of the known group and then construct a query to return all machines that have the TokenGroup attribute set but it seems that not all groups have this attribute. Does anyone have any ideas or suggestions? If any clarification is needed let me know! Cheers, Ben

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  • Sqlite3 "chained" query

    - by Arrieta
    I need to create a configuration file from a data file that looks as follows: MAN1_TIME '01-JAN-2010 00:00:00.0000 UTC' MAN1_RX 123.45 MAN1_RY 123.45 MAN1_RZ 123.45 MAN1_NEXT 'MAN2' MAN2_TIME '01-MAR-2010 00:00:00.0000 UTC' MAN2_RX 123.45 [...] MAN2_NEXT 'MANX' [...] MANX_TIME [...] This file describes different "legs" of a trajectory. In this case, MAN1 is chained to MAN2, and MAN2 to MANX. In the original file, the chains are not as obvious (i.e., they are non-sequential). I've managed to read the file and store in an Sqlite3 database (I'm using the Python interface). The table is stored with three columns: Id, Par, and Val; for instance, Id='MAN1', Par='RX', and Val='123.45'. I'm interested in querying such database for obtaining the information related to 'n' legs. In English, that would be: "Select RX,RY,RZ for the next five legs starting on MAN1" So the query would go to MAN1, retrieve RX, RY, RZ, then read the parameter NEXT and go to that Id, retrieve RX, RY, RZ; read the parameter NEXT; go to that one ... like this five times. How can I pass such query with "dynamic parameters"? Thank you.

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  • How do you save images to a Blackberry device via HttpConnection?

    - by Kai
    My script fetches xml via httpConnection and saves to persistent store. No problems there. Then I loop through the saved data to compose a list of image url's to fetch via queue. Each of these requests calls the httpConnection thread as so ... public synchronized void run() { HttpConnection connection = (HttpConnection)Connector.open("http://www.somedomain.com/image1.jpg"); connection.setRequestMethod("GET"); String contentType = connection.getHeaderField("Content-type"); InputStream responseData = connection.openInputStream(); connection.close(); outputFinal(responseData, contentType); } public synchronized void outputFinal(InputStream result, String contentType) throws SAXException, ParserConfigurationException, IOException { if(contentType.startsWith("text/")) { // bunch of xml save code that works fine } else if(contentType.equals("image/png") || contentType.equals("image/jpeg") || contentType.equals("image/gif")) { // how to save images here? } else { //default } } What I can't find any good documentation on is how one would take the response data and save it to an image stored on the device. Maybe I just overlooked something very obvious. Any help is very appreciated. Thanks

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  • (EXCEL)VBA Spin button which steps through in an sql databases date time

    - by Gulredy
    I have an sql Database table in MySQL which have lots of rows with varied date time values. For example: 2012-08-21 10:10:00 <-- with these date there are around 12 rows 2012-08-21 15:31:00 <-- with these date there are around 5 rows 2012-08-22 11:40:00 <-- with these date there are around 10 rows 2012-08-22 12:17:00 <-- with these date there are around 9 rows 2012-08-22 12:18:00 <-- with these date there are around 7 rows 2012-08-25 07:21:00 <-- with these date there are around 6 rows If the user clicks on the SpinButton1_SpinUp() or SpinButton1_SpinDown() button then it should do the following: The SpinButton1_SpinUp() button should filter out those data from an sql table which is the next after what we are currently on now. Example: We have currently selected: 2012-08-21 15:31:00. The user hits the SpinUp button then the program selects those date from the database, which is the next higher value like this one: 2012-08-22 11:40:00. So the user hits the SpinUp button the data which is selected in the database will change from those with date: 2012-08-21 15:31:00 to those with date: 2012-08-22 11:40:00 The SpinButton1_SpinDown() will do exactly the reverse of the SpinUp button. When the user hits the SpinDown button the data which is selected in the database will change from those with date: 2012-08-21 15:31:00 to those with date 2012-08-21 10:10:00 So I think the date which we are currently on, should be stored in a variable. But on button hit not every bigger or lower data should be selected in the database, only those which are the closest bigger or the closest lower date. How can I do this? I hope I described my problem understandable. My native language is not english, so misunderstandings can occur! Please ask if you don't understand something! Thank you for reading!

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  • Entity Framework self referencing entity deletion.

    - by Viktor
    Hello. I have a structure of folders like this: Folder1 Folder1.1 Folder1.2 Folder2 Folder2.1 Folder2.1.1 and so on.. The question is how to cascade delete them(i.e. when remove folder2 all children are also deleted). I can't set an ON DELETE action because MSSQL does not allow it. Can you give some suggesions? UPDATE: I wrote this stored proc, can I just leave it or it needs some modifications? SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE PROCEDURE sp_DeleteFoldersRecursive @parent_folder_id int AS BEGIN SET NOCOUNT ON; IF @parent_folder_id = 0 RETURN; CREATE TABLE #temp(fid INT ); DECLARE @Count INT; INSERT INTO #temp(fid) SELECT FolderId FROM Folders WHERE FolderId = @parent_folder_id; SET @Count = @@ROWCOUNT; WHILE @Count > 0 BEGIN INSERT INTO #temp(fid) SELECT FolderId FROM Folders WHERE EXISTS (SELECT FolderId FROM #temp WHERE Folders.ParentId = #temp.fid) AND NOT EXISTS (SELECT FolderId FROM #temp WHERE Folders.FolderId = #temp.fid); SET @Count = @@ROWCOUNT; END DELETE Folders FROM Folders INNER JOIN #temp ON Folders.FolderId = #temp.fid; DROP TABLE #temp; END GO

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  • android odbc connection

    - by Vijay Kumar
    i want to connect odbc connection for my android application. Here in my program i'm using oracle database 11g and my table name is sample. After i run the program close the emulator open the database the values could not be stored. Please give one solution or any changes in my program or connection string. package com.odbc; import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import android.app.Activity; import android.os.Bundle; public class OdbcActivity extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); String first="vijay"; String last="kumar"; try { DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver()); Connection con=DriverManager.getConnection("jdbc:oracle:thin:@localshot:1521:XE","system","vijay"); PreparedStatement pst=con.prepareStatement("insert into sample(first,last) values(?,?"); pst.setString(1,first); pst.setString(2,last); pst.executeUpdate(); } catch(Exception e) { System.out.println("Exception:"+e); } } }

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  • Setting up a multi-site CMS, collecting thoughts about the DB schema

    - by Ben Fransen
    Hello all, I'm collecting some thoughts about creating a multisite CMS. In my opinion there are two major approaches. All data is stored into 1 database, giving me the advantage of single point of updates; Seperated databases, so each client has its own database. Giving me the advantage to measure bandwith. Option 1 gives me the disadvantage of measuring bandwith while option is giving me the disadvantage of a single point of update structure. Are there any generic approaches for creating a sort of update system? So my clients can download a small package (maybe a zip with a conf file to tell the updatescript where to put all the files and how to extend the database??) Do you guys have some thougths about the best solution for a situation like this? I have my own webserver, full access to all resources and I'm developing in PHP with MySQL as DBMS. I hope to hear from you and I surely appreciate any effort you make to help me further! Greets from Holland, Ben Fransen

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  • how to access a type defined in one .ml file in another .ml file

    - by user339261
    Hi, I m very new to ocaml and i m facing the problem below, In a.ml a record type t is defined and is also defined transparently in a.mli, i.e. in d interface so that the type definition is available to all other files. a.ml also has a function, func, which returns a list of t. Now in another file, b.ml i m calling func, now obviously ocaml compiler wud nt be able to infer d type of objects stored in d list, for compiler its just a list. so in b.ml, i hav something like dis, let tlist = A.func in let vart = List.hd tlist in printf "%s\n" vart.name (name is a field in record t) Now here i get a compiler error sayin "Unbound record field label name" which makes sense as compiler can't infer d type of vart. my first question: how do I explicitly provide d type of vart as t here? i tried doing "let vart:A.t = " but got the same error. I also tried creating another function to fetch the first element of d list and mentioning return type as A.t, but then i got the "Unbound value A.t". I did this: let firstt = function [] - 0 | x :: _ - A.t x ;; The problem is compiler is unable to recognize A.t (a type) in b.ml but is able to recognize function A.func. If I remove A.t from the b.ml, i don'get any compiler errors. Please help, its urgent work. Thanks in advance! ~Tarun

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  • Need to format character precedence in Strings.

    - by Christian
    I'm currently writing a Roman Numeral Converter for the fun of it. The problem works up to the aforementioned character precedence. Since Roman Numerals are not positional, i.e. III does not symbolize 1*whatever base^2 + 1*whatever base^1 + 1*whatever base^0. That of course makes it hard when somebody types in XIV and I need to make sure that the I is not added in this case, but rather subtracted. I'm not sure how to do this. What would be the best approach to tackle this? I have both the Roman Symbols and their respective decimal numbers stored in arrays: const char cRomanArray[] = "IVXLCDM"; const int romanArray[] = { 1, 5, 10, 50, 100, 500, 1000 }; so it wouldn't be too hard for me to brute-force the damn thing by simply checking the precedence within the array, i.e. if the symbol is smaller than the next symbol, i.e. in the exampe 'XIV' if 'I' is smaller than 'V', in which case it would be because I have ordered them in the array, then I could make it subtract the value instead of add. But this seems like a very ugly solution. Are there perhaps any better ones? I was thinking something along the lines of Regular Expressions maybe( forgive me if that sounds like a horrible idea, I haven't used RegExp yet, but it sounds like it could do what I need, and that's to determine the characters in a string.)

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  • Is it possible to store controls(Panel) as object, serialize it and store it as a file?

    - by ikky
    The topic says it all. Using Compact Framework C# I'm tiling (order/sequence is important) some images that i download from an url, into a Panel(each image is a PictureBox). This can be a huge process, and may take some time. Therefor i only want the user to download the images and tile them once. So the next time the user uses the Tile Application, the Panel that was created the first time is already stored in a file and is loaded from that file. So what i want is a method to store a Panel as a file. Is this possible, or do you think i should do it another way? I've tried something like this: BinaryWriter panelStorage = new BinaryWriter(new FileStream("imagePanel.panel", FileMode.OpenOrCreate, FileAccess.Write, FileShare.None)); Byte[] bImageObject = new Byte[20000]; bImageObject = (byte[])(object)this.imagePanel; panelStorage .Write(bMapObject); panelStorage .Close(); But the casting was not very legal :P "InvalidCastException" Can anyone help me with this problem? Thank you in advance!

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  • Best approach to storing image pixels in bottom-up order in Java

    - by finnw
    I have an array of bytes representing an image in Windows BMP format and I would like my library to present it to the Java application as a BufferedImage, without copying the pixel data. The main problem is that all implementations of Raster in the JDK store image pixels in top-down, left-to-right order whereas BMP pixel data is stored bottom-up, left-to-right. If this is not compensated for, the resulting image will be flipped vertically. The most obvious "solution" is to set the SampleModel's scanlineStride property to a negative value and change the band offsets (or the DataBuffer's array offset) to point to the top-left pixel, i.e. the first pixel of the last line in the array. Unfortunately this does not work because all of the SampleModel constructors throw an exception if given a negative scanlineStride argument. I am currently working around it by forcing the scanlineStride field to a negative value using reflection, but I would like to do it in a cleaner and more portable way if possible. e.g. is there another way to fool the Raster or SampleModel into arranging the pixels in bottom-up order but without breaking encapsulation? Or is there a library somewhere that will wrap the Raster and SampleModel, presenting the pixel rows in reverse order? I would prefer to avoid the following approaches: Copying the whole image (for performance reasons. The code must process hundreds of large (= 1Mpixels) images per second and although the whole image must be available to the application, it will normally access only a tiny (but hard-to-predict) portion of the image.) Modifying the DataBuffer to perform coordinate transformation (this actually works but is another "dirty" solution because the buffer should not need to know about the scanline/pixel layout.) Re-implementing the Raster and/or SampleModel interfaces from scratch (but I have a hunch that I will be unable to avoid this.)

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  • Forms Auth: have different credentials for a subdirectory?

    - by Fyodor Soikin
    My website has forms authentication, and all is well. Now I want to create a subdirectory and have it also password-protected, but! I need the subdirectory to use a completely different set of logins/passwords than the whole website uses. Say, for example, I have users for the website stored in the "Users" table in a database. But for the subdirectory, I want the users to be taken from the "SubdirUsers" table. Which probably has a completely different structure. Consequently, I need the logins to be completely parallel, as in: Logging into the whole website does not make you logged into the subdirectory as well Clicking "logout" on the whole website does not nullify your login in the subdirectory And vice versa I do not want to create a separate virtual application for the subdirectory, because I want to share all libraries, user controls, as well as application state and cache. In other words, it has to be the same application. I also do not want to just add a flag to the "Users" table indicating whether this is a whole website user or the subdirectory user. User lists have to come from different sources. For now, the only option that I see is to roll my own Forms Auth for the subdirectory. Anybody can propose a better alternative?

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  • Are there some cases where Python threads can safely manipulate shared state?

    - by erikg
    Some discussion in another question has encouraged me to to better understand cases where locking is required in multithreaded Python programs. Per this article on threading in Python, I have several solid, testable examples of pitfalls that can occur when multiple threads access shared state. The example race condition provided on this page involves races between threads reading and manipulating a shared variable stored in a dictionary. I think the case for a race here is very obvious, and fortunately is eminently testable. However, I have been unable to evoke a race condition with atomic operations such as list appends or variable increments. This test exhaustively attempts to demonstrate such a race: from threading import Thread, Lock import operator def contains_all_ints(l, n): l.sort() for i in xrange(0, n): if l[i] != i: return False return True def test(ntests): results = [] threads = [] def lockless_append(i): results.append(i) for i in xrange(0, ntests): threads.append(Thread(target=lockless_append, args=(i,))) threads[i].start() for i in xrange(0, ntests): threads[i].join() if len(results) != ntests or not contains_all_ints(results, ntests): return False else: return True for i in range(0,100): if test(100000): print "OK", i else: print "appending to a list without locks *is* unsafe" exit() I have run the test above without failure (100x 100k multithreaded appends). Can anyone get it to fail? Is there another class of object which can be made to misbehave via atomic, incremental, modification by threads? Do these implicitly 'atomic' semantics apply to other operations in Python? Is this directly related to the GIL?

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  • how to verify browser IP for server-side web service

    - by Anthony
    I have a web service that needs to be able to verify the end-user's IP that called the server-script that is requesting the web service. Simple layout: Person A goes to Webpage B. Webpage B calls Web Service C to get some info on Person A. Web Service C won't give Webpage B the requested information without confirmation that the request originated from Person A's IP and not someone who has stolen Person A's session. I'm thinking that for a browser-based solution, the original site (Webpage B) can open an iframe that goes to the Web Service's authentication page. A key of some kind is passed to the browser which will some how indicate both the user's IP and Web Page B's IP, so that the Web Service can confirm that no one has nabbed anything. I have two challenges, but I'll stick to the more immediate one first: I'm not sure if my browser-based plan really makes sense. If someone steals the session cookie, how is the Web Service going to know? Would this cookie be held be Web Page B and thus be harder to steal? Is it a sound assumption that a cookie or key held by the server only and not the browser is safe? Also, would the web service, based on the iframe initial connection, be expecting the server/user-ip combo? What I mean is, does the session key provided via the iframe get stored by the web service and the Web Site B shows it has a match? Or is the session key more generic, meaning the web service is passed the key by Website B and the Web Service verifies that this is a valid session key based on what a valid session key should look like?

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  • Semaphore race condition?

    - by poindexter12
    I have created a "Manager" class that contains a limited set of resources. The resources are stored in the "Manager" as a Queue. I initialize the Queue and a Semaphore to the same size, using the semaphore to block a thread if there are no resources available. I have multiple threads calling into this class to request a resource. Here is the psuedo code: public IResource RequestResource() { IResource resource = null; _semaphore.WaitOne(); lock (_syncLock) { resource = _resources.Dequeue(); } return resource; } public void ReleaseResource(IResource resource) { lock (_syncLock) { _resources.Enqueue(resource); } _semaphore.Release(); } While running this application, it seems to run fine for a while. Then, it seems like my Queue is giving out the same object. Does this seem like its possible? I'm pulling my hair out over here, and any help would be greatly appreciated. Feel free to ask for more information if you need it. Thanks!

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  • priority queue with limited space: looking for a good algorithm

    - by SigTerm
    This is not a homework. I'm using a small "priority queue" (implemented as array at the moment) for storing last N items with smallest value. This is a bit slow - O(N) item insertion time. Current implementation keeps track of largest item in array and discards any items that wouldn't fit into array, but I still would like to reduce number of operations further. looking for a priority queue algorithm that matches following requirements: queue can be implemented as array, which has fixed size and _cannot_ grow. Dynamic memory allocation during any queue operation is strictly forbidden. Anything that doesn't fit into array is discarded, but queue keeps all smallest elements ever encountered. O(log(N)) insertion time (i.e. adding element into queue should take up to O(log(N))). (optional) O(1) access for *largest* item in queue (queue stores *smallest* items, so the largest item will be discarded first and I'll need them to reduce number of operations) Easy to implement/understand. Ideally - something similar to binary search - once you understand it, you remember it forever. Elements need not to be sorted in any way. I just need to keep N smallest value ever encountered. When I'll need them, I'll access all of them at once. So technically it doesn't have to be a queue, I just need N last smallest values to be stored. I initially thought about using binary heaps (they can be easily implemented via arrays), but apparently they don't behave well when array can't grow anymore. Linked lists and arrays will require extra time for moving things around. stl priority queue grows and uses dynamic allocation (I may be wrong about it, though). So, any other ideas?

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  • what data structure should I use for hash lookup as well as binary search?

    - by zebraman
    I am working on a school homework. I have a list of names. I want to be able to perform binary search on these names (find all names between a lower and upper bound) for first name as well as last name, and perform keyword searches as well (this will be accomplished using hashing. For example, if I have the names Garfield Cat Snoopy Dog Captain Crunch Fat Cat then a binary search of first names (C,H) will return Captain Crunch, Fat Cat, and Garfield Cat. A binary search of last names (Cr,D) will return Captain Crunch. A keyword search of 'cat' will return Fat Cat and Garfield Cat. I understand binary search will only work on a sorted list, but since I am planning on searching two different criteria, I will have to sort the list by last name or first name depending on what I'm searching for. I feel like it will be too inefficient to have to resort the list each time I want to perform a new binary search. Would it just be better for me to set up and maintain two sorted lists (one for sorted by first name, one for sorted by last name)? Also, for hashing, will I have to set up a different table of names for that as well? I understand each keyword will hash to some value determined by a hash function, and this value (or key) is a table address where the corresponding names are stored. So I just want to know what would be the best way to solve this problem? Maintaining separate structures, or is there a way to efficiently do everything I want with just one data structure?

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  • Should this even be a has_many :through association?

    - by GoodGets
    A Post belongs_to a User, and a User has_many Posts. A Post also belongs_to a Topic, and a Topic has_many Posts. class User < ActiveRecord::Base has_many :posts end class Topic < ActiveRecord::Base has_many :posts end class Post < ActiveRecord::Base belongs_to :user belongs_to :topic end Well, that's pretty simple and very easy to set up, but when I display a Topic, I not only want all of the Posts for that Topic, but also the user_name and the user_photo of the User that made that Post. However, those attributes are stored in the User model and not tied to the Topic. So how would I go about setting that up? Maybe it can already be called since the Post model has two foreign keys, one for the User and one for the Topic? Or, maybe this is some sort of "one-way" has_many through assiociation. Like the Post would be the join model, and a Topic would has_many :users, :through = :posts. But the reverse of this is not true. Like a User does NOT has_many :topics. So would this even need to be has_many :though association? I guess I'm just a little confused on what the controller would look like to call both the Post and the User of that Post for a give Topic. Edit: Seriously, thank you to all that weighed in. I chose tal's answer because I used his code for my controller; however, I could have just as easily chosen either j.'s or tim's instead. Thank you both as well. This was so damn simple to implement, and I think today marks the day that I'm beginning to fall in love with rails.

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  • ETL , Esper or Drools?

    - by geoaxis
    Hello, The question environment relates to JavaEE, Spring I am developing a system which can start and stop arbitrary TCP (or other) listeners for incoming messages. There could be a need to authenticate these messages. These messages need to be parsed and stored in some other entities. These entities model which fields they store. So for example if I have property1 that can have two text fields FillLevel1 and FillLevel2, I could receive messages on TCP which have both fill levels specified in text as F1=100;F2=90 Later I could add another filed say FillLevel3 when I start receiving messages F1=xx;F2=xx;F3=xx. But this is a conscious decision on the part of system modeler. My question is what do you think is better to use for parsing and storing the message. ETL (using Pantaho, which is used in other system) where you store the raw message and use task executor to consume them one by one and store the transformed messages as per your rules. One could use Espr or Drools to do the same thing , storing rules and executing them with timer, but I am not sure how dynamic you could get with making rules (they have to be made by end user in a running system and preferably in most user friendly way, ie no scripts or code, only GUI) The end user should be capable of changing the parse rules. It is also possible that end user might want to change the archived data as well (for example in the above example if a new value of FillLevel is added, one would like to put a FillLevel=-99 in the previous values to make the data consistent). Please ask for explanations, I have the feeling that I need to revise this question a bit. Thanks

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  • PHP, MySQL: Receive email, auto search in DB & send email based on the results

    - by Devner
    Hi all, Visitors can contact staff by means of contact form (visitor needs to submit email as well). This will be stored in DB. Now considering that staff responds to this message, the reply from the staff would be sent to the visitors email directly. Say if the user wants to follow up on the message sent by the staff, I would like the visitor to just hit the reply button in his email service & send me his questions on the same topic, but just retain the ID in the Subject line. So when the visitor send this email, I would like to receive the email & at the same time, try to search in my DB if the ID that is present in the email subject, actually exists in the system. If yes, that would be sent back to the same staff member who handled the response previously or it would be assigned to a new staff member. That being said, I was thinking of how to do this. The part where I am really held up is when the staff receives the actual email from the visitors email, how can I check the DB? Say I am/staff is receiving emails at [email protected]. When visitor sends reply email, then it would be sent to [email protected]. How can I check to see if the ID in the subject line of the email that I received at [email protected], actually exists in my DB in my website? This is where I am really stuck. Looking forward for your replies. Thank you.

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