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• A problem with connected points and determining geometry figures based on points' location analysis

  - by StolePopov

  In school we have a really hard problem, and still no one from the students has solved it yet. Take a look at the picture below: http://d.imagehost.org/0422/mreza.gif That's a kind of a network of connected points, which doesn't end and each point has its own number representing it. Let say the numbers are like this: 1-23-456-78910-etc. etc.. (You can't see the number 5 or 8,9... on the picture but they are there and their position is obvious, the point in middle of 4 and 6 is 5 and so on). 1 is connected to 2 and 3, 2 is connected to 1,3,5 and 4 etc. The numbers 1-2-3 indicate they represent a triangle on the picture, but the numbers 1-4-6 do not because 4 is not directly connected with 6. Let's look at 2-3-4-5, that's a parallelogram (you know why), but 4-6-7-9 is NOT a parallelogram because the in this problem there's a rule which says all the sides must be equal for all the figures - triangles and parallelograms. Also there are hexagons, for ex. 4-5-7-9-13-12 is a hexagon - all sides must be equal here too. 12345 - that doesn't represent anything, so we ignore it. I think i explained the problem well. The actual problem which is given to us by using an input of numbers like above to determine if that's a triangle/parallelogram/hexagon(according to the described rules). For ex: 1 2 3 - triangle 11 13 24 26 -parallelogram 1 2 3 4 5 - nothing 11 23 13 25 - nothing 3 2 5 - triangle I was reading computational geometry in order to solve this, but i gave up quickly, nothing seems to help here. One friend told me this site so i decided to give it a try. If you have any ideas about how to solve this, please reply, you can use pseudo code or c++ whatever. Thank you very much.

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• Playing a .TS file on iOS

  - by Jonathan Grynspan

  We're working with some hardware that produces files in the .TS format, and we'd like to play them on an iOS device. (The files are internally consistent with what iOS supports--MPEG-4 video, AAC audio.) We've been investigating three options so far: Roll our own integrated HTTP Live Streaming server and serve up a faux M3U8 playlist from within the app. This... doesn't seem to want to play nice, and we've had mixed luck actually getting the .TS files to play on devices. Unwrap the MPEG-4 and AAC data from the TS file and re-wrap it as MP4. This, I'm told, is exceedingly difficult to do, and I haven't found anything useful online that could shed light on how to do it. We've got code in the pipeline to do it but it won't be ready until long after we need it. If we could do it, I could easily subclass NSURLProtocol and have it working within a matter of hours minutes. Use FFmpeg to implement option #2. FFmpeg seems like a possible solution but it isn't configured to build for iOS and I don't have the background to get it working (whereas the rest of our engineers don't have the Apple background needed.) I think #2 is our best bet, but as I don't know the ins and outs of MPEG-2 TS and MPEG-4, I don't have the ability to put it together myself. Does anybody have any insight into this problem? Perhaps some experience playing local TS files on iOS, or some tips on converting from TS to MP4?

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• Javascript and webshop tracking/affiliate across websites, how to do?

  - by H4mm3rHead

  Hi, I have a small front end to a webshop. All customers that go through my website and buy an item from the webshop I get back 5% of the amount. I need to find a way af tracking the customers i forward from my webshop to the other webshop. And then get the webshop to reply to me when the purchase has been made. In my webshop i have made a small page: collect.aspx that requests and saves the values passed in the querystring, something like this pseudo code: string orderid = Request["orderid"]; string amount = Request["amount"]; ..save to database On the webshop i forward customers to i get to insert a javascript on the last page in the purchase flow. I have tried a lot of things but it seems that the only thing that works is to fool the browser into thinking im referring a javascript, like this: <script type="text/javascript" src="http://domain.com/mypage.aspx?orderid=4&amount=45/> I saw how other trackers did their bit, and this seems to be the general way of doing it. With this script however, i get all the orders, i only want to log those that belong tome, those who entered through my website. Here is my big problem, how to do this? I added a cookie when the user opens my page, and i want to check for this cookie again when the purchase page make the callback. It weems that i cant get the cookie from the browser when it makes the "" call. This is really buggin me now. Could anyone please tell me how this is generally done, this tracking. And what am i missing in regards to this cookie thing? All ideas on how to do this is very welcome.

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• Internet Radio Station for University

  - by ryan

  I am trying to help my University Student Radio station rethink the setup of the way they stream music, but I have some questions regarding the use of Ubuntu to stream music. Currently, the radio station uses two windows machines: one of which is used to stream the radio station and serve the website, and the other is used by rotating djs to select songs and create playlists. The computer used by djs feeds mono into the sound card of the server and the server streams the feed online. -Ideally I would like to maintain a two-computer setup: One computer as server, and another that is used to select and play music by rotating djs. -I would like to use Ubuntu for the server. -I would like to use Windows for the other machine. -The server should be able to stream song information. First, is there a way to somehow get the song information from an analog feed? Second, what is the best streaming server for radio? I have encountered shoutcast, icecast, and darwin, but I don't know where to begin in attempting to gauge them. Finally, if anyone has any tips or pointers about small internet radio station management/ setup they would be appreciated as this is my first radio station, and I am eager to hear of past experiences.

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• How to get SQL Function run a different query and return value from either query?

  - by RoguePlanetoid

  I need a function, but cannot seem to get it quite right, I have looked at examples here and elsewhere and cannot seem to get this just right, I need an optional item to be included in my query, I have this query (which works): SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title AND Manufacturer = @Manufacturer ORDER BY LenDesc DESC This works within a Function, however the Manufacturer is Optional for this search - which is to find the description of a similar item, if none is present, the other query is: SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title ORDER BY LenDesc DESC Which is missing the Manufacturer, how to I get my function to use either query based on the Manufacturer Value being present or not. The reason is I will have a function which first checks an SKU for a Description, if it is not present - it uses this method to get a Description from a Similar Product, then updates the product being added with the similar product's description. Here is the function so far: ALTER FUNCTION [dbo].[GetDescriptionByTitleManufacturer] ( @Title varchar(400), @Manufacturer varchar(160) ) RETURNS TABLE AS RETURN ( SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title AND Manufacturer = @Manufacturer ORDER BY LenDesc DESC ) I've tried adding BEGINs and IF...ELSEs but get errors or syntax problems each way I try it, I want to be able to do something like this pseudo-function (which does not work): ALTER FUNCTION [dbo].[GetDescriptionByTitleManufacturer] ( @Title varchar(400), @Manufacturer varchar(160) ) RETURNS TABLE AS BEGIN IF (@Manufacturer = Null) RETURN ( SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title ORDER BY LenDesc DESC ) ELSE RETURN ( SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title AND Manufacturer = @Manufacturer ORDER BY LenDesc DESC ) END

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• When *not* to use prepared statements?

  - by Ben Blank

  I'm re-engineering a PHP-driven web site which uses a minimal database. The original version used "pseudo-prepared-statements" (PHP functions which did quoting and parameter replacement) to prevent injection attacks and to separate database logic from page logic. It seemed natural to replace these ad-hoc functions with an object which uses PDO and real prepared statements, but after doing my reading on them, I'm not so sure. PDO still seems like a great idea, but one of the primary selling points of prepared statements is being able to reuse them… which I never will. Here's my setup: The statements are all trivially simple. Most are in the form SELECT foo,bar FROM baz WHERE quux = ? ORDER BY bar LIMIT 1. The most complex statement in the lot is simply three such selects joined together with UNION ALLs. Each page hit executes at most one statement and executes it only once. I'm in a hosted environment and therefore leery of slamming their servers by doing any "stress tests" personally. Given that using prepared statements will, at minimum, double the number of database round-trips I'm making, am I better off avoiding them? Can I use PDO::MYSQL_ATTR_DIRECT_QUERY to avoid the overhead of multiple database trips while retaining the benefit of parametrization and injection defense? Or do the binary calls used by the prepared statement API perform well enough compared to executing non-prepared queries that I shouldn't worry about it? EDIT: Thanks for all the good advice, folks. This is one where I wish I could mark more than one answer as "accepted" — lots of different perspectives. Ultimately, though, I have to give rick his due… without his answer I would have blissfully gone off and done the completely Wrong Thing even after following everyone's advice. :-) Emulated prepared statements it is!

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• Authenticated WCF: Getting the Current Security Context

  - by bradhe

  I have the following scenario: I have various user's data stored in my database. This data was entered via a web app. We'd like to expose this data back to the user over a web service so that they can integrate their data with their applications. We would also like to expose some business logic over these services. As such we do not want to use OData. This is a multi-tenant application so I only want to expose their data back to them and not other users. Likewise, the business logic we expose should be relative to the authenticated user. I would like let the user use an OASIS scheme to authenticate with the web service -- WCF already allows for this out of the box as far as I understand -- or perhaps we can issue them certificates to authenticate with. That bit hasn't really been worked out yet. Here is a bit of pseudo-code of how I envision this would work within the service: function GetUsersData(id) var user := Lookup User based on Username from Auth Context var data := Get Data From Repository based on "user" return data end function For the business logic scenario I think it would look something like this: function PerformBusinessLogic(someData) var user := Lookup User based on Username from Auth Context var returnValue := Perform some logic based on supplied data return returnValue end function The hard bit here is getting the current username (or cert info in the cert scenario) that the user authenticated with! Does WCF even enable this scenario? If not would WSE3 enable this? Thanks,

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• What is the best way to translate this recursive python method into Java?

  - by Simucal

  In another question I was provided with a great answer involving generating certain sets for the Chinese Postman Problem. The answer provided was: def get_pairs(s): if not s: yield [] else: i = min(s) for j in s - set([i]): for r in get_pairs(s - set([i, j])): yield [(i, j)] + r for x in get_pairs(set([1,2,3,4,5,6])): print x This will output the desire result of: [(1, 2), (3, 4), (5, 6)] [(1, 2), (3, 5), (4, 6)] [(1, 2), (3, 6), (4, 5)] [(1, 3), (2, 4), (5, 6)] [(1, 3), (2, 5), (4, 6)] [(1, 3), (2, 6), (4, 5)] [(1, 4), (2, 3), (5, 6)] [(1, 4), (2, 5), (3, 6)] [(1, 4), (2, 6), (3, 5)] [(1, 5), (2, 3), (4, 6)] [(1, 5), (2, 4), (3, 6)] [(1, 5), (2, 6), (3, 4)] [(1, 6), (2, 3), (4, 5)] [(1, 6), (2, 4), (3, 5)] [(1, 6), (2, 5), (3, 4)] This really shows off the expressiveness of Python because this is almost exactly how I would write the pseudo-code for the algorithm. I especially like the usage of yield and and the way that sets are treated as first class citizens. However, there in lies my problem. What would be the best way to: 1.Duplicate the functionality of the yield return construct in Java? Would it instead be best to maintain a list and append my partial results to this list? How would you handle the yield keyword. 2.Handle the dealing with the sets? I know that I could probably use one of the Java collections which implements that implements the Set interface and then using things like removeAll() to give me a set difference. Is this what you would do in that case? Ultimately, I'm looking to reduce this method into as concise and straightforward way as possible in Java. I'm thinking the return type of the java version of this method will likely return a list of int arrays or something similar. How would you handle the situations above when converting this method into Java?

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• Disabling normal link behaviour on click with an if statement in Jquery?

  - by Qwibble

  I've been banging my head with this all day, trying anything and everything I can think of to no gain. I'm no Jquery guru, so am hoping someone here can help me out. What I'm trying to do in pseudo code (concept) seems practical and easy to implement, but obviously not so =D What I have is a navigation sidebar, with sub menu's within some li's, and a link at the head of each li. When a top level link is clicked, I want the jquery to check if the link has a sibling ul. If it does, the link doesn't act like a link, but slides down the sibling sub nav. If there isn't one, the link should act normally. Here's where I'm at currently, what am I doing wrong? $('ul.navigation li a').not('ul.navigation li ul li a').click(function (){ if($(this).parent().contains('ul')){ $('ul.navigation li ul').slideUp(); $(this).siblings('ul').slideDown(); return false; } else{ alert('Link Clicked') // Maybe do some more stuff in here... } }); Any ideas?

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• 4.0/WCF: Best approach for bi-idirectional message bus?

  - by TomTom

  Just a technology update, now that .NET 4.0 is out. I write an application that communicates to the server through what is basically a message bus (instead of method calls). This is based on the internal architecture of the application (which is multi threaded, passing the messages around). There are a limited number of messages to go from the client to the server, quite a lot more from the server to the client. Most of those can be handled via a separate specialized mechanism, but at the end we talk of possibly 10-100 small messages per second going from the server to the client. The client is supposed to operate under "internet conditions". THis means possibly home end users behind standard NAT devices (i.e. typical DSL routers) - a firewalled secure and thus "open" network can not be assumed. I want to have as little latency and as little overhad for the communication as possible. What is the technologally best way to handle the message bus callback? I Have no problem regularly calling to the server for message delivery if something needs to be sent... ...but what are my options to handle the messagtes from the server to the client? WsDualHttp does work how? Especially under a NAT scenario? Just as a note: polling is most likely out - the main problem here is that I would have a significant overhead OR a significant delay, both aren ot really wanted. Technically I would love some sort of streaming appraoch, where the server can write messags to a stream while he generates them and they get sent to the client as they come. Not esure this is doable with WCF, though (if not, I may acutally decide to handle the whole message part outside of WCF and just do control / login / setup / destruction via WCF).

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• SQL Server Index cost

  - by yellowstar

  I have read that one of the tradeoffs for adding table indexes in SQL Server is the increased cost of insert/update/delete queries to benefit the performance of select queries. I can conceptually understand what happens in the case of an insert because SQL Server has to write entries into each index matching the new rows, but update and delete are a little more murky to me because I can't quite wrap my head around what the database engine has to do. Let's take DELETE as an example and assume I have the following schema (pardon the pseudo-SQL) TABLE Foo col1 int ,col2 int ,col3 int ,col4 int PRIMARY KEY (col1,col2) INDEX IX_1 col3 INCLUDE col4 Now, if I issue the statement DELETE FROM Foo WHERE col1=12 AND col2 > 34 I understand what the engine must do to update the table (or clustered index if you prefer). The index is set up to make it easy to find the range of rows to be removed and do so. However, at this point it also needs to update IX_1 and the query that I gave it gives no obvious efficient way for the database engine to find the rows to update. Is it forced to do a full index scan at this point? Does the engine read the rows from the clustered index first and generate a smarter internal delete against the index? It might help me to wrap my head around this if I understood better what is going on under the hood, but I guess my real question is this. I have a database that is spending a significant amount of time in delete and I'm trying to figure out what I can do about it. When I display the execution plan for the deletion, it just shows an entry for "Clustered Index Delete" on table Foo which lists in the details section the other indices that need to be updated but I don't get any indication of the relative cost of these other indices. Are they all equal in this case? Is there some way that I can estimate the impact of removing one or more of these indices without having to actually try it?

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• Elegant Algorithm for Parsing Data Stream Into Record

  - by Matt Long

  I am interfacing with a hardware device that streams data to my app over Wifi. The data is streaming in just fine. The data contains a character header (DATA:) that indicates a new record has begun. The issues is that the data I receive doesn't necessarily fall on the header boundary, so I have to capture the data until what I've captured contains the header. Then, everything that precedes the header goes into the previous record and everything that comes after it goes into a new record. I have this working, but wondered if anyone has done this before and has a good computer-sciencey way to solve the problem. Here's what I do: Convert the NSData of the current read to an NSString Append the NSString to a placeholder string Check placeholder string for the header (DATA:). If the header is not there, just wait for the next read. If the header exists, append whatever precedes it to a previous record placeholder and hand that placeholder off to an array as a complete record that I can further parse into fields. Take whatever shows up after the header and place it in the record placeholder so that it can be appended to in the next read. Repeat steps 3 - 5. Let me know if you see any flaws with this or have a suggestion for a better way. Seems there should be some design pattern for this, but I can't think of one. Thanks.

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• ADO/SQL Server: What is the error code for "timeout expired"?

  - by Ian Boyd

  i'm trying to trap a "timeout expired" error from ADO. When a timeout happens, ADO returns: Number: 0x80040E31 (DB_E_ABORTLIMITREACHED in oledberr.h) SQLState: HYT00 NativeError: 0 The NativeError of zero makes sense, since the timeout is not a function of the database engine (i.e. SQL Server), but of ADO's internal timeout mechanism. The Number (i.e. the COM hresult) looks useful, but the definition of DB_E_ABORTLIMITREACHED in oledberr.h says: Execution stopped because a resource limit was reached. No results were returned. This error could apply to things besides "timeout expired" (some potentially server-side), such as a governor that limits: CPU usage I/O reads/writes network bandwidth and stops a query. The final useful piece is SQLState, which is a database-independent error code system. Unfortunately the only reference for SQLState error codes i can find have no mention of HYT00. What to do? What do do? Note: i can't trust 0x80040E31 (DB_E_ABORTLIMITREACHED) to mean "timeout expired", anymore than i could trust 0x80004005 (E_UNSPECIFIED_ERROR) to mean "Transaction was deadlocked on lock resources with another process and has been chosen as the deadlock victim". My pseudo-question becomes: does anyone have documentation on what the SQLState "HYT000" means? And my real question still remains: How can i specifically trap an ADO timeout expired exception thrown by ADO? Gotta love the questions where the developer is trying to "do the right thing", but nobody knows how to do the right thing. Also gotta love how googling for DB_E_ABORTLIMITREACHED and this question is #9, with MSDN nowhere to be found. Update 3 From the OLEdb ICommand.Execute reference: DB_E_ABORTLIMITREACHED Execution has been aborted because a resource limit has been reached. For example, a query timed out. No results have been returned. "For example", meaning not an exhaustive list.

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• Is my heuristic algorithm correct? (Sudoku solver)

  - by Aposperite

  First of -yes this IS a homework- but it's primarily a theoretical question rather than a practical one, I am simply asking a confirmation if I am thinking correctly or any hints if I am not. I have been asked to compile a simple Sudoku solver (on Prolog but that is not so important right now) with the only limitation being that it must utilize a heuristic function using Best-First Algorithm. The only heuristic function I have been able to come up with is explained below: 1. Select an empty cell. 1a. If there are no empty cells and there is a solution return solution. Else return No. 2. Find all possible values it can hold. %% It can't take values currently assigned to cells on the same line/column/box. 3. Set to all those values a heuristic number starting from 1. 4. Pick the value whose heuristic number is the lowest && you haven't checked yet. 4a. If there are no more values return no. 5. If a solution is not found: GoTo 1. Else Return Solution. // I am sorry for errors in this "pseudo code." If you want any clarification let me know. So am I doing this right or is there any other way around and mine is false? Thanks in advance.

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• Rate limiting a ruby file stream

  - by Matthew Savage

  I am working on a project which involves uploading flash video files to a S3 bucket from a number of geographically distributed nodes. The video files are about 2-3mb each, and we are only sending one file (per node) every ten minutes, however the bandwidth we consume needs to be rate limited to ~20k/s, as these nodes are delivering streaming media to a CDN, and due to the locations we are only able to get 512k max upload. I have been looking into the ASW-S3 gem and while it doesn't offer any kind of rate limiting I am aware that you can pass in a IO Stream. Given this I am wondering if it might be possible to create a rate-limited stream which overrides the read method, adds in the rate limiting logic (e.g. in its simplest form a call to sleep between reads) and then call out to the super of the overridden method. Another option I considered is hacking the code for Net::HTTP and putting the rate limiting into the send_request_with_body_stream method which is using a while loop, but I'm not entirely sure which would be the best option. I have attempted at extending the IO class, however that didn't work at all, simply inheriting from the class with class ThrottledIO < IO didn't do anything. Any suggestions will be greatly appreciated.

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• Generating All Permutations of Character Combinations when # of arrays and length of each array are

  - by Jay

  Hi everyone, I'm not sure how to ask my question in a succinct way, so I'll start with examples and expand from there. I am working with VBA, but I think this problem is non language specific and would only require a bright mind that can provide a pseudo code framework. Thanks in advance for the help! Example: I have 3 Character Arrays Like So: Arr_1 = [X,Y,Z] Arr_2 = [A,B] Arr_3 = [1,2,3,4] I would like to generate ALL possible permutations of the character arrays like so: XA1 XA2 XA3 XA4 XB1 XB2 XB3 XB4 YA1 YA2 . . . ZB3 ZB4 This can be easily solved using 3 while loops or for loops. My question is how do I solve for this if the # of arrays is unknown and the length of each array is unknown? So as an example with 4 character arrays: Arr_1 = [X,Y,Z] Arr_2 = [A,B] Arr_3 = [1,2,3,4] Arr_4 = [a,b] I would need to generate: XA1a XA1b XA2a XA2b XA3a XA3b XA4a XA4b . . . ZB4a ZB4b So the Generalized Example would be: Arr_1 = [...] Arr_2 = [...] Arr_3 = [...] . . . Arr_x = [...] Is there a way to structure a function that will generate an unknown number of loops and loop through the length of each array to generate the permutations? Or maybe there's a better way to think about the problem? Thanks Everyone!

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• Rails named_scope across multiple tables

  - by wakiki

  I'm trying to tidy up my code by using named_scopes in Rails 2.3.x but where I'm struggling with the has_many :through associations. I'm wondering if I'm putting the scopes in the wrong place... Here's some pseudo code below. The problem is that the :accepted named scope is replicated twice... I could of course call :accepted something different but these are the statuses on the table and it seems wrong to call them something different. Can anyone shed light on whether I'm doing the following correctly or not? I know Rails 3 is out but it's still in beta and it's a big project I'm doing so I can't use it in production yet. class Person < ActiveRecord::Base has_many :connections has_many :contacts, :through => :connections named_scope :accepted, :conditions => ["connections.status = ?", Connection::ACCEPTED] # the :accepted named_scope is duplicated named_scope :accepted, :conditions => ["memberships.status = ?", Membership::ACCEPTED] end class Group < ActiveRecord::Base has_many :memberships has_many :members, :through => :memberships end class Connection < ActiveRecord::Base belongs_to :person belongs_to :contact, :class_name => "Person", :foreign_key => "contact_id" end class Membership < ActiveRecord::Base belongs_to :person belongs_to :group end I'm trying to run something like person.contacts.accepted and group.members.accepted which are two different things. Shouldn't the named_scopes be in the Membership and Connection classes? One solution is to just call the two different named scope something different in the Person class or even to create separate associations (ie. has_many :accepted_members and has_many :accepted_contacts) but it seems hackish and in reality I have many more than just accepted (ie. banned members, ignored connections, pending, requested etc etc)

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• Random Pairings that don't Repeat

  - by Andrew Robinson

  This little project / problem came out of left field for me. Hoping someone can help me here. I have some rough ideas but I am sure (or at least I hope) a simple, fairly efficient solution exists. Thanks in advance.... pseudo code is fine. I generally work in .NET / C# if that sheds any light on your solution. Given: A pool of n individuals that will be meeting on a regular basis. I need to form pairs that have not previously meet. The pool of individuals will slowly change over time. For the purposes of pairing, (A & B) and (B & A) constitute the same pair. The history of previous pairings is maintained. For the purpose of the problem, assume an even number of individuals. For each meeting (collection of pairs) and individual will only pair up once. Is there an algorithm that will allow us to form these pairs? Ideally something better than just ordering the pairs in a random order, generating pairings and then checking against the history of previous pairings. In general, randomness within the pairing is ok.

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• Cache consistency & spawning a thread

  - by Dave Keck

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

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• searching for a programming platform with hot code swap

  - by Andreas

  I'm currently brainstorming over the idea how to upgrade a program while it is running. (Not while debugging, a "production" system.) But one thing that is required for it, is to actually submit the changed source code or compiled byte code into the running process. Pseudo Code var method = typeof(MyClass).GetMethod("Method1"); var content = //get it from a database (bytecode or source code) SELECT content FROM methods WHERE id=? AND version=? method.SetContent(content); At first, I want to achieve the system to work without the complexity of object-orientation. That leads to the following requirements: change source code or byte code of function drop functions add new functions change the signature of a function With .NET (and others) I could inject a class via an IoC and could thus change the source code. But the loading would be cumbersome, because everything has to be in an Assembly or created via Emit. Maybe with Java this would be easier? The whole ClassLoader is replacable, I think. With JavaScript I could achieve many of the goals. Simply eval a new function (MyMethod_V25) and assign it to MyClass.prototype.MyMethod. I think one can also drop functions somehow with "del" Which general-purpose platform can handle such things?

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• Database design for a media server containing movies, music, tv and everything in between?

  - by user364114

  In the near future I am attempting to design a media server as a personal project. MY first consideration to get the project underway is architecture, it will certainly be web based but more specifically than that I am looking for suggestions on the database design. So far I am considering something like the following, where I am using [] to represent a table, the first text is the table name to give an idea of purpose and the items within {} would be fields of the table. Also not, fid is functional id referencing some other table. [Item {id, value/name, description, link, type}] - this could be any entity, single song or whole music album, game, movie - almost see this as a recursive relation, ie. a song is an item but an album that song is part of is also an item or for example a tv season is an item, with multiple items being tv episodes [Type {id, fid, mime type, etc}] - file type specific information - could identify how code handles streaming/sending this item to a user [Location {id, fid, path to file?}] [Users {id, username, email, password, ...? }] - user account information [UAC {id, fid, acess level}] - i almost feel its more flexible to seperate access control permissions form the user accounts themselves [ItemLog {id, fid, fid2, timestamp}] - fid for user id, and fid2 for item id - this way we know what user access what when [UserLog {id, fid, timestamp}] -both are logs for access, whether login or last item access [Quota {id, fid, cap}] - some sort of way to throttle users from queing up the entire site and letting it download ... Suggestions or comments are welcome as the hope is that this project will be a open source project once some code is laid out.

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• loops and conditionals inside triggers

  - by Ying

  I have this piece of logic I would like to implement as a trigger, but I have no idea how to do it! I want to create a trigger that, when a row is deleted, it checks to see if the value of one of its columns exists in another table, and if it does, it should also perform a delete on another table based on another column. So say we had a table Foo that has columns Bar, Baz. This is what id be doing if i did not use a trigger: function deleteFromFooTable(FooId) { SELECT (Bar,Baz) FROM FooTable WHERE id=FooId if not-empty(SELECT * FROM BazTable WHERE id=BazId) DELETE FROM BarTable WHERE id=BarId DELETE FROM FooTable WHERE id=FooId } I jumped some hoops in that pseudo code, but i hope you all get where im going. It seems what i would need is a way to do conditionals and to loop(in case of multiple row deletes?) in the trigger statement. So far, I haven't been able to find anything. Is this not possible, or is this bad practice? Thanks!

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• New TabItem Content ActualHeight crashes Xaml Window

  - by Jack Navarro

  I am able to create new TabItems with Content dynamically to a new window by streaming the Xaml with XamlReader: NewWindow newWindow = new NewWindow(); newWindow.Show(); TabControl myTabCntrol = newWindow.FindName("GBtabControl") as TabControl; StringReader stringReader = new StringReader(XamlGrid); XmlReader xmlReader = XmlReader.Create(stringReader); TabItem myTabItem = new TabItem(); myTabItem.Header = qDealName; myTabItem.Content = (UIElement)XamlReader.Load(xmlReader); myTabCntrol.Items.Add(myTabItem); This works fine. It displays a new grid wrapped in a scrollviewer. The problem is access the TabItem content from the newWindow. TabItem ti = GBtabControl.SelectedItem as TabItem; string scrollvwnm = "scrollViewer" + ti.Header.ToString(); MessageBox.Show(ti.ActualHeight.ToString()); // returns 21.5 ScrollViewer scrlvwr = this.FindName(scrollvwnm) as ScrollViewer; MessageBox.Show(scrollvwnm); // Displays name double checked for accuracy MessageBox.Show(scrlvwr.ActualHeight.ToString()); //Crashes ScrollViewer scrlvwr = ti.FindName(scrollvwnm) as ScrollViewer; MessageBox.Show(scrollvwnm); // Displays name double checked for accuracy MessageBox.Show(scrlvwr.ActualHeight.ToString()); //Also Crashes Is there a method to refresh UI in XAML so the new window is able to access the newly loaded tab item content? Thanks

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• What are the benefits of the PHP the different PHP compression libraries?

  - by Christopher W. Allen-Poole

  I've been looking into ways to compress PHP libraries, and I've found several libraries which might be useful, but I really don't know much about them. I've specifically been reading about bcompiler and PHAR libraries. Is there any performance benefit in either of these? Are there any "gotchas" I need to watch out for? What are the relative benefits? Do either of them add to/detract from performance? I'm also interested in learning of other libs which might be out there which are not obvious in the documentation? As an aside, does anyone happen to know whether these work more like zip files which just happen to have the code in there, or if they operate more like Python's pre-compiling which actually runs a pseudo-compiler? ======================= EDIT ======================= I've been asked, "What are you trying to accomplish?" Well, I suppose the answer is that this is all hypothetical. It is a combination of these: What if my pet project becomes the most popular web project on earth and I want to distribute it quickly and easily? (hay, a man can dream, right?) It also seems if using PHAR can be done easily, it would be the best way to create a subversion snapshot. Python has this really cool pre-compiling policy, I wonder if PHP has something like that? These libraries seem to do something similar. Will they do that? Hey, these libraries seem pretty neat, but I'd like clarification on the differences as they seem to do the same thing

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• JQuery Deferred - Adding to the Deferred contract

  - by MgSam

  I'm trying to add another asynchronous call to the contract of an existing Deferred before its state is set to success. Rather than try and explain this in English, see the following pseudo-code: $.when( $.ajax({ url: someUrl, data: data, async: true, success: function (data, textStatus, jqXhr) { console.log('Call 1 done.') jqXhr.pipe( $.ajax({ url: someUrl, data: data, async: true, success: function (data, textStatus, jqXhr) { console.log('Call 2 done.'); }, }) ); }, }), $.ajax({ url: someUrl, data: data, async: true, success: function (data, textStatus, jqXhr) { console.log('Call 3 done.'); }, }) ).then(function(){ console.log('All done!'); }); Basically, Call 2 is dependent on the results of Call 1. I want Call 1 and Call 3 to be executed in parallel. Once all 3 calls are complete, I want the All Done code to execute. My understanding is that Deferred.pipe() is supposed to chain another asynchronous call to the given deferred, but in practice, I always get Call 2 completing after All Done. Does anyone know how to get jQuery's Deferred to do what I want? Hopefully the solution doesn't involve ripping the code apart into chunks any further. Thanks for any help.

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