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  • Java: Making concurrent MySQL queries from multiple clients synchronised

    - by Misha Gale
    I work at a gaming cybercafe, and we've got a system here (smartlaunch) which keeps track of game licenses. I've written a program which interfaces with this system (actually, with it's backend MySQL database). The program is meant to be run on a client PC and (1) query the database to select an unused license from the pool available, then (2) mark this license as in use by the client PC. The problem is, I've got a concurrency bug. The program is meant to be launched simultaneously on multiple machines, and when this happens, some machines often try and acquire the same license. I think that this is because steps (1) and (2) are not synchronised, i.e. one program determines that license #5 is available and selects it, but before it can mark #5 as in use another copy of the program on another PC tries to grab that same license. I've tried to solve this problem by using transactions and table locking, but it doesn't seem to make any difference - Am I doing this right? Here follows the code in question: public LicenseKey Acquire() throws SmartLaunchException, SQLException { Connection conn = SmartLaunchDB.getConnection(); int PCID = SmartLaunchDB.getCurrentPCID(); conn.createStatement().execute("LOCK TABLE `licensekeys` WRITE"); String sql = "SELECT * FROM `licensekeys` WHERE `InUseByPC` = 0 AND LicenseSetupID = ? ORDER BY `ID` DESC LIMIT 1"; PreparedStatement statement = conn.prepareStatement(sql); statement.setInt(1, this.id); ResultSet results = statement.executeQuery(); if (results.next()) { int licenseID = results.getInt("ID"); sql = "UPDATE `licensekeys` SET `InUseByPC` = ? WHERE `ID` = ?"; statement = conn.prepareStatement(sql); statement.setInt(1, PCID); statement.setInt(2, licenseID); statement.executeUpdate(); statement.close(); conn.commit(); conn.createStatement().execute("UNLOCK TABLES"); return new LicenseKey(results.getInt("ID"), this, results.getString("LicenseKey"), results.getInt("LicenseKeyType")); } else { throw new SmartLaunchException("All licenses of type " + this.name + "are in use"); } }

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  • Program crashes after trying to use a recently created file. C#

    - by Jason T.
    So here is my code if (!File.Exists(pathName)) { File.Create(pathName); } StreamWriter outputFile = new StreamWriter(pathName,true); But whenever I run the program the first time the path with file gets created. However once I get to the StreamWriter line my program crashes because it says my fie is in use by another process. Is there something I'm missing between the File.Create and the StreamWriter statements?

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  • How to write my own global lock / unlock functions for PostgreSQL

    - by rafalmag
    I have postgresql (in perlu) function getTravelTime(integer, timestamp), which tries to select data for specified ID and timestamp. If there are no data or if data is old, it downloads them from external server (downloading time ~300ms). Multiple process use this database and this function. There is an error when two process do not find data and download them and try to do an insert to travel_time table (id and timestamp pair have to be unique). I thought about locks. Locking whole table would block all processes and allow only one to proceed. I need to lock only on id and timestamp. pg_advisory_lock seems to lock only in "current session". But my processes uses their own sessions. I tried to write my own lock/unlock functions. Am I doing it right? I use active waiting, how can I omit this? Maybe there is a way to use pg_advisory_lock() as global lock? My code: CREATE TABLE travel_time_locks ( id_key integer NOT NULL, time_key timestamp without time zone NOT NULL, UNIQUE (id_key, time_key) ); ------------ -- Function: mylock(integer, timestamp) DROP FUNCTION IF EXISTS mylock(integer, timestamp) CASCADE; -- Usage: SELECT mylock(1, '2010-03-28T19:45'); -- function tries to do a global lock similar to pg_advisory_lock(key, key) CREATE OR REPLACE FUNCTION mylock(id_input integer, time_input timestamp) RETURNS void AS $BODY$ DECLARE rows int; BEGIN LOOP BEGIN -- active waiting here !!!! :( INSERT INTO travel_time_locks (id_key, time_key) VALUES (id_input, time_input); EXCEPTION WHEN unique_violation THEN CONTINUE; END; EXIT; END LOOP; END; $BODY$ LANGUAGE 'plpgsql' VOLATILE COST 1; ------------ -- Function: myunlock(integer, timestamp) DROP FUNCTION IF EXISTS myunlock(integer, timestamp) CASCADE; -- Usage: SELECT myunlock(1, '2010-03-28T19:45'); -- function tries to do a global unlock similar to pg_advisory_unlock(key, key) CREATE OR REPLACE FUNCTION myunlock(id_input integer, time_input timestamp) RETURNS integer AS $BODY$ DECLARE BEGIN DELETE FROM ONLY travel_time_locks WHERE id_key=id_input AND time_key=time_input; RETURN 1; END; $BODY$ LANGUAGE 'plpgsql' VOLATILE COST 1;

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  • Develop a custom file sync provider over file transfer WCF service

    - by user336622
    Hi All I'm trying to develop a custom sync provider to sync files over the internet using WCF service. We already have a file transfer service and it's working in production but I need to implement a custom sync provider on top of it. I've checked the solution in Braynt Likes blog here but this doesn't fulfill my needs. Any advices, guidance, or sample code to help is really appreciated?

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  • Extract a portion of a Qt .ui file into its own .ui file

    - by Grant Limberg
    We have a designer creating a user interface for an application. The main window has several QStackedWidgets used for in place panel switching. What I'd like to be able to do is extract each individual panel that makes up each page of the QStackedWidget into it its own .ui file. Is there an easy way to accomplish this from within Qt Designer, or are there any other tools to help accomplish this task short of redesigning all of the panels in their own .ui files?

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  • Writing Strings to files in python

    - by Leif Andersen
    I'm getting the following error when trying to write a string to a file in pythion: Traceback (most recent call last): File "export_off.py", line 264, in execute save_off(self.properties.path, context) File "export_off.py", line 244, in save_off primary.write(file) File "export_off.py", line 181, in write variable.write(file) File "export_off.py", line 118, in write file.write(self.value) TypeError: must be bytes or buffer, not str I basically have a string class, which contains a string: class _off_str(object): __slots__ = 'value' def __init__(self, val=""): self.value=val def get_size(self): return SZ_SHORT def write(self,file): file.write(self.value) def __str__(self): return str(self.value) Furthermore, I'm calling that class like this: def write(self, file): for variable in self.variables: variable.write(file) I have no idea what is going on. I've seen other python programs writing strings to files, so why can't this one? Thank you very much for your help.

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  • SSIS Technique to Remove/Skip Trailer and/or Bad Data Row in a Flat File

    - by Compudicted
    I noticed that the question on how to skip or bypass a trailer record or a badly formatted/empty row in a SSIS package keeps coming back on the MSDN SSIS Forum. I tried to figure out the reason why and after an extensive search inside the forum and outside it on the entire Web (using several search engines) I indeed found that it seems even thought there is a number of posts and articles on the topic none of them are employing the simplest and the most efficient technique. When I say efficient I mean the shortest time to solution for the fellow developers. OK, enough talk. Let’s face the problem: Typically a flat file (e.g. a comma delimited/CSV) needs to be processed (loaded into a database in most cases really). Oftentimes, such an input file is produced by some sort of an out of control, 3-rd party solution and would come in with some garbage characters and/or even malformed/miss-formatted rows. One such example could be this imaginary file: As you can see several rows have no data and there is an occasional garbage character (1, in this example on row #7). Our task is to produce a clean file that will only capture the meaningful data rows. As an aside, our output/target may be a database table, but for the purpose of this exercise we will simply re-format the source. Let’s outline our course of action to start off: Will use SSIS 2005 to create a DFT; The DFT will use a Flat File Source to our input [bad] flat file; We will use a Conditional Split to process the bad input file; and finally Dump the resulting data to a new [clean] file. Well, only four steps, let’s see if it is too much of work. 1: Start the BIDS and add a DFT to the Control Flow designer (I named it Process Dirty File DFT): 2, and 3: I had added the data viewer to just see what I am getting, alas, surprisingly the data issues were not seen it:   What really is the key in the approach it is to properly set the Conditional Split Transformation. Visually it is: and specifically its SSIS Expression LEN([After CS Column 0]) > 1 The point is to employ the right Boolean expression (yes, the Conditional Split accepts only Boolean conditions). For the sake of this post I re-named the Output Name “No Empty Rows”, but by default it will be named Case 1 (remember to drag your first column into the expression area)! You can close your Conditional Split now. The next part will be crucial – consuming the output of our Conditional Split. Last step - #4: Add a Flat File Destination or any other one you need. Click on the Conditional Split and choose the green arrow to drop onto the target. When you do so make sure you choose the No Empty Rows output and NOT the Conditional Split Default Output. Make the necessary mappings. At this point your package must look like: As the last step will run our package to examine the produced output file. F5: and… it looks great!

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  • A deadlock was detected while trying to lock variables in SSIS

    Error: 0xC001405C at SQL Log Status: A deadlock was detected while trying to lock variables "User::RowCount" for read/write access. A lock cannot be acquired after 16 attempts. The locks timed out. Have you ever considered variable locking when building your SSIS packages? I expect many people haven’t just because most of the time you never see an error like the one above. I’ll try and explain a few key concepts about variable locking and hopefully you never will see that error. First of all, what is all this variable locking all about? Put simply SSIS variables have to be locked before they can be accessed, and then of course unlocked once you have finished with them. This is baked into SSIS, presumably to reduce the risk of race conditions, but with that comes some additional overhead in that you need to be careful to avoid lock conflicts in some scenarios. The most obvious place you will come across any hint of locking (no pun intended) is the Script Task or Script Component with their ReadOnlyVariables and ReadWriteVariables properties. These two properties allow you to enter lists of variables to be used within the task, or to put it another way, these lists of variables to be locked, so that they are available within the task. During the task pre-execute phase the variables and locked, you then use them during the execute phase when you code is run, and then unlocked for you during the post-execute phase. So by entering the variable names in one of the two list, the locking is taken care of for you, and you just read and write to the Dts.Variables collection that is exposed in the task for the purpose. As you can see in the image above, the variable PackageInt is specified, which means when I write the code inside that task I don’t have to worry about locking at all, as shown below. public void Main() { // Set the variable value to something new Dts.Variables["PackageInt"].Value = 199; // Raise an event so we can play in the event handler bool fireAgain = true; Dts.Events.FireInformation(0, "Script Task Code", "This is the script task raising an event.", null, 0, ref fireAgain); Dts.TaskResult = (int)ScriptResults.Success; } As you can see as well as accessing the variable, hassle free, I also raise an event. Now consider a scenario where I have an event hander as well as shown below. Now what if my event handler uses tries to use the same variable as well? Well obviously for the point of this post, it fails with the error quoted previously. The reason why is clearly illustrated if you consider the following sequence of events. Package execution starts Script Task in Control Flow starts Script Task in Control Flow locks the PackageInt variable as specified in the ReadWriteVariables property Script Task in Control Flow executes script, and the On Information event is raised The On Information event handler starts Script Task in On Information event handler starts Script Task in On Information event handler attempts to lock the PackageInt variable (for either read or write it doesn’t matter), but will fail because the variable is already locked. The problem is caused by the event handler task trying to use a variable that is already locked by the task in Control Flow. Events are always raised synchronously, therefore the task in Control Flow that is raising the event will not regain control until the event handler has completed, so we really do have un-resolvable locking conflict, better known as a deadlock. In this scenario we can easily resolve the problem by managing the variable locking explicitly in code, so no need to specify anything for the ReadOnlyVariables and ReadWriteVariables properties. public void Main() { // Set the variable value to something new, with explicit lock control Variables lockedVariables = null; Dts.VariableDispenser.LockOneForWrite("PackageInt", ref lockedVariables); lockedVariables["PackageInt"].Value = 199; lockedVariables.Unlock(); // Raise an event so we can play in the event handler bool fireAgain = true; Dts.Events.FireInformation(0, "Script Task Code", "This is the script task raising an event.", null, 0, ref fireAgain); Dts.TaskResult = (int)ScriptResults.Success; } Now the package will execute successfully because the variable lock has already been released by the time the event is raised, so no conflict occurs. For those of you with a SQL Engine background this should all sound strangely familiar, and boils down to getting in and out as fast as you can to reduce the risk of lock contention, be that SQL pages or SSIS variables. Unfortunately we cannot always manage the locking ourselves. The Execute SQL Task is very often used in conjunction with variables, either to pass in parameter values or get results out. Either way the task will manage the locking for you, and will fail when it cannot lock the variables it requires. The scenario outlined above is clear cut deadlock scenario, both parties are waiting on each other, so it is un-resolvable. The mechanism used within SSIS isn’t actually that clever, and whilst the message says it is a deadlock, it really just means it tried a few times, and then gave up. The last part of the error message is actually the most accurate in terms of the failure, A lock cannot be acquired after 16 attempts. The locks timed out.  Now this may come across as a recommendation to always manage locking manually in the Script Task or Script Component yourself, but I think that would be an overreaction. It is more of a reminder to be aware that in high concurrency scenarios, especially when sharing variables across multiple objects, locking is important design consideration. Update – Make sure you don’t try and use explicit locking as well as leaving the variable names in the ReadOnlyVariables and ReadWriteVariables lock lists otherwise you’ll get the deadlock error, you cannot lock a variable twice!

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  • sort surname in alphabet from file to file JAVA

    - by user577939
    hello all. I need some help. I have wrote this code and dont now how to sort surnames in alphabet from my file to other file. import java.io.; import java.util.; class Asmuo { String pavarde; String vardas; long buvLaikas; int atv1; int atv2; int atv3; } class Irasas { Asmuo duom; Irasas kitas; } class Sarasas { private Irasas p; Sarasas() { p = null; } Irasas itrauktiElementa(String pv, String v, long laikas, int d0, int d1, int d2) { String pvrd, vrd; int data0; int data1; int data2; long lks; lks = laikas; pvrd = pv; vrd = v; data0 = d0; data1 = d1; data2 = d2; Irasas r = new Irasas(); r.duom = new Asmuo(); uzpildymasDuomenimis(r, pvrd, vrd, lks, d0, d1, d2); r.kitas = p; p = r; return r; } void uzpildymasDuomenimis(Irasas r, String pv, String v, long laik, int d0, int d1, int d2) { r.duom.pavarde = pv; r.duom.vardas = v; r.duom.atv1 = d0; r.duom.buvLaikas = laik; r.duom.atv2 = d1; r.duom.atv3 = d2; } void spausdinti() { Irasas d = p; int i = 0; try { FileWriter fstream = new FileWriter("rez.txt"); BufferedWriter rez = new BufferedWriter(fstream); while (d != null) { System.out.println(d.duom.pavarde + " " + d.duom.vardas + " " + d.duom.buvLaikas + " " + d.duom.atv1 + " " + d.duom.atv2 + " " + d.duom.atv3); rez.write(d.duom.pavarde + " " + d.duom.vardas + " " + d.duom.buvLaikas + " " + d.duom.atv1 + " " + d.duom.atv2 + " " + d.duom.atv3 + "\n"); d = d.kitas; i++; } rez.close(); } catch (Exception e) { System.err.println("Error: " + e.getMessage()); } } } public class Gyventojai { public static void main(String args[]) { Sarasas sar = new Sarasas(); Calendar atv = Calendar.getInstance(); Calendar isv = Calendar.getInstance(); try { FileInputStream fstream = new FileInputStream("duom.txt"); DataInputStream in = new DataInputStream(fstream); BufferedReader br = new BufferedReader(new InputStreamReader(in)); String eil; while ((eil = br.readLine()) != null) { String[] cells = eil.split(" "); String pvrd = cells[0]; String vrd = cells[1]; atv.set(Integer.parseInt(cells[2]), Integer.parseInt(cells[3]), Integer.parseInt(cells[4])); isv.set(Integer.parseInt(cells[5]), Integer.parseInt(cells[6]), Integer.parseInt(cells[7])); long laik = (isv.getTimeInMillis() - atv.getTimeInMillis()) / (24 * 60 * 60 * 1000); int d0 = Integer.parseInt(cells[2]); int d1 = Integer.parseInt(cells[3]); int d2 = Integer.parseInt(cells[4]); sar.itrauktiElementa(pvrd, vrd, laik, d0, d1, d2); } in.close(); } catch (Exception e) { System.err.println("Error: " + e.getMessage()); } sar.spausdinti(); } }

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  • File Segmentation when trying to write in a file

    - by user1286390
    I am trying in C language to use the method of bisection to find the roots of some equation, however when I try to write every step of this process in a file I get the problem "Segmentation fault". This might be an idiot fault that I did, however I have been trying to solve this for a long time. I am compiling using gcc and that is the code: #include <stdio.h> #include <stdlib.h> #include <math.h> #define R 1.0 #define h 1.0 double function(double a); void attractor(double *a1, double *a2, double *epsilon); void attractor(double *a1, double *a2, double *epsilon) { FILE* bisection; double a2_copia, a3, fa1, fa2; bisection = fopen("bisection-part1.txt", "w"); fa1 = function(*a1); fa2 = function(*a2); if(function(*a1) - function(*a2) > 0.0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); fprintf(bisection, "a1 a2 fa1 fa2 epsilon\n"); a2_copia = 0.0; if(function(*a1) * function(*a2) < 0.0 && *epsilon >= 0.00001) { a3 = *a2 - (*a2 - *a1); a2_copia = *a2; *a2 = a3; if(function(*a1) - function(*a2) > 0.0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); if(function(*a1) * function(*a2) < 0.0 && *epsilon >= 0.00001) { fprintf(bisection, "%.4f %.4f %.4f %.4f %.4f\n", *a1, *a2, function(*a1), function(*a1), *epsilon); attractor(a1, a2, epsilon); } else { *a2 = a2_copia; *a1 = a3; if(function(*a1) - function(*a2) > 0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); if(function(*a1) * function(*a2) < 0.0 && *epsilon >= 0.00001) { fprintf(bisection, "%.4f %.4f %.4f %.4f %.4f\n", *a1, *a2, function(*a1), function(*a1), *epsilon); attractor(a1, a2, epsilon); } } } fa1 = function(*a1); fa2 = function(*a2); if(function(*a1) - function(*a2) > 0.0) *epsilon = function(*a1) - function(*a2); else *epsilon = function(*a2) - function(*a1); fprintf(bisection, "%.4f %.4f %.4f %.4f %.4f\n", a1, a2, fa1, fa2, epsilon); } double function(double a) { double fa; fa = (a * cosh(h / (2 * a))) - R; return fa; } int main() { double a1, a2, fa1, fa2, epsilon; a1 = 0.1; a2 = 0.5; fa1 = function(a1); fa2 = function(a2); if(fa1 - fa2 > 0.0) epsilon = fa1 - fa2; else epsilon = fa2 - fa1; if(epsilon >= 0.00001) { fa1 = function(a1); fa2 = function(a2); attractor(&a1, &a2, &epsilon); fa1 = function(a1); fa2 = function(a2); if(fa1 - fa2 > 0.0) epsilon = fa1 - fa2; else epsilon = fa2 - fa1; } if(epsilon < 0.0001) printf("Vanish at %f", a2); else printf("ERROR"); return 0; } Thanks anyway and sorry if this question is not suitable.

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  • Fixing corrupt files or corrupt file table on a USB drive?

    - by Kelsey
    I was doing a virus scan on an external USB drive while copying data over to it. While AVG was scanning my system got locked up I think due to the USB drive running out of space and it required a reboot. Since that time all data on the external drive is no longer accessible. I can see all the files in the root and directories but I cannot browse into any of them as Windows 7 gives an error stating they are corrupt. I think the file table or whatever it uses to store the index of what exists on the drive has been corrupted since it still shows the the drive as being almost full but everything I do a properties check on says it is 0 bytes. Does anyone know how to 'unlock' or recover this data? Is there a way to rebuild the file table somehow? Luckily I can recover this data from other sources as a last resort but I would like to fix this if possible. Any help would be appreciated. Thanks.

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  • Why Does DreamWeaver CS5 Discriminate between File Extensions, Even After Modding Mime Types!?

    - by Sam
    Hi folks, Even After I forced DreamWeaver CS5 to allow opening of .ast extensions as a MIME type of php5, which DreamWeaver now opens and colors correctly as described here, I still have trouble figuring out why it still discriminates between the two file extensions! Symptoms: External Files & Design View I have a file foo.php which php includes other files (e.g. the php-combined css.php and js.php). Now, when opening foo.php all functions work perfectly: the external (included) php files are all recognised correctly. However, when I change foo.php foo.ast, and open it again, It does not recognise the files extensions anymore in the top bar. Also, I lose the Design / Live View functionality.** When I change foo.ast to foo.php, all works again! Anyone any clues of why there remains a a difference between one and other extension? Note1: I have added the .ast extension to these four files, next to .php: 1 C:\Users\Sam\AppData\Local\VirtualStore\Program Files (x86)\Adobe\Adobe Dreamweaver CS5\configuration\DocumentTypes\MMDocumentTypes.xml 2 C:\Program Files (x86)\Adobe\Adobe Dreamweaver CS5\configuration\DocumentTypes\MMDocumentTypes.xml 3 C:\Users\Sam\AppData\Roaming\Adobe\Dreamweaver CS5\en_US\Configuration\Extensions.txt 4 C:\Program Files (x86)\Adobe\Adobe Dreamweaver CS5\configuration\Extensions.txt Note2: sometimes, even .php files do not want to show in design view or live view. Could this be caused by a corrupted installation?

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  • Is there a POSIX pathname that can't name a file?

    - by Charles Stewart
    Are there any legal paths in POSIX that cannot be associated with a file, regular or irregular? That is, for which test -e "$LEGITIMATEPOSIXPATHNAME" cannot succeed? Clarification #1: pathnames By "legal paths in POSIX", I mean ones that POSIX says are allowed, not ones that POSIX doesn't explicitly forbid. I've looked this up, and the are POSIX specification calls them character strings that: Use only characters from the portable filename character set [a-zA-Z0-9._-] (cf. http://www.opengroup.org/onlinepubs/009695399/basedefs/xbd_chap03.html#tag_03_276); Do not begin with -; and Have length between 1 and NAME_MAX, a number unspecified for POSIX that is not less than 14. POSIX also allows that filesystems will probably be more relaxed than this, but it forbids the characters NUL and / from appearing in filenames. Note that such a paradigmatically UNIX filename as lost+found isn't FPF, according to this def. There's another constant PATH_MAX, whose use needs no further explanation. The ideal answer will use FPFs, but I'm interested in any example with filenames that POSIX doesn't expressly forbid. Clarification #2: impossibility Obviously, pathnames normally could be bound to a file. But UNIX semantics will tell you that there are special places that couldn't normally have arbitrary files created, like in the /dev directory. Are any such special places stipulated in POSIX? That is what the question is getting after.

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  • Everyone can access my Windows 7 Homegroup file shares - Even Windows XP computers.

    - by adriangrigore
    Hi, I have 3 computers in my network, two running Windows 7 and one running Windows XP. I've set up a homegroup on both Windows 7 computers. Also, all computers are in the same Workgroup. The problem is that one of the Windows 7 computers makes all shares accessible to the entire Workgroup instead of just sharing to the Homegroup as it should be. I created the file share in Windows 7 via right-click in the explorer, then click on "Share For" - "Homegroup (Read/Write)" (translated from German, so the actual wording may be different). Also, when I look at the file sharing properties of that folder, Windows Explorer informs me that Users must have a valid account and password for this Computer to access drive shares. Unfortunately this is not true. Being in the same Workgroup is enough to get access. Homegroup restrictions work as expected on my other Windows 7 computer. When trying to browse those shares from the XP computer, I get a dialog asking for a login and password. What might cause homegroup restrictions to fail and how can I fix this?

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  • which is best smart automatic file replication solution for cloud storage based systems.

    - by TORr0t
    I am looking for a solution for a project i am working on. We are developing a websystem where people can upload their files and other people can download it. (similar to rapidshare.com model) Problem is, some files can be demanded much more than other files. The scenerio is like: I have uploaded my birthday video and shared it with all of my friend, I have uploaded it to myproject.com and it was stored in one of the cluster which has 100mbit connection. Problem is, once all of my friends want to download the file, they cant download it since the bottleneck here is 100mbit which is 15MB per second, but i got 1000 friends and they can only download 15KB per second. I am not taking into account that the hdd is serving same files. My network infrastrucre is as follows: 1 gbit server(client) and connected to 4 Nodes of storage servers that have 100mbit connection. 1gbit server can handle the 1000 users traffic if one of storage node can stream more than 15MB per second to my 1gbit (client) server and visitor will stream directly from client server instead of storage nodes. I can do it by replicating the file into 2 nodes. But i dont want to replicate all files uploadded to my network since it is costing much more. So i need a cloud based system, which will push the files into replicated nodes automatically when demanded to those files are high, and when the demand is low, they will delete from other nodes and it will stay in only 1 node. I have looked to gluster and asked in their irc channel that, gluster cant do such a thing. It is only able to replicate all the files or none of the files. But i need it the cluster software to do it automatically. Any solutions ? (instead of recommending me amazon s3) S

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  • What's a good solution for file-tagging in linux?

    - by julien
    I've been looking for a way to tag my files and search/filter them based on those tags. Here are my (updated) requirements : any file readable by the user can be tagged freely a user can search for files matching one or several tags files can be moved around without losing the previously associated tags the system could be backed up easily no dependencies on any desktop environment if any gui is involved, there must be a cli fallback I've been hoping for some basic filesystem & coreutils hackery to handle this, but I haven' thought about this hard enough yet. Meanwhile I'll review beagle and metatracker, which have been mentionned here, and see how they perform. Ok so beagle has huge gnome dependencies, and tracker is okish, but still has some dependencies I don't like... Been doing some more research, and the way to go could very well be extended file attributes. That's a native solution for most recent filesystems, but they aren't very well supported yet (most coreutils destroys them by default, cp for example needs the -a flag to preserve them). Would like to hear some thoughts on using them while I try my hand at some hacks myself, eventhough this might warrant a new question.

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  • Does anybody know of existing code to read a mork file (Thunderbird Address Book)?

    - by bruceatk
    I have the need to read the Thunderbird address book on the fly. It is stored in a file format called Mork. Not a pleasant file format to read. I found a 1999 article explaining the file format. I would love to know if someone already has gone through this process and could make the code available. I found mork.pl by Jamie Zawinski (he worked on Netscape Navigator), but I was hoping for a .NET solution. I'm hoping StackOverflow will come to the rescue, because this just seems like a waste of my time to write something to read this file format when it should be so simple. I love the comments that Jamie put in his perl script. Here is my favorite part: # Let me make it clear that McCusker is a complete barking lunatic. # This is just about the stupidest file format I've ever seen.

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  • replace file with hardlink to another file atomically

    - by Ben Clifford
    I have two directory entries, a and b. Before, a and b point to different inodes. Afterwards, I want b to point to the same inode as a does. I want this to be safe - by which I mean if I fail somewhere, b either points to its original inode or the a inode. most especially I don't want to end up with b disappearing. mv is atomic when overwriting. ln appears to not work when the destination already exists. so it looks like i can say: ln a tmp mv tmp b which in case of failure will leave a 'tmp' file around, which is undesirable but not a disaster. Is there a better way to do this? (what I'm actually trying to do is replace files that have identical content with a single inode containing that content, shared between all directory entries)

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  • Regex to match the first file in a rar archive file set in Python

    - by mridang
    I need to uncompress all the files in a directory and for this I need to find the first file in the set. I'm currently doing this using a bunch of if statements and loops. Can i do this this using regex? Here's a list of files that i need to match: yes.rar yes.part1.rar yes.part01.rar yes.part001.rar yes.r01 yes.r001 These should NOT be matched: no.part2.rar no.part02.rar no.part002.rar no.part011.rar no.r002 no.r02 I found a similar regex on this thread but it seems that Python doesn't support varible length lookarounds. A single line regex would be complicated but I'll document it well and it's not a problem. It's just one of those problems you beat your heap up, over. Thanks in advance guys. :)

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  • Parse HTML file to grab all ID and Classes for a CSS file

    - by iamfriendly
    Hey all, A short while ago, I'm fairly certain I came across an application (or perhaps a plugin for Coda - the IDE I use) which quickly parses a html document and then spits out all of the elements with IDs and Classes for me to use in a CSS file. Having fully 'got into' zen coding - using the wonderful TEA plugin for Coda, I'm now hot on the heels of this app/plugin again. I've tried and failed miserably at hunting through Google, but have come up completely empty handed. Does anyone know of anything which can do this? Happy New Year everyone!

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  • How get file names using OpenFileDialog in .NET (1000+ file multiselect)

    - by Cole
    Maybe some of you have come across this before.... I am opening files for parsing. I'm using OpenFileDialog, of course, but i'm limited to a buffer of 2048 on the .FileNames string. Thus, I can only select a few hundred files. This is OK for most cases. However, fore example, I have in one case 1400 files to open. Do you know a way to do this with the open file dialog. I just want the string array of .FileNames, I pass that to parser class. I was also thinking of offering a FolderBrowserDialog option and then I'd use some other method to just loop through all the files in a directory, like the DirectoryInfo class. I'd do this as a last resort if I can't have an all in one solution.

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  • Replace string in one file with contents of a second file

    - by jag7720
    I have two files: fileA: date >> /root/kvno.out kvno serverXXX\$ >> /root/kvno.out fileB: foobar I need to create a new file, fileC, with the same contents as fileA, except with the string XXX being replaced with the contents of fileB: date >> /root/kvno.out kvno serverfoobar\$ >> /root/kvno.out I'd like to do this using sed. I tried some of the examples I found but I only get the contents of fileB in fileC.

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