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  • Why should I install Python packages into `~/.local`?

    - by Matthew Rankin
    Background I don't develop using OS X's system provided Python versions (on OS X 10.6 that's Python 2.5.4 and 2.6.1). I don't install anything in the site-packages directory for the OS provided versions of Python. (The only exception is Mercurial installed from a binary package, which installs two packages in the Python 2.6.1 site-packages directory.) I installed three versions of Python, all using the Mac OS X installer disk image: Python 2.6.6 Python 2.7 Python 3.1.2 I don't like polluting the site-packages directory for my Python installations. So I only install the following five base packages in the site-packages directory. For the actual method/commands used to install these, see SO Question 4324558. setuptools/ez_setup distribute pip virtualenv virtualenvwrapper All other packages are installed in virtualenvs. I am the only user of this MacBook. Questions Given the above background, why should I install the five base packages in ~/.local? Since I'm installing these base packages into the site-packages directories of Python distributions that I've installed, I'm isolated from the OS X's Python distributions. Using this method, should I be concerned about Glyph's comment that other things could potentially break (see his comment below)? Again, I'm only interested in where to install those five base packages. Related Questions/Info I'm asking because of Glyph's comment to my answer to SO question 4314376, which stated: NO. NEVER EVER do sudo python setup.py install whatever. Write a ~/.pydistutils.cfg that puts your pip installation into ~/.local or something. Especially files named ez_setup.py tend to suck down newer versions of things like setuptools and easy_install, which can potentially break other things on your operating system. Previously, I asked What's the proper way to install pip, virtualenv, and distribute for Python?. However, no one answered the "why" of using ~/.local.

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  • Java Socket Closes After Connection?

    - by Matthew
    Why does this port/socket close once a connection has been made by a client? package app; import java.io.*; import java.net.*; public class socketServer { public static void main(String[] args) { int port = 3333; boolean socketBindedToPort = false; try { ServerSocket ServerSocketPort = new ServerSocket(port); System.out.println("SocketServer Set Up on Port: " + port); socketBindedToPort = true; if(socketBindedToPort == true) { Socket clientSocket = null; try { clientSocket = ServerSocketPort.accept();//This method blocks until a socket connection has been made to this port. System.out.println("Waiting for client connection on port:" + port); /** THE CLIENT HAS MADE A CONNECTION **/ System.out.println("CLIENT IS CONENCTED"); } catch (IOException e) { System.out.println("Accept failed: " + port); System.exit(-1); } } else { System.out.println("Socket did not bind to the port:" + port); } } catch(IOException e) { System.out.println("Could not listen on port: " + port); System.exit(-1); } } }

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  • c# .net MVC4 Model to represent table or form

    - by Matthew Chambers
    Hello I am a little confused with regards to models in mvc 4 and thought someone may be able to point me in the right direction. This would be most appreciated. For example if i have a table that has the following fields [StringLength(100, ErrorMessage = "The {0} must be at least {2} characters long.", MinimumLength = 5)] public string UserName { get; set; } [Required(ErrorMessage="Email Address is Required")] [StringLength(15, ErrorMessage = "Email Address must be between {0} and {1} in size",MinimumLength = 5 )] [DataType(DataType.EmailAddress)] [Display(Name="Email")] public string Email { get; set; } [MaxLength(25)] [Display(Name="Mobile Telephone Number")] public string Mobile {get;set;} [MaxLength(500)] [Display(Name="Headline")] public string Headline {get;set;} [Required] [StringLength(200)] [Display(Name = "First Name")] public string FirstName {get;set;} [Required] [StringLength(200)] [Display(Name="Surname")] public string Surname { get; set;} public virtual int? DayOfBirthId { get; set; } public virtual DayOfBirth DayOfBirth { get; set; } public virtual int? MonthOfBirthId { get; set; } public virtual MonthOfBirth MonthOfBirth { get; set; } public virtual int? YearOfBirthId { get; set; } public virtual YearOfBirth YearOfBirth{get;set;} This is my user profile table in the database. However I would like a form that the user registers to the site with. When they first register i do not need all the details such as telephone all i really need is there username, email address and password. Do i create another model for this. Or do i have one model and on the controller set the fields to null or empty string that are not required on registration. I have validation also so would this be set for data that has not been entered on the form. My question is ultimately should all forms represent models- should the database be redesigned to meet this required. Or should the controller set the values that are not required. Or should there be another model that represents the form be created which maps to this table. I am a little confused on this and clarification of anyone would be most appreciated.

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  • [JAVA] Activity Stream- Producing X amount of objects in a panel on app load

    - by Matthew De'Loughry
    Hi guys, Just wondering if you could help wanting to produce an activity stream in Java, the idea was to have a JLabel and text area followed by a divider be displayed on a screen and then repeated X amount of times according to what data was in a database. What I was wondering is how could I possibly repeat the placing the jlabel, text area, and diveder on the screen above the last rendered objects on the fly and all displayed correctly no matter the size of the text area of each set of object sort of like the image below. Hope I made it clear as I could thanks

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  • Why is the page still caching even after the no-cache headers have been sent?

    - by Matthew Grasinger
    I've done a ton of research on this and have asked many people with help and still no success. Here are the details... I'm involved in developing a website that pulls data from various data files, combines them in a temp .csv file, and then is graphed using a popular graphing library: dygraphs. The bulk of the website is written in PHP. The parameters that determine the data that is graphed are stored in the users session, the .csv is named after the users session and available for download, and then the .csv file is written in a script that passes it to the dygraphs object. And we've found, even with the no-cache headers sent: header("Cache-Control: no-cache, must-revalidate"); header("Expires: Sat, 26 Jul 1997 05:00:00 GMT"); Many users experience in the middle of a session, (if enough different graphs are generated) the page displaying an older, static rendering of the page (data they had graphed earlier in the session) as if it were cached and loaded instead of getting a new request. It only gets weirder though: I've checked using developer tools in both Firefox and Chrome and both browsers are receiving the no-cache headers just fine; Even when the problem occurs if you view the page source, the source is the correct content (a table/legend is also dynamically created using php, the source shows the correct table, but what is rendered is older content); the page begins to render correctly until the graph is about to be display, and then shows the older content; the older content displays as if it were a completely static overlay--the cached graph does not have the same dynamic features (roll over data point display, zoom and pan, etc.) And it is as if the correct page were somewhere beneath it (the download button for the csv file moves depending on how large the table is. The older, static page does nothing if you click the download .csv button, but if you can manage to find the one in the page beneath it you can click and still download the .csv. The data in the .csv is correct) It is one of the strangest things I've seen in development thus far. Some other relevant facts are that all the problems I've personally experience occurred while I was using Chrome. Non of these symptoms have been reported by Firefox users. IE users have had the same problems (IE users are forced to use chrome frame). I'm at my wits end at this point. We've sent the php headers; we've tried setting the cache profile for php on IIS as "DisableCache" (or whatever); we've tried sending a random query string to the results page; we've tried all the appropriate meta tags--all with no success.

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  • Iterators over a LInked List in a Game in Java

    - by Matthew
    I am using OpenGl in android and they have a callback method called draw that gets called with out my control. (As fast as the device can handle if I am not mistaken) I have a list of "GameObjects" that have a .draw method and a .update method. I have two different threads that handle each of those. So, the question is, can I declare two different iterators in two different methods in two different threads that iterate over the same Linked List? If so, do I simply declare ListIterator<GameObject> l = objets.listIterator() each time I want a new iterator and it won't interfere with other iterators?

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  • Multi-key dictionaries (of another kind) in C#?

    - by Matthew Scharley
    Building on this question, is there a simple solution for having a multi-key dictionary where either key individually can be used to identify the value? ie. MultikeyDictionary<TKey1, TKey2, TValue> foo; foo.Add(key1, key2, value); myValue = foo[key1]; // value == myValue foo.Remove(key2); myValue = foo[key1]; // invalid, Exception or null returned

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  • Steps for MySQL DB Replication

    - by Manish Agrawal
    Following are the steps for MySQL Replication implementation on Linux machine: Pre-implementation steps for DB Replication:   1.    Identify the databases to be replicated 2.    Identify the tables to be ignored during replication per database for example log tables 3.  Carefully identify and replace the variables and paths(locations) mentioned (in bold) in the commands given below with appropriate values 4.  Schedule the maintenance activity in odd hours as these activities will affect all the databases on Master database server       Implementation steps for DB Replication:     1.    Configure the /etc/my.cnf file on Master database server to enable Binary logging, setting of server id and configuring of dbnames for which logging should be done. [mysqld] log-bin=mysql-bin server-id=1 binlog-do-db = dbname   Note: You can specify multiple DB in binlog-do-db by using comma separated dbname values like: dbname1, dbname2, …, dbnameN   2.    On Master database, Grant Replication Slave Privileges, by executing following command on mysql prompt mysql> GRANT REPLICATION SLAVE ON *.* TO slaveuser@<hostname> identified by ‘slavepassword’;   3.    Stop the Master & Slave database by giving the command      mysqladmin shutdown   4.    Start the Master database by giving the command      /usr/local/mysql-5.0.22/bin/mysqld_safe --user=user&     5.    mysql> FLUSH TABLES WITH READ LOCK; Note: Leave the client (putty session) from which you issued the FLUSH TABLES statement running, so that the read lock remains in effect. If you exit the client, the lock is released. 6.    mysql > SHOW MASTER STATUS;          +---------------+----------+--------------+------------------+          | File          | Position | Binlog_Do_DB | Binlog_Ignore_DB |          +---------------+----------+--------------+------------------+          | mysql-bin.003 | 117       | dbname       |                  |          +---------------+----------+--------------+------------------+ Note: Note this information as this will be required while starting of Slave and replication in later steps   7.    Take MySQL dump by giving the following command, In another session window (putty window) run the following command: mysqldump –u user --ignore-table=dbname.tbl_name -–ignore-table=dbname.tbl_name2 --master-data dbname > dbname_dump.db Note: When choosing databases to include in the dump, remember that you will need to filter out databases on each slave that you do not want to include in the replication process.     8.    Unlock the tables on Master by giving following command: mysql> UNLOCK TABLES;   9.    Copy the dump file to Slave DB server   10.  Startup the Slave by using option --skip-slave      /usr/local/mysql-5.0.22/bin/mysqld_safe --user=user --skip-slave&   11.  Restore the dump file on Slave DB server      mysql –u user dbname < dbname_dump.db   12.  Stop the Slave database by giving the command      mysqladmin shutdown   13.  Configure the /etc/my.cnf file on the Slave database server [mysqld] server-id=2 replicate-ignore-table = dbname.tablename   14.  Start the Slave Mysql Server with 'replicate-do-db=DB name' option.      /usr/local/mysql-5.0.22/bin/mysqld_safe --user=user --replicate-do-db=dbname --skip-slave   15.  Configure the settings at Slave server for Master host name, log filename and position within the log file as shown in Step 6 above Use Change Master statement in the MySQL session mysql> CHANGE MASTER TO MASTER_HOST='<master_host_name>', MASTER_USER='<replication_user_name>', MASTER_PASSWORD='<replication_password>', MASTER_LOG_FILE='<recorded_log_file_name>', MASTER_LOG_POS=<recorded_log_position>;   16.  On Slave Servers mysql prompt give the following command: a.     mysql > START SLAVE; b.    mysql > SHOW SLAVE STATUS;         Note: To stop slave for backup or any other activity you can use the following command on the Slave Servers mysql prompt: mysql> STOP SLAVE     Refer following links for more information on MySQL DB Replication: http://dev.mysql.com/doc/refman/5.0/en/replication-options.html http://crazytoon.com/2008/04/21/mysql-replication-replicate-by-choice/ http://dev.mysql.com/doc/refman/5.0/en/mysqldump.html

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  • Uploadify with ruby on rails 'bad content body' 500 Internal Server Error

    - by Mr_Nizzle
    I'm Getting this error in my development log while uploadify is uploading the file and in the view i get an 'IO ERROR' beside filename. /!\ FAILSAFE /!\ Thu Mar 18 11:54:53 -0500 2010 Status: 500 Internal Server Error bad content body /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/utils.rb:351:in `parse_multipart' /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/utils.rb:323:in `loop' /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/utils.rb:323:in `parse_multipart' /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/request.rb:133:in `POST' /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/methodoverride.rb:15:in `call' /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.3/lib/action_controller/params_parser.rb:15:in `call' /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.3/lib/action_controller/session/cookie_store.rb:93:in `call' /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.3/lib/action_controller/reloader.rb:29:in `call' /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.3/lib/action_controller/failsafe.rb:26:in `call' /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in `call' /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in `synchronize' /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in `call' /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.3/lib/action_controller/dispatcher.rb:106:in `call' /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/content_length.rb:13:in `call' /usr/lib/ruby/gems/1.8/gems/rack-1.0.1/lib/rack/handler/fastcgi.rb:58:in `serve' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:103:in `process_request' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:153:in `with_signal_handler' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:101:in `process_request' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:78:in `process_each_request' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:77:in `each' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:77:in `process_each_request' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:76:in `catch' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:76:in `process_each_request' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:51:in `process!' /usr/lib/ruby/gems/1.8/gems/rails-2.3.3/lib/fcgi_handler.rb:23:in `process!' dispatch.fcgi:24 any idea on this?

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  • c# Named Pipe Asynchronous Peeking

    - by KJ Tsanaktsidis
    Hey all, I need to find a way to be notified when a System.IO.Pipe.NamedPipeServerStream opened in asynchronous mode has more data available for reading on it- a WaitHandle would be ideal. I cannot simply use BeginRead() to obtain such a handle because it's possible that i might be signaled by another thread which wants to write to the pipe- so I have to release the lock on the pipe and wait for the write to be complete, and NamedPipeServerStream doesnt have a CancelAsync method. I also tried calling BeginRead(), then calling the win32 function CancelIO on the pipe if the thread gets signaled, but I don't think this is an ideal solution because if CancelIO is called just as data is arriving and being processed, it will be dropped- I still wish to keep this data, but process it at a later time, after the write. I suspect the win32 function PeekNamedPipe might be useful but i'd like to avoid having to continuously poll for new data with it. In the likley event that the above text is a bit unclear, here's roughly what i'd like to be able to do... NamedPipeServerStream pipe; ManualResetEvent WriteFlag; //initialise pipe lock (pipe) { //I wish this method existed WaitHandle NewDataHandle = pipe.GetDataAvailableWaithandle(); Waithandle[] BreakConditions = new Waithandle[2]; BreakConditions[0] = NewDataHandle; BreakConditions[1] = WriteFlag; int breakcode = WaitHandle.WaitAny(BreakConditions); switch (breakcode) { case 0: //do a read on the pipe break; case 1: //break so that we release the lock on the pipe break; } }

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  • quartz throws deadlocks under load

    - by Khandelwal
    We are using Quartz with Spring and our configuration is throwing deadlocks when quartz has more than 1 thread configured. I'm starting to believe that it's because we don't have our quartz configured correctly with Spring, but I can't find enough documentation on how to configure the two to play nicely. We are running on both Windows and Linux environments - pointing at MSSQL and Oracle DBs. With both OS, using either DB, we can throw the following deadlock errors... We're consistently throwing these deadlock errors. We run under heavy load, inserting hundreds of quartz triggers in a matter of minutes. 2010-03-17 18:52:31,737 [] [] ERROR [DFScheduler_Worker-42] core.ErrorLogger core.ErrorLogger (QuartzScheduler.java:2185) - An error occured while marking executed job complete. job= 'BPM.6e41a6567f0000020100362a51dc7a50' org.quartz.JobPersistenceException: Couldn't remove trigger: Transaction (Process ID 87) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. [See nested exception: com.microsoft.sqlserver.jdbc.SQLServerException: Transaction (Process ID 87) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction.] at org.quartz.impl.jdbcjobstore.JobStoreSupport.removeTrigger(JobStoreSupport.java:1469)at org.quartz.impl.jdbcjobstore.JobStoreSupport.triggeredJobComplete(JobStoreSupport.java:2978)at org.quartz.impl.jdbcjobstore.JobStoreSupport$39.execute(JobStoreSupport.java:2962) at org.quartz.impl.jdbcjobstore.JobStoreSupport$41.execute(JobStoreSupport.java:3713)at org.quartz.impl.jdbcjobstore.JobStoreSupport.executeInNonManagedTXLock(JobStoreSupport.java:3747) at org.quartz.impl.jdbcjobstore.JobStoreSupport.executeInNonManagedTXLock(JobStoreSupport.java:3709)at org.quartz.impl.jdbcjobstore.JobStoreSupport.triggeredJobComplete(JobStoreSupport.java:2958)at org.quartz.core.QuartzScheduler.notifyJobStoreJobComplete(QuartzScheduler.java:1727)at org.quartz.core.JobRunShell.run(JobRunShell.java:273) at org.quartz.simpl.SimpleThreadPool$WorkerThread.run(SimpleThreadPool.java:534) Caused by: com.microsoft.sqlserver.jdbc.SQLServerException: Transaction (Process ID 87) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(Unknown Source at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(Unknown Source) at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.doExecutePreparedStatement(Unknown Source) at ... org.quartz.impl.jdbcjobstore.StdJDBCDelegate.deleteSimpleTrigger(StdJDBCDelegate.java:1820) at org.quartz.impl.jdbcjobstore.JobStoreSupport.deleteTriggerAndChildren(JobStoreSupport.java:1345 at org.quartz.impl.jdbcjobstore.JobStoreSupport.removeTrigger(JobStoreSupport.java:1453 ... 9 more

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  • Cannot use READPAST in snapshot isolation mode

    - by Marcus
    I have a process which is called from multiple threads which does the following: Start transaction Select unit of work from work table with by finding the next row where IsProcessed=0 with hints (UPDLOCK, HOLDLOCK, READPAST) Process the unit of work (C# and SQL stored procedures) Commit the transaction The idea of this is that a thread dips into the pool for the "next" piece of work, and processes it, and the locks are there to ensure that a single piece of work is not processed twice. (the order doesn't matter). All this has been working fine for months. Until today that is, when I happened to realise that despite enabling snapshot isolation and making it the default at the database level, the actual transaction creation code was manually setting an isolation level of "ReadCommitted". I duly changed that to "Snapshot", and of course immediately received the "You can only specify the READPAST lock in the READ COMMITTED or REPEATABLE READ" error message. Oops! The main reason for locking the row was to "mark the row" in such a way that the "mark" would be removed when the transaction that applied the mark was committed and the lock seemed to be the best way to do this, since this table isn't read otherwise except by these threads. If I were to use the IsProcessed flag as the lock, then presumably I would need to do the update first, and then select the row I just updated, but I would need to employ the NOLOCK flag to know whether any other thread had set the flag on a row. All sounds a bit messy. The easiest option would be to abandon the snapshot isolation mode altogether, but the design of step #3 requires it. Any bright ideas on the best way to resolve this problem? Thanks Marcus

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  • Java FileLock for Reading and Writing

    - by bobtheowl2
    I have a process that will be called rather frequently from cron to read a file that has certain move related commands in it. My process needs to read and write to this data file - and keep it locked to prevent other processes from touching it during this time. A completely separate process can be executed by a user to (potential) write/append to this same data file. I want these two processes to play nice and only access the file one at a time. The nio FileLock seemed to be what I needed (short of writing my own semaphore type files), but I'm having trouble locking it for reading. I can lock and write just fine, but when attempting to create lock when reading I get a NonWritableChannelException. Is it even possible to lock a file for reading? Seems like a RandomAccessFile is closer to what I need, but I don't see how to implement that. Here is the code that fails: FileInputStream fin = new FileInputStream(f); FileLock fl = fin.getChannel().tryLock(); if(fl != null) { System.out.println("Locked File"); BufferedReader in = new BufferedReader(new InputStreamReader(fin)); System.out.println(in.readLine()); ... The exception is thrown on the FileLock line. java.nio.channels.NonWritableChannelException at sun.nio.ch.FileChannelImpl.tryLock(Unknown Source) at java.nio.channels.FileChannel.tryLock(Unknown Source) at Mover.run(Mover.java:74) at java.lang.Thread.run(Unknown Source) Looking at the JavaDocs, it says Unchecked exception thrown when an attempt is made to write to a channel that was not originally opened for writing. But I don't necessarily need to write to it. When I try creating a FileOutpuStream, etc. for writing purposes it is happy until I try to open a FileInputStream on the same file.

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  • Svn import with auto-props & pre-commit hook

    - by James Tisato
    My company's svn repo has a lot of MS Word docs in it. We've implemented a policy that all .doc files must have the svn:needs-lock property set to prevent parallel access on files that are hard to merge (we've also done this for xls, ppt, pdf etc.). We've implemented the policy by distributing a svn config with auto-props set appropriately for all relevant document types. We've also set up a pre-commit hook that checks that all added files of these types have the needs-lock property set (i.e. if they forget/are too lazy to update their svn config file, they won't be able to add any docs to the repo). The problem I'm having, however, is that the pre-commit hook fails when users try to import files into the repo, e.g. some users like to add files directly thru TortoiseSVN's Repo Browser, which effectively is an svn import. Through testing on other file types, I have seen that doing an import does in fact apply the auto-props listed in my config, but they don't seem to be applied at the point that the pre-commit hook runs. When importing .doc files, the hook fails, saying that the needs-lock property is missing. Is there really much difference between adding a single file to a working copy and committing it vs importing a file directly? Do we need to tailor our precommit hook in some way to cater for this scenario?

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  • Java Concurrency : Synchronized(this) => and this.wait() and this.notify()

    - by jens
    Hello Experts, I would appreciate your help in understand a "Concurrency Example" from: http://forums.sun.com/thread.jspa?threadID=735386 Qute Start: public synchronized void enqueue(T obj) { // do addition to internal list and then... this.notify(); } public synchronized T dequeue() { while (this.size()==0) { this.wait(); } return // something from the queue } Quote End: My Question is: Why is this code valid? = When I synchronize a method like "public synchronized" = then I synchronize on the "Instance of the Object == this". However in the example above: Calling "dequeue" I will get the "lock/monitor" on this Now I am in the dequeue method. As the list is zero, the calling thread will be "waited" From my understanding I have now a deadlock situation, as I will have no chance of ever enquing an object (from an nother thread), as the "dequeue" method is not yet finised and the dequeue "method" holds the lock on this: So I will never ever get the possibility to call "enequeue" as I will not get the "this" lock. Backround: I have exactly the same problem: I have some kind of connection pool (List of Connections) and need to block if all connections are checked. What is the correct way to synchronize the List to block, if size exceeds a limit or is zero? Thank you very much Jens

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  • XmlHttpRequest in a bookmarklet returns empty responseText on GET?

    - by David Eyk
    I'm trying to build a javascript bookmarklet for a special URL shortening service we've built at http://esv.to for shortening scripture references (i.e. "Matthew 5" becomes "http://esv.to/Mt5". The bookmarklet is supposed to do a GET request to http://api.esv.to/Matthew+5, which returns a text/plain response of http://esv.to/Mt5. The code for the bookmarklet itself looks like this (expanded for readability): var body = document.getElementsByTagName('body')[0], script = document.createElement('script'); script.type = 'text/javascript'; script.src = 'http://esv.to/media/js/bookmarklet.js'; body.appendChild(script); void(0); The code from http://esv.to/media/js/bookmarklet.js looks like this: (function() { function shorten(ref, callback) { var url = "http://esv.to/api/" + escape(ref); var req = new XMLHttpRequest(); req.onreadystatechange = function shortenIt() { if ( this.readyState == 4 && this.status == 200 ) { callback(req.responseText); }; }; req.open( "GET", url ); req.send(); }; function doBookmarklet() { var ref = prompt("Enter a scripture reference or keyword search to link to:", "") shorten(ref, function (short) { prompt("Here is your shortened ESV URL:", short); }); }; doBookmarklet(); })(); When called from http://esv.to itself, the bookmarklet works correctly. But when used on another page, it does not. The strange thing is, when I watch the request from Firebug, the response is 200 OK, the browser downloads 17 bytes (the length of the returned string), but the response body is empty! No error is thrown, just an empty responseText on the XmlHttpRequest object. Now, according to http://stackoverflow.com/questions/664689/ajax-call-from-bookmarklet, GET shouldn't violate the same origin policy. Is this a bug? Is there a workaround?

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  • In .NET when Aborting Thread, can this piece of code get corrupted?

    - by bosko
    Little intro: In complex multithreaded aplication (enterprise service bus EBS), I need to use Thread.Abort, because this EBS accepts user written modules which communicates with hardware security modules. So if this module gets deadlocked or hardware stops responding - i need to just unload this module and rest of this server aplication must keep runnnig. So there is abort sync mechanism which ensures that code can be aborted only in user section and this section must be marked as AbortAble. If this happen there is possibility that ThreadAbortException will be thrown in this pieace of code: public void StopAbortSection() { var id = Thread.CurrentThread.ManagedThreadId; lock (threadIdMap[id]) { .... } } If module is on AbortSection and Aplication decides to abort module, but after this decision but before actual Thread.Abort, module enters NonAbortableSection by calling this method, but lock is actualy taken on that locking object. So lock will block until Abort or abort can be executed before reaching this block by this code. But Object with this method is essential and i need to be sure that this pieace of code is safe to abort in any moment. Probably i have to mention that threadIdMap is Dictionary(int,ManualResetEvent), so locking object is instance of ManualResetEvent. I hope you now understad my question. Sorry for its largeness.

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  • SQL Concurrent test update question

    - by ptoinson
    Howdy Folks, I have a SQLServer 2008 database in which I have a table for Tags. A tag is just an id and a name. The definition of the tags table looks like: CREATE TABLE [dbo].[Tag]( [ID] [int] IDENTITY(1,1) NOT NULL, [Name] [varchar](255) NOT NULL CONSTRAINT [PK_Tag] PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ) Name is also a unique index. further I have several processes adding data to this table at a pretty rapid rate. These processes use a stored proc that looks like: ALTER PROC [dbo].[lg_Tag_Insert] @Name varchar(255) AS DECLARE @ID int SET @ID = (select ID from Tag where Name=@Name ) if @ID is null begin INSERT Tag(Name) VALUES (@Name) RETURN SCOPE_IDENTITY() end else begin return @ID end My issues is that, other than being a novice at concurrent database design, there seems to be a race condition that is causing me to occasionally get an error that I'm trying to enter duplicate keys (Name) into the DB. The error is: Cannot insert duplicate key row in object 'dbo.Tag' with unique index 'IX_Tag_Name'. This makes sense, I'm just not sure how to fix this. If it where code I would know how to lock the right areas. SQLServer is quite a different beast. First question is what is the proper way to code this 'check, then update pattern'? It seems I need to get an exclusive lock on the row during the check, rather than a shared lock, but it's not clear to me the best way to do that. Any help in the right direction will be greatly appreciated. Thanks in advance.

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  • How to program critical section for reader-writer systems?

    - by Srinivas Nayak
    Hi, Lets say, I have a reader-writer system where reader and writer are concurrently running. 'a' and 'b' are two shared variables, which are related to each other, so modification to them needs to be an atomic operation. A reader-writer system can be of the following types: rr ww r-w r-ww rr-w rr-ww where [ r : single reader rr: multiple reader w : single writer ww: multiple writer ] Now, We can have a read method for a reader and a write method for a writer as follows. I have written them system type wise. rr read_method { read a; read b; } ww write_method { lock(m); write a; write b; unlock(m); } r-w r-ww rr-w rr-ww read_method { lock(m); read a; read b; unlock(m); } write_method { lock(m); write a; write b; unlock(m); } For multiple reader system, shared variable access doesn't need to be atomic. For multiple writer system, shared variable access need to be atomic, so locked with 'm'. But, for system types 3 to 6, is my read_method and write_method correct? How can I improve? Sincerely, Srinivas Nayak

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  • Delete throws "deleted object would be re-saved by cascade"

    - by Greg
    I have following model: <class name="Person" table="Person" optimistic-lock="version"> <id name="Id" type="Int32" unsaved-value="0"> <generator class="native" /> </id> <!-- plus some properties here --> </class> <class name="Event" table="Event" optimistic-lock="version"> <id name="Id" type="Int32" unsaved-value="0"> <generator class="native" /> </id> <!-- plus some properties here --> </class> <class name="PersonEventRegistration" table="PersonEventRegistration" optimistic-lock="version"> <id name="Id" type="Int32" unsaved-value="0"> <generator class="native" /> </id> <property name="IsComplete" type="Boolean" not-null="true" /> <property name="RegistrationDate" type="DateTime" not-null="true" /> <many-to-one name="Person" class="Person" column="PersonId" foreign-key="FK_PersonEvent_PersonId" cascade="all-delete-orphan" /> <many-to-one name="Event" class="Event" column="EventId" foreign-key="FK_PersonEvent_EventId" cascade="all-delete-orphan" /> </class> There are no properties pointing to PersonEventRegistration either in Person nor in Event. When I try to delete an entry from PersonEventRegistration, I get the following error: "deleted object would be re-saved by cascade" The problem is, I don't store this object in any other collection - the delete code looks like this: public bool UnregisterFromEvent(Person person, Event entry) { var registrationEntry = this.session .CreateCriteria<PersonEventRegistration>() .Add(Restrictions.Eq("Person", person)) .Add(Restrictions.Eq("Event", entry)) .Add(Restrictions.Eq("IsComplete", false)) .UniqueResult<PersonEventRegistration>(); bool result = false; if (null != registrationEntry) { using (ITransaction tx = this.session.BeginTransaction()) { this.session.Delete(registrationEntry); tx.Commit(); result = true; } } return result; } What am I doing wrong here?

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  • Atomic int writes on file

    - by Waneck
    Hello! I'm writing an application that will have to be able to handle many concurrent accesses to it, either by threads as by processes. So no mutex'es or locks should be applied to this. To make the use of locks go down to a minimum, I'm designing for the file to be "append-only", so all data is first appended to disk, and then the address pointing to the info it has updated, is changed to refer to the new one. So I will need to implement a small lock system only to change this one int so it refers to the new address. How is the best way to do it? I was thinking about maybe putting a flag before the address, that when it's set, the readers will use a spin lock until it's released. But I'm afraid that it isn't at all atomic, is it? e.g. a reader reads the flag, and it is unset on the same time, a writer writes the flag and changes the value of the int the reader may read an inconsistent value! I'm looking for locking techniques but all I find is either for thread locking techniques, or to lock an entire file, not fields. Is it not possible to do this? How do append-only databases handle this? Thanks! Cauê

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  • Unexpected $end in PHP file

    - by mattbd
    I'm working on a PHP contact form, but I can't get it to work. I get the following error in the Apache server log, running on an Ubuntu Server VM: PHP Parse error: syntax error, unexpected $end in /home/matthew/Sites/contactFormResponse.php on line 75, referer: http://192.168.1.4/contactForm.php From googling this error, it sounds like it's normally caused by either using the short PHP tag when the server's not set up to recognise them, or by having a block of code that isn't closed correctly. But as far as I can see that isn't the case here - as far as I can see it's all closed correctly. Here's the PHP code: <?php error_reporting(E_ALL); // Define variables to hold the name, email address and message, and import the information into the variables $name = $_POST['NameInput']; $email = $_POST['EmailAddress']; $telno = $_POST['ContactNumber']; $querytype = $_POST['QueryType']; $bookingstartdate = $_POST['BookingStartDay'] . $_POST['BookingStartMonth'] . $_POST['BookingStartYear']; $bookingenddate = $_POST['BookingEndDay'] . $_POST['BookingEndMonth'] . $_POST['BookingEndYear']; $message = $_POST['QueryText']; // Validate the inputs - send it if it's OK if(3 < strlen($name) && 3 < strlen($email)) { $email_message = <<< EMAIL Message from contact form at holidaychalet.co.uk Name: $name Email: $email Contact Number: $telno Query Type: $querytype Booking Start Date: $bookingstartdate Booking End Date: $bookingenddate The message: $message EMAIL; $headers = "cc:[email protected]\r\n"; if(mail('matthew@localhost','Contact form email', $email_message, $headers)) { echo "Thanks for completing the form! I'll be in touch shortly!"; } else { echo "Something went wrong - please use the back button and try again"; } } else { echo "You didn't complete the form fully enough! Please use go back using your web browser's back button"; } ?>

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  • File Locked by Services (after service code reading the text file)

    - by rvpals
    I have a windows services written in C# .NET. The service is running on a internal timer, every time the interval hits, it will go and try to read this log file into a String. My issue is every time the log file is read, the service seem to lock the log file. The lock on that log file will continue until I stop the windows service. At the same time the service is checking the log file, the same log file needs to be continuously updated by another program. If the file lock is on, the other program could not update the log file. Here is the code I use to read the text log file. private string ReadtextFile(string filename) { string res = ""; try { System.IO.FileStream fs = new System.IO.FileStream(filename, System.IO.FileMode.Open, System.IO.FileAccess.Read); System.IO.StreamReader sr = new System.IO.StreamReader(fs); res = sr.ReadToEnd(); sr.Close(); fs.Close(); } catch (System.Exception ex) { HandleEx(ex); } return res; } Thank you.

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  • How did this happen?? Git error? Some other fluke?

    - by marfarma
    Every file in this Rails project is duplicated with a -e and again with a -e-e tacked onto the end of it, like the following. It's that way in my GitHub repository too. But I can't figure out how it happened. Any clue? Google searching comes up empty. -rw-r--r--@ 1 usrname staff 959 Jan 7 02:13 Gemfile -rw-r--r-- 1 usrname staff 958 Jan 5 01:10 Gemfile-e -rw-r--r-- 1 usrname staff 958 Jan 5 01:09 Gemfile-e-e -rw-r--r-- 1 usrname staff 6650 Jan 7 02:13 Gemfile.lock -rw-r--r-- 1 usrname staff 6650 Jan 5 01:10 Gemfile.lock-e -rw-r--r-- 1 usrname staff 6650 Jan 5 01:09 Gemfile.lock-e-e lrwxr-xr-x 1 usrname staff 18 Jan 5 00:37 README.rdoc - doc/README_FOR_APP -rw-r--r-- 1 usrname staff 283 Jan 5 01:10 Rakefile -rw-r--r-- 1 usrname staff 283 Jan 5 01:10 Rakefile-e -rw-r--r-- 1 usrname staff 283 Jan 5 01:09 Rakefile-e-e drwxr-xr-x 6 usrname staff 204 Jan 5 00:37 app drwxr-xr-x 5 usrname staff 170 Jan 5 01:10 autotest drwxr-xr-x 28 usrname staff 952 Jan 5 01:15 config -rw-r--r-- 1 usrname staff 173 Jan 5 01:10 config.ru -rw-r--r-- 1 usrname staff 173 Jan 5 01:10 config.ru-e -rw-r--r-- 1 usrname staff 173 Jan 5 01:09 config.ru-e-e

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