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  • Writing a synchronized thread-safety wrapper for NavigableMap

    - by polygenelubricants
    java.util.Collections currently provide the following utility methods for creating synchronized wrapper for various collection interfaces: synchronizedCollection(Collection<T> c) synchronizedList(List<T> list) synchronizedMap(Map<K,V> m) synchronizedSet(Set<T> s) synchronizedSortedMap(SortedMap<K,V> m) synchronizedSortedSet(SortedSet<T> s) Analogously, it also has 6 unmodifiedXXX overloads. The glaring omission here are the utility methods for NavigableMap<K,V>. It's true that it extends SortedMap, but so does SortedSet extends Set, and Set extends Collection, and Collections have dedicated utility methods for SortedSet and Set. Presumably NavigableMap is a useful abstraction, or else it wouldn't have been there in the first place, and yet there are no utility methods for it. So the questions are: Is there a specific reason why Collections doesn't provide utility methods for NavigableMap? How would you write your own synchronized wrapper for NavigableMap? Glancing at the source code for OpenJDK version of Collections.java seems to suggest that this is just a "mechanical" process Is it true that in general you can add synchronized thread-safetiness feature like this? If it's such a mechanical process, can it be automated? (Eclipse plug-in, etc) Is this code repetition necessary, or could it have been avoided by a different OOP design pattern?

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  • How can I ignore the block content reading in Perl.

    - by Nano HE
    Hello. I plan to ignore the block content which include the start line of "MaterializeU4()" with the subroutin() read_block below. But failed. # Read a constant definition block from a file handle. # void return when there is no data left in the file. # Otherwise return an array ref containing lines to in the block. sub read_block { my $fh = shift; my @lines; my $block_started = 0; while( my $line = <$fh> ) { # how to correct my code below? I don't need the 2nd block content. $block_started++ if ( ($line =~ /^(status)/) && (index($line, "MaterializeU4") != 0) ) ; if( $block_started ) { last if $line =~ /^\s*$/; push @lines, $line; } } return \@lines if @lines; return; } Data as below: __DATA__ status DynTest = <dynamic 100> vid = 10002 name = "DynTest" units = "" status VIDNAME9000 = <U4 MaterializeU4()> vid = 9000 name = "VIDNAME9000" units = "degC" status DynTest = <U1 100> vid = 100 name = "Hello" units = "" Output: <StatusVariables> <SVID logicalName="DynTest" type="L" value="100" vid="10002" name="DynTest" units=""></SVID> <SVID logicalName="VIDNAME9000" type="L" value="MaterializeU4()" vid="9000" name="VIDNAME9000" units="degC"></SVID> <SVID logicalName="DynTest" type="L" value="100" vid="100" name="Hello" units=""></SVID> </StatusVariables> [Updated] I print the value of index($line, "MaterializeU4"), it output 25. Then I updated the code as below $block_started++ if ( ($line =~ /^(status)/) && (index($line, "MaterializeU4") != 25) Now it works. Any comments are welcome about my practice. Thank you.

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  • How can I skip some block content while reading in Perl.

    - by Nano HE
    Hello. I plan to skip the block content which include the start line of "MaterializeU4()" with the subroutin() read_block below. But failed. # Read a constant definition block from a file handle. # void return when there is no data left in the file. # Otherwise return an array ref containing lines to in the block. sub read_block { my $fh = shift; my @lines; my $block_started = 0; while( my $line = <$fh> ) { # how to correct my code below? I don't need the 2nd block content. $block_started++ if ( ($line =~ /^(status)/) && (index($line, "MaterializeU4") != 0) ) ; if( $block_started ) { last if $line =~ /^\s*$/; push @lines, $line; } } return \@lines if @lines; return; } Data as below: __DATA__ status DynTest = <dynamic 100> vid = 10002 name = "DynTest" units = "" status VIDNAME9000 = <U4 MaterializeU4()> vid = 9000 name = "VIDNAME9000" units = "degC" status DynTest = <U1 100> vid = 100 name = "Hello" units = "" Output: <StatusVariables> <SVID logicalName="DynTest" type="L" value="100" vid="10002" name="DynTest" units=""></SVID> <SVID logicalName="VIDNAME9000" type="L" value="MaterializeU4()" vid="9000" name="VIDNAME9000" units="degC"></SVID> <SVID logicalName="DynTest" type="L" value="100" vid="100" name="Hello" units=""></SVID> </StatusVariables> [Updated] I print the value of index($line, "MaterializeU4"), it output 25. Then I updated the code as below $block_started++ if ( ($line =~ /^(status)/) && (index($line, "MaterializeU4") != 25) Now it works. Any comments are welcome about my practice. Thank you.

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  • Drupal 6: Creating "ON/OFF News Links" functionality for a block created with View Module.

    - by artmania
    Hi friends, I'm a drupal newbie who needs some advice... I have a news list block at homepage, created with View Module. It is listing all added news' title and link. Everything is cool so far. Now I need to add an ON/OFF option at admin side for homepage news block. When the setting is ON, it will work as it is. When it is OFF, only the titles will be listed with no linking to news detail page. So, now where should I add this ON/OFF option? I have only add/edit/delete pages for each news, there is no common news page to add such option. Should I create an admin page with such ON/OFF option in? Also I think I need to create a db table to keep this ON/OFF status. and controlling this value at homepage block, if it is 1 or 0, and displaying links according to db value :/ it looks too long way Create db table Create an page with ON/OFF option in add php codes to update db for admin's choice get the db value in homepage block to display links, etc. is there any shorter, better way to do what I need? Appreciate helps so much!!! Thanks a lot!!

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  • Ext3 fs: Block bitmap for group 1 not in group (block 0). is fs dead?

    - by ip
    My company has a server with one big partition with Mysql database and php files. Now this partition seems to be corrupted, as reported from kernel messages when I tried to mount it manually: [329862.817837] EXT3-fs error (device loop1): ext3_check_descriptors: Block bitmap for group 1 not in group (block 0)! [329862.817846] EXT3-fs: group descriptors corrupted! I've tried to recovery it running tools from a PLD livecd. These are the tools I have tested: - e2retrieve - testdisk - photorec - dd_rescue/dd_rhelp - ddrescue - fsck.ext2 - e2salvage without any success. dumpe2fs 1.41.3 (12-Oct-2008) Filesystem volume name: /dev/sda3 Last mounted on: <not available> Filesystem UUID: dd51610b-6de0-4392-a6f3-67160dbc0343 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal filetype sparse_super Default mount options: (none) Filesystem state: not clean with errors Errors behavior: Continue Filesystem OS type: Linux Inode count: 9502720 Block count: 18987570 Reserved block count: 949378 Free blocks: 11555345 Free inodes: 11858398 First block: 0 Block size: 4096 Fragment size: 4096 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 16384 Inode blocks per group: 512 Last mount time: Wed Mar 24 09:31:03 2010 Last write time: Mon Apr 12 11:46:32 2010 Mount count: 10 Maximum mount count: 30 Last checked: Thu Jan 1 01:00:00 1970 Check interval: 0 (<none>) Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 128 Journal inode: 8 Journal backup: inode blocks dumpe2fs: A block group is missing an inode table while reading journal inode e2fsck 1.41.3 (12-Oct-2008) fsck.ext3: Group descriptors look bad... trying backup blocks... fsck.ext3: A block group is missing an inode table while checking ext3 journal for /dev/sda3 I tried also backup superblocks, same error result. There's any other tools I have to test before considering these disk definitely unrecoverable? Many thanks, ip

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  • Installing Oracle Block Browser and Editor tool (bbed)

    What if you could directly read and manipulate data at the block level? Oracle provides such a tool to do exactly that, but you have to build it yourself. The Block Browser and Editor tool, or bbed for short, is your ticket into the contents of data blocks within an Oracle database.

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  • drupal - using variable_set, hook block and hook menu to save config values then print out in custom

    - by bert
    I am trying to 1) implement the hook menu and variable_set in the block hook and to solicit and store configuration values from user, 2) then use retrieve configuration values and 3) pass them out into a template using theme hook when page is shown. However I need a bit of a push on step two and three! // ===================== file: my_module.php function my_module_block($op = 'list', $delta = 0, $edit = array()) { switch($op) { case 'list': $blocks[0] = array( 'info' => t('Find Something'), // required value - this shows up in your list of blocks 'region' => 'left', // default region on the page 'weight' => 0, // position the block vertically within its column. 'visibility' => 1, // permit the block to be displayed for a given user. 'status' => TRUE, // enabled ); return $blocks; break; // case configure case 'configure': // not used ? // case save (save configuration values) case 'save': variable_set('my_module_text_bottom', $edit['my_module_text_bottom']); variable_set('my_module_text_top', $edit['my_module_text_top']); break; } } function my_module_menu(){ $items = array(); // add menu items $items['my_module'] = array( // add a menu item here... ); // administration setting - callback my_module_admin $items['admin/settings/my_module'] = array( 'title' => 'Lookup on Something', 'description' => 'Description of my module settings page', 'page callback' => 'drupal_get_form', 'page arguments' => array('my_module_admin'), 'access arguments' => array('access administration pages'), 'type' => MENU_NORMAL_ITEM, ); return $items; } // setup administrative default values (see: site configiration) function my_module_admin() { $form = array(); $form['my_module_text_top'] = array( '#type' => 'textarea', '#title' => t('Text of top of page'), '#default_value' => variable_get('my_module_text_top', 'my_module_text_top: This is configurable text found in the module configuration.'), '#size' => 1024, '#maxlength' => 1024, '#description' => t("text above the Find a Retailer block."), '#required' => TRUE, ); $form['my_module_text_bottom'] = array( '#type' => 'textarea', '#title' => t('Text at bottom of page'), '#default_value' => variable_get('my_module_text_bottom', 'my_module_text_bottom: This is configurable text found in the module configuration.'), '#size' => 1024, '#maxlength' => 1024, '#description' => t("text below the Find a Retailer block."), '#required' => TRUE, ); return system_settings_form($form); } // registering a theme function my_module_theme(){ return array( 'my_module_show' => array( 'arguments' => array('content' => "hello"), 'template' => 'my_module_show' ), ); } // implementing a theme function theme_my_module_show($content){ $output = '<ul>$content</ul>'; return $output; } function my_module(){ $output = ''; $variables = ""; $output .= theme('my_module_show', $variables); return $output; } // ===================== file: my_module_show.tpl.php print $text1; print $text2;

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  • How do you code up a pattern matching block in scala?

    - by egervari
    How do you code a function that takes in a block of code that contains case statements? For instance, in my block of code, I don't want to code a match or a default case... looking something like this myApi { case Whatever() => // code for case 1 case SomethingElse() => // code for case 2 } And inside of my myApi(), it'll actually do the matches. Help?

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  • how many processors can I get in a block on cuda GPU?

    - by Vickey
    hi all, I have two questions to ask 1) If I create only one block of threads in cuda and execute the my parallel program on it then is it possible that more than one processors would be given to single block so that my program get some benefit of multiprocessor platform ? 2) can I synchronize the threads of different blocks ? if yes please give some hints. Thanks in advance since I know I'll get replies as always I get.

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  • What is wrong with my @synchronized block?

    - by hyn
    I have 2 threads in my application, a game update thread and render/IO/main thread. My update thread updates the game state, and the render thread renders the scene based on the updated values of the game state models and a few other variables stored inside an object (gameEngine). The render thread gets executed while the game thread is still updating, which is a problem, so it appeared to me the solution is to use @synchronized like this: @synchronized(gameEngine) { [gameEngine update]; nextUpdate = now + GAME_UPDATE_INTERVAL; gameEngine.lastGameUpdateInterval = now - lastUpdate; gameEngine.lastGameUpdateTime = now; lastUpdate = now; } But the render thread still accesses the gameEngine object between -update and the last 3 lines of the block. Why is this?

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  • How to block/avoid a particular IP when connecting to websites?

    - by Mark
    I'm having trouble connecting to a particular website. I can view it through a proxy, but not from home. So I ran a traceroute: Tracing route to fvringette.com [76.74.225.90] over a maximum of 30 hops: 1 <1 ms <1 ms <1 ms <snip> 2 * * * Request timed out. 3 9 ms 7 ms 27 ms rd2bb-ge2-0-0-22.vc.shawcable.net [64.59.146.226] 4 8 ms 7 ms 7 ms rc2bb-tge0-9-2-0.vc.shawcable.net [66.163.69.41] 5 10 ms 9 ms 9 ms rc2wh-tge0-0-1-0.vc.shawcable.net [66.163.69.65] 6 27 ms 23 ms 22 ms ge-gi0-2.pix.van.peer1.net [206.223.127.1] 7 18 ms 18 ms 20 ms 10ge.xe-0-2-0.van-spenc-dis-1.peer1.net [216.187.89.206] 8 9 ms 11 ms 10 ms 64.69.91.245 9 * * * Request timed out. 10 * * * Request timed out. ... Looks like this "64.69.91.245" is somehow blocking me. Can I tell my computer to avoid/bypass that IP when trying to connect?

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  • Creating block devices for openstack deployment using MAAS and juju (nova-volume deployment)

    - by Tom Van Hoof
    Hi, I'm currently trying to get a openstack deployment working by using MAAS with 9 nodes and juju. To do this I found this guide, working with ubuntu 12.04 LTS https://help.ubuntu.com/community/UbuntuCloudInfrastructure and followed it as good as I can. After a vigorous amount of trial and error I finally got to the point where I'm supposed to deploy nova-volume using the "custom" config file. However when my node is started and shows up as running in the "juju status" report the service reports the installation failed. I'm trying to install with juju jitsu by the way. I think it has something to do with the following statement in the openstack.cfg file : nova-volume: # This must be a free block device that is writable on the nova-volume host. block-device: "xvdb" overwrite: "true" I did some research and found that (at least I think) this refers to a Xen Virtual Drive/device, and because the device is not present on the node it's being deployed to, the installation fails. What I don't understand is how I am supposed to have such a block device available on a machine which was completely managed by MAAS. Does anyone here have any experience with this and knows of a way to solve this, or am I missing something big here. Some kind of missing link between the MAAS and a separate XEN host ? My MAAS server is ubuntu 12.04LTS Server. All help is welcome. Kind regards, Tom

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  • How do i make an AJAX block crawlable?

    - by Vikas Gulati
    I have a block with a few tabs. When the user clicks the tab the content of that block get loaded. Now I would like to make it crawlable by the search engines and at the same time I want to maintain the good user-experience. I figured out a couple of alternative but each one has its own shortcomings. The approached that i could come up with. Use hashbangs and then use this. But hashbangs are not good and things of past now. Secondly it will make my content crawlable by only googlebot as yahoo and bing dont support this. Use GET PARAMETERIZED fallback incase when javascript doesn't work. This will work for all bots and also would be nice as it would work without javascript. But then this will create duplicates of my page as this block is only a very small section of my page and i have like around 5-6 tabs. So it means that many duplicates! Doing this without AJAX is not an option as it would only increase the page load time as all these blocks have heavy media content in them!

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  • Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block 0,0

    - by AlbertK
    I've read the following two solution: Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) kernel panic not syncing vfs unable to mount root fs on unknown block oo swapper not tainted ,but still got the same problem. Here's my full error code: [1.902269] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) [1.902299] Pid: 1, comm: swapper/0 Not tainted 3.2.0-29-generic #46-Ubuntu [1.902325] Call Trace: [1.902348] [<ffffffff81640ec8>] panic+0x91/0x1a4 [1.902373] [<ffffffff81cfc01e>] mount_block_root+0xdc/0x18e [1.902400] [<ffffffff81002930>] ? populate_rootfs_wait+0x300/0x9d0 [1.902426] [<ffffffff81cfc257>] mount_root+0x54/0x59 [1.902450] [<ffffffff81cfc3c9>] prepare_namespace+0x16d/0x1a6 [1.902476] [<ffffffff81cfbd63>] kernel_init+0x153/0x158 [1.902501] [<ffffffff81664034>] kernel_thread_helper+0x4/0x10 [1.902527] [<ffffffff81cfbc10>] ? start_kernel+0x3bd/0x3bd [1.902551] [<ffffffff81664030>] ? gs_change+0x13/0x13 I don't know what these error messages mean at all, but I hope that these will help to solve this problem I'm running Ubuntu 12.04. Thanks for any advice.

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  • Preventing multiple repeat selection of synchronized Controls ?

    - by BillW
    The working code sample here synchronizes (single) selection in a TreeView, ListView, and ComboBox via the use of lambda expressions in a dictionary where the Key in the dictionary is a Control, and the Value of each Key is an Action<int. Where I am stuck is that I am getting multiple repetitions of execution of the code that sets the selection in the various controls in a way that's unexpected : it's not recursing : there's no StackOverFlow error happening; but, I would like to figure out why the current strategy for preventing multiple selection of the same controls is not working. Perhaps the real problem here is distinguishing between a selection update triggered by the end-user and a selection update triggered by the code that synchronizes the other controls ? Note: I've been experimenting with using Delegates, and forms of Delegates like Action<T>, to insert executable code in Dictionaries : I "learn best" by posing programming "challenges" to myself, and implementing them, as well as studying, at the same time, the "golden words" of luminaries like Skeet, McDonald, Liberty, Troelsen, Sells, Richter. Note: Appended to this question/code, for "deep background," is a statement of how I used to do things in pre C#3.0 days where it seemed like I did need to use explicit measures to prevent recursion when synchronizing selection. Code : Assume a WinForms standard TreeView, ListView, ComboBox, all with the same identical set of entries (i.e., the TreeView has only root nodes; the ListView, in Details View, has one Column). private Dictionary<Control, Action<int>> ControlToAction = new Dictionary<Control, Action<int>>(); private void Form1_Load(object sender, EventArgs e) { // add the Controls to be synchronized to the Dictionary // with appropriate Action<int> lambda expressions ControlToAction.Add(treeView1, (i => { treeView1.SelectedNode = treeView1.Nodes[i]; })); ControlToAction.Add(listView1, (i => { listView1.Items[i].Selected = true; })); ControlToAction.Add(comboBox1, (i => { comboBox1.SelectedIndex = i; })); } private void synchronizeSelection(int i, Control currentControl) { foreach(Control theControl in ControlToAction.Keys) { // skip the 'current control' if (theControl == currentControl) continue; // for debugging only Console.WriteLine(theControl.Name + " synchronized"); // execute the Action<int> associated with the Control ControlToAction[theControl](i); } } private void treeView1_AfterSelect(object sender, TreeViewEventArgs e) { synchronizeSelection(e.Node.Index, treeView1); } private void listView1_SelectedIndexChanged(object sender, EventArgs e) { // weed out ListView SelectedIndexChanged firing // with SelectedIndices having a Count of #0 if (listView1.SelectedIndices.Count > 0) { synchronizeSelection(listView1.SelectedIndices[0], listView1); } } private void comboBox1_SelectedValueChanged(object sender, EventArgs e) { if (comboBox1.SelectedIndex > -1) { synchronizeSelection(comboBox1.SelectedIndex, comboBox1); } } background : pre C# 3.0 Seems like, back in pre C# 3.0 days, I was always using a boolean flag to prevent recursion when multiple controls were updated. For example, I'd typically have code like this for synchronizing a TreeView and ListView : assuming each Item in the ListView was synchronized with a root-level node of the TreeView via a common index : // assume ListView is in 'Details View,' has a single column, // MultiSelect = false // FullRowSelect = true // HideSelection = false; // assume TreeView // HideSelection = false // FullRowSelect = true // form scoped variable private bool dontRecurse = false; private void treeView1_AfterSelect(object sender, TreeViewEventArgs e) { if(dontRecurse) return; dontRecurse = true; listView1.Items[e.Node.Index].Selected = true; dontRecurse = false; } private void listView1_SelectedIndexChanged(object sender, EventArgs e) { if(dontRecurse) return // weed out ListView SelectedIndexChanged firing // with SelectedIndices having a Count of #0 if (listView1.SelectedIndices.Count > 0) { dontRecurse = true; treeView1.SelectedNode = treeView1.Nodes[listView1.SelectedIndices[0]]; dontRecurse = false; } } Then it seems, somewhere around FrameWork 3~3.5, I could get rid of the code to suppress recursion, and there was was no recursion (at least not when synchronizing a TreeView and a ListView). By that time it had become a "habit" to use a boolean flag to prevent recursion, and that may have had to do with using a certain third party control.

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  • Java Synchronized List Deadlock

    - by portoalet
    From Effective Java 2nd edition item 67 page 266-268: The background thread calls s.removeObserver, which attempts to lock observers, but it can’t acquire the lock, because the main thread already has the lock. All the while, the main thread is waiting for the background thread to finish removing the observer, which explains the deadlock. I am trying to find out which threads deadlock in the main method by using ThreadMXBean (http://stackoverflow.com/questions/1102359/programmatic-deadlock-detection-in-java) , but why does it not return the deadlocked threads? I used a new Thread to run the ThreadMXBean detection. public class ObservableSet<E> extends ForwardingSet<E> { public ObservableSet(Set<E> set) { super(set); } private final List<SetObserver<E>> observers = new ArrayList<SetObserver<E>>(); public void addObserver(SetObserver<E> observer) { synchronized(observers) { observers.add(observer); } } public boolean removeObserver(SetObserver<E> observer) { synchronized(observers) { return observers.remove(observer); } } private void notifyElementAdded(E element) { synchronized(observers) { for (SetObserver<E> observer : observers) observer.added(this, element); } } @Override public boolean add(E element) { boolean added = super.add(element); if (added) notifyElementAdded(element); return added; } @Override public boolean addAll(Collection<? extends E> c) { boolean result = false; for (E element : c) result|=add(element); //callsnotifyElementAdded return result; } public static void main(String[] args) { ObservableSet<Integer> set = new ObservableSet<Integer>(new HashSet<Integer>()); final ThreadMXBean threadMxBean = ManagementFactory.getThreadMXBean(); Thread t = new Thread(new Runnable() { @Override public void run() { while( true ) { long [] threadIds = threadMxBean.findDeadlockedThreads(); if( threadIds != null) { ThreadInfo[] infos = threadMxBean.getThreadInfo(threadIds); for( ThreadInfo threadInfo : infos) { StackTraceElement[] stacks = threadInfo.getStackTrace(); for( StackTraceElement stack : stacks ) { System.out.println(stack.toString()); } } } try { System.out.println("Sleeping.."); TimeUnit.MILLISECONDS.sleep(1000); } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }); t.start(); set.addObserver(new SetObserver<Integer>() { public void added(ObservableSet<Integer> s, Integer e) { ExecutorService executor = Executors.newSingleThreadExecutor(); final SetObserver<Integer> observer = this; try { executor.submit(new Runnable() { public void run() { s.removeObserver(observer); } }).get(); } catch (ExecutionException ex) { throw new AssertionError(ex.getCause()); } catch (InterruptedException ex) { throw new AssertionError(ex.getCause()); } finally { executor.shutdown(); } } }); for (int i = 0; i < 100; i++) set.add(i); } } public interface SetObserver<E> { // Invoked when an element is added to the observable set void added(ObservableSet<E> set, E element); } // ForwardingSet<E> simply wraps another Set and forwards all operations to it.

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  • Decentralized synchronized secure data storage

    - by Alberich
    Introduction Hi, I am going to ask a question which seems utopic for me, but I need to know if there is a way to achieve what I need. And if not, I need to know why not. The idea Suppose I have a database structure, in MySql. I want to create some solution to allow anyone (no matter who, no matter where) to have a synchronized copy (updated clone) of this database (with its content) Well, and it is not going to be just one synchronized copy, it could (and should) be a multiple replication (supposing the basic, this means, for example, ten copies all over the world) And, the most important thing: It must be secure. By secure I mean only real-accepted transactions will be synchronized with all the others (no matter how many) database copies/clones. Note: Since it would be quite difficult to make the synchronization in real-time, I will design everything to make this feature dispensable. So it is not required. My auto-suggestion This is how I am thinking to manage it: Time identifiers and Updates checking: Every action (insert, update, delete...) will be stored as the action instruction itself, associated to the time identifier. [I think better than a DATETIME field, it'll be an INT one, with the number of miliseconds passed from 1st january 2013 on, for example]. So each copy is going to ask to the "neighbour copy" for new actions done since last update, and execute them after checking they are allowed. Problem 1: the "neighbour copy" could be outdated too. Solution 1: do not ask just one neighbour, create a random list with some of the copies/clones and ask them for news (I could avoid the list and ask ALL the clones for updates, but this will be inefficient if clones number ascends too much). Problem 2: Real-time global synchronization is not active. What if... Someone at CLONE_ENTERPRISING inserts a row into TABLE. ... this row goes to every clone ... Someone at CLONE_FIXEMALL deletes this row. ... and at the same time, somewhere in an outdated clone ... Someone at CLONE_DROPOUT edits this row (now inexistent at the other clones) Solution 2: easy stuff, force a GLOBAL synchronization before doing any new "depending-on-third-data action" (edit, for example). This global synch. will be unnecessary when making an INSERT, for instance. Note: Well, someone could have some fun, and make the same insert in two clones... since they're not getting updated in real-time, this row will exist twice. But, it's the same as when we have one single database, in some needed cases we check if there is an existing same-row before doing the final action. Not a problem. Problem 3: It is possible to edit the code and do not filter actions, so someone could spread instructions to delete everything, or just make some trolling activity. This is not a problem, since good clones will always be somewhere. Those who got bad won't interest anymore. I really appreciate if you read. I know this is not the perfect solution, it has possibly hundred of holes, but it is my basic start. I will now appreciate anything you can teach me now. Thanks a lot. PS.: It could be that all this I am trying already exists and has its own name. Sorry for asking then (I'd anyway thank this name, if it exists)

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  • Ext3 fs: Block bitmap for group 1 not in group (block 0). is fs dead?

    - by ip
    Hi, My company has a server with one big partition with Mysql database and php files. Now this partition seems to be corrupted, as reported from kernel messages when I tried to mount it manually: [329862.817837] EXT3-fs error (device loop1): ext3_check_descriptors: Block bitmap for group 1 not in group (block 0)! [329862.817846] EXT3-fs: group descriptors corrupted! I've tried to recovery it running tools from a PLD livecd. These are the tools I have tested: - e2retrieve - testdisk - photorec - dd_rescue/dd_rhelp - ddrescue - fsck.ext2 - e2salvage without any success. dumpe2fs 1.41.3 (12-Oct-2008) Filesystem volume name: /dev/sda3 Last mounted on: <not available> Filesystem UUID: dd51610b-6de0-4392-a6f3-67160dbc0343 Filesystem magic number: 0xEF53 Filesystem revision #: 1 (dynamic) Filesystem features: has_journal filetype sparse_super Default mount options: (none) Filesystem state: not clean with errors Errors behavior: Continue Filesystem OS type: Linux Inode count: 9502720 Block count: 18987570 Reserved block count: 949378 Free blocks: 11555345 Free inodes: 11858398 First block: 0 Block size: 4096 Fragment size: 4096 Blocks per group: 32768 Fragments per group: 32768 Inodes per group: 16384 Inode blocks per group: 512 Last mount time: Wed Mar 24 09:31:03 2010 Last write time: Mon Apr 12 11:46:32 2010 Mount count: 10 Maximum mount count: 30 Last checked: Thu Jan 1 01:00:00 1970 Check interval: 0 (<none>) Reserved blocks uid: 0 (user root) Reserved blocks gid: 0 (group root) First inode: 11 Inode size: 128 Journal inode: 8 Journal backup: inode blocks dumpe2fs: A block group is missing an inode table while reading journal inode There's any other tools I have to test before considering these disk definitely unrecoverable? Many thanks, ip

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  • Block access to specific applications

    - by Jason Aren
    I would like to give several users rights to a computer running Ubuntu to do most administrative functions such as add/remove programs, save files, make settings changes, etc. However, I would like to block them from using several specific applications. Is this possible, and how would I do so? To provide a bit more detail: I am trying to set up Gnome Nanny to block adult websites from my kids' computer. I'd like to give them full access to the computer ACCEPT for Gnome Nanny. Windows has a program called K9 that cannot be turned off or uninstalled unless the user has the password EVEN if the user is an admin. Sounds like this isn't available on Ubuntu without a rather involved process of setting permissions on a large list of applications and functions to mimic admin rights.

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  • Detect block size for quota in Linux

    - by Chen Levy
    The limit placed on disk quota in Linux is counted in blocks. However, I found no reliable way to determine the block size. Tutorials I found refer to block size as 512 bytes, and sometimes as 1024 bytes. I got confused reading a post on LinuxForum.org for what a block size really means. So I tried to find that meaning in the context of quota. I found a "Determine the block size on hard disk filesystem for disk quota" tip on NixCraft, that suggested the command: dumpe2fs /dev/sdXN | grep -i 'Block size' or blockdev --getbsz /dev/sdXN But on my system those commands returned 4096, and when I checked the real quota block size on the same system, I got a block size of 1024 bytes. Is there a scriptable way to determine the quota block size on a device, short of creating a known sized file, and checking it's quota usage?

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  • Programmers Block ?? [closed]

    - by Robert Ventre
    Possible Duplicate: Is there such a thing as Programmer's block? Has anyone had writers block? Currently, I am trying to get back in to a development role but am struggling to develop any apps. I have a good understanding of VB and OOP. I developed last in the first version of .net studio and also foxpro 9. At the moment I have tried building a customer order app, the form and database have been straight forward but I'm struggling with the nuts and bolts of the application. Should it be a Web or Windows application? Should I use classes/modules? All advice is welcome.

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  • Multi Column Block Too Narrow in Chrome

    - by aksarben
    My Web site displays song lyrics in a multi-column format, using CSS3. Both Firefox & MSIE 10+ display the multi-column text perfectly, but Chrome does not. This sample page shows the problem: http://www.hymntime.com/tch/test/html5/html5-multicolumn-test.htm The page uses a media selector, so your Chrome window must be at least 1280 pixels wide to see the effect. In fact, if you make the Chrome window less than 1280 pixels, you'll see the lyrics block change to a single column, of the same overall width. In other words, when Chrome shifts to 1-column to 2-column mode (due to the wider browser window), the lyrics block remains the same width, causing text to be squeezed together. Has anyone else seen this behavior, or know a solution? Is this a Chrome bug, or I am I doing something wrong? I posted this question on a Chrome forum a while back, but got no reply.

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  • Mozilla Firefox 23 Will Block Mixed SSL Content

    - by Anirudha
    Originally posted on: http://geekswithblogs.net/anirugu/archive/2013/07/03/mozilla-firefox-23-will-block-mixed-ssl-content.aspxIf you have a site which is running on SSL and used content that make non-https request then you need to a bit worried. The default setting of Firefox 23 will block the content that called on non-https address and page is based on SSL. for example script using https://code.jquery.com/jquery-1.10.2.min.js will not work because code.jquery.com can not be reach on https. the cdn ajax.googleapis.com support SSL so you can try it. if you want to disable this settings you can modify it on about:config security.mixed_content.block_active_content change the value true to false and it will be disable (it’s just for example)

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  • Can a thread call wait() on two locks at once in Java (6)

    - by Dr. Monkey
    I've just been messing around with threads in Java to get my head around them (it seems like the best way to do so) and now understand what's going on with synchronize, wait() and notify(). I'm curious about whether there's a way to wait() on two resources at once. I think the following won't quite do what I'm thinking of: synchronized(token1) { synchronized(token2) { token1.wait(); token2.wait(); //won't run until token1 is returned System.out.println("I got both tokens back"); } } In this (very contrived) case token2 will be held until token1 is returned, then token1 will be held until token2 is returned. The goal is to release both token1 and token2, then resume when both are available (note that moving the token1.wait() outside the inner synchronized loop is not what I'm getting at). A loop checking whether both are available might be more appropriate to achieve this behaviour (would this be getting near the idea of double-check locking?), but would use up extra resources - I'm not after a definitive solution since this is just to satisfy my curiosity.

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