Search Results

Search found 3093 results on 124 pages for 'weng lock mok'.

Page 23/124 | < Previous Page | 19 20 21 22 23 24 25 26 27 28 29 30  | Next Page >

  • Does this use of Monitor.Wait/Pulse have a race condition?

    - by jw
    I have a simple producer/consumer scenario, where there is only ever a single item being produced/consumed. Also, the producer waits for the worker thread to finish before continuing. I realize that kind of obviates the whole point of multithreading, but please just assume it really needs to be this way (: This code doesn't compile, but I hope you get the idea: // m_data is initially null // This could be called by any number of producer threads simultaneously void SetData(object foo) { lock(x) // Line A { assert(m_data == null); m_data = foo; Monitor.Pulse(x) // Line B while(m_data != null) Monitor.Wait(x) // Line C } } // This is only ever called by a single worker thread void UseData() { lock(x) // Line D { while(m_data == null) Monitor.Wait(x) // Line E // here, do something with m_data m_data = null; Monitor.Pulse(x) // Line F } } Here is the situation that I am not sure about: Suppose many threads call SetData() with different inputs. Only one of them will get inside the lock, and the rest will be blocked on Line A. Suppose the one that got inside the lock sets m_data and makes its way to Line C. Question: Could the Wait() on Line C allow another thread at Line A to obtain the lock and overwrite m_data before the worker thread even gets to it? Supposing that doesn't happen, and the worker thread processes the original m_data, and eventually makes its way to Line F, what happens when that Pulse() goes off? Will only the thread waiting on Line C be able to get the lock? Or will it be competing with all the other threads waiting on Line A as well? Essentially, I want to know if Pulse()/Wait() communicate with each other specially "under the hood" or if they are on the same level with lock(). The solution to these problems, if they exist, is obvious of course - just surround SetData() with another lock - say, lock(y). I'm just curious if it's even an issue to begin with.

    Read the article

  • Why there is no scoped locks for multiple mutexes in C++0x or Boost.Thread?

    - by Vicente Botet Escriba
    C++0x thread library or Boost.thread define non-member variadic template function that lock all lock avoiding dead lock. template <class L1, class L2, class... L3> void lock(L1&, L2&, L3&...); While this function avoid help to deadlock, the standard do not includes the associated scoped lock to write exception safe code. { std::lock(l1,l2); // do some thing // unlock li l2 exception safe } That means that we need to use other mechanism as try-catch block to make exception safe code or define our own scoped lock on multiple mutexes ourselves or even do that { std::lock(l1,l2); std::unique_lock lk1(l1, std::adopted); std::unique_lock lk2(l2, std::adopted); // do some thing // unlock li l2 on destruction of lk1 lk2 } Why the standard doesn't includes a scoped lock on multiple mutexes of the same type, as for example { std::array_unique_lock<std::mutex> lk(l1,l2); // do some thing // unlock l1 l2 on destruction of lk } or tuples of mutexes { std::tuple_unique_lock<std::mutex, std::recursive_mutex> lk(l1,l2); // do some thing // unlock l1 l2 on destruction of lk } Is there something wrong on the design?

    Read the article

  • How to fix the apt-get -f install error [duplicate]

    - by Satish Patel
    This question already has an answer here: How do I fix a “Could not get lock /var/lib/dpkg/lock” problem? 12 answers I am getting continuous error when I run the command sudo apt-get -f install The output of the command is as follows: Reading package lists... Done Building dependency tree Reading state information... Done Correcting dependencies... Done The following extra packages will be installed: default-jre-headless icedtea-7-jre-jamvm openjdk-7-jre openjdk-7-jre-headless openjdk-7-jre-lib Suggested packages: fonts-ipafont-gothic fonts-ipafont-mincho ttf-telugu-fonts ttf-oriya-fonts ttf-kannada-fonts ttf-bengali-fonts The following NEW packages will be installed: default-jre-headless icedtea-7-jre-jamvm openjdk-7-jre openjdk-7-jre-headless openjdk-7-jre-lib 0 upgraded, 5 newly installed, 0 to remove and 28 not upgraded. 2 not fully installed or removed E: Could not get lock /var/cache/apt/archives/lock - open (11: Resource temporarily unavailable) E: Unable to lock directory /var/cache/apt/archives/ satish@satish-Inspiron-N5010 ~ $ please guide ASAP

    Read the article

  • How to prevent my screen from either dimming or the screen-lock starting when watching YouTube?

    - by Steven Roose
    My screen brightness used to dim after a few seconds to preserve battery. This is default in Ubuntu 12.04. However when watching video it should not dim. This works correctly when I watch videos using native applications like VLC. With in-browser video, however, the screen is not prevented from dimming. This is very annoying as you have to move your cursor every 10 seconds or so. I used to use Mac OSX where I had the same dimming settings and Flash videos were taken into account correctly. Anyone an idea how you can make YouTube prevent your screen from dimming?

    Read the article

  • Deadlock Analysis in NetBeans 8

    - by Geertjan
    Lock contention profiling is very important in multi-core environments. Lock contention occurs when a thread tries to acquire a lock while another thread is holding it, forcing it to wait. Lock contentions result in deadlocks. Multi-core environments have even more threads to deal with, causing an increased likelihood of lock contentions. In NetBeans 8, the NetBeans Profiler has new support for displaying detailed information about lock contention, i.e., the relationship between the threads that are locked. After all, whenever there's a deadlock, in any aspect of interaction, e.g., a political deadlock, it helps to be able to point to the responsible party or, at least, the order in which events happened resulting in the deadlock. As an example, let's take the handy Deadlock sample code from the Java Tutorial and look at the tools in NetBeans IDE for identifying and analyzing the code. The description of the deadlock is nice: Alphonse and Gaston are friends, and great believers in courtesy. A strict rule of courtesy is that when you bow to a friend, you must remain bowed until your friend has a chance to return the bow. Unfortunately, this rule does not account for the possibility that two friends might bow to each other at the same time. To help identify who bowed first or, at least, the order in which bowing took place, right-click the file and choose "Profile File". In the Profile Task Manager, make the choices below: When you have clicked Run, the Threads window shows the two threads are blocked, i.e., the red "Monitor" lines tell you that the related threads are blocked while trying to enter a synchronized method or block: But which thread is holding the lock? Which one is blocked by the other? The above visualization does not answer these questions. New in NetBeans 8 is that you can analyze the deadlock in the new Lock Contention window to determine which of the threads is responsible for the lock: Here is the code that simulates the lock, very slightly tweaked at the end, where I use "setName" on the threads, so that it's even easier to analyze the threads in the relevant NetBeans tools. Also, I converted the anonymous inner Runnables to lambda expressions. package org.demo; public class Deadlock { static class Friend { private final String name; public Friend(String name) { this.name = name; } public String getName() { return this.name; } public synchronized void bow(Friend bower) { System.out.format("%s: %s" + " has bowed to me!%n", this.name, bower.getName()); bower.bowBack(this); } public synchronized void bowBack(Friend bower) { System.out.format("%s: %s" + " has bowed back to me!%n", this.name, bower.getName()); } } public static void main(String[] args) { final Friend alphonse = new Friend("Alphonse"); final Friend gaston = new Friend("Gaston"); Thread t1 = new Thread(() -> { alphonse.bow(gaston); }); t1.setName("Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); }); t2.setName("Gaston bows to Alphonse"); t2.start(); } } In the above code, it's extremely likely that both threads will block when they attempt to invoke bowBack. Neither block will ever end, because each thread is waiting for the other to exit bow. Note: As you can see, it really helps to use "Thread.setName", everywhere, wherever you're creating a Thread in your code, since the tools in the IDE become a lot more meaningful when you've defined the name of the thread because otherwise the Profiler will be forced to use thread names like "thread-5" and "thread-6", i.e., based on the order of the threads, which is kind of meaningless. (Normally, except in a simple demo scenario like the above, you're not starting the threads in the same class, so you have no idea at all what "thread-5" and "thread-6" mean because you don't know the order in which the threads were started.) Slightly more compact: Thread t1 = new Thread(() -> { alphonse.bow(gaston); },"Alphonse bows to Gaston"); t1.start(); Thread t2 = new Thread(() -> { gaston.bow(alphonse); },"Gaston bows to Alphonse"); t2.start();

    Read the article

  • What is lightweight lock in distributed shared memory systems?

    - by Kutluhan Metin
    I started reading Tanenbaum's Distributed Systems book a while ago. I read about two phase locking and timestamp reordering in transactions chapter. While having a deeper look from google I heard of lightweight transactions/lightweight transactional memory. But I couldn't find any good explanation and implementation. So what is lightweight memory? What are the benefits of lightweight locks? And how can I implement them?

    Read the article

  • Can the lock function be used to implement thread-safe enumeration?

    - by Daniel
    I'm working on a thread-safe collection that uses Dictionary as a backing store. In C# you can do the following: private IEnumerable<KeyValuePair<K, V>> Enumerate() { if (_synchronize) { lock (_locker) { foreach (var entry in _dict) yield return entry; } } else { foreach (var entry in _dict) yield return entry; } } The only way I've found to do this in F# is using Monitor, e.g.: let enumerate() = if synchronize then seq { System.Threading.Monitor.Enter(locker) try for entry in dict -> entry finally System.Threading.Monitor.Exit(locker) } else seq { for entry in dict -> entry } Can this be done using the lock function? Or, is there a better way to do this in general? I don't think returning a copy of the collection for iteration will work because I need absolute synchronization.

    Read the article

  • Running script constantly in background: daemon, lock file with crontab, or simply loop?

    - by Mauritz Hansen
    I have a Perl script that queries a database for a list of files to process processes the files and then exits Upon startup this script creates a file (let's say script.lock), and upon exit it removes this file. I have a crontab entry that runs this script every minute. If the lockfile exists then the script exits, assuming that another instance of itself is running. The above process works fine but I am not very happy with the robustness of this approach. Specifically, if for some reason the script exits prematurely and the lockfile is not removed then a new instance will not execute properly. I would appreciate some advice on the following: Is using the lock file a good approach or is there a better/more robust way to do this? Is using crontab for this a good idea or could I better write an endless loop with sleep()? Should I use the GNU 'daemon' program or the Perl Proc::Daemon module (or some other equivalent) for this?

    Read the article

  • Online ALTER TABLE in MySQL 5.6

    - by Marko Mäkelä
    This is the low-level view of data dictionary language (DDL) operations in the InnoDB storage engine in MySQL 5.6. John Russell gave a more high-level view in his blog post April 2012 Labs Release – Online DDL Improvements. MySQL before the InnoDB Plugin Traditionally, the MySQL storage engine interface has taken a minimalistic approach to data definition language. The only natively supported operations were CREATE TABLE, DROP TABLE and RENAME TABLE. Consider the following example: CREATE TABLE t(a INT); INSERT INTO t VALUES (1),(2),(3); CREATE INDEX a ON t(a); DROP TABLE t; The CREATE INDEX statement would be executed roughly as follows: CREATE TABLE temp(a INT, INDEX(a)); INSERT INTO temp SELECT * FROM t; RENAME TABLE t TO temp2; RENAME TABLE temp TO t; DROP TABLE temp2; You could imagine that the database could crash when copying all rows from the original table to the new one. For example, it could run out of file space. Then, on restart, InnoDB would roll back the huge INSERT transaction. To fix things a little, a hack was added to ha_innobase::write_row for committing the transaction every 10,000 rows. Still, it was frustrating that even a simple DROP INDEX would make the table unavailable for modifications for a long time. Fast Index Creation in the InnoDB Plugin of MySQL 5.1 MySQL 5.1 introduced a new interface for CREATE INDEX and DROP INDEX. The old table-copying approach can still be forced by SET old_alter_table=0. This interface is used in MySQL 5.5 and in the InnoDB Plugin for MySQL 5.1. Apart from the ability to do a quick DROP INDEX, the main advantage is that InnoDB will execute a merge-sort algorithm before inserting the index records into each index that is being created. This should speed up the insert into the secondary index B-trees and potentially result in a better B-tree fill factor. The 5.1 ALTER TABLE interface was not perfect. For example, DROP FOREIGN KEY still invoked the table copy. Renaming columns could conflict with InnoDB foreign key constraints. Combining ADD KEY and DROP KEY in ALTER TABLE was problematic and not atomic inside the storage engine. The ALTER TABLE interface in MySQL 5.6 The ALTER TABLE storage engine interface was completely rewritten in MySQL 5.6. Instead of introducing a method call for every conceivable operation, MySQL 5.6 introduced a handful of methods, and data structures that keep track of the requested changes. In MySQL 5.6, online ALTER TABLE operation can be requested by specifying LOCK=NONE. Also LOCK=SHARED and LOCK=EXCLUSIVE are available. The old-style table copying can be requested by ALGORITHM=COPY. That one will require at least LOCK=SHARED. From the InnoDB point of view, anything that is possible with LOCK=EXCLUSIVE is also possible with LOCK=SHARED. Most ALGORITHM=INPLACE operations inside InnoDB can be executed online (LOCK=NONE). InnoDB will always require an exclusive table lock in two phases of the operation. The execution phases are tied to a number of methods: handler::check_if_supported_inplace_alter Checks if the storage engine can perform all requested operations, and if so, what kind of locking is needed. handler::prepare_inplace_alter_table InnoDB uses this method to set up the data dictionary cache for upcoming CREATE INDEX operation. We need stubs for the new indexes, so that we can keep track of changes to the table during online index creation. Also, crash recovery would drop any indexes that were incomplete at the time of the crash. handler::inplace_alter_table In InnoDB, this method is used for creating secondary indexes or for rebuilding the table. This is the ‘main’ phase that can be executed online (with concurrent writes to the table). handler::commit_inplace_alter_table This is where the operation is committed or rolled back. Here, InnoDB would drop any indexes, rename any columns, drop or add foreign keys, and finalize a table rebuild or index creation. It would also discard any logs that were set up for online index creation or table rebuild. The prepare and commit phases require an exclusive lock, blocking all access to the table. If MySQL times out while upgrading the table meta-data lock for the commit phase, it will roll back the ALTER TABLE operation. In MySQL 5.6, data definition language operations are still not fully atomic, because the data dictionary is split. Part of it is inside InnoDB data dictionary tables. Part of the information is only available in the *.frm file, which is not covered by any crash recovery log. But, there is a single commit phase inside the storage engine. Online Secondary Index Creation It may occur that an index needs to be created on a new column to speed up queries. But, it may be unacceptable to block modifications on the table while creating the index. It turns out that it is conceptually not so hard to support online index creation. All we need is some more execution phases: Set up a stub for the index, for logging changes. Scan the table for index records. Sort the index records. Bulk load the index records. Apply the logged changes. Replace the stub with the actual index. Threads that modify the table will log the operations to the logs of each index that is being created. Errors, such as log overflow or uniqueness violations, will only be flagged by the ALTER TABLE thread. The log is conceptually similar to the InnoDB change buffer. The bulk load of index records will bypass record locking. We still generate redo log for writing the index pages. It would suffice to log page allocations only, and to flush the index pages from the buffer pool to the file system upon completion. Native ALTER TABLE Starting with MySQL 5.6, InnoDB supports most ALTER TABLE operations natively. The notable exceptions are changes to the column type, ADD FOREIGN KEY except when foreign_key_checks=0, and changes to tables that contain FULLTEXT indexes. The keyword ALGORITHM=INPLACE is somewhat misleading, because certain operations cannot be performed in-place. For example, changing the ROW_FORMAT of a table requires a rebuild. Online operation (LOCK=NONE) is not allowed in the following cases: when adding an AUTO_INCREMENT column, when the table contains FULLTEXT indexes or a hidden FTS_DOC_ID column, or when there are FOREIGN KEY constraints referring to the table, with ON…CASCADE or ON…SET NULL option. The FOREIGN KEY limitations are needed, because MySQL does not acquire meta-data locks on the child or parent tables when executing SQL statements. Theoretically, InnoDB could support operations like ADD COLUMN and DROP COLUMN in-place, by lazily converting the table to a newer format. This would require that the data dictionary keep multiple versions of the table definition. For simplicity, we will copy the entire table, even for DROP COLUMN. The bulk copying of the table will bypass record locking and undo logging. For facilitating online operation, a temporary log will be associated with the clustered index of table. Threads that modify the table will also write the changes to the log. When altering the table, we skip all records that have been marked for deletion. In this way, we can simply discard any undo log records that were not yet purged from the original table. Off-page columns, or BLOBs, are an important consideration. We suspend the purge of delete-marked records if it would free any off-page columns from the old table. This is because the BLOBs can be needed when applying changes from the log. We have special logging for handling the ROLLBACK of an INSERT that inserted new off-page columns. This is because the columns will be freed at rollback.

    Read the article

  • Keep only "lock" a single app open in iOS?

    - by CT.
    Is there anyway to "lock" open a single app in iOS? My use case for this is simple. There are many apps and games designed for children. While these applications are appropriate for children, many other applications installed on an iPad are not. But even more so than protecting them from inappropriate content, I would just like to prevent them from leaving the application. They accidentally hit the home button or multi-touch gesture out of the application. I know you can turn gestures off. Developers also have links to their website or other related applications. Kids are constantly exiting the application and then bringing the device to me asking "Can you get me back into the game?" every couple minutes. How can I hand a child an iPad with "Angry Birds" running and make sure only "Angry Birds" runs? Cydia or jailbreak tweaks welcome. Thanks.

    Read the article

  • Is it possible to re-lock a bitlocker drive?

    - by Sean Edwards
    I'm running a partition with bitlocker on a Windows 7 Ultimate machine, which contains secure data that I have to recover infrequently. Unlocking it to access the data is obviously no problem, but is there a way to re-lock the partition when I'm done? The best I've found so far is this: http://social.technet.microsoft.com/Forums/en-US/w7itprosecurity/thread/41607938-7452-440d-8253-67fe8657bc0f Currently I have a .bat script on that drive that I can run as administrator, and that re-locks the drive, but it feels like kind of a hackish solution. Does anyone have anything better? Any idea when Microsoft might release a fix for this?

    Read the article

  • How Can I Override the Remote Administrator security policy on Android 2.2 so that I can disable the lock screen?

    - by hagope
    On Android 2.2 Froyo, I added my Corporate exchange email account to the phone, however, the security policy set by the "remote administer" requires that I enter a 4-digit PIN at the lock screen and a maximum 10sec idle. How can I hack my Android, through root access or otherwise, such that I do not need to follow this security policy. I am very annoyed at having to enter the PIN every time I want to use the phone, because I open/close it so often through out the day? Please help...I'm so surprised at how difficult it is to find the answer!

    Read the article

  • Does TFS 2010 lock a project collection when it's being cloned?

    - by Hirvox
    We're planning to migrate a project collection currently hosted on TFS 2010 to TFS 2012. We want to keep the current installation running while resolving any issues that might arise, so we need to copy the current project collection to the new server. However, TFS doesn't allow us to attach a restored database backup directly. The database first must be detached from the original TFS installation. We can get around that limitation by cloning the project collection and detaching the clone, but we're not sure whether that would also impact the original project collection. Does TFS lock the original project collection while it's being cloned?

    Read the article

  • Win32 reset event like synchronization class with boost C++

    - by fgungor
    I need some mechanism reminiscent of Win32 reset events that I can check via functions having the same semantics with WaitForSingleObject() and WaitForMultipleObjects() (Only need the ..SingleObject() version for the moment) . But I am targeting multiple platforms so all I have is boost::threads (AFAIK) . I came up with the following class and wanted to ask about the potential problems and whether it is up to the task or not. Thanks in advance. class reset_event { bool flag, auto_reset; boost::condition_variable cond_var; boost::mutex mx_flag; public: reset_event(bool _auto_reset = false) : flag(false), auto_reset(_auto_reset) { } void wait() { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) return; cond_var.wait(LOCK); if (auto_reset) flag = false; } bool wait(const boost::posix_time::time_duration& dur) { boost::unique_lock<boost::mutex> LOCK(mx_flag); bool ret = cond_var.timed_wait(LOCK, dur) || flag; if (auto_reset && ret) flag = false; return ret; } void set() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = true; cond_var.notify_all(); } void reset() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = false; } }; Example usage; reset_event terminate_thread; void fn_thread() { while(!terminate_thread.wait(boost::posix_time::milliseconds(10))) { std::cout << "working..." << std::endl; boost::this_thread::sleep(boost::posix_time::milliseconds(1000)); } std::cout << "thread terminated" << std::endl; } int main() { boost::thread worker(fn_thread); boost::this_thread::sleep(boost::posix_time::seconds(1)); terminate_thread.set(); worker.join(); return 0; } EDIT I have fixed the code according to Michael Burr's suggestions. My "very simple" tests indicate no problems. class reset_event { bool flag, auto_reset; boost::condition_variable cond_var; boost::mutex mx_flag; public: explicit reset_event(bool _auto_reset = false) : flag(false), auto_reset(_auto_reset) { } void wait() { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) { if (auto_reset) flag = false; return; } do { cond_var.wait(LOCK); } while(!flag); if (auto_reset) flag = false; } bool wait(const boost::posix_time::time_duration& dur) { boost::unique_lock<boost::mutex> LOCK(mx_flag); if (flag) { if (auto_reset) flag = false; return true; } bool ret = cond_var.timed_wait(LOCK, dur); if (ret && flag) { if (auto_reset) flag = false; return true; } return false; } void set() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = true; cond_var.notify_all(); } void reset() { boost::lock_guard<boost::mutex> LOCK(mx_flag); flag = false; } };

    Read the article

  • What do I do for dependencies installing wine1.7 on 14.04

    - by user285207
    user@chrubuntu:~$ sudo apt-get install wine1.7 [sudo] password for user: user Sorry, try again. [sudo] password for user: Reading package lists... Done Building dependency tree Reading state information... Done Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: wine1.7 : Depends: wine1.7-i386 (= 1:1.7.19-0ubuntu2~trusty2) but it is not installable Recommends: gnome-exe-thumbnailer but it is not going to be installed or kde-runtime but it is not going to be installed Recommends: ttf-mscorefonts-installer but it is not going to be installed Recommends: fonts-horai-umefont but it is not going to be installed Recommends: fonts-unfonts-core but it is not going to be installed Recommends: ttf-wqy-microhei Recommends: winetricks but it is not going to be installed E: Unable to correct problems, you have held broken packages. user@chrubuntu:~$ Trying to install wine1.7 on Ubuntu 14.04 64 bit, and i'm not sure what this means, help is greatly appreciated. I already ran sudo apt-get update and get this: Reading package lists... Done W: Duplicate sources.list entry http://dl.google.com/linux/chrome/deb/ stable/main amd64 Packages (/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_main_binary-amd64_Packages) W: You may want to run apt-get update to correct these problems So I run apt-get update and: E: Could not open lock file /var/lib/apt/lists/lock - open (13: Permission denied) E: Unable to lock directory /var/lib/apt/lists/ E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied) E: Unable to lock the administration directory (/var/lib/dpkg/), are you root? This is all very stressing because I have been trying to get Wine for the past week and had to reinstall and IT STILL WON'T WORK.

    Read the article

  • Using the Coherence ConcurrentMap Interface (Locking API)

    - by jpurdy
    For many developers using Coherence, the first place they look for concurrency control is the com.tangosol.util.ConcurrentMap interface (part of the NamedCache interface). The ConcurrentMap interface includes methods for explicitly locking data. Despite the obvious appeal of a lock-based API, these methods should generally be avoided for a variety of reasons: They are very "chatty" in that they can't be bundled with other operations (such as get and put) and there are no collection-based versions of them. Locks do directly not impact mutating calls (including puts and entry processors), so all code must make explicit lock requests before modifying (or in some cases reading) cache entries. They require coordination of all code that may mutate the objects, including the need to lock at the same level of granularity (there is no built-in lock hierarchy and thus no concept of lock escalation). Even if all code is properly coordinated (or there's only one piece of code), failure during updates that may leave a collection of changes to a set of objects in a partially committed state. There is no concept of a read-only lock. In general, use of locking is highly discouraged for most applications. Instead, the use of entry processors provides a far more efficient approach, at the cost of some additional complexity.

    Read the article

  • Specifying and applying broad changes to a program

    - by Victor Nicollet
    How do you handle incomplete feature requests, when the ones asking for the feature cannot possibly write a complete request? Consider an imaginary situation. You are a tech lead working on a piece of software that revolves around managing profiles (maybe they're contacts in a CRM-type application, or employees in an HR application), with many operations being directly or indirectly performed on those profiles — edit fields, add comments, attach documents, send e-mail... The higher-ups decide that a lock functionality should be added whereby a profile can be locked to prevent anyone else from doing any operations on it until it's unlocked — this feature would be used by security agents to prevent anyone from touching a profile pending a security audit. Obviously, such a feature interacts with many other existing features related to profiles. For example: Can one add a comment to a locked profile? Can one see e-mails that were sent by the system to the owner of a locked profile? Can one see who recently edited a locked profile? If an e-mail was in the process of being sent when the lock happened, is the e-mail sending canceled, delayed or performed as if nothing happened? If I just changed a profile and click the "cancel" link on the confirmation, does the lock prevent the cancel or does it still go through? In all of these cases, how do I tell the user that a lock is in place? Depending on the software, there could be hundreds of such interactions, and each interaction requires a decision — is the lock going to apply and if it does, how will it be displayed to the user? And the higher-ups asking for the feature probably only see a small fraction of these, so you will probably have a lot of questions coming up while you are working on the feature. How would you and your team handle this? Would you expect the higher-ups to come up with a complete description of all cases where the lock should apply (and how), and treat all other cases as if the lock did not exist? Would you try to determine all potential interactions based on existing specifications and code, list them and ask the higher-ups to make a decision on all those where the decision is not obvious? Would you just start working and ask questions as they come up? Would you try to change their minds and settle on a more easily described feature with similar effects? The information about existing features is, as I understand it, in the code — how do you bridge the gap between the decision-makers and that information they cannot access?

    Read the article

  • break Folder Protection, Folder Guard Lock or Folder in Windows XP?

    - by SonyAdi
    when I'm making a new partition by the partition magic. Then all of a sudden power failure. Unfortunately because my computer is not equipped with UPS (Power supply Uniterruptible), my computer finally died, too. When power is restored, I tried to turn on the computer. Suddenly my computer can not boot normally into windows. Option through safemode and others all I've tried. The result fails, can not boot at all, into safe mode also can not. And I know the cause. Partition Magic did not finish the work and stopped in the middle of the road and cause the transfer of data files or stopped, finally file2 any default windows were destroyed as well. Unfortunately my important data I store in my document. Finally, I take my hard drive to a friend. Hopes to open a computer hard drive through friend, at least I could save my important data, and then I can install window again by reformatting my hard drive is first. I read the hard drive in explorer my friend, complete with their data, but the data of my important data in my document can not get to go because it requires administrator privileges or the original user's default start my windows (my computer) to open my document folder tersebut.Ini actually very similar to the work or Folder Protection Folder Guard. result I was disappointed and almost desperate to get back my important data is. how do i break Folder Protection, Folder Guard Lock or Folder in Windows XP?

    Read the article

  • Can a sub-procedure procedure lock and modify the same rows FOR UPDATE that its calling procedure al

    - by RenderIn
    Will the following code lead to a deadlock or should it work without any problem? I've got something similar and it's working but I didn't think it would. I thought the parent procedure's lock would have resulted in a deadlock for the child procedure but it doesn't seem to be. If it works, why? My guess is that the nested FOR UPDATE is not running into a deadlock because it's smart enough to realize that it is being called by the same procedure that has the current lock. Would this be a deadlock if FOO_PROC was not a nested procedure? DECLARE FOO_PROC(c_someName VARCHAR2) as cursor c1 is select * from awesome_people where person_name = c_someName FOR UPDATE; BEGIN open c1; update awesome_people set person_name = UPPER(person_name); close c1; END FOO_PROC; cursor my_cur is select * from awesome_people where person_name = 'John Doe' FOR UPDATE; BEGIN for onerow in c1 loop FOO_PROC(onerow.person_name); end loop; END;

    Read the article

  • Why slim reader/writer exclusive lock outperformance the shared one?

    - by Jichao
    I have tested the performance of slim reader/writer lock under windows 7 using the codefrom Windows Via C/C++. The result surprised me that the exclusive lock out performance the shared one. Here are the code and the result. unsigned int __stdcall slim_reader_writer_exclusive(void *arg) { //SRWLOCK srwLock; //InitializeSRWLock(&srwLock); for (int i = 0; i < 1000000; ++i) { AcquireSRWLockExclusive(&srwLock); g_value = 0; ReleaseSRWLockExclusive(&srwLock); } _endthreadex(0); return 0; } unsigned int __stdcall slim_reader_writer_shared(void *arg) { int b; for (int i = 0; i < 1000000; ++i) { AcquireSRWLockShared(&srwLock); //b = g_value; g_value = 0; ReleaseSRWLockShared(&srwLock); } _endthreadex(0); return 0; } g_value is a global int volatile variable. Could you kindly explain why this could happen?

    Read the article

  • How do I make a lock that allows only ONE thread to read from the resource ?

    - by mare
    I have a file that holds an integer ID value. Currently reading the file is protected with ReaderWriterLockSlim as such: public int GetId() { _fileLock.EnterUpgradeableReadLock(); int id = 0; try { if(!File.Exists(_filePath)) CreateIdentityFile(); FileStream readStream = new FileStream(_filePath, FileMode.Open, FileAccess.Read); StreamReader sr = new StreamReader(readStream); string line = sr.ReadLine(); sr.Close(); readStream.Close(); id = int.Parse(line); return int.Parse(line); } finally { SaveNextId(id); // increment the id _fileLock.ExitUpgradeableReadLock(); } } The problem is that subsequent actions after GetId() might fail. As you can see the GetId() method increments the ID every single time, disregarding what happens after it has issued an ID. The issued ID might be left hanging (as said, exceptions might occur). As the ID is incremented, some IDs might be left unused. So I was thinking of moving the SaveNextId(id) out, remove it (the SaveNextId() actually uses the lock too, except that it's EnterWriteLock). And call it manually from outside after all the required methods have executed. That brings out another problem - multiple threads might enter the GetId() method before the SaveNextId() gets executed and they might all receive the same ID. I don't want any solutions where I have to alter the IDs after the operation, correcting them in any way because that's not nice and might lead to more problems. I need a solution where I can somehow callback into the FileIdentityManager (that's the class that handles these IDs) and let the manager know that it can perform the saving of the next ID and then release the read lock on the file containing the ID. Essentialy I want to replicate the relational databases autoincrement behaviour - if anything goes wrong during row insertion, the ID is not used, it is still available for use but it also never happens that the same ID is issued. Hopefully the question is understandable enough for you to provide some solutions..

    Read the article

  • How to lock a transaction for reading a row and then inserting in Hibernate?

    - by at
    I have a table with a name and a name_count. So when I insert a new record, I first check what the maximum name_count is for that name. I then insert the record with that maximum + 1. Works great... except with mysql 5.1 and hibernate 3.5, by default the reads don't respect transaction boundaries. 2 of these inserts for the same name could happen at the same time and end up with the same name_count, which completely screws my application! Unfortunately, there are some specific situations where the above is actually fairly common. So what do I do? I assume I can do a pessimistic lock where any row I read is locked for further reading until I commit or roll-back my transaction. Or I can do an optimistic lock with a version column that automatically keeps trying until there are no conflicts? What's the best approach for my situation and how do I specify it in Hibernate 3.5 and mysql 5.1? The above table is massive and accessed frequently.

    Read the article

  • Ubuntu keyboard shortcuts - two-part question

    - by Don
    Background: I come from a Windows background and just started dual-booting Ubuntu (my first Linux experience) about 4 days ago. So my systems are Windows 7/Ubuntu 12.04, and so far I'm loving Ubuntu. I am a dedicated mouse-abolitionist (trackpads are hell) and do most of my browsing and navigation with keyboard shortcuts. However, on switching to Ubuntu, a lot of my keyboard shortcuts are gone, and my productivity has resultantly taken a huge hit anytime I am using Ubuntu. Problem 1: My computer was designed to display on-screen notifications for a second when I hit caps-lock or num-lock, and there are no constant indicators of the lock status (LEDs, etc). In Ubuntu, the keys still worked, but the notifications were gone. Googling got me a tutorial on key-binding(Compiz) and scripts, so now I have capslock and numlock running this script: #!/bin/bash icon="/usr/share/icons/gnome/scalable/devices/keyboard.svg" case $1 in 'scrl') mask=3 key="Scroll" ;; 'num') mask=2 key="Num" ;; 'caps') mask=1 key="Caps" ;; esac value=$(xset q | grep "LED mask" | sed -r "s/.*LED mask:\s+[0-9a-fA-F]+([0-9a-fA-F]).*/\1/") if [ $(( 0x$value & 0x$mask )) == $mask ] then output="$key Lock" output2="On" else output="$key Lock" output2="Off" fi notify-send -i $icon "$output" "$output2" -t 1000 But, whether turning it off or on, the notifications always say that I have turned it on. Is there an easy fix for this, or an easier way to work it to get it do display the CORRECT notifications? Problem 2: I'm not sure if this is because of my keyboard or Ubuntu. In Windows, I use Chrome and use the ctrl+pgUp/pgDwn shortcuts quite a bit to switch between tabs. On my keyboard, I can enter pgUp and pgDwn by either disabling NumLock and hitting 9 or 3 respectively on the 10key. Alternately I can hold the fn key and hit up or down arrow. The first method is the one I very heavily relied upon, and it works in Firefox for Ubuntu, but not in Chrome nor in Chromium. The second method (ctrl + fn + up/down) works fine in Chrome. However, I'd dearly like to find a method to make the first method work. Any suggestions? Thanks in advance for your help. Update: @julien: I've checked the keyboard layout options - I didn't find anything that seemed useful for this goal. @Marty: The script runs once when the button is pressed. In Compiz, I've tied those two keys to the script, so when I press the button, it runs the script with the button pressed as a parameter. Update: @elmicha: Thanks. That one works a lot better, and it even pops an icon into the status bar when caps lock is on. There's still a very slight problem in that if I quickly tap the key twice, the image will show that it has been turned on and then turned off, and the notifaction will come and go from my status area, but the text of both notifications will be "Caps Lock on". Same with Num Lock. However, if the time between presses is long enough for the first notification to disappear, everything displays correctly. Given how quickly the notifications disappear, I don't expect this will pose too much of a problem for me.

    Read the article

< Previous Page | 19 20 21 22 23 24 25 26 27 28 29 30  | Next Page >