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  • Is there any software or hardware which lets you stop, slow down, speed up or even reverse time?

    - by tjrobinson
    Obviously I'm talking about time in terms of the PC clock rather than real time. We were testing an application we've developed at work by setting the clock forward and back to simulate different scenarios and I started thinking how useful it would be if you could adjust the rate(?) of the system clock with finer control. So you could make a minute pass in a second or a day pass in 30 seconds and watch how the program you're developing copes with changes in date and time. I'd be interested to hear if anyone knows of any software or hardware which can let you do some or all of the above.

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  • How is thread synchronization implemented, at the assembly language level?

    - by Martin
    While I'm familiar with concurrent programming concepts such as mutexes and semaphores, I have never understood how they are implemented at the assembly language level. I imagine there being a set of memory "flags" saying: lock A is held by thread 1 lock B is held by thread 3 lock C is not held by any thread etc But how is access to these flags synchronized between threads? Something like this naive example would only create a race condition: mov edx, [myThreadId] wait: cmp [lock], 0 jne wait mov [lock], edx ; I wanted an exclusive lock but the above ; three instructions are not an atomic operation :(

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  • How to use locks/synchronization here

    - by MasterGberry
    I have this code block here and i need to make sure the rankedPlayersWaitingForMatch is synchronized between threads properly. I was going to use synchronize but that i don't think will work here because of the variable being used in the if statement. I read online about final Lock lock = new ReentrantLock(); but I am a bit confused on how to use it in this case properly with the try/finally block. Can I get a quick example? Thanks // start synchronization if (rankedPlayersWaitingForMatch.get(rankedType).size() >= 2) { Player player1 = rankedPlayersWaitingForMatch.get(rankedType).remove(); Player player2 = rankedPlayersWaitingForMatch.get(rankedType).remove(); // end synchronization // ... I don't want this all to be synchronized, just after the first 2 remove() } else { // end synchronization // ... }

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  • Multithreaded UI desktop application issues

    - by igor
    I am involved into development a rich UI project: desktop windows application. Application uses asynchronous invocations and in its turn it should be ready to process external messages (events). The problem is clear: at first time it was built as a simple prototype and it was not stress tested and all was fine. Then application was grown: the number of calls to server and number of events from server are high and performance is low. What is more users noticed that sometimes performance is extremal low. Asynchronous invocations based on thread pool (BeginInvoke, EndInvoke), external events are going from WCF service (.NET 3.5). My goal is synchronization of all tasks and putting priorities to every executions in desktop application. My question is: is there any practice how to reach my goal: patterns, task priority list, others? What should I do at first, second and next times? Thanks

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  • Multithreded UI desktop application issues

    - by igor
    I am involved into development a rich UI project: desktop windows application. Application uses asynchronous invocations and in its turn it should be ready to process external messages (events). The problem is clear: at first time it was built as a simple prototype and it was not stress tested and all was fine. Then application was grown: the number of calls to server and number of events from server are high and performance is low. What is more users noticed that sometimes performance is extremal low. Asynchronous invocations based on thread pool (BeginInvoke, EndInvoke), external events are going from WCF service (.NET 3.5). My goal is synchronization of all tasks and putting priorities to every executions in desktop application. My question is: is there any practice how to reach my goal: patterns, task priority list, others? What should I do at first, second and next times? Thanks

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  • Is there any way to synchronize AD users with Office 365 but still be able to edit them online?

    - by Massimo
    I'm performing a migration to Office 365 from a third-party mail server (MDaemon); the local Active Directory doesn't include any Exchange server, and never had any. We will need directory synchronization in order to enable users to log on to Office 365 using their domain credentials; but it seems that as soon as you enable directory synchronization, you can't perform any action anymore on Office 365 users: all changes need to be made on the local Active Directory, and then replicated by the synchronization process. For ordinary users with a single e-mail address and standard features, this is not a big problem; but what about users which need an additional address? What if I need to configure some nonstandard setting, like "hide from address list" or a custom mailbox quota? From what I've gathered, the only supported way to do this, as you can't directly edit Office 365 objects anymore after synchronization is enabled, is to extend the local AD schema with Exchange attributes, and then manually edit them (!). Or, you can install at least one local Exchange server, and then use the Exchange administrative tools to configure the required settings. Is this correct or am I missing something? Is there any way to synchronize user accounts and password, but still be able to edit user settings directly in Office 365? If not (everything really needs to be set locally and then synchronized), is there any simpler way to do this than manually editing LDAP attributes or installing a local Exchange server?

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  • Variable-step update() in game loop is falling behind, how can I get around this?

    - by ThatsGobbles
    I'm working on a minimal game engine for my next game. I'm using the delta update method like shown: void update(double delta) { // Update code that uses `delta` goes here } I have a deep hierarchy of updatable objects, with a root updatable that contains several updatables, each of which contains more updatables, etc. Normally I'd just iterate through each of the root's children and update each one, which would then do the same for its children, and so on. However, passing a fixed value of delta to the root means that by the time the leaf updatables are reached, it's been longer since delta seconds that have elapsed. This is causing noticable desyncing in my game, and time synchronization is very important in my case (I'm working on a rhythm game). Any ideas on how I should tackle this? I've considered using StopWatches and a global readable timer, but any advice would be helpful. I'm also open to moving to fixed timesteps as opposed to variable.

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  • Variable-step update() in game loop is falling behind, how can I get around this?

    - by ThatsGobbles
    I'm working on a minimal game engine for my next game. I'm using the delta update method like shown: void update(double delta) { // Update code that uses `delta` goes here } I have a deep hierarchy of updatable objects, with a root updatable that contains several updatables, each of which contains more updatables, etc. Normally I'd just iterate through each of the root's children and update each one, which would then do the same for its children, and so on. However, passing a fixed value of delta to the root means that by the time the leaf updatables are reached, it's been longer since delta seconds that have elapsed. This is causing noticable desyncing in my game, and time synchronization is very important in my case (I'm working on a rhythm game). Any ideas on how I should tackle this? I've considered using StopWatches and a global readable timer, but any advice would be helpful. I'm also open to moving to fixed timesteps as opposed to variable.

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  • P2V conversion using Synchronization

    - by vitea1
    I'm currently P2Ving over my 2003 exchange server and would like to know the best way to use the synchronization feature? I already P2V'd this server over about 5 times and had great success without any outages of service etc. I would like to set it up where just as it finishes the full clone that it starts synchronizing the change automatically. How and can I set this up and what is the best version? I'm using version 4.0. Thanks.

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  • Best approach for Synchronization Mysql databases using C# [closed]

    - by nirmal90
    I have a requirement as below. Windows application in c# with MySQL database MySQL database in both local and server One centralized server with many client synchronizing the server database at each time when the new entry or update is happen in local machine The server data also needs to be updated in local at regular intervals in order to avoid conflicts I need to know what is the best approach to follow to make this synchronization without any conflicts.

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  • Trying to set PC clock programmatically just before Daylight Saving Time ends

    - by Moe Sisko
    To reproduce : 1) Add Microsoft.VisualBasic assembly to your project reference 2) Change PC timezone to : (GMT+10:00) Canberra, Melbourne, Sydney . Ensure PC is set to automatically adjust clock for daylight savings time. (For this timezone, daylight savings time ends at 3am on 4 Apr 2010.) 3) add following code : public void SetNewDateTime(DateTime dt) { Microsoft.VisualBasic.DateAndTime.Today = dt; // ignores time component Microsoft.VisualBasic.DateAndTime.TimeOfDay = dt; // ignores date component } private void button1_Click(object sender, EventArgs e) { DateTime dt = new DateTime(2010, 4, 5, 5, 0, 0); // XX SetNewDateTime(dt); // XX System.Threading.Thread.Sleep(500); DateTime dt2 = new DateTime(2010, 4, 4, 1, 0, 0); SetNewDateTime(dt2); } 4) When button 1 is clicked, the PC clock eventually shows 2am, whereas 1 am was expected. (If code marked at "XX" is removed, the clock sometimes shows the correct time of 1 am). Any idea what is happening ? (Or is there a more reliable way of setting the PC clock from C# code ?) TIA.

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  • Did I implement clock drift properly?

    - by David Titarenco
    I couldn't find any clock drift RNG code for Windows anywhere so I attempted to implement it myself. I haven't run the numbers through ent or DIEHARD yet, and I'm just wondering if this is even remotely correct... void QueryRDTSC(__int64* tick) { __asm { xor eax, eax cpuid rdtsc mov edi, dword ptr tick mov dword ptr [edi], eax mov dword ptr [edi+4], edx } } __int64 clockDriftRNG() { __int64 CPU_start, CPU_end, OS_start, OS_end; // get CPU ticks -- uses RDTSC on the Processor QueryRDTSC(&CPU_start); Sleep(1); QueryRDTSC(&CPU_end); // get OS ticks -- uses the Motherboard clock QueryPerformanceCounter((LARGE_INTEGER*)&OS_start); Sleep(1); QueryPerformanceCounter((LARGE_INTEGER*)&OS_end); // CPU clock is ~1000x faster than mobo clock // return raw return ((CPU_end - CPU_start)/(OS_end - OS_start)); // or // return a random number from 0 to 9 // return ((CPU_end - CPU_start)/(OS_end - OS_start)%10); } If you're wondering why I Sleep(1), it's because if I don't, OS_end - OS_start returns 0 consistently (because of the bad timer resolution, I presume). Basically, (CPU_end - CPU_start)/(OS_end - OS_start) always returns around 1000 with a slight variation based on the entropy of CPU load, maybe temperature, quartz crystal vibration imperfections, etc. Anyway, the numbers have a pretty decent distribution, but this could be totally wrong. I have no idea.

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  • AMD Opteron BSOD - A clock interrupt was not received on a secondary processor within the allocatio

    - by laurens
    On one of our servers we got an -for me new- BSOD with the error message: "A clock interrupt was not received on a secondary processor within the allocation time interval" The server's specs: HP XW9400 2x Dual-Core AMD Opeteron 2224 SE 3,20Ghz (4CPUs) 16GB HP ECC RAM Windows 2008 R2 Enterprise 64bit Nvidia Quadro 4xxx graphics (?) Sounds familiar to someone ? Thanks in advance

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  • Interaction between for loops with clock function?!

    - by learningtolive
    Can someone explain me the exact interaction in context of delay between the two for loops with clock function. How does for1 interact with for2 on the cout statement(30 on 640000000)? start=clock(); cout<<endl<<start<<endl; for(delay=0; delay<30; delay++) for(i=0; i<640000000; i++); end=clock(); cout<<end<<endl; cout<<"Num of ticks for non reg-loop: "; cout<<end-start<<'\n';

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  • Accurate clock in Erlang

    - by buddhabrot
    I was thinking about how to implement a process that gives the number of discrete intervals in time that occurred since it started. Am I losing accuracy here? How do I implement this without loss of accuracy after a while and after heavy client abuse. I am kind of stumped how to do this in Erlang. -module(clock). -compile([export_all]). start(Time) -> register(clock, spawn(fun() -> tick(Time, 0) end)). stop() -> clock ! stop. tick(Time, Count) -> receive nticks -> io:format("~p ticks have passed since start~n", [Count]) after 0 -> true end, receive stop -> void after Time -> tick(Time, Count + 1) end.

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  • Implementation details of database synchronisation API

    - by Daniel
    I want to achieve a database synchronisation between my server database and a client application. The server would run MySQL and the applications may run different database technologies, their implementation isn't important. I have a MySQL database online and web accessible via an API I wrote in PHP (just a detail). My client application ships with a copy of the online data. As time passes my goal is to check for any changes in the online database and make these updates available to the client app via an API call, by sending a date to an API endpoint corresponding to the last date the app was updated, the response would be a JSON filled with all new objects and updated objects, and delete IDs, this makes possible to update the local store appropriately. Essentially I want to do this: http://dbconvert.com/synchronization.php My question is about the implementation details. Would I need to add a column to my database tables with a "last modified" date? Since the client app could be very out of date if it's been offline for a long time, does that also mean I shouldn't delete data from the online database but instead have another column called "delete" set to 1 and a modified date updated appropriately? Would my SQL query simply check for all data with a modified date superior then the date passed into the API request by the client? I feel like there's a lot more to it then having a ton of dates everywhere. And also, worry that I will need to persist a lot of old data in order to ensure that old versions of the client app always have the opportunity to delete parts of their data when they are able to sync.

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  • MVC pattern synchronisation

    - by Hariprasad
    I am facing a problem in synchronizing my model and view threads I have a view which is table. In it, user can select a few rows. I update the view as soon as the user clicks on any row since I don't want the UI to be slow. This updating is done by a logic which runs in the controller thread below. At the same time, the controller will update the model data too, which takes place in a different thread. i.e., controller puts the query in a queue, which is then executed by the model thread - which is a single-threaded interface. As soon as the query executes, controller will get a signal. Now, In order to keep the view and model synchronized, I will update the view again based on the return value of the query (the data returned by model) - even though I updated the view already for that user action. But, I am facing issues because, its taking a lot of time for the model to return the result, by that time user would have performed multiple clicks. So, as a result of updating the view again based on the information from model, the view sometimes goes back to the state in which the previous clicks were made (Suppose user clicks thrice on different rows. I update the view as soon as the click happens. Also, I update the view when I get data back from the model - which is supposed to be same as the already updated state of the view. Now, when the user clicks third time, I get data for the first click from model. As a result, view goes back to a state which is generated by the first click) Is there any way to handle such a synchronization issue?

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  • How to sync client and server at the first frame

    - by wheelinlight
    I'm making a game where an authoritative server sends information to all clients about states and positions for objects in a 3d world. The player can control his character by clicking on the screen to set a destination for the character, much like in the Diablo series. I've read most information I can find online about interpolation, reconciliation, and general networking architecture (Valve's for instance). I think I understand everything but one thing seems to be missing in every article I read. Let say we have an interpolation delay of 100ms, server tickrate=50ms, latency=200ms; How do I know when 100ms has past on the client? If the server sends the first update on t=0, can I assume it arrives at t=200, therefore assuming that all packets takes the same amount of time to reach the client? What if the first packet arrives a little quick, for instance at t=150. I would then be starting the client with t=150 and at t=250 it will think it has past 100ms since its connect to the server when it in fact only 50ms has past. Hopefully the above paragraph is understandable. The summarized question would be: How do I know at what tick to start simulating the client? EDIT: This is how I ended up doing it: The client keeps a clock (approximately) in sync with the server. The client then simulates the world at simulationTime = syncedTime - avg(RTT)/2 - interpolationTime The round-trip time can fluctuate so therefore I average it out over time. By only keeping the most recent values when calculating the average I hope to adapt to more permanent changes in latency. It's still to early to draw any conclusion. I'm currently simulating bad network connections, but it's looking good so far. Anyone see any possible problems?

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  • How to fix windows new line character on sftp synchronization in eclipse (pdt)

    - by superspace
    Hello, I have a problem with windows new line characters being introduced into text files on eclipse sftp synchronization (via jcraft's sftp plugin). I've set "New text file line delimiter" to Unix and have even sanitized the file with "fromdos" but every time i upload using the sftp plugin, windows new line characters can be seen in the remote file as "^M" characters (when viewed in vi). A point to note is that if i upload using an external sftp client, it's all fine. Eclipse Version: PDT (Helios) SFTP: jcraft sftp plugin Local Environment: Ubuntu 10.04 Remote Environments: FreeBSD 6.4, Debian 4.0 What am i missing? My co-workers would thank you for the solution :) Thanks in advance.

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  • Certificate Revocation checking affecting system performance [migrated]

    - by Colm Clarke
    I have a .NET 3.5 desktop application that had been showing periodic slow downs in functionality whenever the test machine it was on was out of the office. I managed to replicate the error on a machine in the office without an internet connection, but it was only when i used ANTS performance profiler that i got a clearer picture of what was going on. In ANTS I saw a "Waiting for synchronization" taking up to 16 seconds that corresponded to the delay I could see in the application when NHibernate tried to load the System.Data.SqlServerCE.dll assembly. If I tried the action again immediately it would work with no delay but if I left it for 5 minutes then it would be slow to load again the next time I tried it. From my research so far it appears to be because the SqlServerCE dll is signed and so the system is trying to connect to get the certificate revocation lists and timing out. Disabling the "Automatically detect settings" setting in the Internet Options LAN settings makes the problem go away, as does disabling the "Check for publishers certificate revocation". But the admins where this application will be deployed are not going to be happy with the idea of disabling certificate checking on a per machine or per user basis so I really need to get the application level disabling of the CRL check working. There is the well documented bug in .net 2.0 which describes this behaviour, and offers a possible fix with a config file element. <?xml version="1.0" encoding="utf-8"?> <configuration> <runtime> <generatePublisherEvidence enabled="false"/> </runtime> </configuration> This is NOT working for me however even though I am using .net 3.5. The SQLServerCE dll is being loaded dynamically by NHibernate and I wonder if the fact that it's dynamic could somehow be why the setting isn't working, but I don't know how I could check that. Can anyone offer suggestions as to why the config setting might not work? Or is there another way I could disable the check at the application level, perhaps a CAS policy setting that I can use to set an exception for the application when it's installed? Or is there something I can change in the application to up the trust level or something like that? I have also tried using to no advantage ServicePointManager.CheckCertificateRevocationList = false; http://rusanu.com/2009/07/24/fix-slow-application-startup-due-to-code-sign-validation/ I have also tried those registry settings out and unfortunately they didn't help. The dlls that appear to be the cause of the hold up are native SQL Server CE dlls, and looking at the stack traces in ProcMon mscorwks.dll doesn't appear to be involved even though the checks on crypto and cert registry keys are being done under the .NET application. It's definitely still something to do with publisher certificate checking because unticking "Check for publisher revocation certificate" still works but something odd is going on.

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  • XNA: Networking gone totally out of sync

    - by MesserChups
    I'm creating a multiplayer interface for a game in 2D some of my friends made, and I'm stuck with a huge latency or sync problem. I started by adapting my game to the msdn xna network tutorial and right now when I join a SystemLink network session (1 host on PC and 1 client on Xbox) I can move two players, everything is ok, but few minutes later the two machines start being totally out of synchronization. When I move one player it takes 10 or 20 seconds (increasing with TIME) to take effect on the second machine. I've tried to : Create a thread which calls NetworkSession.Update() continuously as suggested on this forum, didn't worked. Call the Send() method one frame on 10, and the receive() method at each frame, didn't worked either. I've cleaned my code, flushed all buffers at each call and switched the host and client but the problem still remain... I hope you have a solution because I'm running out of ideas... Thanks SendPackets() code : protected override void SendPackets() { if ((NetworkSessionState)m_networkSession.SessionState == NetworkSessionState.Playing) //Only while playing { //Write in the packet manager m_packetWriter.Write(m_packetManager.PacketToSend.ToArray(), 0, (int)m_packetManager.PacketToSend.Position); m_packetManager.ResetPacket(); //flush //Sends the packets to all remote gamers foreach (NetworkGamer l_netGamer in m_networkSession.RemoteGamers) { if (m_packetWriter.Length != 0) { FirstLocalNetGamer.SendData(m_packetWriter, SendDataOptions.None, l_netGamer); } } m_packetWriter.Flush();//m m_packetWriter.Seek(0, 0); } } ReceivePackets() code : public override void ReceivePackets() { base.ReceivePackets(); if ((NetworkSessionState)m_networkSession.SessionState == NetworkSessionState.Playing) //Only while playing { if (m_networkSession.LocalGamers.Count > 0) //Verify that there's at least one local gamer { foreach (LocalNetworkGamer l_localGamer in m_networkSession.LocalGamers) { //every LocalNetworkGamer must read to flush their stream // Keep reading while packets are available. NetworkGamer l_oldSender = null; while (l_localGamer.IsDataAvailable) { // Read a single packet, even if we are the host, we must read to clear the queue NetworkGamer l_newSender; l_localGamer.ReceiveData(m_packetReader, out l_newSender); if (l_newSender != l_oldSender) { if ((!l_newSender.IsLocal) && (l_localGamer == FirstLocalNetGamer)) { //Parsing PacketReader to MemoryStream m_packetManager.Receive(new MemoryStream(m_packetReader.ReadBytes(m_packetReader.Length))); } } l_oldSender = l_newSender; m_packetReader.BaseStream.Flush(); m_packetReader.BaseStream.Seek(0, SeekOrigin.Begin); } } m_packetManager.ParsePackets(); } } }

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  • how to cause linux system datetime to run faster than real world datetime?

    - by JamesThomasMoon1979
    Background I want to monitor a running linux system over several days. It's a custom gentoo build and with much custom software on board. This software has ongoing maintenance timers and cron scripts and other clock driven events. I need to verify these scheduled events are working. Problem Waiting for the system to step through daily and weekly activity is a long wait time. And modifying all clock-based timers on the system would be time consuming. Yet, I often want to test a system's end-to-end scheduled activities without waiting a week. Potential Solution Have the linux system under test appear to run through it's daily cycle of activity within just a few hours. My Question for Serverfault Is there a way to cause the system's time to run faster than real world time? My first thought is manipulating the ntp daemon to repeatedly and smoothly increment the clock . Any other ideas? And yes, I know this may have strange side affects. However, the system has no important or time critical interactions with systems outside of itself. And this may be a valuable testing technique.

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  • What units does the ntp drift file use?

    - by arielf
    When the ntpd daemon is running, the file: /var/lib/ntp/ntp.drift gets updated periodically. Example: 17:20 hostname 118 ~> ls -l /var/lib/ntp/ntp.drift -rw-r--r-- 1 ntp ntp 7 May 20 16:46 /var/lib/ntp/ntp.drift # So it looks like it was last updated ~34 minutes ago The file has one number in it, for example, looking at a 4 virtual hosts, I find these values, respectively: -22.086 -10.214 -13.669 6.045 I assume these are seconds per day(?), but not sure. man ntpd mentions a different drift file /etc/ntp.drift which doesn't seem to exist. The man page doesn't explain what units are being used for the drift. Questions: Is /etc/ntp.drift actually /var/lib/ntp/ntp.drift on Ubuntu? What units is the drift expressed in? Thanks!

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  • Understanding GPU clock rates

    - by trizicus
    I know how to overclock my CPU (mess with multiplier, and bus speed)... However, I've noticed that it seems a bit more complicated with GPU's. How and where do I start? I've noticed that I can adjust the GPU clock speed in my BIOS. Card I'm overclocking: http://www.nvidia.com/object/product_geforce_gt_240_us.html I found that memory bus speed is (Mem Speed * Bus width) / 8. So obviously a good way to overclock the memory bandwidth is to adjust the memory speed. Now, GPU speed is 550 Mhz. How do I find its speed as well? Do I multiply it by the bus width (128)? What is ideal GPU speed relative to memory bandwidth?

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