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  • Announcing the New Windows Azure Web Sites Shared Scaling Tier

    - by Clint Edmonson
    Windows Azure Web Sites has added a new pricing tier that will solve the #1 blocker for the web development community. The shared tier now supports custom domain names mapped to shared-instance web sites. This post will outline the plan changes and elaborate on how the new pricing model makes Windows Azure Web Sites an even richer option for web development shops of all sizes. Free Shared Reserved # of Sites 10 100 100 Egress 165MB/Day 5GB/Month Included 5GB/Month Included Storage 1GB 1GB 10GB Throttling CPU/Memory/Egress CPU/Memory Unlimited Price Free $.02/hr per site, per instance $.08/hr per core Setting the Stage In June, we released the first public preview of Windows Azure Web Sites, which gave web developers a great platform on which to get web sites running using their web development framework of choice. PHP, Node.js, classic ASP, and ASP.NET developers can all utilize the Windows Azure platform to create and launch their web sites. Likewise, these developers have a series of data storage options using Windows Azure SQL Databases, MySQL, or Windows Azure Storage. The Windows Azure Web Sites free offer enabled startups to get their site up and running on Windows Azure with a minimal investment, and with multiple deployment and continuous integration features such as Git, Team Foundation Services, FTP, and Web Deploy.  The response to the Windows Azure Web Sites offer has been overwhelmingly positive. Since the addition of the service on June 12th, tens of thousands of web sites have been deployed to Windows Azure and the volume of adoption is increasing every week. Preview Feedback In spite of the growth and success of the product, the community has had questions about features lacking in the free preview offer. The main question web developers asked regarding Windows Azure Web Sites relates to the lack of the free offer’s support for domain name mapping. During the preview launch period, customer feedback made it obvious that the lack of domain name mapping support was an area of concern. We’re happy to announce that this #1 request has been delivered as a feature of the new shared plan. New Shared Tier Portal Features In the screen shot below, the “Scale” tab in the portal shows the new tiers – Free, Shared, and Reserved – and gives the user the ability to quickly move any of their free web sites into the shared tier. With a single mouse-click, the user can move their site into the shared tier. Once a site has been moved into the shared tier, a new Manage Domains button appears in the bottom action bar of the Windows Azure Portal giving site owners the ability to manage their domain names for a shared site. This button brings up the domain-management dialog, which can be used to enter in a specific domain name that will be mapped to the Windows Azure Web Site. Shared Tier Benefits Startups and large web agencies will both benefit from this plan change. Here are a few examples of scenarios which fit the new pricing model: Startups no longer have to select the reserved plan to map domain names to their sites. Instead, they can use the free option to develop their sites and choose on a site-by-site basis which sites they elect to move into the shared plan, paying only for the sites that are finished and ready to be domain-mapped Agencies who manage dozens of sites will realize a lower cost of ownership over the long term by moving their sites into reserved mode. Once multi-site companies reach a certain price point in the shared tier, it is much more cost-effective to move sites to a reserved tier.  Long-term, it’s easy to see how the new Windows Azure Web Sites shared pricing tier makes Windows Azure Web Sites it a great choice for both startups and agency customers, as it enables rapid growth and upgrades while keeping the cost to a minimum. Large agencies will be able to have all of their sites in their own instances, and startups will have the capability to scale up to multiple-shared instances for minimal cost and eventually move to reserved instances without worrying about the need to incur continually additional costs. Customers can feel confident they have the power of the Microsoft Windows Azure brand and our world-class support, at prices competitive in the market. Plus, in addition to realizing the cost savings, they’ll have the whole family of Windows Azure features available. Continuous Deployment from GitHub and CodePlex Along with this new announcement are two other exciting new features. I’m proud to announce that web developers can now publish their web sites directly from CodePlex or GitHub.com repositories. Once connections are established between these services and your web sites, Windows Azure will automatically be notified every time a check-in occurs. This will then trigger Windows Azure to pull the source and compile/deploy the new version of your app to your web site automatically. Walk-through videos on how to perform these functions are below: Publishing to an Azure Web Site from CodePlex Publishing to an Azure Web Site from GitHub.com These changes, as well as the enhancements to the reserved plan model, make Windows Azure Web Sites a truly competitive hosting option. It’s never been easier or cheaper for a web developer to get up and running. Check out the free Windows Azure web site offering and see for yourself. Stay tuned to my twitter feed for Windows Azure announcements, updates, and links: @clinted

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  • SVN Error 403 Forbidden

    - by Chris
    I can't figure this out. I try to import a new project into a svn repository from Netbeans and get 403 Forbidden. I just setup svn on my serverbox today. I can get to it through a browser just fine, though its empty as I haven't imported my project yet. Apache's path for html files is /var/www I setup the svn repo in /var/svn This is the structure of /var/svn [root@localhost svn]# ls -lR /var/svn /var/svn: total 4 drwxrwxrwx 7 apache apache 4096 2010-03-26 10:18 repo /var/svn/repo: total 36 drwxrwxrwx 2 apache apache 4096 2010-03-26 09:47 conf drwxrwxrwx 3 apache apache 4096 2010-03-26 10:18 dav drwxrwsrwx 6 apache apache 4096 2010-03-26 11:19 db -rwxrwxrwx 1 apache apache 2 2010-03-26 09:47 format drwxrwxrwx 2 apache apache 4096 2010-03-26 09:47 hooks drwxrwxrwx 2 apache apache 4096 2010-03-26 09:47 locks -rwxrwxrwx 1 apache apache 229 2010-03-26 09:47 README.txt -rwxrwxrwx 1 apache apache 15 2010-03-26 09:47 svnauth -rwxrwxrwx 1 apache apache 43 2010-03-26 09:48 svnpass /var/svn/repo/conf: total 12 -rwxrwxrwx 1 apache apache 1080 2010-03-26 09:47 authz -rwxrwxrwx 1 apache apache 309 2010-03-26 09:47 passwd -rwxrwxrwx 1 apache apache 2279 2010-03-26 09:47 svnserve.conf /var/svn/repo/dav: total 4 drwxrwxrwx 2 apache apache 4096 2010-03-26 11:19 activities.d /var/svn/repo/dav/activities.d: total 0 /var/svn/repo/db: total 48 -rwxrwxrwx 1 apache apache 2 2010-03-26 09:47 current -rwxrwxrwx 1 apache apache 22 2010-03-26 09:47 format -rwxrwxrwx 1 apache apache 1920 2010-03-26 09:47 fsfs.conf -rwxrwxrwx 1 apache apache 5 2010-03-26 09:47 fs-type -rwxrwxrwx 1 apache apache 2 2010-03-26 09:47 min-unpacked-rev -rwxrwxrwx 1 apache apache 4096 2010-03-26 09:47 rep-cache.db drwxrwsrwx 3 apache apache 4096 2010-03-26 09:47 revprops drwxrwsrwx 3 apache apache 4096 2010-03-26 09:47 revs drwxrwsrwx 2 apache apache 4096 2010-03-26 11:19 transactions -rwxrwxrwx 1 apache apache 2 2010-03-26 11:19 txn-current -rwxrwxrwx 1 apache apache 0 2010-03-26 09:47 txn-current-lock drwxrwsrwx 2 apache apache 4096 2010-03-26 11:19 txn-protorevs -rwxrwxrwx 1 apache apache 37 2010-03-26 09:47 uuid -rwxrwxrwx 1 apache apache 0 2010-03-26 09:47 write-lock /var/svn/repo/db/revprops: total 4 drwxrwsrwx 2 apache apache 4096 2010-03-26 09:47 0 /var/svn/repo/db/revprops/0: total 4 -rwxrwxrwx 1 apache apache 50 2010-03-26 09:47 0 /var/svn/repo/db/revs: total 4 drwxrwsrwx 2 apache apache 4096 2010-03-26 09:47 0 /var/svn/repo/db/revs/0: total 4 -rwxrwxrwx 1 apache apache 115 2010-03-26 09:47 0 /var/svn/repo/db/transactions: total 0 /var/svn/repo/db/txn-protorevs: total 0 /var/svn/repo/hooks: total 36 -rwxrwxrwx 1 apache apache 1955 2010-03-26 09:47 post-commit.tmpl -rwxrwxrwx 1 apache apache 1638 2010-03-26 09:47 post-lock.tmpl -rwxrwxrwx 1 apache apache 2267 2010-03-26 09:47 post-revprop-change.tmpl -rwxrwxrwx 1 apache apache 1567 2010-03-26 09:47 post-unlock.tmpl -rwxrwxrwx 1 apache apache 3404 2010-03-26 09:47 pre-commit.tmpl -rwxrwxrwx 1 apache apache 2410 2010-03-26 09:47 pre-lock.tmpl -rwxrwxrwx 1 apache apache 2764 2010-03-26 09:47 pre-revprop-change.tmpl -rwxrwxrwx 1 apache apache 2100 2010-03-26 09:47 pre-unlock.tmpl -rwxrwxrwx 1 apache apache 2758 2010-03-26 09:47 start-commit.tmpl /var/svn/repo/locks: total 8 -rwxrwxrwx 1 apache apache 139 2010-03-26 09:47 db.lock -rwxrwxrwx 1 apache apache 139 2010-03-26 09:47 db-logs.lock I've got httpd.conf loading svn.conf which contains: <Location /svn> DAV on DAV svn #SVNParentPath /var/svn SVNPath /var/svn/repo Authtype Basic AuthName "Subversion" AuthUserFile /var/svn/repo/svnpass Require valid-user AuthzSVNAccessFile /var/svn/repo/svnauth </Location> Full error message is: org.tigris.subversion.javahl.ClientException: RA layer request failed Server sent unexpected return value (403 Forbidden) in response to CHECKOUT request for '/svn/!svn/bln/0' Sorry for the incredibly long post, but I thought more info would be better than less. I've been fidgeting with this problem for a long time now.

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  • Free Python decompiler that is not an online service?

    - by Readonly
    Is there a library or application that can decompile Python 2.4+ bytecode to obtain the source code? A search revealed: http://depython.net - an online service that you need to upload a pyc or pyo file to the dis module - allows you to disassemble, but not decompile bytecode decompile.py - works only for 1.5.2 or 2.0 decompyle - an decompiling online service that you need to pay for and upload your pyc to

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  • Where can I download a free, text-rich dataset?

    - by blee
    I want to do a bit of lightweight testing and bench-marking for full-text search, so the dataset should have the qualities: 10,000 - 100,000 records. good dispersion of English words. In CSV or Excel format--i.e. I don't want to access it via API. Something like books or movies with title and description fields would be perfect. I browsed the UCI Machine Learning Repo, but it was too number-oriented. Thanks!

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  • What is the correct way to synchronize a shared, static object in Java?

    - by johnrock
    This is a question concerning what is the proper way to synchronize a shared object in java. One caveat is that the object that I want to share must be accessed from static methods. My question is, If I synchronize on a static field, does that lock the class the field belongs to similar to the way a synchronized static method would? Or, will this only lock the field itself? In my specific example I am asking: Will calling PayloadService.getPayload() or PayloadService.setPayload() lock PayloadService.payload? Or will it lock the entire PayloadService class? public class PayloadService extends Service { private static PayloadDTO payload = new PayloadDTO(); public static void setPayload(PayloadDTO payload){ synchronized(PayloadService.payload){ PayloadService.payload = payload; } } public static PayloadDTO getPayload() { synchronized(PayloadService.payload){ return PayloadService.payload ; } } ... Is this a correct/acceptable approach ? In my example the PayloadService is a separate thread, updating the payload object at regular intervals - other threads need to call PayloadService.getPayload() at random intervals to get the latest data and I need to make sure that they don't lock the PayloadService from carrying out its timer task

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  • Are there free realtime financial data feeds since the demise of OpenQuant?

    - by Mel Cooper
    Now that the oligopole of market data providers successfully killed OpenQuant, does any alternative to proprietary and expensive subscriptions for realtime market data subsist? Ideally I would like to be able to monitor tick by tick securities from the NYSE, NASDAQ and AMEX (about 6000 symbols). Most vendors put a limit of 500 symbols watchable at the same time, this is unacceptable to me, even if one can imagine a rotation among the 500 symbols ie. making windows of 5 sec. of effective observation out of each minute for every symbol. Currently I'm doing this by a Java thread pool calling Google Finance, but this is unsatisfactory for several reasons, one being that Google doesn't return the volume traded. Any hint much appreciated, Cheers

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  • NSIS takes ownership of IIS system files

    - by Lucas
    I recently encountered an issue with NSIS that I believe is related to an interaction with UAC, but I am at a loss to explain it and I do not know how to prevent it in the future. I have an installer that creates and removes IIS virtual directories using the NsisIIS plugin. The installer appeared worked correctly on my Windows 7 workstation. When the installer was run on a Windows 2008 R2 server it installed properly, but the uninstaller removed all of the virtual directories and put IIS is an unusable state; to the point that I had to remove the Default Web Site and re-add it. What I eventually found was that all of the IIS configuration files under C:\Windows\System32\inetsrv\config had a lock icon on them. Some investigation seem to indicate that this means a user account has taken ownership of the file, however all the files listed SYSTEM as the file owner. I did check a different server that I have not run the installer on, and it does not have the lock icon applied to the IIS files. I have also seen the same lock icon appear on other files that the NSIS installer creates. For instance, I have a Web.Config.tpl file that is processed using the NSIS ReplaceInFile which also appears with the lock icon after the installer finished. After I explicitly grant another user account access to the file, the lock icon goes away. I run the installer under the local Administrator account on the 2008 R2 server, so I do not get the UAC prompt. Here is the relevant code from the install.nsi file RequestExecutionLevel admin Section "Application" APP_SECTION SectionIn RO Call InstallApp SectionEnd Section "un.Uninstaller Section" Delete "$PROGRAMFILES\${PROGRAMFILESDIR}\Uninstall.exe" Call un.InstallApp SectionEnd Function InstallApp File /oname=Web.Config Web.Config.tpl !insertmacro ReplaceInFile Web.Config %CONNECTION_STRING% $CONNECTION_STRING FunctionEnd Function un.InstallApp ReadRegStr $0 HKLM "Software\${REGKEY}" "VirtualDir" NsisIIS::DeleteVDir "$0" Pop $0 FunctionEnd I have three questions stemming from this incident: How did this happen? How can I fix my installer to prevent it from happening again? How can I repair the permissions on the IIS config files.

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  • Debian 5.0 (lenny) apt sources fail?

    - by Tronic
    For the past few days, I couldn't update our apt-sources on Debian 5.0 (lenny). I get the following errors. W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/main/binary-amd64/Packages 404 Not Found [IP: 130.89.148.12 80] W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/contrib/binary-amd64/Packages 404 Not Found [IP: 130.89.148.12 80] W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/non-free/binary-amd64/Packages 404 Not Found [IP: 130.89.148.12 80] W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/main/source/Sources 404 Not Found [IP: 130.89.148.12 80] W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/contrib/source/Sources 404 Not Found [IP: 130.89.148.12 80] W: Failed to fetch http://ftp.debian.org/debian/dists/lenny/non-free/source/Sources 404 Not Found [IP: 130.89.148.12 80] How do I fix this problem? Edit: My current sources are: # Debian Lenny deb http://ftp.de.debian.org/debian/ lenny main non-free contrib deb-src http://ftp.de.debian.org/debian/ lenny main non-free contrib # Debian Lenny Non-US deb http://non-us.debian.org/debian-non-US lenny/non-US main contrib non-free deb-src http://non-us.debian.org/debian-non-US lenny/non-US main contrib non-free # Debian Lenny Security deb http://security.debian.org/ lenny/updates main contrib non-free

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  • Is there an Outlook or Gmail plugin to manage multiple tasks in an email?

    - by Matthew Lock
    I often get client emails containing 10 or more tasks written as text in the email. I know Outlook and Gmail let you turn an email into a single task, but this doesn't help too much when there are 10 tasks in that email. Are there any plugins for Outlook or Gmail that let put checkboxes into the email or something so I can check off each item as they are done? Ideally I'd like the checkboxes/to do items to be inside the email itself so I can see my progress by looking at the email, rather than just letting me copy text from the email into some other task list.

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  • postfix- are these connects in the log anything to worry about?

    - by Lock
    I am noticing the following in my maillog. Lots of these: Sep 10 10:29:56 westc01-01-01 postfix/smtpd[26788]: connect from unknown[85.111.7.182] And these: Sep 10 10:34:58 westc01-01-01 postfix/smtpd[26768]: disconnect from unknown[85.111.7.182] Sep 10 10:34:58 westc01-01-01 postfix/smtpd[26758]: timeout after AUTH from unknown[85.111.7.182] And these: Sep 10 10:29:56 westc01-01-01 postfix/smtpd[26737]: warning: unknown[85.111.7.182]: SASL LOGIN authentication failed: UGFzc3dvcmQ6 Are these anything to worry about?

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  • How do I free SQLServerCE's COM instance from the current running process?

    - by David Thornley
    It's been a while since I touched COM so be nice ;) This is under WindowsCE 5.0 with SQLServerCE 2.0. After calling this to load SQLServerCE 2.0 : - IDBInitialize *pIDBInitialize = NULL; CoCreateInstance(CLSID_SQLSERVERCE_2_0, NULL, CLSCTX_INPROC_SERVER, IID_IDBInitialize, (void**)&pIDBInitialize); Module load occurs for SSCE20.dll which obviously loads the SQLServerCE engine into the process space. What I don't understand is if I do this immediately after :- pIDBInitialize->Release(); I don't see a dll module unload, so that SSCE20.dll (and friends) are still loaded into my process. Now I tried CoFreeUnusedLibraries() which I figure forces COM to purge any unused libraries, but it doesn't seem to do the trick. At runtime I want to be able to completely unload the SQLServerCE 2.0 dll from the process to streamline an upgrade to 3.5SP1. I suspect this has something to do with the shared dll model that Microsoft use under WindowsCE... but, I might be wrong :) Thanks in advance, David.

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  • Can I use this technique to provide free email service for my users?

    - by Naughty.Coder
    I'll let users register their [email protected] ,,, they enter their members area where they can : 1- send emails ( easy to do) 2- receive emails .. for receiving emails , I'll use a catch all email account , read the email and figure to whom it's sent (username), and then I save it on the database with userid of the username who has registerd ! Do I miss something here ... is it really this simple (if I don't have an email server) ?

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  • How to implement List, Set, and Map in null free design?

    - by Pyrolistical
    Its great when you can return a null/empty object in most cases to avoid nulls, but what about Collection like objects? In Java, Map returns null if key in get(key) is not found in the map. The best way I can think of to avoid nulls in this situation is to return an Entry<T> object, which is either the EmptyEntry<T>, or contains the value T. Sure we avoid the null, but now you can have a class cast exception if you don't check if its an EmptyEntry<T>. Is there a better way to avoid nulls in Map's get(K)? And for argument sake, let's say this language don't even have null, so don't say just use nulls.

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  • After Navigate2 Method returns S_OK Stuck at READYSTATE of READYSTATE_LOADING

    - by Stone Free
    I am working on a MFC Document View architecture application which has multiple documents and views and a tabbed window interface. I have been tasked with making an automatic switch to another tab on the press of the OK button in one of the other tabs. When the other tab is clicked on it uses a C++ wrapper over IWebBrowser2 to navigate to a specific web page. When this is done manually by clicking on the tab everything is fine and the webpage within the view loads successfully. In my first attempt at doing this the tab successfully switched in response to a call to AfxGetMainWnd()->SendMessageToDescendants(SOME_MESSAGE, ...); however by sending this windows message at the wrong point the application would crash once control returned because the chain of events caused the (modeless) dialog (*) that sent the message, to no longer exist. I then found the correct place to make the call, but now when the other tab is activated, it no longer displays the webpage as it should. To debug this problem I added code to check the READYSTATE in both the situation where it works and the situation where it does not. When the page fails to load (despite the call to Navigate2 returning S_OK), the READYSTATE just stays at READYSTATE_LOADING. Unfortunately now I am to many edits away from when I had it partially working. I have added TRACE statements to the most obvious events such as OnSetFocus, CView::OnActivateView but all traces come out in the same order despite the behaviour being different * hosted in the view

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  • Printing to a remote printer through the internet

    - by Lock
    I have a remote network (A) that is connected to a head office (B) through a private network. Network A only has 1 PC that requires the connection, and this is into a terminal server at network B. We want to save money by getting rid of the private network as only 1 PC now access it and it seems silly to pay ~$400 per month for something that is accessed by 1 PC. A VPN tunnel is out of the question as the provider wants to charge $600 a month for a VPN tunnel (more than a private network? I might get them to check these numbers). I was thinking of 2 options: 1) VPN client on the PC. This wouldn't cost a thing as we already have VPN users available. 2) Open up a port on the firewall of network B, forwarding to the terminal server. Now the problem is this: On the terminal server, the program that is accessed is for printing labels to the printer that is at network A. The program is setup to send all print jobs to a printer that is setup locally on the terminal server, which has its port mapped to the IP address of the printer that is at network A. If we got rid of the VPN tunnel and used clients/open up firewall port, the printer would no longer be able to find network A, and hence printing would not work. Any ideas to combat this issue? Can the printers at the remote network be setup as internet printers? I've never had any experience with internet printers. Can you open up ports and map to a public static IP address?

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  • Class Self-Reference

    - by Free Bullets
    I have the following code. The angle function needs some information from the class it was called from. What's the best way to do this? class MyScannedRobotEvent extends robocode.ScannedRobotEvent { public int angle(robocode.Robot myRobot) { return (int) Math.toRadians((myRobot.getHeading() + getBearing()) % 360); } } public class MyRobot extends robocode.Robot { int a = angle(**WHATDOIPUTHERE?**) }

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  • How to implement Session timeout in Web Server Side?

    - by Morgan Cheng
    I beheld a web framework implementing in-memory session in this way. The session object is added to Cache with timeout. When the time is out, the session is removed from Cache automatically. To protect race condition, each request should acquire lock on given session object to proceed. Each request will "touch" the session in Cache to refresh the timeout. Everything looks fine, until this scenario is discovered. Say, one operation takes a long time, longer than timeout. Another request comes and wait on session lock which is currently hold by the long-time request. Finally, the long-time request is over, it releases the lock. But, since it already takes longer time than timeout, the session object is already removed from Cache. This is obvious because the only request holding the lock doesn't have a chance to "touch" the session object in cache. The second request gets the lock but cannot retrieve the expired Session object. Oops... To fix this issue, the second request has to re-create the Session object. But, this is just like digging a buried dead body from tomb and try to bring it back to life. It causes buggy code. I'm wondering what's the best way to implement timeout in session to handle such scenario. I know that current platform must have good session mechanism. I just want to know the under-the-hood how.

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  • Using boost locks for RAII access to a semaphore

    - by dan
    Suppose I write a C++ semaphore class with an interface that models the boost Lockable concept (i.e. lock(); unlock(); try_lock(); etc.). Is it safe/recommended to use boost locks for RAII access to such an object? In other words, do boost locks (and/or other related parts of the boost thread library) assume that the Lockable concept will only be modeled by mutex-like objects which are locked and unlocked from the same thread? My guess is that it should be OK to use a semaphore as a model for Lockable. I've browsed through some of the boost source and it "seems" OK. The locks don't appear to store explicit references to this_thread or anything like that. Moreover, the Lockable concept doesn't have any function like whichThreadOwnsMe(). It also looks like I should even be able to pass a boost::unique_lock<MySemaphore> reference to boost::condition_variable_any::wait. However, the documentation is not explicitly clear about the requirements. To illustrate what I mean, consider a bare-bones binary semaphore class along these lines: class MySemaphore{ bool locked; boost::mutex mx; boost::condition_variable cv; public: void lock(){ boost::unique_lock<boost::mutex> lck(mx); while(locked) cv.wait(lck); locked=true; } void unlock(){ { boost::lock_guard<boost::mutex> lck(mx); if(!locked) error(); locked=false; } cv.notify_one(); } // bool try_lock(); void error(); etc. } Now suppose that somewhere, either on an object or globally, I have MySemaphore sem; I want to lock and unlock it using RAII. Also I want to be able to "pass" ownership of the lock from one thread to another. For example, in one thread I execute void doTask() { boost::unique_lock<MySemaphore> lock(sem); doSomeWorkWithSharedObject(); signalToSecondThread(); waitForSignalAck(); lock.release(); } While another thread is executing something like { waitForSignalFromFirstThread(); ackSignal(); boost::unique_lock<MySemaphore>(sem,boost::adopt_lock_t()); doMoreWorkWithSameSharedObject(); } The reason I am doing this is that I don't want anyone else to be able to get the lock on sem in between the time that the first thread executes doSomeWorkWithSharedObject() and the time the second executes doMoreWorkWithSameSharedObject(). Basically, I'm splitting one task into two parts. And the reason I'm splitting the task up is because (1) I want the first part of the task to get started as soon as possible, (2) I want to guarantee that the first part is complete before doTask() returns, and (3) I want the second, more time-consuming part of the task to be completed by another thread, possibly chosen from a pool of slave threads that are waiting around to finish tasks that have been started by master threads. NOTE: I recently posted this same question (sort of) here http://stackoverflow.com/questions/2754884/unlocking-a-mutex-from-a-different-thread-c but I confused mutexes with semaphores, and so the question about using boost locks didn't really get addressed.

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  • Modelling boost::Lockable with semaphore rather than mutex (previously titled: Unlocking a mutex fr

    - by dan
    I'm using the C++ boost::thread library, which in my case means I'm using pthreads. Officially, a mutex must be unlocked from the same thread which locks it, and I want the effect of being able to lock in one thread and then unlock in another. There are many ways to accomplish this. One possibility would be to write a new mutex class which allows this behavior. For example: class inter_thread_mutex{ bool locked; boost::mutex mx; boost::condition_variable cv; public: void lock(){ boost::unique_lock<boost::mutex> lck(mx); while(locked) cv.wait(lck); locked=true; } void unlock(){ { boost::lock_guard<boost::mutex> lck(mx); if(!locked) error(); locked=false; } cv.notify_one(); } // bool try_lock(); void error(); etc. } I should point out that the above code doesn't guarantee FIFO access, since if one thread calls lock() while another calls unlock(), this first thread may acquire the lock ahead of other threads which are waiting. (Come to think of it, the boost::thread documentation doesn't appear to make any explicit scheduling guarantees for either mutexes or condition variables). But let's just ignore that (and any other bugs) for now. My question is, if I decide to go this route, would I be able to use such a mutex as a model for the boost Lockable concept. For example, would anything go wrong if I use a boost::unique_lock< inter_thread_mutex for RAII-style access, and then pass this lock to boost::condition_variable_any.wait(), etc. On one hand I don't see why not. On the other hand, "I don't see why not" is usually a very bad way of determining whether something will work. The reason I ask is that if it turns out that I have to write wrapper classes for RAII locks and condition variables and whatever else, then I'd rather just find some other way to achieve the same effect. EDIT: The kind of behavior I want is basically as follows. I have an object, and it needs to be locked whenever it is modified. I want to lock the object from one thread, and do some work on it. Then I want to keep the object locked while I tell another worker thread to complete the work. So the first thread can go on and do something else while the worker thread finishes up. When the worker thread gets done, it unlocks the mutex. And I want the transition to be seemless so nobody else can get the mutex lock in between when thread 1 starts the work and thread 2 completes it. Something like inter_thread_mutex seems like it would work, and it would also allow the program to interact with it as if it were an ordinary mutex. So it seems like a clean solution. If there's a better solution, I'd be happy to hear that also. EDIT AGAIN: The reason I need locks to begin with is that there are multiple master threads, and the locks are there to prevent them from accessing shared objects concurrently in invalid ways. So the code already uses loop-level lock-free sequencing of operations at the master thread level. Also, in the original implementation, there were no worker threads, and the mutexes were ordinary kosher mutexes. The inter_thread_thingy came up as an optimization, primarily to improve response time. In many cases, it was sufficient to guarantee that the "first part" of operation A, occurs before the "first part" of operation B. As a dumb example, say I punch object 1 and give it a black eye. Then I tell object 1 to change it's internal structure to reflect all the tissue damage. I don't want to wait around for the tissue damage before I move on to punch object 2. However, I do want the tissue damage to occur as part of the same operation; for example, in the interim, I don't want any other thread to reconfigure the object in such a way that would make tissue damage an invalid operation. (yes, this example is imperfect in many ways, and no I'm not working on a game) So we made the change to a model where ownership of an object can be passed to a worker thread to complete an operation, and it actually works quite nicely; each master thread is able to get a lot more operations done because it doesn't need to wait for them all to complete. And, since the event sequencing at the master thread level is still loop-based, it is easy to write high-level master-thread operations, as they can be based on the assumption that an operation is complete when the corresponding function call returns. Finally, I thought it would be nice to use inter_thread mutex/semaphore thingies using RAII with boost locks to encapsulate the necessary synchronization that is required to make the whole thing work.

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  • How to free member (i.e BSTR, SAFEARRAY, VARIANT) of an IDL User Defined Structure which is encapsul

    - by Picaro De Vosio
    Hi, I have a structure defined in IDL. This structure has following members: { BSTR m_sFirst; BSTR m_sSecond; VARIANT m_vChildStruct; //This member encapsulate a sub structure SAFEARRAY __RPC_FAR * m_saArray; }CustomINFO; I am allocating the memory for the structs using CoTaskMemAlloc and encapsulating it in Variant as follows: vV-vt = VT_RECORD; vV-pvRecord = pStruct; //Pointer of sturct vV-pRecInfo = pRI; //RecordInfo Interface Is it enough to call VariantClear to deallocate the memory of struct and its members? Will it also release the IRecordInfo interface? Or i have to manually get the encapsulated struct and deallocate each member myself and then use CoTaskMemFree to deallocate sturct. Thanks Picaro De Vosio

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