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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• The long road to bug-free software

  - by Tony Davis

  The past decade has seen a burgeoning interest in functional programming languages such as Haskell or, in the Microsoft world, F#. Though still on the periphery of mainstream programming, functional programming concepts are gradually seeping into the imperative C# language (for example, Lambda expressions have their root in functional programming). One of the more interesting concepts from functional programming languages is the use of formal methods, the lofty ideal behind which is bug-free software. The idea is that we write a specification that describes exactly how our function (say) should behave. We then prove that our function conforms to it, and in doing so have proved beyond any doubt that it is free from bugs. All programmers already use one form of specification, specifically their programming language's type system. If a value has a specific type then, in a type-safe language, the compiler guarantees that value cannot be an instance of a different type. Many extensions to existing type systems, such as generics in Java and .NET, extend the range of programs that can be type-checked. Unfortunately, type systems can only prevent some bugs. To take a classic problem of retrieving an index value from an array, since the type system doesn't specify the length of the array, the compiler has no way of knowing that a request for the "value of index 4" from an array of only two elements is "unsafe". We restore safety via exception handling, but the ideal type system will prevent us from doing anything that is unsafe in the first place and this is where we start to borrow ideas from a language such as Haskell, with its concept of "dependent types". If the type of an array includes its length, we can ensure that any index accesses into the array are valid. The problem is that we now need to carry around the length of arrays and the values of indices throughout our code so that it can be type-checked. In general, writing the specification to prove a positive property, even for a problem very amenable to specification, such as a simple sorting algorithm, turns out to be very hard and the specification will be different for every program. Extend this to writing a specification for, say, Microsoft Word and we can see that the specification would end up being no simpler, and therefore no less buggy, than the implementation. Fortunately, it is easier to write a specification that proves that a program doesn't have certain, specific and undesirable properties, such as infinite loops or accesses to the wrong bit of memory. If we can write the specifications to prove that a program is immune to such problems, we could reuse them in many places. The problem is the lack of specification "provers" that can do this without a lot of manual intervention (i.e. hints from the programmer). All this might feel a very long way off, but computing power and our understanding of the theory of "provers" advances quickly, and Microsoft is doing some of it already. Via their Terminator research project they have started to prove that their device drivers will always terminate, and in so doing have suddenly eliminated a vast range of possible bugs. This is a huge step forward from saying, "we've tested it lots and it seems fine". What do you think? What might be good targets for specification and verification? SQL could be one: the cost of a bug in SQL Server is quite high given how many important systems rely on it, so there's a good incentive to eliminate bugs, even at high initial cost. [Many thanks to Mike Williamson for guidance and useful conversations during the writing of this piece] Cheers, Tony.

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• ./a.out termniated . Garbage output due to smashing of stack . How to remove this error ?

  - by mekasperasky

  #include <iostream> #include <fstream> #include <cstring> using namespace std; typedef unsigned long int WORD; /* Should be 32-bit = 4 bytes */ #define w 32 /* word size in bits */ #define r 12 /* number of rounds */ #define b 16 /* number of bytes in key */ #define c 4 /* number words in key */ /* c = max(1,ceil(8*b/w)) */ #define t 26 /* size of table S = 2*(r+1) words */ WORD S [t],L[c]; /* expanded key table */ WORD P = 0xb7e15163, Q = 0x9e3779b9; /* magic constants */ /* Rotation operators. x must be unsigned, to get logical right shift*/ #define ROTL(x,y) (((x)<<(y&(w-1))) | ((x)>>(w-(y&(w-1))))) #define ROTR(x,y) (((x)>>(y&(w-1))) | ((x)<<(w-(y&(w-1))))) void RC5_ENCRYPT(WORD *pt, WORD *ct) /* 2 WORD input pt/output ct */ { WORD i, A=pt[0]+S[0], B=pt[1]+S[1]; for (i=1; i<=r; i++) { A = ROTL(A^B,B)+S[2*i]; B = ROTL(B^A,A)+S[2*i+1]; } ct [0] = A ; ct [1] = B ; } void RC5_DECRYPT(WORD *ct, WORD *pt) /* 2 WORD input ct/output pt */ { WORD i, B=ct[1], A=ct[ 0]; for (i=r; i>0; i--) { B = ROTR(B-S [2*i+1],A)^A; A = ROTR(A-S [2*i],B)^B; } pt [1] = B-S [1] ;pt [0] = A-S [0]; } void RC5_SETUP(unsigned char *K) /* secret input key K 0...b-1] */ { WORD i, j, k, u=w/8, A, B, L [c]; /* Initialize L, then S, then mix key into S */ for (i=b-1,L[c-1]=0; i!=-1; i--) L[i/u] = (L[i/u]<<8)+K[ i]; for (S [0]=P,i=1; i<t; i++) S [i] = S [i-1]+Q; for (A=B=i=j=k=0; k<3*t; k++,i=(i+1)%t,j=(j+1)%c) /* 3*t > 3*c */ { A = S[i] = ROTL(S [i]+(A+B),3); B = L[j] = ROTL(L[j]+(A+B),(A+B)); } } void printword(WORD A) { WORD k; for (k=0 ;k<w; k+=8) printf("%c"); } int main() { WORD i, j, k,ptext, pt1 [2], pt2 [2], ct [2] = {0,0}; ifstream in("key1.txt"); ifstream in1("plt.txt"); ofstream out1("cpt.txt"); if(!in) { cout << "Cannot open file.\n"; return 1; } if(!in1) { cout << "Cannot open file.\n"; return 1; } unsigned char key[b]; in >> key; in1 >> pt1[0]; in1 >> pt1[0]; if (sizeof(WORD)!=4) printf("RC5 error: WORD has %d bytes.\n",sizeof(WORD)); RC5_SETUP(key); RC5_ENCRYPT(pt1,ct); printf("\n plaintext "); printword(pt1 [0]); printword(pt1 [1]); printf(" ---> ciphertext "); printword(ct [0]); printword(ct [1]); printf("\n"); RC5_SETUP(key); RC5_DECRYPT(ct,pt2); out1<<ct[0]; out1<<ct[1]; out1 <<"\n"; printf("\n plaintext "); printword(pt1 [0]); printword(pt1 [1]); return 0; } Let the plt.txt file contain 101 100 let the key be 111

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• hibernate not picking sessionFactory

  - by Satya

  My application-context.xml is <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd"> <beans> <bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close"> <property name="driverClassName"><value>com.mysql.jdbc.Driver</value></property> <property name="url"><value>jdbc:mysql://localhost:3306/myDB</value></property> <property name="username"><value>myUser</value></property> <property name="password"><value>myUser</value></property> </bean> <bean id="mySessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean"> <property name="mappingResources"> <property name="dataSource"><ref bean="myDataSource"/></property> <list> <value>com/x/model/config/hibernate/user.hbm.xml</value> </list> </property> <property name="hibernateProperties" > <value> hibernate.dialect=org.hibernate.dialect.MySQLDialect </value> </property> </bean> <bean id="userdao" class="com.x.y.z.UserDao"> <property name="sessionFactory"><ref bean="mySessionFactory"/></property> </bean> </beans> user.hbm.xml is <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.cpt.model"> <class name="User" table="user"> <id name="userId" column="id"> <generator class="native"/> </id> <property name="firstname" column="firstName" /> <property name="lastName" column="lastName"/> <property name="login" column="login"/> <property name="pass" column="pass"/> <property name="superemail" column="superEmail"/> </class> </hibernate-mapping> and the UserDao is package com.x.y.z; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.sql.Statement; import org.hibernate.HibernateException; import org.hibernate.Session; import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.orm.hibernate.support.HibernateDaoSupport; import org.springframework.stereotype.Component; import com.x.model.User; @Component public class UserDao { private SessionFactory sessionFactory; public void addUser(User user) { Session session; try { try { session = getSessionFactory().openSession(); // session = sessionFactory.openSession(); session.save(user); } catch (RuntimeException e) { // TODO Auto-generated catch block e.printStackTrace(); } } catch (HibernateException e) { // TODO Auto-generated catch block System.out.println("printing in the catch"); e.printStackTrace(); } } public SessionFactory getSessionFactory() { System.out.println("returning session factory ::: sessionFactory == null :: "+sessionFactory.openSession()); return sessionFactory; } public void setSessionFactory(SessionFactory sessionFactory) { System.out.println("this is setting session factory" + sessionFactory.getClass()); System.out.println("setting session factory ::: sessionFactory == null :: "+sessionFactory==null); this.sessionFactory = sessionFactory; System.out.println("setting session factory ::: sessionFactory == null :: "+this.sessionFactory.openSession().getClass()); System.out.println(getSessionFactory().openSession().isOpen()); } } However, I keep getting 14:45:09,929 INFO [org.hibernate.impl.SessionFactoryImpl] building session fact ory 14:45:09,933 WARN [net.sf.ehcache.config.Configurator] No configuration found. Configuring ehcache from ehcache-failsafe.xml found in the classpath: vfs:/C:/jb /server/default/deploy/C.war/WEB-INF/lib/ehcache-1.1.jar/ehcache-failsafe.xml 14:45:10,007 INFO [org.hibernate.impl.SessionFactoryObjectFactory] Not binding factory to JNDI, no JNDI name configured 14:45:10,008 INFO [org.hibernate.impl.SessionFactoryImpl] Checking 0 named quer ies 14:45:10,017 INFO [STDOUT] this is setting session factoryclass $Proxy178 14:45:10,017 INFO [STDOUT] false 14:45:10,019 INFO [STDOUT] setting session factory ::: sessionFactory == null : : class org.hibernate.impl.SessionImpl 14:45:10,020 INFO [STDOUT] returning session factory ::: sessionFactory == null :: org.hibernate.impl.SessionImpl(PersistentContext[entitiesByKey={}] ActionQue ue[insertions=[] updates=[] deletions=[] collectionCreations=[] collectionRemova ls=[] collectionUpdates=[]]) It is giving sessionFactory null . Any Idea where am I failing ? Thanks

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• varnish3, mod_geoip with apache2 using mod_rewrite and mod_rpaf

  - by mursalat

  I am maintaining a website with 3 different versions of the site, with 3 different languages, handles with a single system written in php, which takes in environment variables based on the domain name that is being accessed. These are the three sites: myshop.com : english international version myshop.eu : european version of site myshop.ru : russian version of the site when myshop.com is accessed from russia it is to be redirected to myshop.ru, and any country from europe accesses myshop.com, is redirected to myshop.eu, and international visitors stay at myshop.com, although they can go to the country specific site. All these redirections for the country is done using GeoIP apache2 mod in order to determine the country code, which is used in a RewriteCondition to state a RewriteRule, there are some exceptions of IPs that do not do the rewrite for, basically the IPs of the developer's PCs. The site has been doing just fine, until we decided to setup varnish to give the site a boost, it really did give it a great boost, but the country specific rewrites has become buggy. What started to happen is that a russian visitor can go to myshop.com and won't be redirected, until he clicks a random link (perhaps a link not cached by varnish yet) and the user is redirected to their specific country. For that i setup mod_rpaf, and for exceptions to the rewrite rule (for the developer's ip), i used this RewriteCond %{HTTP:X-FORWARDED-FOR} !^43\.43\.43\.43, and i restarted varnish and apache2, it worked for a while, then it messed up again. And whole day i have been doing changes however i have little no clue as to what's going on, sometimes it works, and sometimes it doesn't, and sometimes it half works, etc... As for geoip, i used a php to check the $_SERVER variable, and here is the general idea of the output [HTTP_X_FORWARDED_FOR] => 43.43.43.44 [HTTP_X_VARNISH] => 1705675599 [SERVER_ADDR] => 127.0.0.1 [SERVER_PORT] => 80 [REMOTE_ADDR] => 43.43.43.44 [GEOIP_ADDR] => 43.43.43.44 [GEOIP_CONTINENT_CODE] => EU [GEOIP_COUNTRY_CODE] => FR [GEOIP_COUNTRY_NAME] => France Now, thanks to the "random" redirects, i hardly have a clue as to what is going on, so can you guys please give me some ideas as to what tools to use to debug this? I have tried to see the redirect logs, but they really dont show much, and varnishlog isn't helping much either - although i must admit i am no professional at varnish. I believe the problem is with varnish trying to cache the url, and thus apache redirects are not being done properly, however visits the site first has a redirect, and based on that other users are served the content, depending on from where the user was when the cache was last updated, is it correct? if so, how can i solve the problem? Also, i have the option of using geoip redirects on varnish3 instead of using apache2 to do the redirects, is that what the best practice is? Any suggestion as to debugging this or to fix this would be helpful! thnx!

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• HP F2180 driver installation fails on 64-bit Windows 7

  - by Noam Gal

  Hello; I am trying to install the HP Deskjet AIO (non-network) driver on my machine, which is running the 64-bit version of Windows 7. Before installing it, Windows detected my printer just fine... But I wanted to use the HP scanning application, because tt allows me to scan several photos at once. I ran the DJ_AIO_NonNetwork_ENU_NB file I got from their site, and the installation went almost without a problem... However, at the part where it should have detected the printer, it didn't, so I skipped it - telling the installer I'll connect the printer later. After it was finished I was able to use it regularly, and also scan using the wanted HP application. However, the installer kept popping at random intervals, and giving me an error message. Yesterday I tried removing all the installed HP Applications, and installing from scratch. Running the same installer setup, it now insists that it does not support my operating system, and that 64-bit Vista is the highest it can go... I just don't understand why this is occuring all of the sudden. Has anybody here successfully installed the AIO driver on the 64-bit version of Windows 7? UPDATE: Been chatting with HP chat support over the weekend. Managed to really mess up my windows. At first, they told me to uninstall using an "unintall_l3" batch file inside their installer package, and then reinstall. Didn't work. Also the "l4" batch didn't make any difference. Afterwards I was told to install "Windows install clean up" and remove many hp entries (most of which were not listed on my computer), and I also removed many other hp entries I bumped upon. Then my office 2k7 started failing. I searched around the web, and ran Security Restore, so now my office works, but my windows explorer is all buggy - can't seem to open windows explorer - it hangs while trying to load my hard drives, or completely ignores them and just shows my libraries. Anyone here has any idea how I can restore my win7 to normal, with or without the annoying scanner? UPDATE 2: Ok - explorer back to normal. I guess I just had to wait until it finishes searching while opening the windows explorer for the first time after the Security Restore. Scanner still not working though.

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• DLINK WBR-1310B Wireless Router seems to hang...

  - by Ira Baxter

  I have a brand new DLINK-1310B Wireless Router (box never before opened, although I bought it at the neighborhood computer junk store). I am using it at home (and in fact am using it at this instant from a wireless laptop). When operative, I can ping it at 192.168.0.1, and I can log into it from the PC attached to it by LAN and from the wireless PC at //192.168.0.1. In the course of the day since I've installed, it seems to have locked up 3 times. Each time the symptoms are my web browser (or other IP service, e.g., POP3) stops with a "No internet connection" error. Attempts to contact the router via 192.168.0.1 get no reaction, from either the wireless laptop or from the hardwired PC sitting next to it. It doesn't respond to pings to that address either. Power cycling the router fixes it. I've seen discussion in other questions about aging cheap electronics. Its too new to be aged. Anybody else seen this behavior with a DLINK-1310? Or do I just need to exchange it for another and try again? (I hate rolling dice, I bought the DLINK because a previous Linksys died of apparant heating problems, how many do I have to cycle through before I get something that works and is long-term stable?). Remarkably, nobody talks about how much software is in a router. Is the stuff just buggy? EDIT: Happened again, while I was working on the wireless Vista laptop. (Seems like once an hour?) I was a little more careful this time. The wireless laptop can ping it. It can't get the login screen. I visited the LAN-connected PC (takes me a minute to walk from the laptop to the PC at the other end of the house), and attempted to visit a random web page. Surprise, that worked! And, now, after a minute walking back to the laptop, I can reconnect the wireless laptop, and get to the login page from it. Strange the time/date has been reset back to 2002. (I'll swear I set it and saved the system configuration after updating the firmware; it made me redo every other bit of reconfiguration again). Is there something funny about wireless leases expiring? The router says the leases it is handing out are good for 180 minutes, and the delay-to-inaccessible was only about an hour. The DSL connection seems to have a 10 minute lease.

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• load-causing processes disappearing from "top" ps -o pcpu shows bogus numbers

  - by Alec Matusis

  I administer a large number of servers, and I have this problem only with Ubuntu 10.04 LTS: I run a server under normal load (say load average 3.0 on an 8-core server). The "top" command shows processes taking certain % of CPU that cause this load average: say PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 11008 mysql 20 0 25.9g 22g 5496 S 67 76.0 643539:38 mysqld ps -o pcpu,pid -p11008 %CPU PID 53.1 11008 , everything is consistent. The all of the sudden, the process causing the load average disappears from "top", but the process continues to run normally (albeit with a slight performance decrease), and the system load average becomes somewhat higher. The output of ps -o pcpu becomes bogus: # ps -o pcpu,pid -p11008 %CPU PID 317910278 1587 This happened to at least 5 different severs (different brand new IBM System X hardware), each running different software: one httpd 2.2, one mysqld 5.1, and one Twisted Python TCP servers. Each time the kernel was between 2.6.32-32-server and 2.6.32-40-server. I updated some machines to 2.6.32-41-server, and it has not happened on those yet, but the bug is rare (once every 60 days or so). This is from an affected machine: top - 10:39:06 up 73 days, 17:57, 3 users, load average: 6.62, 5.60, 5.34 Tasks: 207 total, 2 running, 205 sleeping, 0 stopped, 0 zombie Cpu(s): 11.4%us, 18.0%sy, 0.0%ni, 66.3%id, 4.3%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 74341464k total, 71985004k used, 2356460k free, 236456k buffers Swap: 3906552k total, 328k used, 3906224k free, 24838212k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 805 root 20 0 0 0 0 S 3 0.0 1493:09 fct0-worker 982 root 20 0 0 0 0 S 1 0.0 111:35.05 fioa-data-groom 914 root 20 0 0 0 0 S 0 0.0 884:42.71 fct1-worker 1068 root 20 0 19364 1496 1060 R 0 0.0 0:00.02 top Nothing causing high load is showing on top, but I have two highly loaded mysqld instances on it, that suddenly show crazy %CPU: #ps -o pcpu,pid,cmd -p1587 %CPU PID CMD 317713124 1587 /nail/encap/mysql-5.1.60/libexec/mysqld and #ps -o pcpu,pid,cmd -p1624 %CPU PID CMD 2802 1624 /nail/encap/mysql-5.1.60/libexec/mysqld Here are the numbers from # cat /proc/1587/stat 1587 (mysqld) S 1212 1088 1088 0 -1 4202752 14307313 0 162 0 85773299069 4611685932654088833 0 0 20 0 52 0 3549 27255418880 5483524 18446744073709551615 4194304 11111617 140733749236976 140733749235984 8858659 0 552967 4102 26345 18446744073709551615 0 0 17 5 0 0 0 0 0 the 14th and 15th numbers according to man proc are supposed to be utime %lu Amount of time that this process has been scheduled in user mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK). This includes guest time, guest_time (time spent running a virtual CPU, see below), so that applications that are not aware of the guest time field do not lose that time from their calculations. stime %lu Amount of time that this process has been scheduled in kernel mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK). On a normal server, these numbers are advancing, every time I check the /proc/PID/stat. On a buggy server, these numbers are stuck at a ridiculously high value like 4611685932654088833, and it's not changing. Has anyone encountered this bug?

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• VirtualBox Port Forward not working when Guest IP *IS* specified (while doc says opposite)

  - by Patrick

  Trying to port forward from host (Mac OS X) 127.0.0.1:8282 - guest (CentOS)'s 10.10.10.10:8080. Existing port forwards include 127.0.0.1:8181 and 9191 to guest without any IP specified (so whatever it gets through DHCP, as explained in the documentation). Here is how the non-working binding was added: VBoxManage modifyvm "VM name" --natpf1 "rule3,tcp,127.0.0.1,8282,10.10.10.10,8080" Here is how the working ones were added: VBoxManage modifyvm "VM name" --natpf1 "rule1,tcp,127.0.0.1,8181,,80" VBoxManage modifyvm "VM name" --natpf1 "rule2,tcp,127.0.0.1,9191,,9090" And by "non-working", I of course mean not listening (as a prerequisite to forwarding): $ lsof -Pi -n|grep Virtual|grep LISTEN VirtualBo 27050 user 21u IPv4 0x2bbdc68fd363175d 0t0 TCP 127.0.0.1:9191 (LISTEN) VirtualBo 27050 user 22u IPv4 0x2bbdc68fd0e0af75 0t0 TCP 127.0.0.1:8181 (LISTEN) There should be a similar line above but with 127.0.0.1:8282. Just to be clear, this port is listening perfectly fine on the guest itself. And when I remove the guest IP (i.e., clear the 10.10.10.10) the forward works fine, albeit to eth0 (not eth1 where I need it). I can tcpdump and watch the traffic flow back and forth. And yes, I've disabled iptables entirely while testing -- it's not getting blocked anywhere on the guest. As VirtualBox writes in their documentation, you are required to specify the guest IP if it's static (makes sense, no DHCP record it keeps): "If for some reason the guest uses a static assigned IP address not leased from the built-in DHCP server, it is required to specify the guest IP when registering the forwarding rule:". However, doing so (as I need to), seems to break the port forward with nary a report in any log file I can find. (I've reviewed everything in ~/Library/VirtualBox/). Other notes: While I used the above command to add the third rule, I've also verified it showed up correctly in GUI and then removed/re-added from there just to make sure). This forum link -- while very dated -- looks somewhat related in that a port forward to a static IP was not appearing (perhaps they think due to lack of gratuitous arp being sent for host to know IP is there/avail?). Anyway, what gives? Is this still buggy? Any suggestions? If not, easy enough workarounds? What's interesting is that this works perfectly fine on another user's Mac, however he's running a slightly older version (4.3.6 v. 4.3.12).

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• Switching efficiently between windows, not apps, in OS X

  - by Vultan

  Previous questions have asked "how can I efficiently switch between windows, not applications, in OS X"? (Switching windows on OS X, Switch between windows on Mac OS X? and others). The most recommended suggestions seem to be: Use some combo of cmd-tab and cmd-~. Use Expose, and possibly Spaces Use Witch I spent the money on Witch, and have been using it for a few weeks; it's ok, but it is sometimes slow to respond, sometimes buggy on window order, crashes my system if I disable and re-enable it too many times, and doesn't work properly with X11 apps. The built-in cmd-tab and cmd-~ are ok, but still bring an entire application to the forefront. I find a very common workflow I use is to bounce back and forth between two windows (for example, a browser window and a Thunderbird email in progress), when both apps (the browser and email software) have multiple windows open. I can use Cmd-Tab to get back and forth between apps, but whenever I switch to an app, ALL windows from that app pop up. That suddenly fills my screen with irrelevant data and windows, and often drops those other windows in front of the single window from the other app that I was using and would conveniently like to keep viewing even though it isn't in focus. Expose seems to be the preferred "OS X natural way," but I can't seem to get myself to use it efficiently. I hit F9, and see 10 windows; I then need to squint, try to find the window I want, then use the mouse or the cursor keys to navigate to the one I want. Given the number of power users who say they use Expose, I must be missing the boat here. My goal is not to make this a repeat of previous questions. I'm not asking "what are my alternatives?" (unless I've missed one above!) Rather, I'm asking: what are you, OS X power users, actually doing to handle the use case I described above? Another common use case for me is having multiple Excel spreadsheets open and multiple browser windows open, and I'm rapidly switching back and forth between one spreadsheet in particular and one browser window. Every time I Cmd-Tab, all spreadsheets or all browser windows appear: I don't want to see the ones I'm not working with, and they tend to hide the windows from the alternative app that I don't have in focus but I'd like to at least eyeball. Can you describe what your workflow is like, and how you rapidly and thoughtlessly switch between windows from apps that have multiple windows open?

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• DBCC CHECKDB (BatmanDb, REPAIR_ALLOW_DATA_LOSS) &ndash; Are you Feeling Lucky?

  - by David Totzke

  I’m currently working for a client on a PowerBuilder to WPF migration.  It’s one of those “I could tell you, but I’d have to kill you” kind of clients and the quick-lime pits are currently occupied by the EMC tech…but I’ve said too much already. At approximately 3 or 4 pm that day users of the Batman[1] application here in Gotham[1] started to experience problems accessing the application.  Batman[2] is a document management system here that also integrates with the ERP system.  Very little goes on here that doesn’t involve Batman in some way.  The errors being received seemed to point to network issues (TCP protocol error, connection forcibly closed by the remote host etc…) but the real issue was much more insidious. Connecting to the database via SSMS and performing selects on certain tables underlying the application areas that were having problems started to reveal the issue.  You couldn’t do a SELECT * FROM MyTable without it bombing and giving the same error noted above.  A run of DBCC CHECKDB revealed 14 tables with corruption.  One of the tables with issues was the Document table.  Pretty central to a “document management” system.  Information was obtained from IT that a single drive in the SAN went bad in the night.  A new drive was in place and was working fine.  The partition that held the Batman database is configured for RAID Level 5 so a single drive failure shouldn’t have caused any trouble and yet, the database is corrupted.  They do hourly incremental backups here so the first thing done was to try a restore.  A restore of the most recent backup failed so they worked backwards until they hit a good point.  This successful restore was for a backup at 3AM – a full day behind.  This time also roughly corresponds with the time the SAN started to report the drive failure.  The plot thickens… I got my hands on the output from DBCC CHECKDB and noticed a pattern.  What’s sad is that nobody that should have noticed the pattern in the DBCC output did notice.  There was a rush to do things to try and recover the data before anybody really understood what was wrong with it in the first place.  Cooler heads must prevail in these circumstances and some investigation should be done and a plan of action laid out or you could end up making things worse[3].  DBCC CHECKDB also told us that: repair_allow_data_loss is the minimum repair level for the errors found by DBCC CHECKDB Yikes.  That means that the database is so messed up that you’re definitely going to lose some stuff when you repair it to get it back to a consistent state.  All the more reason to do a little more investigation into the problem.  Rescuing this database is preferable to having to export all of the data possible from this database into a new one.  This is a fifteen year old application with about seven hundred tables.  There are TRIGGERS everywhere not to mention the referential integrity constraints to deal with.  Only fourteen of the tables have an issue.  We have a good backup that is missing the last 24 hours of business which means we could have a “do-over” of yesterday but that’s not a very palatable option either. All of the affected tables had TEXT columns and all of the errors were about LOB data types and orphaned off-row data which basically means TEXT, IMAGE or NTEXT columns.  If we did a SELECT on an affected table and excluded those columns, we got all of the rows.  We exported that data into a separate database.  Things are looking up.  Working on a copy of the production database we then ran DBCC CHECKDB with REPAIR_ALLOW_DATA_LOSS and that “fixed” everything up.   The allow data loss option will delete the bad rows.  This isn’t too horrible as we have all of those rows minus the text fields from out earlier export.  Now I could LEFT JOIN to the exported data to find the missing rows and INSERT them minus the TEXT column data. We had the restored data from the good 3AM backup that we could now JOIN to and, with fingers crossed, recover the missing TEXT column information.  We got lucky in that all of the affected rows were old and in the end we didn’t lose anything.  :O  All of the row counts along the way worked out and it looks like we dodged a major bullet here. We’ve heard back from EMC and it turns out the SAN firmware that they were running here is apparently buggy.  This thing is only a couple of months old.  Grrr…. They dispatched a technician that night to come and update it .  That explains why RAID didn’t save us. All-in-all this could have been a lot worse.  Given the root cause here, they basically won the lottery in not losing anything. Here are a few links to some helpful posts on the SQL Server Engine blog.  I love the title of the first one: Which part of 'REPAIR_ALLOW_DATA_LOSS' isn't clear? CHECKDB (Part 8): Can repair fix everything? (in fact, read the whole series) Ta da! Emergency mode repair (we didn’t have to resort to this one thank goodness)   Dave Just because I can…   [1] Names have been changed to protect the guilty. [2] I'm Batman. [3] And if I'm the coolest head in the room, you've got even bigger problems...

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• Odd company release cycle: Go Distributed Source Control?

  - by MrLane

  sorry about this long post, but I think it is worth it! I have just started with a small .NET shop that operates quite a bit differently to other places that I have worked. Unlike any of my previous positions, the software written here is targetted at multiple customers and not every customer gets the latest release of the software at the same time. As such, there is no "current production version." When a customer does get an update, they also get all of the features added to he software since their last update, which could be a long time ago. The software is highly configurable and features can be turned on and off: so called "feature toggles." Release cycles are very tight here, in fact they are not on a shedule: when a feature is complete the software is deployed to the relevant customer. The team only last year moved from Visual Source Safe to Team Foundation Server. The problem is they still use TFS as if it were VSS and enforce Checkout locks on a single code branch. Whenever a bug fix gets put out into the field (even for a single customer) they simply build whatever is in TFS, test the bug was fixed and deploy to the customer! (Myself coming from a pharma and medical devices software background this is unbeliveable!). The result is that half baked dev code gets put into production without being even tested. Bugs are always slipping into release builds, but often a customer who just got a build will not see these bugs if they don't use the feature the bug is in. The director knows this is a problem as the company is starting to grow all of a sudden with some big clients coming on board and more smaller ones. I have been asked to look at source control options in order to eliminate deploying of buggy or unfinished code but to not sacrifice the somewhat asyncronous nature of the teams releases. I have used VSS, TFS, SVN and Bazaar in my career, but TFS is where most of my experience has been. Previously most teams I have worked with use a two or three branch solution of Dev-Test-Prod, where for a month developers work directly in Dev and then changes are merged to Test then Prod, or promoted "when its done" rather than on a fixed cycle. Automated builds were used, using either Cruise Control or Team Build. In my previous job Bazaar was used sitting on top of SVN: devs worked in their own small feature branches then pushed their changes to SVN (which was tied into TeamCity). This was nice in that it was easy to isolate changes and share them with other peoples branches. With both of these models there was a central dev and prod (and sometimes test) branch through which code was pushed (and labels were used to mark builds in prod from which releases were made...and these were made into branches for bug fixes to releases and merged back to dev). This doesn't really suit the way of working here, however: there is no order to when various features will be released, they get pushed when they are complete. With this requirement the "continuous integration" approach as I see it breaks down. To get a new feature out with continuous integration it has to be pushed via dev-test-prod and that will capture any unfinished work in dev. I am thinking that to overcome this we should go down a heavily feature branched model with NO dev-test-prod branches, rather the source should exist as a series of feature branches which when development work is complete are locked, tested, fixed, locked, tested and then released. Other feature branches can grab changes from other branches when they need/want, so eventually all changes get absorbed into everyone elses. This fits very much down a pure Bazaar model from what I experienced at my last job. As flexible as this sounds it just seems odd to not have a dev trunk or prod branch somewhere, and I am worried about branches forking never to re-integrate, or small late changes made that never get pulled across to other branches and developers complaining about merge disasters... What are peoples thoughts on this? A second final question: I am somewhat confused about the exact definition of distributed source control: some people seem to suggest it is about just not having a central repository like TFS or SVN, some say it is about being disconnected (SVN is 90% disconnected and TFS has a perfectly functional offline mode) and others say it is about Feature Branching and ease of merging between branches with no parent-child relationship (TFS also has baseless merging!). Perhaps this is a second question!

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• Five development tools I can't live without

  - by bconlon

  When applying to join Geeks with Blogs I had to specify the development tools I use every day. That got me thinking, it's taken a long time to whittle my tools of choice down to the selection I use, so it might be worth sharing. Before I begin, I appreciate we all have our preferred development tools, but these are the ones that work for me. Microsoft Visual Studio Microsoft Visual Studio has been my development tool of choice for more years than I care to remember. I first used this when it was Visual C++ 1.5 (hats off to those who started on 1.0) and by 2.2 it had everything I needed from a C++ IDE. Versions 4 and 5 followed and if I had to guess I would expect more Windows applications are written in VC++ 6 and VB6 than any other language. Then came the not so great versions Visual Studio .Net 2002 (7.0) and 2003 (7.1). If I'm honest I was still using v6. 2005 was better and 2008 was simply brilliant. Everything worked, the compiler was super fast and I was happy again...then came 2010...oh dear. 2010 is a big step backwards for me. It's not encouraging for my upcoming WPF exploits that 2010 is fronted in WPF technology, with the forever growing Find/Replace dialog, the issues with C++ intellisense, and the buggy debugger. That said it is still my tool of choice but I hope they sort the issue in SP1. I've tried other IDEs like Visual Age and Eclipse, but for me Visual Studio is the best. A really great tool. Liquid XML Studio XML development is a tricky business. The W3C standards are often difficult to get to the bottom of so it's great to have a graphical tool to help. I first used Liquid Technologies 5 or 6 years back when I needed to process XML data in C++. Their excellent XML Data Binding tool has an easy to use Wizard UI (as compared to Castor or JAXB command line tools) and allows you to generate code from an XML Schema. So instead of having to deal with untyped nodes like with a DOM parser, instead you get an Object Model providing a custom API in C++, C#, VB etc. More recently they developed a graphical XML IDE with XML Editor, XSLT, XQuery debugger and other XML tools. So now I can develop an XML Schema graphically, click a button to generate a Sample XML document, and click another button to run the Wizard to generate code including a Sample Application that will then load my Sample XML document into the generated object model. This is a very cool toolset. Note: XML Data Binding is nothing to do with WPF Data Binding, but I hope to cover both in more detail another time. .Net Reflector Note: I've just noticed that starting form the end of February 2011 this will no longer be a free tool !! .Net Reflector turns .Net byte code back into C# source code. But how can it work this magic? Well the clue is in the name, it uses reflection to inspect a compiled .Net assembly. The assembly is compiled to byte code, it doesn't get compiled to native machine code until its needed using a just-in-time (JIT) compiler. The byte code still has all of the information needed to see classes, variables. methods and properties, so reflector gathers this information and puts it in a handy tree. I have used .Net Reflector for years in order to understand what the .Net Framework is doing as it sometimes has undocumented, quirky features. This really has been invaluable in certain instances and I cannot praise enough kudos on the original developer Lutz Roeder. Smart Assembly In order to stop nosy geeks looking at our code using a tool like .Net Reflector, we need to obfuscate (mess up) the byte code. Smart Assembly is a tool that does this. Again I have used this for a long time. It is very quick and easy to use. Another excellent tool. Coincidentally, .Net Reflector and Smart Assembly are now both owned by Red Gate. Again kudos goes to the original developer Jean-Sebastien Lange. TortoiseSVN SVN (Apache Subversion) is a Source Control System developed as an open source project. TortoiseSVN is a graphical UI wrapper over SVN that hooks into Windows Explorer to enable files to be Updated, Committed, Merged etc. from the right click menu. This is an essential tool for keeping my hard work safe! Many years ago I used Microsoft Source Safe and I disliked CVS type systems. But TortoiseSVN is simply the best source control tool I have ever used. --- So there you have it, my top 5 development tools that I use (nearly) every day and have helped to make my working life a little easier. I'm sure there are other great tools that I wish I used but have never heard of, but if you have not used any of the above, I would suggest you check them out as they are all very, very cool products. #

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• JustCode Provides Reflector Alternative

  - by Joe Mayo

  If you've been a loyal Reflector user, you've probably been exposed to the debacle surrounding RedGate's decision to no longer offer a free version.  Since then, the race has begun for a replacement with a provider that would stand by their promises to the community.  Mono has an ongoing free alternative, which has been available for a long time.  However, other vendors are stepping up to the plate, with their own offerings. If Not Reflector, Then What? One of these vendors is Telerik.  In their recent Q1 2011 release of JustCode, Telerik offers a decompilation utility rivaling what we've become accustomed to in Reflector.  Not only does Telerik offer a usable replacement, but they've (in my opinion), produced a product that integrates more naturally with visual Studio than any other product ever has.  Telerik's decompilation process is so easy that the accompanying demo in this post is blindingly short (except for the presence of verbose narrative). If you want to follow along with this demo, you'll need to have Telerik JustCode installed.  If you don't have JustCode yet, you can buy it or download a trial at the Telerik Web site . A Tall Tale; Prove It! With JustCode, you can view code in the .NET Framework or any other 3rd party library (that isn't well obfuscated).  This demo depends on LINQ to Twitter, which you can download from CodePlex.com and create a reference or install the package online as described in my previous post on NuGet.  Regardless of the method, you'll have a project with a reference to LINQ to Twitter.  Use a Console Project if you want to follow along with this demo. Note:  If you've created a Console project, remember to ensure that the Target Framework is set to .NET Framework 4.  The default is .NET Framework 4 Client Profile, which doesn't work with LINQ to Twitter.  You can check by double-clicking the Properties folder on the project and inspecting the Target Framework setting. Next, you'll need to add some code to your program that you want to inspect. Here, I add code to instantiate a TwitterContext, which is like a LINQ to SQL DataContext, but works with Twitter: var l2tCtx = new TwitterContext(); If you're following along add the code above to the Main method, which will look similar to this: using LinqToTwitter; namespace NuGetInstall { class Program { static void Main(string[] args) { var l2tCtx = new TwitterContext(); } } } The code above doesn't really do anything, but it does give something that I can show and demonstrate how JustCode decompilation works. Once the code is in place, click on TwitterContext and press the F12 (Go to Definition) key.  As expected, Visual Studio opens a metadata file with prototypes for the TwitterContext class.  Here's the result: Opening a metadata file is the normal way that Visual Studio works when navigating to the definition of a type where you don't have the code.  The scenario with TwitterContext happens because you don't have the source code to the file.  Visual Studio has always done this and you can experiment by selecting any .NET type, i.e. a string type, and observing that Visual Studio opens a metadata file for the .NET String type. The point I'm making here is that JustCode works the way Visual Studio works and you'll see how this can make your job easier. In the previous figure, you only saw prototypes associated with the code. i.e. Notice that the default constructor is empty.  Again, this is normal because Visual Studio doesn't have the ability to decompile code.  However, that's the purpose of this post; showing you how JustCode fills that gap. To decompile code, right click on TwitterContext in the metadata file and select JustCode Navigate -> Decompile from the context menu.  The shortcut keys are Ctrl+1.  After a brief pause, accompanied by a progress window, you'll see the metadata expand into full decompiled code. Notice below how the default constructor now has code as opposed to the empty member prototype in the original metadata: And Why is This So Different? Again, the big deal is that Telerik JustCode decompilation works in harmony with the way that Visual Studio works.  The navigate to functionality already exists and you can use that, along with a simple context menu option (or shortcut key) to transform prototypes into decompiled code. Telerik is filling the the Reflector/Red Gate gap by providing a supported alternative to decompiling code.  Many people, including myself, used Reflector to decompile code when we were stuck with buggy libraries or insufficient documentation.  Now we have an alternative that's officially supported by a company with an excellent track record for customer (developer) service, Telerik.  Not only that, JustCode has several other IDE productivity tools that make the deal even sweeter. Joe

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• Solaris 11.2: Functional Deprecation

  - by alanc

  In Solaris 11.1, I updated the system headers to enable use of several attributes on functions, including noreturn and printf format, to give compilers and static analyzers more information about how they are used to give better warnings when building code. In Solaris 11.2, I've gone back in and added one more attribute to a number of functions in the system headers: __attribute__((__deprecated__)). This is used to warn people building software that they’re using function calls we recommend no longer be used. While in many cases the Solaris Binary Compatibility Guarantee means we won't ever remove these functions from the system libraries, we still want to discourage their use. I made passes through both the POSIX and C standards, and some of the Solaris architecture review cases to come up with an initial list which the Solaris architecture review committee accepted to start with. This set is by no means a complete list of Obsolete function interfaces, but should be a reasonable start at functions that are well documented as deprecated and seem useful to warn developers away from. More functions may be flagged in the future as they get deprecated, or if further passes are made through our existing deprecated functions to flag more of them. Header Interface Deprecated by Alternative Documented in <door.h> door_cred(3C) PSARC/2002/188 door_ucred(3C) door_cred(3C) <kvm.h> kvm_read(3KVM), kvm_write(3KVM) PSARC/1995/186 Functions on kvm_kread(3KVM) man page kvm_read(3KVM) <stdio.h> gets(3C) ISO C99 TC3 (Removed in ISO C11), POSIX:2008/XPG7/Unix08 fgets(3C) gets(3C) man page, and just about every gets(3C) reference online from the past 25 years, since the Morris worm proved bad things happen when it’s used. <unistd.h> vfork(2) PSARC/2004/760, POSIX:2001/XPG6/Unix03 (Removed in POSIX:2008/XPG7/Unix08) posix_spawn(3C) vfork(2) man page. <utmp.h> All functions from getutent(3C) man page PSARC/1999/103 utmpx functions from getutentx(3C) man page getutent(3C) man page <varargs.h> varargs.h version of va_list typedef ANSI/ISO C89 standard <stdarg.h> varargs(3EXT) <volmgt.h> All functions PSARC/2005/672 hal(5) API volmgt_check(3VOLMGT), etc. <sys/nvpair.h> nvlist_add_boolean(3NVPAIR), nvlist_lookup_boolean(3NVPAIR) PSARC/2003/587 nvlist_add_boolean_value, nvlist_lookup_boolean_value nvlist_add_boolean(3NVPAIR) & (9F), nvlist_lookup_boolean(3NVPAIR) & (9F). <sys/processor.h> gethomelgroup(3C) PSARC/2003/034 lgrp_home(3LGRP) gethomelgroup(3C) <sys/stat_impl.h> _fxstat, _xstat, _lxstat, _xmknod PSARC/2009/657 stat(2) old functions are undocumented remains of SVR3/COFF compatibility support If the above table is cut off when viewing in the blog, try viewing this standalone copy of the table. To See or Not To See To see these warnings, you will need to be building with either gcc (versions 3.4, 4.5, 4.7, & 4.8 are available in the 11.2 package repo), or with Oracle Solaris Studio 12.4 or later (which like Solaris 11.2, is currently in beta testing). For instance, take this oversimplified (and obviously buggy) implementation of the cat command: #include <stdio.h> int main(int argc, char **argv) { char buf[80]; while (gets(buf) != NULL) puts(buf); return 0; } Compiling it with the Studio 12.4 beta compiler will produce warnings such as: % cc -V cc: Sun C 5.13 SunOS_i386 Beta 2014/03/11 % cc gets_test.c "gets_test.c", line 6: warning: "gets" is deprecated, declared in : "/usr/include/iso/stdio_iso.h", line 221 The exact warning given varies by compilers, and the compilers also have a variety of flags to either raise the warnings to errors, or silence them. Of couse, the exact form of the output is Not An Interface that can be relied on for automated parsing, just shown for example. gets(3C) is actually a special case — as noted above, it is no longer part of the C Standard Library in the C11 standard, so when compiling in C11 mode (i.e. when __STDC_VERSION__ >= 201112L), the <stdio.h> header will not provide a prototype for it, causing the compiler to complain it is unknown: % gcc -std=c11 gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: warning: implicit declaration of function ‘gets’ [-Wimplicit-function-declaration] while (gets(buf) != NULL) ^ The gets(3C) function of course is still in libc, so if you ignore the error or provide your own prototype, you can still build code that calls it, you just have to acknowledge you’re taking on the risk of doing so yourself. Solaris Studio 12.4 Beta % cc gets_test.c "gets_test.c", line 6: warning: "gets" is deprecated, declared in : "/usr/include/iso/stdio_iso.h", line 221 % cc -errwarn=E_DEPRECATED_ATT gets_test.c "gets_test.c", line 6: "gets" is deprecated, declared in : "/usr/include/iso/stdio_iso.h", line 221 cc: acomp failed for gets_test.c This warning is silenced in the 12.4 beta by cc -erroff=E_DEPRECATED_ATT No warning is currently issued by Studio 12.3 & earler releases. gcc 3.4.3 % /usr/sfw/bin/gcc gets_test.c gets_test.c: In function `main': gets_test.c:6: warning: `gets' is deprecated (declared at /usr/include/iso/stdio_iso.h:221) Warning is completely silenced with gcc -Wno-deprecated-declarations gcc 4.7.3 % /usr/gcc/4.7/bin/gcc gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: warning: ‘gets’ is deprecated (declared at /usr/include/iso/stdio_iso.h:221) [-Wdeprecated-declarations] % /usr/gcc/4.7/bin/gcc -Werror=deprecated-declarations gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: error: ‘gets’ is deprecated (declared at /usr/include/iso/stdio_iso.h:221) [-Werror=deprecated-declarations] cc1: some warnings being treated as errors Warning is completely silenced with gcc -Wno-deprecated-declarations gcc 4.8.2 % /usr/bin/gcc gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: warning: ‘gets’ is deprecated (declared at /usr/include/iso/stdio_iso.h:221) [-Wdeprecated-declarations] while (gets(buf) != NULL) ^ % /usr/bin/gcc -Werror=deprecated-declarations gets_test.c gets_test.c: In function ‘main’: gets_test.c:6:5: error: ‘gets’ is deprecated (declared at /usr/include/iso/stdio_iso.h:221) [-Werror=deprecated-declarations] while (gets(buf) != NULL) ^ cc1: some warnings being treated as errors Warning is completely silenced with gcc -Wno-deprecated-declarations

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• How do I dig myself out of this DEEP hole? [closed]

  - by user74847

  I may be a bit bias in the way i word this but any opinions and suggestions are welcome. I should start by saying i have a MSc in CS and a degree in new media +6 years expereince and im probably around a middleweight developer. I started a web development company with my friend from uni a year ago, there was a 4 month gap in the middle where i went miles away work on a big project. Ive since returned and picked up where we left off. A year on though i find im still staying up til 5am and getting up at 9 sometimes 2-3 days without sleep. While i was away i was working 9-5 and struggling to keep up with doing stuff for my clients 8 hours ahead, after work, so things stagnated. We currently have about 12 active projects, with one other part time developer and a full time freelancer who is dealing with one of our major projects. I am solely responsible for concurrently developing 2 big sites similar to gumtree in functionality, at the same time as about 5-6+ small WordPress based 5-10page sites. a lot of the content isnt in yet or the client is delaying so i chop and change project every other day which does my head in. Is it reasonable to expect myself to remember the intricate details of each project when i come back to it a week later? and remember the details of a task which hasnt been written down? my business partner seems to think so. or am i just forgetful? Im particularly bad at estimating timescales which doesnt help, added to that a lot of the technologies im am using are new to me (a magento site took weeks to theme rather than days and was full of bugs, even after 1000's of google searches and hours reading forums) im still trying to learn and find the best CMS for us to use and getting my head around the likes of Bootstrap and jquery, Cpanel / Linux (we just got a blank vps for me to set up with no experience) even installing an SSL certificate caused everyone's mail clients to go down which was more stress for me to sort out. I find the pressure of the workload and timescales and trying to learn this stuff so fast is beginning to turn me against my career path. The fact that i never seem to get anything done really winds up my business partner and iv come to associate him with the stress and pain of the whole situation especially when I get berated or a look that says "oh you retard" when I forget something. Even today i spent hours learning how a particular themeforest theme worked with wordpress and how i could twist it to work for our partiuclar needs, on the surface had done no work, that triggered a 30 minute tirade of anger and stress and questioning what i had done from my business partner. had i taken too long to work on that? shoudl i have done it in 2 hours instead of 6? i told him i would take 2 hours. i was wrong. I feel like im running myself into the ground. My sleeping pattern has got so bad that when im working im half asleep and making mistakes, my eyes are constantly purple underneath, i literally fall asleep at my desk, its affecting my social life too, ive not slept more than lightly for the last year and grind through impossible code puzzles in my half sleep wich keeps me awake, when im already exhausted. plus the work is rushed and buggy when it does get done so drags on into the next project. I also procrastinate quite badly, pacing the livingroom, looking out the window when Im alone for three days straight in the flat and start to get cabin fever which means i do even less work and the negative feedback loop continues. I get told im the only one with the problem when i say that i cant work from home any more, and examples of other freelancers get brought up. an office wouldnt bring any extra cash in to the company but im convinced having that moving more than 2 meters away from my bed to go to "work" would get me working, at the moment i feel guilty like i should be working 24-7. It is important that we do all this work to raise enough cash to get our business to the next level but every month still feels like a struggle to pay the rent (there is about £20K coming in by Jan) and i have to borrow money from friends often to buy food or get a taxi to a meeting, so it is vital the money keeps coming in. (im also 20 mins late for nearly all meetings but thats a different issue) have you experienced anything similar? how can i deal with the issues ive raised? is it realistic to develop 10 sites at once? how can i improve my relationship with my business partner? do you struggle to work at home? how do you deal with that? i think if i dont get my life on track by feb i will seriously consider giving it all up, but that seems like such a waste. any ideas!!? i need help! Thanks.

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• Stack overflow in compojure web project

  - by Anders Rune Jensen

  Hi I've been playing around with clojure and have been using it to build a simple little audio player. The strange thing is that sometimes, maybe one out of twenty, when contacting the server I will get the following error: 2010-04-20 15:33:20.963::WARN: Error for /control java.lang.StackOverflowError at clojure.lang.RT.seq(RT.java:440) at clojure.core$seq__4245.invoke(core.clj:105) at clojure.core$filter__5084$fn__5086.invoke(core.clj:1794) at clojure.lang.LazySeq.sval(LazySeq.java:42) at clojure.lang.LazySeq.seq(LazySeq.java:56) at clojure.lang.RT.seq(RT.java:440) at clojure.core$seq__4245.invoke(core.clj:105) at clojure.core$filter__5084$fn__5086.invoke(core.clj:1794) at clojure.lang.LazySeq.sval(LazySeq.java:42) at clojure.lang.LazySeq.seq(LazySeq.java:56) at clojure.lang.RT.seq(RT.java:440) at clojure.core$seq__4245.invoke(core.clj:105) at clojure.core$filter__5084$fn__5086.invoke(core.clj:1794) at clojure.lang.LazySeq.sval(LazySeq.java:42) at clojure.lang.LazySeq.seq(LazySeq.java:56) at clojure.lang.RT.seq(RT.java:440) at clojure.core$seq__4245.invoke(core.clj:105) at clojure.core$filter__5084$fn__5086.invoke(core.clj:1794) at clojure.lang.LazySeq.sval(LazySeq.java:42) at clojure.lang.LazySeq.seq(LazySeq.java:56) at clojure.lang.RT.seq(RT.java:440) ... If I do it right after again it always works. So it appears to be related to timing or something. The code in question is: (defn add-track [t] (common/ref-add tracks t)) (defn add-collection [coll] (doseq [track coll] (add-track track))) and (defn ref-add [ref value] (dosync (ref-set ref (conj @ref value)))) where coll is extracted from this function: (defn tracks-by-album [album] (sort sort-tracks (filter #(= (:album %) album) @tracks))) which uses: (defn get-album-from-track [track] (seq/find-first #(= (:album track) (:name %)) @albums)) (defn sort-tracks [track1 track2] (cond (= (:album track1) (:album track2)) (cond (and (:album-track track1) (:album-track track2)) (< (:album-track track1) (:album-track track2)) :else 0) :else (> (:year (get-album-from-track track1)) (:year (get-album-from-track track2))))) it gets called more or less directly from the request I get in: (when-handle-command cmd params (audio/tracks-by-album decoded-name)) (defn when-handle-command [cmd params data] (println (str "handling command:" cmd)) ....) I never get the handling command in my log, so it must die when it does the tracks-by-album. so it does appear to be the tracks-by-album function from the stack trace. I just don't see why it sometimes works and sometimes doesn't. I say that it's tracks-by-album because it's the only function (including it's children) that does filter, as can be seen in the trace. All the source code is available at: http://code.google.com/p/mucomp/. It's my little hobby project to learn clojure and so far it's quite buggy (this is just one bug :)) so I havn't really liked to tell too many people about it yet :)

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• Google Streetview under V3 Code having hiccups and delays

  - by jeffkee

  http://new.brocksmeaton.com/showlisting.php/196/-7210-Arbutus-Place-Whytecliff-West-Vancouver-west-vancouver-real-estate The really odd thing is I had this working yesterday and today it's not working. I'm using jQuery UI to switch the tabs on the location map/street view module. I've recently upgraded the Google Maps code as well as the Google Streetview code to version 3. So when I open it in Firefox, with Firebug on, as soon as I switch to the Streetview tab, the navigation and zoom in out controls show, but nothing shows.. and then when I try to drag the map around, it does not move around, but instead, causes errors in Firebug: "too much recursion". So it causes the whole browser to become buggy, slows down, and the errors happen, and nothing shows on the streetview pane. Most of the map loading code is located in inline Javascript on the page itself. Some of the code is under showlisting.js <script type="text/javascript" src="/js/showlisting.js"></script> <script type="text/javascript"> // Call this function when the page has been loaded function loadmap() { var latlng = new google.maps.LatLng(49.374918567425475, -123.28996885871596); var myOptions = { zoom: 14, center: latlng, mapTypeId: google.maps.MapTypeId.ROADMAP }; var map = new google.maps.Map(document.getElementById('listingmap'), myOptions); var listingicon = '/images/activehouse.png'; var infowindow = new google.maps.InfoWindow(); homemarker = new google.maps.Marker({position: latlng, map: map, icon: listingicon}); google.maps.event.addListener(homemarker, 'click', function() { infowindow.setContent('<div style="height:80px; width:250px; color:#333;"><p>7210 Arbutus Place<br />Whytecliff, West Vancouver</div>') infowindow.open(map,homemarker); }); } function loadpano() { var latlng = new google.maps.LatLng(49.374918567425475, -123.28996885871596); $('#listingpanorama').slideDown(500, function() { var panoramaOptions = { addressControl:false, position: latlng, pov: { heading: 34, pitch: 30, zoom: 1 } }; var panorama = new google.maps.StreetViewPanorama(document.getElementById('listingpanorama'), panoramaOptions); }); return false; } </script> My old one under GOogle API Version 2 is here FYI if you want to take a look at it: http://demo.brixwork.com/master/showlisting.php/63/1701-388-Drake-Street-False-Creek-North-Vancouver-

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• Subroutine & GoTo design

  - by sub

  I have a strange question concerning subroutines: As I'm creating a minimal language and I don't want to add high-level loops like while or for I was planning on just adding gotos to keep it Turing-Complete. Now I thought, eww - gotos - I wouldn't want to program in that language if I had to use gotos so often. So I thought about adding subroutines instead. I see the difference as the following: gotos Go to (captain obvious) a previously defined point and continue executing the program from there. Leads to hardly understandable and buggy code, I think that's a fact. subroutines Similiar: You define their starting point somewhere, as you call them the program jumps there - but the subroutine can go back to the point it was called from with return. Okay. Why didn't I just add the more function-like, nice looking subroutines? Because: In order to make return work if I call subroutines from within subroutines from within other subroutines, I'd have to use a stack containing the point where the currently running subroutine came from at top. That would then mean that I would, if I create loops using the subroutines, end up with an extremely memory-eating, overflowing stack with return locations. Not good. Don't think of my subroutines as functions. They are just gotos that return to the point they were called from, they don't actually give back values like the return x; statement in nearly all today's languages. Now to my actual questions: How can I solve the above problem with the stack overflow on loops with subroutines? Do I have to add a separate goto language construct without the return option? Assembler doesn't have loops but as I have seen myJumpPoint:, jnz, jz, retn. That means to me that there must also be a stack containing all the return locations. Am I right with that? What about long running loops then? Don't they overflow the stack/eat memory then? Am I getting the retn symbol in assembler totally wrong? If yes, please explain it to me.

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• What's the best way to do base36 arithmetic in perl?

  - by DVK

  What's the best way to do base36 arithmetic in Perl? To be more specific, I need to be able to do the following: Operate on positive N-digit numbers in base 36 (e.g. digits are 0-9 A-Z) N is finite, say 9 Provide basic arithmetic, at the very least the following 3: Addition (A+B) Subtraction (A-B) Whole division, e.g. floor(A/B). Strictly speaking, I don't really need a base10 conversion ability - the numbers will 100% of time be in base36. So I'm quite OK if the solution does NOT implement conversion from base36 back to base10 and vice versa. I don't much care whether the solution is brute-force "convert to base 10 and back" or converting to binary, or some more elegant approach "natively" performing baseN operations (as stated above, to/from base10 conversion is not a requirement). My only 3 considerations are: It fits the minimum specifications above It's "standard". Currently we're using and old homegrown module based on base10 conversion done by hand that is buggy and sucks. I'd much rather replace that with some commonly used CPAN solution instead of re-writing my own bicycle from scratch, but I'm perfectly capable of building it if no better standard possibility exists. It must be fast-ish (though not lightning fast). Something that takes 1 second to sum up 2 9-digit base36 numbers is worse than anything I can roll on my own :) P.S. Just to provide some context in case people decide to solve my XY problem for me in addition to answering the technical question above :) We have a fairly large tree (stored in DB as a bunch of edges), and we need to superimpose order on a subset of that tree. The tree dimentions are big both depth- and breadth- wise. The tree is VERY actively updated (inserts and deletes and branch moves). This is currently done by having a second table with 3 columns: parent_vertex, child_vertex, local_order, where local_order is an 9-character string built of A-Z0-9 (e.g. base 36 number). Additional considerations: It is required that the local order is unique per child (and obviously unique per parent), Any complete re-ordering of a parent is somewhat expensive, and thus the implementation is to try and assign - for a parent with X children - the orders which are somewhat evenly distributed between 0 and 36**10-1, so that almost no tree inserts result in a full re-ordering.

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• "Emulating" Application.Run using Application.DoEvents

  - by Luca

  I'm getting in trouble. I'm trying to emulate the call Application.Run using Application.DoEvents... this sounds bad, and then I accept also alternative solutions to my question... I have to handle a message pump like Application.Run does, but I need to execute code before and after the message handling. Here is the main significant snippet of code. // Create barrier (multiple kernels synchronization) sKernelBarrier = new KernelBarrier(sKernels.Count); foreach (RenderKernel k in sKernels) { // Create rendering contexts (one for each kernel) k.CreateRenderContext(); // Start render kernel kernels k.mThread = new Thread(RenderKernelMain); k.mThread.Start(k); } while (sKernelBarrier.KernelCount > 0) { // Wait untill all kernel loops has finished sKernelBarrier.WaitKernelBarrier(); // Do application events Application.DoEvents(); // Execute shared context services foreach (RenderKernelContextService s in sContextServices) s.Execute(sSharedContext); // Next kernel render loop sKernelBarrier.ReleaseKernelBarrier(); } This snippet of code is execute by the Main routine. Pratically I have a list of Kernel classes, which runs in separate threads, these threads handle a Form for rendering in OpenGL. I need to synchronize all the Kernel threads using a barrier, and this work perfectly. Of course, I need to handle Form messages in the main thread (Main routine), for every Form created, and indeed I call Application.DoEvents() to do the job. Now I have to modify the snippet above to have a common Form (simple dialog box) without consuming the 100% of CPU calling Application.DoEvents(), as Application.Run does. The goal should be to have the snippet above handle messages when arrives, and issue a rendering (releasing the barrier) only when necessary, without trying to get the maximum FPS; there should be the possibility to switch to a strict loop to render as much as possible. How could it be possible? Note: the snippet above must be executed in the Main routine, since the OpenGL context is created on the main thread. Moving the snippet in a separated thread and calling Application.Run is quite unstable and buggy...

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• Silverlight with MVVM Inheritance: ModelView and View matching the Model

  - by moonground.de

  Hello Stackoverflowers! :) Today I have a special question on Silverlight (4 RC) MVVM and inheritance concepts and looking for a best practice solution... I think that i understand the basic idea and concepts behind MVVM. My Model doesn't know anything about the ViewModel as the ViewModel itself doesn't know about the View. The ViewModel knows the Model and the Views know the ViewModels. Imagine the following basic (example) scenario (I'm trying to keep anything short and simple): My Model contains a ProductBase class with a few basic properties, a SimpleProduct : ProductBase adding a few more Properties and ExtendedProduct : ProductBase adding another properties. According to this Model I have several ViewModels, most essential SimpleProductViewModel : ViewModelBase and ExtendedProductViewModel : ViewModelBase. Last but not least, according Views SimpleProductView and ExtendedProductView. In future, I might add many product types (and matching Views + VMs). 1. How do i know which ViewModel to create when receiving a Model collection? After calling my data provider method, it will finally end up having a List<ProductBase>. It containts, for example, one SimpleProduct and two ExtendedProducts. How can I transform the results to an ObservableCollection<ViewModelBase> having the proper ViewModel types (one SimpleProductViewModel and two ExtendedProductViewModels) in it? I might check for Model type and construct the ViewModel accordingly, i.e. foreach(ProductBase currentProductBase in resultList) if (currentProductBase is SimpleProduct) viewModels.Add( new SimpleProductViewModel((SimpleProduct)currentProductBase)); else if (currentProductBase is ExtendedProduct) viewModels.Add( new ExtendedProductViewModels((ExtendedProduct)currentProductBase)); ... } ...but I consider this very bad practice as this code doesn't follow the object oriented design. The other way round, providing abstract Factory methods would reduce the code to: foreach(ProductBase currentProductBase in resultList) viewModels.Add(currentProductBase.CreateViewModel()) and would be perfectly extensible but since the Model doesn't know the ViewModels, that's not possible. I might bring interfaces into game here, but I haven't seen such approach proven yet. 2. How do i know which View to display when selecting a ViewModel? This is pretty the same problem, but on a higher level. Ended up finally having the desired ObservableCollection<ViewModelBase> collection would require the main view to choose a matching View for the ViewModel. In WPF, there is a DataTemplate concept which can supply a View upon a defined DataType. Unfortunately, this doesn't work in Silverlight and the only replacement I've found was the ResourceSelector of the SLExtensions toolkit which is buggy and not satisfying. Beside that, all problems from Question 1 apply as well. Do you have some hints or even a solution for the problems I describe, which you hopefully can understand from my explanation? Thank you in advance! Thomas

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• Clickin issue in Flash and XML

  - by ortho

  Hi, I have the php backend that displays an xml page with data for flash consuming. Flash takes it and creates a textfields dynamicaly based on this information. I have a few items in menu on top and when I click one of them, data is taken from php and everything is displayed in scroll in flash. The problem is that if I click too fast between menu items, then I get buggy layout. The text (only the text) is becoming part of the layout and is displayed no metter what item in menu I am currently in and only refreshing the page helps. var myXML:XML = new XML(); myXML.ignoreWhite=true; myXML.load("/getBud1.php"); myXML.onLoad = function(success){ if (success){ var myNode = this.firstChild.childNodes; var myTxt:Array = Array(0); for (var i:Number = 0; i<myNode.length; i++) { myTxt[i] = "text"+i+"content"; createTextField(myTxt[i],i+1,65,3.5,150, 20); var pole = eval(myTxt[i]); pole.embedFonts = true; var styl:TextFormat = new TextFormat(); styl.font = "ArialFont"; pole.setNewTextFormat(styl); pole.text = String(myNode[i].childNodes[1].firstChild.nodeValue); pole.wordWrap = true; pole.autoSize = "left"; if(i > 0) { var a:Number = eval(myTxt[i-1])._height + eval(myTxt[i-1])._y + 3; pole._y = a; } attachMovie("kropka2", "test"+i+"th", i+1000); eval("test"+i+"th")._y = pole._y + 5; eval("test"+i+"th")._x = 52; } } } I tried to load the info and ceate text fields from top frame and then refer to correct place by instance names string e.g. budData.dataHolder.holder.createTextField , but then when I change between items in menu the text dissapears completely untill I refresh the page. Please help

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• What is a good platform for building a game framework targetting both web and native languages?

  - by fuzzyTew

  I would like to develop (or find, if one is already in development) a framework with support for accelerated graphics and sound built on a system flexible enough to compile to the following: native ppc/x86/x86_64/arm binaries or a language which compiles to them javascript actionscript bytecode or a language which compiles to it (actionscript 3, haxe) optionally java I imagine, for example, creating an API where I can open windows and make OpenGL-like calls and the framework maps this in a relatively efficient manner to either WebGL with a canvas object, 3d graphics in Flash, OpenGL ES 2 with EGL, or desktop OpenGL in an X11, Windows, or Cocoa window. I have so far looked into these avenues: Building the game library in haXe Pros: Targets exist for php, javascript, actionscript bytecode, c++ High level, object oriented language Cons: No support for finally{} blocks or destructors, making resource cleanup difficult C++ target does not allow room for producing highly optimized libraries -- the foreign function interface requires all primitive types be boxed in a wrapper object, as if writing bindings for a scripting language; these feel unideal for real-time graphics and audio, especially exporting low-level functions. Doesn't seem quite yet mature Using the C preprocessor to create a translator, writing programs entirely with macros Pros: CPP is widespread and simple to use Cons: This is an arduous task and probably the wrong tool for the job CPP implementations differ widely in support for features (e.g. xcode cpp has no variadic macros despite claiming C99 compliance) There is little-to-no room for optimization in this route Using llvm's support for multiple backends to target c/c++ to web languages Pros: Can code in c/c++ LLVM is a very mature highly optimizing compiler performing e.g. global inlining Targets exist for actionscript (alchemy) and javascript (emscripten) Cons: Actionscript target is closed source, unmaintained, and buggy. Javascript targets do not use features of HTML5 for appropriate optimization (e.g. linear memory with typed arrays) and are immature An LLVM target must convert from low-level bytecode, so high-level constructs are lost and bloated unreadable code is created from translating individual instructions, which may be more difficult for an unprepared JIT to optimize. "jump" instructions cause problems for languages with no "goto" statements. Using libclang to write a translator from C/C++ to web languages Pros: A beautiful parsing library providing easy access to the code structure Can code in C/C++ Has sponsored developer effort from Apple Cons: Incomplete; current feature set targets IDEs. Basic operators are unexposed and must be manually parsed from the returned AST element to be identified. Translating code prior to compilation may forgo optimizations assumed in c/c++ such as inlining. Creating new code generators for clang to translate into web languages Pros: Can code in C/C++ as libclang Cons: There is no API; code structure is unstable A much larger job than using libclang; the innards of clang are complex Building the game library in Common Lisp Pros: Flexible, ancient, well-developed language Extensive introspection should ease writing translators Translators exist for at least javascript Cons: Unfamiliar language No standardized library functions, widely varying implementations Which of these avenues should I pursue? Do you know of any others, or any systems that might be useful? Does a general project like this exist somewhere already? Thank you for any input.

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• Strange behavior with gcc inline assembly

  - by Chris

  When inlining assembly in gcc, I find myself regularly having to add empty asm blocks in order to keep variables alive in earlier blocks, for example: asm("rcr $1,%[borrow];" "movq 0(%[b_],%[i],8),%%rax;" "adcq %%rax,0(%[r_top],%[i],8);" "rcl $1,%[borrow];" : [borrow]"+r"(borrow) : [i]"r"(i),[b_]"r"(b_.data),[r_top]"r"(r_top.data) : "%rax","%rdx"); asm("" : : "r"(borrow) : ); // work-around to keep borrow alive ... Another example of weirdness is that the code below works great without optimizations, but with -O3 it seg-faults: ulong carry = 0,hi = 0,qh = s.data[1],ql = s.data[0]; asm("movq 0(%[b]),%%rax;" "mulq %[ql];" "movq %%rax,0(%[sb]);" "movq %%rdx,%[hi];" : [hi]"=r"(hi) : [ql]"r"(ql),[b]"r"(b.data),[sb]"r"(sb.data) : "%rax","%rdx","memory"); for (long i = 1; i < b.size; i++) { asm("movq 0(%[b],%[i],8),%%rax;" "mulq %[ql];" "xorq %%r10,%%r10;" "addq %%rax,%[hi];" "adcq %%rdx,%[carry];" "adcq $0,%%r10;" "movq -8(%[b],%[i],8),%%rax;" "mulq %[qh];" "addq %%rax,%[hi];" "adcq %%rdx,%[carry];" "adcq $0,%%r10;" "movq %[hi],0(%[sb],%[i],8);" "movq %[carry],%[hi];" "movq %%r10,%[carry];" : [carry]"+r"(carry),[hi]"+r"(hi) : [i]"r"(i),[ql]"r"(ql),[qh]"r"(qh),[b]"r"(b.data),[sb]"r"(sb.data) : "%rax","%rdx","%r10","memory"); } asm("movq -8(%[b],%[i],8),%%rax;" "mulq %[qh];" "addq %%rax,%[hi];" "adcq %%rdx,%[carry];" "movq %[hi],0(%[sb],%[i],8);" "movq %[carry],8(%[sb],%[i],8);" : [hi]"+r"(hi),[carry]"+r"(carry) : [i]"r"(long(b.size)),[qh]"r"(qh),[b]"r"(b.data),[sb]"r"(sb.data) : "%rax","%rdx","memory"); I think it has to do with the fact that it's using so many registers. Is there something I'm missing here or is the register allocation just really buggy with gcc inline assembly?

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