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• Swap partition not recognized (The disk drive with UUID=... is not ready yet or not present)

  - by ladaghini

  I think I had an encrypted swap partition, because I chose to encrypt my home directory during the installation. I believe that's what the line with /dev/mapper/cryptswap1 ... in my /etc/fstab is all about. I did something to bork my swap because on the next boot, I got a message (paraphrased): The disk drive for /dev/mapper/cryptswap1 is not ready yet or not present. Wait to continue. Press S to skip or M to manually recover. (As a side note, pressing S or M seemed to do nothing different from just waiting.) Here's what I've tried: This tutorial on how to fix the swap partition not mounting. However, in the above, the mkswap command fails because the device is busy. So I booted from a live USB, ran GParted to reformat the swap partition (which showed up as an unknown fs type), and chrooted into the broken system to try that tutorial again. I also adjusted /etc/initramfs-tools/conf.d/resume and /etc/fstab to reflect the new UUID generated from formatting the partition as a swap. That still didn't work; instead of /dev/mapper/cryptswap1 not present, "The disk drive with UUID=[swap partition's UUID] is not ready yet or not present..." So I decided to start afresh as though I never had created a swap partition in the first place. From the Live USB, I deleted the swap partition altogether (which, again showed up in GParted as an unknown fs type), removed the swap and cryptswap entries in /etc/fstab as well as removed /etc/initramfs-tools/conf.d/resume and /etc/crypttab. At this point the main system shouldn't be considered broken because there is no swap partition and no instructions to mount one, right? I didn't get any errors during startup. I followed the same instructions to create and encrypt the swap partition, starting with creating a partition for the swap, though I think fdisk said a reboot was necessary to see changes. I was confident the 3rd process above would work, but the problem yet persists. Some relevant info (/dev/sda8 is the swap partition): /etc/fstab file: # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sda6 during installation UUID=4c11e82c-5fe9-49d5-92d9-cdaa6865c991 / ext4 errors=remount-ro 0 1 # /boot was on /dev/sda5 during installation UUID=4031413e-e89f-49a9-b54c-e887286bb15e /boot ext4 defaults 0 2 # /home was on /dev/sda7 during installation UUID=d5bbfc6f-482a-464e-9f26-fd213230ae84 /home ext4 defaults 0 2 # swap was on /dev/sda8 during installation UUID=5da2c720-8787-4332-9317-7d96cf1e9b80 none swap sw 0 0 /dev/mapper/cryptswap1 none swap sw 0 0 output of sudo mount: /dev/sda6 on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=0755) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880) none on /run/shm type tmpfs (rw,nosuid,nodev) /dev/sda5 on /boot type ext4 (rw) /dev/sda7 on /home type ext4 (rw) /home/undisclosed/.Private on /home/undisclosed type ecryptfs (ecryptfs_check_dev_ruid,ecryptfs_cipher=aes,ecryptfs_key_bytes=16,ecryptfs_unlink_sigs,ecryptfs_sig=cbae1771abd34009,ecryptfs_fnek_sig=7cefe2f59aab8e58) gvfs-fuse-daemon on /home/undisclosed/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=undisclosed) output of sudo blkid (note that /dev/sda8 is missing): /dev/sda1: LABEL="SYSTEM" UUID="960490E80490CC9D" TYPE="ntfs" /dev/sda2: UUID="D4043140043126C0" TYPE="ntfs" /dev/sda3: LABEL="Shared" UUID="80F613E1F613D5EE" TYPE="ntfs" /dev/sda5: UUID="4031413e-e89f-49a9-b54c-e887286bb15e" TYPE="ext4" /dev/sda6: UUID="4c11e82c-5fe9-49d5-92d9-cdaa6865c991" TYPE="ext4" /dev/sda7: UUID="d5bbfc6f-482a-464e-9f26-fd213230ae84" TYPE="ext4" /dev/mapper/cryptswap1: UUID="41fa147a-3e2c-4e61-b29b-3f240fffbba0" TYPE="swap" output of sudo fdisk -l: Disk /dev/mapper/cryptswap1 doesn't contain a valid partition table Disk /dev/sda: 320.1 GB, 320072933376 bytes 255 heads, 63 sectors/track, 38913 cylinders, total 625142448 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xdec3fed2 Device Boot Start End Blocks Id System /dev/sda1 * 2048 409599 203776 7 HPFS/NTFS/exFAT /dev/sda2 409600 210135039 104862720 7 HPFS/NTFS/exFAT /dev/sda3 210135040 415422463 102643712 7 HPFS/NTFS/exFAT /dev/sda4 415424510 625141759 104858625 5 Extended /dev/sda5 415424512 415922175 248832 83 Linux /dev/sda6 415924224 515921919 49998848 83 Linux /dev/sda7 515923968 621389823 52732928 83 Linux /dev/sda8 621391872 625141759 1874944 82 Linux swap / Solaris Disk /dev/mapper/cryptswap1: 1919 MB, 1919942656 bytes 255 heads, 63 sectors/track, 233 cylinders, total 3749888 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0xaf5321b5 /etc/initramfs-tools/conf.d/resume file: RESUME=UUID=5da2c720-8787-4332-9317-7d96cf1e9b80 /etc/crypttab file: cryptswap1 /dev/sda8 /dev/urandom swap,cipher=aes-cbc-essiv:sha256 output of sudo swapon -as: Filename Type Size Used Priority /dev/mapper/cryptswap1 partition 1874940 0 -1 output of sudo free -m: total used free shared buffers cached Mem: 1476 1296 179 0 35 671 -/+ buffers/cache: 590 886 Swap: 1830 0 1830 So, how can this be fixed?

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• Educause Top-Ten IT Issues - the most change in a decade or more

  - by user739873

  The Education IT Issue Panel has released the 2012 top-ten issues facing higher education IT leadership, and instead of the customary reshuffling of the same deck, the issues reflect much of the tumult and dynamism facing higher education generally.  I find it interesting (and encouraging) that at the top of this year's list is "Updating IT Professionals' Skills and Roles to Accommodate Emerging Technologies and Changing IT Management and Service Delivery Models."  This reflects, in my view, the realization that higher education IT must change in order to fully realize the potential for transforming the institution, and therefore it's people must learn new skills, understand and accept new ways of solving problems, and not be tied down by past practices or institutional inertia. What follows in the remaining 9 top issues all speak, in some form or fashion, to the need for dramatic change, but not just in the areas of "funding IT" (code for cost containment or reduction), but rather the need to increase effectiveness and efficiency of the institution through the use of technology—leveraging the wave of BYOD (Bring Your Own Device) to the institution's advantage, rather than viewing it as a threat and a problem to be contained. Although it's #10 of 10, IT Governance (and establishment and implementation of the governance model throughout the institution) is key to effectively acting upon many of the preceding issues in this year's list.  In the majority of cases, technology exists to meet the needs and requirements to effectively address many of the challenges outlined in top-ten issues list. Which brings me to my next point. Although I try not to sound too much like an Oracle commercial in these (all too infrequent) blog posts, I can't help but point out how much confluence there is between several of the top issues this year and what my colleagues and I have been evangelizing for some time. Starting from the bottom of the list up: 1) I'm gratified that research and the IT challenges it presents has made the cut.  Big Data (or Large Data as it's phased in the report) is rapidly going to overwhelm much of what exists today even at our most prepared and well-equipped research universities.  Combine large data with the significantly more stringent requirements around data preservation, archiving, sharing, curation, etc. coming from granting agencies like NSF, and you have the brewing storm that could result in a lot of "one-off" solutions to a problem that could very well be addressed collectively and "at scale."   2) Transformative effects of IT – while I see more and more examples of this, there is still much more that can be achieved. My experience tells me that culture (as the report indicates or at least poses the question) gets in the way more than technology not being up to task.  We spend too much time on "context" and not "core," and get lost in the weeds on the journey to truly transforming the institution with technology. 3) Analytics as a key element in improving various institutional outcomes.  In our work around Student Success, we see predictive "academic" analytics as essential to getting in front of the Student Success issue, regardless of how an institution or collections of institutions defines success.  Analytics must be part of the fabric of the key academic enterprise applications, not a bolt-on.  We will spend a significant amount of time on this topic during our semi-annual Education Industry Strategy Council meeting in Washington, D.C. later this month. 4) Cloud strategy for the broad range of applications in the academic enterprise.  Some of the recent work by Casey Green at the Campus Computing Survey would seem to indicate that there is movement in this area but mostly in what has been termed "below the campus" application areas such as collaboration tools, recruiting, and alumni relations.  It's time to get serious about sourcing elements of mature applications like student information systems, HR, Finance, etc. leveraging a model other than traditional on-campus custom. I've only selected a few areas of the list to highlight, but the unifying theme here (and this is where I run the risk of sounding like an Oracle commercial) is that these lofty goals cry out for partners that can bring economies of scale to bear on the problems married with a deep understanding of the nuances unique to higher education.  In a recent piece in Educause Review on Student Information Systems, the author points out that "best of breed is back". Unfortunately I am compelled to point out that best of breed is a large part of the reason we have made as little progress as we have as an industry in advancing some of the causes outlined above.  Don't confuse "integrated" and "full stack" for vendor lock-in.  The best-of-breed market forces that Ron points to ensure that solutions have to be "integratable" or they don't survive in the marketplace. However, by leveraging the efficiencies afforded by adopting solutions that are pre-integrated (and possibly metered out as a service) allows us to shed unnecessary costs – as difficult as these decisions are to make and to drive throughout the organization. Cole

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• What Can We Learn About Software Security by Going to the Gym

  - by Nick Harrison

  There was a recent rash of car break-ins at the gym. Not an epidemic by any stretch, probably 4 or 5, but still... My gym used to allow you to hang your keys from a peg board at the front desk. This way you could come to the gym dressed to work out, lock your valuables in your car, and not have anything to worry about. Ignorance is bliss. The problem was that anyone who wanted to could go pick up your car keys, click the unlock button and find your car. Once there, they could rummage through your stuff and then walk back in and finish their workout as if nothing had happened. The people doing this were a little smatter then the average thief and would swipe some but not all of your cash leaving everything else in place. Most thieves would steal the whole car and be busted more quickly. The victims were unaware that anything had happened for several days. Fortunately, once the victims realized what had happened, the gym was still able to pull security tapes and find out who was misbehaving. All of the bad guys were busted, and everyone can now breathe a sigh of relieve. It is once again safe to go to the gym. Except there was still a fundamental problem. Putting your keys on a peg board by the front door is just asking for bad things to happen. One person got busted exploiting this security flaw. Others can still be exploiting it. In fact, others may well have been exploiting it and simply never got caught. How long would it take you to realize that $10 was missing from your wallet, if everything else was there? How would you even know when it went missing? Would you go to the front desk and even bother to ask them to review security tapes if you were only missing a small amount. Once highlighted, it is easy to see how commonly such vulnerability may have been exploited. So the gym did the very reasonable precaution of removing the peg board. To me the most shocking part of this story is the resulting uproar from gym members losing the convenient key peg. How dare they remove the trusted peg board? How can I work out now, I have to carry my keys from machine to machine? How can I enjoy my workout with this added inconvenience? This all happened a couple of weeks ago, and some people are still complaining. In light of the recent high profile hacking, there are a couple of parallels that can be drawn. Many web sites are riddled with vulnerabilities are crazy and easily exploitable as leaving your car keys by the front door while you work out. No one ever considered thanking the people who were swiping these keys for pointing out the vulnerability. Without a hesitation, they had their gym memberships revoked and are awaiting prosecution. The gym did recognize the vulnerability for what it is, and closed up that attack vector. What can we learn from this? Monitoring and logging will not prevent a crime but they will allow us to identify that a crime took place and may help track down who did it. Once we find a security weakness, we need to eliminate it. We may never identify and eliminate all security weaknesses, but we cannot allow well known vulnerabilities to persist in our system. In our case, we are not likely to meet resistance from end users. We are more likely to meet resistance from stake holders, product owners, keeper of schedules and budgets. We may meet resistance from integration partners, co workers, and third party vendors. Regardless of the source, we will see resistance, but the weakness needs to be dealt with. There is no need to glorify a cracker for bringing to light a security weakness. Regardless of their claimed motives, they are not heroes. There is also no point in wasting time defending weaknesses once they are identified. Deal with the weakness and move on. In may be embarrassing to find security weaknesses in our systems, but it is even more embarrassing to continue ignoring them. Even if it is unpopular, we need to seek out security weaknesses and eliminate them when we find them. http://www.sans.org has put together the Common Weakness Enumeration http://cwe.mitre.org/ which lists out common weaknesses. The site navigation takes a little getting used to, but there is a treasure trove here. Here is the detail page for SQL Injection. It clearly states how this can be exploited, in case anyone doubts that the weakness should be taken seriously, and more importantly how to mitigate the risk.

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• YouTube Scalability Lessons

  - by Bertrand Matthelié

  @font-face { font-family: "Arial"; }@font-face { font-family: "Courier New"; }@font-face { font-family: "Wingdings"; }@font-face { font-family: "Calibri"; }@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }h2 { margin: 12pt 0cm 3pt; page-break-after: avoid; font-size: 14pt; font-family: "Times New Roman"; font-style: italic; }a:link, span.MsoHyperlink { color: blue; text-decoration: underline; }a:visited, span.MsoHyperlinkFollowed { color: purple; text-decoration: underline; }span.Heading2Char { font-family: Calibri; font-weight: bold; font-style: italic; }div.Section1 { page: Section1; }ol { margin-bottom: 0cm; }ul { margin-bottom: 0cm; } Very interesting blog post by Todd Hoff at highscalability.com presenting “7 Years of YouTube Scalability Lessons in 30 min” based on a presentation from Mike Solomon, one of the original engineers at YouTube: …. The key takeaway away of the talk for me was doing a lot with really simple tools. While many teams are moving on to more complex ecosystems, YouTube really does keep it simple. They program primarily in Python, use MySQL as their database, they’ve stuck with Apache, and even new features for such a massive site start as a very simple Python program. That doesn’t mean YouTube doesn’t do cool stuff, they do, but what makes everything work together is more a philosophy or a way of doing things than technological hocus pocus. What made YouTube into one of the world’s largest websites? Read on and see... Stats @font-face { font-family: "Arial"; }@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; } 4 billion Views a day 60 hours of video is uploaded every minute 350+ million devices are YouTube enabled Revenue double in 2010 The number of videos has gone up 9 orders of magnitude and the number of developers has only gone up two orders of magnitude. 1 million lines of Python code Stack @font-face { font-family: "Arial"; }@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: "Times New Roman"; }div.Section1 { page: Section1; } Python - most of the lines of code for YouTube are still in Python. Everytime you watch a YouTube video you are executing a bunch of Python code. Apache - when you think you need to get rid of it, you don’t. Apache is a real rockstar technology at YouTube because they keep it simple. Every request goes through Apache. Linux - the benefit of Linux is there’s always a way to get in and see how your system is behaving. No matter how bad your app is behaving, you can take a look at it with Linux tools like strace and tcpdump. MySQL - is used a lot. When you watch a video you are getting data from MySQL. Sometime it’s used a relational database or a blob store. It’s about tuning and making choices about how you organize your data. Vitess- a  new project released by YouTube, written in Go, it’s a frontend to MySQL. It does a lot of optimization on the fly, it rewrites queries and acts as a proxy. Currently it serves every YouTube database request. It’s RPC based. Zookeeper - a distributed lock server. It’s used for configuration. Really interesting piece of technology. Hard to use correctly so read the manual Wiseguy - a CGI servlet container. Spitfire - a templating system. It has an abstract syntax tree that let’s them do transformations to make things go faster. Serialization formats - no matter which one you use, they are all expensive. Measure. Don’t use pickle. Not a good choice. Found protocol buffers slow. They wrote their own BSON implementation, which is 10-15 time faster than the one you can download. ...Contiues. Read the blog Watch the video

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• How do I mount my External HDD with filesystem type errors?

  - by Snuggie

  I am a relatively new Ubuntu user and I am having some difficulty mounting my external 2TB HDD. When I first installed Linux my external HDD was working just fine, however, it has stopped working and I have a lot of important files on there that I need. Before my HDD would automatically mount and no worries. Now, however, it doesn't automatically mount and when I try to manually mount it I keep running into filesystem type errors that I can't seem to get past. Below are images that depict my step by step process of how I am trying to mount my HDD along with the errors I am receiving. If anybody has any idea what I am doing wrong or how to correct the issue I would greatly appreciate it. Step 1) Ensure the computer recognizes my external HDD. pj@PJ:~$ dmesg ... [ 5790.367910] scsi 7:0:0:0: Direct-Access WD My Passport 0748 1022 PQ: 0 ANSI: 6 [ 5790.368278] scsi 7:0:0:1: Enclosure WD SES Device 1022 PQ: 0 ANSI: 6 [ 5790.370122] sd 7:0:0:0: Attached scsi generic sg2 type 0 [ 5790.370310] ses 7:0:0:1: Attached Enclosure device [ 5790.370462] ses 7:0:0:1: Attached scsi generic sg3 type 13 [ 5792.971601] sd 7:0:0:0: [sdb] 3906963456 512-byte logical blocks: (2.00 TB/1.81 TiB) [ 5792.972148] sd 7:0:0:0: [sdb] Write Protect is off [ 5792.972162] sd 7:0:0:0: [sdb] Mode Sense: 47 00 10 08 [ 5792.972591] sd 7:0:0:0: [sdb] No Caching mode page found [ 5792.972605] sd 7:0:0:0: [sdb] Assuming drive cache: write through [ 5792.975235] sd 7:0:0:0: [sdb] No Caching mode page found [ 5792.975249] sd 7:0:0:0: [sdb] Assuming drive cache: write through [ 5792.987504] sdb: sdb1 [ 5792.988900] sd 7:0:0:0: [sdb] No Caching mode page found [ 5792.988911] sd 7:0:0:0: [sdb] Assuming drive cache: write through [ 5792.988920] sd 7:0:0:0: [sdb] Attached SCSI disk Step 2) Check if it mounted properly (it does not) pj@PJ:~$ df -ah Filesystem Size Used Avail Use% Mounted on /dev/sda1 682G 3.9G 644G 1% / proc 0 0 0 - /proc sysfs 0 0 0 - /sys none 0 0 0 - /sys/fs/fuse/connections none 0 0 0 - /sys/kernel/debug none 0 0 0 - /sys/kernel/security udev 2.9G 4.0K 2.9G 1% /dev devpts 0 0 0 - /dev/pts tmpfs 1.2G 928K 1.2G 1% /run none 5.0M 0 5.0M 0% /run/lock none 2.9G 156K 2.9G 1% /run/shm gvfs-fuse-daemon 0 0 0 - /home/pj/.gvfs Step 3) Try mounting manually using NTFS and VFAT (both as SDB and SDB1) pj@PJ:~$ sudo mount /dev/sdb /media/Passport/ NTFS signature is missing. Failed to mount '/dev/sdb': Invalid argument The device '/dev/sdb' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around? pj@PJ:~$ sudo mount /dev/sdb1 /media/Passport/ NTFS signature is missing. Failed to mount '/dev/sdb1': Invalid argument The device '/dev/sdb1' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around? pj@PJ:~$ sudo mount -t ntfs /dev/sdb /media/Passport/ NTFS signature is missing. Failed to mount '/dev/sdb': Invalid argument The device '/dev/sdb' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around? pj@PJ:~$ sudo mount -t vfat /dev/sdb /media/Passport/ mount: wrong fs type, bad option, bad superblock on /dev/sdb, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so pj@PJ:~$ sudo mount -t ntfs /dev/sdb1 /media/Passport/ NTFS signature is missing. Failed to mount '/dev/sdb1': Invalid argument The device '/dev/sdb1' doesn't seem to have a valid NTFS. Maybe the wrong device is used? Or the whole disk instead of a partition (e.g. /dev/sda, not /dev/sda1)? Or the other way around? pj@PJ:~$ sudo mount -t vfat /dev/sdb1 /media/Passport/ mount: wrong fs type, bad option, bad superblock on /dev/sdb1, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so

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• Atheros 922 PCI WIFI is disabled in Unity but enabled in terminal - How to get it to work?

  - by zewone

  I am trying to get my PCI Wireless Atheros 922 card to work. It is disabled in Unity: both the network utility and the desktop (see screenshot http://www.amisdurailhalanzy.be/Screenshot%20from%202012-10-25%2013:19:54.png) I tried many different advises on many different forums. Installed 12.10 instead of 12.04, enabled all interfaces... etc. I have read about the aht9 driver... The terminal shows no hw or sw lock for the Atheros card, nevertheless, it is still disabled. Nothing worked so far, the card is still disabled. Any help is much appreciated. Here are more tech details: myuser@adri1:~$ sudo lshw -C network *-network:0 DISABLED description: Wireless interface product: AR922X Wireless Network Adapter vendor: Atheros Communications Inc. physical id: 2 bus info: pci@0000:03:02.0 logical name: wlan1 version: 01 serial: 00:18:e7:cd:68:b1 width: 32 bits clock: 66MHz capabilities: pm bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=ath9k driverversion=3.5.0-17-generic firmware=N/A latency=168 link=no multicast=yes wireless=IEEE 802.11bgn resources: irq:18 memory:d8000000-d800ffff *-network:1 description: Ethernet interface product: VT6105/VT6106S [Rhine-III] vendor: VIA Technologies, Inc. physical id: 6 bus info: pci@0000:03:06.0 logical name: eth0 version: 8b serial: 00:11:09:a3:76:4a size: 10Mbit/s capacity: 100Mbit/s width: 32 bits clock: 33MHz capabilities: pm bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=via-rhine driverversion=1.5.0 duplex=half latency=32 link=no maxlatency=8 mingnt=3 multicast=yes port=MII speed=10Mbit/s resources: irq:18 ioport:d300(size=256) memory:d8013000-d80130ff *-network DISABLED description: Wireless interface physical id: 1 bus info: usb@1:8.1 logical name: wlan0 serial: 00:11:09:51:75:36 capabilities: ethernet physical wireless configuration: broadcast=yes driver=rt2500usb driverversion=3.5.0-17-generic firmware=N/A link=no multicast=yes wireless=IEEE 802.11bg myuser@adri1:~$ sudo rfkill list all 0: hci0: Bluetooth Soft blocked: no Hard blocked: no 1: phy1: Wireless LAN Soft blocked: no Hard blocked: yes 2: phy0: Wireless LAN Soft blocked: no Hard blocked: no myuser@adri1:~$ dmesg | grep wlan0 [ 15.114235] IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready myuser@adri1:~$ dmesg | egrep 'ath|firm' [ 14.617562] ath: EEPROM regdomain: 0x30 [ 14.617568] ath: EEPROM indicates we should expect a direct regpair map [ 14.617572] ath: Country alpha2 being used: AM [ 14.617575] ath: Regpair used: 0x30 [ 14.637778] ieee80211 phy0: >Selected rate control algorithm 'ath9k_rate_control' [ 14.639410] Registered led device: ath9k-phy0 myuser@adri1:~$ dmesg | grep wlan1 [ 15.119922] IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready myuser@adri1:~$ lspci -nn | grep 'Atheros' 03:02.0 Network controller [0280]: Atheros Communications Inc. AR922X Wireless Network Adapter [168c:0029] (rev 01) myuser@adri1:~$ sudo ifconfig eth0 Link encap:Ethernet HWaddr 00:11:09:a3:76:4a inet addr:192.168.2.2 Bcast:192.168.2.255 Mask:255.255.255.0 inet6 addr: fe80::211:9ff:fea3:764a/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:5457 errors:0 dropped:0 overruns:0 frame:0 TX packets:2548 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:3425684 (3.4 MB) TX bytes:282192 (282.1 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:16436 Metric:1 RX packets:590 errors:0 dropped:0 overruns:0 frame:0 TX packets:590 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:53729 (53.7 KB) TX bytes:53729 (53.7 KB) myuser@adri1:~$ sudo iwconfig wlan0 IEEE 802.11bg ESSID:off/any Mode:Managed Access Point: Not-Associated Tx-Power=off Retry long limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:on lo no wireless extensions. eth0 no wireless extensions. wlan1 IEEE 802.11bgn ESSID:off/any Mode:Managed Access Point: Not-Associated Tx-Power=0 dBm Retry long limit:7 RTS thr:off Fragment thr:off Encryption key:off Power Management:off myuser@adri1:~$ lsmod | grep "ath9k" ath9k 116549 0 mac80211 461161 3 rt2x00usb,rt2x00lib,ath9k ath9k_common 13783 1 ath9k ath9k_hw 376155 2 ath9k,ath9k_common ath 19187 3 ath9k,ath9k_common,ath9k_hw cfg80211 175375 4 rt2x00lib,ath9k,mac80211,ath myuser@adri1:~$ iwlist scan wlan0 Failed to read scan data : Network is down lo Interface doesn't support scanning. eth0 Interface doesn't support scanning. wlan1 Failed to read scan data : Network is down myuser@adri1:~$ lsb_release -d Description: Ubuntu 12.10 myuser@adri1:~$ uname -mr 3.5.0-17-generic i686  Any help much appreciated... Thanks, Philippe 31-10-2012 ... I have some more updates. When I do the following command it does see my Wifi router... So even if it is still disabled... the card seems to work and see the router (ESSID:"5791BC26-CE9C-11D1-97BF-0000F81E") See below: sudo iwlist wlan1 scanning wlan1 Scan completed : Cell 01 - Address: 00:19:70:8F:B0:EA Channel:10 Frequency:2.457 GHz (Channel 10) Quality=51/70 Signal level=-59 dBm Encryption key:on ESSID:"5791BC26-CE9C-11D1-97BF-0000F81E" Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 6 Mb/s 9 Mb/s; 12 Mb/s; 18 Mb/s Bit Rates:24 Mb/s; 36 Mb/s; 48 Mb/s; 54 Mb/s Mode:Master Extra:tsf=000000025dbf2188 Extra: Last beacon: 108ms ago IE: Unknown: 002035373931424332362D434539432D313144312D393742462D3030303046383145 IE: Unknown: 010882848B960C121824 IE: Unknown: 03010A IE: Unknown: 0706424520010D14 IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: Unknown: 2A0100 IE: Unknown: 32043048606C IE: Unknown: DD180050F2020101030003A4000027A4000042435E0062322F00 IE: Unknown: DD0900037F01010000FF7F IE: Unknown: DD0A00037F04010000000000

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• Thread.Interrupt Is Evil

  - by Alois Kraus

  Recently I have found an interesting issue with Thread.Interrupt during application shutdown. Some application was crashing once a week and we had not really a clue what was the issue. Since it happened not very often it was left as is until we have got some memory dumps during the crash. A memory dump usually means WindDbg which I really like to use (I know I am one of the very few fans of it).  After a quick analysis I did find that the main thread already had exited and the thread with the crash was stuck in a Monitor.Wait. Strange Indeed. Running the application a few thousand times under the debugger would potentially not have shown me what the reason was so I decided to what I call constructive debugging. I did create a simple Console application project and try to simulate the exact circumstances when the crash did happen from the information I have via memory dump and source code reading. The thread that was  crashing was actually MS code from an old version of the Microsoft Caching Application Block. From reading the code I could conclude that the main thread did call the Dispose method on the CacheManger class which did call Thread.Interrupt on the cache scavenger thread which was just waiting for work to do. My first version of the repro looked like this   static void Main(string[] args) { Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); } static void ThreadFunc() { while (true) { object value = Dequeue(); // block until unblocked or awaken via ThreadInterruptedException } } static object WaitObject = new object(); static object Dequeue() { object lret = "got value"; try { lock (WaitObject) { } } catch (ThreadInterruptedException) { Console.WriteLine("Got ThreadInterruptException"); lret = null; } return lret; } I do start a background thread and call Thread.Interrupt on it and then directly let the application terminate. The thread in the meantime does plenty of Monitor.Enter/Leave calls to simulate work on it. This first version did not crash. So I need to dig deeper. From the memory dump I did know that the finalizer thread was doing just some critical finalizers which were closing file handles. Ok lets add some long running finalizers to the sample. class FinalizableObject : CriticalFinalizerObject { ~FinalizableObject() { Console.WriteLine("Hi we are waiting to finalize now and block the finalizer thread for 5s."); Thread.Sleep(5000); } } class Program { static void Main(string[] args) { FinalizableObject fin = new FinalizableObject(); Thread t = new Thread(ThreadFunc) { IsBackground = true, Name = "Test Thread" }; t.Start(); Console.WriteLine("Interrupt Thread"); t.Interrupt(); GC.KeepAlive(fin); // prevent finalizing it too early // After leaving main the other thread is woken up via Thread.Abort // while we are finalizing. This causes a stackoverflow in the CLR ThreadAbortException handling at this time. } With this changed Main method and a blocking critical finalizer I did get my crash just like the real application. The funny thing is that this is actually a CLR bug. When the main method is left the CLR does suspend all threads except the finalizer thread and declares all objects as garbage. After the normal finalizers were called the critical finalizers are executed to e.g. free OS handles (usually). Remember that I did call Thread.Interrupt as one of the last methods in the Main method. The Interrupt method is actually asynchronous and does wake a thread up and throws a ThreadInterruptedException only once unlike Thread.Abort which does rethrow the exception when an exception handling clause is left. It seems that the CLR does not expect that a frozen thread does wake up again while the critical finalizers are executed. While trying to raise a ThreadInterrupedException the CLR goes down with an stack overflow. Ups not so nice. Why has this nobody noticed for years is my next question. As it turned out this error does only happen on the CLR for .NET 4.0 (x86 and x64). It does not show up in earlier or later versions of the CLR. I have reported this issue on connect here but so far it was not confirmed as a CLR bug. But I would be surprised if my console application was to blame for a stack overflow in my test thread in a Monitor.Wait call. What is the moral of this story? Thread.Abort is evil but Thread.Interrupt is too. It is so evil that even the CLR of .NET 4.0 contains a race condition during the CLR shutdown. When the CLR gurus can get it wrong the chances are high that you get it wrong too when you use this constructs. If you do not believe me see what Patrick Smacchia does blog about Thread.Abort and List.Sort. Not only the CLR creators can get it wrong. The BCL writers do sometimes have a hard time with correct exception handling as well. If you do tell me that you use Thread.Abort frequently and never had problems with it I do suspect that you do not have looked deep enough into your application to find such sporadic errors.

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• A Basic Thread

  - by Joe Mayo

  Most of the programs written are single-threaded, meaning that they run on the main execution thread. For various reasons such as performance, scalability, and/or responsiveness additional threads can be useful. .NET has extensive threading support, from the basic threads introduced in v1.0 to the Task Parallel Library (TPL) introduced in v4.0. To get started with threads, it's helpful to begin with the basics; starting a Thread. Why Do I Care? The scenario I'll use for needing to use a thread is writing to a file.  Sometimes, writing to a file takes a while and you don't want your user interface to lock up until the file write is done. In other words, you want the application to be responsive to the user. How Would I Go About It? The solution is to launch a new thread that performs the file write, allowing the main thread to return to the user right away.  Whenever the file writing thread completes, it will let the user know.  In the meantime, the user is free to interact with the program for other tasks. The following examples demonstrate how to do this. Show Me the Code? The code we'll use to work with threads is in the System.Threading namespace, so you'll need the following using directive at the top of the file: using System.Threading; When you run code on a thread, the code is specified via a method.  Here's the code that will execute on the thread: private static void WriteFile() { Thread.Sleep(1000); Console.WriteLine("File Written."); } The call to Thread.Sleep(1000) delays thread execution. The parameter is specified in milliseconds, and 1000 means that this will cause the program to sleep for approximately 1 second.  This method happens to be static, but that's just part of this example, which you'll see is launched from the static Main method.  A thread could be instance or static.  Notice that the method does not have parameters and does not have a return type. As you know, the way to refer to a method is via a delegate.  There is a delegate named ThreadStart in System.Threading that refers to a method without parameters or return type, shown below: ThreadStart fileWriterHandlerDelegate = new ThreadStart(WriteFile); I'll show you the whole program below, but the ThreadStart instance above goes in the Main method. The thread uses the ThreadStart instance, fileWriterHandlerDelegate, to specify the method to execute on the thread: Thread fileWriter = new Thread(fileWriterHandlerDelegate); As shown above, the argument type for the Thread constructor is the ThreadStart delegate type. The fileWriterHandlerDelegate argument is an instance of the ThreadStart delegate type. This creates an instance of a thread and what code will execute, but the new thread instance, fileWriter, isn't running yet. You have to explicitly start it, like this: fileWriter.Start(); Now, the code in the WriteFile method is executing on a separate thread. Meanwhile, the main thread that started the fileWriter thread continues on it's own.  You have two threads running at the same time. Okay, I'm Starting to Get Glassy Eyed. How Does it All Fit Together? The example below is the whole program, pulling all the previous bits together. It's followed by its output and an explanation. using System; using System.Threading; namespace BasicThread { class Program { static void Main() { ThreadStart fileWriterHandlerDelegate = new ThreadStart(WriteFile); Thread fileWriter = new Thread(fileWriterHandlerDelegate); Console.WriteLine("Starting FileWriter"); fileWriter.Start(); Console.WriteLine("Called FileWriter"); Console.ReadKey(); } private static void WriteFile() { Thread.Sleep(1000); Console.WriteLine("File Written"); } } } And here's the output: Starting FileWriter Called FileWriter File Written So, Why are the Printouts Backwards? The output above corresponds to Console.Writeline statements in the program, with the second and third seemingly reversed. In a single-threaded program, "File Written" would print before "Called FileWriter". However, this is a multi-threaded (2 or more threads) program.  In multi-threading, you can't make any assumptions about when a given thread will run.  In this case, I added the Sleep statement to the WriteFile method to greatly increase the chances that the message from the main thread will print first. Without the Thread.Sleep, you could run this on a system with multiple cores and/or multiple processors and potentially get different results each time. Interesting Tangent but What Should I Get Out of All This? Going back to the main point, launching the WriteFile method on a separate thread made the program more responsive.  The file writing logic ran for a while, but the main thread returned to the user, as demonstrated by the print out of "Called FileWriter".  When the file write finished, it let the user know via another print statement. This was a very efficient use of CPU resources that made for a more pleasant user experience. Joe

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• SQL Server - Rebuilding Indexes

  - by Renso

  Goal: Rebuild indexes in SQL server. This can be done one at a time or with the example script below to rebuild all index for a specified table or for all tables in a given database. Why? The data in indexes gets fragmented over time. That means that as the index grows, the newly added rows to the index are physically stored in other sections of the allocated database storage space. Kind of like when you load your Christmas shopping into the trunk of your car and it is full you continue to load some on the back seat, in the same way some storage buffer is created for your index but once that runs out the data is then stored in other storage space and your data in your index is no longer stored in contiguous physical pages. To access the index the database manager has to "string together" disparate fragments to create the full-index and create one contiguous set of pages for that index. Defragmentation fixes that. What does the fragmentation affect?Depending of course on how large the table is and how fragmented the data is, can cause SQL Server to perform unnecessary data reads, slowing down SQL Server’s performance.Which index to rebuild?As a rule consider that when reorganize a table's clustered index, all other non-clustered indexes on that same table will automatically be rebuilt. A table can only have one clustered index.How to rebuild all the index for one table:The DBCC DBREINDEX command will not automatically rebuild all of the indexes on a given table in a databaseHow to rebuild all indexes for all tables in a given database:USE [myDB]    -- enter your database name hereDECLARE @tableName varchar(255)DECLARE TableCursor CURSOR FORSELECT table_name FROM information_schema.tablesWHERE table_type = 'base table'OPEN TableCursorFETCH NEXT FROM TableCursor INTO @tableNameWHILE @@FETCH_STATUS = 0BEGINDBCC DBREINDEX(@tableName,' ',90)     --a fill factor of 90%FETCH NEXT FROM TableCursor INTO @tableNameENDCLOSE TableCursorDEALLOCATE TableCursorWhat does this script do?Reindexes all indexes in all tables of the given database. Each index is filled with a fill factor of 90%. While the command DBCC DBREINDEX runs and rebuilds the indexes, that the table becomes unavailable for use by your users temporarily until the rebuild has completed, so don't do this during production  hours as it will create a shared lock on the tables, although it will allow for read-only uncommitted data reads; i.e.e SELECT.What is the fill factor?Is the percentage of space on each index page for storing data when the index is created or rebuilt. It replaces the fill factor when the index was created, becoming the new default for the index and for any other nonclustered indexes rebuilt because a clustered index is rebuilt. When fillfactor is 0, DBCC DBREINDEX uses the fill factor value last specified for the index. This value is stored in the sys.indexes catalog view. If fillfactor is specified, table_name and index_name must be specified. If fillfactor is not specified, the default fill factor, 100, is used.How do I determine the level of fragmentation?Run the DBCC SHOWCONTIG command. However this requires you to specify the ID of both the table and index being. To make it a lot easier by only requiring you to specify the table name and/or index you can run this script:DECLARE@ID int,@IndexID int,@IndexName varchar(128)--Specify the table and index namesSELECT @IndexName = ‘index_name’    --name of the indexSET @ID = OBJECT_ID(‘table_name’)  -- name of the tableSELECT @IndexID = IndIDFROM sysindexesWHERE id = @ID AND name = @IndexName--Show the level of fragmentationDBCC SHOWCONTIG (@id, @IndexID)Here is an example:DBCC SHOWCONTIG scanning 'Tickets' table...Table: 'Tickets' (1829581556); index ID: 1, database ID: 13TABLE level scan performed.- Pages Scanned................................: 915- Extents Scanned..............................: 119- Extent Switches..............................: 281- Avg. Pages per Extent........................: 7.7- Scan Density [Best Count:Actual Count].......: 40.78% [115:282]- Logical Scan Fragmentation ..................: 16.28%- Extent Scan Fragmentation ...................: 99.16%- Avg. Bytes Free per Page.....................: 2457.0- Avg. Page Density (full).....................: 69.64%DBCC execution completed. If DBCC printed error messages, contact your system administrator.What's important here?The Scan Density; Ideally it should be 100%. As time goes by it drops as fragmentation occurs. When the level drops below 75%, you should consider re-indexing.Here are the results of the same table and clustered index after running the script:DBCC SHOWCONTIG scanning 'Tickets' table...Table: 'Tickets' (1829581556); index ID: 1, database ID: 13TABLE level scan performed.- Pages Scanned................................: 692- Extents Scanned..............................: 87- Extent Switches..............................: 86- Avg. Pages per Extent........................: 8.0- Scan Density [Best Count:Actual Count].......: 100.00% [87:87]- Logical Scan Fragmentation ..................: 0.00%- Extent Scan Fragmentation ...................: 22.99%- Avg. Bytes Free per Page.....................: 639.8- Avg. Page Density (full).....................: 92.10%DBCC execution completed. If DBCC printed error messages, contact your system administrator.What's different?The Scan Density has increased from 40.78% to 100%; no fragmentation on the clustered index. Note that since we rebuilt the clustered index, all other index were also rebuilt.

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• ADF Business Components

  - by Arda Eralp

  ADF Business Components and JDeveloper simplify the development, delivery, and customization of business applications for the Java EE platform. With ADF Business Components, developers aren't required to write the application infrastructure code required by the typical Java EE application to: Connect to the database Retrieve data Lock database records Manage transactions   ADF Business Components addresses these tasks through its library of reusable software components and through the supporting design time facilities in JDeveloper. Most importantly, developers save time using ADF Business Components since the JDeveloper design time makes typical development tasks entirely declarative. In particular, JDeveloper supports declarative development with ADF Business Components to: Author and test business logic in components which automatically integrate with databases Reuse business logic through multiple SQL-based views of data, supporting different application tasks Access and update the views from browser, desktop, mobile, and web service clients Customize application functionality in layers without requiring modification of the delivered application The goal of ADF Business Components is to make the business services developer more productive.   ADF Business Components provides a foundation of Java classes that allow your business-tier application components to leverage the functionality provided in the following areas: Simplifying Data Access Design a data model for client displays, including only necessary data Include master-detail hierarchies of any complexity as part of the data model Implement end-user Query-by-Example data filtering without code Automatically coordinate data model changes with business services layer Automatically validate and save any changes to the database   Enforcing Business Domain Validation and Business Logic Declaratively enforce required fields, primary key uniqueness, data precision-scale, and foreign key references Easily capture and enforce both simple and complex business rules, programmatically or declaratively, with multilevel validation support Navigate relationships between business domain objects and enforce constraints related to compound components   Supporting Sophisticated UIs with Multipage Units of Work Automatically reflect changes made by business service application logic in the user interface Retrieve reference information from related tables, and automatically maintain the information when the user changes foreign-key values Simplify multistep web-based business transactions with automatic web-tier state management Handle images, video, sound, and documents without having to use code Synchronize pending data changes across multiple views of data Consistently apply prompts, tooltips, format masks, and error messages in any application Define custom metadata for any business components to support metadata-driven user interface or application functionality Add dynamic attributes at runtime to simplify per-row state management   Implementing High-Performance Service-Oriented Architecture Support highly functional web service interfaces for business integration without writing code Enforce best-practice interface-based programming style Simplify application security with automatic JAAS integration and audit maintenance "Write once, run anywhere": use the same business service as plain Java class, EJB session bean, or web service   Streamlining Application Customization Extend component functionality after delivery without modifying source code Globally substitute delivered components with extended ones without modifying the application   ADF Business Components implements the business service through the following set of cooperating components: Entity object An entity object represents a row in a database table and simplifies modifying its data by handling all data manipulation language (DML) operations for you. These are basically your 1 to 1 representation of a database table. Each table in the database will have 1 and only 1 EO. The EO contains the mapping between columns and attributes. EO's also contain the business logic and validation. These are you core data services. They are responsible for updating, inserting and deleting records. The Attributes tab displays the actual mapping between attributes and columns, the mapping has following fields: Name : contains the name of the attribute we expose in our data model. Type : defines the data type of the attribute in our application. Column : specifies the column to which we want to map the attribute with Column Type : contains the type of the column in the database   View object A view object represents a SQL query. You use the full power of the familiar SQL language to join, filter, sort, and aggregate data into exactly the shape required by the end-user task. The attributes in the View Objects are actually coming from the Entity Object. In the end the VO will generate a query but you basically build a VO by selecting which EO need to participate in the VO and which attributes of those EO you want to use. That's why you have the Entity Usage column so you can see the relation between VO and EO. In the query tab you can clearly see the query that will be generated for the VO. At this stage we don't need it and just use it for information purpose. In later stages we might use it. Application module An application module is the controller of your data layer. It is responsible for keeping hold of the transaction. It exposes the data model to the view layer. You expose the VO's through the Application Module. This is the abstraction of your data layer which you want to show to the outside word.It defines an updatable data model and top-level procedures and functions (called service methods) related to a logical unit of work related to an end-user task. While the base components handle all the common cases through built-in behavior, customization is always possible and the default behavior provided by the base components can be easily overridden or augmented. When you create EO's, a foreign key will be translated into an association in our model. It defines the type of relation and who is the master and child as well as how the visibility of the association looks like. A similar concept exists to identify relations between view objects. These are called view links. These are almost identical as association except that a view link is based upon attributes defined in the view object. It can also be based upon an association. Here's a short summary: Entity Objects: representations of tables Association: Relations between EO's. Representations of foreign keys View Objects: Logical model View Links: Relationships between view objects Application Model: interface to your application  

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• Exadata?????????INSERT?UPDATE

  - by Liu Maclean(???)

  Hybrid Columnar Compression??????Exadata?????????????,??????????(advanced compression)??,Hybrid columnar compression (HCC) ???Exadata????????HCC???????????CU(compression unit?????),??CU??????????,?????????????????????????,???CU????block??????????????? ???????INSERT/UPDATE??,??????????????,????UPDATE/INSERT???HCC?????????????????? hybrid columnar compression???????????????(bulk initial load)??,??????(direct load)??ALTER TABLE MOVE, IMPDP???????(append INSERT),??HCC??????????????????????? ???????????????????,?????????CU????????? ??????????????HCC?????????????for OLTP?????? ????????: SQL*Plus: Release 11.2.0.2.0 Production on Wed Sep 12 06:14:53 2012 Copyright (c) 1982, 2010, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.2.0.2.0 - Production With the Partitioning, Automatic Storage Management, OLAP, Data Mining and Real Application Testing options SQL> grant dba to scott; Grant succeeded. SQL> conn scott/oracle Connected. SQL> SQL> create table hcc_maclean tablespace users compress for query high as select * from dba_objects; Table created. 1* select rowid,owner,object_name,dbms_rowid.rowid_block_number(rowid) from hcc_maclean where owner='MACLEAN' SQL> / ROWID OWNER OBJECT_NAME DBMS_ROWID.ROWID_BLOCK_NUMBER(ROWID) ------------------------------ ------------------------------ -------------------- ------------------------------------ AAAThuAAEAAAHTJAOI MACLEAN SALES 29897 AAAThuAAEAAAHTJAOJ MACLEAN MYCUSTOMERS 29897 AAAThuAAEAAAHTJAOK MACLEAN MYCUST_ARCHIVE 29897 AAAThuAAEAAAHTJAOL MACLEAN MYCUST_QUERY 29897 AAAThuAAEAAAHTJAOh MACLEAN COMPRESS_QUERY 29897 AAAThuAAEAAAHTJAOi MACLEAN UNCOMPRESS 29897 AAAThuAAEAAAHTJAOj MACLEAN CHAINED_ROWS 29897 AAAThuAAEAAAHTJAOk MACLEAN COMPRESS_QUERY1 29897 8 rows selected. select dbms_rowid.rowid_block_number(rowid),dbms_rowid.rowid_relative_fno(rowid) from hcc_maclean where owner='MACLEAN'; session A: update hcc_maclean set OBJECT_NAME=OBJECT_NAME||'DBM' where rowid='AAAThuAAEAAAHTJAOI'; session B: update hcc_maclean set OBJECT_NAME=OBJECT_NAME||'DBM' where rowid='AAAThuAAEAAAHTJAOJ'; SQL> select sid,wait_event_text,BLOCKER_SID from v$wait_chains; SID WAIT_EVENT_TEXT BLOCKER_SID ---------- ---------------------------------------------------------------- ----------- 13 enq: TX - row lock contention 136 136 SQL*Net message from client ????session A block B,????HCC???update row??CU?????CU?????? SQL> alter system checkpoint; System altered. SQL> / System altered. SQL> alter system dump datafile 4 block 29897 2 ; Block header dump: 0x010074c9 Object id on Block? Y seg/obj: 0x1386e csc: 0x00.1cad7e itc: 3 flg: E typ: 1 - DATA brn: 0 bdba: 0x10074c8 ver: 0x01 opc: 0 inc: 0 exflg: 0 Itl Xid Uba Flag Lck Scn/Fsc 0x01 0xffff.000.00000000 0x00000000.0000.00 C--- 0 scn 0x0000.001cabfa 0x02 0x000a.00a.00000430 0x00c051a7.0169.17 ---- 1 fsc 0x0000.00000000 0x03 0x0000.000.00000000 0x00000000.0000.00 ---- 0 fsc 0x0000.00000000 avsp=0x14 tosp=0x14 r0_9ir2=0x0 mec_kdbh9ir2=0x0 76543210 shcf_kdbh9ir2=---------- 76543210 flag_9ir2=--R----- Archive compression: Y fcls_9ir2[0]={ } 0x16:pti[0] nrow=1 offs=0 0x1a:pri[0] offs=0x30 block_row_dump: tab 0, row 0, @0x30 tl: 8016 fb: --H-F--N lb: 0x2 cc: 1 ==>??CU??ITL 0x02 nrid: 0x010074ca.0 col 0: [8004] Compression level: 02 (Query High) Length of CU row: 8004 kdzhrh: ------PC CBLK: 1 Start Slot: 00 NUMP: 01 PNUM: 00 POFF: 7984 PRID: 0x010074ca.0 CU header: CU version: 0 CU magic number: 0x4b445a30 CU checksum: 0xf8faf86e CU total length: 8694 CU flags: NC-U-CRD-OP ncols: 15 nrows: 995 algo: 0 CU decomp length: 8487 len/value length: 100111 row pieces per row: 1 num deleted rows: 1 deleted rows: 904, START_CU: ????????????row?????: SQL> select DBMS_COMPRESSION.GET_COMPRESSION_TYPE('SCOTT','HCC_MACLEAN','AAAThuAAEAAAHTJAOk') from dual; DBMS_COMPRESSION.GET_COMPRESSION_TYPE('SCOTT','HCC_MACLEAN','AAATHUAAEAAAHTJAOK' -------------------------------------------------------------------------------- 4 COMP_NOCOMPRESS CONSTANT NUMBER := 1;COMP_FOR_OLTP CONSTANT NUMBER := 2;COMP_FOR_QUERY_HIGH CONSTANT NUMBER := 4;COMP_FOR_QUERY_LOW CONSTANT NUMBER := 8;COMP_FOR_ARCHIVE_HIGH CONSTANT NUMBER := 16;COMP_FOR_ARCHIVE_LOW CONSTANT NUMBER := 32; COMP_RATIO_MINROWS CONSTANT NUMBER := 1000000;COMP_RATIO_ALLROWS CONSTANT NUMBER := -1; ?????????????,??COMP_FOR_QUERY_HIGH?4,COMP_FOR_QUERY_LOW ?8 ?????????GET_COMPRESSION_TYPE??rowid????????4?????COMP_FOR_QUERY_HIGH????: SQL> update hcc_maclean set OBJECT_NAME=OBJECT_NAME||'DBM' where owner='MACLEAN'; 8 rows updated. SQL> commit; Commit complete. SQL> select DBMS_COMPRESSION.GET_COMPRESSION_TYPE('SCOTT','HCC_MACLEAN',rowid) from HCC_MACLEAN where owner='MACLEAN'; DBMS_COMPRESSION.GET_COMPRESSION_TYPE('SCOTT','HCC_MACLEAN',ROWID) ------------------------------------------------------------------ 1 1 1 1 1 1 1 1 8 rows selected. ??????????????COMPRESSION_TYPE?COMP_FOR_QUERY_HIGH???COMP_NOCOMPRESS,????????compress for query high????????????????? ?11g????????????????????HCC??????????? ALTER TABLE MOVE???????????????????HCC??? SQL> ALTER TABLE hcc_MACLEAN move COMPRESS FOR ARCHIVE HIGH; Table altered. SQL> select DBMS_COMPRESSION.GET_COMPRESSION_TYPE('SCOTT','HCC_MACLEAN',rowid) from HCC_MACLEAN where owner='MACLEAN'; DBMS_COMPRESSION.GET_COMPRESSION_TYPE('SCOTT','HCC_MACLEAN',ROWID) ------------------------------------------------------------------ 16 16 16 16 16 16 16 16 8 rows selected.

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• Coherence Data Guarantees for Data Reads - Basic Terminology

  - by jpurdy

  When integrating Coherence into applications, each application has its own set of requirements with respect to data integrity guarantees. Developers often describe these requirements using expressions like "avoiding dirty reads" or "making sure that updates are transactional", but we often find that even in a small group of people, there may be a wide range of opinions as to what these terms mean. This may simply be due to a lack of familiarity, but given that Coherence sits at an intersection of several (mostly) unrelated fields, it may be a matter of conflicting vocabularies (e.g. "consistency" is similar but different in transaction processing versus multi-threaded programming). Since almost all data read consistency issues are related to the concept of concurrency, it is helpful to start with a definition of that, or rather what it means for two operations to be concurrent. Rather than implying that they occur "at the same time", concurrency is a slightly weaker statement -- it simply means that it can't be proven that one event precedes (or follows) the other. As an example, in a Coherence application, if two client members mutate two different cache entries sitting on two different cache servers at roughly the same time, it is likely that one update will precede the other by a significant amount of time (say 0.1ms). However, since there is no guarantee that all four members have their clocks perfectly synchronized, and there is no way to precisely measure the time it takes to send a given message between any two members (that have differing clocks), we consider these to be concurrent operations since we can not (easily) prove otherwise. So this leads to a question that we hear quite frequently: "Are the contents of the near cache always synchronized with the underlying distributed cache?". It's easy to see that if an update on a cache server results in a message being sent to each near cache, and then that near cache being updated that there is a window where the contents are different. However, this is irrelevant, since even if the application reads directly from the distributed cache, another thread update the cache before the read is returned to the application. Even if no other member modifies a cache entry prior to the local near cache entry being updated (and subsequently read), the purpose of reading a cache entry is to do something with the result, usually either displaying for consumption by a human, or by updating the entry based on the current state of the entry. In the former case, it's clear that if the data is updated faster than a human can perceive, then there is no problem (and in many cases this can be relaxed even further). For the latter case, the application must assume that the value might potentially be updated before it has a chance to update it. This almost aways the case with read-only caches, and the solution is the traditional optimistic transaction pattern, which requires the application to explicitly state what assumptions it made about the old value of the cache entry. If the application doesn't want to bother stating those assumptions, it is free to lock the cache entry prior to reading it, ensuring that no other threads will mutate the entry, a pessimistic approach. The optimistic approach relies on what is sometimes called a "fuzzy read". In other words, the application assumes that the read should be correct, but it also acknowledges that it might not be. (I use the qualifier "sometimes" because in some writings, "fuzzy read" indicates the situation where the application actually sees an original value and then later sees an updated value within the same transaction -- however, both definitions are roughly equivalent from an application design perspective). If the read is not correct it is called a "stale read". Going back to the definition of concurrency, it may seem difficult to precisely define a stale read, but the practical way of detecting a stale read is that is will cause the encompassing transaction to roll back if it tries to update that value. The pessimistic approach relies on a "coherent read", a guarantee that the value returned is not only the same as the primary copy of that value, but also that it will remain that way. In most cases this can be used interchangeably with "repeatable read" (though that term has additional implications when used in the context of a database system). In none of cases above is it possible for the application to perform a "dirty read". A dirty read occurs when the application reads a piece of data that was never committed. In practice the only way this can occur is with multi-phase updates such as transactions, where a value may be temporarily update but then withdrawn when a transaction is rolled back. If another thread sees that value prior to the rollback, it is a dirty read. If an application uses optimistic transactions, dirty reads will merely result in a lack of forward progress (this is actually one of the main risks of dirty reads -- they can be chained and potentially cause cascading rollbacks). The concepts of dirty reads, fuzzy reads, stale reads and coherent reads are able to describe the vast majority of requirements that we see in the field. However, the important thing is to define the terms used to define requirements. A quick web search for each of the terms in this article will show multiple meanings, so I've selected what are generally the most common variations, but it never hurts to state each definition explicitly if they are critical to the success of a project (many applications have sufficiently loose requirements that precise terminology can be avoided).

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• Can't control connection bit rate using iwconfig with Atheros TL-WN821N (AR7010)

  - by Paul H

  I'm trying to reduce the connection bit rate on my Atheros TP-Link TL-WN821N v3 usb wifi adapter due to frequent instability issues (reported connection speed goes down to 1Mb/s and I have to physically reconnect the adapter to regain a connection). I know this is a common problem with this device, and I have tried everything I can think of to fix it, including using drivers from linux-backports; compiling and installing a custom firmware (following instructions on https://wiki.debian.org/ath9k_htc#fw-free) and (as a last resort) using ndiswrapper. When using ndiswrapper, the wifi adapter is stable and operates in g mode at 54Mb/s (whilst when using the default ath9k_htc module, the adapter connects in n mode and the bit rate fluctuates constantly). Unfortunately, with this setup I have to run my processor using only one core, since using SMP with ndiswrapper causes a kernel oops on my system. So I want to lock my bit rate to 54Mb/s (or less, if need be) for connection stability, using the ath9k_htc module. I've tried 'sudo iwconfig wlan0 rate 54M'; the command runs with no error but when I check the bit rate with 'sudo iwlist wlan0 bitrate' the command returns: wlan0 unknown bit-rate information. Current Bit Rate:78 Mb/s Any ideas? Here's some info (hopefully relevant) on my setup: Xubuntu (12.04.3) 64bit (kernel 3.2.0-55.85-generic) using Network Manager. My Router is from Virgin Media, the VMDG480. lshw -C network : *-network description: Wireless interface physical id: 1 bus info: usb@1:4 logical name: wlan0 serial: 74:ea:3a:8f:16:b6 capabilities: ethernet physical wireless configuration: broadcast=yes driver=ath9k_htc driverversion=3.2.0-55 firmware=1.3 ip=192.168.0.9 link=yes multicast=yes wireless=IEEE 802.11bgn lsusb -v: Bus 001 Device 003: ID 0cf3:7015 Atheros Communications, Inc. TP-Link TL-WN821N v3 802.11n [Atheros AR7010+AR9287] Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 255 Vendor Specific Class bDeviceSubClass 255 Vendor Specific Subclass bDeviceProtocol 255 Vendor Specific Protocol bMaxPacketSize0 64 idVendor 0x0cf3 Atheros Communications, Inc. idProduct 0x7015 TP-Link TL-WN821N v3 802.11n [Atheros AR7010+AR9287] bcdDevice 2.02 iManufacturer 16 ATHEROS iProduct 32 UB95 iSerial 48 12345 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 60 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 0 bmAttributes 0x80 (Bus Powered) MaxPower 500mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 6 bInterfaceClass 255 Vendor Specific Class bInterfaceSubClass 0 bInterfaceProtocol 0 iInterface 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x82 EP 2 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x83 EP 3 IN bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0040 1x 64 bytes bInterval 1 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x04 EP 4 OUT bmAttributes 3 Transfer Type Interrupt Synch Type None Usage Type Data wMaxPacketSize 0x0040 1x 64 bytes bInterval 1 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x05 EP 5 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x06 EP 6 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 255 Vendor Specific Class bDeviceSubClass 255 Vendor Specific Subclass bDeviceProtocol 255 Vendor Specific Protocol bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0000 (Bus Powered) iwlist wlan0 scanning: wlan0 Scan completed : Cell 01 - Address: C4:3D:C7:3A:1F:5D Channel:1 Frequency:2.412 GHz (Channel 1) Quality=37/70 Signal level=-73 dBm Encryption key:on ESSID:"my essid" Bit Rates:1 Mb/s; 2 Mb/s; 5.5 Mb/s; 11 Mb/s; 18 Mb/s 24 Mb/s; 36 Mb/s; 54 Mb/s Bit Rates:6 Mb/s; 9 Mb/s; 12 Mb/s; 48 Mb/s Mode:Master Extra:tsf=00000070cca77186 Extra: Last beacon: 5588ms ago IE: Unknown: 0007756E69636F726E IE: Unknown: 010882848B962430486C IE: Unknown: 030101 IE: Unknown: 2A0100 IE: Unknown: 2F0100 IE: IEEE 802.11i/WPA2 Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: Unknown: 32040C121860 IE: Unknown: 2D1AFC181BFFFF000000000000000000000000000000000000000000 IE: Unknown: 3D1601080400000000000000000000000000000000000000 IE: Unknown: DD7E0050F204104A0001101044000102103B00010310470010F99C335D7BAC57FB00137DFA79600220102100074E657467656172102300074E6574676561721024000631323334353610420007303030303030311054000800060050F20400011011000743473331303144100800022008103C0001011049000600372A000120 IE: Unknown: DD090010180203F02C0000 IE: WPA Version 1 Group Cipher : TKIP Pairwise Ciphers (2) : CCMP TKIP Authentication Suites (1) : PSK IE: Unknown: DD180050F2020101800003A4000027A4000042435E0062322F00 iwconfig: lo no wireless extensions. wlan0 IEEE 802.11bgn ESSID:"my essid" Mode:Managed Frequency:2.412 GHz Access Point: C4:3D:C7:3A:1F:5D Bit Rate=78 Mb/s Tx-Power=20 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=36/70 Signal level=-74 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:0 Missed beacon:0,

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• Visual Studio build fails: unable to copy exe-file from obj\debug to bin\debug

  - by Nailuj

  This is a question asked before, both here on Stack Overflow and other places, but none of the suggestions I've found this far has helped me, so I just have to try asking a new question. Scenario: I have a simple Windows Forms application (C#, .NET 4.0, Visual Studio 2010). It has a couple of base forms that most other forms inherit from, it uses Entity Framework (and POCO classes) for database access. Nothing fancy, no multi-threading or anything. Problem: All was fine for a while. Then, all out of the blue, Visual Studio failed to build when I was about to launch the application. I got the warning "Unable to delete file '...bin\Debug\[ProjectName].exe'. Access to the path '...bin\Debug\[ProjectName].exe' is denied." and the error "Unable to copy file 'obj\x86\Debug\[ProjectName].exe' to 'bin\Debug\[ProjectName].exe'. The process cannot access the file 'bin\Debug\[ProjectName].exe' because it is being used by another process." (I get both the warning and the error when running Rebuild, but only the error when running Build - don't think that is relevant?) I understand perfectly fine what the warning and error message says: Visual Studio is obviously trying to overwrite the exe-file while it the same time has a lock on it for some reason. However, this doesn't help me find a solution to the problem... The only thing I've found working is to shut down Visual Studio and start it again. Building and launching then works, untill I make a change in some of the forms, then I have the same problem again and have to restart... Quite frustrating! As I mentioned above, this seems to be a known problem, so there are lots of suggested solutions. I'll just list what I've already tried here, so people know what to skip: Creating a new clean solution and just copy the files from the old solution. Adding the following to the following to the project's pre-build event: if exist "$(TargetPath).locked" del "$(TargetPath).locked"   if not exist "$(TargetPath).locked" if exist "$(TargetPath)" move "$(TargetPath)" "$(TargetPath).locked" Adding the following to the project properties (.csproj file): <GenerateResourceNeverLockTypeAssembliestrue</GenerateResourceNeverLockTypeAssemblies However, none of them worked for me, so you can probably see why I'm starting to get a bit frustrated. I don't know where else to look, so I hope somebody has something to give me! Is this a bug in VS, and if so is there a patch? Or has I done something wrong, do I have a circular reference or similar, and if so how could I find out? Any suggestions are highly appreciated :)

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• DirectoryServicesCOMException when working with System.DirectoryServices.AccountManagement

  - by antik

  I'm attempting to determine whether a user is a member of a given group using System.DirectoryServices.AccountManagment. I'm doing this inside a SharePoint WebPart in SharePoint 2007 on a 64-bit system. Project targets .NET 3.5 Impersonation is enabled in the web.config. The IIS Site in question is using an IIS App Pool with a domain user configured as the identity. I am able to instantiate a PrincipalContext as such: PrincipalContext pc = new PrincipalContext(ContextType.Domain) Next, I try to grab a principal: using (PrincipalContext pc = new PrincipalContext(ContextType.Domain)) { GroupPrincipal group = GroupPrincipal.FindByIdentity(pc, "MYDOMAIN\somegroup"); // snip: exception thrown by line above. } Both the above and UserPrincipal.FindByIdentity with a user SAM throw a DirectoryServicesCOMException: "Logon failure: Unknown user name or bad password" I've tried passing in a complete SAMAccountName to either FindByIdentity (in the form of MYDOMAIN\username) or just the username with no change in behavior. I've tried executing the code with other credentials using both the HostingEnvironment.Impersonate and SPSecurity.RunWithElevatedPrivileges approaches and also experience the same result. I've also tried instantiating my context with the domain name in place: Principal Context pc = new PrincipalContext(ContextType.Domain, "MYDOMAIN"); This throws a PrincipalServerDownException: "The server could not be contacted." I'm working on a reasonably hardened server. I did not lock the system down so I am unsure exactly what has been done to it. If there are credentials I need to allocate to my pool identity's user or in the domain security policy in order for these to work, I can configure the domain accordingly. Are there any settings that would be preventing my code from running? Am I missing something in the code itself? Is this just not possible in a SharePoint web? EDIT: Given further testing, my code functions correctly when tested in a Console application targeting .NET 4.0. I targeted a different framework because I didn't have AccountManagement available to me in the console app when targeting .NET 3.5 for some reason. using (PrincipalContext pc = new PrincipalContext(ContextType.Domain)) using (UserPrincipal adUser = UserPrincipal.FindByIdentity(pc, "MYDOMAIN\joe.user")) using (GroupPrincipal adGroup = GroupPrincipal.FindByIdentity(pc, "MYDOMAIN\user group")) { if (adUser.IsMemberOf(adGroup)) { Console.WriteLine("User is a member!"); } else { Console.WriteLine("User is NOT a member."); } } What varies in my SharePoint environment that might prohibit this function from executing?

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• How do I use PackageManager.addPreferredActivity()?

  - by afonseca

  In SDK 1.5 I was using the PackageManager class to set the preferred home screen to be my app using PackageManager.addPackageToPreferred(). In the new SDK (using 2.1) this has been deprecated so I'm trying to use addPreferredActivity() for the same result but it's not working as expected. Some necessary background. I'm writing a lock screen replacement app so I want the home key to launch my app (which will already be running, hence having the effect of disabling the key). When the user "unlocks" the screen I intend to restore the mapping so everything works as normal. In my AndroidManifest.xml I have: <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> <category android:name="android.intent.category.HOME"/> <category android:name="android.intent.category.DEFAULT" /> </intent-filter> <uses-permission android:name="android.permission.SET_PREFERRED_APPLICATIONS"> </uses-permission> In my code I have the following snippet: // Set as home activity // This is done so we can appear to disable the Home key. PackageManager pm = getPackageManager(); //pm.addPackageToPreferred(getPackageName()); IntentFilter filter = new IntentFilter("android.intent.action.MAIN"); filter.addCategory("android.intent.category.HOME"); filter.addCategory("android.intent.category.DEFAULT"); ComponentName[] components = new ComponentName[] { new ComponentName("com.android.launcher", ".Launcher") }; Context context = getApplicationContext(); ComponentName component = new ComponentName(context.getPackageName(), MyApp.class.getName()); pm.clearPackagePreferredActivities("com.android.launcher"); pm.addPreferredActivity(filter, IntentFilter.MATCH_CATEGORY_EMPTY, components, component); The resulting behavior is that the app chooser comes up when I press the Home key, which indicates that the clearPackagePreferredActivities() call worked but my app did not get added as the preferred. Also, the first line in the log below says something about "dropping preferred activity for Intent": 04-06 02:34:42.379: INFO/PackageManager(1017): Result set changed, dropping preferred activity for Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10200000 } type null 04-06 02:34:42.379: INFO/ActivityManager(1017): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10200000 cmp=android/com.android.internal.app.ResolverActivity } Does anyone know what this first log message means? Maybe I'm not using the API correctly, any ideas? Any help would be greatly appreciated.

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• ensime scala errors (class scala.Array not found, object scala not found)

  - by Jeff Bowman

  I've installed ensime according to the README.md file, however, I get errors in the inferior-ensime-server buffer with the following: INFO: Fatal Error: scala.tools.nsc.MissingRequirementError: object scala not found. scala.tools.nsc.MissingRequirementError: object scala not found. at scala.tools.nsc.symtab.Definitions$definitions$.getModuleOrClass(Definitions.scala:516) at scala.tools.nsc.symtab.Definitions$definitions$.ScalaPackage(Definitions.scala:43) at scala.tools.nsc.symtab.Definitions$definitions$.ScalaPackageClass(Definitions.scala:44) at scala.tools.nsc.symtab.Definitions$definitions$.UnitClass(Definitions.scala:89) at scala.tools.nsc.symtab.Definitions$definitions$.init(Definitions.scala:786) at scala.tools.nsc.Global$Run.(Global.scala:593) at scala.tools.nsc.interactive.Global$TyperRun.(Global.scala:473) at scala.tools.nsc.interactive.Global.newTyperRun(Global.scala:535) at scala.tools.nsc.interactive.Global.reloadSources(Global.scala:289) at scala.tools.nsc.interactive.Global$$anonfun$reload$1.apply(Global.scala:300) at scala.tools.nsc.interactive.Global$$anonfun$reload$1.apply(Global.scala:300) at scala.tools.nsc.interactive.Global.respond(Global.scala:276) at scala.tools.nsc.interactive.Global.reload(Global.scala:300) at scala.tools.nsc.interactive.CompilerControl$$anon$1.apply$mcV$sp(CompilerControl.scala:81) at scala.tools.nsc.interactive.Global.pollForWork(Global.scala:132) at scala.tools.nsc.interactive.Global$$anon$2.run(Global.scala:192) also: INFO: Fatal Error: scala.tools.nsc.MissingRequirementError: class scala.Array not found. scala.tools.nsc.MissingRequirementError: class scala.Array not found. at scala.tools.nsc.symtab.Definitions$definitions$.getModuleOrClass(Definitions.scala:516) at scala.tools.nsc.symtab.Definitions$definitions$.getClass(Definitions.scala:474) at scala.tools.nsc.symtab.Definitions$definitions$.ArrayClass(Definitions.scala:217) at scala.tools.nsc.backend.icode.TypeKinds$REFERENCE.(TypeKinds.scala:258) at scala.tools.nsc.backend.icode.GenICode$ICodePhase.(GenICode.scala:55) at scala.tools.nsc.backend.icode.GenICode.newPhase(GenICode.scala:43) at scala.tools.nsc.backend.icode.GenICode.newPhase(GenICode.scala:25) at scala.tools.nsc.Global$Run$$anonfun$4.apply(Global.scala:606) at scala.tools.nsc.Global$Run$$anonfun$4.apply(Global.scala:605) at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:62) at scala.collection.immutable.List.foreach(List.scala:46) at scala.tools.nsc.Global$Run.(Global.scala:605) at scala.tools.nsc.interactive.Global$TyperRun.(Global.scala:473) at scala.tools.nsc.interactive.Global.newTyperRun(Global.scala:535) at scala.tools.nsc.interactive.Global.reloadSources(Global.scala:289) at scala.tools.nsc.interactive.Global.typedTreeAt(Global.scala:309) at scala.tools.nsc.interactive.Global$$anonfun$getTypedTreeAt$1.apply(Global.scala:326) at scala.tools.nsc.interactive.Global$$anonfun$getTypedTreeAt$1.apply(Global.scala:326) at scala.tools.nsc.interactive.Global.respond(Global.scala:276) at scala.tools.nsc.interactive.Global.getTypedTreeAt(Global.scala:326) at scala.tools.nsc.interactive.CompilerControl$$anon$2.apply$mcV$sp(CompilerControl.scala:89) at scala.tools.nsc.interactive.Global.pollForWork(Global.scala:132) at scala.tools.nsc.interactive.Global$$anon$2.run(Global.scala:192) Also none of the type identification works for me, I get 'NA' if I get anything at all. C-c t causes emacs to lock up. I'm running: Ubuntu 10.04 (64bit version) emacs 23.1.50.1 ensime from git (as of 3 May 2010) scala is version 2.8.0.RC1 java is 1.6.0_20 (from sun) here is a copy of the log: http://dl.dropbox.com/u/5309017/ensime.log Thanks! Jeff

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• SQLite file locking and DropBox

  - by Alex Jenter

  I'm developing an app in Visual C++ that uses an SQLite3 DB for storing data. Usually it sits in the tray most of the time. I also would like to enable putting my app in a DropBox folder to share it across several PCs. It worked really well up until DropBox has recently updated itself. And now it says that it "can't sync the file in use". The SQLite file is open in my app, but the lock is shared. There are some prepared statements, but all are reset immediately after using step. Is there any way to enable synchronizing of an open SQLite database file? Thanks! Here is the simple wrapper that I use just for testing (no error handling), in case this helps: class Statement { private: Statement(sqlite3* db, const std::wstring& sql) : db(db) { sqlite3_prepare16_v2(db, sql.c_str(), sql.length() * sizeof(wchar_t), &stmt, NULL); } public: ~Statement() { sqlite3_finalize(stmt); } public: void reset() { sqlite3_reset(stmt); } int step() { return sqlite3_step(stmt); } int getInt(int i) const { return sqlite3_column_int(stmt, i); } tstring getText(int i) const { const wchar_t* v = (const wchar_t*)sqlite3_column_text16(stmt, i); int sz = sqlite3_column_bytes16(stmt, i) / sizeof(wchar_t); return std::wstring(v, v + sz); } private: friend class Database; sqlite3* db; sqlite3_stmt* stmt; }; class Database { public: Database(const std::wstring& filename = L"")) : db(NULL) { sqlite3_open16(filename.c_str(), &db); } ~Database() { sqlite3_close(db); } void exec(const std::wstring& sql) { auto_ptr<Statement> st(prepare(sql)); st->step(); } auto_ptr<Statement> prepare(const tstring& sql) const { return auto_ptr<Statement>(new Statement(db, sql)); } private: sqlite3* db; };

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• Can not delete row from MySQL

  - by Drew

  Howdy all, I've got a table, which won't delete a row. Specifically, when I try to delete any row with a GEO_SHAPE_ID over 150000000 it simply does not disappear from the DB. I have tried: SQLyog to erase it. DELETE FROM TABLE WHERE GEO_SHAPE_ID = 150000042 (0 rows affected). UNLOCK TABLES then 2. As far as I am aware, bigint is a valid candidate for auto_increment. Anyone know what could be up? You gotta help us, Doc. We’ve tried nothin’ and we’re all out of ideas! DJS. PS. Here is the table construct and some sample data just for giggles. CREATE TABLE `GEO_SHAPE` ( `GEO_SHAPE_ID` bigint(11) NOT NULL auto_increment, `RADIUS` float default '0', `LATITUDE` float default '0', `LONGITUDE` float default '0', `SHAPE_TYPE` enum('Custom','Region') default NULL, `PARENT_ID` int(11) default NULL, `SHAPE_POLYGON` polygon default NULL, `SHAPE_TITLE` varchar(45) default NULL, `SHAPE_ABBREVIATION` varchar(45) default NULL, PRIMARY KEY (`GEO_SHAPE_ID`) ) ENGINE=MyISAM AUTO_INCREMENT=150000056 DEFAULT CHARSET=latin1 CHECKSUM=1 DELAY_KEY_WRITE=1 ROW_FORMAT=DYNAMIC; SET FOREIGN_KEY_CHECKS = 0; LOCK TABLES `GEO_SHAPE` WRITE; INSERT INTO `GEO_SHAPE` (`GEO_SHAPE_ID`, `RADIUS`, `LATITUDE`, `LONGITUDE`, `SHAPE_TYPE`, `PARENT_ID`, `SHAPE_POLYGON`, `SHAPE_TITLE`, `SHAPE_ABBREVIATION`) VALUES (57, NULL, NULL, NULL, 'Region', 10, NULL, 'Washington', 'WA'); INSERT INTO `GEO_SHAPE` (`GEO_SHAPE_ID`, `RADIUS`, `LATITUDE`, `LONGITUDE`, `SHAPE_TYPE`, `PARENT_ID`, `SHAPE_POLYGON`, `SHAPE_TITLE`, `SHAPE_ABBREVIATION`) VALUES (58, NULL, NULL, NULL, 'Region', 10, NULL, 'West Virginia', 'WV'); INSERT INTO `GEO_SHAPE` (`GEO_SHAPE_ID`, `RADIUS`, `LATITUDE`, `LONGITUDE`, `SHAPE_TYPE`, `PARENT_ID`, `SHAPE_POLYGON`, `SHAPE_TITLE`, `SHAPE_ABBREVIATION`) VALUES (59, NULL, NULL, NULL, 'Region', 10, NULL, 'Wisconsin', 'WI'); INSERT INTO `GEO_SHAPE` (`GEO_SHAPE_ID`, `RADIUS`, `LATITUDE`, `LONGITUDE`, `SHAPE_TYPE`, `PARENT_ID`, `SHAPE_POLYGON`, `SHAPE_TITLE`, `SHAPE_ABBREVIATION`) VALUES (150000042, 10, -33.8833, 151.217, 'Custom', NULL, NULL, 'Sydney%2C%20New%20South%20Wales%20%2810km%20r', NULL); INSERT INTO `GEO_SHAPE` (`GEO_SHAPE_ID`, `RADIUS`, `LATITUDE`, `LONGITUDE`, `SHAPE_TYPE`, `PARENT_ID`, `SHAPE_POLYGON`, `SHAPE_TITLE`, `SHAPE_ABBREVIATION`) VALUES (150000043, 10, -33.8833, 151.167, 'Custom', NULL, NULL, 'Annandale%2C%20New%20South%20Wales%20%2810km%', NULL); INSERT INTO `GEO_SHAPE` (`GEO_SHAPE_ID`, `RADIUS`, `LATITUDE`, `LONGITUDE`, `SHAPE_TYPE`, `PARENT_ID`, `SHAPE_POLYGON`, `SHAPE_TITLE`, `SHAPE_ABBREVIATION`) VALUES (150000048, 10, -27.5, 153.017, 'Custom', NULL, NULL, 'Brisbane%2C%20Queensland%20%2810km%20radius%2', NULL); INSERT INTO `GEO_SHAPE` (`GEO_SHAPE_ID`, `RADIUS`, `LATITUDE`, `LONGITUDE`, `SHAPE_TYPE`, `PARENT_ID`, `SHAPE_POLYGON`, `SHAPE_TITLE`, `SHAPE_ABBREVIATION`) VALUES (150000045, 10, 43.1002, -75.2956, 'Custom', NULL, NULL, 'New%20York%20Mills%2C%20New%20York%20%2810km%', NULL); INSERT INTO `GEO_SHAPE` (`GEO_SHAPE_ID`, `RADIUS`, `LATITUDE`, `LONGITUDE`, `SHAPE_TYPE`, `PARENT_ID`, `SHAPE_POLYGON`, `SHAPE_TITLE`, `SHAPE_ABBREVIATION`) VALUES (150000046, 10, 40.1117, -78.9258, 'Custom', NULL, NULL, 'Region1', NULL); UNLOCK TABLES; SET FOREIGN_KEY_CHECKS = 1;

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• XNA - Keyboard text input

  - by Sekhat

  Okay, so basically I want to be able to retrieve keyboard text. Like entering text into a text field or something. I'm only writing my game for windows. I've disregarded using Guide.BeginShowKeyboardInput because it breaks the feel of a self contained game, and the fact that the Guide always shows XBOX buttons doesn't seem right to me either. Yes it's the easiest way, but I don't like it. Next I tried using System.Windows.Forms.NativeWindow. I created a class that inherited from it, and passed it the Games window handle, implemented the WndProc function to catch WM_CHAR (or WM_KEYDOWN) though the WndProc got called for other messages, WM_CHAR and WM_KEYDOWN never did. So I had to abandon that idea, and besides, I was also referencing the whole of Windows forms, which meant unnecessary memory footprint bloat. So my last idea was to create a Thread level, low level keyboard hook. This has been the most successful so far. I get WM_KEYDOWN message, (not tried WM_CHAR yet) translate the virtual keycode with Win32 funcation MapVirtualKey to a char. And I get my text! (I'm just printing with Debug.Write at the moment) A couple problems though. It's as if I have caps lock on, and an unresponsive shift key. (Of course it's not however, it's just that there is only one Virtual Key Code per key, so translating it only has one output) and it adds overhead as it attaches itself to the Windows Hook List and isn't as fast as I'd like it to be, but the slowness could be more due to Debug.Write. Has anyone else approached this and solved it, without having to resort to an on screen keyboard? or does anyone have further ideas for me to try? thanks in advance. note: This is cross posted from the XNA Creators Forums, so if I get an answer there I'll post it here and Vice-Versa Question asked by Jimmy Maybe I'm not understanding the question, but why can't you use the XNA Keyboard and KeyboardState classes? My comment: It's because though you can read keystates, you can't get access to typed text as and how it is typed by the user. So let me further clarify. I want to implement being able to read text input from the user as if they are typing into textbox is windows. The keyboard and KeyboardState class get states of all keys, but I'd have to map each key and combination to it's character representation. This falls over when the user doesn't use the same keyboard language as I do especially with symbols (my double quotes is shift + 2, while american keyboards have theirs somewhere near the return key).

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• Why not .NET-style delegates rather than closures in Java?

  - by h2g2java

  OK, this is going to be my beating a dying horse for the 3rd time. However, this question is different from my earlier two about closures/delegates, which asks about plans for delegates and what are the projected specs and implementation for closures. This question is about - why is the Java community struggling to define 3 different types of closures when we could simply steal the whole concept of delegates lock, stock and barrel from our beloved and friendly neighbour - Microsoft. There are two non-technical conclusions I would be very tempted to jump into: The Java community should hold up its pride, at the cost of needing to go thro convoluted efforts, by not succumbing to borrowing any Microsoft concepts or otherwise vindicate Microsoft's brilliance. Delegates is a Microsoft patented technology. Alright, besides the above two possibilities, Q1. Is there any weakness or inadequacy in msft-styled delegates that the three (or more) forms of closures would be addressing? Q2. I am asking this while shifting between java and c# and it intrigues me that c# delegates does exactly what I needed. Are there features that would be implemented in closures that are not currently available in C# delegates? If so what are they because I cannot see what I need more than what C# delegates has adequately provided me? Q3. I know that one of the concerns about implementing closures/delegates in java is the reduction of orthogonality of the language, where more than one way is exposed to perform a particular task. Is it worth the level convolution and time spent to avoid delegates just to ensure java retains its level of orthogonality? In SQL, we know that it is advisable to break orthogonality by frequently adequately satisfying only the 2nd normal form. Why can't java be subjected to reduction of orthogonality and OO-ness for the sake of simplicity? Q4. The architecture of JVM is technically constrained from implementing .NET-styled delegates. If this reason WERE (subjunctive to emphasize unlikelihood) true, then why can't the three closures proposals be hidden behind a simple delegate keyword or annotation: if we don't like to use @delegate, we could use @method. I cannot see how delegate statement format is more complex than the three closure proposals.

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• How to GET a read-only vs editable resource in REST style?

  - by Val

  I'm fairly familiar with REST principles, and have read the relevant dissertation, Wikipedia entry, a bunch of blog posts and StackOverflow questions on the subject, but still haven't found a straightforward answer to a common case: I need to request a resource to display. Depending on the resource's state, I need to render either a read-only or an editable representation. In both cases, I need to GET the resource. How do I construct a URL to get the read-only or editable version? If my user follows a link to GET /resource/<id>, that should suffice to indicate to me that s/he needs the read-only representation. But if I need to server up an editable form, what does that URL look like? GET /resource/<id>/edit is obvious, but it contains a verb in the URL. Changing that to GET /resource/<id>/editable solves that problem, but at a seemingly superficial level. Is that all there is to it -- change verbs to adjectives? If instead I use POST to retrieve the editable version, then how do I distinguish between the POST that initially retrieves it, vs the POST that saves it? My (weak) excuse for using POST would be that retrieving an editable version would cause a change of state on the server: locking the resource. But that only holds if my requirements are to implement such a lock, which is not always the case. PUT fails for the same reason, plus PUT is not enabled by default on the Web servers I'm running, so there are practical reasons not to use it (and DELETE). Note that even in the editable state, I haven't made any changes yet; presumably when I submit the resource to the Web server again, I'd POST it. But to get something that I can later POST, the server has to first serve up a particular representation. I guess another approach would be to have separate resources at the collection level: GET /read-only/resource/<id> and GET /editable/resource/<id> or GET /resource/read-only/<id> and GET /resource/editable/<id> ... but that looks pretty ugly to me. Thoughts?

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• SQLCMD Restore works in Management Studio but not from DOS prompt

  - by Gautam

  Any idea why my Restore command works fine when run in Management Studio 2008 but not when run from the dos prompt? Shown below is the error when running from the dos prompt. C:\>SQLCMD -s local\SQL2008 -d master -Q "RESTORE DATABASE [Sample.Db] FROM DISK = N'C:\Sample.Db.bak' WITH FILE = 1, MOVE N'Sample.Db' TO N'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\Sample.Db.mdf', MOVE N'Sample.Db_log' TO N'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\Sample.Db_log.ldf', NOUNLOAD, REPLACE, STATS = 10" Msg 3634, Level 16, State 1, Server GAUTAM, Line 1 The operating system returned the error '32(The process cannot access the file because it is being used by another process.)' while attempting 'RestoreContainer::ValidateTargetForCreation' on 'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\Sample.Db.mdf'. Msg 3156, Level 16, State 8, Server GAUTAM, Line 1 File 'Sample.Db' cannot be restored to 'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\Sample.Db.mdf'. Use WITH MOVE to identify a valid location for the file. Msg 3634, Level 16, State 1, Server GAUTAM, Line 1 The operating system returned the error '32(The process cannot access the file because it is being used by another process.)' while attempting 'RestoreContainer::ValidateTargetForCreation' on 'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\Sample.Db_log.ldf'. Msg 3156, Level 16, State 8, Server GAUTAM, Line 1 File 'Sample.Db_log' cannot be restored to 'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\Sample.Db_log.ldf'. Use WITH MOVE to identify a valid location for the file. Msg 3119, Level 16, State 1, Server GAUTAM, Line 1 Problems were identified while planning for the RESTORE statement. Previous messages provide details. Msg 3013, Level 16, State 1, Server GAUTAM, Line 1 RESTORE DATABASE is terminating abnormally. However if I execute this directly in Management Studio 2008, it works fine: RESTORE DATABASE [Sample.Db] FROM DISK = N'C:\Sample.Db.bak' WITH FILE = 1, MOVE N'Sample.Db' TO N'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\Sample.Db.mdf', MOVE N'Sample.Db_log' TO N'C:\Program Files\Microsoft SQL Server\MSSQL10.SQL2008\MSSQL\DATA\Sample.Db_log.ldf', NOUNLOAD, REPLACE, STATS = 10 There is no lock or security issues, the data base doesn't exist on the server. I can't figure it out. Any ideas?

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• Problems doing asynch operations in C# using Mutex.

  - by firoso

  I've tried this MANY ways, here is the current iteration. I think I've just implemented this all wrong. What I'm trying to accomplish is to treat this Asynch result in such a way that until it returns AND I finish with my add-thumbnail call, I will not request another call to imageProvider.BeginGetImage. To Clarify, my question is two-fold. Why does what I'm doing never seem to halt at my Mutex.WaitOne() call, and what is the proper way to handle this scenario? /// <summary> /// re-creates a list of thumbnails from a list of TreeElementViewModels (directories) /// </summary> /// <param name="list">the list of TreeElementViewModels to process</param> public void BeginLayout(List<AiTreeElementViewModel> list) { // *removed code for canceling and cleanup from previous calls* // Starts the processing of all folders in parallel. Task.Factory.StartNew(() => { thumbnailRequests = Parallel.ForEach<AiTreeElementViewModel>(list, options, ProcessFolder); }); } /// <summary> /// Processes a folder for all of it's image paths and loads them from disk. /// </summary> /// <param name="element">the tree element to process</param> private void ProcessFolder(AiTreeElementViewModel element) { try { var images = ImageCrawler.GetImagePaths(element.Path); AsyncCallback callback = AddThumbnail; foreach (var image in images) { Console.WriteLine("Attempting Enter"); synchMutex.WaitOne(); Console.WriteLine("Entered"); var result = imageProvider.BeginGetImage(callback, image); } } catch (Exception exc) { Console.WriteLine(exc.ToString()); // TODO: Do Something here. } } /// <summary> /// Adds a thumbnail to the Browser /// </summary> /// <param name="result">an async result used for retrieving state data from the load task.</param> private void AddThumbnail(IAsyncResult result) { lock (Thumbnails) { try { Stream image = imageProvider.EndGetImage(result); string filename = imageProvider.GetImageName(result); string imagePath = imageProvider.GetImagePath(result); var imageviewmodel = new AiImageThumbnailViewModel(image, filename, imagePath); thumbnailHash[imagePath] = imageviewmodel; HostInvoke(() => Thumbnails.Add(imageviewmodel)); UpdateChildZoom(); //synchMutex.ReleaseMutex(); Console.WriteLine("Exited"); } catch (Exception exc) { Console.WriteLine(exc.ToString()); // TODO: Do Something here. } } }

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• Subclassing a window from a thread in c#

  - by user258651

  I'm creating a thread that looks for a window. When it finds the window, it overrides its windowproc, and handles WM_COMMAND and WM_CLOSE. Here's the code that looks for the window and subclasses it: public void DetectFileDialogProc() { Window fileDialog = null; // try to find the dialog twice, with a delay of 500 ms each time for (int attempts = 0; fileDialog == null && attempts < 2; attempts++) { // FindDialogs enumerates all windows of class #32770 via an EnumWindowProc foreach (Window wnd in FindDialogs(500)) { IntPtr parent = NativeMethods.User32.GetParent(wnd.Handle); if (parent != IntPtr.Zero) { // we're looking for a dialog whose parent is a dialog as well Window parentWindow = new Window(parent); if (parentWindow.ClassName == NativeMethods.SystemWindowClasses.Dialog) { fileDialog = wnd; break; } } } } // if we found the dialog if (fileDialog != null) { OldWinProc = NativeMethods.User32.GetWindowLong(fileDialog.Handle, NativeMethods.GWL_WNDPROC); NativeMethods.User32.SetWindowLong(fileDialog.Handle, NativeMethods.GWL_WNDPROC, Marshal.GetFunctionPointerForDelegate(new WindowProc(WndProc)).ToInt32()); } } And the windowproc: public IntPtr WndProc(IntPtr hWnd, uint msg, IntPtr wParam, IntPtr lParam) { lock (this) { if (!handled) { if (msg == NativeMethods.WM_COMMAND || msg == NativeMethods.WM_CLOSE) { // adding to a list. i never access the window via the hwnd from this list, i just treat it as a number _addDescriptor(hWnd); handled = true; } } } return NativeMethods.User32.CallWindowProc(OldWinProc, hWnd, msg, wParam, lParam); } This all works well under normal conditions. But I am seeing two instances of bad behavior in order of badness: If I do not close the dialog within a minute or so, the app crashes. Is this because the thread is getting garbage collected? This would kind of make sense, as far as GC can tell the thread is done? If this is the case, (and I don't know that it is), how can I make the thread stay around as long as the dialog is around? If I immediately close the dialog with the 'X' button (WM_CLOSE) the app crashes. I believe its crashing in the windowproc, but I can't get a breakpoint in there. I'm getting an AccessViolationException, The exception says "Attempted to read or write protected memory. This is often an indication that other memory is corrupt." Its a race condition, but of what I don't know. FYI, I had been reseting the old windowproc once I processed the commands, but that was crashing even more often! Any ideas on how I can solve these issues?

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