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• Resolve Wrong IP from Domain Name only on certain networks

  - by Godric Seer

  I host a personal website on an old desktop that is LAMP based. There are several strange things about this problem so I will break it down into steps. Since I have a dynamic IP, I use no-ip to make sure I have a working domain name at all times. I use the automatic update client, but logged in and checked and my no-ip domain has the proper IP tied to it. Here is a link to the homepage through the no-ip domain for reference. Also, I do a ping and a traceroute on the no-ip domain and get: [eckertzs@localhost ~]$ ping -c 1 endradil.noip.me PING endradil.noip.me (65.24.215.99) 56(84) bytes of data. 64 bytes from endradil.noip.me (65.24.215.99): icmp_seq=1 ttl=64 time=2.23 ms --- endradil.noip.me ping statistics --- 1 packets transmitted, 1 received, 0% packet loss, time 104ms rtt min/avg/max/mdev = 2.233/2.233/2.233/0.000 ms [eckertzs@localhost ~]$ traceroute endradil.noip.me traceroute to endradil.noip.me (65.24.215.99), 30 hops max, 60 byte packets 1 . (192.168.2.1) 1.755 ms 5.409 ms 5.380 ms 2 endradil.noip.me (65.24.215.99) 6.297 ms 9.543 ms 10.324 ms Using this domain, I can connect to my webserver without issue or interruption(the https is required to avoid a redirect serverside, but it works). I also have a domain I have bought on GoDaddy where I have a CNAME record forwarding the www subdomain to my no-ip domain. CNAME Record Host: www Points to: endradil.noip.me TTL: 1 hour For the past several weeks, I never had an issue using the GoDaddy domain to connect (ssh or https). As of the past few days, however, the GoDaddy domain has only worked intermittently, for a few minutes at a time and then will go down for hours at a time. I get server not found errors most of the time. Also, if I happen to be using the GoDaddy domain for an ssh connection, the connection will freeze. I have run online tests of the DNS and have seen that the website is visible by external servers and resolved to the correct IP. I also contacted GoDaddy support but they had no issues connecting to the website, and therefore did not see any issues. My personal computers (Windows desktop, linux laptop, android phone) all fail to connect when on my personal wifi. If I disconnect my phone from the wifi and use my AT&T wireless data, it can connect with both domains without issue. When I attempt to use Google webmaster tools to crawl the site using the GoDaddy domain, Google can not find the site. From my linux laptop, I have found some interesting results when I ping or traceroute the domain. The results from these: [eckertzs@localhost ~]$ ping -c 1 www.endradil.com PING www.endradil.com.Belkin (198.105.244.228) 56(84) bytes of data. --- www.endradil.com.Belkin ping statistics --- 1 packets transmitted, 0 received, 100% packet loss, time 10000ms [eckertzs@localhost ~]$ traceroute www.endradil.com traceroute to www.endradil.com (198.105.244.228), 30 hops max, 60 byte packets 1 . (192.168.2.1) 1.918 ms 2.806 ms 2.772 ms 2 cpe-65-24-208-1.insight.res.rr.com (65.24.208.1) 29.247 ms 29.654 ms 30.094 ms 3 cpe-69-23-24-117.new.res.rr.com (69.23.24.117) 15.597 ms 23.218 ms 23.581 ms 4 agg24.clmcohib01r.midwest.rr.com (65.29.1.52) 30.581 ms 30.556 ms 31.192 ms 5 be27.clevohek01r.midwest.rr.com (65.29.1.38) 30.580 ms 31.062 ms 31.038 ms 6 bu-ether25.atlngamq47w-bcr01.tbone.rr.com (107.14.19.38) 37.863 ms 68.844 ms 43.773 ms 7 107.14.17.178 (107.14.17.178) 51.866 ms 51.019 ms 50.989 ms 8 ae0.pr1.dca10.tbone.rr.com (107.14.17.200) 48.467 ms ae-4-0.a0.lax91.tbone.rr.com (66.109.1.113) 49.912 ms * 9 v413.core1.ash1.he.net (209.51.175.33) 60.270 ms 50.842 ms 50.819 ms 10 100ge5-1.core1.nyc4.he.net (184.105.223.166) 55.597 ms 56.045 ms 56.020 ms 11 xerocole-inc.10gigabitethernet12-4.core1.nyc4.he.net (216.66.41.242) 56.001 ms 55.969 ms 55.992 ms 12 * * * both show the incorrect IP. Also, the traceroute timesout on hops 12 through 255 (output truncated above). The traceroute using site24x7 works and shows reasonable results when run from their california server. From another linux box on a different network but in the same city as me (10 miles away), I still get timeout for traceroute, however the IP resolves correctly for the domain. From this I believe that the DNS result is incorrectly cached in either my router/modem or perhaps even at my ISP level. My question is, first, how do I find out exactly what is wrong, and second, how do I resolve it.

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• Server hung with "blocked for more than 120 seconds", diskless

  - by alterpub

  I have server which hung every 2-5 days. dmesg show following situation: kernel: [490894.231753] INFO: task munin-html:10187 blocked for more than 120 seconds. kernel: [490894.231799] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kernel: [490894.231843] munin-html D 0000000000000000 0 10187 9796 0x00000000 kernel: [490894.231878] ffff88063174b968 0000000000000082 ffff88063174b8d8 0000000000015b80 kernel: [490894.231930] ffff88063174bfd8 0000000000015b80 ffff88063174bfd8 ffff88062fe644d0 kernel: [490894.231982] 0000000000015b80 0000000000015b80 ffff88063174bfd8 0000000000015b80 kernel: [490894.232033] Call Trace: kernel: [490894.232059] [<ffffffff8117fce0>] ? sync_buffer+0x0/0x50 kernel: [490894.232089] [<ffffffff815a1f13>] io_schedule+0x73/0xc0 kernel: [490894.232115] [<ffffffff8117fd25>] sync_buffer+0x45/0x50 kernel: [490894.232143] [<ffffffff815a258f>] __wait_on_bit+0x5f/0x90 kernel: [490894.232170] [<ffffffff8117fce0>] ? sync_buffer+0x0/0x50 kernel: [490894.232197] [<ffffffff815a2638>] out_of_line_wait_on_bit+0x78/0x90 kernel: [490894.232227] [<ffffffff81080250>] ? wake_bit_function+0x0/0x40 kernel: [490894.232255] [<ffffffff8117fcd6>] __wait_on_buffer+0x26/0x30 kernel: [490894.232288] [<ffffffffa00131be>] squashfs_read_data+0x1be/0x520 [squashfs] kernel: [490894.232320] [<ffffffff8114f0f1>] ? __mem_cgroup_try_charge+0x71/0x450 kernel: [490894.232350] [<ffffffffa0013963>] squashfs_cache_get+0x1c3/0x320 [squashfs] kernel: [490894.232381] [<ffffffffa00136eb>] ? squashfs_copy_data+0x10b/0x130 [squashfs] kernel: [490894.232426] [<ffffffff815a3dbe>] ? _raw_spin_lock+0xe/0x20 kernel: [490894.232454] [<ffffffffa0013b68>] ? squashfs_read_metadata+0x48/0xf0 [squashfs] kernel: [490894.232499] [<ffffffffa0013ae1>] squashfs_get_datablock+0x21/0x30 [squashfs] kernel: [490894.232544] [<ffffffffa0015026>] squashfs_readpage+0x436/0x4a0 [squashfs] kernel: [490894.232575] [<ffffffff8111a375>] ? __inc_zone_page_state+0x35/0x40 kernel: [490894.232606] [<ffffffff8110d072>] __do_page_cache_readahead+0x172/0x210 kernel: [490894.232636] [<ffffffff8110d131>] ra_submit+0x21/0x30 kernel: [490894.232662] [<ffffffff811045f3>] filemap_fault+0x3f3/0x450 kernel: [490894.232691] [<ffffffff812bd156>] ? prio_tree_insert+0x256/0x2b0 kernel: [490894.232726] [<ffffffffa009225d>] aufs_fault+0x11d/0x170 [aufs] kernel: [490894.232755] [<ffffffff8111f6d4>] __do_fault+0x54/0x560 kernel: [490894.232782] [<ffffffff81122f39>] handle_mm_fault+0x1b9/0x440 kernel: [490894.232811] [<ffffffff811286f5>] ? do_mmap_pgoff+0x335/0x380 kernel: [490894.232840] [<ffffffff815a7af5>] do_page_fault+0x125/0x350 kernel: [490894.232867] [<ffffffff815a4675>] page_fault+0x25/0x30 Os info cat /etc/issue.net Ubuntu 10.04.2 LTS uname -a Linux Shard1Host3 2.6.35-32-server #68~lucid1-Ubuntu SMP Wed Mar 28 18:33:00 UTC 2012 x86_64 GNU/Linux This system load via ltsp and hasn't harddrives also it has a lot of memory 24Gb. free -m total used free shared buffers cached Mem: 24152 17090 7061 0 50 494 -/+ buffers/cache: 16545 7607 Swap: 0 0 0 I put vmstat info here but I think it won't give results after reboot vmstat 1 30 procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 7231156 52196 506400 0 0 0 0 172 143 7 0 92 0 1 0 0 7231024 52196 506400 0 0 0 0 7859 16233 5 0 94 0 0 0 0 7231024 52196 506400 0 0 0 0 7870 16446 2 0 98 0 0 0 0 7230900 52196 506400 0 0 0 0 7308 15661 5 0 95 0 0 0 0 7231100 52196 506400 0 0 0 0 7960 16543 6 0 94 0 0 0 0 7231100 52196 506400 0 0 0 0 7542 16047 5 1 94 0 3 0 0 7231100 52196 506400 0 0 0 0 7709 16621 3 0 96 0 0 0 0 7231220 52196 506400 0 0 0 0 7857 16552 4 0 96 0 0 0 0 7231220 52196 506400 0 0 0 0 7192 15491 6 0 94 0 0 0 0 7231220 52196 506400 0 0 0 0 7423 15792 5 1 94 0 1 0 0 7231260 52196 506404 0 0 0 0 7686 16296 2 0 98 0 0 0 0 7231260 52196 506404 0 0 0 0 6976 15183 5 0 95 0 0 0 0 7231260 52196 506404 0 0 0 0 7303 15600 4 0 95 0 0 0 0 7231320 52196 506404 0 0 0 0 7967 16241 1 0 98 0 0 0 0 7231444 52196 506404 0 0 0 0 6948 15113 6 0 94 0 0 0 0 7231444 52196 506404 0 0 0 0 7931 16181 6 0 94 0 1 0 0 7231516 52196 506404 0 0 0 0 7715 15829 6 0 94 0 0 0 0 7231516 52196 506404 0 0 0 0 7771 16036 2 0 97 0 0 0 0 7231268 52196 506404 0 0 0 0 7782 16202 6 0 94 0 1 0 0 7231212 52196 506404 0 0 0 0 7457 15622 4 0 96 0 0 0 0 7231212 52196 506404 0 0 0 0 7573 16045 2 0 98 0 2 0 0 7231216 52196 506404 0 0 0 0 7689 16076 6 0 94 0 0 0 0 7231424 52196 506404 0 0 0 0 7429 15650 4 0 95 0 3 0 0 7231424 52196 506404 0 0 0 0 7534 16168 3 0 97 0 1 0 0 7230548 52196 506404 0 0 0 0 8559 15926 7 1 92 0 0 0 0 7230672 52196 506404 0 0 0 0 7720 15905 2 0 98 0 0 0 0 7230548 52196 506404 0 0 0 0 7677 16313 5 0 95 0 1 0 0 7230676 52196 506404 0 0 0 0 7209 15432 5 0 95 0 0 0 0 7230800 52196 506404 0 0 0 0 7522 15861 2 0 98 0 0 0 0 7230552 52196 506404 0 0 0 0 7760 16661 5 0 95 0 In the munin(monitoring system) graphs I see(before server hung): Disk(nbd0) IOs per device: read: 289m but avg by week 2.09m Disk(nbd0) throughput per device: read: 4.73k but avg by week 108.76 Disk(nbd0) utilization per device: 100% but avg by week 1.2% Eth0 traffic was low: in/out only 2Mbps Number of threads increased to 566 usually 392 Fork rate 1.08 but usually 2.82 VMStat(processes state) Increased to 17.77(from 0 as far as I could see in the graph) CPU usage iowait 880.46% when usually 6.67% It'll be great if somebody help me to understand what's up.

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• Why is my mdadm raid-1 recovery so slow?

  - by dimmer

  On a system I'm running Ubuntu 10.04. My raid-1 restore started out fast but quickly became ridiculously slow (at this rate the restore will take 150 days!): dimmer@paimon:~$ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid1 sdc1[2] sdb1[1] 1953513408 blocks [2/1] [_U] [====>................] recovery = 24.4% (477497344/1953513408) finish=217368.0min speed=113K/sec unused devices: <none> Eventhough I have set the kernel variables to reasonably quick values: dimmer@paimon:~$ cat /proc/sys/dev/raid/speed_limit_min 1000000 dimmer@paimon:~$ cat /proc/sys/dev/raid/speed_limit_max 100000000 I am using 2 2.0TB Western Digital Hard Disks, WDC WD20EARS-00M and WDC WD20EARS-00J. I believe they have been partitioned such that their sectors are aligned. dimmer@paimon:/sys$ sudo parted /dev/sdb GNU Parted 2.2 Using /dev/sdb Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) p Model: ATA WDC WD20EARS-00M (scsi) Disk /dev/sdb: 2000GB Sector size (logical/physical): 512B/512B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 2000GB 2000GB ext4 (parted) unit s (parted) p Number Start End Size File system Name Flags 1 2048s 3907028991s 3907026944s ext4 (parted) q dimmer@paimon:/sys$ sudo parted /dev/sdc GNU Parted 2.2 Using /dev/sdc Welcome to GNU Parted! Type 'help' to view a list of commands. (parted) p Model: ATA WDC WD20EARS-00J (scsi) Disk /dev/sdc: 2000GB Sector size (logical/physical): 512B/4096B Partition Table: gpt Number Start End Size File system Name Flags 1 1049kB 2000GB 2000GB ext4 I am beginning to think that I have a hardware problem, otherwise I can't imagine why the mdadm restore should be so slow. I have done a benchmark on /dev/sdc using Ubuntu's disk utility GUI app, and the results looked normal so I know that sdc has the capability to write faster than this. I also had the same problem on a similar WD drive that I RMAd because of bad sectors. I suppose it's possible they sent me a replacement with bad sectors too, although there are no SMART values showing them yet. Any ideas? Thanks. As requested, output of top sorted by cpu usage (notice there is ~0 cpu usage). iowait is also zero which seems strange: top - 11:35:13 up 2 days, 9:40, 3 users, load average: 2.87, 2.58, 2.30 Tasks: 142 total, 1 running, 141 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0%us, 0.2%sy, 0.0%ni, 99.8%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 3096304k total, 1482164k used, 1614140k free, 617672k buffers Swap: 1526132k total, 0k used, 1526132k free, 535416k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 45 root 20 0 0 0 0 S 0 0.0 2:17.02 scsi_eh_0 1 root 20 0 2808 1752 1204 S 0 0.1 0:00.46 init 2 root 20 0 0 0 0 S 0 0.0 0:00.00 kthreadd 3 root RT 0 0 0 0 S 0 0.0 0:00.02 migration/0 4 root 20 0 0 0 0 S 0 0.0 0:00.17 ksoftirqd/0 5 root RT 0 0 0 0 S 0 0.0 0:00.00 watchdog/0 6 root RT 0 0 0 0 S 0 0.0 0:00.02 migration/1 ... dmesg errors, definitely looking like hardware: [202884.000157] ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [202884.007015] ata5.00: failed command: FLUSH CACHE EXT [202884.013728] ata5.00: cmd ea/00:00:00:00:00/00:00:00:00:00/a0 tag 0 [202884.013730] res 40/00:00:ff:59:2e/00:00:35:00:00/e0 Emask 0x4 (timeout) [202884.033667] ata5.00: status: { DRDY } [202884.040329] ata5: hard resetting link [202889.400050] ata5: link is slow to respond, please be patient (ready=0) [202894.048087] ata5: COMRESET failed (errno=-16) [202894.054663] ata5: hard resetting link [202899.412049] ata5: link is slow to respond, please be patient (ready=0) [202904.060107] ata5: COMRESET failed (errno=-16) [202904.066646] ata5: hard resetting link [202905.840056] ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [202905.849178] ata5.00: configured for UDMA/133 [202905.849188] ata5: EH complete [203899.000292] ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [203899.007096] ata5.00: failed command: IDENTIFY DEVICE [203899.013841] ata5.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 in [203899.013843] res 40/00:00:ff:f9:f6/00:00:38:00:00/e0 Emask 0x4 (timeout) [203899.041232] ata5.00: status: { DRDY } [203899.048133] ata5: hard resetting link [203899.816134] ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [203899.826062] ata5.00: configured for UDMA/133 [203899.826079] ata5: EH complete [204375.000200] ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [204375.007421] ata5.00: failed command: IDENTIFY DEVICE [204375.014799] ata5.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 in [204375.014800] res 40/00:00:ff:0c:0f/00:00:39:00:00/e0 Emask 0x4 (timeout) [204375.044374] ata5.00: status: { DRDY } [204375.051842] ata5: hard resetting link [204380.408049] ata5: link is slow to respond, please be patient (ready=0) [204384.440076] ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [204384.449938] ata5.00: configured for UDMA/133 [204384.449955] ata5: EH complete [204395.988135] ata5.00: exception Emask 0x0 SAct 0x0 SErr 0x0 action 0x6 frozen [204395.988140] ata5.00: failed command: IDENTIFY DEVICE [204395.988147] ata5.00: cmd ec/00:01:00:00:00/00:00:00:00:00/00 tag 0 pio 512 in [204395.988149] res 40/00:00:ff:0c:0f/00:00:39:00:00/e0 Emask 0x4 (timeout) [204395.988151] ata5.00: status: { DRDY } [204395.988156] ata5: hard resetting link [204399.320075] ata5: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [204399.330487] ata5.00: configured for UDMA/133 [204399.330503] ata5: EH complete

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• CSC folder data access AND roaming profiles issues (Vista with Server 2003, then 2008)

  - by Alex Jones

  I'm a junior sysadmin for an IT contractor that helps small, local government agencies, like little towns and the like. One of our clients, a public library with ~ 50 staff users, was recently migrated from Server 2003 Standard to Server 2008 R2 Standard in a very short timeframe; our senior employee, the only network engineer, had suddenly put in his two weeks notice, so management pushed him to do this project before quitting. A bit hasty on management's part? Perhaps. Could we do anything about that? Nope. Do I have to fix this all by myself? Pretty much. The network is set up like this: a) 50ish staff workstations, all running Vista Business SP2. All staff use MS Outlook, which uses RPC-over-HTTPS ("Outlook Anywhere") for cached Exchange access to an offsite location. b) One new (virtualized) Server 2008 R2 Standard instance, running atop a Server 2008 R2 host via Hyper-V. The VM is the domain's DC, and also the site's one and only file server. Let's call that VM "NEWBOX". c) One old physical Server 2003 Standard server, running the same roles. Let's call it "OLDBOX". It's still on the network and accessible, but it's been demoted, and its shares have been disabled. No data has been deleted. c) Gigabit Ethernet everywhere. The organization's only has one domain, and it did not change during the migration. d) Most users were set up for a combo of redirected folders + offline files, but some older employees who had been with the organization a long time are still on roaming profiles. To sum up: the servers in question handle user accounts and files, nothing else (eg, no TS, no mail, no IIS, etc.) I have two major problems I'm hoping you can help me with: 1) Even though all domain users have had their redirected folders moved to the new server, and loggin in to their workstations and testing confirms that the Documents/Music/Whatever folders point to the new paths, it appears some users (not laptops or anything either!) had been working offline from OLDBOX for a long time, and nobody realized it. Here's the ugly implication: a bunch of their data now lives only in their CSC folders, because they can't access the share on OLDBOX and sync with it finally. How do I get this data out of those CSC folders, and onto NEWBOX? 2) What's the best way to migrate roaming profile users to non-roaming ones, without losing vital data like documents, any lingering PSTs, etc? Things I've thought about trying: For problem 1: a) Reenable the documents share on OLDBOX, force an Offline Files sync for ALL domain users, then copy OLDBOX's share's data to the equivalent share on NEWBOX. Reinitialize the Offline Files cache for every user. With this: How do I safely force a domain-wide Offline Files sync? Could I lose data by reenabling the share on OLDBOX and forcing the sync? Afterwards, how can I reinitialize the Offline Files cache for every user, without doing it manually, workstation by workstation? b) Determine which users have unsynced changes to OLDBOX (again, how?), search each user's CSC folder domain-wide via workstation admin shares, and grab the unsynched data. Reinitialize the Offline Files cache for every user. With this: How can I detect which users have unsynched changes with a script? How can I search each user's CSC folder, when the ownership and permissions set for CSC folders are so restrictive? Again, afterwards, how can I reinitialize the Offline Files cache for every user, without doing it manually, workstation by workstation? c) Manually visit each workstation, copy the contents of the CSC folder, and manually copy that data onto NEWBOX. Reinitialize the Offline Files cache for every user. With this: Again, how do I 'break into' the CSC folder and get to its data? As an experiment, I took one workstation's HD offsite, imaged it for safety, and then tried the following with one of our shop PCs, after attaching the drive: grant myself full control of the folder (failed), grant myself ownership of the folder (failed), run chkdsk on the whole drive to make sure nothing's messed up (all OK), try to take full control of the entire drive (failed), try to take ownership of the entire drive (failed) MS KB articles and Googling around suggests there's a utility called CSCCMD that's meant for this exact scenario...but it looks like it's available for XP, not Vista, no? Again, afterwards, how can I reinitialize the Offline Files cache for every user, without doing it manually, workstation by workstation? For problem 2: a) Figure out which users are on roaming profiles, and where their profiles 'live' on the server. Create new folders for them in the redirected folders repository, migrate existing data, and disable the roaming. With this: Finding out who's roaming isn't hard. But what's the best way to disable the roaming itself? In AD Users and Computers, or on each user's workstation? Doing it centrally on the server seems more efficient; that said, all of the KB research I've done turns up articles on how to go from local to roaming, not the other way around, so I don't have good documentation on this. In closing: we have good backups of NEWBOX and OLDBOX, but not of the workstations themselves, so anything drastic on the client side would need imaging and testing for safety. Thanks for reading along this far! Hopefully you can help me dig us out of this mess.

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• OpenVPN (HideMyAss) client on Ubuntu: Route only HTTP traffic

  - by Andersmith

  I want to use HideMyAss VPN (hidemyass.com) on Ubuntu Linux to route only HTTP (ports 80 & 443) traffic to the HideMyAss VPN server, and leave all the other traffic (MySQL, SSH, etc.) alone. I'm running Ubuntu on AWS EC2 instances. The problem is that when I try and run the default HMA script, I suddenly can't SSH into the Ubuntu instance anymore and have to reboot it from the AWS console. I suspect the Ubuntu instance will also have trouble connecting to the RDS MySQL database, but haven't confirmed it. HMA uses OpenVPN like this: sudo openvpn client.cfg The client configuration file (client.cfg) looks like this: ############################################## # Sample client-side OpenVPN 2.0 config file # # for connecting to multi-client server. # # # # This configuration can be used by multiple # # clients, however each client should have # # its own cert and key files. # # # # On Windows, you might want to rename this # # file so it has a .ovpn extension # ############################################## # Specify that we are a client and that we # will be pulling certain config file directives # from the server. client auth-user-pass #management-query-passwords #management-hold # Disable management port for debugging port issues #management 127.0.0.1 13010 ping 5 ping-exit 30 # Use the same setting as you are using on # the server. # On most systems, the VPN will not function # unless you partially or fully disable # the firewall for the TUN/TAP interface. #;dev tap dev tun # Windows needs the TAP-Win32 adapter name # from the Network Connections panel # if you have more than one. On XP SP2, # you may need to disable the firewall # for the TAP adapter. ;dev-node MyTap # Are we connecting to a TCP or # UDP server? Use the same setting as # on the server. proto tcp ;proto udp # The hostname/IP and port of the server. # You can have multiple remote entries # to load balance between the servers. # All VPN Servers are added at the very end ;remote my-server-2 1194 # Choose a random host from the remote # list for load-balancing. Otherwise # try hosts in the order specified. # We order the hosts according to number of connections. # So no need to randomize the list # remote-random # Keep trying indefinitely to resolve the # host name of the OpenVPN server. Very useful # on machines which are not permanently connected # to the internet such as laptops. resolv-retry infinite # Most clients don't need to bind to # a specific local port number. nobind # Downgrade privileges after initialization (non-Windows only) ;user nobody ;group nobody # Try to preserve some state across restarts. persist-key persist-tun # If you are connecting through an # HTTP proxy to reach the actual OpenVPN # server, put the proxy server/IP and # port number here. See the man page # if your proxy server requires # authentication. ;http-proxy-retry # retry on connection failures ;http-proxy [proxy server] [proxy port #] # Wireless networks often produce a lot # of duplicate packets. Set this flag # to silence duplicate packet warnings. ;mute-replay-warnings # SSL/TLS parms. # See the server config file for more # description. It's best to use # a separate .crt/.key file pair # for each client. A single ca # file can be used for all clients. ca ./keys/ca.crt cert ./keys/hmauser.crt key ./keys/hmauser.key # Verify server certificate by checking # that the certicate has the nsCertType # field set to "server". This is an # important precaution to protect against # a potential attack discussed here: # http://openvpn.net/howto.html#mitm # # To use this feature, you will need to generate # your server certificates with the nsCertType # field set to "server". The build-key-server # script in the easy-rsa folder will do this. ;ns-cert-type server # If a tls-auth key is used on the server # then every client must also have the key. ;tls-auth ta.key 1 # Select a cryptographic cipher. # If the cipher option is used on the server # then you must also specify it here. ;cipher x # Enable compression on the VPN link. # Don't enable this unless it is also # enabled in the server config file. #comp-lzo # Set log file verbosity. verb 3 # Silence repeating messages ;mute 20 # Detect proxy auto matically #auto-proxy # Need this for Vista connection issue route-metric 1 # Get rid of the cached password warning #auth-nocache #show-net-up #dhcp-renew #dhcp-release #route-delay 0 120 # added to prevent MITM attack ns-cert-type server # # Remote servers added dynamically by the master server # DO NOT CHANGE below this line # remote-random remote 173.242.116.200 443 # 0 remote 38.121.77.74 443 # 0 # etc... remote 67.23.177.5 443 # 0 remote 46.19.136.130 443 # 0 remote 173.254.207.2 443 # 0 # END

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• e2fsck extremly slow, although enough memory exists

  - by kaefert

  I've got this external USB-Disk: kaefert@blechmobil:~$ lsusb -s 2:3 Bus 002 Device 003: ID 0bc2:3320 Seagate RSS LLC As can be seen in this dmesg output, there are some problems that prevents that disk from beeing mounted: kaefert@blechmobil:~$ dmesg | grep sdb [ 114.474342] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.475089] sd 5:0:0:0: [sdb] Write Protect is off [ 114.475092] sd 5:0:0:0: [sdb] Mode Sense: 43 00 00 00 [ 114.475959] sd 5:0:0:0: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 114.477093] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.501649] sdb: sdb1 [ 114.502717] sd 5:0:0:0: [sdb] 732566645 4096-byte logical blocks: (3.00 TB/2.72 TiB) [ 114.504354] sd 5:0:0:0: [sdb] Attached SCSI disk [ 116.804408] EXT4-fs (sdb1): ext4_check_descriptors: Checksum for group 3976 failed (47397!=61519) [ 116.804413] EXT4-fs (sdb1): group descriptors corrupted! So I went and fired up my favorite partition manager - gparted, and told it to verify and repair the partition sdb1. This made gparted call e2fsck (version 1.42.4 (12-Jun-2012)) e2fsck -f -y -v /dev/sdb1 Although gparted called e2fsck with the "-v" option, sadly it doesn't show me the output of my e2fsck process (bugreport https://bugzilla.gnome.org/show_bug.cgi?id=467925 ) I started this whole thing on Sunday (2012-11-04_2200) evening, so about 48 hours ago, this is what htop says about it now (2012-11-06-1900): PID USER PRI NI VIRT RES SHR S CPU% MEM% TIME+ Command 3704 root 39 19 1560M 1166M 768 R 98.0 19.5 42h56:43 e2fsck -f -y -v /dev/sdb1 Now I found a few posts on the internet that discuss e2fsck running slow, for example: http://gparted-forum.surf4.info/viewtopic.php?id=13613 where they write that its a good idea to see if the disk is just that slow because maybe its damaged, and I think these outputs tell me that this is not the case in my case: kaefert@blechmobil:~$ sudo hdparm -tT /dev/sdb /dev/sdb: Timing cached reads: 3562 MB in 2.00 seconds = 1783.29 MB/sec Timing buffered disk reads: 82 MB in 3.01 seconds = 27.26 MB/sec kaefert@blechmobil:~$ sudo hdparm /dev/sdb /dev/sdb: multcount = 0 (off) readonly = 0 (off) readahead = 256 (on) geometry = 364801/255/63, sectors = 5860533160, start = 0 However, although I can read quickly from that disk, this disk speed doesn't seem to be used by e2fsck, considering tools like gkrellm or iotop or this: kaefert@blechmobil:~$ iostat -x Linux 3.2.0-2-amd64 (blechmobil) 2012-11-06 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 14,24 47,81 14,63 0,95 0,00 22,37 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util sda 0,59 8,29 2,42 5,14 43,17 160,17 53,75 0,30 39,80 8,72 54,42 3,95 2,99 sdb 137,54 5,48 9,23 0,20 587,07 22,73 129,35 0,07 7,70 7,51 16,18 2,17 2,04 Now I researched a little bit on how to find out what e2fsck is doing with all that processor time, and I found the tool strace, which gives me this: kaefert@blechmobil:~$ sudo strace -p3704 lseek(4, 41026998272, SEEK_SET) = 41026998272 write(4, "\212\354K[_\361\3nl\212\245\352\255jR\303\354\312Yv\334p\253r\217\265\3567\325\257\3766"..., 4096) = 4096 lseek(4, 48404766720, SEEK_SET) = 48404766720 read(4, "\7t\260\366\346\337\304\210\33\267j\35\377'\31f\372\252\ffU\317.y\211\360\36\240c\30`\34"..., 4096) = 4096 lseek(4, 41027002368, SEEK_SET) = 41027002368 write(4, "\232]7Ws\321\352\t\1@[+5\263\334\276{\343zZx\352\21\316`1\271[\202\350R`"..., 4096) = 4096 lseek(4, 48404770816, SEEK_SET) = 48404770816 read(4, "\17\362r\230\327\25\346//\210H\v\311\3237\323K\304\306\361a\223\311\324\272?\213\tq \370\24"..., 4096) = 4096 lseek(4, 41027006464, SEEK_SET) = 41027006464 write(4, "\367yy>x\216?=\324Z\305\351\376&\25\244\210\271\22\306}\276\237\370(\214\205G\262\360\257#"..., 4096) = 4096 lseek(4, 48404774912, SEEK_SET) = 48404774912 read(4, "\365\25\0\21|T\0\21}3t_\272\373\222k\r\177\303\1\201\261\221$\261B\232\3142\21U\316"..., 4096) = 4096 ^CProcess 3704 detached around 16 of these lines every second, so 4 read and 4 write operations every second, which I don't consider to be a lot.. And finally, my question: Will this process ever finish? If those numbers from fseek (48404774912) represent bytes, that would be something like 45 gigabytes, with this beeing a 3 terrabyte disk, which would give me 134 days to go, if the speed stays constant, and he scans the disk like this completly and only once. Do you have some advice for me? I have most of the data on that disk elsewhere, but I've put a lot of hours into sorting and merging it to this disk, so I would prefer to getting this disk up and running again, without formatting it anew. I don't think that the hardware is damaged since the disk is only a few months and since I can't see any I/O errors in the dmesg output. UPDATE: I just looked at the strace output again (2012-11-06_2300), now it looks like this: lseek(4, 1419860611072, SEEK_SET) = 1419860611072 read(4, "3#\f\2447\335\0\22A\355\374\276j\204'\207|\217V|\23\245[\7VP\251\242\276\207\317:"..., 4096) = 4096 lseek(4, 43018145792, SEEK_SET) = 43018145792 write(4, "]\206\231\342Y\204-2I\362\242\344\6R\205\361\324\177\265\317C\334V\324\260\334\275t=\10F."..., 4096) = 4096 lseek(4, 1419860615168, SEEK_SET) = 1419860615168 read(4, "\262\305\314Y\367\37x\326\245\226\226\320N\333$s\34\204\311\222\7\315\236\336\300TK\337\264\236\211n"..., 4096) = 4096 lseek(4, 43018149888, SEEK_SET) = 43018149888 write(4, "\271\224m\311\224\25!I\376\16;\377\0\223H\25Yd\201Y\342\r\203\271\24eG<\202{\373V"..., 4096) = 4096 lseek(4, 1419860619264, SEEK_SET) = 1419860619264 read(4, ";d\360\177\n\346\253\210\222|\250\352T\335M\33\260\320\261\7g\222P\344H?t\240\20\2548\310"..., 4096) = 4096 lseek(4, 43018153984, SEEK_SET) = 43018153984 write(4, "\360\252j\317\310\251G\227\335{\214`\341\267\31Y\202\360\v\374\307oq\3063\217Z\223\313\36D\211"..., 4096) = 4096 So this number of the lseeks before the reads, like 1419860619264 are already a lot bigger, standing for 1.29 terabytes if the numbers are bytes, so it doesn't seem to be a linear progress on a big scale, maybe there are only some areas that need work, that have big gaps in between them. (times are in CET)

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• Linux/Apache performance very slow even on local network

  - by klausch

  I have an Ubuntu server machine running Apache and MYSQL. System and version info is as follows: Linux kernel 3.0.0.-12 Apache/2.2.20 MySQL Ver 14.14.Distrib 5.1.58 I am running a few websites on this server, some HTML only, some PHP/MySQL. THe [problem is that response time is very slow, both on static as well as the dynamic sites. Sometimes it takes more than 10 seconds before a response is given, this makes the sites very slow and almost unusable. The problem occurs even when requesting from the local network. I have added the involved subdomains to my /etc/hosts file, and abolve all the problem is not solved by using IP numbers instead of URL's. So there is no DNS lookup issue. I have modified the log format by showing the response times and sometimes a files takes 12 seconds to be served, see the jquery~.js file in the example screenshot. I have no explanation for this extremely long response time, but is is not even the only issue here, some other files takes a long time to be served too, but do not show a long response time in the log file. So probably different tissues are involved here. I cannot find a solution until now, any suggestions??? THanx in advance, Klaas link to screenshot picture from access logfile Some extra configuration info: apache2.conf (comment is removed) LockFile ${APACHE_LOCK_DIR}/accept.lock PidFile ${APACHE_PID_FILE} Timeout 300 KeepAlive On MaxKeepAliveRequests 100 KeepAliveTimeout 5 <IfModule mpm_prefork_module> StartServers 5 MinSpareServers 5 MaxSpareServers 10 MaxClients 150 MaxRequestsPerChild 0 </IfModule> <IfModule mpm_worker_module> StartServers 2 MinSpareThreads 25 MaxSpareThreads 75 ThreadLimit 64 ThreadsPerChild 25 MaxClients 150 MaxRequestsPerChild 0 </IfModule> <IfModule mpm_event_module> StartServers 2 MinSpareThreads 25 MaxSpareThreads 75 ThreadLimit 64 ThreadsPerChild 25 MaxClients 150 MaxRequestsPerChild 0 </IfModule> User ${APACHE_RUN_USER} Group ${APACHE_RUN_GROUP} AccessFileName .htaccess <Files ~ "^\.ht"> Order allow,deny Deny from all Satisfy all </Files> DefaultType text/plain HostnameLookups Off ErrorLog ${APACHE_LOG_DIR}/error.log LogLevel warn Include mods-enabled/*.load Include mods-enabled/*.conf Include httpd.conf Include ports.conf LogFormat "%v:%p %h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\"" vhost_combined LogFormat "%h %l %u %t \"%r\" %>s %O \"%{Referer}i\" \"%{User-Agent}i\" %T/%D" combined LogFormat "%h %l %u %t \"%r\" %>s %O" common LogFormat "%{Referer}i -> %U" referer LogFormat "%{User-agent}i" agent Include conf.d/ Include sites-enabled/ And the virtual hostfile for one of the slow sites, in fact it is pretty straightforward... <VirtualHost *:80> ServerAdmin [email protected] ServerSignature EMail ServerName toenjoy.drsklaus.nl DocumentRoot /var/www/toenjoy.drsklaus.nl <Directory /> Options FollowSymLinks AllowOverride None </Directory> <Directory /var/www/toenjoy.drsklaus.nl/> Options Indexes FollowSymLinks MultiViews AllowOverride AuthConfig AuthType Basic AuthName "To Enjoy" AuthUserFile /etc/.htpasswd Require user petraaa Order allow,deny allow from all </Directory> ScriptAlias /cgi-bin/ /usr/lib/cgi-bin/ <Directory "/usr/lib/cgi-bin"> AllowOverride None Options +ExecCGI -MultiViews +SymLinksIfOwnerMatch Order allow,deny Allow from all </Directory> ErrorLog /var/log/apache2/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog /var/log/apache2/access.log combined Alias /doc/ "/usr/share/doc/" <Directory "/usr/share/doc/"> Options Indexes MultiViews FollowSymLinks AllowOverride None Order deny,allow Deny from all Allow from 127.0.0.0/255.0.0.0 ::1/128 </Directory> </VirtualHost> And the output of free -m: klaas@ubuntu-server:/etc/apache2$ free -m total used free shared buffers cached Mem: 1997 1401 595 0 144 1017 -/+ buffers/cache: 238 1758 Swap: 2035 0 2035 and I have no indication that swapping occurs on the moments the site is slow. I have runned top and it does not appear to be a CPU issue. I have the impression that the spawning of a apache thread could maybe be the bottleneck but it is just a suggestion. Maybe this gives some extra information! EDIT: The problem seemed to be gone for some time but occurs again! And not only with Apache, also connecting using SSH takes a tremendous time, sometimes it takes up to 15 seconds before the keyphrase is asked for. Also scp works very slowly. The behavious is really unpredoctable and makes the server very hard to use. Any ideas...?

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• git | error: Unable to append to .git/logs/refs/remotes/origin/master: Permission denied [SOLVED]

  - by Corbin Tarrant

  I am having a strange issue that I can't seem to resolve. Here is what happend: I had some log files in a github repository that I didn't want there. I found this script that removes files completely from git history like so: #!/bin/bash set -o errexit # Author: David Underhill # Script to permanently delete files/folders from your git repository. To use # it, cd to your repository's root and then run the script with a list of paths # you want to delete, e.g., git-delete-history path1 path2 if [ $# -eq 0 ]; then exit 0are still fi # make sure we're at the root of git repo if [ ! -d .git ]; then echo "Error: must run this script from the root of a git repository" exit 1 fi # remove all paths passed as arguments from the history of the repo files=$@ git filter-branch --index-filter "git rm -rf --cached --ignore-unmatch $files" HEAD # remove the temporary history git-filter-branch otherwise leaves behind for a long time rm -rf .git/refs/original/ && git reflog expire --all && git gc --aggressive --prune I, of course, made a backup first and then tried it. It seemed to work fine. I then did a git push -f and was greeted with the following messages: error: Unable to append to .git/logs/refs/remotes/origin/master: Permission denied error: Cannot update the ref 'refs/remotes/origin/master'. Everything seems to have pushed fine though, because the files seem to be gone from the GitHub repository, if I try and push again I get the same thing: error: Unable to append to .git/logs/refs/remotes/origin/master: Permission denied error: Cannot update the ref 'refs/remotes/origin/master'. Everything up-to-date EDIT $ sudo chgrp {user} .git/logs/refs/remotes/origin/master $ sudo chown {user} .git/logs/refs/remotes/origin/master $ git push Everything up-to-date Thanks! EDIT Uh Oh. Problem. I've been working on this project all night and just went to commit my changes: error: Unable to append to .git/logs/refs/heads/master: Permission denied fatal: cannot update HEAD ref So I: sudo chown {user} .git/logs/refs/heads/master sudo chgrp {user} .git/logs/refs/heads/master I try the commit again and I get: error: Unable to append to .git/logs/HEAD: Permission denied fatal: cannot update HEAD ref So I: sudo chown {user} .git/logs/HEAD sudo chgrp {user} .git/logs/HEAD And then I try the commit again: 16 files changed, 499 insertions(+), 284 deletions(-) create mode 100644 logs/DBerrors.xsl delete mode 100644 logs/emptyPHPerrors.php create mode 100644 logs/trimXMLerrors.php rewrite public/codeCore/Classes/php/DatabaseConnection.php (77%) create mode 100644 public/codeSite/php/init.php $ git push Counting objects: 49, done. Delta compression using up to 2 threads. Compressing objects: 100% (27/27), done. Writing objects: 100% (27/27), 7.72 KiB, done. Total 27 (delta 15), reused 0 (delta 0) To [email protected]:IAmCorbin/MooKit.git 59da24e..68b6397 master -> master Hooray. I jump on http://GitHub.com and check out the repository, and my latest commit is no where to be found. ::scratch head:: So I push again: Everything up-to-date Umm...it doesn't look like it. I've never had this issue before, could this be a problem with github? or did I mess something up with my git project? EDIT Nevermind, I did a simple: git push origin master and it pushed fine.

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• Why does my UIWebView not Allow User Interaction?

  - by thomasmcgee

  Hi, I'm new to these forums so I apologize for my noobieness. I did as thorough a search as I could, but I couldn't find anyone else with this issue, applogise if this has been covered elsewhere. I've created a very simple example of my problem. I'm sure I'm missing something but I can't for the life of me figure out what. I'm creating a UIWebView and adding it to a custom view controller that inherits from UIViewController. When the app loads in the iPad simulator, the uiwebview loads the desired page, but the UIWebView is entirely unresponsive. The webview does not pan or scroll and none of the in page links can be clicked. However, if you change the orientation of the webview suddleny everything works. Thanks in advance for your help!! AppDelegate header #import <UIKit/UIKit.h> #import "EditorViewController.h" @interface FixEditorTestAppDelegate : NSObject <UIApplicationDelegate> { UIWindow *window; EditorViewController *editorView; } @property (nonatomic, retain) IBOutlet UIWindow *window; @property (nonatomic, retain) EditorViewController *editorView; @end AppDelegate Implementation #import "FixEditorTestAppDelegate.h" #import "EditorViewController.h" @implementation FixEditorTestAppDelegate @synthesize window; @synthesize editorView; - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { NSLog(@"application is loading"); editorView = [[EditorViewController alloc] init]; [window addSubview:[editorView view]]; [window makeKeyAndVisible]; return YES; } - (void)dealloc { [window release]; [editorView release]; [super dealloc]; } @end View Controller header #import <UIKit/UIKit.h> @interface EditorViewController : UIViewController <UIWebViewDelegate> { UIWebView *webView; } @property (nonatomic, retain) UIWebView *webView; @end View Controller Implementation #import "EditorViewController.h" @implementation EditorViewController @synthesize webView; /* // The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if ((self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil])) { // Custom initialization } return self; } */ // Implement loadView to create a view hierarchy programmatically, without using a nib. - (void)loadView { NSLog(@"loadView called"); UIView *curView = [[UIView alloc] init]; webView = [[UIWebView alloc] init]; webView.frame = CGRectMake(20, 40, 728, 964); webView.delegate = self; webView.backgroundColor = [UIColor redColor]; [curView addSubview: webView]; self.view = curView; [curView release]; } //Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; NSLog(@"viewDidLoad called"); NSURL *url = [[NSURL alloc] initWithString:@"http://www.nytimes.com"]; NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url]; [webView loadRequest:request]; [url autorelease]; [request release]; } - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Overriden to allow any orientation. return YES; } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { webView.delegate = nil; [webView release]; [super viewDidUnload]; // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (void)dealloc { [super dealloc]; } @end

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• .NET: Serializing object to a file from a 3rd party assembly

  - by MacGyver

  Below is a link that describes how to serialize an object. But it requires you implement from ISerializable for the object you are serializing. What I'd like to do is serialize an object that I did not define--an object based on a class in a 3rd party assembly (from a project reference) that is not implementing ISerializable. Is that possible? How can this be done? http://www.switchonthecode.com/tutorials/csharp-tutorial-serialize-objects-to-a-file Property (IWebDriver = interface type): private IWebDriver driver; Object Instance (FireFoxDriver is a class type): driver = new FirefoxDriver(firefoxProfile); ================ 3/21/2012 update after answer posted Why would this throw an error? It doesn't like this line: serializedObject.DriverInstance = (FirefoxDriver)driver; ... Error: Cannot implicitly convert type 'OpenQA.Selenium.IWebDriver' to 'OpenQA.Selenium.Firefox.FirefoxDriver'. An explicit conversion exists (are you missing a cast?) Here is the code: FirefoxDriverSerialized serializedObject = new FirefoxDriverSerialized(); Serializer serializer = new Serializer(); serializedObject = serializer.DeSerializeObject(@"C:\firefoxDriver.qa"); driver = serializedObject.DriverInstance; if (driver == null) { driver = new FirefoxDriver(firefoxProfile); serializedObject.DriverInstance = (FirefoxDriverSerialized)driver; serializer.SerializeObject(@"C:\firefoxDriver.qa", serializedObject); } Here are the two Serializer classes I built: public class Serializer { public Serializer() { } public void SerializeObject(string filename, FirefoxDriverSerialized objectToSerialize) { Stream stream = File.Open(filename, FileMode.Create); BinaryFormatter bFormatter = new BinaryFormatter(); bFormatter.Serialize(stream, objectToSerialize); stream.Close(); } public FirefoxDriverSerialized DeSerializeObject(string filename) { FirefoxDriverSerialized objectToSerialize; Stream stream = File.Open(filename, FileMode.Open); BinaryFormatter bFormatter = new BinaryFormatter(); objectToSerialize = (FirefoxDriverSerialized)bFormatter.Deserialize(stream); stream.Close(); return objectToSerialize; } } [Serializable()] public class FirefoxDriverSerialized : FirefoxDriver, ISerializable { private FirefoxDriver driverInstance; public FirefoxDriver DriverInstance { get { return this.driverInstance; } set { this.driverInstance = value; } } public FirefoxDriverSerialized() { } public FirefoxDriverSerialized(SerializationInfo info, StreamingContext ctxt) { this.driverInstance = (FirefoxDriver)info.GetValue("DriverInstance", typeof(FirefoxDriver)); } public void GetObjectData(SerializationInfo info, StreamingContext ctxt) { info.AddValue("DriverInstance", this.driverInstance); } } ================= 3/23/2012 update #2 - fixed serialization/de-serialization, but having another issue (might be relevant for new question) This fixed the calling code. Because we're deleting the *.qa file when we call the WebDriver.Quit() because that's when we chose to close the browser. This will kill off our cached driver as well. So if we start with a new browser window, we'll hit the catch block and create a new instance and save it to our *.qa file (in the serialized form). FirefoxDriverSerialized serializedObject = new FirefoxDriverSerialized(); Serializer serializer = new Serializer(); try { serializedObject = serializer.DeSerializeObject(@"C:\firefoxDriver.qa"); driver = serializedObject.DriverInstance; } catch { driver = new FirefoxDriver(firefoxProfile); serializedObject = new FirefoxDriverSerialized(); serializedObject.DriverInstance = (FirefoxDriver)driver; serializer.SerializeObject(@"C:\firefoxDriver.qa", serializedObject); } However, still getting this exception: Acu.QA.Main.Test_0055_GiftCertificate_UserCheckout: SetUp : System.Runtime.Serialization.SerializationException : Type 'OpenQA.Selenium.Firefox.FirefoxDriver' in Assembly 'WebDriver, Version=2.16.0.0, Culture=neutral, PublicKeyToken=1c2bd1631853048f' is not marked as serializable. TearDown : System.NullReferenceException : Object reference not set to an instance of an object. The 3rd line in this code block is throwing the exception: public void SerializeObject(string filename, FirefoxDriverSerialized objectToSerialize) { Stream stream = File.Open(filename, FileMode.Create); BinaryFormatter bFormatter = new BinaryFormatter(); bFormatter.Serialize(stream, objectToSerialize); // <=== this line stream.Close(); }

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• Passing integer lists in a sql query, best practices

  - by Artiom Chilaru

  I'm currently looking at ways to pass lists of integers in a SQL query, and try to decide which of them is best in which situation, what are the benefots of each, and what are the pitfalls, what should be avoided :) Right now I know of 3 ways that we currently use in our application. 1) Table valued parameter: Create a new Table Valued Parameter in sql server: CREATE TYPE [dbo].[TVP_INT] AS TABLE( [ID] [int] NOT NULL ) Then run the query against it: using (var conn = new SqlConnection(DataContext.GetDefaultConnectionString)) { var comm = conn.CreateCommand(); comm.CommandType = CommandType.Text; comm.CommandText = @" UPDATE DA SET [tsLastImportAttempt] = CURRENT_TIMESTAMP FROM [Account] DA JOIN @values IDs ON DA.ID = IDs.ID"; comm.Parameters.Add(new SqlParameter("values", downloadResults.Select(d => d.ID).ToDataTable()) { TypeName = "TVP_INT" }); conn.Open(); comm.ExecuteScalar(); } The major disadvantages of this method is the fact that Linq doesn't support table valued params (if you create an SP with a TVP param, linq won't be able to run it) :( 2) Convert the list to Binary and use it in Linq! This is a bit better.. Create an SP, and you can run it within linq :) To do this, the SP will have an IMAGE parameter, and we'll be using a user defined function (udf) to convert this to a table.. We currently have implementations of this function written in C++ and in assembly, both have pretty much the same performance :) Basically, each integer is represented by 4 bytes, and passed to the SP. In .NET we have an extension method that convers an IEnumerable to a byte array The extension method: public static Byte[] ToBinary(this IEnumerable intList) { return ToBinaryEnum(intList).ToArray(); } private static IEnumerable<Byte> ToBinaryEnum(IEnumerable<Int32> intList) { IEnumerator<Int32> marker = intList.GetEnumerator(); while (marker.MoveNext()) { Byte[] result = BitConverter.GetBytes(marker.Current); Array.Reverse(result); foreach (byte b in result) yield return b; } } The SP: CREATE PROCEDURE [Accounts-UpdateImportAttempts] @values IMAGE AS BEGIN UPDATE DA SET [tsLastImportAttempt] = CURRENT_TIMESTAMP FROM [Account] DA JOIN dbo.udfIntegerArray(@values, 4) IDs ON DA.ID = IDs.Value4 END And we can use it by running the SP directly, or in any linq query we need using (var db = new DataContext()) { db.Accounts_UpdateImportAttempts(downloadResults.Select(d => d.ID).ToBinary()); // or var accounts = db.Accounts .Where(a => db.udfIntegerArray(downloadResults.Select(d => d.ID).ToBinary(), 4) .Select(i => i.Value4) .Contains(a.ID)); } This method has the benefit of using compiled queries in linq (which will have the same sql definition, and query plan, so will also be cached), and can be used in SPs as well. Both these methods are theoretically unlimited, so you can pass millions of ints at a time :) 3) The simple linq .Contains() It's a more simple approach, and is perfect in simple scenarios. But is of course limited by this. using (var db = new DataContext()) { var accounts = db.Accounts .Where(a => downloadResults.Select(d => d.ID).Contains(a.ID)); } The biggest drawback of this method is that each integer in the downloadResults variable will be passed as a separate int.. In this case, the query is limited by sql (max allowed parameters in a sql query, which is a couple of thousand, if I remember right). So I'd like to ask.. What do you think is the best of these, and what other methods and approaches have I missed?

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• How i set the background color in UIView using CGContext?

  - by Rajendra Bhole

  Hi, I have developed the application in which i want to set the background color of UIView which is already set on UIViewController.The code is below, @implementation frmGraphView /* // The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { // Custom initialization } return self; } */ - (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame:frame]) { // Initialization code } return self; } /* // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; } */ /* // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } */ - (void)drawRect:(CGRect)rect { CGContextRef ctx = UIGraphicsGetCurrentContext(); CGContextClearRect(ctx, rect); //CGContextSetCMYKFillColor(ctx, 35.0, 56.0, 34.0, 30.0, 1.0); //CGContextSetRGBFillColor(ctx, 92.0f, 95.0f, 97.0f, 1.0f); //CGContextFillRect(ctx, CGRectMake(0, 0, 300, 280)); CGContextSetRGBStrokeColor(ctx, 2.0, 2.0, 2.0, 1.0); CGContextSetLineWidth(ctx, 2.0); float fltX1,fltX2,fltY1,fltY2=0; NSArray *hoursInDays = [[NSArray alloc] initWithObjects:@"0",@"1" ,@"2",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12", nil]; fltX1 = 30; fltY1 = 5; fltX2 = fltX1; fltY2 = 270; //Dividing the Y-axis CGContextMoveToPoint(ctx, fltX1, fltY1); CGContextAddLineToPoint(ctx, fltX2, fltY2); //float y = 275; for(int intIndex = 0 ; intIndex < [hoursInDays count] ; fltY2-=20, intIndex++) { CGContextSetRGBStrokeColor(ctx, 2.0, 2.0, 2.0, 1.0); CGContextMoveToPoint(ctx, fltX1-3 , fltY2); CGContextAddLineToPoint(ctx, fltX1+3, fltY2); CGContextSelectFont(ctx, "Helvetica", 14.0, kCGEncodingMacRoman); CGContextSetTextDrawingMode(ctx, kCGTextFill); CGContextSetRGBFillColor(ctx, 0, 255, 255, 1); CGAffineTransform xform = CGAffineTransformMake( 1.0, 0.0, 0.0, -1.0, 0.0, 0.0); CGContextSetTextMatrix(ctx, xform); const char *arrayDataForYAxis = [[hoursInDays objectAtIndex:intIndex] UTF8String]; CGContextShowTextAtPoint(ctx, fltX1-18, fltY2-18 , arrayDataForYAxis, strlen(arrayDataForYAxis)); CGContextStrokePath(ctx); } CGContextSetRGBStrokeColor(ctx, 2.0, 2.0, 2.0, 1.0); CGContextSetLineWidth(ctx, 2.0); fltX1 = 5; fltY1 = 250; fltX2 = 270; fltY2 = fltY1; NSArray *weekDays =[[NSArray alloc] initWithObjects:@"Sun", @"Mon", @"Tus", @"Wed", @"Thu", @"Fri", @"Sat", nil]; //Dividing the X-axis CGContextMoveToPoint(ctx, fltX1, fltY1); CGContextAddLineToPoint(ctx, fltX2, fltY2); //float y = 275; for(int intIndex = 0 ; intIndex < [weekDays count] ; fltX1+=33, intIndex++) { CGContextSetRGBStrokeColor(ctx, 2.0, 2.0, 2.0, 1.0); CGContextMoveToPoint(ctx, fltX1+52 , fltY2-3); CGContextAddLineToPoint(ctx, fltX1+52, fltY2+3); CGContextSelectFont(ctx, "Arial", 15.0, kCGEncodingMacRoman); CGContextSetTextDrawingMode(ctx, kCGTextFill); CGContextSetRGBFillColor(ctx, 0, 255, 255, 1); CGAffineTransform xform = CGAffineTransformMake( 1.0, 0.0, 0.0, -1.0, 0.0, 0.0); CGContextSetTextMatrix(ctx, xform); const char *arrayDataForXAxis = [[weekDays objectAtIndex:intIndex] UTF8String]; CGContextShowTextAtPoint(ctx, fltX1+37, fltY2+18 , arrayDataForXAxis, strlen(arrayDataForXAxis)); CGContextStrokePath(ctx); } } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (void)dealloc { [super dealloc]; } @end

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• Need help with BOOST_FOREACH/compiler bug

  - by Jacek Lawrynowicz

  I know that boost or compiler should be last to blame, but I can't see another explanation here. I'm using msvc 2008 SP1 and boost 1.43. In the following code snippet execution never leaves third BOOST_FOREACH loop typedef Graph<unsigned, unsigned>::VertexIterator Iter; Graph<unsigned, unsigned> g; g.createVertex(0x66); // works fine Iter it = g.getVertices().first, end = g.getVertices().second; for(; it != end; ++it) ; // fine std::pair<Iter, Iter> p = g.getVertices(); BOOST_FOREACH(unsigned handle, p) ; // fine unsigned vertex_count = 0; BOOST_FOREACH(unsigned handle, g.getVertices()) vertex_count++; // oops, infinite loop vertex_count = 0; BOOST_FOREACH(unsigned handle, g.getVertices()) vertex_count++; vertex_count = 0; BOOST_FOREACH(unsigned handle, g.getVertices()) vertex_count++; // ... last block repeated 7 times Iterator code: class Iterator : public boost::iterator_facade<Iterator, unsigned const, boost::bidirectional_traversal_tag> { public: Iterator() : list(NULL), handle(INVALID_ELEMENT_HANDLE) {} explicit Iterator(const VectorElementsList &list, unsigned handle = INVALID_ELEMENT_HANDLE) : list(&list), handle(handle) {} friend std::ostream& operator<<(std::ostream &s, const Iterator &it) { s << "[list: " << it.list <<", handle: " << it.handle << "]"; return s; } private: friend class boost::iterator_core_access; void increment() { handle = list->getNext(handle); } void decrement() { handle = list->getPrev(handle); } unsigned const& dereference() const { return handle; } bool equal(Iterator const& other) const { return handle == other.handle && list == other.list; } const VectorElementsList<T> *list; unsigned handle; }; Some ASM fun: vertex_count = 0; BOOST_FOREACH(unsigned handle, g.getVertices()) // initialization 013E1369 mov edi,dword ptr [___defaultmatherr+8 (13E5034h)] // end iterator handle: 0xFFFFFFFF 013E136F mov ebp,dword ptr [esp+0ACh] // begin iterator handle: 0x0 013E1376 lea esi,[esp+0A8h] // begin iterator list pointer 013E137D mov ebx,esi 013E137F nop // forever loop begin 013E1380 cmp ebp,edi 013E1382 jne main+238h (13E1388h) 013E1384 cmp ebx,esi 013E1386 je main+244h (13E1394h) 013E1388 lea eax,[esp+18h] 013E138C push eax // here iterator is incremented in ram 013E138D call boost::iterator_facade<detail::VectorElementsList<Graph<unsigned int,unsigned int>::VertexWrapper>::Iterator,unsigned int const ,boost::bidirectional_traversal_tag,unsigned int const &,int>::operator++ (13E18E0h) 013E1392 jmp main+230h (13E1380h) vertex_count++; // forever loop end It's easy to see that iterator handle is cached in EBP and it never gets incremented despite of a call to iterator operator++() function. I've replaced Itarator implmentation with one deriving from std::iterator and the issue persisted, so this is not iterator_facade fault. This problem exists only on msvc 2008 SP1 x86 and amd64 release builds. Debug builds on msvc 2008 and debug/release builds on msvc 2010 and gcc 4.4 (linux) works fine. Furthermore the BOOST_FOREACH block must be repeaded exacly 10 times. If it's repeaded 9 times, it's all OK. I guess that due to BOOST_FOREACH use of template trickery (const auto_any), compiler assumes that iterator handle is constant and never reads its real value again. I would be very happy to hear that my code is wrong, correct it and move on with BOOST_FOREACH, which I'm very found of (as opposed to BOOST_FOREVER :). May be related to: http://stackoverflow.com/questions/1275852/why-does-boost-foreach-not-work-sometimes-with-c-strings

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• App crashes after a few seconds

  - by Declan Scott

  when i launch my app, on trying to do something, it will crash after a couple of seconds. I have warnings of warning: incorrect implementation of "downloadTextViewCOntroller. I also have "method definiton for -timerFinished not found and"method definiton for -timerFinished not found" this is my .m plese help me. the .h is also t the bottom // // downloadTextViewController.m // downloadText // // Created by Declan Scott on 18/03/10. // Copyright MyCompanyName 2010. All rights reserved. // #import "downloadTextViewController.h" @implementation downloadTextViewController @synthesize start; -(IBAction)tapit { start.hidden = YES; } -(void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration { if (fabsf(acceleration.x) 2.0 || fabsf(acceleration.y) 2.0 || fabsf(acceleration.z) 2.0) { UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:@"This app was developed by Declan Scott and demonstrates NSURLConnection and NSMutableData" delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil]; [alert show]; [alert release]; } } (NSString *) saveFilePath { NSArray *pathArray = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); return [[pathArray objectAtIndex:0] stringByAppendingPathComponent:@"savedddata.plist"]; } (void)applicationWillTerminate:(UIApplication *)application { NSArray *values = [[NSArray alloc] initWithObjects:textView.text,nil]; [values writeToFile:[self saveFilePath] atomically:YES]; [values release]; } (void)viewDidLoad { UIAccelerometer *accelerometer = [UIAccelerometer sharedAccelerometer]; accelerometer.delegate = self; accelerometer.updateInterval = 1.0f/60.0f; NSString *myPath = [self saveFilePath]; NSLog(myPath); BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:myPath]; if (fileExists) { NSArray *values = [[NSArray alloc] initWithContentsOfFile:myPath]; textView.text = [values objectAtIndex:0]; [values release]; } // notification UIApplication *myApp = [UIApplication sharedApplication]; // add yourself to the dispatch table [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillTerminate:) name:UIApplicationWillTerminateNotification object:myApp]; [super viewDidLoad]; } // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (IBAction)fetchData { loadingAlert = [[UIAlertView alloc] initWithTitle:@"Loading…\n\n\n\n" message:nil delegate:self cancelButtonTitle:@"Cancel Timer" otherButtonTitles:nil]; [loadingAlert show]; UIActivityIndicatorView *activityView = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite]; activityView.frame = CGRectMake(139.0f-18.0f, 60.0f, 37.0f, 37.0f); [loadingAlert addSubview:activityView]; [activityView startAnimating]; timer = [NSTimer scheduledTimerWithTimeInterval:10.0f target:self selector:@selector(timerFinished) userInfo:nil repeats:NO]; NSURLRequest *downloadRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://simpsonatyapps.com/exampletext.txt"] cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:1.0]; NSURLConnection *downloadConnection = [[NSURLConnection alloc] initWithRequest:downloadRequest delegate:self]; if (downloadConnection) downloadedData = [[NSMutableData data] retain]; else { // Error } } (void)connection:(NSURLConnection *)downloadConnection didReceiveData:(NSData *)data { [downloadedData appendData:data]; NSString *file = [[NSString alloc] initWithData:downloadedData encoding:NSUTF8StringEncoding]; textView.text = file; // get rid of alert [loadingAlert dismissWithClickedButtonIndex:-1 animated:YES]; [loadingAlert release]; /// add badge [[UIApplication sharedApplication] setApplicationIconBadgeNumber:1]; } (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } (void)dealloc { [super dealloc]; } (NSCachedURLResponse *)connection:(NSURLConnection *)connection willCacheResponse:(NSCachedURLResponse *)cachedResponse { return nil; } @end // // downloadTextViewController.h // downloadText // // Created by Declan Scott on 18/03/10. // Copyright MyCompanyName 2010. All rights reserved. // import @interface downloadTextViewController : UIViewController { IBOutlet UITextView *textView; NSMutableData *downloadedData; UIAlertView *loadingAlert; NSTimer *timer; IBOutlet UIButton *start; } - (IBAction)fetchData; - (IBAction)tapIt; - (void)timerFinished; @property (nonatomic, retain) UIButton *start; @end

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• How to have two UIPickerViews together in one ViewController?

  - by 0SX

  I'm trying to put 2 UIPickerViews together in one ViewController. Each UIPickerView has different data arrays. I'm using interface builder to link the pickers up. I know I'll have to use separate delegates and dataSources but I can't seem to hook everything up with interface builder correctly. Here's all my code: pickerTesting.h #import <UIKit/UIKit.h> #import "picker2DataSource.h" @interface pickerTestingViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource>{ IBOutlet UIPickerView *picker; IBOutlet UIPickerView *picker2; NSMutableArray *pickerViewArray; } @property (nonatomic, retain) IBOutlet UIPickerView *picker; @property (nonatomic, retain) IBOutlet UIPickerView *picker2; @property (nonatomic, retain) NSMutableArray *pickerViewArray; @end pickerTesting.m #import "pickerTestingViewController.h" @implementation pickerTestingViewController @synthesize picker, picker2, pickerViewArray; - (void)viewDidLoad { [super viewDidLoad]; pickerViewArray = [[NSMutableArray alloc] init]; [pickerViewArray addObject:@" 100 "]; [pickerViewArray addObject:@" 200 "]; [pickerViewArray addObject:@" 400 "]; [pickerViewArray addObject:@" 600 "]; [pickerViewArray addObject:@" 1000 "]; [picker selectRow:1 inComponent:0 animated:NO]; picker2.delegate = self; picker2.dataSource = self; } - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)picker; { return 1; } - (void)pickerView:(UIPickerView *)picker didSelectRow:(NSInteger)row inComponent:(NSInteger)component { } - (NSInteger)pickerView:(UIPickerView *)picker numberOfRowsInComponent:(NSInteger)component; { return [pickerViewArray count]; } - (NSString *)pickerView:(UIPickerView *)picker titleForRow:(NSInteger)row forComponent:(NSInteger)component; { return [pickerViewArray objectAtIndex:row]; } - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (void)dealloc { [super dealloc]; } @end And I have a separate class for the other datasource. picker2DataSource.h @interface picker2DataSource : NSObject <UIPickerViewDataSource, UIPickerViewDelegate> { NSMutableArray *customPickerArray; } @property (nonatomic, retain) NSMutableArray *customPickerArray; @end picker2DataSource.m #import "picker2DataSource.h" @implementation picker2DataSource @synthesize customPickerArray; - (id)init { // use predetermined frame size self = [super init]; if (self) { customPickerArray = [[NSMutableArray alloc] init]; [customPickerArray addObject:@" a "]; [customPickerArray addObject:@" b "]; [customPickerArray addObject:@" c "]; [customPickerArray addObject:@" d "]; [customPickerArray addObject:@" e "]; } return self; } - (void)dealloc { [customPickerArray release]; [super dealloc]; } - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)picker2; { return 1; } - (void)pickerView:(UIPickerView *)picker2 didSelectRow:(NSInteger)row inComponent:(NSInteger)component { } - (NSInteger)pickerView:(UIPickerView *)picker2 numberOfRowsInComponent:(NSInteger)component; { return [customPickerArray count]; } - (NSString *)pickerView:(UIPickerView *)picker2 titleForRow:(NSInteger)row forComponent:(NSInteger)component; { return [customPickerArray objectAtIndex:row]; } @end Any help or code examples would be great. Thanks.

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• Calculate a set of concatenated sets of n sets

  - by Andras Zoltan

  Okay - I'm not even sure that the term is right - and I'm sure there is bound to be a term for this - but I'll do my best to explain. This is not quite a cross product here, and the order of the results are absolutely crucial. Given: IEnumerable<IEnumerable<string>> sets = new[] { /* a */ new[] { "a", "b", "c" }, /* b */ new[] { "1", "2", "3" }, /* c */ new[] { "x", "y", "z" } }; Where each inner enumerable represents an instruction to produce a set of concatenations as follows (the order here is important): set a* = new string[] { "abc", "ab", "a" }; set b* = new string[] { "123", "12", "1" }; set c* = new string[] { "xyz", "xy", "x" }; I want to produce set ordered concatenations as follows: set final = new string { a*[0] + b*[0] + c*[0], /* abc123xyz */ a*[0] + b*[0] + c*[1], /* abc123xy */ a*[0] + b*[0] + c*[2], /* abc123x */ a*[0] + b*[0], /* abc123 */ a*[0] + b*[1] + c*[0], /* abc12xyz */ a*[0] + b*[1] + c*[1], /* abc12xy */ a*[0] + b*[1] + c*[2], /* abc12x */ a*[0] + b*[1], /* abc12 */ a*[0] + b*[2] + c*[0], /* abc1xyz */ a*[0] + b*[2] + c*[1], /* abc1xy */ a*[0] + b*[2] + c*[2], /* abc1x */ a*[0] + b*[2], /* abc1 */ a*[0], /* abc */ a*[1] + b*[0] + c*[0], /* ab123xyz */ /* and so on for a*[1] */ /* ... */ a*[2] + b*[0] + c*[0], /* a123xyz */ /* and so on for a*[2] */ /* ... */ /* now lop off a[*] and start with b + c */ b*[0] + c*[0], /* 123xyz */ /* rest of the combinations of b + c with b on its own as well */ /* then finally */ c[0], c[1], c[2]}; So clearly, there are going to be a lot of combinations! I can see similarities with Numeric bases (since the order is important as well), and I'm sure there are permutations/combinations lurking in here too. The question is - how to write an algorithm like this that'll cope with any number of sets of strings? Linq, non-Linq; I'm not fussed. Why am I doing this? Indeed, why!? In Asp.Net MVC - I want to have partial views that can be redefined for a given combination of back-end/front-end culture and language. The most basic of these would be, for a given base view View, we could have View-en-GB, View-en, View-GB, and View, in that order of precedence (recognising of course that the language/culture codes could be the same, so some combinations might be the same - a Distinct() will solve that). But I also have other views that, in themselves, have other possible combinations before culture is even taken into account (too long to go into - but the fact is, this algo will enable a whole bunch of really cool that I want to offer my developers!). I want to produce a search list of all the acceptable view names, iterate through the whole lot until the most specific match is found (governed by the order that this algo will produce these concatenations in) then serve up the resolved Partial View. The result of the search can later be cached to avoid the expense of running the algorithm all the time. I already have a really basic version of this working that just has one enumerable of strings. But this is a whole different kettle of seafood! Any help greatly appreciated.

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• multiple-inheritance substitution

  - by Luigi

  I want to write a module (framework specific), that would wrap and extend Facebook PHP-sdk (https://github.com/facebook/php-sdk/). My problem is - how to organize classes, in a nice way. So getting into details - Facebook PHP-sdk consists of two classes: BaseFacebook - abstract class with all the stuff sdk does Facebook - extends BaseFacebook, and implements parent abstract persistance-related methods with default session usage Now I have some functionality to add: Facebook class substitution, integrated with framework session class shorthand methods, that run api calls, I use mostly (through BaseFacebook::api()), authorization methods, so i don't have to rewrite this logic every time, configuration, sucked up from framework classes, insted of passed as params caching, integrated with framework cache module I know something has gone very wrong, because I have too much inheritance that doesn't look very normal.Wrapping everything in one "complex extension" class also seems too much. I think I should have few working togheter classes - but i get into problems like: if cache class doesn't really extend and override BaseFacebook::api() method - shorthand and authentication classes won't be able to use the caching. Maybe some kind of a pattern would be right in here? How would you organize these classes and their dependencies? EDIT 04.07.2012 Bits of code, related to the topic: This is how the base class of Facebook PHP-sdk: abstract class BaseFacebook { // ... some methods public function api(/* polymorphic */) { // ... method, that makes api calls } public function getUser() { // ... tries to get user id from session } // ... other methods abstract protected function setPersistentData($key, $value); abstract protected function getPersistentData($key, $default = false); // ... few more abstract methods } Normaly Facebook class extends it, and impelements those abstract methods. I replaced it with my substitude - Facebook_Session class: class Facebook_Session extends BaseFacebook { protected function setPersistentData($key, $value) { // ... method body } protected function getPersistentData($key, $default = false) { // ... method body } // ... implementation of other abstract functions from BaseFacebook } Ok, then I extend this more with shorthand methods and configuration variables: class Facebook_Custom extends Facebook_Session { public funtion __construct() { // ... call parent's constructor with parameters from framework config } public function api_batch() { // ... a wrapper for parent's api() method return $this->api('/?batch=' . json_encode($calls), 'POST'); } public function redirect_to_auth_dialog() { // method body } // ... more methods like this, for common queries / authorization } I'm not sure, if this isn't too much for a single class ( authorization / shorthand methods / configuration). Then there comes another extending layer - cache: class Facebook_Cache extends Facebook_Custom { public function api() { $cache_file_identifier = $this->getUser(); if(/* cache_file_identifier is not null and found a valid file with cached query result */) { // return the result } else { try { // call Facebook_Custom::api, cache and return the result } catch(FacebookApiException $e) { // if Access Token is expired force refreshing it parent::redirect_to_auth_dialog(); } } } // .. some other stuff related to caching } Now this pretty much works. New instance of Facebook_Cache gives me all the functionality. Shorthand methods from Facebook_Custom use caching, because Facebook_Cache overwrited api() method. But here is what is bothering me: I think it's too much inheritance. It's all very tight coupled - like look how i had to specify 'Facebook_Custom::api' instead of 'parent:api', to avoid api() method loop on Facebook_Cache class extending. Overall mess and ugliness. So again, this works but I'm just asking about patterns / ways of doing this in a cleaner and smarter way.

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• Get User SID From Logon ID (Windows XP and Up)

  - by Dave Ruske

  I have a Windows service that needs to access registry hives under HKEY_USERS when users log on, either locally or via Terminal Server. I'm using a WMI query on win32_logonsession to receive events when users log on, and one of the properties I get from that query is a LogonId. To figure out which registry hive I need to access, now, I need the users's SID, which is used as a registry key name beneath HKEY_USERS. In most cases, I can get this by doing a RelatedObjectQuery like so (in C#): RelatedObjectQuery relatedQuery = new RelatedObjectQuery( "associators of {Win32_LogonSession.LogonId='" + logonID + "'} WHERE AssocClass=Win32_LoggedOnUser Role=Dependent" ); where "logonID" is the logon session ID from the session query. Running the RelatedObjectQuery will generally give me a SID property that contains exactly what I need. There are two issues I have with this. First and most importantly, the RelatedObjectQuery will not return any results for a domain user that logs in with cached credentials, disconnected from the domain. Second, I'm not pleased with the performance of this RelatedObjectQuery --- it can take up to several seconds to execute. Here's a quick and dirty command line program I threw together to experiment with the queries. Rather than setting up to receive events, this just enumerates the users on the local machine: using System; using System.Collections.Generic; using System.Text; using System.Management; namespace EnumUsersTest { class Program { static void Main( string[] args ) { ManagementScope scope = new ManagementScope( "\\\\.\\root\\cimv2" ); string queryString = "select * from win32_logonsession"; // for all sessions //string queryString = "select * from win32_logonsession where logontype = 2"; // for local interactive sessions only ManagementObjectSearcher sessionQuery = new ManagementObjectSearcher( scope, new SelectQuery( queryString ) ); ManagementObjectCollection logonSessions = sessionQuery.Get(); foreach ( ManagementObject logonSession in logonSessions ) { string logonID = logonSession["LogonId"].ToString(); Console.WriteLine( "=== {0}, type {1} ===", logonID, logonSession["LogonType"].ToString() ); RelatedObjectQuery relatedQuery = new RelatedObjectQuery( "associators of {Win32_LogonSession.LogonId='" + logonID + "'} WHERE AssocClass=Win32_LoggedOnUser Role=Dependent" ); ManagementObjectSearcher userQuery = new ManagementObjectSearcher( scope, relatedQuery ); ManagementObjectCollection users = userQuery.Get(); foreach ( ManagementObject user in users ) { PrintProperties( user.Properties ); } } Console.WriteLine( "\nDone! Press a key to exit..." ); Console.ReadKey( true ); } private static void PrintProperty( PropertyData pd ) { string value = "null"; string valueType = "n/a"; if ( null == pd.Value ) value = "null"; if ( pd.Value != null ) { value = pd.Value.ToString(); valueType = pd.Value.GetType().ToString(); } Console.WriteLine( " \"{0}\" = ({1}) \"{2}\"", pd.Name, valueType, value ); } private static void PrintProperties( PropertyDataCollection properties ) { foreach ( PropertyData pd in properties ) { PrintProperty( pd ); } } } } So... is there way to quickly and reliably obtain the user SID given the information I retrieve from WMI, or should I be looking at using something like SENS instead?

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• Using UUIDs for cheap equals() and hashCode()

  - by Tom McIntyre

  I have an immutable class, TokenList, which consists of a list of Token objects, which are also immutable: @Immutable public final class TokenList { private final List<Token> tokens; public TokenList(List<Token> tokens) { this.tokens = Collections.unmodifiableList(new ArrayList(tokens)); } public List<Token> getTokens() { return tokens; } } I do several operations on these TokenLists that take multiple TokenLists as inputs and return a single TokenList as the output. There can be arbitrarily many TokenLists going in, and each can have arbitrarily many Tokens. These operations are expensive, and there is a good chance that the same operation (ie the same inputs) will be performed multiple times, so I would like to cache the outputs. However, performance is critical, and I am worried about the expense of performing hashCode() and equals() on these objects that may contain arbitrarily many elements (as they are immutable then hashCode could be cached, but equals will still be expensive). This led me to wondering whether I could use a UUID to provide equals() and hashCode() simply and cheaply by making the following updates to TokenList: @Immutable public final class TokenList { private final List<Token> tokens; private final UUID uuid; public TokenList(List<Token> tokens) { this.tokens = Collections.unmodifiableList(new ArrayList(tokens)); this.uuid = UUID.randomUUID(); } public List<Token> getTokens() { return tokens; } public UUID getUuid() { return uuid; } } And something like this to act as a cache key: @Immutable public final class TopicListCacheKey { private final UUID[] uuids; public TopicListCacheKey(TopicList... topicLists) { uuids = new UUID[topicLists.length]; for (int i = 0; i < uuids.length; i++) { uuids[i] = topicLists[i].getUuid(); } } @Override public int hashCode() { return Arrays.hashCode(uuids); } @Override public boolean equals(Object other) { if (other == this) return true; if (other instanceof TopicListCacheKey) return Arrays.equals(uuids, ((TopicListCacheKey) other).uuids); return false; } } I figure that there are 2^128 different UUIDs and I will probably have at most around 1,000,000 TokenList objects active in the application at any time. Given this, and the fact that the UUIDs are used combinatorially in cache keys, it seems that the chances of this producing the wrong result are vanishingly small. Nevertheless, I feel uneasy about going ahead with it as it just feels 'dirty'. Are there any reasons I should not use this system? Will the performance costs of the SecureRandom used by UUID.randomUUID() outweigh the gains (especially since I expect multiple threads to be doing this at the same time)? Are collisions going to be more likely than I think? Basically, is there anything wrong with doing it this way?? Thanks.

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• iPhone dev - viewDidUnload subviews

  - by Mk12

  I'm having a hard time undestand a couple of the methods in UIViewController, but first I'll say what I think they are meant for (ignoring interface builder because I'm not using it): -init: initialize non view-related stuff that won't need to be released in low memory situations (i.e. not objects or objects that can't be recreated easily). -loadView: create the view set the [self view] property. -viewDidLoad: Create all the other view elements -viewDidUnload: Release objects created in -viewDidLoad. didReceiveMemoryWarning: Low-memory situation, release unnecessary things such as cached data, if this view doesn't have a superview then the [super didReceiveMemoryWarning] will go on to release (unload) the view and call -viewDidUnload. -dealloc: release everything -viewWillAppear:, -viewDidAppear:, -viewWillDisappear:, -viewDidDisappear: self-explanatory, not necessary unless you want to respond (do something) to those events. I'm not sure about a couple of things. First, the Apple docs say that when -viewDidUnload is called, the view has already been released and set to nil. Will -loadView get called again to recreate the view later on? There's a few things I created in -viewDidLoad that I didn't make a ivar/property for because there is no need and it will be retained by the view (because they are subviews of it). So when the view is released, it will release those too, right? When the view is released, will it release all its subviews? Because all the objects I created in -viewDidLoad are subviews of [self view]. So if they already get released why release them again in -viewDidUnload? I can understand data that is necessary when the view is visible being loaded and unloaded in these methods, but like I asked, why release the subviews if they already get released? EDIT: After reading other questions, I think I might have got it (my 2nd question). In the situation where I just use a local variable, alloc it, make it a subview and release, it will have a retain count of 1 (from adding it as a subview), so when the view is released it is too. Now for the view elements with ivars pointing to them, I wasn't using properties because no outside class would need to access them. But now I think that that's wrong, because in this situation: // MyViewController.h @interface MyViewController : UIViewController { UILabel *myLabel; } // MyViewController.m . . . - (void)viewDidLoad { myLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 40, 10)]; [myLabel setText:@"Foobar"]; [[self view] addSubview:myLabel]; } - (void)viewDidUnload [ // equivalent of [self setMyLabel:nil]; without properties [myLabel release]; myLabel = nil; } In that situation, the label will be sent the -release message after it was deallocated because the ivar didn't retain it (because it wasn't a property). But with a property the retain count would be two: the view retaining it and the property. So then in -viewDidUnload it will get deallocated. So its best to just always use properties for these things, am I right? Or not? EDIT: I read somewhere that -viewDidLoad and -viewDidUnload are only for use with Interface Builder, that if you are doing everything programmatically you shouldn't use them. Is that right? Why?

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• NSOperation unable to load data on the TableView

  - by yeohchan

  I have a problem in NSOperation. I tried many ways but it would run behind the screen, but will not make it appear on the my table view. Can anyone help me out with this. I am new to NSOperation. Recents.h #import <UIKit/UIKit.h> #import "FlickrFetcher.h" @interface Recents : UITableViewController { FlickrFetcher *fetcher; NSString *name; NSData *picture; NSString *picName; NSMutableArray *names; NSMutableArray *pics; NSMutableArray *lists; NSArray *namelists; NSOperationQueue *operationQueue; } @property (nonatomic,retain)NSString *name; @property (nonatomic,retain)NSString *picName; @property (nonatomic,retain)NSData *picture; @property (nonatomic,retain)NSMutableArray *names; @property (nonatomic,retain)NSMutableArray *pics; @property(nonatomic,retain)NSMutableArray *lists; @property(nonatomic,retain)NSArray *namelists; @end Recents.m #import "Recents.h" #import "PersonList.h" #import "PhotoDetail.h" @implementation Recents @synthesize picName,picture,name,names,pics,lists,namelists; // The designated initializer. Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil { if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) { // Custom initialization self.title=@"Recents"; } return self; } - (void)beginLoadingFlickrData{ NSInvocationOperation *operation = [[NSInvocationOperation alloc] initWithTarget:self selector:@selector(synchronousLoadFlickrData) object:nil]; [operationQueue addOperation:operation]; [operation release]; } - (void)synchronousLoadFlickrData{ fetcher=[FlickrFetcher sharedInstance]; NSArray *recents=[fetcher recentGeoTaggedPhotos]; [self performSelectorOnMainThread:@selector(didFinishLoadingFlickrDataWithResults:) withObject:recents waitUntilDone:NO]; } - (void)didFinishLoadingFlickrDataWithResults:(NSArray *)recents{ for(NSDictionary *dic in recents){ [names addObject:[fetcher usernameForUserID:[dic objectForKey:@"owner"]]]; if([[dic objectForKey:@"title"]isEqualToString:@""]){ [pics addObject:@"Untitled"]; }else{ [pics addObject:[dic objectForKey:@"title"]]; } NSLog(@"OK!!"); } [self.tableView reloadData]; [self.tableView flashScrollIndicators]; } // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. - (void)viewDidLoad { [super viewDidLoad]; operationQueue = [[NSOperationQueue alloc] init]; [operationQueue setMaxConcurrentOperationCount:1]; [self beginLoadingFlickrData]; self.tableView.rowHeight = 95; } /* // Override to allow orientations other than the default portrait orientation. - (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation { // Return YES for supported orientations return (interfaceOrientation == UIInterfaceOrientationPortrait); } */ - (void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } - (void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } - (void)dealloc { [super dealloc]; } #pragma mark - #pragma mark Table View Data Source Methods - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { return[names count]; } - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath { static NSString *SimpleTableIdentifier = @"SimpleTableIdentifier"; UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:SimpleTableIdentifier]; if (cell == nil) { cell = [[[UITableViewCell alloc]initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:SimpleTableIdentifier] autorelease]; } cell.detailTextLabel.text=[names objectAtIndex:indexPath.row]; cell.textLabel.text=[pics objectAtIndex:indexPath.row]; //UIImage *image=[UIImage imageWithData:[self.lists objectAtIndex:indexPath.row]]; //cell.imageView.image=image; return cell; } - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath { fetcher=[[FlickrFetcher alloc]init]; PhotoDetail *scroll=[[PhotoDetail alloc]initWithNibName:@"PhotoDetail" bundle:nil]; scroll.titleName=[self.pics objectAtIndex:indexPath.row]; scroll.picture = [UIImage imageWithData:[self.lists objectAtIndex:indexPath.row]]; [self.navigationController pushViewController:scroll animated:YES]; }

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• [UIView didCreateWorkout:Type:Distance:Time:Message:]: unrecognized selector sent to instance.

  - by Stephen

  Hello, I'm getting the above error and have been looking at it all day, I'm getting no where fast. Anyone any ideas ? I'm new to IPhone Development. Code Below: #import "WorkoutViewController.h" #import "Workout.h" @implementation WorkoutViewController @synthesize workoutDelegate; //@synthesize Speed; //@synthesize Calories; @synthesize route; @synthesize type; @synthesize distance; @synthesize time; @synthesize message; @synthesize DBContents; @synthesize workoutArray; @synthesize managedObjectContext; //@synthesize saveWorkout; //@synthesize cancelWorkout; -(IBAction)hideKeyboard { } -(IBAction)saveWorkout { [workoutDelegate didCreateWorkout: route.text Type: type.text Distance: distance.text Time: time.text Message: message.text]; } -(IBAction)cancelWorkout { [self.workoutDelegate didCancelWorkout]; } // Implement viewDidLoad to do additional setup after loading the view, typically from a nib. -(void)viewDidLoad { //Set images for Save & Cancel buttons. UIImage *normalImage = [[UIImage imageNamed:@"whiteButton.png"] stretchableImageWithLeftCapWidth:12.0 topCapHeight:0.0]; [saveWorkout setBackgroundImage:normalImage forState:UIControlStateNormal]; [cancelWorkout setBackgroundImage:normalImage forState:UIControlStateNormal]; UIImage *pressedImage = [[UIImage imageNamed:@"blueButton.png"] stretchableImageWithLeftCapWidth:12.0 topCapHeight:0.0]; [saveWorkout setBackgroundImage:pressedImage forState:UIControlStateHighlighted]; [cancelWorkout setBackgroundImage:pressedImage forState:UIControlStateHighlighted]; //Fetch details from the database. NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Workout" inManagedObjectContext:managedObjectContext]; [request setEntity:entity]; NSError *error; self.workoutArray = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy]; [request release]; //self.workoutArray = [[NSMutableArray alloc] init]; //self.DBContents.text = [self.workoutArray objectAtIndex:0]; [super viewDidLoad]; } -(void)didReceiveMemoryWarning { // Releases the view if it doesn't have a superview. [super didReceiveMemoryWarning]; // Release any cached data, images, etc that aren't in use. } -(void)viewDidUnload { // Release any retained subviews of the main view. // e.g. self.myOutlet = nil; } -(void) didCreateWorkout:(NSString *)thisRoute Type:(NSString *)thisType Distance:(NSString *)thisDistance Time:(NSString *)thisTime Message:(NSString *)thisMessage { // Add the new workout. Workout *newWorkout = [NSEntityDescription insertNewObjectForEntityForName:@"Workout" inManagedObjectContext:self.managedObjectContext]; newWorkout.route = thisRoute; newWorkout.type = thisType; newWorkout.distance = thisDistance; newWorkout.time = thisTime; newWorkout.message = thisMessage; [self.workoutArray addObject:newWorkout]; //[self dismissModalViewControllerAnimated:YES]; } -(void)didCancelWorkout { [self dismissModalViewControllerAnimated:YES]; } -(void)dealloc { // [Speed release]; // [Calories release]; [route release]; [type release]; [distance release]; [time release]; [message release]; // [saveWorkout release]; // [cancelWorkout release]; [workoutArray release]; [managedObjectContext release]; [super dealloc]; } @end I'm trying to save details that I key on the screen (WorkoutViewController.xib) and I click the save button and get the above error. Thanks Stephen

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• Looking for a better design: A readonly in-memory cache mechanism

  - by Dylan Lin

  Hi all, I have a Category entity (class), which has zero or one parent Category and many child Categories -- it's a tree structure. The Category data is stored in a RDBMS, so for better performance, I want to load all categories and cache them in memory while launching the applicaiton. Our system can have plugins, and we allow the plugin authors to access the Category Tree, but they should not modify the cached items and the tree(I think a non-readonly design might cause some subtle bugs in this senario), only the system knows when and how to refresh the tree. Here are some demo codes: public interface ITreeNode<T> where T : ITreeNode<T> { // No setter T Parent { get; } IEnumerable<T> ChildNodes { get; } } // This class is generated by O/R Mapping tool (e.g. Entity Framework) public class Category : EntityObject { public string Name { get; set; } } // Because Category is not stateless, so I create a cleaner view class for Category. // And this class is the Node Type of the Category Tree public class CategoryView : ITreeNode<CategoryView> { public string Name { get; private set; } #region ITreeNode Memebers public CategoryView Parent { get; private set; } private List<CategoryView> _childNodes; public IEnumerable<CategoryView> ChildNodes { return _childNodes; } #endregion public static CategoryView CreateFrom(Category category) { // here I can set the CategoryView.Name property } } So far so good. However, I want to make ITreeNode interface reuseable, and for some other types, the tree should not be readonly. We are not able to do this with the above readonly ITreeNode, so I want the ITreeNode to be like this: public interface ITreeNode<T> { // has setter T Parent { get; set; } // use ICollection<T> instead of IEnumerable<T> ICollection<T> ChildNodes { get; } } But if we make the ITreeNode writable, then we cannot make the Category Tree readonly, it's not good. So I think if we can do like this: public interface ITreeNode<T> { T Parent { get; } IEnumerable<T> ChildNodes { get; } } public interface IWritableTreeNode<T> : ITreeNode<T> { new T Parent { get; set; } new ICollection<T> ChildNodes { get; } } Is this good or bad? Are there some better designs? Thanks a lot! :)

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• Is it possible to implement bitwise operators using integer arithmetic?

  - by Statement

  Hello World! I am facing a rather peculiar problem. I am working on a compiler for an architecture that doesn't support bitwise operations. However, it handles signed 16 bit integer arithmetics and I was wondering if it would be possible to implement bitwise operations using only: Addition (c = a + b) Subtraction (c = a - b) Division (c = a / b) Multiplication (c = a * b) Modulus (c = a % b) Minimum (c = min(a, b)) Maximum (c = max(a, b)) Comparisons (c = (a < b), c = (a == b), c = (a <= b), et.c.) Jumps (goto, for, et.c.) The bitwise operations I want to be able to support are: Or (c = a | b) And (c = a & b) Xor (c = a ^ b) Left Shift (c = a << b) Right Shift (c = a b) (All integers are signed so this is a problem) Signed Shift (c = a b) One's Complement (a = ~b) (Already found a solution, see below) Normally the problem is the other way around; how to achieve arithmetic optimizations using bitwise hacks. However not in this case. Writable memory is very scarce on this architecture, hence the need for bitwise operations. The bitwise functions themselves should not use a lot of temporary variables. However, constant read-only data & instruction memory is abundant. A side note here also is that jumps and branches are not expensive and all data is readily cached. Jumps cost half the cycles as arithmetic (including load/store) instructions do. On other words, all of the above supported functions cost twice the cycles of a single jump. Some thoughts that might help: I figured out that you can do one's complement (negate bits) with the following code: // Bitwise one's complement b = ~a; // Arithmetic one's complement b = -1 - a; I also remember the old shift hack when dividing with a power of two so the bitwise shift can be expressed as: // Bitwise left shift b = a << 4; // Arithmetic left shift b = a * 16; // 2^4 = 16 // Signed right shift b = a >>> 4; // Arithmetic right shift b = a / 16; For the rest of the bitwise operations I am slightly clueless. I wish the architects of this architecture would have supplied bit-operations. I would also like to know if there is a fast/easy way of computing the power of two (for shift operations) without using a memory data table. A naive solution would be to jump into a field of multiplications: b = 1; switch (a) { case 15: b = b * 2; case 14: b = b * 2; // ... exploting fallthrough (instruction memory is magnitudes larger) case 2: b = b * 2; case 1: b = b * 2; } Or a Set & Jump approach: switch (a) { case 15: b = 32768; break; case 14: b = 16384; break; // ... exploiting the fact that a jump is faster than one additional mul // at the cost of doubling the instruction memory footprint. case 2: b = 4; break; case 1: b = 2; break; }

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• Making a non-trivial Image and Video Gallery with a really nice interface

  - by Cawas

  Short part: I'm starting to build an Image and Video Gallery for our intranet. It's pretty much like an image gallery with video thumbnails that play on click. It's just good to keep that in mind because caching and streaming happen in very different ways there. It will serve to browse our reference database, which will also contain searching, tagging and voting. There are 3 features that I need to begin with: Quick preview of thumbnails from each Gallery Fast zoom in / out Animated scrolling Now to the long part, since I can't seem to reduce this: I hope this question belongs here. Maybe people can read this through and identify with it, specially since I expect answers to be pretty specific. The first plan was getting Apple's mobile me gallery as base, because it just so happens to have all those 3 features. If you've never seem it, you should check it out. Move the mouse over each collection and you'll get a nice preview "per pixel". Carousel got a really good scrolling, not just because of the pretty effect. I like it much more than cooliris, but it would be nice to have it in several rows, maybe without the magnifying effect... Then it could be all in the same place with the zoom. The more the features blend-in together, the better. Zooming out with the mouse, scrolling by dragging, once the zoom is really out it becomes a browsing through galleries, with the quick-show preview of each, all properly cached and fast. That'd be perfect. A very compelling interface will be important in this project. Well, my point here is just describing what I need and hope to hear from people with more experience in all that stuff of what's already done and what I'd have to do myself. And how (i.e. which framework to use) to do it. To begin with, I've found a gallery demo and its source code (I think it was from here, but the link seems broken now). I guess it was made in SproutCore, which is what mobileme was based upon. Definitely with JQuery (which already seems a little slow). But I'm still missing two features there: the carousel and the fast zoom (it's just not as slow as the zoom in this demo with cappuccino). Then I've found a supposedly better one with a pretty good and similar zoom, that I'm not sure if it's using any framework and is already in php. Right now it'd be better having just the HTML, no server-side, since I'm building interface first. So, can anyone point directions? There are way too many options! Should I look for another solution closer to what I need, or try and tweak this one? I'm not familiar with any framework at all. Sorry for bringing this question that I will have to answer myself anyway sooner or later and sorry that I couldn't make this smaller. Thanks.

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