recursive

appengine: counting more than 1000 entities

Wed, 26 Aug 2009 22:37:26 -0400

The best solution I’ve found for counting more than 1000 entities in appengine is in this thread (with a minor correction):

http://stackoverflow.com/questions/264154/google-appengine-how-to-fetch-more-than-1000/1338456#1338456

In my projects I’ve been creating a class called ModelHelper with this classmethod:

@classmethod
def count(cls, model_class):
    count = 0

    query = model_class.all(keys_only=True).order('__key__')
    while count % cls.MAX_FETCH == 0:
        current_count = query.count()
        if current_count == 0:
            break
        count += current_count

        if current_count == ModelHelper.MAX_FETCH:
            last_key = query.fetch(1, cls.MAX_FETCH - 1)[0]
            query = query.filter('__key__ > ', last_key)

    return count

where MAX_FETCH is set to 1000, of course.

linux networking: when eth0 becomes eth2

Mon, 25 May 2009 10:28:56 -0400

Today I boot my linux box and I have no network connectivity.

->matth@juggernaut ~ ? ping google.com
 ping: unknown host google.com

->matth@juggernaut ~ ? ifconfig
lo    Link encap:Local Loopback
      inet addr:127.0.0.1  Mask:255.0.0.0
      inet6 addr: ::1/128 Scope:Host
      UP LOOPBACK RUNNING  MTU:16436  Metric:1
      RX packets:967 errors:0 dropped:0 overruns:0 frame:0
      TX packets:967 errors:0 dropped:0 overruns:0 carrier:0
      collisions:0 txqueuelen:0
      RX bytes:155073 (151.4 KiB)  TX bytes:155073 (151.4 KiB)

Where is eth0?

->matth@juggernaut ~ ? sudo ifup eth0=eth0-static
SIOCSIFADDR: No such device
eth0: ERROR while getting interface flags: No such device
SIOCSIFNETMASK: No such device
SIOCSIFBRDADDR: No such device
eth0: ERROR while getting interface flags: No such device
eth0: ERROR while getting interface flags: No such device
Failed to bring up eth0-static.

I have 2 configs for eth0 in /etc/network/interfaces:

eth0-dhcp for dhcp
eth0-static using a static ip

(I prefer the latter, so my linux server can have a consistent internal IP).

For some reason, I try this:

->matth@juggernaut ~ ? ifconfig -a
eth2      Link encap:Ethernet  HWaddr 00:17:31:53:fa:1e
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
          Interrupt:22 Base address:0x4000

lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:980 errors:0 dropped:0 overruns:0 frame:0
          TX packets:980 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:161549 (157.7 KiB)  TX bytes:161549 (157.7 KiB)

What the hell is this eth2?

->matth@juggernaut ~ ? sudo ifup eth2=eth0-static
if-up.d/mountnfs[eth2]: waiting for interface eth0=eth0-static before doing NFS mounts (warning).

And then, everything worked. But why did my network device change to eth2?

regionset fixes "Failed to retrieve all CSS keys" errors.

Mon, 11 May 2009 16:05:36 -0400

I attempted to copy a DVD in K3b and watched it fail with this message:

Failed to retrieve all CSS keys

I checked ~/.dvdcss and saw some keys. I deleted it, retried, another fail.

I ran the command-line tool dvdbackup and saw similar errors:

libdvdread: Error cracking CSS key for /VIDEO_TS/VTS_28_1.VOB (0x002ee531)!!

I eventually stumbled upon some posts suggesting it may be a DVD region issue.

sudo apt-get install regionset

Then, as root, ran:

regionset /dev/dvd 1

Now I can burn Half Nelson.

one liner: adding all new files to svn

Sat, 11 Apr 2009 01:19:00 -0400

I forget and remember this about 20 times a year:

svn st | sed -n 's/\? *//p' | xargs svn add