I was think­ing: how can I im­ple­ment page pre­views in Bartle­Blog?

The ob­vi­ous way is to ren­der the page and open the lo­cal file. How­ev­er, the page may link or in­clude pieces that are not up­dat­ed yet in the stat­ic ver­sion, so that can give con­fus­ing re­sult­s.

Then it hit me... gen­er­ate the page on the fly and serve it. And do the same for ev­ery­thing else the brows­er asks for.

So, af­ter search­ing for 15 min­utes for the sim­plest python "web frame­work" that let me use the code al­ready in Bartle­blog, and de­cid­ing for Col­u­brid...

Now, this is cute: bartle­blog as a dy­nam­ic web app in 34 lines.

from colubrid import RegexApplication, HttpResponse, execute

from BartleBlog.backend.blog import Blog
import BartleBlog.backend.dbclasses as db
import os, codecs

class webBlog(Blog):
    def __init__(self):
        Blog.__init__(self)
        self.basepath='http://localhost:8080/'
        self.dest_dir=os.path.expanduser("~/.bartleblog/preview")
        if not os.path.isdir(self.dest_dir):
            os.mkdir(self.dest_dir)


class MyApplication(RegexApplication):
    blog=webBlog()
    urls = [
        (r'^(.*?)$', 'page'),
        (r'^(.*?)/(.*?)$', 'page'),
        (r'^(.*?)/(.*?)/(.*?)$', 'page'),
        (r'^(.*?)/(.*?)/(.*?)/(.*?)$', 'page')
    ]

    def page(self, *args):
        path=''.join(args)
        page=db.pageByPath(path)
        self.blog.renderPage(page)
        return HttpResponse(codecs.open(os.path.join(self.blog.dest_dir, path)).read())

app = MyApplication
app = StaticExports(app, {
    '/static': './static'
})


if __name__ == '__main__':
    execute(app)

Since the very be­gin­ning, Bartle­Blog has been us­ing Cher­ry­Tem­plate for its out­put for­mat­ting need­s. I like it, be­cause it's very sim­ple.

How­ev­er, it had grown rather cum­ber­some.

Specif­i­cal­ly, most pages in a blog are sort of a page tem­plate with a body tem­plate in­side (the main con­tent).

To do that on Cher­ry­Tem­plate, I used a two-­pass ap­proach: gen­er­ate the body, then pass it as pa­ram­e­ter to the page tem­plate.

Which is a pain in some cas­es be­cause you end ba­si­cal­ly hav­ing to do a ren­der­ing func­tion for each kind of page, or some crazy-evil func­tion (what I did).

Ex­plor­ing the dif­fer­ent python tem­plate en­gi­nes, I ran in­to Mako and de­cid­ed to give it a whirl. It looks good.

The ap­proach is a bit dif­fer­en­t, it is much more pow­er­ful, but you can still use it sim­ply if you can.

And the main fea­ture was tem­plate in­her­i­tance. Us­ing that, no more in­ner and out­er tem­plates, baby!

Oh, and per­for­mance is bet­ter:

Cherry

real    31m44.732s
user    21m18.336s
sys     2m7.628s


Mako

real    24m54.472s
user    19m9.508s
sys     1m56.375s

This is for com­plete­ly reren­der­ing the whole 7 years, 574 post­s, 40 stat­ic ar­ti­cles, 14 cat­e­go­ry blog, and there is tons of op­ti­miza­tions to be done.

BTW: this is how you reren­der the whole blog:

from BartleBlog.backend.blog import Blog
Blog().renderFullBlog()

I am work­ing on chang­ing Bartle­Blog so it can be used from scratch. That may sound odd but be­cause I have been us­ing it since day 2 to post this blog, it has grown very or­gan­i­cal­ly, mean­ing there are things that on­ly work be­cause of the way I used it while de­vel­op­ing it.

So, I cre­at­ed a test user, and cre­at­ed a test blog there, and I am work­ing, and de­cide to do an­oth­er from-scratch test, and...

I delet­ed my pro­duc­tion copy.

Yes. The one that gen­er­ates this blog. So this blog dis­ap­peared. Be­cause I used the wrong ter­mi­nal win­dow.

And I had one-week old back­up­s.

So I felt very very stupid.

Be­cause un­delet­ing in Lin­ux is a joke.

So I was think­ing how to spend a few hours recre­at­ing the last week of post­s, and what­ev­er, when I no­ticed on the taskbar... bartle­blog was still run­ning.

Which means that the DB was still open by a process. Which mean­s...

[ralsina@monty bartleblog]$ ps ax | grep python
17063 pts/1    S     24:33 python bartleblog.py
17161 ?        S      0:04 konqueror [kdeinit] -mimetype text/html http://www.google.com/search?q=python+copy+file&ie=UTF-8&oe=UTF-8
17454 pts/1    D+     0:00 grep python
[ralsina@monty bartleblog]$ su
Password:
[root@monty bartleblog]# cd /proc/17063/fd
[root@monty fd]# ls
0  1  10  11  12  2  3  4  5  6  7  8  9
[root@monty fd]# ls -l
total 0
lrwx------ 1 ralsina users 64 2007-05-13 21:07 0 -> /dev/pts/1
lrwx------ 1 ralsina users 64 2007-05-13 21:07 1 -> /dev/pts/1
lrwx------ 1 ralsina users 64 2007-05-13 21:07 10 -> socket:[159486]
lrwx------ 1 ralsina users 64 2007-05-13 21:07 11 -> socket:[159488]
lrwx------ 1 ralsina users 64 2007-05-13 21:07 12 -> /mnt/centos/home/ralsina/.bartleblog/blog.db (deleted)
lrwx------ 1 ralsina users 64 2007-05-13 21:07 2 -> /dev/pts/1
lr-x------ 1 ralsina users 64 2007-05-13 21:07 3 -> /mnt/centos/home/ralsina/Desktop/proyectos/bartleblog/bartleblog/BartleBlog/ui/bartleblog.py
lr-x------ 1 ralsina users 64 2007-05-13 21:07 4 -> pipe:[159481]
l-wx------ 1 ralsina users 64 2007-05-13 21:07 5 -> pipe:[159481]
lr-x------ 1 ralsina users 64 2007-05-13 21:07 6 -> pipe:[159482]
l-wx------ 1 ralsina users 64 2007-05-13 21:07 7 -> pipe:[159482]
lr-x------ 1 ralsina users 64 2007-05-13 21:07 8 -> pipe:[159485]
l-wx------ 1 ralsina users 64 2007-05-13 21:07 9 -> pipe:[159485]
[root@monty fd]# cp 12 /root/db
[root@monty fd]# ls -l ~/db
-rw-r--r-- 1 root root 3582976 2007-05-13 21:07 /root/db
[root@monty fd]# sqlitebrowser ~/db
[root@monty fd]# cp ~/db /home/ralsina/.bartleblog/blog.db

And I got the data­base back.

If you don't un­der­stand how that worked.... here's the ex­pla­na­tion:

• On unix, files are re­al­­ly un­linked (re­­moved from di­rec­­to­ries) when no process has them open. Even then, the da­­ta is not delet­ed, but find­­ing it is much hard­er.

• On /proc/PID you can see the file de­scrip­­tors each process has open.

• You can ac­­tu­al­­ly copy a file de­scrip­­tor.

So I went and copied the open file. And got it back. And this blog did­n't go away.

So I am luck­y! Stupid. But luck­y!

Took a while to im­ple­men­t, but Bartle­Blog fi­nal­ly got a func­tion­al menu ed­i­tor:

Right now, it on­ly works with the mootool­s-based menu gad­get, but I will start work­ing on the ya­hoo menu ver­sion in a mo­men­t.

The on­ly thing not work­ing is the pre­view but­ton, be­cause it needs more sup­port on the back­end side.

It's re­mark­ably easy to turn your QTextBrows­er in­to a lim­it­ed web browser, at least good enough to show im­ages from the we­b.

Here's all the code:

from PyQt4 import QtCore,QtGui
import urllib, os, md5

class PBrowser(QtGui.QTextBrowser):
    def loadResource(self, type, name):
        url=unicode(name.toString())
        ret=QtCore.QVariant()
        if url.startswith('http://'):
            dn=os.path.expanduser('~/.bartleblog/cache/')
            if not os.path.isdir(dn):
                os.mkdir(dn)
            m=md5.new()
            m.update(url)
            fn=os.path.join(dn,m.hexdigest())
            if not os.path.isfile(fn):
                urllib.urlretrieve(url, fn)
            ret=QtGui.QTextBrowser.loadResource(self, type, QtCore.QUrl(fn))
        else:
            ret=QtGui.QTextBrowser.loadResource(self, type, name)
        return ret

And here's bartle­blog tak­ing ad­van­tage of it:

It even has a prim­i­tive cache and ev­ery­thing ;-)