[Ironpython-users] IronPython SQLite interface

Doug Blank doug.blank at gmail.com
Thu May 8 18:32:22 CEST 2014 

Just getting back to attempting to use sqlite3 on computers other than
Windows, and it looks like this C# library has other problems on other OSes.

The first issue is that it appears that all activity must happen in the
same thread (connection, cursor, execution). That can mitigated against if
that is the way that it has to be. (A wrapper could be supplied to run
everything in a specific thread).

The next problem is a show stopper:

import sqlite3
conn = sqlite3.connect("test.db")
cur = conn.cursor()
cur.execute("select * from tables;")

This works on Windows, but gives a SystemError: LockFileEx on Linux. I
suspect that the information that Ivan pointed to (below) indicates that
these patches screwed up sqlite port so that it no longer will work on
Linux and Mac.

Anyone have ideas, on either a fix, or using a different library, different
version?

-Doug



On Tue, Feb 11, 2014 at 8:25 AM, Ivan Pozdeev <vano at mail.mipt.ru> wrote:

> > Issue #173 with patch:
>
> > https://github.com/IronLanguages/main/issues/173
>
>
>
> > That works for me! I just removed the removal of the slash. I don't
> > know what that will do for Windows users that had a path that started
> with "/".
>
>
> > We distribute our own DLLs, so no rush for a new release.
>
>
> > Thanks!
>
>
> > -Doug
>
>
> > On Tue, Feb 11, 2014 at 4:39 AM, Jeff Hardy <jdhardy at gmail.com> wrote:
> >
> > On Mon, Feb 10, 2014 at 10:15 PM, Slide <slide.o.mix at gmail.com> wrote:
>   >> That seems a little odd. Perhaps Jeff can shed some light on it, I
> think he
>  >> wrote the SQLite adaptation layer.
> >
> >  I did, but the funny code is part of the C#-sqlite library, which is a
> >  port of the C library to C#. (if you're feeling brave, dig through the
> >  code. It's ... interesting.) It looks like the author just assumed
> >  Windows-ish systems in all cases, and Doug has to go and break
> >  everything by trying to run it on Unix. :(
> >
> The file is indeed os_win_c.cs while the original library
> (http://www.sqlite.org/cgi/src/tree?ci=trunk) has os_unix.c as well.
>
> The relevant change in csharp-sqlite is
>
> http://code.google.com/p/csharp-sqlite/source/detail?r=2fd39fa5400f6492b97617816c4f20a891b2e432&path=/Community.CsharpSqlite/src/os_win_c.cs
> with a rather evasive message "Initial 3.7.7 changes".
>
> It appears to be a bad port of the original sqlite diff 3.7.6.8->3.7.7
>
> http://www.sqlite.org/cgi/src/fdiff?v1=24d72407a9055196&v2=eafcd6b91cf204a7&sbs=1
>
> with related lines in it ultimately coming from changeset
> http://www.sqlite.org/cgi/src/info/fe57a8f621
> that clearly states "Have the xFullpath method in os_win.c discard the
> initial "/" if a filename begins with "/X:", where X is any alphabetic
> character"
> without explaining the cause.
>
> The branch is called `uri' so I guess it's needed to handle URIs
> like file:///C:/what/ya/mah/call/it.sqlite
> (Windows kernel APIs treat (and always treated) '/' and '\' the same
> (
> http://bytes.com/topic/python/answers/23123-when-did-windows-start-accepting-forward-slash-path-separator)).
>
>
>
> So, the code was clearly intended for Windows only but ultimately,
> it's csharp-sqlite's /bydlocode/ that broke things down in this
> particular case.
>
>
> >  I have no idea what that code is trying to do (context:
> >
> >
> https://github.com/IronLanguages/main/blob/master/Languages/IronPython/IronPython.SQLite/c%23sqlite/os_win_c.cs#L2646
> );
> >   it might be some vestigial part of SQLite that's not needed. Since //
> >  seems OK I'm assuming that's the case.
> >
> >  Doug, can you open an issue? And in the meantime, is using // an
> >  acceptable workaround?
> >
> >  - Jeff
> >
>
>  >>
>  >>
>  >> On Mon, Feb 10, 2014 at 3:14 PM, Doug Blank <doug.blank at gmail.com>
> wrote:
>  >>>
>  >>> That must be the issue, as "//home/dblank/name.db" works:
>  >>>
>  >>> $ ipy.exe
>  >>> IronPython 2.9.9a0 DEBUG (2.9.0.0) on Mono 4.0.30319.1 (64-bit)
>  >>> Type "help", "copyright", "credits" or "license" for more information.
>  >>> >>> import sqlite3
>  >>> >>> sqlite3.connect("//home/dblank/test.db")
>  >>> <Connection object at 0x000000000000002B>
>  >>> >>>
>  >>>
>  >>> -Doug
>  >>>
>  >>>
>  >>>
>  >>> On Mon, Feb 10, 2014 at 5:12 PM, Doug Blank <doug.blank at gmail.com>
> wrote:
>  >>>>
>  >>>> After more testing, it appears that it only fails when the path
> begins
>  >>>> with a slash "/".
>  >>>>
>  >>>> I see:
>  >>>>
>  >>>> ./c#sqlite/os_win_c.cs:      if ( zConverted.StartsWith( "/" ) &&
>  >>>> !zConverted.StartsWith( "//"
>  >>>>
>  >>>> I'll try a couple of more things...
>  >>>>
>  >>>> -Doug
>  >>>>
>  >>>>
>  >>>> On Mon, Feb 10, 2014 at 9:19 AM, Doug Blank <doug.blank at gmail.com>
> wrote:
>  >>>>>
>  >>>>>
>  >>>>> On Mon, Feb 10, 2014 at 8:47 AM, Slide <slide.o.mix at gmail.com>
> wrote:
>  >>>>>>
>  >>>>>> All the connect call does is this:
>  >>>>>>
>  >>>>>> int rc = Sqlite3.sqlite3_open(database, out this.db);
>  >>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>> if(rc != Sqlite3.SQLITE_OK)
>  >>>>>>     throw GetSqliteError(this.db, null);
>  >>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>> Which makes me thing that sqlite3_open is returning an error code.
> What
>  >>>>>> happens if you do the same in CPython?
>  >>>>>
>  >>>>>
>  >>>>> No error, creates a file of length 0, and works:
>  >>>>>
>  >>>>> $ python
>  >>>>> Python 2.7.5+ (default, Sep 19 2013, 13:48:49)
>  >>>>> [GCC 4.8.1] on linux2
>  >>>>> Type "help", "copyright", "credits" or "license" for more
> information.
>  >>>>> >>> import sqlite3
>  >>>>> >>> sqlite3.connect("/home/dblank/test.db")
>  >>>>> <sqlite3.Connection object at 0x7fc3c21b6118>
>  >>>>> >>>
>  >>>>>
>  >>>>> $ ls -al /home/dblank/test.db
>  >>>>> -rw-r--r-- 1 dblank dblank 0 Feb 10 09:15 /home/dblank/test.db
>  >>>>>
>  >>>>> -Doug
>  >>>>>
>  >>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>> On Fri, Feb 7, 2014 at 6:01 AM, Doug Blank <doug.blank at gmail.com>
>  >>>>>> wrote:
>  >>>>>>>
>  >>>>>>>
>  >>>>>>> On Fri, Feb 7, 2014 at 7:47 AM, Slide <slide.o.mix at gmail.com>
> wrote:
>  >>>>>>>>
>  >>>>>>>> Do you get a specific error message?
>  >>>>>>>
>  >>>>>>>
>  >>>>>>> Sorry, yes:
>  >>>>>>>
>  >>>>>>> Traceback (most recent call last):
>  >>>>>>>   File "<string>", line 1, in <module>
>  >>>>>>> _sqlite3.OperationalError: unable to open database file
>  >>>>>>>
>  >>>>>>> Does this work for you? I get this error running latest ipy.exe
> (Mono
>  >>>>>>> 2.10, Ubuntu 13.10) and IronPython in Calico.
>  >>>>>>>
>  >>>>>>> -Doug
>  >>>>>>>
>  >>>>>>>
>  >>>>>>>>
>  >>>>>>>>
>  >>>>>>>>
>  >>>>>>>> On Fri, Feb 7, 2014 at 5:37 AM, Doug Blank <doug.blank at gmail.com
> >
>  >>>>>>>> wrote:
>  >>>>>>>>>
>  >>>>>>>>> Just recently discovered the sqlite3 port for IronPython, but
> having
>  >>>>>>>>> some basic trouble:
>  >>>>>>>>>
>  >>>>>>>>> This works fine:
>  >>>>>>>>>
>  >>>>>>>>> import sqlite3
>  >>>>>>>>> sqlite3.connect("test.db")
>  >>>>>>>>>
>  >>>>>>>>> but this doesn't:
>  >>>>>>>>>
>  >>>>>>>>> import sqlite3
>  >>>>>>>>> sqlite3.connect("/home/dblank/test.db")
>  >>>>>>>>>
>  >>>>>>>>> Any ideas?
>  >>>>>>>>>
>  >>>>>>>>> -Doug
>  >>>>>>>>>
>  >>>>>>>>>
>  >>>>>>>>> _______________________________________________
>  >>>>>>>>> Ironpython-users mailing list
>  >>>>>>>>> Ironpython-users at python.org
>  >>>>>>>>> https://mail.python.org/mailman/listinfo/ironpython-users
>  >>>>>>>>>
>  >>>>>>>>
>  >>>>>>>>
>  >>>>>>>>
>  >>>>>>>> --
>  >>>>>>>> Website: http://earl-of-code.com
>  >>>>>>>
>  >>>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>>
>  >>>>>> --
>  >>>>>> Website: http://earl-of-code.com
>  >>>>>>
>  >>>>>> _______________________________________________
>  >>>>>> Ironpython-users mailing list
>  >>>>>> Ironpython-users at python.org
>  >>>>>> https://mail.python.org/mailman/listinfo/ironpython-users
>  >>>>>>
>  >>>>>
>  >>>>
>  >>>
>  >>
>  >>
>  >>
>  >> --
>  >> Website: http://earl-of-code.com
>  >>
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>  >>
> >
>
>
>
>
> --
> Best regards,
>  Ivan                            mailto:vano at mail.mipt.ru
>
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