This is the mail archive of the
mailing list for the Cygwin project.
Re: [TEST] sqlite3-3.7.17-1 (Cygwin 1.7.19 locking feature)
- From: Warren Young <warren at etr-usa dot com>
- To: cygwin at cygwin dot com
- Date: Wed, 05 Jun 2013 14:06:10 -0600
- Subject: Re: [TEST] sqlite3-3.7.17-1 (Cygwin 1.7.19 locking feature)
- References: <51ACF886 dot 10301 at etr-usa dot com> <51AD3BB4 dot 2010601 at acm dot org> <20130604084128 dot GB19572 at calimero dot vinschen dot de> <20130604093749 dot GA32667 at calimero dot vinschen dot de>
On 6/4/2013 03:37, Corinna Vinschen wrote:
It would be nice to have a simple testcase (plain C, only Cygwin
POSIX calls, self-contained, yada yada) to see what sqlite expects in
POSIX lock mode.
SQLite locking is a hairball. It is spread over a range of about 2.5
kLOC within the 140 kLOC sqlite3.c file, and those routines are behind
about three layers of indirection from the mainline SQLite code.
Mind, I'm not talking about the *callers* of this code here, just the
locking routines themselves. Add in all the callers and *their*
I think we have to define the problem as "SQLite locking requires what
SQLite requires today."
Luckily, while creating the -2 packages, I stumbled across a STC in SQL
that replicates the reported problem:
$ ./sqlite3 foo.db 'create table fred(id integer, barney text)'
$ CYGWIN_SQLITE_LOCKING=posixmand ./sqlite3 foo.db \
'insert into fred(barney) values("wilma")'
If you change the locking mode to either "bsd" or "posix", it doesn't
fail. This gives hope that your new flock() implementation may work for us.
Here's hoping you can get the info you want from running the second
command under strace.
I can tell you that it doesn't fail if you don't do a DB write. For
example, this succeeds regardless of locking strategy:
$ ./sqlite3 foo.db .q
You can see it open the DB file and turn on mandatory locking, but since
it doesn't write to the DB file, it doesn't actually call flock(). The
same goes for the other two locking strategies.
Problem reports: http://cygwin.com/problems.html
Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple