So the straw man solution we've implemented for now looks like this.
(Background: we have a settings.THREADLOCALS construct which serves in a
capacity similar to Ned's global requests; also, our monkeypatch_method
decorator does what you probably think it does.) First, we've a tiny bit of
middleware:
from django.conf import settings
class RequestURIMiddleware:
"""
Set the request URI in THREADLOCALS so that it can be used to comment
SQL queries with what triggered them.
"""
def process_request(self, request):
settings.THREADLOCALS.request_uri = request.build_absolute_uri()
And then we've monkeypatched the cursor method on BaseDatabaseWrapper like
so:
from django.conf import settings
from django.db.backends import BaseDatabaseWrapper, util
from patchers import monkeypatch_method
import traceback
class CommentingCursorWrapper(util.CursorDebugWrapper):
def execute(self, sql, *args, **kwargs):
"""
Before sending to the DB, this adds a comment to the SQL with notes
about the query's origin
"""
try:
if getattr(settings, 'SQL_COMMENTS_ALWAYS_TRACEBACK', False):
raise AttributeError
# THREADLOCALS.request_uri is (usually) populated by
RequestURIMiddleware
origin_comment = ' /* Originated from request to
{0}'.format(settings.THREADLOCALS.request_uri)
except AttributeError:
# If no URI available (e.g., Celery task), report the first
non-Django point in the call stack:
tb = reversed(traceback.format_stack()[:-1]) # walk it bottom-up,
excluding this frame
for frame in tb:
if 'django' not in frame:
origin_comment = ' /* Originated
at{0}'.format(frame.split('\n')[0])
break
origin_comment = origin_comment.replace('%', '%%')
origin_comment = origin_comment.replace('*/', '\*\/')
sql += origin_comment + ' */'
return self.cursor.execute(sql, *args, **kwargs)
@monkeypatch_method(django.db.backends.BaseDatabaseWrapper)
def cursor(self, *args, **kwargs):
return CommentingCursorWrapper(cursor._original_cursor_function(self,
*args, **kwargs), self)
So in short, we comment the SQL with the URI when it's available, and fall
back to the (presumably more expensive to gather) traceback information
when it's not.
This is just the monkeypatch we're throwing in to solve our immediate
problem, but it'd be easy enough to convert into a patch. Before we do, any
thoughts/criticisms of this approach?
Best,
Marty
http://www.mapmyfitness.com/profile/woodlee/
On Monday, October 22, 2012 11:23:47 PM UTC-5, Matt McClure wrote:
>
> Thanks, Russell. That's similar to the approach we were thinking of
> implementing. Hopefully we'll have a straw man to share shortly.
>
> Matt
>
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