Re: [Zope-dev] kudos...
On Aug 8, 2011, at 4:44 PM, Chris McDonough wrote: Kudos to whomever turned the transaction package's transaction manager into a context manager and was thoughtful enough to provide the attempts method (which returns a separate context manager, wrapping the txn context manager, and retries some number of configurable times). This makes writing code that integrates with a web system that commits or aborts as easy as: import transaction for attempt in transaction.attempts(attempts): with attempt as t: response = handler(request) if t.isDoomed(): t.abort() if commit_veto is not None: veto = commit_veto(request, response) veto and t.abort() return response Very nice. - C Yes, this is *very* convenient and I like to use it, but beware of the bug (it's not affecting you above because of the return). According to the documentation, it's intended as a replacement for: for i in range(3): try: with transaction: ... some something ... except SomeTransientException: continue else: break So, presumably, for attempt in transanction.attempts(retries): with attempt as tx: do_something() should break after the *first* successful commit. It doesn't. Instead, it commits do_something() ``retries`` times which is most probably not intended. See https://bugs.launchpad.net/transaction/+bug/724332 The patch attached to the bug report is just a test that proves that behavior is unexpected and gives a workaround. The workaround is simple enough and I prefer to use transaction.attempts convenience rather than the typical try-except code above. Still, we really should find time to fix this in the transaction manager code so that it behaves as expected. (Or change the documentation and tests). Regards, Zvezdan ___ Zope-Dev maillist - Zope-Dev@zope.org https://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - https://mail.zope.org/mailman/listinfo/zope-announce https://mail.zope.org/mailman/listinfo/zope )
Re: [Zope-dev] kudos...
On Tue, 2011-08-09 at 11:48 -0400, Zvezdan Petkovic wrote:
On Aug 8, 2011, at 4:44 PM, Chris McDonough wrote:
Kudos to whomever turned the transaction package's transaction manager
into a context manager and was thoughtful enough to provide the attempts
method (which returns a separate context manager, wrapping the txn context
manager, and retries some number of configurable times).
This makes writing code that integrates with a web system that commits
or aborts as easy as:
import transaction
for attempt in transaction.attempts(attempts):
with attempt as t:
response = handler(request)
if t.isDoomed():
t.abort()
if commit_veto is not None:
veto = commit_veto(request, response)
veto and t.abort()
return response
Very nice.
- C
Yes, this is *very* convenient and I like to use it, but beware of the bug
(it's not affecting you above because of the return).
According to the documentation, it's intended as a replacement for:
for i in range(3):
try:
with transaction:
... some something ...
except SomeTransientException:
continue
else:
break
So, presumably,
for attempt in transanction.attempts(retries):
with attempt as tx:
do_something()
should break after the *first* successful commit.
It doesn't. Instead, it commits do_something() ``retries`` times which is
most probably not intended.
Not sure about that; I just return a value if it succeeds. I wouldnt
expect it to know to break out of the loop without a return in there.
I wound up with this, FWIW:
def tm_tween_factory(handler, registry, transaction=transaction):
# transaction parameterized for testing purposes
commit_veto = registry.settings.get('pyramid_tm.commit_veto',
default_commit_veto)
attempts = int(registry.settings.get('pyramid_tm.attempts', 1))
if not commit_veto:
commit_veto = None
else:
commit_veto = resolver.maybe_resolve(commit_veto)
def tm_tween(request):
if 'repoze.tm.active' in request.environ:
# don't handle txn mgmt if repoze.tm is in the WSGI pipeline
return handler(request)
try:
for attempt in transaction.attempts(attempts):
with attempt as t:
# make_body_seekable will copy wsgi.input if
# necessary, otherwise it will rewind the copy
# to position zero
if attempts != 1:
request.make_body_seekable()
response = handler(request)
if t.isDoomed():
raise AbortResponse(response)
if commit_veto is not None:
veto = commit_veto(request, response)
if veto:
raise AbortResponse(response)
return response
except AbortResponse, e:
return e.response
return tm_tween
A little more verbose but still nice.
See https://bugs.launchpad.net/transaction/+bug/724332
The patch attached to the bug report is just a test that proves that behavior
is unexpected and gives a workaround.
The workaround is simple enough and I prefer to use transaction.attempts
convenience rather than the typical try-except code above.
Still, we really should find time to fix this in the transaction manager code
so that it behaves as expected. (Or change the documentation and tests).
Regards,
Zvezdan
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[Zope-dev] zope-tests - FAILED: 4, OK: 35, UNKNOWN: 3
This is the summary for test reports received on the zope-tests list between 2011-08-08 00:00:00 UTC and 2011-08-09 00:00:00 UTC: See the footnotes for test reports of unsuccessful builds. An up-to date view of the builders is also available in our buildbot documentation: http://docs.zope.org/zopetoolkit/process/buildbots.html#the-nightly-builds Reports received Bluebream / Python2.4.6 64bit linux Bluebream / Python2.5.5 64bit linux Bluebream / Python2.6.5 64bit linux [1]FAILED (errors=1) : Zope-2.13-alltests Python-2.6.6 : Linux [2]UNKNOWN : Zope-2.12-alltests Python-2.6.6 : Linux [3]UNKNOWN : winbot / ZODB_dev py_270_win32 ZTK 1.0 / Python2.4.6 Linux 64bit ZTK 1.0 / Python2.5.5 Linux 64bit ZTK 1.0 / Python2.6.5 Linux 64bit [4]ZTK 1.0dev / Python2.4.6 Linux 64bit [5]ZTK 1.0dev / Python2.5.5 Linux 64bit [6]ZTK 1.0dev / Python2.6.5 Linux 64bit Zope 3.4 KGS / Python2.4.6 64bit linux Zope 3.4 KGS / Python2.5.5 64bit linux Zope 3.4 Known Good Set / py2.4-32bit-linux Zope 3.4 Known Good Set / py2.4-64bit-linux Zope 3.4 Known Good Set / py2.5-32bit-linux Zope 3.4 Known Good Set / py2.5-64bit-linux Zope-2.10 Python-2.4.6 : Linux Zope-2.11 Python-2.4.6 : Linux Zope-2.12 Python-2.6.6 : Linux Zope-2.13 Python-2.6.6 : Linux Zope-trunk Python-2.6.6 : Linux Zope-trunk-alltests Python-2.6.6 : Linux winbot / ZODB_dev py_254_win32 winbot / ZODB_dev py_265_win32 winbot / ZODB_dev py_265_win64 winbot / ZODB_dev py_270_win64 [7]winbot / zope.app.interface_py_265_32 winbot / ztk_10 py_254_win32 winbot / ztk_10 py_265_win32 winbot / ztk_10 py_265_win64 winbot / ztk_11 py_254_win32 winbot / ztk_11 py_265_win32 winbot / ztk_11 py_265_win64 winbot / ztk_11 py_270_win32 winbot / ztk_11 py_270_win64 winbot / ztk_dev py_254_win32 winbot / ztk_dev py_265_win32 winbot / ztk_dev py_265_win64 winbot / ztk_dev py_270_win32 winbot / ztk_dev py_270_win64 Non-OK results -- [1]UNKNOWN FAILED (errors=1) : Zope-2.13-alltests Python-2.6.6 : Linux https://mail.zope.org/pipermail/zope-tests/2011-August/047939.html [2]UNKNOWN UNKNOWN : Zope-2.12-alltests Python-2.6.6 : Linux https://mail.zope.org/pipermail/zope-tests/2011-August/047937.html [3]UNKNOWN UNKNOWN : winbot / ZODB_dev py_270_win32 https://mail.zope.org/pipermail/zope-tests/2011-August/047919.html [4]FAILED ZTK 1.0dev / Python2.4.6 Linux 64bit https://mail.zope.org/pipermail/zope-tests/2011-August/047927.html [5]FAILED ZTK 1.0dev / Python2.5.5 Linux 64bit https://mail.zope.org/pipermail/zope-tests/2011-August/047929.html [6]FAILED ZTK 1.0dev / Python2.6.5 Linux 64bit https://mail.zope.org/pipermail/zope-tests/2011-August/047928.html [7]FAILED winbot / zope.app.interface_py_265_32 https://mail.zope.org/pipermail/zope-tests/2011-August/047930.html ___ Zope-Dev maillist - Zope-Dev@zope.org https://mail.zope.org/mailman/listinfo/zope-dev ** No cross posts or HTML encoding! ** (Related lists - https://mail.zope.org/mailman/listinfo/zope-announce https://mail.zope.org/mailman/listinfo/zope )
