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Differential D1866

transaction: register summary callbacks only at start of transaction (BC)
ClosedPublic

Authored by martinvonz on Jan 16 2018, 2:33 AM.

Details

Reviewers
yuja
Group Reviewers
hg-reviewers
Commits
rHG03e921942163: transaction: register summary callbacks only at start of transaction (BC)
Summary

We currently register summary callbacks every time
localrepo.transaction() is called, so both when the transaction is
started and when a nested transaction is created. That seems a little
weirdly asymmetric, because the summary callbacks are thus not
necessarily registred at the beginning of the outermost transaction,
but they are only called when the outermost transaction closes (not
when a nested transaction closes).

I want to add another summary callback that records the repo state at
the beginning of the transaction and compares to that when the
transaction closes. However, because of the registration that happens
when a nested transaction is created, that would need to go through
extra trouble to not overwrite the callback and report the difference
from the start time of the innermost transaction to the close of the
outermost transaction.

Also, the callbacks are registered with a name based on the order they
are defined in the registersummarycallback(). For example, if both the
"new changesets %s" and the "obsoleted %i changesets" hooks are
registered, the first would be called 00-txnreport and the second
would be called 01-txnreport. That gets really weird if
registersummarycallback() gets called multiple times, because the last
one wins, and a depending on which of the two callbacks get
registered, we might hypothetically even overwrite on type of callback
with another. For example, if when the outer transaction was started,
we registered the "new changesets %s" callback first, and when the
inner transaction was started, we registered only the "obsoleted %i
changesets" callback, then only the latter message would get
printed. What makes it hypothetical is that what gets registered
depends on the transaction name, and the set of transaction names that
we match on for the former latter message is a subset of the set of
names we match on for the former. Still, that seems like a bug waiting
to happen.

That second issue could be solved independently, but the first issue
seems enough for me to consider it a bug (affecting developers, not
users), so this patch simply drops that extra registration.

Note that this affects "hg transplant" in a user-visible way. When "hg
transplant" is asked to transplant from a remote repo so it involves a
pull, then the outermost transaction name is "transplant" and an inner
transaction is created for "pull". That inner transaction is what led
us to sometimes report "new changesets %s" from "hg transplant". After
this patch, that no longer happens. That seems fine to me. We can make
it instead print the message for all "hg transplant" invocations if we
want (not just those involving a remote), but I'll leave that for
someone else to do if they think it's important.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

martinvonz created this revision.Jan 16 2018, 2:33 AM
yuja accepted this revision.Jan 18 2018, 8:14 AM
This revision is now accepted and ready to land.Jan 18 2018, 8:14 AM
Closed by commit rHG03e921942163: transaction: register summary callbacks only at start of transaction (BC) (authored by martinvonz). · Explain WhyJan 18 2018, 8:41 AM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

Diff 4897

mercurial/localrepo.py

def transaction(self, desc, report=None): def transaction(self, desc, report=None):
if (self.ui.configbool('devel', 'all-warnings') if (self.ui.configbool('devel', 'all-warnings')
or self.ui.configbool('devel', 'check-locks')): or self.ui.configbool('devel', 'check-locks')):
if self._currentlock(self._lockref) is None: if self._currentlock(self._lockref) is None:
raise error.ProgrammingError('transaction requires locking') raise error.ProgrammingError('transaction requires locking')
tr = self.currenttransaction() tr = self.currenttransaction()
if tr is not None: if tr is not None:
scmutil.registersummarycallback(self, tr, desc)
return tr.nest() return tr.nest()
# abort here if the journal already exists # abort here if the journal already exists
if self.svfs.exists("journal"): if self.svfs.exists("journal"):
raise error.RepoError( raise error.RepoError(
_("abandoned transaction found"), _("abandoned transaction found"),
hint=_("run 'hg recover' to clean up transaction")) hint=_("run 'hg recover' to clean up transaction"))

tests/test-transplant.t

searching for changes searching for changes
searching for changes searching for changes
adding changesets adding changesets
adding manifests adding manifests
adding file changes adding file changes
added 1 changesets with 1 changes to 1 files added 1 changesets with 1 changes to 1 files
applying a53251cdf717 applying a53251cdf717
a53251cdf717 transplanted to 8d9279348abb a53251cdf717 transplanted to 8d9279348abb
new changesets 37a1297eb21b:8d9279348abb
$ hg log --template '{rev} {parents} {desc}\n' $ hg log --template '{rev} {parents} {desc}\n'
2 b3 2 b3
1 b1 1 b1
0 r1 0 r1
remote transplant without pull remote transplant without pull
(It was using "2" and "4" (as the previous transplant used to) which referenced (It was using "2" and "4" (as the previous transplant used to) which referenced
revision different from one run to another) revision different from one run to another)
searching for changes searching for changes
searching for changes searching for changes
adding changesets adding changesets
adding manifests adding manifests
adding file changes adding file changes
added 2 changesets with 2 changes to 2 files added 2 changesets with 2 changes to 2 files
applying a53251cdf717 applying a53251cdf717
4:a53251cdf717 merged at 4831f4dc831a 4:a53251cdf717 merged at 4831f4dc831a
new changesets 722f4667af76:4831f4dc831a
test interactive transplant test interactive transplant
$ hg --config extensions.strip= -q strip 0 $ hg --config extensions.strip= -q strip 0
$ hg -R ../t log -G --template "{rev}:{node|short}" $ hg -R ../t log -G --template "{rev}:{node|short}"
@ 4:a53251cdf717 @ 4:a53251cdf717
| |
o 3:722f4667af76 o 3:722f4667af76