It is easier to reason about certain algorithms in terms of a
file->action mapping than the current action->list-of-files. Bid merge
is already written this way (but with a list of actions per file), and
largefiles' overridecalculateupdates() will also benefit. However,
that requires us to have at most one action per file. That requirement
is currently violated by 'dr' (divergent rename) and 'rd' (rename and
delete) actions, which can exist for the same file as some other
action.
These actions are only used for displaying warnings to the user; they
don't change anything in the working copy or the dirstate. In this
way, they are similar to the 'k' (keep) action. However, they are even
less action-like than 'k' is: 'k' at least describes what to do with
the file ("do nothing"), while 'dr' and 'rd' or only annotations for
files for which there may exist other, "real" actions.
As a first step towards separating these acitons out, stop including
them in the progress output, just like we already exclude the 'k'
action.
Most merge action messages don't describe the action itself, they
describe the reason the action was taken. The only exeption is the 'k'
action, for which the message is just "keep" and instead there is a
code comment folling it that says "remote unchanged". Let's move that
comment into the merge action message.
We can further limit the scope of the 2-way merge case by breaking out
the case where the file was not created from scratch on both sides but
rather renamed in the same way (and is therefore a 3-way merge). This
involves copying some code, but it makes it clearer which case the
"Note:" in the code refers to.
When 'f' is not in 'ma', 'a' will be 'nullid' and all the if/elif
conditions that check whether some one nodeid is equal to 'a' will
fail, and the else-clause will instead apply. We can make that more
explicit by creating a separate 'm' action for the case where 'a' is
'nullid'. While it does mean copying some code, perhaps it makes it a
little clearer which codepaths are possible, and which cases the
"Note:" in the code refers to. It also lets us make the debug action
messages a little more specific.
Preparing for action list split-up, making sure the final change don't have any
test changes.
The patch moves debug statements around without really changing anything.
Arguably, it temporarily makes the code worse. The only justification is that
it makes it easier to review the test changes ... and in the end the big change
will not change test output at all.
The changes to test output are due to changes in the ordering of debug output.
That is mainly because we now do the debug logging for files when we actually
process them. Files are also processed in a slightly different but still
correct order. It is now primarily ordered by action type, secondarily by
filename.
The patch introduces some redundancy. Some of it will be removed again, some of
it will in the end help code readability and efficiency. It is possible that we
later on could introduce a "process this action list and do some logging and
progress reporting and apply this function".
The "preserving X for resolve" debug statements will only have single space
indentation. It will no longer have a leading single space indented "f: msg ->
m" message. Having this message double indented would thus no longer make
sense.
The bid actions will temporarily be sorted using a custom sort key that happens
to match the sort order the simplified code will have in the end.
The ordering of actions matters. Normal file system semantics is that files
have to be removed before a directory with the same name can be created.
Before the first ordering key was to have 'r' and 'f' actions come first,
secondary key was the filename.
Because of future refactorings we want to consistently have all action types
(with a sensible priority) as separate first keys. Grouped by action type, we
sort by filename.
Not processing in strict filename order could give worse performance,
especially on spinning disks. That is however primarily an issue in the cases
where "all" actions are of the same kind and will be grouped together anyway.
Such a 'keep' action will later be the preferred (non)action when there
is multiple ancestors. It is thus very convenient to have it explicitly.
The extra actions will only be emitted in the case where the local file has
changed since the ancestor but the other hasn't. That is the symmetrical
operation to a 'get' action.
This will create more action tuples that not really serve a purpose. The number
of actions will however have the number of changed files as upper bound and it
should thus not increase the memory/cpu use significantly.
"merge.applyupdates()" sorts "actions" in removal first order, and
"workeractions" derived from it should be also sorted.
If each actions in "workeractions" are executed in serial, this
sorting ensures that merging/updating process is collision free,
because updating the file in target context is always executed after
removing the existing file which causes case-folding collision against
the former.
In the other hand, if each actions are executed in parallel, updating
on a worker process may be executed before removing on another worker
process, because "worker.partition()" partitions list of actions
regardless of type of each actions.
This patch divides "workeractions" into removing and updating, and
executes the former first.
This patch still scans "actions"/"workeractions" some times for ease
of patch review, even though large list may cost much in this way.
(total cost should be as same as before)
This also changes some tests, because dividing "workeractions" affects
progress indication.
Show messages at a point where the actions have been sorted, thus preparing for
backout of 14f4258e3526.
This makes manifestmerge more of a silent operation, just like 'copies' is.
Indent 'preserving' messages to make them subordinate to the action logging so
they fit in the new context. (The 'preserving' messages are quite redundant and
could also be removed completely.)
Preparing for backout of 14f4258e3526.
The number of prompts will for all relevant cases be significantly smaller than
the total number of files in the manifests. We can thus afford to sort the
prompts more than we can afford to sort the manifests.
The -> in debug messages is currently overloaded to mean both source to dest
and dest to source. To fix this, we add explicit labels and make the arrow
direction consistent.
Many tests didn't change back from subdirectories at the end of the tests ...
and they don't have to. The missing 'cd ..' could always be added when another
test case is added to the test file.
This change do that tests (99.5%) consistently end up in $TESTDIR where they
started, thus making it simpler to extend them or move them around.
ui.forcemerge is set before calling into merge or resolve commands, then unset
to prevent ui pollution for further operations.
ui.forcemerge takes precedence over HGMERGE, but mimics HGMERGE behavior if the
given --tool is not found by the merge-tools machinery. This makes it possible
to do: hg resolve --tool="python mymerge.py" FILE
With this approach, HGMERGE and ui.merge are not harmed by --tool
See the Hg Book on why we actually want to detect this case:
http://hgbook.red-bean.com/read/mercurial-in-daily-use.html#id364290
Before:
$ hg up deadbeef
warning: detected divergent renames of X to:
...
After:
$ hg up deadbeef
note: possible conflict - X was renamed multiple times to:
...
No functionality change.
