An alternative to using PQM

[Nicholas Allen]

Thanks a lot!

John Arbash Meinel wrote:
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> Nicholas Allen wrote:
>>> Either way would be fairly easy, I think.  I'd probably write it in
>>> Python with
>>> bzrlib personally, because I'm reasonably familiar with bzrlib and so
>>> it'd give
>>> me more flexibility, and it's easier to write unit tests for python
>>> code than
>>> shell scripts.
>>>
>>> If I didn't use bzrlib, I probably wouldn't choose a shell script, I'd
>>> write
>>> Python using the subprocess module instead :)
>> Is it easily possible to determine if conflicts occurred by looking at
>> the exit code for "bzr merge"? Likewise for other commands like push and
>> commit to see if they were successful? The only other problem I see by
>> running processes is when branches are password protected. The script
>> would have to enter the password at the right time.
>>
>> Thanks,
>>
>> Nicholas Allen
> 
> 'bzr merge' returns 0 if it is a clean merge, and 1 if there are conflicts.
> 
> So yes, you can use the return value.
> 
> For 'password protected' branches...
> 
> I'm not sure how you are thinking to set this up, but the most common
> thing would be to have everyone push to the same machine, into
> neighboring directories. Possibly into the same repository (just to
> avoid pushing the same data multiple times).
> 
> Then the ChangeIntegrator could just run over all the branches in that
> directory.
> 
> For 'bzrlib' versus 'bzr'. It could be done either way. I personally
> would probably do it using 'bzrlib', because it is a richer api. For
> example, you could do something like:
> 
> # You need a working directory to do merging inside, but the stuff you
> # pull from only needs a 'Branch'.
> target_tree = bzrlib.workingtree.WorkingTree.open(target_path)
> target_ancestry = target_tree.branch.repository.get_revision_graph(
> 	target_tree.last_revision())
> 
> for root, dirs, files in os.walk(possible_branches):
>     try:
>         a_branch = bzrlib.branch.Branch.open(root)
>     except bzrlib.errors.NotBranchError:
>         continue
>     last_revision_id = a_branch.last_revision()
>     if last_revision_id in target_ancestry:
>         continue # This branch has already been merged
> 
>     rev_info = a_branch.repository.get_revision(last_revision_id)
>     # Do the merge
>     conflicts = target_tree.merge_from_branch(a_branch)
>     # Check for conflicts
>     if len(conflicts) > 0:
>         target_tree.revert()
>         # email the user about 'conflicts'
>         continue
> 
>     # Run the test suite
>     # Mix stderr and stdout so the information is in order
>     # rather than separated, alternatively, keep it separate
>     p = subprocess.popen(['make test'], cwd=target_tree.basedir
> 			 stdout=subprocess.PIPE,
> 			 stderr=subprocess.STDOUT)
>     out, err = p.communicate()
> 
>     if p.returncode != 0:
>       # Email the user about 'failed test suite'
>       # sending them the contents of 'out'
>       target_tree.revert()
>       continue
> 
>     # v- Commit the change to the mainline, possibly preserving
>     # the committer's name, and possibly preserving the commit message
>     target_tree.commit(message=rev_info.message,
> 			committer=rev_info.committer)
>     # Email the development group about the successful merge
> 
> 
> This is much simpler than using a shell script and checking the return
> code for 'bzr missing' to see if anything needs to be merged, and 'bzr
> merge' to see if there are any conflicts.
> 
> The above little snippet is probably 90% of what you need in your
> proposed ChangeIntegrator. Depending on how much configuration you want
> to do outside of the script. And whether you want the merged commit to
> have the same message, or whether you want to put some sort of
> 'Automerged' string into it, or use a different committer id, or ....
> 
> There are a lot of ways to extend it. But that should give you the bulk
> of what you want.
> 
> John
> =:->
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