Re: Tracking "branch heads"

On Mon, Dec 14, 2009 at 11:48 AM, Michael Haggerty <[email protected]> wrote:
>> So it looks like the clever thing to do is modify CreateRevsPass to
>> build a dictionary mapping branch name to highest rev number on that
>> branch, then ensure that dictionary is persisted somehow and available
>> to OutputPass/OutputOption.
>
> Sounds reasonable.
>
> By the way, another elegant way to solve the problem would be to add one
> "CVSBranchTip" CVSItem into the dependency graph for each branch.  Such
> an item would depend on the last commit on the branch in each file.  The
> normal dependency-sorting code would make the corresponding "commits"
> occur after the last commit on the branch, and the OutputOptions would
> see them come through like any other commit.

Hmmm.  Interesting idea, but that's farther back in the pipeline than
I wanted to go.  I think I've got it working in CreateRevsPass, so I'm
gonna stick with that.

>> 1) any interest in such a patch being accepted upstream?  I'm pretty
>> sure it will be orthogonal to my "add cvs2hg" patch series, so I could
>> send it in as soon as it works, if you're interested.
>
> I don't see a problem with it.

Cool.  OK, here is a preliminary draft.  This passes its test, but I
have not yet used it in production.  I'll see how the design actually
works within the next 24 hours.  For your amusement...

"""
# HG changeset patch
# User Greg Ward <[email protected]>
# Date 1260821833 18000
# Node ID 1763b1aba3259d59ed84141f046f73a35331a7e0
# Parent  64442bf496d83c4a1883bddc51a387493edeabd1
Record the head of each branch as we generate Subversion revisions.
This should make life easier for DVCS conversions, where it's often
desirable to do special things with branch heads (close them, merge
them, etc.)

* config.py: add SVN_BRANCH_HEADS file (a pickled dictionary)
* passes.py: modify CreateRevsPass to record and write branch heads
* run-tests.py: add a test

diff --git a/cvs2svn_lib/config.py b/cvs2svn_lib/config.py
--- a/cvs2svn_lib/config.py
+++ b/cvs2svn_lib/config.py
@@ -159,6 +159,12 @@
 # pickled SVNCommit instances.
 CVS_REVS_TO_SVN_REVNUMS = 'cvs-revs-to-svn-revnums.dat'

+# Pickled dictionary mapping LOD as (id, name) tuple to branch head
+# (highest svn revision number on that branch).  Only Trunk and Branch LODs
+# will be recorded here.  The LOD name is only recorded for testing
+# purposes; if you use this dict, you really should use the LOD id.
+SVN_BRANCH_HEADS = 'svn-branch-heads.pck'
+
 # This database maps Subversion revision numbers to pickled SVNCommit
 # instances.
 SVN_COMMITS_INDEX_TABLE = 'svn-commits-index.dat'
diff --git a/cvs2svn_lib/passes.py b/cvs2svn_lib/passes.py
--- a/cvs2svn_lib/passes.py
+++ b/cvs2svn_lib/passes.py
@@ -1541,6 +1541,7 @@
     self._register_temp_file(config.SVN_COMMITS_STORE)
     self._register_temp_file(config.CVS_REVS_TO_SVN_REVNUMS)
     self._register_temp_file(config.SYMBOL_OPENINGS_CLOSINGS)
+    self._register_temp_file(config.SVN_BRANCH_HEADS)
     self._register_temp_file_needed(config.PROJECTS)
     self._register_temp_file_needed(config.CVS_FILES_DB)
     self._register_temp_file_needed(config.CVS_ITEMS_SORTED_STORE)
@@ -1585,6 +1586,23 @@
       for cvs_rev in svn_commit.cvs_revs:
         Log().verbose(' %s %s' % (cvs_rev.cvs_path, cvs_rev.rev,))

+  def update_branch_heads(self, branch_heads, svn_commit):
+    for cvs_rev in svn_commit.get_cvs_items():
+      if isinstance(cvs_rev, CVSRevision):  # ordinary commit
+        lod = cvs_rev.lod
+        id = lod.id
+        if isinstance(lod, Trunk):
+          name = str(lod)
+        elif isinstance(lod, Branch):
+          name = lod.name
+        else:
+          continue
+      else:
+        continue
+
+      branch_heads[(id, name)] = svn_commit.revnum
+
+
   def run(self, run_options, stats_keeper):
     Log().quiet("Mapping CVS revisions to Subversion commits...")

@@ -1599,6 +1617,7 @@
         DB_OPEN_READ)

     Ctx()._symbolings_logger = SymbolingsLogger()
+    branch_heads = {}                   # map (LOD id, name) to head revnum

     persistence_manager = PersistenceManager(DB_OPEN_NEW)

@@ -1606,6 +1625,12 @@
     for svn_commit in self.get_svn_commits(creator):
       self.log_svn_commit(svn_commit)
       persistence_manager.put_svn_commit(svn_commit)
+      self.update_branch_heads(branch_heads, svn_commit)
+
+    # Write the branch_heads dict.
+    file = open(artifact_manager.get_temp_file(config.SVN_BRANCH_HEADS), 'wb')
+    cPickle.dump(branch_heads, file, -1)
+    file.close()

     stats_keeper.set_svn_rev_count(creator.revnum_generator.get_last_id())
     del creator
@@ -1712,6 +1737,7 @@
     self._register_temp_file_needed(config.SVN_COMMITS_INDEX_TABLE)
     self._register_temp_file_needed(config.SVN_COMMITS_STORE)
     self._register_temp_file_needed(config.CVS_REVS_TO_SVN_REVNUMS)
+    self._register_temp_file_needed(config.SVN_BRANCH_HEADS)
     Ctx().output_option.register_artifacts(self)

   def run(self, run_options, stats_keeper):
diff --git a/run-tests.py b/run-tests.py
--- a/run-tests.py
+++ b/run-tests.py
@@ -4584,6 +4584,33 @@
         ('trunk/proj/sub1/default', [None]),
         ])

+@Cvs2SvnTestFunction
+def branch_heads():
+  "record head of each branch"
+  import cPickle
+  from cvs2svn_lib.symbol import Trunk, Branch
+
+  conv = ensure_conversion('main', args=['--skip-cleanup',])
+  file = open('cvs2svn-tmp/svn-branch-heads.pck', 'rb')
+  branch_heads = cPickle.load(file)
+  file.close()
+
+  expect = {
+    # these are easy and obvious, since they all have CVS commits
+    "Trunk":    33,
+    "B_SPLIT":  32,
+    "B_MIXED":  24,
+
+    }
+
+  actual = {}
+  for ((id, name), revnum) in branch_heads.items():
+    actual[name] = revnum
+
+  if expect != actual:
+    raise Failure("branch heads: expected:\n%s\nbut got:\n%s"
+                  % (expect, actual))
+

 ########################################################################
 # Run the tests
@@ -4802,6 +4829,7 @@
     collision_with_unlabeled_branch_name,
     many_deletes,
     cvs_description,
+    branch_heads,
     ]

 if __name__ == '__main__':
"""

Of note: I do *not* use branch creation events to update branch_heads.
 I have a patch that adds that, but:

  * it ensures that CVS branches that never actually had any commits
are present in
    branch_heads... but it's not clear if that is a good thing or a bad thing
  * it complicates matters by recording "split" CVS branches under two distinct
    LOD IDs

Think about it.  I'll send the second patch if you want, but it feels
wrong to me.

Greg

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