Mercurial > hg
diff mercurial/utils/storageutil.py @ 40004:fa3dc85a747e
storageutil: extract functionality for resolving strip revisions
I found myself having to copy this method as part of implementing a new
storage backend. With a little tweaking, we can extract it to a
standalone function so it can be reused easily.
We'll likely want to implement a better method for removing revisions
on the storage interface someday. But until then, let's use what we
have.
Differential Revision: https://phab.mercurial-scm.org/D4799
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Fri, 28 Sep 2018 11:29:05 -0700 |
parents | ad8389ecd3f5 |
children | 1d97a332c6d9 |
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--- a/mercurial/utils/storageutil.py Fri Sep 28 11:16:44 2018 -0700 +++ b/mercurial/utils/storageutil.py Fri Sep 28 11:29:05 2018 -0700 @@ -14,6 +14,7 @@ from ..node import ( bin, nullid, + nullrev, ) from .. import ( error, @@ -155,3 +156,54 @@ pass raise error.LookupError(fileid, identifier, _('no match found')) + +def resolvestripinfo(minlinkrev, tiprev, headrevs, linkrevfn, parentrevsfn): + """Resolve information needed to strip revisions. + + Finds the minimum revision number that must be stripped in order to + strip ``minlinkrev``. + + Returns a 2-tuple of the minimum revision number to do that and a set + of all revision numbers that have linkrevs that would be broken + by that strip. + + ``tiprev`` is the current tip-most revision. It is ``len(store) - 1``. + ``headrevs`` is an iterable of head revisions. + ``linkrevfn`` is a callable that receives a revision and returns a linked + revision. + ``parentrevsfn`` is a callable that receives a revision number and returns + an iterable of its parent revision numbers. + """ + brokenrevs = set() + strippoint = tiprev + 1 + + heads = {} + futurelargelinkrevs = set() + for head in headrevs: + headlinkrev = linkrevfn(head) + heads[head] = headlinkrev + if headlinkrev >= minlinkrev: + futurelargelinkrevs.add(headlinkrev) + + # This algorithm involves walking down the rev graph, starting at the + # heads. Since the revs are topologically sorted according to linkrev, + # once all head linkrevs are below the minlink, we know there are + # no more revs that could have a linkrev greater than minlink. + # So we can stop walking. + while futurelargelinkrevs: + strippoint -= 1 + linkrev = heads.pop(strippoint) + + if linkrev < minlinkrev: + brokenrevs.add(strippoint) + else: + futurelargelinkrevs.remove(linkrev) + + for p in parentrevsfn(strippoint): + if p != nullrev: + plinkrev = linkrevfn(p) + heads[p] = plinkrev + if plinkrev >= minlinkrev: + futurelargelinkrevs.add(plinkrev) + + return strippoint, brokenrevs