git: avoid looking-up parents for the null commit

Differential Revision: https://phab.mercurial-scm.org/D8541

hgext/git/gitlog.py

@@ -1,466 +1,469
 from __future__ import absolute_import
 
 from mercurial.i18n import _
 
 from mercurial import (
     ancestor,
     changelog as hgchangelog,
     dagop,
     encoding,
     error,
     manifest,
     node as nodemod,
     pycompat,
 )
 from mercurial.interfaces import (
     repository,
     util as interfaceutil,
 )
 from mercurial.utils import stringutil
 from . import (
     gitutil,
     index,
     manifest as gitmanifest,
 )
 
 pygit2 = gitutil.get_pygit2()
 
 
 class baselog(object):  # revlog.revlog):
     """Common implementations between changelog and manifestlog."""
 
     def __init__(self, gr, db):
         self.gitrepo = gr
         self._db = db
 
     def __len__(self):
         return int(
             self._db.execute('SELECT COUNT(*) FROM changelog').fetchone()[0]
         )
 
     def rev(self, n):
         if n == nodemod.nullid:
             return -1
         t = self._db.execute(
             'SELECT rev FROM changelog WHERE node = ?', (gitutil.togitnode(n),)
         ).fetchone()
         if t is None:
             raise error.LookupError(n, b'00changelog.i', _(b'no node %d'))
         return t[0]
 
     def node(self, r):
         if r == nodemod.nullrev:
             return nodemod.nullid
         t = self._db.execute(
             'SELECT node FROM changelog WHERE rev = ?', (r,)
         ).fetchone()
         if t is None:
             raise error.LookupError(r, b'00changelog.i', _(b'no node'))
         return nodemod.bin(t[0])
 
     def hasnode(self, n):
         t = self._db.execute(
             'SELECT node FROM changelog WHERE node = ?', (n,)
         ).fetchone()
         return t is not None
 
 
 class baselogindex(object):
     def __init__(self, log):
         self._log = log
 
     def has_node(self, n):
         return self._log.rev(n) != -1
 
     def __len__(self):
         return len(self._log)
 
     def __getitem__(self, idx):
         p1rev, p2rev = self._log.parentrevs(idx)
         # TODO: it's messy that the index leaks so far out of the
         # storage layer that we have to implement things like reading
         # this raw tuple, which exposes revlog internals.
         return (
             # Pretend offset is just the index, since we don't really care.
             idx,
             # Same with lengths
             idx,  # length
             idx,  # rawsize
             -1,  # delta base
             idx,  # linkrev TODO is this right?
             p1rev,
             p2rev,
             self._log.node(idx),
         )
 
 
 # TODO: an interface for the changelog type?
 class changelog(baselog):
     def __contains__(self, rev):
         try:
             self.node(rev)
             return True
         except error.LookupError:
             return False
 
     def __iter__(self):
         return iter(pycompat.xrange(len(self)))
 
     @property
     def filteredrevs(self):
         # TODO: we should probably add a refs/hg/ namespace for hidden
         # heads etc, but that's an idea for later.
         return set()
 
     @property
     def index(self):
         return baselogindex(self)
 
     @property
     def nodemap(self):
         r = {
             nodemod.bin(v[0]): v[1]
             for v in self._db.execute('SELECT node, rev FROM changelog')
         }
         r[nodemod.nullid] = nodemod.nullrev
         return r
 
     def tip(self):
         t = self._db.execute(
             'SELECT node FROM changelog ORDER BY rev DESC LIMIT 1'
         ).fetchone()
         if t:
             return nodemod.bin(t[0])
         return nodemod.nullid
 
     def revs(self, start=0, stop=None):
         if stop is None:
             stop = self.tip()
         t = self._db.execute(
             'SELECT rev FROM changelog '
             'WHERE rev >= ? AND rev <= ? '
             'ORDER BY REV ASC',
             (start, stop),
         )
         return (int(r[0]) for r in t)
 
     def _partialmatch(self, id):
         if nodemod.wdirhex.startswith(id):
             raise error.WdirUnsupported
         candidates = [
             nodemod.bin(x[0])
             for x in self._db.execute(
                 'SELECT node FROM changelog WHERE node LIKE ?', (id + b'%',)
             )
         ]
         if nodemod.nullhex.startswith(id):
             candidates.append(nodemod.nullid)
         if len(candidates) > 1:
             raise error.AmbiguousPrefixLookupError(
                 id, b'00changelog.i', _(b'ambiguous identifier')
             )
         if candidates:
             return candidates[0]
         return None
 
     def flags(self, rev):
         return 0
 
     def shortest(self, node, minlength=1):
         nodehex = nodemod.hex(node)
         for attempt in pycompat.xrange(minlength, len(nodehex) + 1):
             candidate = nodehex[:attempt]
             matches = int(
                 self._db.execute(
                     'SELECT COUNT(*) FROM changelog WHERE node LIKE ?',
                     (pycompat.sysstr(candidate + b'%'),),
                 ).fetchone()[0]
             )
             if matches == 1:
                 return candidate
         return nodehex
 
     def headrevs(self, revs=None):
         realheads = [
             int(x[0])
             for x in self._db.execute(
                 'SELECT rev FROM changelog '
                 'INNER JOIN heads ON changelog.node = heads.node'
             )
         ]
         if revs:
             return sorted([r for r in revs if r in realheads])
         return sorted(realheads)
 
     def changelogrevision(self, nodeorrev):
         # Ensure we have a node id
         if isinstance(nodeorrev, int):
             n = self.node(nodeorrev)
         else:
             n = nodeorrev
         # handle looking up nullid
         if n == nodemod.nullid:
             return hgchangelog._changelogrevision(extra={})
         hn = gitutil.togitnode(n)
         # We've got a real commit!
         files = [
             r[0]
             for r in self._db.execute(
                 'SELECT filename FROM changedfiles '
                 'WHERE node = ? and filenode != ?',
                 (hn, gitutil.nullgit),
             )
         ]
         filesremoved = [
             r[0]
             for r in self._db.execute(
                 'SELECT filename FROM changedfiles '
                 'WHERE node = ? and filenode = ?',
                 (hn, nodemod.nullhex),
             )
         ]
         c = self.gitrepo[hn]
         return hgchangelog._changelogrevision(
             manifest=n,  # pretend manifest the same as the commit node
             user=b'%s <%s>'
             % (c.author.name.encode('utf8'), c.author.email.encode('utf8')),
             date=(c.author.time, -c.author.offset * 60),
             files=files,
             # TODO filesadded in the index
             filesremoved=filesremoved,
             description=c.message.encode('utf8'),
             # TODO do we want to handle extra? how?
             extra={b'branch': b'default'},
         )
 
     def ancestors(self, revs, stoprev=0, inclusive=False):
         revs = list(revs)
         tip = self.rev(self.tip())
         for r in revs:
             if r > tip:
                 raise IndexError(b'Invalid rev %r' % r)
         return ancestor.lazyancestors(
             self.parentrevs, revs, stoprev=stoprev, inclusive=inclusive
         )
 
     # Cleanup opportunity: this is *identical* to the revlog.py version
     def descendants(self, revs):
         return dagop.descendantrevs(revs, self.revs, self.parentrevs)
 
     def reachableroots(self, minroot, heads, roots, includepath=False):
         return dagop._reachablerootspure(
             self.parentrevs, minroot, roots, heads, includepath
         )
 
     # Cleanup opportunity: this is *identical* to the revlog.py version
     def isancestor(self, a, b):
         a, b = self.rev(a), self.rev(b)
         return self.isancestorrev(a, b)
 
     # Cleanup opportunity: this is *identical* to the revlog.py version
     def isancestorrev(self, a, b):
         if a == nodemod.nullrev:
             return True
         elif a == b:
             return True
         elif a > b:
             return False
         return bool(self.reachableroots(a, [b], [a], includepath=False))
 
     def parentrevs(self, rev):
         n = self.node(rev)
         hn = gitutil.togitnode(n)
-        c = self.gitrepo[hn]
+        if hn != gitutil.nullgit:
+            c = self.gitrepo[hn]
+        else:
+            return nodemod.nullrev, nodemod.nullrev
         p1 = p2 = nodemod.nullrev
         if c.parents:
             p1 = self.rev(c.parents[0].id.raw)
             if len(c.parents) > 2:
                 raise error.Abort(b'TODO octopus merge handling')
             if len(c.parents) == 2:
                 p2 = self.rev(c.parents[1].id.raw)
         return p1, p2
 
     # Private method is used at least by the tags code.
     _uncheckedparentrevs = parentrevs
 
     def commonancestorsheads(self, a, b):
         # TODO the revlog verson of this has a C path, so we probably
         # need to optimize this...
         a, b = self.rev(a), self.rev(b)
         return [
             self.node(n)
             for n in ancestor.commonancestorsheads(self.parentrevs, a, b)
         ]
 
     def branchinfo(self, rev):
         """Git doesn't do named branches, so just put everything on default."""
         return b'default', False
 
     def delayupdate(self, tr):
         # TODO: I think we can elide this because we're just dropping
         # an object in the git repo?
         pass
 
     def add(
         self,
         manifest,
         files,
         desc,
         transaction,
         p1,
         p2,
         user,
         date=None,
         extra=None,
         p1copies=None,
         p2copies=None,
         filesadded=None,
         filesremoved=None,
     ):
         parents = []
         hp1, hp2 = gitutil.togitnode(p1), gitutil.togitnode(p2)
         if p1 != nodemod.nullid:
             parents.append(hp1)
         if p2 and p2 != nodemod.nullid:
             parents.append(hp2)
         assert date is not None
         timestamp, tz = date
         sig = pygit2.Signature(
             encoding.unifromlocal(stringutil.person(user)),
             encoding.unifromlocal(stringutil.email(user)),
             timestamp,
             -(tz // 60),
         )
         oid = self.gitrepo.create_commit(
             None, sig, sig, desc, gitutil.togitnode(manifest), parents
         )
         # Set up an internal reference to force the commit into the
         # changelog. Hypothetically, we could even use this refs/hg/
         # namespace to allow for anonymous heads on git repos, which
         # would be neat.
         self.gitrepo.references.create(
             'refs/hg/internal/latest-commit', oid, force=True
         )
         # Reindex now to pick up changes. We omit the progress
         # callback because this will be very quick.
         index._index_repo(self.gitrepo, self._db)
         return oid.raw
 
 
 class manifestlog(baselog):
     def __getitem__(self, node):
         return self.get(b'', node)
 
     def get(self, relpath, node):
         if node == nodemod.nullid:
             # TODO: this should almost certainly be a memgittreemanifestctx
             return manifest.memtreemanifestctx(self, relpath)
         commit = self.gitrepo[gitutil.togitnode(node)]
         t = commit.tree
         if relpath:
             parts = relpath.split(b'/')
             for p in parts:
                 te = t[p]
                 t = self.gitrepo[te.id]
         return gitmanifest.gittreemanifestctx(self.gitrepo, t)
 
 
 @interfaceutil.implementer(repository.ifilestorage)
 class filelog(baselog):
     def __init__(self, gr, db, path):
         super(filelog, self).__init__(gr, db)
         assert isinstance(path, bytes)
         self.path = path
 
     def read(self, node):
         if node == nodemod.nullid:
             return b''
         return self.gitrepo[gitutil.togitnode(node)].data
 
     def lookup(self, node):
         if len(node) not in (20, 40):
             node = int(node)
         if isinstance(node, int):
             assert False, b'todo revnums for nodes'
         if len(node) == 40:
             node = nodemod.bin(node)
         hnode = gitutil.togitnode(node)
         if hnode in self.gitrepo:
             return node
         raise error.LookupError(self.path, node, _(b'no match found'))
 
     def cmp(self, node, text):
         """Returns True if text is different than content at `node`."""
         return self.read(node) != text
 
     def add(self, text, meta, transaction, link, p1=None, p2=None):
         assert not meta  # Should we even try to handle this?
         return self.gitrepo.create_blob(text).raw
 
     def __iter__(self):
         for clrev in self._db.execute(
             '''
 SELECT rev FROM changelog
 INNER JOIN changedfiles ON changelog.node = changedfiles.node
 WHERE changedfiles.filename = ? AND changedfiles.filenode != ?
         ''',
             (pycompat.fsdecode(self.path), gitutil.nullgit),
         ):
             yield clrev[0]
 
     def linkrev(self, fr):
         return fr
 
     def rev(self, node):
         row = self._db.execute(
             '''
 SELECT rev FROM changelog
 INNER JOIN changedfiles ON changelog.node = changedfiles.node
 WHERE changedfiles.filename = ? AND changedfiles.filenode = ?''',
             (pycompat.fsdecode(self.path), gitutil.togitnode(node)),
         ).fetchone()
         if row is None:
             raise error.LookupError(self.path, node, _(b'no such node'))
         return int(row[0])
 
     def node(self, rev):
         maybe = self._db.execute(
             '''SELECT filenode FROM changedfiles
 INNER JOIN changelog ON changelog.node = changedfiles.node
 WHERE changelog.rev = ? AND filename = ?
 ''',
             (rev, pycompat.fsdecode(self.path)),
         ).fetchone()
         if maybe is None:
             raise IndexError('gitlog %r out of range %d' % (self.path, rev))
         return nodemod.bin(maybe[0])
 
     def parents(self, node):
         gn = gitutil.togitnode(node)
         gp = pycompat.fsdecode(self.path)
         ps = []
         for p in self._db.execute(
             '''SELECT p1filenode, p2filenode FROM changedfiles
 WHERE filenode = ? AND filename = ?
 ''',
             (gn, gp),
         ).fetchone():
             if p is None:
                 commit = self._db.execute(
                     "SELECT node FROM changedfiles "
                     "WHERE filenode = ? AND filename = ?",
                     (gn, gp),
                 ).fetchone()[0]
                 # This filelog is missing some data. Build the
                 # filelog, then recurse (which will always find data).
                 if pycompat.ispy3:
                     commit = commit.decode('ascii')
                 index.fill_in_filelog(self.gitrepo, self._db, commit, gp, gn)
                 return self.parents(node)
             else:
                 ps.append(nodemod.bin(p))
         return ps
 
     def renamed(self, node):
         # TODO: renames/copies
         return False