help: add internals.extensions topic
I think it's better to include the API overview in core as we now have the
internals section in our help system.
Retrieved from the wiki, and formatted as reST. Several wiki links are
removed since they are invalid in the help. The sections about example
extension are removed at all as they seemed too verbose.
https://www.mercurial-scm.org/wiki/WritingExtensions
# simplestorerepo.py - Extension that swaps in alternate repository storage.
#
# Copyright 2018 Gregory Szorc <gregory.szorc@gmail.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
# To use this with the test suite:
#
# $ HGREPOFEATURES="simplestore" ./run-tests.py \
# --extra-config-opt extensions.simplestore=`pwd`/simplestorerepo.py
from __future__ import absolute_import
import stat
from mercurial.i18n import _
from mercurial.node import (
bin,
hex,
nullid,
nullrev,
)
from mercurial.thirdparty import (
attr,
cbor,
)
from mercurial import (
ancestor,
bundlerepo,
error,
extensions,
localrepo,
mdiff,
pycompat,
repository,
revlog,
store,
verify,
)
from mercurial.utils import (
interfaceutil,
storageutil,
)
# Note for extension authors: ONLY specify testedwith = 'ships-with-hg-core' for
# extensions which SHIP WITH MERCURIAL. Non-mainline extensions should
# be specifying the version(s) of Mercurial they are tested with, or
# leave the attribute unspecified.
testedwith = 'ships-with-hg-core'
REQUIREMENT = 'testonly-simplestore'
def validatenode(node):
if isinstance(node, int):
raise ValueError('expected node; got int')
if len(node) != 20:
raise ValueError('expected 20 byte node')
def validaterev(rev):
if not isinstance(rev, int):
raise ValueError('expected int')
class simplestoreerror(error.StorageError):
pass
@interfaceutil.implementer(repository.irevisiondelta)
@attr.s(slots=True, frozen=True)
class simplestorerevisiondelta(object):
node = attr.ib()
p1node = attr.ib()
p2node = attr.ib()
basenode = attr.ib()
linknode = attr.ib()
flags = attr.ib()
baserevisionsize = attr.ib()
revision = attr.ib()
delta = attr.ib()
@interfaceutil.implementer(repository.ifilestorage)
class filestorage(object):
"""Implements storage for a tracked path.
Data is stored in the VFS in a directory corresponding to the tracked
path.
Index data is stored in an ``index`` file using CBOR.
Fulltext data is stored in files having names of the node.
"""
def __init__(self, svfs, path):
self._svfs = svfs
self._path = path
self._storepath = b'/'.join([b'data', path])
self._indexpath = b'/'.join([self._storepath, b'index'])
indexdata = self._svfs.tryread(self._indexpath)
if indexdata:
indexdata = cbor.loads(indexdata)
self._indexdata = indexdata or []
self._indexbynode = {}
self._indexbyrev = {}
self._index = []
self._refreshindex()
def _refreshindex(self):
self._indexbynode.clear()
self._indexbyrev.clear()
self._index = []
for i, entry in enumerate(self._indexdata):
self._indexbynode[entry[b'node']] = entry
self._indexbyrev[i] = entry
self._indexbynode[nullid] = {
b'node': nullid,
b'p1': nullid,
b'p2': nullid,
b'linkrev': nullrev,
b'flags': 0,
}
self._indexbyrev[nullrev] = {
b'node': nullid,
b'p1': nullid,
b'p2': nullid,
b'linkrev': nullrev,
b'flags': 0,
}
for i, entry in enumerate(self._indexdata):
p1rev, p2rev = self.parentrevs(self.rev(entry[b'node']))
# start, length, rawsize, chainbase, linkrev, p1, p2, node
self._index.append((0, 0, 0, -1, entry[b'linkrev'], p1rev, p2rev,
entry[b'node']))
self._index.append((0, 0, 0, -1, -1, -1, -1, nullid))
def __len__(self):
return len(self._indexdata)
def __iter__(self):
return iter(range(len(self)))
def revs(self, start=0, stop=None):
step = 1
if stop is not None:
if start > stop:
step = -1
stop += step
else:
stop = len(self)
return range(start, stop, step)
def parents(self, node):
validatenode(node)
if node not in self._indexbynode:
raise KeyError('unknown node')
entry = self._indexbynode[node]
return entry[b'p1'], entry[b'p2']
def parentrevs(self, rev):
p1, p2 = self.parents(self._indexbyrev[rev][b'node'])
return self.rev(p1), self.rev(p2)
def rev(self, node):
validatenode(node)
try:
self._indexbynode[node]
except KeyError:
raise error.LookupError(node, self._indexpath, _('no node'))
for rev, entry in self._indexbyrev.items():
if entry[b'node'] == node:
return rev
raise error.ProgrammingError('this should not occur')
def node(self, rev):
validaterev(rev)
return self._indexbyrev[rev][b'node']
def lookup(self, node):
if isinstance(node, int):
return self.node(node)
if len(node) == 20:
self.rev(node)
return node
try:
rev = int(node)
if '%d' % rev != node:
raise ValueError
if rev < 0:
rev = len(self) + rev
if rev < 0 or rev >= len(self):
raise ValueError
return self.node(rev)
except (ValueError, OverflowError):
pass
if len(node) == 40:
try:
rawnode = bin(node)
self.rev(rawnode)
return rawnode
except TypeError:
pass
raise error.LookupError(node, self._path, _('invalid lookup input'))
def linkrev(self, rev):
validaterev(rev)
return self._indexbyrev[rev][b'linkrev']
def _flags(self, rev):
validaterev(rev)
return self._indexbyrev[rev][b'flags']
def _candelta(self, baserev, rev):
validaterev(baserev)
validaterev(rev)
if ((self._flags(baserev) & revlog.REVIDX_RAWTEXT_CHANGING_FLAGS)
or (self._flags(rev) & revlog.REVIDX_RAWTEXT_CHANGING_FLAGS)):
return False
return True
def _processflags(self, text, flags, operation, raw=False):
if flags == 0:
return text, True
if flags & ~revlog.REVIDX_KNOWN_FLAGS:
raise simplestoreerror(_("incompatible revision flag '%#x'") %
(flags & ~revlog.REVIDX_KNOWN_FLAGS))
validatehash = True
# Depending on the operation (read or write), the order might be
# reversed due to non-commutative transforms.
orderedflags = revlog.REVIDX_FLAGS_ORDER
if operation == 'write':
orderedflags = reversed(orderedflags)
for flag in orderedflags:
# If a flagprocessor has been registered for a known flag, apply the
# related operation transform and update result tuple.
if flag & flags:
vhash = True
if flag not in revlog._flagprocessors:
message = _("missing processor for flag '%#x'") % (flag)
raise simplestoreerror(message)
processor = revlog._flagprocessors[flag]
if processor is not None:
readtransform, writetransform, rawtransform = processor
if raw:
vhash = rawtransform(self, text)
elif operation == 'read':
text, vhash = readtransform(self, text)
else: # write operation
text, vhash = writetransform(self, text)
validatehash = validatehash and vhash
return text, validatehash
def checkhash(self, text, node, p1=None, p2=None, rev=None):
if p1 is None and p2 is None:
p1, p2 = self.parents(node)
if node != storageutil.hashrevisionsha1(text, p1, p2):
raise simplestoreerror(_("integrity check failed on %s") %
self._path)
def revision(self, node, raw=False):
validatenode(node)
if node == nullid:
return b''
rev = self.rev(node)
flags = self._flags(rev)
path = b'/'.join([self._storepath, hex(node)])
rawtext = self._svfs.read(path)
text, validatehash = self._processflags(rawtext, flags, 'read', raw=raw)
if validatehash:
self.checkhash(text, node, rev=rev)
return text
def read(self, node):
validatenode(node)
revision = self.revision(node)
if not revision.startswith(b'\1\n'):
return revision
start = revision.index(b'\1\n', 2)
return revision[start + 2:]
def renamed(self, node):
validatenode(node)
if self.parents(node)[0] != nullid:
return False
fulltext = self.revision(node)
m = storageutil.parsemeta(fulltext)[0]
if m and 'copy' in m:
return m['copy'], bin(m['copyrev'])
return False
def cmp(self, node, text):
validatenode(node)
t = text
if text.startswith(b'\1\n'):
t = b'\1\n\1\n' + text
p1, p2 = self.parents(node)
if storageutil.hashrevisionsha1(t, p1, p2) == node:
return False
if self.iscensored(self.rev(node)):
return text != b''
if self.renamed(node):
t2 = self.read(node)
return t2 != text
return True
def size(self, rev):
validaterev(rev)
node = self._indexbyrev[rev][b'node']
if self.renamed(node):
return len(self.read(node))
if self.iscensored(rev):
return 0
return len(self.revision(node))
def iscensored(self, rev):
validaterev(rev)
return self._flags(rev) & repository.REVISION_FLAG_CENSORED
def commonancestorsheads(self, a, b):
validatenode(a)
validatenode(b)
a = self.rev(a)
b = self.rev(b)
ancestors = ancestor.commonancestorsheads(self.parentrevs, a, b)
return pycompat.maplist(self.node, ancestors)
def descendants(self, revs):
# This is a copy of revlog.descendants()
first = min(revs)
if first == nullrev:
for i in self:
yield i
return
seen = set(revs)
for i in self.revs(start=first + 1):
for x in self.parentrevs(i):
if x != nullrev and x in seen:
seen.add(i)
yield i
break
# Required by verify.
def files(self):
entries = self._svfs.listdir(self._storepath)
# Strip out undo.backup.* files created as part of transaction
# recording.
entries = [f for f in entries if not f.startswith('undo.backup.')]
return [b'/'.join((self._storepath, f)) for f in entries]
def add(self, text, meta, transaction, linkrev, p1, p2):
if meta or text.startswith(b'\1\n'):
text = storageutil.packmeta(meta, text)
return self.addrevision(text, transaction, linkrev, p1, p2)
def addrevision(self, text, transaction, linkrev, p1, p2, node=None,
flags=revlog.REVIDX_DEFAULT_FLAGS, cachedelta=None):
validatenode(p1)
validatenode(p2)
if flags:
node = node or storageutil.hashrevisionsha1(text, p1, p2)
rawtext, validatehash = self._processflags(text, flags, 'write')
node = node or storageutil.hashrevisionsha1(text, p1, p2)
if node in self._indexbynode:
return node
if validatehash:
self.checkhash(rawtext, node, p1=p1, p2=p2)
return self._addrawrevision(node, rawtext, transaction, linkrev, p1, p2,
flags)
def _addrawrevision(self, node, rawtext, transaction, link, p1, p2, flags):
transaction.addbackup(self._indexpath)
path = b'/'.join([self._storepath, hex(node)])
self._svfs.write(path, rawtext)
self._indexdata.append({
b'node': node,
b'p1': p1,
b'p2': p2,
b'linkrev': link,
b'flags': flags,
})
self._reflectindexupdate()
return node
def _reflectindexupdate(self):
self._refreshindex()
self._svfs.write(self._indexpath, cbor.dumps(self._indexdata))
def addgroup(self, deltas, linkmapper, transaction, addrevisioncb=None,
maybemissingparents=False):
if maybemissingparents:
raise error.Abort(_('simple store does not support missing parents '
'write mode'))
nodes = []
transaction.addbackup(self._indexpath)
for node, p1, p2, linknode, deltabase, delta, flags in deltas:
linkrev = linkmapper(linknode)
flags = flags or revlog.REVIDX_DEFAULT_FLAGS
nodes.append(node)
if node in self._indexbynode:
continue
# Need to resolve the fulltext from the delta base.
if deltabase == nullid:
text = mdiff.patch(b'', delta)
else:
text = mdiff.patch(self.revision(deltabase), delta)
self._addrawrevision(node, text, transaction, linkrev, p1, p2,
flags)
if addrevisioncb:
addrevisioncb(self, node)
return nodes
def heads(self, start=None, stop=None):
# This is copied from revlog.py.
if start is None and stop is None:
if not len(self):
return [nullid]
return [self.node(r) for r in self.headrevs()]
if start is None:
start = nullid
if stop is None:
stop = []
stoprevs = set([self.rev(n) for n in stop])
startrev = self.rev(start)
reachable = {startrev}
heads = {startrev}
parentrevs = self.parentrevs
for r in self.revs(start=startrev + 1):
for p in parentrevs(r):
if p in reachable:
if r not in stoprevs:
reachable.add(r)
heads.add(r)
if p in heads and p not in stoprevs:
heads.remove(p)
return [self.node(r) for r in heads]
def children(self, node):
validatenode(node)
# This is a copy of revlog.children().
c = []
p = self.rev(node)
for r in self.revs(start=p + 1):
prevs = [pr for pr in self.parentrevs(r) if pr != nullrev]
if prevs:
for pr in prevs:
if pr == p:
c.append(self.node(r))
elif p == nullrev:
c.append(self.node(r))
return c
def getstrippoint(self, minlink):
# This is largely a copy of revlog.getstrippoint().
brokenrevs = set()
strippoint = len(self)
heads = {}
futurelargelinkrevs = set()
for head in self.heads():
headlinkrev = self.linkrev(self.rev(head))
heads[head] = headlinkrev
if headlinkrev >= minlink:
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 < minlink:
brokenrevs.add(strippoint)
else:
futurelargelinkrevs.remove(linkrev)
for p in self.parentrevs(strippoint):
if p != nullrev:
plinkrev = self.linkrev(p)
heads[p] = plinkrev
if plinkrev >= minlink:
futurelargelinkrevs.add(plinkrev)
return strippoint, brokenrevs
def strip(self, minlink, transaction):
if not len(self):
return
rev, _ignored = self.getstrippoint(minlink)
if rev == len(self):
return
# Purge index data starting at the requested revision.
self._indexdata[rev:] = []
self._reflectindexupdate()
def issimplestorefile(f, kind, st):
if kind != stat.S_IFREG:
return False
if store.isrevlog(f, kind, st):
return False
# Ignore transaction undo files.
if f.startswith('undo.'):
return False
# Otherwise assume it belongs to the simple store.
return True
class simplestore(store.encodedstore):
def datafiles(self):
for x in super(simplestore, self).datafiles():
yield x
# Supplement with non-revlog files.
extrafiles = self._walk('data', True, filefilter=issimplestorefile)
for unencoded, encoded, size in extrafiles:
try:
unencoded = store.decodefilename(unencoded)
except KeyError:
unencoded = None
yield unencoded, encoded, size
def reposetup(ui, repo):
if not repo.local():
return
if isinstance(repo, bundlerepo.bundlerepository):
raise error.Abort(_('cannot use simple store with bundlerepo'))
class simplestorerepo(repo.__class__):
def file(self, f):
return filestorage(self.svfs, f)
repo.__class__ = simplestorerepo
def featuresetup(ui, supported):
supported.add(REQUIREMENT)
def newreporequirements(orig, ui):
"""Modifies default requirements for new repos to use the simple store."""
requirements = orig(ui)
# These requirements are only used to affect creation of the store
# object. We have our own store. So we can remove them.
# TODO do this once we feel like taking the test hit.
#if 'fncache' in requirements:
# requirements.remove('fncache')
#if 'dotencode' in requirements:
# requirements.remove('dotencode')
requirements.add(REQUIREMENT)
return requirements
def makestore(orig, requirements, path, vfstype):
if REQUIREMENT not in requirements:
return orig(requirements, path, vfstype)
return simplestore(path, vfstype)
def verifierinit(orig, self, *args, **kwargs):
orig(self, *args, **kwargs)
# We don't care that files in the store don't align with what is
# advertised. So suppress these warnings.
self.warnorphanstorefiles = False
def extsetup(ui):
localrepo.featuresetupfuncs.add(featuresetup)
extensions.wrapfunction(localrepo, 'newreporequirements',
newreporequirements)
extensions.wrapfunction(store, 'store', makestore)
extensions.wrapfunction(verify.verifier, '__init__', verifierinit)