branchmap: add some clarifications and clean up flow
- Remove indentation where it is not needed.
- Swap the subset test branches to follow along logically and put the 'empty'
case last.
Differential Revision: https://phab.mercurial-scm.org/D5637
# branchmap.py - logic to computes, maintain and stores branchmap for local repo
#
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
from __future__ import absolute_import
import struct
from .node import (
bin,
hex,
nullid,
nullrev,
)
from . import (
encoding,
error,
pycompat,
scmutil,
util,
)
from .utils import (
stringutil,
)
calcsize = struct.calcsize
pack_into = struct.pack_into
unpack_from = struct.unpack_from
### Nearest subset relation
# Nearest subset of filter X is a filter Y so that:
# * Y is included in X,
# * X - Y is as small as possible.
# This create and ordering used for branchmap purpose.
# the ordering may be partial
subsettable = {None: 'visible',
'visible-hidden': 'visible',
'visible': 'served',
'served': 'immutable',
'immutable': 'base'}
def updatecache(repo):
"""Update the cache for the given filtered view on a repository"""
# This can trigger updates for the caches for subsets of the filtered
# view, e.g. when there is no cache for this filtered view or the cache
# is stale.
cl = repo.changelog
filtername = repo.filtername
bcache = repo._branchcaches.get(filtername)
if bcache is None or not bcache.validfor(repo):
# cache object missing or cache object stale? Read from disk
bcache = branchcache.fromfile(repo)
revs = []
if bcache is None:
# no (fresh) cache available anymore, perhaps we can re-use
# the cache for a subset, then extend that to add info on missing
# revisions.
subsetname = subsettable.get(filtername)
if subsetname is not None:
subset = repo.filtered(subsetname)
bcache = subset.branchmap().copy()
extrarevs = subset.changelog.filteredrevs - cl.filteredrevs
revs.extend(r for r in extrarevs if r <= bcache.tiprev)
else:
# nothing to fall back on, start empty.
bcache = branchcache()
revs.extend(cl.revs(start=bcache.tiprev + 1))
if revs:
bcache.update(repo, revs)
assert bcache.validfor(repo), filtername
repo._branchcaches[repo.filtername] = bcache
def replacecache(repo, bm):
"""Replace the branchmap cache for a repo with a branch mapping.
This is likely only called during clone with a branch map from a remote.
"""
cl = repo.changelog
clrev = cl.rev
clbranchinfo = cl.branchinfo
rbheads = []
closed = []
for bheads in bm.itervalues():
rbheads.extend(bheads)
for h in bheads:
r = clrev(h)
b, c = clbranchinfo(r)
if c:
closed.append(h)
if rbheads:
rtiprev = max((int(clrev(node))
for node in rbheads))
cache = branchcache(bm,
repo[rtiprev].node(),
rtiprev,
closednodes=closed)
# Try to stick it as low as possible
# filter above served are unlikely to be fetch from a clone
for candidate in ('base', 'immutable', 'served'):
rview = repo.filtered(candidate)
if cache.validfor(rview):
repo._branchcaches[candidate] = cache
cache.write(rview)
break
class branchcache(dict):
"""A dict like object that hold branches heads cache.
This cache is used to avoid costly computations to determine all the
branch heads of a repo.
The cache is serialized on disk in the following format:
<tip hex node> <tip rev number> [optional filtered repo hex hash]
<branch head hex node> <open/closed state> <branch name>
<branch head hex node> <open/closed state> <branch name>
...
The first line is used to check if the cache is still valid. If the
branch cache is for a filtered repo view, an optional third hash is
included that hashes the hashes of all filtered revisions.
The open/closed state is represented by a single letter 'o' or 'c'.
This field can be used to avoid changelog reads when determining if a
branch head closes a branch or not.
"""
@classmethod
def fromfile(cls, repo):
f = None
try:
f = repo.cachevfs(cls._filename(repo))
lineiter = iter(f)
cachekey = next(lineiter).rstrip('\n').split(" ", 2)
last, lrev = cachekey[:2]
last, lrev = bin(last), int(lrev)
filteredhash = None
if len(cachekey) > 2:
filteredhash = bin(cachekey[2])
bcache = cls(tipnode=last, tiprev=lrev, filteredhash=filteredhash)
if not bcache.validfor(repo):
# invalidate the cache
raise ValueError(r'tip differs')
cl = repo.changelog
for line in lineiter:
line = line.rstrip('\n')
if not line:
continue
node, state, label = line.split(" ", 2)
if state not in 'oc':
raise ValueError(r'invalid branch state')
label = encoding.tolocal(label.strip())
node = bin(node)
if not cl.hasnode(node):
raise ValueError(
r'node %s does not exist' % pycompat.sysstr(hex(node)))
bcache.setdefault(label, []).append(node)
if state == 'c':
bcache._closednodes.add(node)
except (IOError, OSError):
return None
except Exception as inst:
if repo.ui.debugflag:
msg = 'invalid branchheads cache'
if repo.filtername is not None:
msg += ' (%s)' % repo.filtername
msg += ': %s\n'
repo.ui.debug(msg % pycompat.bytestr(inst))
bcache = None
finally:
if f:
f.close()
return bcache
@staticmethod
def _filename(repo):
"""name of a branchcache file for a given repo or repoview"""
filename = "branch2"
if repo.filtername:
filename = '%s-%s' % (filename, repo.filtername)
return filename
def __init__(self, entries=(), tipnode=nullid, tiprev=nullrev,
filteredhash=None, closednodes=None):
super(branchcache, self).__init__(entries)
self.tipnode = tipnode
self.tiprev = tiprev
self.filteredhash = filteredhash
# closednodes is a set of nodes that close their branch. If the branch
# cache has been updated, it may contain nodes that are no longer
# heads.
if closednodes is None:
self._closednodes = set()
else:
self._closednodes = closednodes
def validfor(self, repo):
"""Is the cache content valid regarding a repo
- False when cached tipnode is unknown or if we detect a strip.
- True when cache is up to date or a subset of current repo."""
try:
return ((self.tipnode == repo.changelog.node(self.tiprev))
and (self.filteredhash == \
scmutil.filteredhash(repo, self.tiprev)))
except IndexError:
return False
def _branchtip(self, heads):
'''Return tuple with last open head in heads and false,
otherwise return last closed head and true.'''
tip = heads[-1]
closed = True
for h in reversed(heads):
if h not in self._closednodes:
tip = h
closed = False
break
return tip, closed
def branchtip(self, branch):
'''Return the tipmost open head on branch head, otherwise return the
tipmost closed head on branch.
Raise KeyError for unknown branch.'''
return self._branchtip(self[branch])[0]
def iteropen(self, nodes):
return (n for n in nodes if n not in self._closednodes)
def branchheads(self, branch, closed=False):
heads = self[branch]
if not closed:
heads = list(self.iteropen(heads))
return heads
def iterbranches(self):
for bn, heads in self.iteritems():
yield (bn, heads) + self._branchtip(heads)
def copy(self):
"""return an deep copy of the branchcache object"""
return type(self)(
self, self.tipnode, self.tiprev, self.filteredhash,
self._closednodes)
def write(self, repo):
try:
f = repo.cachevfs(self._filename(repo), "w", atomictemp=True)
cachekey = [hex(self.tipnode), '%d' % self.tiprev]
if self.filteredhash is not None:
cachekey.append(hex(self.filteredhash))
f.write(" ".join(cachekey) + '\n')
nodecount = 0
for label, nodes in sorted(self.iteritems()):
for node in nodes:
nodecount += 1
if node in self._closednodes:
state = 'c'
else:
state = 'o'
f.write("%s %s %s\n" % (hex(node), state,
encoding.fromlocal(label)))
f.close()
repo.ui.log('branchcache',
'wrote %s branch cache with %d labels and %d nodes\n',
repo.filtername, len(self), nodecount)
except (IOError, OSError, error.Abort) as inst:
# Abort may be raised by read only opener, so log and continue
repo.ui.debug("couldn't write branch cache: %s\n" %
stringutil.forcebytestr(inst))
def update(self, repo, revgen):
"""Given a branchhead cache, self, that may have extra nodes or be
missing heads, and a generator of nodes that are strictly a superset of
heads missing, this function updates self to be correct.
"""
starttime = util.timer()
cl = repo.changelog
# collect new branch entries
newbranches = {}
getbranchinfo = repo.revbranchcache().branchinfo
for r in revgen:
branch, closesbranch = getbranchinfo(r)
newbranches.setdefault(branch, []).append(r)
if closesbranch:
self._closednodes.add(cl.node(r))
# fetch current topological heads to speed up filtering
topoheads = set(cl.headrevs())
# if older branchheads are reachable from new ones, they aren't
# really branchheads. Note checking parents is insufficient:
# 1 (branch a) -> 2 (branch b) -> 3 (branch a)
for branch, newheadrevs in newbranches.iteritems():
bheads = self.setdefault(branch, [])
bheadset = set(cl.rev(node) for node in bheads)
# This have been tested True on all internal usage of this function.
# run it again in case of doubt
# assert not (set(bheadrevs) & set(newheadrevs))
bheadset.update(newheadrevs)
# This prunes out two kinds of heads - heads that are superseded by
# a head in newheadrevs, and newheadrevs that are not heads because
# an existing head is their descendant.
uncertain = bheadset - topoheads
if uncertain:
floorrev = min(uncertain)
ancestors = set(cl.ancestors(newheadrevs, floorrev))
bheadset -= ancestors
bheadrevs = sorted(bheadset)
self[branch] = [cl.node(rev) for rev in bheadrevs]
tiprev = bheadrevs[-1]
if tiprev > self.tiprev:
self.tipnode = cl.node(tiprev)
self.tiprev = tiprev
if not self.validfor(repo):
# cache key are not valid anymore
self.tipnode = nullid
self.tiprev = nullrev
for heads in self.values():
tiprev = max(cl.rev(node) for node in heads)
if tiprev > self.tiprev:
self.tipnode = cl.node(tiprev)
self.tiprev = tiprev
self.filteredhash = scmutil.filteredhash(repo, self.tiprev)
duration = util.timer() - starttime
repo.ui.log('branchcache', 'updated %s branch cache in %.4f seconds\n',
repo.filtername, duration)
self.write(repo)
class remotebranchcache(branchcache):
"""Branchmap info for a remote connection, should not write locally"""
def write(self, repo):
pass
# Revision branch info cache
_rbcversion = '-v1'
_rbcnames = 'rbc-names' + _rbcversion
_rbcrevs = 'rbc-revs' + _rbcversion
# [4 byte hash prefix][4 byte branch name number with sign bit indicating open]
_rbcrecfmt = '>4sI'
_rbcrecsize = calcsize(_rbcrecfmt)
_rbcnodelen = 4
_rbcbranchidxmask = 0x7fffffff
_rbccloseflag = 0x80000000
class revbranchcache(object):
"""Persistent cache, mapping from revision number to branch name and close.
This is a low level cache, independent of filtering.
Branch names are stored in rbc-names in internal encoding separated by 0.
rbc-names is append-only, and each branch name is only stored once and will
thus have a unique index.
The branch info for each revision is stored in rbc-revs as constant size
records. The whole file is read into memory, but it is only 'parsed' on
demand. The file is usually append-only but will be truncated if repo
modification is detected.
The record for each revision contains the first 4 bytes of the
corresponding node hash, and the record is only used if it still matches.
Even a completely trashed rbc-revs fill thus still give the right result
while converging towards full recovery ... assuming no incorrectly matching
node hashes.
The record also contains 4 bytes where 31 bits contains the index of the
branch and the last bit indicate that it is a branch close commit.
The usage pattern for rbc-revs is thus somewhat similar to 00changelog.i
and will grow with it but be 1/8th of its size.
"""
def __init__(self, repo, readonly=True):
assert repo.filtername is None
self._repo = repo
self._names = [] # branch names in local encoding with static index
self._rbcrevs = bytearray()
self._rbcsnameslen = 0 # length of names read at _rbcsnameslen
try:
bndata = repo.cachevfs.read(_rbcnames)
self._rbcsnameslen = len(bndata) # for verification before writing
if bndata:
self._names = [encoding.tolocal(bn)
for bn in bndata.split('\0')]
except (IOError, OSError):
if readonly:
# don't try to use cache - fall back to the slow path
self.branchinfo = self._branchinfo
if self._names:
try:
data = repo.cachevfs.read(_rbcrevs)
self._rbcrevs[:] = data
except (IOError, OSError) as inst:
repo.ui.debug("couldn't read revision branch cache: %s\n" %
stringutil.forcebytestr(inst))
# remember number of good records on disk
self._rbcrevslen = min(len(self._rbcrevs) // _rbcrecsize,
len(repo.changelog))
if self._rbcrevslen == 0:
self._names = []
self._rbcnamescount = len(self._names) # number of names read at
# _rbcsnameslen
def _clear(self):
self._rbcsnameslen = 0
del self._names[:]
self._rbcnamescount = 0
self._rbcrevslen = len(self._repo.changelog)
self._rbcrevs = bytearray(self._rbcrevslen * _rbcrecsize)
util.clearcachedproperty(self, '_namesreverse')
@util.propertycache
def _namesreverse(self):
return dict((b, r) for r, b in enumerate(self._names))
def branchinfo(self, rev):
"""Return branch name and close flag for rev, using and updating
persistent cache."""
changelog = self._repo.changelog
rbcrevidx = rev * _rbcrecsize
# avoid negative index, changelog.read(nullrev) is fast without cache
if rev == nullrev:
return changelog.branchinfo(rev)
# if requested rev isn't allocated, grow and cache the rev info
if len(self._rbcrevs) < rbcrevidx + _rbcrecsize:
return self._branchinfo(rev)
# fast path: extract data from cache, use it if node is matching
reponode = changelog.node(rev)[:_rbcnodelen]
cachenode, branchidx = unpack_from(
_rbcrecfmt, util.buffer(self._rbcrevs), rbcrevidx)
close = bool(branchidx & _rbccloseflag)
if close:
branchidx &= _rbcbranchidxmask
if cachenode == '\0\0\0\0':
pass
elif cachenode == reponode:
try:
return self._names[branchidx], close
except IndexError:
# recover from invalid reference to unknown branch
self._repo.ui.debug("referenced branch names not found"
" - rebuilding revision branch cache from scratch\n")
self._clear()
else:
# rev/node map has changed, invalidate the cache from here up
self._repo.ui.debug("history modification detected - truncating "
"revision branch cache to revision %d\n" % rev)
truncate = rbcrevidx + _rbcrecsize
del self._rbcrevs[truncate:]
self._rbcrevslen = min(self._rbcrevslen, truncate)
# fall back to slow path and make sure it will be written to disk
return self._branchinfo(rev)
def _branchinfo(self, rev):
"""Retrieve branch info from changelog and update _rbcrevs"""
changelog = self._repo.changelog
b, close = changelog.branchinfo(rev)
if b in self._namesreverse:
branchidx = self._namesreverse[b]
else:
branchidx = len(self._names)
self._names.append(b)
self._namesreverse[b] = branchidx
reponode = changelog.node(rev)
if close:
branchidx |= _rbccloseflag
self._setcachedata(rev, reponode, branchidx)
return b, close
def setdata(self, branch, rev, node, close):
"""add new data information to the cache"""
if branch in self._namesreverse:
branchidx = self._namesreverse[branch]
else:
branchidx = len(self._names)
self._names.append(branch)
self._namesreverse[branch] = branchidx
if close:
branchidx |= _rbccloseflag
self._setcachedata(rev, node, branchidx)
# If no cache data were readable (non exists, bad permission, etc)
# the cache was bypassing itself by setting:
#
# self.branchinfo = self._branchinfo
#
# Since we now have data in the cache, we need to drop this bypassing.
if r'branchinfo' in vars(self):
del self.branchinfo
def _setcachedata(self, rev, node, branchidx):
"""Writes the node's branch data to the in-memory cache data."""
if rev == nullrev:
return
rbcrevidx = rev * _rbcrecsize
if len(self._rbcrevs) < rbcrevidx + _rbcrecsize:
self._rbcrevs.extend('\0' *
(len(self._repo.changelog) * _rbcrecsize -
len(self._rbcrevs)))
pack_into(_rbcrecfmt, self._rbcrevs, rbcrevidx, node, branchidx)
self._rbcrevslen = min(self._rbcrevslen, rev)
tr = self._repo.currenttransaction()
if tr:
tr.addfinalize('write-revbranchcache', self.write)
def write(self, tr=None):
"""Save branch cache if it is dirty."""
repo = self._repo
wlock = None
step = ''
try:
if self._rbcnamescount < len(self._names):
step = ' names'
wlock = repo.wlock(wait=False)
if self._rbcnamescount != 0:
f = repo.cachevfs.open(_rbcnames, 'ab')
if f.tell() == self._rbcsnameslen:
f.write('\0')
else:
f.close()
repo.ui.debug("%s changed - rewriting it\n" % _rbcnames)
self._rbcnamescount = 0
self._rbcrevslen = 0
if self._rbcnamescount == 0:
# before rewriting names, make sure references are removed
repo.cachevfs.unlinkpath(_rbcrevs, ignoremissing=True)
f = repo.cachevfs.open(_rbcnames, 'wb')
f.write('\0'.join(encoding.fromlocal(b)
for b in self._names[self._rbcnamescount:]))
self._rbcsnameslen = f.tell()
f.close()
self._rbcnamescount = len(self._names)
start = self._rbcrevslen * _rbcrecsize
if start != len(self._rbcrevs):
step = ''
if wlock is None:
wlock = repo.wlock(wait=False)
revs = min(len(repo.changelog),
len(self._rbcrevs) // _rbcrecsize)
f = repo.cachevfs.open(_rbcrevs, 'ab')
if f.tell() != start:
repo.ui.debug("truncating cache/%s to %d\n"
% (_rbcrevs, start))
f.seek(start)
if f.tell() != start:
start = 0
f.seek(start)
f.truncate()
end = revs * _rbcrecsize
f.write(self._rbcrevs[start:end])
f.close()
self._rbcrevslen = revs
except (IOError, OSError, error.Abort, error.LockError) as inst:
repo.ui.debug("couldn't write revision branch cache%s: %s\n"
% (step, stringutil.forcebytestr(inst)))
finally:
if wlock is not None:
wlock.release()