exchangev2: fetch file revisions
Now that the server has an API for fetching file data, we can call into
it to fetch file revisions.
The implementation is relatively straightforward: we examine the
manifests that we fetched and find all new file revisions referenced
by them. We build up a mapping from file path to file nodes to
manifest node. (The mapping to first manifest node allows us to
map back to first changelog node/revision, which is used for the
linkrev.)
Once that map is built up, we iterate over it in a deterministic
manner and fetch and store file data. The code is very similar
to manifest fetching. So similar that we could probably extract the
common bits into a generic function.
With file data retrieval implemented, `hg clone` and `hg pull` are
effectively feature complete, at least as far as the completeness
of data transfer for essential repository data (changesets, manifests,
files, phases, and bookmarks). We're still missing support for
obsolescence markers, the hgtags fnodes cache, and the branchmap
cache. But these are non-essential for the moment (and will be
implemented later).
This is a good point to assess the state of exchangev2 in terms of
performance. I ran a local `hg clone` for the mozilla-unified
repository using both version 1 and version 2 of the wire protocols
and exchange methods. This is effectively comparing the performance
of the wire protocol overhead and "getbundle" versus domain-specific
commands. Wire protocol version 2 doesn't have compression implemented
yet. So I tested version 1 with `server.compressionengines=none` to
remove compression overhead from the equation.
server
before: user 220.420+0.000 sys 14.420+0.000
after: user 321.980+0.000 sys 18.990+0.000
client
before: real 561.650 secs (user 497.670+0.000 sys 28.160+0.000)
after: real 1226.260 secs (user 944.240+0.000 sys 354.150+0.000)
We have substantial regressions on both client and server. This
is obviously not desirable. I'm aware of some reasons:
* Lack of hgtagsfnodes transfer (contributes significant CPU to
client).
* Lack of branch cache transfer (contributes significant CPU to
client).
* Little to no profiling / optimization performed on wire protocol
version 2 code.
* There appears to be a memory leak on the client and that is likely
causing swapping on my machine.
* Using multiple threads on the client may be counter-productive because
Python.
* We're not compressing on the server.
* We're tracking file nodes on the client via manifest diffing
rather than using linkrev shortcuts on the server.
I'm pretty confident that most of these issues are addressable.
But even if we can't get wire protocol version 2 on performance parity
with "getbundle," I still think it is important to have the set of low
level data-specific retrieval commands that we have implemented so
far. This is because the existence of such commands allows flexibility
in how clients access server data.
Differential Revision: https://phab.mercurial-scm.org/D4491
# changelog bisection for mercurial
#
# Copyright 2007 Matt Mackall
# Copyright 2005, 2006 Benoit Boissinot <benoit.boissinot@ens-lyon.org>
#
# Inspired by git bisect, extension skeleton taken from mq.py.
#
# 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 collections
from .i18n import _
from .node import (
hex,
short,
)
from . import (
error,
)
def bisect(repo, state):
"""find the next node (if any) for testing during a bisect search.
returns a (nodes, number, good) tuple.
'nodes' is the final result of the bisect if 'number' is 0.
Otherwise 'number' indicates the remaining possible candidates for
the search and 'nodes' contains the next bisect target.
'good' is True if bisect is searching for a first good changeset, False
if searching for a first bad one.
"""
changelog = repo.changelog
clparents = changelog.parentrevs
skip = set([changelog.rev(n) for n in state['skip']])
def buildancestors(bad, good):
badrev = min([changelog.rev(n) for n in bad])
ancestors = collections.defaultdict(lambda: None)
for rev in repo.revs("descendants(%ln) - ancestors(%ln)", good, good):
ancestors[rev] = []
if ancestors[badrev] is None:
return badrev, None
return badrev, ancestors
good = False
badrev, ancestors = buildancestors(state['bad'], state['good'])
if not ancestors: # looking for bad to good transition?
good = True
badrev, ancestors = buildancestors(state['good'], state['bad'])
bad = changelog.node(badrev)
if not ancestors: # now we're confused
if (len(state['bad']) == 1 and len(state['good']) == 1 and
state['bad'] != state['good']):
raise error.Abort(_("starting revisions are not directly related"))
raise error.Abort(_("inconsistent state, %d:%s is good and bad")
% (badrev, short(bad)))
# build children dict
children = {}
visit = collections.deque([badrev])
candidates = []
while visit:
rev = visit.popleft()
if ancestors[rev] == []:
candidates.append(rev)
for prev in clparents(rev):
if prev != -1:
if prev in children:
children[prev].append(rev)
else:
children[prev] = [rev]
visit.append(prev)
candidates.sort()
# have we narrowed it down to one entry?
# or have all other possible candidates besides 'bad' have been skipped?
tot = len(candidates)
unskipped = [c for c in candidates if (c not in skip) and (c != badrev)]
if tot == 1 or not unskipped:
return ([changelog.node(c) for c in candidates], 0, good)
perfect = tot // 2
# find the best node to test
best_rev = None
best_len = -1
poison = set()
for rev in candidates:
if rev in poison:
# poison children
poison.update(children.get(rev, []))
continue
a = ancestors[rev] or [rev]
ancestors[rev] = None
x = len(a) # number of ancestors
y = tot - x # number of non-ancestors
value = min(x, y) # how good is this test?
if value > best_len and rev not in skip:
best_len = value
best_rev = rev
if value == perfect: # found a perfect candidate? quit early
break
if y < perfect and rev not in skip: # all downhill from here?
# poison children
poison.update(children.get(rev, []))
continue
for c in children.get(rev, []):
if ancestors[c]:
ancestors[c] = list(set(ancestors[c] + a))
else:
ancestors[c] = a + [c]
assert best_rev is not None
best_node = changelog.node(best_rev)
return ([best_node], tot, good)
def extendrange(repo, state, nodes, good):
# bisect is incomplete when it ends on a merge node and
# one of the parent was not checked.
parents = repo[nodes[0]].parents()
if len(parents) > 1:
if good:
side = state['bad']
else:
side = state['good']
num = len(set(i.node() for i in parents) & set(side))
if num == 1:
return parents[0].ancestor(parents[1])
return None
def load_state(repo):
state = {'current': [], 'good': [], 'bad': [], 'skip': []}
for l in repo.vfs.tryreadlines("bisect.state"):
kind, node = l[:-1].split()
node = repo.lookup(node)
if kind not in state:
raise error.Abort(_("unknown bisect kind %s") % kind)
state[kind].append(node)
return state
def save_state(repo, state):
f = repo.vfs("bisect.state", "w", atomictemp=True)
with repo.wlock():
for kind in sorted(state):
for node in state[kind]:
f.write("%s %s\n" % (kind, hex(node)))
f.close()
def resetstate(repo):
"""remove any bisect state from the repository"""
if repo.vfs.exists("bisect.state"):
repo.vfs.unlink("bisect.state")
def checkstate(state):
"""check we have both 'good' and 'bad' to define a range
Raise Abort exception otherwise."""
if state['good'] and state['bad']:
return True
if not state['good']:
raise error.Abort(_('cannot bisect (no known good revisions)'))
else:
raise error.Abort(_('cannot bisect (no known bad revisions)'))
def get(repo, status):
"""
Return a list of revision(s) that match the given status:
- ``good``, ``bad``, ``skip``: csets explicitly marked as good/bad/skip
- ``goods``, ``bads`` : csets topologically good/bad
- ``range`` : csets taking part in the bisection
- ``pruned`` : csets that are goods, bads or skipped
- ``untested`` : csets whose fate is yet unknown
- ``ignored`` : csets ignored due to DAG topology
- ``current`` : the cset currently being bisected
"""
state = load_state(repo)
if status in ('good', 'bad', 'skip', 'current'):
return map(repo.changelog.rev, state[status])
else:
# In the following sets, we do *not* call 'bisect()' with more
# than one level of recursion, because that can be very, very
# time consuming. Instead, we always develop the expression as
# much as possible.
# 'range' is all csets that make the bisection:
# - have a good ancestor and a bad descendant, or conversely
# that's because the bisection can go either way
range = '( bisect(bad)::bisect(good) | bisect(good)::bisect(bad) )'
_t = repo.revs('bisect(good)::bisect(bad)')
# The sets of topologically good or bad csets
if len(_t) == 0:
# Goods are topologically after bads
goods = 'bisect(good)::' # Pruned good csets
bads = '::bisect(bad)' # Pruned bad csets
else:
# Goods are topologically before bads
goods = '::bisect(good)' # Pruned good csets
bads = 'bisect(bad)::' # Pruned bad csets
# 'pruned' is all csets whose fate is already known: good, bad, skip
skips = 'bisect(skip)' # Pruned skipped csets
pruned = '( (%s) | (%s) | (%s) )' % (goods, bads, skips)
# 'untested' is all cset that are- in 'range', but not in 'pruned'
untested = '( (%s) - (%s) )' % (range, pruned)
# 'ignored' is all csets that were not used during the bisection
# due to DAG topology, but may however have had an impact.
# E.g., a branch merged between bads and goods, but whose branch-
# point is out-side of the range.
iba = '::bisect(bad) - ::bisect(good)' # Ignored bads' ancestors
iga = '::bisect(good) - ::bisect(bad)' # Ignored goods' ancestors
ignored = '( ( (%s) | (%s) ) - (%s) )' % (iba, iga, range)
if status == 'range':
return repo.revs(range)
elif status == 'pruned':
return repo.revs(pruned)
elif status == 'untested':
return repo.revs(untested)
elif status == 'ignored':
return repo.revs(ignored)
elif status == "goods":
return repo.revs(goods)
elif status == "bads":
return repo.revs(bads)
else:
raise error.ParseError(_('invalid bisect state'))
def label(repo, node):
rev = repo.changelog.rev(node)
# Try explicit sets
if rev in get(repo, 'good'):
# i18n: bisect changeset status
return _('good')
if rev in get(repo, 'bad'):
# i18n: bisect changeset status
return _('bad')
if rev in get(repo, 'skip'):
# i18n: bisect changeset status
return _('skipped')
if rev in get(repo, 'untested') or rev in get(repo, 'current'):
# i18n: bisect changeset status
return _('untested')
if rev in get(repo, 'ignored'):
# i18n: bisect changeset status
return _('ignored')
# Try implicit sets
if rev in get(repo, 'goods'):
# i18n: bisect changeset status
return _('good (implicit)')
if rev in get(repo, 'bads'):
# i18n: bisect changeset status
return _('bad (implicit)')
return None
def printresult(ui, repo, state, displayer, nodes, good):
if len(nodes) == 1:
# narrowed it down to a single revision
if good:
ui.write(_("The first good revision is:\n"))
else:
ui.write(_("The first bad revision is:\n"))
displayer.show(repo[nodes[0]])
extendnode = extendrange(repo, state, nodes, good)
if extendnode is not None:
ui.write(_('Not all ancestors of this changeset have been'
' checked.\nUse bisect --extend to continue the '
'bisection from\nthe common ancestor, %s.\n')
% extendnode)
else:
# multiple possible revisions
if good:
ui.write(_("Due to skipped revisions, the first "
"good revision could be any of:\n"))
else:
ui.write(_("Due to skipped revisions, the first "
"bad revision could be any of:\n"))
for n in nodes:
displayer.show(repo[n])
displayer.close()