rust: peek_mut optim for lazy ancestors
This is one of the two optimizations that are also
present in the Python code: replacing pairs of pop/push
on the BinaryHeap by single updates, hence having it
under the hood maintain its consistency (sift) only once.
On Mozilla central, the measured gain (see details below)
is around 7%.
Creating the PeekMut object by calling peek_mut() right away
instead of peek() first is less efficient (gain is only 4%, stats
not included).
Our interpretation is that its creation has a cost which is vasted
in the cases where it ends by droping the value (Peekmut::pop()
just does self.heap.pop() anyway). On the other hand, the immutable
peek() is very fast: it's just taking a reference in the
underlying vector.
The Python version still has another optimization:
if parent(current) == current-1, then the heap doesn't need
to maintain its consistency, since we already know that
it's bigger than all the others in the heap.
Rust's BinaryHeap doesn't allow us to mutate its biggest
element with no housekeeping, but we tried it anyway, with a
copy of the BinaryHeap implementation with a dedicaded added
method: it's not worth the technical debt in our opinion
(we measured only a further 1.6% improvement).
One possible explanation would be that the sift is really fast
anyway in that case, whereas it's not in the case of Python,
because it's at least partly done in slow Python code.
Still it's possible that replacing BinaryHeap by something more
dedicated to discrete ordered types could be faster.
Measurements on mozilla-central:
Three runs of 'hg perfancestors' on the parent changeset:
Moyenne des médianes: 0.100587
! wall 0.100062 comb 0.100000 user 0.100000 sys 0.000000 (best of 98)
! wall 0.135804 comb 0.130000 user 0.130000 sys 0.000000 (max of 98)
! wall 0.102864 comb 0.102755 user 0.099286 sys 0.003469 (avg of 98)
! wall 0.101486 comb 0.110000 user 0.110000 sys 0.000000 (median of 98)
! wall 0.096804 comb 0.090000 user 0.090000 sys 0.000000 (best of 100)
! wall 0.132235 comb 0.130000 user 0.120000 sys 0.010000 (max of 100)
! wall 0.100258 comb 0.100300 user 0.096000 sys 0.004300 (avg of 100)
! wall 0.098384 comb 0.100000 user 0.100000 sys 0.000000 (median of 100)
! wall 0.099925 comb 0.100000 user 0.100000 sys 0.000000 (best of 98)
! wall 0.133518 comb 0.140000 user 0.130000 sys 0.010000 (max of 98)
! wall 0.102381 comb 0.102449 user 0.098265 sys 0.004184 (avg of 98)
! wall 0.101891 comb 0.090000 user 0.090000 sys 0.000000 (median of 98)
Mean of the medians: 0.100587
On the present changeset:
! wall 0.091344 comb 0.090000 user 0.090000 sys 0.000000 (best of 100)
! wall 0.122728 comb 0.120000 user 0.110000 sys 0.010000 (max of 100)
! wall 0.093268 comb 0.093300 user 0.089300 sys 0.004000 (avg of 100)
! wall 0.092567 comb 0.100000 user 0.090000 sys 0.010000 (median of 100)
! wall 0.093294 comb 0.080000 user 0.080000 sys 0.000000 (best of 100)
! wall 0.144887 comb 0.150000 user 0.140000 sys 0.010000 (max of 100)
! wall 0.097708 comb 0.097700 user 0.093400 sys 0.004300 (avg of 100)
! wall 0.094980 comb 0.100000 user 0.090000 sys 0.010000 (median of 100)
! wall 0.091262 comb 0.090000 user 0.080000 sys 0.010000 (best of 100)
! wall 0.123772 comb 0.130000 user 0.120000 sys 0.010000 (max of 100)
! wall 0.093188 comb 0.093200 user 0.089300 sys 0.003900 (avg of 100)
! wall 0.092364 comb 0.100000 user 0.090000 sys 0.010000 (median of 100)
Mean of the medians is 0.0933
Differential Revision: https://phab.mercurial-scm.org/D5358
# drawdag.py - convert ASCII revision DAG to actual changesets
#
# Copyright 2016 Facebook, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
"""
create changesets from an ASCII graph for testing purpose.
For example, given the following input::
c d
|/
b
|
a
4 changesets and 4 local tags will be created.
`hg log -G -T "{rev} {desc} (tag: {tags})"` will output::
o 3 d (tag: d tip)
|
| o 2 c (tag: c)
|/
o 1 b (tag: b)
|
o 0 a (tag: a)
For root nodes (nodes without parents) in the graph, they can be revsets
pointing to existing nodes. The ASCII graph could also have disconnected
components with same names referring to the same changeset.
Therefore, given the repo having the 4 changesets (and tags) above, with the
following ASCII graph as input::
foo bar bar foo
| / | |
ancestor(c,d) a baz
The result (`hg log -G -T "{desc}"`) will look like::
o foo
|\
+---o bar
| | |
| o | baz
| /
+---o d
| |
+---o c
| |
o | b
|/
o a
Note that if you take the above `hg log` output directly as input. It will work
as expected - the result would be an isomorphic graph::
o foo
|\
| | o d
| |/
| | o c
| |/
| | o bar
| |/|
| o | b
| |/
o / baz
/
o a
This is because 'o' is specially handled in the input: instead of using 'o' as
the node name, the word to the right will be used.
Some special comments could have side effects:
- Create obsmarkers
# replace: A -> B -> C -> D # chained 1 to 1 replacements
# split: A -> B, C # 1 to many
# prune: A, B, C # many to nothing
"""
from __future__ import absolute_import, print_function
import collections
import itertools
import re
from mercurial.i18n import _
from mercurial import (
context,
error,
node,
obsolete,
pycompat,
registrar,
scmutil,
tags as tagsmod,
)
cmdtable = {}
command = registrar.command(cmdtable)
_pipechars = b'\\/+-|'
_nonpipechars = b''.join(pycompat.bytechr(i) for i in range(33, 127)
if pycompat.bytechr(i) not in _pipechars)
def _isname(ch):
"""char -> bool. return True if ch looks like part of a name, False
otherwise"""
return ch in _nonpipechars
def _parseasciigraph(text):
r"""str -> {str : [str]}. convert the ASCII graph to edges
>>> import pprint
>>> pprint.pprint({pycompat.sysstr(k): [pycompat.sysstr(vv) for vv in v]
... for k, v in _parseasciigraph(br'''
... G
... |
... I D C F # split: B -> E, F, G
... \ \| | # replace: C -> D -> H
... H B E # prune: F, I
... \|/
... A
... ''').items()})
{'A': [],
'B': ['A'],
'C': ['B'],
'D': ['B'],
'E': ['A'],
'F': ['E'],
'G': ['F'],
'H': ['A'],
'I': ['H']}
>>> pprint.pprint({pycompat.sysstr(k): [pycompat.sysstr(vv) for vv in v]
... for k, v in _parseasciigraph(br'''
... o foo
... |\
... +---o bar
... | | |
... | o | baz
... | /
... +---o d
... | |
... +---o c
... | |
... o | b
... |/
... o a
... ''').items()})
{'a': [],
'b': ['a'],
'bar': ['b', 'a'],
'baz': [],
'c': ['b'],
'd': ['b'],
'foo': ['baz', 'b']}
"""
lines = text.splitlines()
edges = collections.defaultdict(list) # {node: []}
def get(y, x):
"""(int, int) -> char. give a coordinate, return the char. return a
space for anything out of range"""
if x < 0 or y < 0:
return b' '
try:
return lines[y][x:x + 1] or b' '
except IndexError:
return b' '
def getname(y, x):
"""(int, int) -> str. like get(y, x) but concatenate left and right
parts. if name is an 'o', try to replace it to the right"""
result = b''
for i in itertools.count(0):
ch = get(y, x - i)
if not _isname(ch):
break
result = ch + result
for i in itertools.count(1):
ch = get(y, x + i)
if not _isname(ch):
break
result += ch
if result == b'o':
# special handling, find the name to the right
result = b''
for i in itertools.count(2):
ch = get(y, x + i)
if ch == b' ' or ch in _pipechars:
if result or x + i >= len(lines[y]):
break
else:
result += ch
return result or b'o'
return result
def parents(y, x):
"""(int, int) -> [str]. follow the ASCII edges at given position,
return a list of parents"""
visited = {(y, x)}
visit = []
result = []
def follow(y, x, expected):
"""conditionally append (y, x) to visit array, if it's a char
in excepted. 'o' in expected means an '_isname' test.
if '-' (or '+') is not in excepted, and get(y, x) is '-' (or '+'),
the next line (y + 1, x) will be checked instead."""
ch = get(y, x)
if any(ch == c and c not in expected for c in (b'-', b'+')):
y += 1
return follow(y + 1, x, expected)
if ch in expected or (b'o' in expected and _isname(ch)):
visit.append((y, x))
# -o- # starting point:
# /|\ # follow '-' (horizontally), and '/|\' (to the bottom)
follow(y + 1, x, b'|')
follow(y + 1, x - 1, b'/')
follow(y + 1, x + 1, b'\\')
follow(y, x - 1, b'-')
follow(y, x + 1, b'-')
while visit:
y, x = visit.pop()
if (y, x) in visited:
continue
visited.add((y, x))
ch = get(y, x)
if _isname(ch):
result.append(getname(y, x))
continue
elif ch == b'|':
follow(y + 1, x, b'/|o')
follow(y + 1, x - 1, b'/')
follow(y + 1, x + 1, b'\\')
elif ch == b'+':
follow(y, x - 1, b'-')
follow(y, x + 1, b'-')
follow(y + 1, x - 1, b'/')
follow(y + 1, x + 1, b'\\')
follow(y + 1, x, b'|')
elif ch == b'\\':
follow(y + 1, x + 1, b'\\|o')
elif ch == b'/':
follow(y + 1, x - 1, b'/|o')
elif ch == b'-':
follow(y, x - 1, b'-+o')
follow(y, x + 1, b'-+o')
return result
for y, line in enumerate(lines):
for x, ch in enumerate(pycompat.bytestr(line)):
if ch == b'#': # comment
break
if _isname(ch):
edges[getname(y, x)] += parents(y, x)
return dict(edges)
class simplefilectx(object):
def __init__(self, path, data):
self._data = data
self._path = path
def data(self):
return self._data
def filenode(self):
return None
def path(self):
return self._path
def renamed(self):
return None
def flags(self):
return b''
class simplecommitctx(context.committablectx):
def __init__(self, repo, name, parentctxs, added):
opts = {
'changes': scmutil.status([], list(added), [], [], [], [], []),
'date': b'0 0',
'extra': {b'branch': b'default'},
}
super(simplecommitctx, self).__init__(repo, name, **opts)
self._added = added
self._parents = parentctxs
while len(self._parents) < 2:
self._parents.append(repo[node.nullid])
def filectx(self, key):
return simplefilectx(key, self._added[key])
def commit(self):
return self._repo.commitctx(self)
def _walkgraph(edges):
"""yield node, parents in topologically order"""
visible = set(edges.keys())
remaining = {} # {str: [str]}
for k, vs in edges.items():
for v in vs:
if v not in remaining:
remaining[v] = []
remaining[k] = vs[:]
while remaining:
leafs = [k for k, v in remaining.items() if not v]
if not leafs:
raise error.Abort(_('the graph has cycles'))
for leaf in sorted(leafs):
if leaf in visible:
yield leaf, edges[leaf]
del remaining[leaf]
for k, v in remaining.items():
if leaf in v:
v.remove(leaf)
def _getcomments(text):
"""
>>> [pycompat.sysstr(s) for s in _getcomments(br'''
... G
... |
... I D C F # split: B -> E, F, G
... \ \| | # replace: C -> D -> H
... H B E # prune: F, I
... \|/
... A
... ''')]
['split: B -> E, F, G', 'replace: C -> D -> H', 'prune: F, I']
"""
for line in text.splitlines():
if b' # ' not in line:
continue
yield line.split(b' # ', 1)[1].split(b' # ')[0].strip()
@command(b'debugdrawdag', [])
def debugdrawdag(ui, repo, **opts):
"""read an ASCII graph from stdin and create changesets
The ASCII graph is like what :hg:`log -G` outputs, with each `o` replaced
to the name of the node. The command will create dummy changesets and local
tags with those names to make the dummy changesets easier to be referred
to.
If the name of a node is a single character 'o', It will be replaced by the
word to the right. This makes it easier to reuse
:hg:`log -G -T '{desc}'` outputs.
For root (no parents) nodes, revset can be used to query existing repo.
Note that the revset cannot have confusing characters which can be seen as
the part of the graph edges, like `|/+-\`.
"""
text = ui.fin.read()
# parse the graph and make sure len(parents) <= 2 for each node
edges = _parseasciigraph(text)
for k, v in edges.items():
if len(v) > 2:
raise error.Abort(_('%s: too many parents: %s')
% (k, b' '.join(v)))
# parse comments to get extra file content instructions
files = collections.defaultdict(dict) # {(name, path): content}
comments = list(_getcomments(text))
filere = re.compile(br'^(\w+)/([\w/]+)\s*=\s*(.*)$', re.M)
for name, path, content in filere.findall(b'\n'.join(comments)):
content = content.replace(br'\n', b'\n').replace(br'\1', b'\1')
files[name][path] = content
committed = {None: node.nullid} # {name: node}
# for leaf nodes, try to find existing nodes in repo
for name, parents in edges.items():
if len(parents) == 0:
try:
committed[name] = scmutil.revsingle(repo, name)
except error.RepoLookupError:
pass
# commit in topological order
for name, parents in _walkgraph(edges):
if name in committed:
continue
pctxs = [repo[committed[n]] for n in parents]
pctxs.sort(key=lambda c: c.node())
added = {}
if len(parents) > 1:
# If it's a merge, take the files and contents from the parents
for f in pctxs[1].manifest():
if f not in pctxs[0].manifest():
added[f] = pctxs[1][f].data()
else:
# If it's not a merge, add a single file
added[name] = name
# add extra file contents in comments
for path, content in files.get(name, {}).items():
added[path] = content
ctx = simplecommitctx(repo, name, pctxs, added)
n = ctx.commit()
committed[name] = n
tagsmod.tag(repo, [name], n, message=None, user=None, date=None,
local=True)
# handle special comments
with repo.wlock(), repo.lock(), repo.transaction(b'drawdag'):
getctx = lambda x: repo.unfiltered()[committed[x.strip()]]
for comment in comments:
rels = [] # obsolete relationships
args = comment.split(b':', 1)
if len(args) <= 1:
continue
cmd = args[0].strip()
arg = args[1].strip()
if cmd in (b'replace', b'rebase', b'amend'):
nodes = [getctx(m) for m in arg.split(b'->')]
for i in range(len(nodes) - 1):
rels.append((nodes[i], (nodes[i + 1],)))
elif cmd in (b'split',):
pre, succs = arg.split(b'->')
succs = succs.split(b',')
rels.append((getctx(pre), (getctx(s) for s in succs)))
elif cmd in (b'prune',):
for n in arg.split(b','):
rels.append((getctx(n), ()))
if rels:
obsolete.createmarkers(repo, rels, date=(0, 0), operation=cmd)