Mercurial > hg
view mercurial/narrowspec.py @ 39506:b66ea3fc3a86
sparse-revlog: set max delta chain length to on thousand
The new snapshot system used in the sparse-revlog case gave us some small size
benefit so far. However its most important property is to gracefully handle
harder limit on delta chainlength.
Long delta chain has a very detrimental impact on read (and write) performance
in revlog. Being able to shorter them provide a great boost. However, shorting
delta used to result significantly lower compression ratio. The intermediate
snapshots effectively suppress most of this effect (even all in some case).
# Effect on the test repository
The repository we use for test is not "realistic" but can still show this in
action using an unreasonably low chain limit. Limiting the chain length show a
sizeable increase but stay under control: +6% for limit=15; +15% for limit=10.
Without the snapshot system the increase is significantly bigger: +45% for
limit=15; +80% for limit=10. Even slightly larger than without delta chain
limit, the resulting size is still smaller than before we started doing
snapshots.
Here is a table for comparison. *Since the repository is not branchy, the
initial sparse-revlog version does not bring much benefit compare to the
non-sparse one):
chain length limit | none | limit=15 | limit=10 |
without sparse-revlog | 62 818 987 | 112 664 615 | 131 222 574 |
without snapshot | 74 365 490 | 108 211 410 | 133 857 764 |
with snapshot | 59 230 936 | 63 002 924 | 68 415 329 |
# Effect On Real Life Repositories
The series provides significant benefits on all kind of repositories.
Using `hg debugupgraderepo -o redeltaparent --run`, we recomputed delta chain
for various repositories with different settings:
- delta chain length: unlimited or 1000 limit
- sparse-revlog: enabled or disabled
- this series: applied or not applied
We can observe multiple types of effect:
- On very branchy repositories:
* The delta chain limit as low impact on the repo size.
* Intermediate snapshot greatly reduces manifest size:
- pypy: -80%
- netbeans: -95%
* The delta chain limit is effective, without a size impact:
- netbeans average: 613 -> 282
- private #1 average: 1 068 -> 307
- On more linear repository:
* Intermediate snapshot limit the impact of delta chain limit:
- mozilla:
without the series: +360%
with the series: +25%
* The delta chain limit provides large improvement:
- mozilla's average chain length:
unlimited: 15 338
limited: 469
* Despite the chain length limit, the manifest size is reduced:
- mercurial: -25%
- mozilla: -30%
It is clear that the use of chains of intermediate snapshots provide large
benefits both in storage size and delta chains quality. We should now switch our
effort toward making sure the write performance are acceptable. Then,
`sparse-revlog` will be a suitable format for all new repository.
# Raw Statistic
* no-sparse: general delta repository not using sparse-revlog
* no-snapshot: sparse-revlog repository not using this series
* snapshot: sparse-revlog repository using this series
mercurial
Manifest Size:
limit | none | 1000
------------|-------------|------------
no-sparse | 8 021 373 | 8 199 366
no-snapshot | 8 103 561 | 8 259 719
snapshot | 6 137 116 | 6 126 433
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 307 | 1456 || 279 | 1000 ||
no-snapshot || 312 | 1456 || 283 | 1000 ||
snapshot || 248 | 1208 || 241 | 1000 ||
Full Store Size
limit | none | 1000
------------|-------------|------------
no-sparse | 51 013 198 | 51 201 574
no-snapshot | 50 930 795 | 51 141 006
snapshot | 48 072 037 | 48 093 572
pypy
Manifest Size:
limit | none | 1000
------------|-------------|------------
no-sparse | 193 987 784 | 193 987 784
no-snapshot | 163 171 745 | 163 312 229
snapshot | 34 605 900 | 34 600 750
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 101 | 692 || 101 | 692 ||
no-snapshot || 151 | 1307 || 148 | 1000 ||
snapshot || 128 | 1309 || 125 | 1000 ||
Full Store Size
limit | none | 1000
------------|-------------|------------
no-sparse | 495 931 473 | 495 931 473
no-snapshot | 465 441 017 | 465 581 501
snapshot | 355 467 301 | 355 472 451
Mozilla
Manifest Size:
limit | none | 1000
------------|----------------|---------------
no-sparse | 416 757 148 | 1 869 009 668
no-snapshot | 401 592 370 | 1 843 493 795
snapshot | 224 359 521 | 284 615 500
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 15 333 | 58 980 || 468 | 1 000 ||
no-snapshot || 15 336 | 58 980 || 469 | 1 000 ||
snapshot || 15 338 | 58 983 || 469 | 1 000 ||
Full Store Size
limit | none | 1000
------------|----------------|---------------
no-sparse | 2 712 477 887 | 4 164 995 451
no-snapshot | 2 698 887 835 | 4 141 054 304
snapshot | 2 518 130 385 | 2 578 587 596
Netbeans
Manifest Size:
limit | none | 1000
------------|----------------|---------------
no-sparse | 4 766 794 101 | 4 870 642 687
no-snapshot | 4 334 806 082 | 4 428 681 309
snapshot | 232 659 666 | 240 330 665
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 597 | 6802 || 254 | 1 000 ||
no-snapshot || 648 | 6 802 || 305 | 1 000 ||
snapshot || 613 | 6 804 || 282 | 1 000 ||
Full Store Size
limit | none | 1000
------------|----------------|---------------
no-sparse | 5 807 347 998 | 5 911 196 584
no-snapshot | 5 375 398 602 | 5 469 273 829
snapshot | 1 282 519 928 | 1 290 190 927
Private repo #1
Manifest Size:
limit | none | 1000
------------|-----------------|---------------
no-sparse | 41 389 010 840 | 41 398 162 091
no-snapshot | 9 737 319 435 | 10 223 773 150
snapshot | 744 215 807 | 747 961 822
Manifest Chain length data
limit || none || 1000 ||
value || average | max || average | max ||
------------||---------|---------||---------|---------||
no-sparse || 245 | 8 885 || 81 | 1 000 ||
no-snapshot || 1 225 | 8 885 || 336 | 1 000 ||
snapshot || 1 068 | 7 909 || 307 | 1 000 ||
Full Store Size
limit | none | 1000
------------|----------------|---------------
no-sparse | 49 646 065 126 | 49 655 216 377
no-snapshot | 17 924 862 856 | 18 411 316 571
snapshot | 9 009 024 710 | 9 012 770 725
Private repo #2
We currently have less data available for that repository.
* Before is a sparse-revlog repository without this series
* After is a sparse-revlog repository with this series + 1000 chain limit
Manifest Size:
Before: 1 531 485 040 bytes
After: 1 091 422 451 bytes
Manifest Chain:
Before: 2 218 avg; 6 575 Max
After: 442 avg; 1 000 Max
Full Store Size
Before: 15 203 955 615
after: 8 207 180 693
author | Boris Feld <boris.feld@octobus.net> |
---|---|
date | Fri, 07 Sep 2018 11:18:45 -0400 |
parents | 576eef1ab43d |
children | 2675d561f5cb |
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# narrowspec.py - methods for working with a narrow view of a repository # # Copyright 2017 Google, Inc. # # 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 errno from .i18n import _ from . import ( error, match as matchmod, repository, sparse, util, ) FILENAME = 'narrowspec' def parseserverpatterns(text): """Parses the narrowspec format that's returned by the server.""" includepats = set() excludepats = set() # We get one entry per line, in the format "<key> <value>". # It's OK for value to contain other spaces. for kp in (l.split(' ', 1) for l in text.splitlines()): if len(kp) != 2: raise error.Abort(_('Invalid narrowspec pattern line: "%s"') % kp) key = kp[0] pat = kp[1] if key == 'include': includepats.add(pat) elif key == 'exclude': excludepats.add(pat) else: raise error.Abort(_('Invalid key "%s" in server response') % key) return includepats, excludepats def normalizesplitpattern(kind, pat): """Returns the normalized version of a pattern and kind. Returns a tuple with the normalized kind and normalized pattern. """ pat = pat.rstrip('/') _validatepattern(pat) return kind, pat def _numlines(s): """Returns the number of lines in s, including ending empty lines.""" # We use splitlines because it is Unicode-friendly and thus Python 3 # compatible. However, it does not count empty lines at the end, so trick # it by adding a character at the end. return len((s + 'x').splitlines()) def _validatepattern(pat): """Validates the pattern and aborts if it is invalid. Patterns are stored in the narrowspec as newline-separated POSIX-style bytestring paths. There's no escaping. """ # We use newlines as separators in the narrowspec file, so don't allow them # in patterns. if _numlines(pat) > 1: raise error.Abort(_('newlines are not allowed in narrowspec paths')) components = pat.split('/') if '.' in components or '..' in components: raise error.Abort(_('"." and ".." are not allowed in narrowspec paths')) def normalizepattern(pattern, defaultkind='path'): """Returns the normalized version of a text-format pattern. If the pattern has no kind, the default will be added. """ kind, pat = matchmod._patsplit(pattern, defaultkind) return '%s:%s' % normalizesplitpattern(kind, pat) def parsepatterns(pats): """Parses a list of patterns into a typed pattern set.""" return set(normalizepattern(p) for p in pats) def format(includes, excludes): output = '[include]\n' for i in sorted(includes - excludes): output += i + '\n' output += '[exclude]\n' for e in sorted(excludes): output += e + '\n' return output def match(root, include=None, exclude=None): if not include: # Passing empty include and empty exclude to matchmod.match() # gives a matcher that matches everything, so explicitly use # the nevermatcher. return matchmod.never(root, '') return matchmod.match(root, '', [], include=include or [], exclude=exclude or []) def needsexpansion(includes): return [i for i in includes if i.startswith('include:')] def load(repo): try: spec = repo.svfs.read(FILENAME) except IOError as e: # Treat "narrowspec does not exist" the same as "narrowspec file exists # and is empty". if e.errno == errno.ENOENT: return set(), set() raise # maybe we should care about the profiles returned too includepats, excludepats, profiles = sparse.parseconfig(repo.ui, spec, 'narrow') if profiles: raise error.Abort(_("including other spec files using '%include' is not" " suported in narrowspec")) return includepats, excludepats def save(repo, includepats, excludepats): spec = format(includepats, excludepats) repo.svfs.write(FILENAME, spec) def savebackup(repo, backupname): if repository.NARROW_REQUIREMENT not in repo.requirements: return vfs = repo.vfs vfs.tryunlink(backupname) util.copyfile(repo.svfs.join(FILENAME), vfs.join(backupname), hardlink=True) def restorebackup(repo, backupname): if repository.NARROW_REQUIREMENT not in repo.requirements: return util.rename(repo.vfs.join(backupname), repo.svfs.join(FILENAME)) def clearbackup(repo, backupname): if repository.NARROW_REQUIREMENT not in repo.requirements: return repo.vfs.unlink(backupname) def restrictpatterns(req_includes, req_excludes, repo_includes, repo_excludes): r""" Restricts the patterns according to repo settings, results in a logical AND operation :param req_includes: requested includes :param req_excludes: requested excludes :param repo_includes: repo includes :param repo_excludes: repo excludes :return: include patterns, exclude patterns, and invalid include patterns. >>> restrictpatterns({'f1','f2'}, {}, ['f1'], []) (set(['f1']), {}, []) >>> restrictpatterns({'f1'}, {}, ['f1','f2'], []) (set(['f1']), {}, []) >>> restrictpatterns({'f1/fc1', 'f3/fc3'}, {}, ['f1','f2'], []) (set(['f1/fc1']), {}, []) >>> restrictpatterns({'f1_fc1'}, {}, ['f1','f2'], []) ([], set(['path:.']), []) >>> restrictpatterns({'f1/../f2/fc2'}, {}, ['f1','f2'], []) (set(['f2/fc2']), {}, []) >>> restrictpatterns({'f1/../f3/fc3'}, {}, ['f1','f2'], []) ([], set(['path:.']), []) >>> restrictpatterns({'f1/$non_exitent_var'}, {}, ['f1','f2'], []) (set(['f1/$non_exitent_var']), {}, []) """ res_excludes = set(req_excludes) res_excludes.update(repo_excludes) invalid_includes = [] if not req_includes: res_includes = set(repo_includes) elif 'path:.' not in repo_includes: res_includes = [] for req_include in req_includes: req_include = util.expandpath(util.normpath(req_include)) if req_include in repo_includes: res_includes.append(req_include) continue valid = False for repo_include in repo_includes: if req_include.startswith(repo_include + '/'): valid = True res_includes.append(req_include) break if not valid: invalid_includes.append(req_include) if len(res_includes) == 0: res_excludes = {'path:.'} else: res_includes = set(res_includes) else: res_includes = set(req_includes) return res_includes, res_excludes, invalid_includes