Mercurial > hg
view mercurial/registrar.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 | 5d3b58472660 |
children | 170926caf44c |
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# registrar.py - utilities to register function for specific purpose # # Copyright FUJIWARA Katsunori <foozy@lares.dti.ne.jp> and others # # 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 from . import ( configitems, error, pycompat, util, ) # unlike the other registered items, config options are neither functions or # classes. Registering the option is just small function call. # # We still add the official API to the registrar module for consistency with # the other items extensions want might to register. configitem = configitems.getitemregister class _funcregistrarbase(object): """Base of decorator to register a function for specific purpose This decorator stores decorated functions into own dict 'table'. The least derived class can be defined by overriding 'formatdoc', for example:: class keyword(_funcregistrarbase): _docformat = ":%s: %s" This should be used as below: keyword = registrar.keyword() @keyword('bar') def barfunc(*args, **kwargs): '''Explanation of bar keyword .... ''' pass In this case: - 'barfunc' is stored as 'bar' in '_table' of an instance 'keyword' above - 'barfunc.__doc__' becomes ":bar: Explanation of bar keyword" """ def __init__(self, table=None): if table is None: self._table = {} else: self._table = table def __call__(self, decl, *args, **kwargs): return lambda func: self._doregister(func, decl, *args, **kwargs) def _doregister(self, func, decl, *args, **kwargs): name = self._getname(decl) if name in self._table: msg = 'duplicate registration for name: "%s"' % name raise error.ProgrammingError(msg) if func.__doc__ and not util.safehasattr(func, '_origdoc'): doc = pycompat.sysbytes(func.__doc__).strip() func._origdoc = doc func.__doc__ = pycompat.sysstr(self._formatdoc(decl, doc)) self._table[name] = func self._extrasetup(name, func, *args, **kwargs) return func def _parsefuncdecl(self, decl): """Parse function declaration and return the name of function in it """ i = decl.find('(') if i >= 0: return decl[:i] else: return decl def _getname(self, decl): """Return the name of the registered function from decl Derived class should override this, if it allows more descriptive 'decl' string than just a name. """ return decl _docformat = None def _formatdoc(self, decl, doc): """Return formatted document of the registered function for help 'doc' is '__doc__.strip()' of the registered function. """ return self._docformat % (decl, doc) def _extrasetup(self, name, func): """Execute exra setup for registered function, if needed """ class command(_funcregistrarbase): """Decorator to register a command function to table This class receives a command table as its argument. The table should be a dict. The created object can be used as a decorator for adding commands to that command table. This accepts multiple arguments to define a command. The first argument is the command name (as bytes). The `options` keyword argument is an iterable of tuples defining command arguments. See ``mercurial.fancyopts.fancyopts()`` for the format of each tuple. The `synopsis` argument defines a short, one line summary of how to use the command. This shows up in the help output. There are three arguments that control what repository (if any) is found and passed to the decorated function: `norepo`, `optionalrepo`, and `inferrepo`. The `norepo` argument defines whether the command does not require a local repository. Most commands operate against a repository, thus the default is False. When True, no repository will be passed. The `optionalrepo` argument defines whether the command optionally requires a local repository. If no repository can be found, None will be passed to the decorated function. The `inferrepo` argument defines whether to try to find a repository from the command line arguments. If True, arguments will be examined for potential repository locations. See ``findrepo()``. If a repository is found, it will be used and passed to the decorated function. The `intents` argument defines a set of intended actions or capabilities the command is taking. These intents can be used to affect the construction of the repository object passed to the command. For example, commands declaring that they are read-only could receive a repository that doesn't have any methods allowing repository mutation. Other intents could be used to prevent the command from running if the requested intent could not be fulfilled. The following intents are defined: readonly The command is read-only The signature of the decorated function looks like this: def cmd(ui[, repo] [, <args>] [, <options>]) `repo` is required if `norepo` is False. `<args>` are positional args (or `*args`) arguments, of non-option arguments from the command line. `<options>` are keyword arguments (or `**options`) of option arguments from the command line. See the WritingExtensions and MercurialApi documentation for more exhaustive descriptions and examples. """ def _doregister(self, func, name, options=(), synopsis=None, norepo=False, optionalrepo=False, inferrepo=False, intents=None): func.norepo = norepo func.optionalrepo = optionalrepo func.inferrepo = inferrepo func.intents = intents or set() if synopsis: self._table[name] = func, list(options), synopsis else: self._table[name] = func, list(options) return func INTENT_READONLY = b'readonly' class revsetpredicate(_funcregistrarbase): """Decorator to register revset predicate Usage:: revsetpredicate = registrar.revsetpredicate() @revsetpredicate('mypredicate(arg1, arg2[, arg3])') def mypredicatefunc(repo, subset, x): '''Explanation of this revset predicate .... ''' pass The first string argument is used also in online help. Optional argument 'safe' indicates whether a predicate is safe for DoS attack (False by default). Optional argument 'takeorder' indicates whether a predicate function takes ordering policy as the last argument. Optional argument 'weight' indicates the estimated run-time cost, useful for static optimization, default is 1. Higher weight means more expensive. Usually, revsets that are fast and return only one revision has a weight of 0.5 (ex. a symbol); revsets with O(changelog) complexity and read only the changelog have weight 10 (ex. author); revsets reading manifest deltas have weight 30 (ex. adds); revset reading manifest contents have weight 100 (ex. contains). Note: those values are flexible. If the revset has a same big-O time complexity as 'contains', but with a smaller constant, it might have a weight of 90. 'revsetpredicate' instance in example above can be used to decorate multiple functions. Decorated functions are registered automatically at loading extension, if an instance named as 'revsetpredicate' is used for decorating in extension. Otherwise, explicit 'revset.loadpredicate()' is needed. """ _getname = _funcregistrarbase._parsefuncdecl _docformat = "``%s``\n %s" def _extrasetup(self, name, func, safe=False, takeorder=False, weight=1): func._safe = safe func._takeorder = takeorder func._weight = weight class filesetpredicate(_funcregistrarbase): """Decorator to register fileset predicate Usage:: filesetpredicate = registrar.filesetpredicate() @filesetpredicate('mypredicate()') def mypredicatefunc(mctx, x): '''Explanation of this fileset predicate .... ''' pass The first string argument is used also in online help. Optional argument 'callstatus' indicates whether a predicate implies 'matchctx.status()' at runtime or not (False, by default). Optional argument 'weight' indicates the estimated run-time cost, useful for static optimization, default is 1. Higher weight means more expensive. There are predefined weights in the 'filesetlang' module. ====== ============================================================= Weight Description and examples ====== ============================================================= 0.5 basic match patterns (e.g. a symbol) 10 computing status (e.g. added()) or accessing a few files 30 reading file content for each (e.g. grep()) 50 scanning working directory (ignored()) ====== ============================================================= 'filesetpredicate' instance in example above can be used to decorate multiple functions. Decorated functions are registered automatically at loading extension, if an instance named as 'filesetpredicate' is used for decorating in extension. Otherwise, explicit 'fileset.loadpredicate()' is needed. """ _getname = _funcregistrarbase._parsefuncdecl _docformat = "``%s``\n %s" def _extrasetup(self, name, func, callstatus=False, weight=1): func._callstatus = callstatus func._weight = weight class _templateregistrarbase(_funcregistrarbase): """Base of decorator to register functions as template specific one """ _docformat = ":%s: %s" class templatekeyword(_templateregistrarbase): """Decorator to register template keyword Usage:: templatekeyword = registrar.templatekeyword() # new API (since Mercurial 4.6) @templatekeyword('mykeyword', requires={'repo', 'ctx'}) def mykeywordfunc(context, mapping): '''Explanation of this template keyword .... ''' pass # old API (DEPRECATED) @templatekeyword('mykeyword') def mykeywordfunc(repo, ctx, templ, cache, revcache, **args): '''Explanation of this template keyword .... ''' pass The first string argument is used also in online help. Optional argument 'requires' should be a collection of resource names which the template keyword depends on. This also serves as a flag to switch to the new API. If 'requires' is unspecified, all template keywords and resources are expanded to the function arguments. 'templatekeyword' instance in example above can be used to decorate multiple functions. Decorated functions are registered automatically at loading extension, if an instance named as 'templatekeyword' is used for decorating in extension. Otherwise, explicit 'templatekw.loadkeyword()' is needed. """ def _extrasetup(self, name, func, requires=None): func._requires = requires class templatefilter(_templateregistrarbase): """Decorator to register template filer Usage:: templatefilter = registrar.templatefilter() @templatefilter('myfilter', intype=bytes) def myfilterfunc(text): '''Explanation of this template filter .... ''' pass The first string argument is used also in online help. Optional argument 'intype' defines the type of the input argument, which should be (bytes, int, templateutil.date, or None for any.) 'templatefilter' instance in example above can be used to decorate multiple functions. Decorated functions are registered automatically at loading extension, if an instance named as 'templatefilter' is used for decorating in extension. Otherwise, explicit 'templatefilters.loadkeyword()' is needed. """ def _extrasetup(self, name, func, intype=None): func._intype = intype class templatefunc(_templateregistrarbase): """Decorator to register template function Usage:: templatefunc = registrar.templatefunc() @templatefunc('myfunc(arg1, arg2[, arg3])', argspec='arg1 arg2 arg3', requires={'ctx'}) def myfuncfunc(context, mapping, args): '''Explanation of this template function .... ''' pass The first string argument is used also in online help. If optional 'argspec' is defined, the function will receive 'args' as a dict of named arguments. Otherwise 'args' is a list of positional arguments. Optional argument 'requires' should be a collection of resource names which the template function depends on. 'templatefunc' instance in example above can be used to decorate multiple functions. Decorated functions are registered automatically at loading extension, if an instance named as 'templatefunc' is used for decorating in extension. Otherwise, explicit 'templatefuncs.loadfunction()' is needed. """ _getname = _funcregistrarbase._parsefuncdecl def _extrasetup(self, name, func, argspec=None, requires=()): func._argspec = argspec func._requires = requires class internalmerge(_funcregistrarbase): """Decorator to register in-process merge tool Usage:: internalmerge = registrar.internalmerge() @internalmerge('mymerge', internalmerge.mergeonly, onfailure=None, precheck=None, binary=False, symlink=False): def mymergefunc(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None): '''Explanation of this internal merge tool .... ''' return 1, False # means "conflicted", "no deletion needed" The first string argument is used to compose actual merge tool name, ":name" and "internal:name" (the latter is historical one). The second argument is one of merge types below: ========== ======== ======== ========= merge type precheck premerge fullmerge ========== ======== ======== ========= nomerge x x x mergeonly o x o fullmerge o o o ========== ======== ======== ========= Optional argument 'onfailure' is the format of warning message to be used at failure of merging (target filename is specified at formatting). Or, None or so, if warning message should be suppressed. Optional argument 'precheck' is the function to be used before actual invocation of internal merge tool itself. It takes as same arguments as internal merge tool does, other than 'files' and 'labels'. If it returns false value, merging is aborted immediately (and file is marked as "unresolved"). Optional argument 'binary' is a binary files capability of internal merge tool. 'nomerge' merge type implies binary=True. Optional argument 'symlink' is a symlinks capability of inetrnal merge function. 'nomerge' merge type implies symlink=True. 'internalmerge' instance in example above can be used to decorate multiple functions. Decorated functions are registered automatically at loading extension, if an instance named as 'internalmerge' is used for decorating in extension. Otherwise, explicit 'filemerge.loadinternalmerge()' is needed. """ _docformat = "``:%s``\n %s" # merge type definitions: nomerge = None mergeonly = 'mergeonly' # just the full merge, no premerge fullmerge = 'fullmerge' # both premerge and merge def _extrasetup(self, name, func, mergetype, onfailure=None, precheck=None, binary=False, symlink=False): func.mergetype = mergetype func.onfailure = onfailure func.precheck = precheck binarycap = binary or mergetype == self.nomerge symlinkcap = symlink or mergetype == self.nomerge # actual capabilities, which this internal merge tool has func.capabilities = {"binary": binarycap, "symlink": symlinkcap}