Mercurial > hg
view mercurial/upgrade_utils/actions.py @ 46052:08802795ae90
upgrade: gather code about requirement checking together
They just moved in the same file, now they are grouped together and documented.
Differential Revision: https://phab.mercurial-scm.org/D9486
author | Pierre-Yves David <pierre-yves.david@octobus.net> |
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date | Tue, 01 Dec 2020 20:35:19 +0100 |
parents | 72b7b4bf3e65 |
children | c407513a44a3 |
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# upgrade.py - functions for in place upgrade of Mercurial repository # # Copyright (c) 2016-present, Gregory Szorc # # 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 ..i18n import _ from .. import ( error, localrepo, requirements, util, ) from ..utils import compression # list of requirements that request a clone of all revlog if added/removed RECLONES_REQUIREMENTS = { b'generaldelta', requirements.SPARSEREVLOG_REQUIREMENT, } def preservedrequirements(repo): return set() DEFICIENCY = b'deficiency' OPTIMISATION = b'optimization' class improvement(object): """Represents an improvement that can be made as part of an upgrade. The following attributes are defined on each instance: name Machine-readable string uniquely identifying this improvement. It will be mapped to an action later in the upgrade process. type Either ``DEFICIENCY`` or ``OPTIMISATION``. A deficiency is an obvious problem. An optimization is an action (sometimes optional) that can be taken to further improve the state of the repository. description Message intended for humans explaining the improvement in more detail, including the implications of it. For ``DEFICIENCY`` types, should be worded in the present tense. For ``OPTIMISATION`` types, should be worded in the future tense. upgrademessage Message intended for humans explaining what an upgrade addressing this issue will do. Should be worded in the future tense. """ def __init__(self, name, type, description, upgrademessage): self.name = name self.type = type self.description = description self.upgrademessage = upgrademessage def __eq__(self, other): if not isinstance(other, improvement): # This is what python tell use to do return NotImplemented return self.name == other.name def __ne__(self, other): return not (self == other) def __hash__(self): return hash(self.name) allformatvariant = [] def registerformatvariant(cls): allformatvariant.append(cls) return cls class formatvariant(improvement): """an improvement subclass dedicated to repository format""" type = DEFICIENCY ### The following attributes should be defined for each class: # machine-readable string uniquely identifying this improvement. it will be # mapped to an action later in the upgrade process. name = None # message intended for humans explaining the improvement in more detail, # including the implications of it ``DEFICIENCY`` types, should be worded # in the present tense. description = None # message intended for humans explaining what an upgrade addressing this # issue will do. should be worded in the future tense. upgrademessage = None # value of current Mercurial default for new repository default = None def __init__(self): raise NotImplementedError() @staticmethod def fromrepo(repo): """current value of the variant in the repository""" raise NotImplementedError() @staticmethod def fromconfig(repo): """current value of the variant in the configuration""" raise NotImplementedError() class requirementformatvariant(formatvariant): """formatvariant based on a 'requirement' name. Many format variant are controlled by a 'requirement'. We define a small subclass to factor the code. """ # the requirement that control this format variant _requirement = None @staticmethod def _newreporequirements(ui): return localrepo.newreporequirements( ui, localrepo.defaultcreateopts(ui) ) @classmethod def fromrepo(cls, repo): assert cls._requirement is not None return cls._requirement in repo.requirements @classmethod def fromconfig(cls, repo): assert cls._requirement is not None return cls._requirement in cls._newreporequirements(repo.ui) @registerformatvariant class fncache(requirementformatvariant): name = b'fncache' _requirement = b'fncache' default = True description = _( b'long and reserved filenames may not work correctly; ' b'repository performance is sub-optimal' ) upgrademessage = _( b'repository will be more resilient to storing ' b'certain paths and performance of certain ' b'operations should be improved' ) @registerformatvariant class dotencode(requirementformatvariant): name = b'dotencode' _requirement = b'dotencode' default = True description = _( b'storage of filenames beginning with a period or ' b'space may not work correctly' ) upgrademessage = _( b'repository will be better able to store files ' b'beginning with a space or period' ) @registerformatvariant class generaldelta(requirementformatvariant): name = b'generaldelta' _requirement = b'generaldelta' default = True description = _( b'deltas within internal storage are unable to ' b'choose optimal revisions; repository is larger and ' b'slower than it could be; interaction with other ' b'repositories may require extra network and CPU ' b'resources, making "hg push" and "hg pull" slower' ) upgrademessage = _( b'repository storage will be able to create ' b'optimal deltas; new repository data will be ' b'smaller and read times should decrease; ' b'interacting with other repositories using this ' b'storage model should require less network and ' b'CPU resources, making "hg push" and "hg pull" ' b'faster' ) @registerformatvariant class sharesafe(requirementformatvariant): name = b'exp-sharesafe' _requirement = requirements.SHARESAFE_REQUIREMENT default = False description = _( b'old shared repositories do not share source repository ' b'requirements and config. This leads to various problems ' b'when the source repository format is upgraded or some new ' b'extensions are enabled.' ) upgrademessage = _( b'Upgrades a repository to share-safe format so that future ' b'shares of this repository share its requirements and configs.' ) @registerformatvariant class sparserevlog(requirementformatvariant): name = b'sparserevlog' _requirement = requirements.SPARSEREVLOG_REQUIREMENT default = True description = _( b'in order to limit disk reading and memory usage on older ' b'version, the span of a delta chain from its root to its ' b'end is limited, whatever the relevant data in this span. ' b'This can severly limit Mercurial ability to build good ' b'chain of delta resulting is much more storage space being ' b'taken and limit reusability of on disk delta during ' b'exchange.' ) upgrademessage = _( b'Revlog supports delta chain with more unused data ' b'between payload. These gaps will be skipped at read ' b'time. This allows for better delta chains, making a ' b'better compression and faster exchange with server.' ) @registerformatvariant class sidedata(requirementformatvariant): name = b'sidedata' _requirement = requirements.SIDEDATA_REQUIREMENT default = False description = _( b'Allows storage of extra data alongside a revision, ' b'unlocking various caching options.' ) upgrademessage = _(b'Allows storage of extra data alongside a revision.') @registerformatvariant class persistentnodemap(requirementformatvariant): name = b'persistent-nodemap' _requirement = requirements.NODEMAP_REQUIREMENT default = False description = _( b'persist the node -> rev mapping on disk to speedup lookup' ) upgrademessage = _(b'Speedup revision lookup by node id.') @registerformatvariant class copiessdc(requirementformatvariant): name = b'copies-sdc' _requirement = requirements.COPIESSDC_REQUIREMENT default = False description = _(b'Stores copies information alongside changesets.') upgrademessage = _( b'Allows to use more efficient algorithm to deal with ' b'copy tracing.' ) @registerformatvariant class removecldeltachain(formatvariant): name = b'plain-cl-delta' default = True description = _( b'changelog storage is using deltas instead of ' b'raw entries; changelog reading and any ' b'operation relying on changelog data are slower ' b'than they could be' ) upgrademessage = _( b'changelog storage will be reformated to ' b'store raw entries; changelog reading will be ' b'faster; changelog size may be reduced' ) @staticmethod def fromrepo(repo): # Mercurial 4.0 changed changelogs to not use delta chains. Search for # changelogs with deltas. cl = repo.changelog chainbase = cl.chainbase return all(rev == chainbase(rev) for rev in cl) @staticmethod def fromconfig(repo): return True @registerformatvariant class compressionengine(formatvariant): name = b'compression' default = b'zlib' description = _( b'Compresion algorithm used to compress data. ' b'Some engine are faster than other' ) upgrademessage = _( b'revlog content will be recompressed with the new algorithm.' ) @classmethod def fromrepo(cls, repo): # we allow multiple compression engine requirement to co-exist because # strickly speaking, revlog seems to support mixed compression style. # # The compression used for new entries will be "the last one" compression = b'zlib' for req in repo.requirements: prefix = req.startswith if prefix(b'revlog-compression-') or prefix(b'exp-compression-'): compression = req.split(b'-', 2)[2] return compression @classmethod def fromconfig(cls, repo): compengines = repo.ui.configlist(b'format', b'revlog-compression') # return the first valid value as the selection code would do for comp in compengines: if comp in util.compengines: return comp # no valide compression found lets display it all for clarity return b','.join(compengines) @registerformatvariant class compressionlevel(formatvariant): name = b'compression-level' default = b'default' description = _(b'compression level') upgrademessage = _(b'revlog content will be recompressed') @classmethod def fromrepo(cls, repo): comp = compressionengine.fromrepo(repo) level = None if comp == b'zlib': level = repo.ui.configint(b'storage', b'revlog.zlib.level') elif comp == b'zstd': level = repo.ui.configint(b'storage', b'revlog.zstd.level') if level is None: return b'default' return bytes(level) @classmethod def fromconfig(cls, repo): comp = compressionengine.fromconfig(repo) level = None if comp == b'zlib': level = repo.ui.configint(b'storage', b'revlog.zlib.level') elif comp == b'zstd': level = repo.ui.configint(b'storage', b'revlog.zstd.level') if level is None: return b'default' return bytes(level) def finddeficiencies(repo): """returns a list of deficiencies that the repo suffer from""" deficiencies = [] # We could detect lack of revlogv1 and store here, but they were added # in 0.9.2 and we don't support upgrading repos without these # requirements, so let's not bother. for fv in allformatvariant: if not fv.fromrepo(repo): deficiencies.append(fv) return deficiencies ALL_OPTIMISATIONS = [] def register_optimization(obj): ALL_OPTIMISATIONS.append(obj) return obj register_optimization( improvement( name=b're-delta-parent', type=OPTIMISATION, description=_( b'deltas within internal storage will be recalculated to ' b'choose an optimal base revision where this was not ' b'already done; the size of the repository may shrink and ' b'various operations may become faster; the first time ' b'this optimization is performed could slow down upgrade ' b'execution considerably; subsequent invocations should ' b'not run noticeably slower' ), upgrademessage=_( b'deltas within internal storage will choose a new ' b'base revision if needed' ), ) ) register_optimization( improvement( name=b're-delta-multibase', type=OPTIMISATION, description=_( b'deltas within internal storage will be recalculated ' b'against multiple base revision and the smallest ' b'difference will be used; the size of the repository may ' b'shrink significantly when there are many merges; this ' b'optimization will slow down execution in proportion to ' b'the number of merges in the repository and the amount ' b'of files in the repository; this slow down should not ' b'be significant unless there are tens of thousands of ' b'files and thousands of merges' ), upgrademessage=_( b'deltas within internal storage will choose an ' b'optimal delta by computing deltas against multiple ' b'parents; may slow down execution time ' b'significantly' ), ) ) register_optimization( improvement( name=b're-delta-all', type=OPTIMISATION, description=_( b'deltas within internal storage will always be ' b'recalculated without reusing prior deltas; this will ' b'likely make execution run several times slower; this ' b'optimization is typically not needed' ), upgrademessage=_( b'deltas within internal storage will be fully ' b'recomputed; this will likely drastically slow down ' b'execution time' ), ) ) register_optimization( improvement( name=b're-delta-fulladd', type=OPTIMISATION, description=_( b'every revision will be re-added as if it was new ' b'content. It will go through the full storage ' b'mechanism giving extensions a chance to process it ' b'(eg. lfs). This is similar to "re-delta-all" but even ' b'slower since more logic is involved.' ), upgrademessage=_( b'each revision will be added as new content to the ' b'internal storage; this will likely drastically slow ' b'down execution time, but some extensions might need ' b'it' ), ) ) def findoptimizations(repo): """Determine optimisation that could be used during upgrade""" # These are unconditionally added. There is logic later that figures out # which ones to apply. return list(ALL_OPTIMISATIONS) def determineactions(repo, deficiencies, sourcereqs, destreqs): """Determine upgrade actions that will be performed. Given a list of improvements as returned by ``finddeficiencies`` and ``findoptimizations``, determine the list of upgrade actions that will be performed. The role of this function is to filter improvements if needed, apply recommended optimizations from the improvements list that make sense, etc. Returns a list of action names. """ newactions = [] for d in deficiencies: name = d._requirement # If the action is a requirement that doesn't show up in the # destination requirements, prune the action. if name is not None and name not in destreqs: continue newactions.append(d) # FUTURE consider adding some optimizations here for certain transitions. # e.g. adding generaldelta could schedule parent redeltas. return newactions ### Code checking if a repository can got through the upgrade process at all. # def requiredsourcerequirements(repo): """Obtain requirements required to be present to upgrade a repo. An upgrade will not be allowed if the repository doesn't have the requirements returned by this function. """ return { # Introduced in Mercurial 0.9.2. b'revlogv1', # Introduced in Mercurial 0.9.2. b'store', } def blocksourcerequirements(repo): """Obtain requirements that will prevent an upgrade from occurring. An upgrade cannot be performed if the source repository contains a requirements in the returned set. """ return { # The upgrade code does not yet support these experimental features. # This is an artificial limitation. requirements.TREEMANIFEST_REQUIREMENT, # This was a precursor to generaldelta and was never enabled by default. # It should (hopefully) not exist in the wild. b'parentdelta', # Upgrade should operate on the actual store, not the shared link. requirements.SHARED_REQUIREMENT, } def check_source_requirements(repo): """Ensure that no existing requirements prevent the repository upgrade""" required = requiredsourcerequirements(repo) missingreqs = required - repo.requirements if missingreqs: msg = _(b'cannot upgrade repository; requirement missing: %s') missingreqs = b', '.join(sorted(missingreqs)) raise error.Abort(msg % missingreqs) blocking = blocksourcerequirements(repo) blockingreqs = blocking & repo.requirements if blockingreqs: m = _(b'cannot upgrade repository; unsupported source requirement: %s') blockingreqs = b', '.join(sorted(blockingreqs)) raise error.Abort(m % blockingreqs) ### Verify the validity of the planned requirement changes #################### def supportremovedrequirements(repo): """Obtain requirements that can be removed during an upgrade. If an upgrade were to create a repository that dropped a requirement, the dropped requirement must appear in the returned set for the upgrade to be allowed. """ supported = { requirements.SPARSEREVLOG_REQUIREMENT, requirements.SIDEDATA_REQUIREMENT, requirements.COPIESSDC_REQUIREMENT, requirements.NODEMAP_REQUIREMENT, requirements.SHARESAFE_REQUIREMENT, } for name in compression.compengines: engine = compression.compengines[name] if engine.available() and engine.revlogheader(): supported.add(b'exp-compression-%s' % name) if engine.name() == b'zstd': supported.add(b'revlog-compression-zstd') return supported def supporteddestrequirements(repo): """Obtain requirements that upgrade supports in the destination. If the result of the upgrade would create requirements not in this set, the upgrade is disallowed. Extensions should monkeypatch this to add their custom requirements. """ supported = { b'dotencode', b'fncache', b'generaldelta', b'revlogv1', b'store', requirements.SPARSEREVLOG_REQUIREMENT, requirements.SIDEDATA_REQUIREMENT, requirements.COPIESSDC_REQUIREMENT, requirements.NODEMAP_REQUIREMENT, requirements.SHARESAFE_REQUIREMENT, } for name in compression.compengines: engine = compression.compengines[name] if engine.available() and engine.revlogheader(): supported.add(b'exp-compression-%s' % name) if engine.name() == b'zstd': supported.add(b'revlog-compression-zstd') return supported def allowednewrequirements(repo): """Obtain requirements that can be added to a repository during upgrade. This is used to disallow proposed requirements from being added when they weren't present before. We use a list of allowed requirement additions instead of a list of known bad additions because the whitelist approach is safer and will prevent future, unknown requirements from accidentally being added. """ supported = { b'dotencode', b'fncache', b'generaldelta', requirements.SPARSEREVLOG_REQUIREMENT, requirements.SIDEDATA_REQUIREMENT, requirements.COPIESSDC_REQUIREMENT, requirements.NODEMAP_REQUIREMENT, requirements.SHARESAFE_REQUIREMENT, } for name in compression.compengines: engine = compression.compengines[name] if engine.available() and engine.revlogheader(): supported.add(b'exp-compression-%s' % name) if engine.name() == b'zstd': supported.add(b'revlog-compression-zstd') return supported def check_requirements_changes(repo, new_reqs): old_reqs = repo.requirements support_removal = supportremovedrequirements(repo) no_remove_reqs = old_reqs - new_reqs - support_removal if no_remove_reqs: msg = _(b'cannot upgrade repository; requirement would be removed: %s') no_remove_reqs = b', '.join(sorted(no_remove_reqs)) raise error.Abort(msg % no_remove_reqs) support_addition = allowednewrequirements(repo) no_add_reqs = new_reqs - old_reqs - support_addition if no_add_reqs: m = _(b'cannot upgrade repository; do not support adding requirement: ') no_add_reqs = b', '.join(sorted(no_add_reqs)) raise error.Abort(m + no_add_reqs) supported = supporteddestrequirements(repo) unsupported_reqs = new_reqs - supported if unsupported_reqs: msg = _( b'cannot upgrade repository; do not support destination ' b'requirement: %s' ) unsupported_reqs = b', '.join(sorted(unsupported_reqs)) raise error.Abort(msg % unsupported_reqs)