indygreg created this revision. Herald added a subscriber: mercurial-devel. Herald added a reviewer: hg-reviewers.
REVISION SUMMARY In order to better support partial clones, we will need to overhaul local repository storage. This will be a major effort, as many parts of the code assume things like the existence of revlogs for storing data. To help support alternate storage implementations, we will create interfaces for accessing storage. The idea is that consumers will all code to an interface and any new interface-conforming implementation can come along and be swapped in to provide new and novel storage mechanisms. This commit starts the process of defining those interfaces. We define an interface for accessing files data. It has a single method for resolving the fulltext of an iterable of inputs. The interface is specifically defined to allow out-of-order responses. It also provides a mechanism for declaring that files data is censored. We *may* also want a mechanism to declare LFS or largefiles data. But I'm not sure how that mechanism works or what the best way to handle that would be, if any. We introduce a new "revlogstore" module to hold the definitions of these interfaces that use our existing revlog-based storage mechanism. An attribute pointing to the "files store" has been added to localrepository. No consumers of the new interface have been added. The interface should still be considered highly experimental and details are expected to change. It was tempting to define the interface as one level higher than file storage - in such a way to facilitate accessing changeset and manifest data as well. However, I believe these 3 primitives - changesets, manifests, and files - each have unique requirements that will dictate special, one-off methods on their storage interfaces. I'd rather we define our interfaces so they are tailored to each type initially. If an implementation wants to shoehorn all data into generic key-value blog store, they can still do that. And we also reserve the right to combine interfaces in the future. I just think that attempting to have the initial versions of the interfaces deviate too far from current reality will make it very challenging to define and implement them. The reason I'm defining and implementing this interface now is to support new (experimental) wire protocol commands to be used to support partial clone. Some of these commands will benefit from aggressive caching. I want to prove out the efficacy of the interfaces approach by implementing cache-based speedups in the interface layer. REPOSITORY rHG Mercurial REVISION DETAIL https://phab.mercurial-scm.org/D2883 AFFECTED FILES mercurial/localrepo.py mercurial/repository.py mercurial/revlogstore.py CHANGE DETAILS diff --git a/mercurial/revlogstore.py b/mercurial/revlogstore.py new file mode 100644 --- /dev/null +++ b/mercurial/revlogstore.py @@ -0,0 +1,37 @@ +# revlogstore.py - storage interface for repositories using revlog storage +# +# Copyright 2018 Gregory Szorc <gregory.sz...@gmail.com> +# +# 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 ( + error, + filelog, + repository, +) + +class revlogfilesstore(repository.basefilesstore): + """Files storage layer using revlogs for files storage.""" + + def __init__(self, svfs): + self._svfs = svfs + + def resolvefilesdata(self, entries): + for path, node in entries: + fl = filelog.filelog(self._svfs, path) + + try: + rev = fl.rev(node) + except error.LookupError: + yield 'missing', path, node, None + continue + + if fl.iscensored(rev): + yield 'censored', path, node, None + continue + + data = fl.read(node) + yield 'ok', path, node, data diff --git a/mercurial/repository.py b/mercurial/repository.py --- a/mercurial/repository.py +++ b/mercurial/repository.py @@ -266,3 +266,33 @@ class legacypeer(peer, _baselegacywirecommands): """peer but with support for legacy wire protocol commands.""" + +class basefilesstore(object): + """Storage interface for repository files data. + + This interface defines mechanisms to access repository files data in a + storage agnostic manner. The goal of this interface is to abstract storage + implementations so implementation details of storage don't leak into + higher-level repository consumers. + """ + + __metaclass__ = abc.ABCMeta + + def resolvefilesdata(self, entries): + """Resolve the fulltext data for an iterable of files. + + Each entry is defined by a 2-tuple of (path, node). + + The method is a generator that emits results as they become available. + Each emitted item is a 4-tuple of (result, path, node, data), where + the first element can be one of the following to represent the operation + result for this request: + + ok + Successfully resolved fulltext data. Data field is a bytes-like + object. + missing + Data for this item not found. Data field is ``None``. + censored + Data for this revision is censored. Data field is ``None``. + """ diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py --- a/mercurial/localrepo.py +++ b/mercurial/localrepo.py @@ -52,6 +52,7 @@ pycompat, repository, repoview, + revlogstore, revset, revsetlang, scmutil, @@ -479,6 +480,8 @@ else: # standard vfs self.svfs.audit = self._getsvfsward(self.svfs.audit) self._applyopenerreqs() + self.filesstore = revlogstore.revlogfilesstore(self.svfs) + if create: self._writerequirements() To: indygreg, #hg-reviewers Cc: mercurial-devel _______________________________________________ Mercurial-devel mailing list Mercurial-devel@mercurial-scm.org https://www.mercurial-scm.org/mailman/listinfo/mercurial-devel