[PATCH 3 of 5 V2] manifest: introduce manifestlog and manifestctx classes

Martin von Zweigbergk martinvonz at google.com
Mon Aug 22 18:25:25 EDT 2016


On Mon, Aug 22, 2016 at 2:57 PM, Durham Goode <durham at fb.com> wrote:
>
>
> On 8/22/16 11:24 AM, Martin von Zweigbergk wrote:
>>
>> On Wed, Aug 17, 2016 at 2:07 PM, Durham Goode <durham at fb.com> wrote:
>>>
>>> # HG changeset patch
>>> # User Durham Goode <durham at fb.com>
>>> # Date 1471465513 25200
>>> #      Wed Aug 17 13:25:13 2016 -0700
>>> # Node ID 00f8d3832aad368660c69eff4be3e03a5568aebe
>>> # Parent  8ddbe86953023c40beb7be9dcb8025d1055813c5
>>> manifest: introduce manifestlog and manifestctx classes
>>>
>>> This is the start of a large refactoring of the manifest class. It
>>> introduces
>>> the new manifestlog and manifestctx classes which will represent the
>>> collection
>>> of all manifests and individual instances, respectively.
>>>
>>> Future patches will begin to convert usages of repo.manifest to
>>> repo.manifestlog, adding the necessary functionality to manifestlog and
>>> instance
>>> as they are needed.
>>
>> I'd appreciate seeing patch 5/5 squashed into this one. I don't like
>> introducing unused code like this without even tests (IIUC).
>>
>> And are we dropping 4/5? I'm not sure what the status of your
>> discussion with foozy is.
>
> I'd rather keep patch 4 until the fix lands in core, otherwise I'm not
> blocked on that diff.  If I squash 5/5 into this one, then I have to squash
> 4 in as well.  I can go ahead and do that, but that makes the patch a bit
> more dense.

Oh, I didn't even realize that 5/5 was blocked by 4/5, but that makes
sense now. I'll start tests now and queue this once they've finished.
Then foozy can decide whether to revert 4/5 later.

>
>>> diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
>>> --- a/mercurial/localrepo.py
>>> +++ b/mercurial/localrepo.py
>>> @@ -504,6 +504,10 @@ class localrepository(object):
>>>       def manifest(self):
>>>           return manifest.manifest(self.svfs)
>>>
>>> +    @storecache('00manifest.i')
>>> +    def manifestlog(self):
>>> +        return manifest.manifestlog(self.svfs, self.manifest)
>>> +
>>>       @repofilecache('dirstate')
>>>       def dirstate(self):
>>>           return dirstate.dirstate(self.vfs, self.ui, self.root,
>>> diff --git a/mercurial/manifest.py b/mercurial/manifest.py
>>> --- a/mercurial/manifest.py
>>> +++ b/mercurial/manifest.py
>>> @@ -914,6 +914,70 @@ class manifestrevlog(revlog.revlog):
>>>           super(manifestrevlog, self).clearcaches()
>>>           self._fulltextcache.clear()
>>>
>>> +class manifestlog(object):
>>> +    """A collection class representing the collection of manifest
>>> snapshots
>>> +    referenced by commits in the repository.
>>> +
>>> +    In this situation, 'manifest' refers to the abstract concept of a
>>> snapshot
>>> +    of the list of files in the given commit. Consumers of the output of
>>> this
>>> +    class do not care about the implementation details of the actual
>>> manifests
>>> +    they receive (i.e. tree or flat or lazily loaded, etc)."""
>>> +    def __init__(self, opener, oldmanifest):
>>> +        self._revlog = oldmanifest
>>> +
>>> +        # We'll separate this into it's own cache once oldmanifest is no
>>> longer
>>> +        # used
>>> +        self._mancache = oldmanifest._mancache
>>> +
>>> +        # _revlog is the same as _oldmanifest right now, but we
>>> eventually want
>>> +        # to delete _oldmanifest while still allowing manifestlog to
>>> access the
>>> +        # revlog specific apis.
>>> +        self._oldmanifest = oldmanifest
>>> +
>>> +    def __getitem__(self, node):
>>> +        """Retrieves the manifest instance for the given node. Throws a
>>> KeyError
>>> +        if not found.
>>> +        """
>>> +        if (self._oldmanifest._treeondisk
>>> +            or self._oldmanifest._treeinmem):
>>> +            # TODO: come back and support tree manifests directly
>>> +            return self._oldmanifest.read(node)
>>> +
>>> +        if node == revlog.nullid:
>>> +            return manifestdict()
>>> +        if node in self._mancache:
>>> +            cachemf = self._mancache[node]
>>> +            # The old manifest may put non-ctx manifests in the cache,
>>> so skip
>>> +            # those since they don't implement the full api.
>>> +            if isinstance(cachemf, manifestctx):
>>> +                return cachemf
>>> +
>>> +        m = manifestctx(self._revlog, node)
>>> +        self._mancache[node] = m
>>> +        return m
>>> +
>>> +class manifestctx(manifestdict):
>>> +    """A class representing a single revision of a manifest, including
>>> its
>>> +    contents, its parent revs, and its linkrev.
>>> +    """
>>> +    def __init__(self, revlog, node):
>>> +        self._revlog = revlog
>>> +
>>> +        self._node = node
>>> +        self.p1, self.p2 = revlog.parents(node)
>>> +        rev = revlog.rev(node)
>>> +        self.linkrev = revlog.linkrev(rev)
>>> +
>>> +        # This should eventually be made lazy loaded, so consumers can
>>> access
>>> +        # the node/p1/linkrev data without having to parse the whole
>>> manifest.
>>> +        data = revlog.revision(node)
>>> +        arraytext = array.array('c', data)
>>> +        revlog._fulltextcache[node] = arraytext
>>> +        super(manifestctx, self).__init__(data)
>>
>> I think much of this is not yet needed. The pedantic part of me wishes
>> it was left out until it is used, but I won't insist. I suppose it
>> serves as documentation of what future patches will add.
>
> The data stuff down here is required for instantiating the contents of the
> manifestdict.  The _node, p1, p2, linkrev stuff isn't used yet, sure, but
> that's the critical piece that differentiates this class from a
> manifestdict, and it's presence makes future patches clearer (like when we
> change the data to be lazily loaded, but node/p1/p2 are not).


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