rust: module policy with importrust
We introduce two rust+c module policies and a new
`policy.importrust()` that makes use of them.
This simple approach provides runtime switching of
implementations, which is crucial for the performance
measurements such as those Octobus does with ASV.
It can also be useful for bug analysis.
It also has the advantage of making conditionals in
Rust callers more uniform, in particular
abstracting over specifics like `demandimport`
At this point, the build stays unchanged, with the rust-cpython based
`rustext` module being built if HGWITHRUSTEXT=cpython.
More transparency for the callers, i.e., just using
`policy.importmod` would be a much longer term and riskier
effort for the following reasons:
1. It would require to define common module boundaries
for the three or four cases (pure, c, rust+ext, cffi) and that
is premature with the Rust extension currently under heavy
development in areas that are outside the scope of the C extensions.
2. It would imply internal API changes that are not currently wished,
as the case of ancestors demonstrates.
3. The lack of data or property-like attributes (tp_member
and tp_getset) in current `rust-cpython` makes it impossible to
achieve direct transparent replacement of pure Python classes by
Rust extension code, meaning that the caller sometimes has to be able
to make adjustments or provide additional wrapping.
from __future__ import absolute_import
from .i18n import _
from . import (
registrar,
templatekw,
util,
)
def tolist(val):
"""
a convenience method to return an empty list instead of None
"""
if val is None:
return []
else:
return [val]
class namespaces(object):
"""provides an interface to register and operate on multiple namespaces. See
the namespace class below for details on the namespace object.
"""
_names_version = 0
def __init__(self):
self._names = util.sortdict()
columns = templatekw.getlogcolumns()
# we need current mercurial named objects (bookmarks, tags, and
# branches) to be initialized somewhere, so that place is here
bmknames = lambda repo: repo._bookmarks.keys()
bmknamemap = lambda repo, name: tolist(repo._bookmarks.get(name))
bmknodemap = lambda repo, node: repo.nodebookmarks(node)
n = namespace("bookmarks", templatename="bookmark",
logfmt=columns['bookmark'],
listnames=bmknames,
namemap=bmknamemap, nodemap=bmknodemap,
builtin=True)
self.addnamespace(n)
tagnames = lambda repo: [t for t, n in repo.tagslist()]
tagnamemap = lambda repo, name: tolist(repo._tagscache.tags.get(name))
tagnodemap = lambda repo, node: repo.nodetags(node)
n = namespace("tags", templatename="tag",
logfmt=columns['tag'],
listnames=tagnames,
namemap=tagnamemap, nodemap=tagnodemap,
deprecated={'tip'},
builtin=True)
self.addnamespace(n)
bnames = lambda repo: repo.branchmap().keys()
bnamemap = lambda repo, name: tolist(repo.branchtip(name, True))
bnodemap = lambda repo, node: [repo[node].branch()]
n = namespace("branches", templatename="branch",
logfmt=columns['branch'],
listnames=bnames,
namemap=bnamemap, nodemap=bnodemap,
builtin=True)
self.addnamespace(n)
def __getitem__(self, namespace):
"""returns the namespace object"""
return self._names[namespace]
def __iter__(self):
return self._names.__iter__()
def items(self):
return self._names.iteritems()
iteritems = items
def addnamespace(self, namespace, order=None):
"""register a namespace
namespace: the name to be registered (in plural form)
order: optional argument to specify the order of namespaces
(e.g. 'branches' should be listed before 'bookmarks')
"""
if order is not None:
self._names.insert(order, namespace.name, namespace)
else:
self._names[namespace.name] = namespace
# we only generate a template keyword if one does not already exist
if namespace.name not in templatekw.keywords:
templatekeyword = registrar.templatekeyword(templatekw.keywords)
@templatekeyword(namespace.name, requires={'repo', 'ctx'})
def generatekw(context, mapping):
return templatekw.shownames(context, mapping, namespace.name)
def singlenode(self, repo, name):
"""
Return the 'best' node for the given name. What's best is defined
by the namespace's singlenode() function. The first match returned by
a namespace in the defined precedence order is used.
Raises a KeyError if there is no such node.
"""
for ns, v in self._names.iteritems():
n = v.singlenode(repo, name)
if n:
return n
raise KeyError(_('no such name: %s') % name)
class namespace(object):
"""provides an interface to a namespace
Namespaces are basically generic many-to-many mapping between some
(namespaced) names and nodes. The goal here is to control the pollution of
jamming things into tags or bookmarks (in extension-land) and to simplify
internal bits of mercurial: log output, tab completion, etc.
More precisely, we define a mapping of names to nodes, and a mapping from
nodes to names. Each mapping returns a list.
Furthermore, each name mapping will be passed a name to lookup which might
not be in its domain. In this case, each method should return an empty list
and not raise an error.
This namespace object will define the properties we need:
'name': the namespace (plural form)
'templatename': name to use for templating (usually the singular form
of the plural namespace name)
'listnames': list of all names in the namespace (usually the keys of a
dictionary)
'namemap': function that takes a name and returns a list of nodes
'nodemap': function that takes a node and returns a list of names
'deprecated': set of names to be masked for ordinary use
'builtin': bool indicating if this namespace is supported by core
Mercurial.
"""
def __init__(self, name, templatename=None, logname=None, colorname=None,
logfmt=None, listnames=None, namemap=None, nodemap=None,
deprecated=None, builtin=False, singlenode=None):
"""create a namespace
name: the namespace to be registered (in plural form)
templatename: the name to use for templating
logname: the name to use for log output; if not specified templatename
is used
colorname: the name to use for colored log output; if not specified
logname is used
logfmt: the format to use for (i18n-ed) log output; if not specified
it is composed from logname
listnames: function to list all names
namemap: function that inputs a name, output node(s)
nodemap: function that inputs a node, output name(s)
deprecated: set of names to be masked for ordinary use
builtin: whether namespace is implemented by core Mercurial
singlenode: function that inputs a name, output best node (or None)
"""
self.name = name
self.templatename = templatename
self.logname = logname
self.colorname = colorname
self.logfmt = logfmt
self.listnames = listnames
self.namemap = namemap
self.nodemap = nodemap
if singlenode:
self.singlenode = singlenode
# if logname is not specified, use the template name as backup
if self.logname is None:
self.logname = self.templatename
# if colorname is not specified, just use the logname as a backup
if self.colorname is None:
self.colorname = self.logname
# if logfmt is not specified, compose it from logname as backup
if self.logfmt is None:
# i18n: column positioning for "hg log"
self.logfmt = ("%s:" % self.logname).ljust(13) + "%s\n"
if deprecated is None:
self.deprecated = set()
else:
self.deprecated = deprecated
self.builtin = builtin
def names(self, repo, node):
"""method that returns a (sorted) list of names in a namespace that
match a given node"""
return sorted(self.nodemap(repo, node))
def nodes(self, repo, name):
"""method that returns a list of nodes in a namespace that
match a given name.
"""
return sorted(self.namemap(repo, name))
def singlenode(self, repo, name):
"""returns the best node for the given name
By default, the best node is the node from nodes() with the highest
revision number. It can be overriden by the namespace."""
n = self.namemap(repo, name)
if n:
# return max revision number
if len(n) > 1:
cl = repo.changelog
maxrev = max(cl.rev(node) for node in n)
return cl.node(maxrev)
return n[0]
return None