hgext/remotefilelog/shallowbundle.py

rust: switch hg-core and hg-cpython to rust 2018 edition

Many interesting changes have happened in Rust since the Oxidation Plan was
introduced, like the 2018 edition and procedural macros:

    - Opting in to the 2018 edition is a clear benefit in terms of future
      proofing, new (nice to have) syntactical sugar notwithstanding. It
      also has a new non-lexical, non-AST based borrow checker that has
      fewer bugs(!) and allows us to write correct code that in some cases
      would have been rejected by the old one.
    - Procedural macros allow us to use the PyO3 crate which maintainers have
      expressed the clear goal of compiling on stable, which would help in
      code maintainability compared to rust-cpython.

In this patch are the following changes:
    - Removing most `extern crate` uses
    - Updating `use` clauses (`crate` keyword, nested `use`)
    - Removing `mod.rs` in favor of an aptly named module file

Like discussed in the mailing list (
https://www.mercurial-scm.org/pipermail/mercurial-devel/2019-July/132316.html
), until Rust integration in Mercurial is considered to be out of the
experimental phase, the maximum version of Rust allowed is whatever the latest
version Debian packages.

Differential Revision: https://phab.mercurial-scm.org/D6597

# shallowbundle.py - bundle10 implementation for use with shallow repositories
#
# Copyright 2013 Facebook, Inc.
#
# 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 mercurial.i18n import _
from mercurial.node import bin, hex, nullid
from mercurial import (
    bundlerepo,
    changegroup,
    error,
    match,
    mdiff,
    pycompat,
)
from . import (
    constants,
    remotefilelog,
    shallowutil,
)

NoFiles = 0
LocalFiles = 1
AllFiles = 2

def shallowgroup(cls, self, nodelist, rlog, lookup, units=None, reorder=None):
    if not isinstance(rlog, remotefilelog.remotefilelog):
        for c in super(cls, self).group(nodelist, rlog, lookup,
                                        units=units):
            yield c
        return

    if len(nodelist) == 0:
        yield self.close()
        return

    nodelist = shallowutil.sortnodes(nodelist, rlog.parents)

    # add the parent of the first rev
    p = rlog.parents(nodelist[0])[0]
    nodelist.insert(0, p)

    # build deltas
    for i in pycompat.xrange(len(nodelist) - 1):
        prev, curr = nodelist[i], nodelist[i + 1]
        linknode = lookup(curr)
        for c in self.nodechunk(rlog, curr, prev, linknode):
            yield c

    yield self.close()

class shallowcg1packer(changegroup.cgpacker):
    def generate(self, commonrevs, clnodes, fastpathlinkrev, source):
        if shallowutil.isenabled(self._repo):
            fastpathlinkrev = False

        return super(shallowcg1packer, self).generate(commonrevs, clnodes,
            fastpathlinkrev, source)

    def group(self, nodelist, rlog, lookup, units=None, reorder=None):
        return shallowgroup(shallowcg1packer, self, nodelist, rlog, lookup,
                            units=units)

    def generatefiles(self, changedfiles, *args):
        try:
            linknodes, commonrevs, source = args
        except ValueError:
            commonrevs, source, mfdicts, fastpathlinkrev, fnodes, clrevs = args
        if shallowutil.isenabled(self._repo):
            repo = self._repo
            if isinstance(repo, bundlerepo.bundlerepository):
                # If the bundle contains filelogs, we can't pull from it, since
                # bundlerepo is heavily tied to revlogs. Instead require that
                # the user use unbundle instead.
                # Force load the filelog data.
                bundlerepo.bundlerepository.file(repo, 'foo')
                if repo._cgfilespos:
                    raise error.Abort("cannot pull from full bundles",
                                      hint="use `hg unbundle` instead")
                return []
            filestosend = self.shouldaddfilegroups(source)
            if filestosend == NoFiles:
                changedfiles = list([f for f in changedfiles
                                     if not repo.shallowmatch(f)])

        return super(shallowcg1packer, self).generatefiles(
            changedfiles, *args)

    def shouldaddfilegroups(self, source):
        repo = self._repo
        if not shallowutil.isenabled(repo):
            return AllFiles

        if source == "push" or source == "bundle":
            return AllFiles

        caps = self._bundlecaps or []
        if source == "serve" or source == "pull":
            if constants.BUNDLE2_CAPABLITY in caps:
                return LocalFiles
            else:
                # Serving to a full repo requires us to serve everything
                repo.ui.warn(_("pulling from a shallow repo\n"))
                return AllFiles

        return NoFiles

    def prune(self, rlog, missing, commonrevs):
        if not isinstance(rlog, remotefilelog.remotefilelog):
            return super(shallowcg1packer, self).prune(rlog, missing,
                commonrevs)

        repo = self._repo
        results = []
        for fnode in missing:
            fctx = repo.filectx(rlog.filename, fileid=fnode)
            if fctx.linkrev() not in commonrevs:
                results.append(fnode)
        return results

    def nodechunk(self, revlog, node, prevnode, linknode):
        prefix = ''
        if prevnode == nullid:
            delta = revlog.revision(node, raw=True)
            prefix = mdiff.trivialdiffheader(len(delta))
        else:
            # Actually uses remotefilelog.revdiff which works on nodes, not revs
            delta = revlog.revdiff(prevnode, node)
        p1, p2 = revlog.parents(node)
        flags = revlog.flags(node)
        meta = self.builddeltaheader(node, p1, p2, prevnode, linknode, flags)
        meta += prefix
        l = len(meta) + len(delta)
        yield changegroup.chunkheader(l)
        yield meta
        yield delta

def makechangegroup(orig, repo, outgoing, version, source, *args, **kwargs):
    if not shallowutil.isenabled(repo):
        return orig(repo, outgoing, version, source, *args, **kwargs)

    original = repo.shallowmatch
    try:
        # if serving, only send files the clients has patterns for
        if source == 'serve':
            bundlecaps = kwargs.get(r'bundlecaps')
            includepattern = None
            excludepattern = None
            for cap in (bundlecaps or []):
                if cap.startswith("includepattern="):
                    raw = cap[len("includepattern="):]
                    if raw:
                        includepattern = raw.split('\0')
                elif cap.startswith("excludepattern="):
                    raw = cap[len("excludepattern="):]
                    if raw:
                        excludepattern = raw.split('\0')
            if includepattern or excludepattern:
                repo.shallowmatch = match.match(repo.root, '', None,
                    includepattern, excludepattern)
            else:
                repo.shallowmatch = match.always()
        return orig(repo, outgoing, version, source, *args, **kwargs)
    finally:
        repo.shallowmatch = original

def addchangegroupfiles(orig, repo, source, revmap, trp, expectedfiles, *args):
    if not shallowutil.isenabled(repo):
        return orig(repo, source, revmap, trp, expectedfiles, *args)

    newfiles = 0
    visited = set()
    revisiondatas = {}
    queue = []

    # Normal Mercurial processes each file one at a time, adding all
    # the new revisions for that file at once. In remotefilelog a file
    # revision may depend on a different file's revision (in the case
    # of a rename/copy), so we must lay all revisions down across all
    # files in topological order.

    # read all the file chunks but don't add them
    progress = repo.ui.makeprogress(_('files'), total=expectedfiles)
    while True:
        chunkdata = source.filelogheader()
        if not chunkdata:
            break
        f = chunkdata["filename"]
        repo.ui.debug("adding %s revisions\n" % f)
        progress.increment()

        if not repo.shallowmatch(f):
            fl = repo.file(f)
            deltas = source.deltaiter()
            fl.addgroup(deltas, revmap, trp)
            continue

        chain = None
        while True:
            # returns: (node, p1, p2, cs, deltabase, delta, flags) or None
            revisiondata = source.deltachunk(chain)
            if not revisiondata:
                break

            chain = revisiondata[0]

            revisiondatas[(f, chain)] = revisiondata
            queue.append((f, chain))

            if f not in visited:
                newfiles += 1
                visited.add(f)

        if chain is None:
            raise error.Abort(_("received file revlog group is empty"))

    processed = set()
    def available(f, node, depf, depnode):
        if depnode != nullid and (depf, depnode) not in processed:
            if not (depf, depnode) in revisiondatas:
                # It's not in the changegroup, assume it's already
                # in the repo
                return True
            # re-add self to queue
            queue.insert(0, (f, node))
            # add dependency in front
            queue.insert(0, (depf, depnode))
            return False
        return True

    skipcount = 0

    # Prefetch the non-bundled revisions that we will need
    prefetchfiles = []
    for f, node in queue:
        revisiondata = revisiondatas[(f, node)]
        # revisiondata: (node, p1, p2, cs, deltabase, delta, flags)
        dependents = [revisiondata[1], revisiondata[2], revisiondata[4]]

        for dependent in dependents:
            if dependent == nullid or (f, dependent) in revisiondatas:
                continue
            prefetchfiles.append((f, hex(dependent)))

    repo.fileservice.prefetch(prefetchfiles)

    # Apply the revisions in topological order such that a revision
    # is only written once it's deltabase and parents have been written.
    while queue:
        f, node = queue.pop(0)
        if (f, node) in processed:
            continue

        skipcount += 1
        if skipcount > len(queue) + 1:
            raise error.Abort(_("circular node dependency"))

        fl = repo.file(f)

        revisiondata = revisiondatas[(f, node)]
        # revisiondata: (node, p1, p2, cs, deltabase, delta, flags)
        node, p1, p2, linknode, deltabase, delta, flags = revisiondata

        if not available(f, node, f, deltabase):
            continue

        base = fl.revision(deltabase, raw=True)
        text = mdiff.patch(base, delta)
        if not isinstance(text, bytes):
            text = bytes(text)

        meta, text = shallowutil.parsemeta(text)
        if 'copy' in meta:
            copyfrom = meta['copy']
            copynode = bin(meta['copyrev'])
            if not available(f, node, copyfrom, copynode):
                continue

        for p in [p1, p2]:
            if p != nullid:
                if not available(f, node, f, p):
                    continue

        fl.add(text, meta, trp, linknode, p1, p2)
        processed.add((f, node))
        skipcount = 0

    progress.complete()

    return len(revisiondatas), newfiles