view mercurial/bundlecaches.py @ 48687:f8f2ecdde4b5

branchmap: skip obsolete revisions while computing heads

It's time to make this part of core Mercurial obsolescence-aware.

Not considering obsolete revisions when computing heads is clearly what
Mercurial should do. But there are a couple of small issues:

- Let's say tip of the repo is obsolete. There are two ways of finding tiprev
  for branchcache (both are in use): looking at input data for update() and
  looking at computed heads after update(). Previously, repo tip would be
  tiprev of the branchcache. With this patch, an obsolete revision can no
  longer be tiprev. And depending on what way we use for finding tiprev (input
  data vs computed heads) we'll get a different result. This is relevant when
  recomputing cache key from cache contents, and may lead to updating cache for
  obsolete revisions multiple times (not from scratch, because it still would
  be considered valid for a subset of revisions in the repo).

- If all commits on a branch are obsolete, the branchcache will include that
  branch, but the list of heads will be empty (that's why there's now `if not
  heads` when recomputing tiprev/tipnode from cache contents). Having an entry
  for every branch is currently required for notify extension (and
  test-notify.t to pass), because notify doesn't handle revsets in its
  subscription config very well and will throw an error if e.g. a branch
  doesn't exist.

- Cloning static HTTP repos may try to stat() a non-existent obsstore file. The
  issue is that we now care about obsolescence during clone, but statichttpvfs
  doesn't implement a stat method, so a regular vfs.stat() is used, and it
  assumes that file is local and calls os.stat().  During a clone, we're trying
  to stat() .hg/store/obsstore, but in static HTTP case we provide a literal
  URL to the obsstore file on the remote as if it were a local file path. On
  windows it actually results in a failure in test-static-http.t.

The first issue is going to be addressed in a series dedicated to making sure
branchcache is properly and timely written on disk (it wasn't perfect even
before this patch, but there aren't enough tests to demonstrate that). The
second issue will be addressed in a future patch for notify extension that will
make it not raise an exception if a branch doesn't exist. And the third one was
partially addressed in the previous patch in this series and will be properly
fixed in a future patch when this series is accepted.

filteredhash() grows a keyword argument to make sure that branchcache is also
invalidated when there are new obsolete revisions in its repo view. This way
the on-disk cache format is unchanged and compatible between versions (although
it will obviously be recomputed when switching versions before/after this patch
and the repo has obsolete revisions).

There's one test that uses plain `hg up` without arguments while updated to a
pruned commit. To make this test pass, simply return current working directory
parent. Later in this series this code will be replaced by what prune command
does: updating to the closest non-obsolete ancestor.

Test changes:

test-branch-change.t: update branch head and cache update message. The head of
default listed in hg heads is changed because revision 2 was rewritten as 7,
and 1 is the closest ancestor on the same branch, so it's the head of default
now.

The cache invalidation message appears now because of the cache hash change,
since we're now accounting for obsolete revisions. Here's some context:

"served.hidden" repo filter means everything is visible (no filtered
revisions), so before this series branch2-served.hidden file would not contain
any cache hash, only revnum and node. Now it also has a hash when there are
obsolete changesets in the repo. The command that the message appears for is
changing branch of 5 and 6, which are now obsolete, so the cache hash changes.

In general, when cache is simply out-of-date, it can be updated using the old
version as a base. But if cache hash differs, then the cache for that
particular repo filter is recomputed (at least with the current
implementation). This is what happens here.

test-obsmarker-template.t: the pull reports 2 heads changed, but after that the
repo correctly sees only 1. The new message could be better, but it's still an
improvement over the previous one where hg pull suggested merging with an
obsolete revision.

test-obsolete.t: we can see these revisions in hg log --hidden, but they
shouldn't be considered heads even with --hidden.

test-rebase-obsolete{,2}.t: there were new heads created previously after
making new orphan changesets, but they weren't detected. Now we are properly
detecting and reporting them.

test-rebase-obsolete4.t: there's only one head now because the other head is
pruned and was falsely reported before.

test-static-http.t: add obsstore to the list of requested files. This file
doesn't exist on the remotes, but clients want it anyway (they get 404). This
is fine, because there are other nonexistent files that clients request, like
.hg/bookmarks or .hg/cache/tags2-served.

Differential Revision: https://phab.mercurial-scm.org/D12097

# bundlecaches.py - utility to deal with pre-computed bundle for servers
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from .i18n import _

from .thirdparty import attr

from . import (
    error,
    requirements as requirementsmod,
    sslutil,
    util,
)
from .utils import stringutil

urlreq = util.urlreq

CB_MANIFEST_FILE = b'clonebundles.manifest'


@attr.s
class bundlespec(object):
    compression = attr.ib()
    wirecompression = attr.ib()
    version = attr.ib()
    wireversion = attr.ib()
    params = attr.ib()
    contentopts = attr.ib()


# Maps bundle version human names to changegroup versions.
_bundlespeccgversions = {
    b'v1': b'01',
    b'v2': b'02',
    b'packed1': b's1',
    b'bundle2': b'02',  # legacy
}

# Maps bundle version with content opts to choose which part to bundle
_bundlespeccontentopts = {
    b'v1': {
        b'changegroup': True,
        b'cg.version': b'01',
        b'obsolescence': False,
        b'phases': False,
        b'tagsfnodescache': False,
        b'revbranchcache': False,
    },
    b'v2': {
        b'changegroup': True,
        b'cg.version': b'02',
        b'obsolescence': False,
        b'phases': False,
        b'tagsfnodescache': True,
        b'revbranchcache': True,
    },
    b'packed1': {b'cg.version': b's1'},
}
_bundlespeccontentopts[b'bundle2'] = _bundlespeccontentopts[b'v2']

_bundlespecvariants = {
    b"streamv2": {
        b"changegroup": False,
        b"streamv2": True,
        b"tagsfnodescache": False,
        b"revbranchcache": False,
    }
}

# Compression engines allowed in version 1. THIS SHOULD NEVER CHANGE.
_bundlespecv1compengines = {b'gzip', b'bzip2', b'none'}


def parsebundlespec(repo, spec, strict=True):
    """Parse a bundle string specification into parts.

    Bundle specifications denote a well-defined bundle/exchange format.
    The content of a given specification should not change over time in
    order to ensure that bundles produced by a newer version of Mercurial are
    readable from an older version.

    The string currently has the form:

       <compression>-<type>[;<parameter0>[;<parameter1>]]

    Where <compression> is one of the supported compression formats
    and <type> is (currently) a version string. A ";" can follow the type and
    all text afterwards is interpreted as URI encoded, ";" delimited key=value
    pairs.

    If ``strict`` is True (the default) <compression> is required. Otherwise,
    it is optional.

    Returns a bundlespec object of (compression, version, parameters).
    Compression will be ``None`` if not in strict mode and a compression isn't
    defined.

    An ``InvalidBundleSpecification`` is raised when the specification is
    not syntactically well formed.

    An ``UnsupportedBundleSpecification`` is raised when the compression or
    bundle type/version is not recognized.

    Note: this function will likely eventually return a more complex data
    structure, including bundle2 part information.
    """

    def parseparams(s):
        if b';' not in s:
            return s, {}

        params = {}
        version, paramstr = s.split(b';', 1)

        for p in paramstr.split(b';'):
            if b'=' not in p:
                raise error.InvalidBundleSpecification(
                    _(
                        b'invalid bundle specification: '
                        b'missing "=" in parameter: %s'
                    )
                    % p
                )

            key, value = p.split(b'=', 1)
            key = urlreq.unquote(key)
            value = urlreq.unquote(value)
            params[key] = value

        return version, params

    if strict and b'-' not in spec:
        raise error.InvalidBundleSpecification(
            _(
                b'invalid bundle specification; '
                b'must be prefixed with compression: %s'
            )
            % spec
        )

    if b'-' in spec:
        compression, version = spec.split(b'-', 1)

        if compression not in util.compengines.supportedbundlenames:
            raise error.UnsupportedBundleSpecification(
                _(b'%s compression is not supported') % compression
            )

        version, params = parseparams(version)

        if version not in _bundlespeccgversions:
            raise error.UnsupportedBundleSpecification(
                _(b'%s is not a recognized bundle version') % version
            )
    else:
        # Value could be just the compression or just the version, in which
        # case some defaults are assumed (but only when not in strict mode).
        assert not strict

        spec, params = parseparams(spec)

        if spec in util.compengines.supportedbundlenames:
            compression = spec
            version = b'v1'
            # Generaldelta repos require v2.
            if requirementsmod.GENERALDELTA_REQUIREMENT in repo.requirements:
                version = b'v2'
            elif requirementsmod.REVLOGV2_REQUIREMENT in repo.requirements:
                version = b'v2'
            # Modern compression engines require v2.
            if compression not in _bundlespecv1compengines:
                version = b'v2'
        elif spec in _bundlespeccgversions:
            if spec == b'packed1':
                compression = b'none'
            else:
                compression = b'bzip2'
            version = spec
        else:
            raise error.UnsupportedBundleSpecification(
                _(b'%s is not a recognized bundle specification') % spec
            )

    # Bundle version 1 only supports a known set of compression engines.
    if version == b'v1' and compression not in _bundlespecv1compengines:
        raise error.UnsupportedBundleSpecification(
            _(b'compression engine %s is not supported on v1 bundles')
            % compression
        )

    # The specification for packed1 can optionally declare the data formats
    # required to apply it. If we see this metadata, compare against what the
    # repo supports and error if the bundle isn't compatible.
    if version == b'packed1' and b'requirements' in params:
        requirements = set(params[b'requirements'].split(b','))
        missingreqs = requirements - requirementsmod.STREAM_FIXED_REQUIREMENTS
        if missingreqs:
            raise error.UnsupportedBundleSpecification(
                _(b'missing support for repository features: %s')
                % b', '.join(sorted(missingreqs))
            )

    # Compute contentopts based on the version
    contentopts = _bundlespeccontentopts.get(version, {}).copy()

    # Process the variants
    if b"stream" in params and params[b"stream"] == b"v2":
        variant = _bundlespecvariants[b"streamv2"]
        contentopts.update(variant)

    engine = util.compengines.forbundlename(compression)
    compression, wirecompression = engine.bundletype()
    wireversion = _bundlespeccgversions[version]

    return bundlespec(
        compression, wirecompression, version, wireversion, params, contentopts
    )


def parseclonebundlesmanifest(repo, s):
    """Parses the raw text of a clone bundles manifest.

    Returns a list of dicts. The dicts have a ``URL`` key corresponding
    to the URL and other keys are the attributes for the entry.
    """
    m = []
    for line in s.splitlines():
        fields = line.split()
        if not fields:
            continue
        attrs = {b'URL': fields[0]}
        for rawattr in fields[1:]:
            key, value = rawattr.split(b'=', 1)
            key = util.urlreq.unquote(key)
            value = util.urlreq.unquote(value)
            attrs[key] = value

            # Parse BUNDLESPEC into components. This makes client-side
            # preferences easier to specify since you can prefer a single
            # component of the BUNDLESPEC.
            if key == b'BUNDLESPEC':
                try:
                    bundlespec = parsebundlespec(repo, value)
                    attrs[b'COMPRESSION'] = bundlespec.compression
                    attrs[b'VERSION'] = bundlespec.version
                except error.InvalidBundleSpecification:
                    pass
                except error.UnsupportedBundleSpecification:
                    pass

        m.append(attrs)

    return m


def isstreamclonespec(bundlespec):
    # Stream clone v1
    if bundlespec.wirecompression == b'UN' and bundlespec.wireversion == b's1':
        return True

    # Stream clone v2
    if (
        bundlespec.wirecompression == b'UN'
        and bundlespec.wireversion == b'02'
        and bundlespec.contentopts.get(b'streamv2')
    ):
        return True

    return False


def filterclonebundleentries(repo, entries, streamclonerequested=False):
    """Remove incompatible clone bundle manifest entries.

    Accepts a list of entries parsed with ``parseclonebundlesmanifest``
    and returns a new list consisting of only the entries that this client
    should be able to apply.

    There is no guarantee we'll be able to apply all returned entries because
    the metadata we use to filter on may be missing or wrong.
    """
    newentries = []
    for entry in entries:
        spec = entry.get(b'BUNDLESPEC')
        if spec:
            try:
                bundlespec = parsebundlespec(repo, spec, strict=True)

                # If a stream clone was requested, filter out non-streamclone
                # entries.
                if streamclonerequested and not isstreamclonespec(bundlespec):
                    repo.ui.debug(
                        b'filtering %s because not a stream clone\n'
                        % entry[b'URL']
                    )
                    continue

            except error.InvalidBundleSpecification as e:
                repo.ui.debug(stringutil.forcebytestr(e) + b'\n')
                continue
            except error.UnsupportedBundleSpecification as e:
                repo.ui.debug(
                    b'filtering %s because unsupported bundle '
                    b'spec: %s\n' % (entry[b'URL'], stringutil.forcebytestr(e))
                )
                continue
        # If we don't have a spec and requested a stream clone, we don't know
        # what the entry is so don't attempt to apply it.
        elif streamclonerequested:
            repo.ui.debug(
                b'filtering %s because cannot determine if a stream '
                b'clone bundle\n' % entry[b'URL']
            )
            continue

        if b'REQUIRESNI' in entry and not sslutil.hassni:
            repo.ui.debug(
                b'filtering %s because SNI not supported\n' % entry[b'URL']
            )
            continue

        if b'REQUIREDRAM' in entry:
            try:
                requiredram = util.sizetoint(entry[b'REQUIREDRAM'])
            except error.ParseError:
                repo.ui.debug(
                    b'filtering %s due to a bad REQUIREDRAM attribute\n'
                    % entry[b'URL']
                )
                continue
            actualram = repo.ui.estimatememory()
            if actualram is not None and actualram * 0.66 < requiredram:
                repo.ui.debug(
                    b'filtering %s as it needs more than 2/3 of system memory\n'
                    % entry[b'URL']
                )
                continue

        newentries.append(entry)

    return newentries


class clonebundleentry(object):
    """Represents an item in a clone bundles manifest.

    This rich class is needed to support sorting since sorted() in Python 3
    doesn't support ``cmp`` and our comparison is complex enough that ``key=``
    won't work.
    """

    def __init__(self, value, prefers):
        self.value = value
        self.prefers = prefers

    def _cmp(self, other):
        for prefkey, prefvalue in self.prefers:
            avalue = self.value.get(prefkey)
            bvalue = other.value.get(prefkey)

            # Special case for b missing attribute and a matches exactly.
            if avalue is not None and bvalue is None and avalue == prefvalue:
                return -1

            # Special case for a missing attribute and b matches exactly.
            if bvalue is not None and avalue is None and bvalue == prefvalue:
                return 1

            # We can't compare unless attribute present on both.
            if avalue is None or bvalue is None:
                continue

            # Same values should fall back to next attribute.
            if avalue == bvalue:
                continue

            # Exact matches come first.
            if avalue == prefvalue:
                return -1
            if bvalue == prefvalue:
                return 1

            # Fall back to next attribute.
            continue

        # If we got here we couldn't sort by attributes and prefers. Fall
        # back to index order.
        return 0

    def __lt__(self, other):
        return self._cmp(other) < 0

    def __gt__(self, other):
        return self._cmp(other) > 0

    def __eq__(self, other):
        return self._cmp(other) == 0

    def __le__(self, other):
        return self._cmp(other) <= 0

    def __ge__(self, other):
        return self._cmp(other) >= 0

    def __ne__(self, other):
        return self._cmp(other) != 0


def sortclonebundleentries(ui, entries):
    prefers = ui.configlist(b'ui', b'clonebundleprefers')
    if not prefers:
        return list(entries)

    def _split(p):
        if b'=' not in p:
            hint = _(b"each comma separated item should be key=value pairs")
            raise error.Abort(
                _(b"invalid ui.clonebundleprefers item: %s") % p, hint=hint
            )
        return p.split(b'=', 1)

    prefers = [_split(p) for p in prefers]

    items = sorted(clonebundleentry(v, prefers) for v in entries)
    return [i.value for i in items]