view mercurial/filelog.py @ 39869:14e500b58263

revlog: add method for obtaining storage info (API)

We currently have a handful of methods on the file and manifest
storage interfaces for obtaining metadata about storage. e.g.
files() is used to obtain the files backing storage. rawsize()
is to quickly compute the size of tracked revisions without resolving
their fulltext.

Code in upgrade and stream clone make heavy use of these methods.

The existing APIs are generic and don't necessarily have the
specialization that we need going forward. For example, files()
doesn't distinguish between exclusive storage and shared storage.
This makes stream clone difficult to implement when e.g. there may
be a single file backing storage for multiple tracked paths. It
also makes reporting difficult, as we don't know how many bytes are
actually used by storage since we can't easily identify shared files.

This commit implements a new method for obtaining storage metadata.

It is designed to accept arguments specifying what metadata to request
and to return a dict with those fields populated. We /could/ make
each of these attributes a separate method. But this is a specialized
API and I'm trying to avoid method bloat on the interfaces. There is
also the possibility that certain callers will want to obtain multiple
fields in different combinations and some backends may have performance
issues obtaining all that data via separate method calls.

Simple storage integration tests have been added. For now, we assume
fields can't be "None" (ignoring the interface documentation). We can
revisit this later.

Differential Revision: https://phab.mercurial-scm.org/D4747

# filelog.py - file history class for mercurial
#
# Copyright 2005-2007 Matt Mackall <[e-mail]>
#
# 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,
    repository,
    revlog,
)
from .utils import (
    interfaceutil,
)

@interfaceutil.implementer(repository.ifilestorage)
class filelog(object):
    def __init__(self, opener, path):
        self._revlog = revlog.revlog(opener,
                                     '/'.join(('data', path + '.i')),
                                     censorable=True)
        # Full name of the user visible file, relative to the repository root.
        # Used by LFS.
        self._revlog.filename = path

    def __len__(self):
        return len(self._revlog)

    def __iter__(self):
        return self._revlog.__iter__()

    def revs(self, start=0, stop=None):
        return self._revlog.revs(start=start, stop=stop)

    def parents(self, node):
        return self._revlog.parents(node)

    def parentrevs(self, rev):
        return self._revlog.parentrevs(rev)

    def rev(self, node):
        return self._revlog.rev(node)

    def node(self, rev):
        return self._revlog.node(rev)

    def lookup(self, node):
        return self._revlog.lookup(node)

    def linkrev(self, rev):
        return self._revlog.linkrev(rev)

    # Used by verify.
    def flags(self, rev):
        return self._revlog.flags(rev)

    def commonancestorsheads(self, node1, node2):
        return self._revlog.commonancestorsheads(node1, node2)

    # Used by dagop.blockdescendants().
    def descendants(self, revs):
        return self._revlog.descendants(revs)

    def heads(self, start=None, stop=None):
        return self._revlog.heads(start, stop)

    # Used by hgweb, children extension.
    def children(self, node):
        return self._revlog.children(node)

    def deltaparent(self, rev):
        return self._revlog.deltaparent(rev)

    def iscensored(self, rev):
        return self._revlog.iscensored(rev)

    # Used by repo upgrade, verify.
    def rawsize(self, rev):
        return self._revlog.rawsize(rev)

    # Might be unused.
    def checkhash(self, text, node, p1=None, p2=None, rev=None):
        return self._revlog.checkhash(text, node, p1=p1, p2=p2, rev=rev)

    def revision(self, node, _df=None, raw=False):
        return self._revlog.revision(node, _df=_df, raw=raw)

    def revdiff(self, rev1, rev2):
        return self._revlog.revdiff(rev1, rev2)

    def emitrevisions(self, nodes, nodesorder=None,
                      revisiondata=False, assumehaveparentrevisions=False,
                      deltaprevious=False):
        return self._revlog.emitrevisions(
            nodes, nodesorder=nodesorder, revisiondata=revisiondata,
            assumehaveparentrevisions=assumehaveparentrevisions,
            deltaprevious=deltaprevious)

    def addrevision(self, revisiondata, transaction, linkrev, p1, p2,
                    node=None, flags=revlog.REVIDX_DEFAULT_FLAGS,
                    cachedelta=None):
        return self._revlog.addrevision(revisiondata, transaction, linkrev,
                                    p1, p2, node=node, flags=flags,
                                    cachedelta=cachedelta)

    def addgroup(self, deltas, linkmapper, transaction, addrevisioncb=None):
        return self._revlog.addgroup(deltas, linkmapper, transaction,
                                 addrevisioncb=addrevisioncb)

    def getstrippoint(self, minlink):
        return self._revlog.getstrippoint(minlink)

    def strip(self, minlink, transaction):
        return self._revlog.strip(minlink, transaction)

    def censorrevision(self, tr, node, tombstone=b''):
        return self._revlog.censorrevision(node, tombstone=tombstone)

    def files(self):
        return self._revlog.files()

    def read(self, node):
        t = self.revision(node)
        if not t.startswith('\1\n'):
            return t
        s = t.index('\1\n', 2)
        return t[s + 2:]

    def add(self, text, meta, transaction, link, p1=None, p2=None):
        if meta or text.startswith('\1\n'):
            text = revlog.packmeta(meta, text)
        return self.addrevision(text, transaction, link, p1, p2)

    def renamed(self, node):
        if self.parents(node)[0] != revlog.nullid:
            return False
        t = self.revision(node)
        m = revlog.parsemeta(t)[0]
        # copy and copyrev occur in pairs. In rare cases due to bugs,
        # one can occur without the other.
        if m and "copy" in m and "copyrev" in m:
            return (m["copy"], revlog.bin(m["copyrev"]))
        return False

    def size(self, rev):
        """return the size of a given revision"""

        # for revisions with renames, we have to go the slow way
        node = self.node(rev)
        if self.renamed(node):
            return len(self.read(node))
        if self.iscensored(rev):
            return 0

        # XXX if self.read(node).startswith("\1\n"), this returns (size+4)
        return self._revlog.size(rev)

    def cmp(self, node, text):
        """compare text with a given file revision

        returns True if text is different than what is stored.
        """

        t = text
        if text.startswith('\1\n'):
            t = '\1\n\1\n' + text

        samehashes = not self._revlog.cmp(node, t)
        if samehashes:
            return False

        # censored files compare against the empty file
        if self.iscensored(self.rev(node)):
            return text != ''

        # renaming a file produces a different hash, even if the data
        # remains unchanged. Check if it's the case (slow):
        if self.renamed(node):
            t2 = self.read(node)
            return t2 != text

        return True

    def verifyintegrity(self, state):
        return self._revlog.verifyintegrity(state)

    def storageinfo(self, exclusivefiles=False, sharedfiles=False,
                    revisionscount=False, trackedsize=False,
                    storedsize=False):
        return self._revlog.storageinfo(
            exclusivefiles=exclusivefiles, sharedfiles=sharedfiles,
            revisionscount=revisionscount, trackedsize=trackedsize,
            storedsize=storedsize)

    # TODO these aren't part of the interface and aren't internal methods.
    # Callers should be fixed to not use them.

    # Used by bundlefilelog, unionfilelog.
    @property
    def indexfile(self):
        return self._revlog.indexfile

    @indexfile.setter
    def indexfile(self, value):
        self._revlog.indexfile = value

    # Used by repo upgrade.
    @property
    def opener(self):
        return self._revlog.opener

    # Used by repo upgrade.
    def clone(self, tr, destrevlog, **kwargs):
        if not isinstance(destrevlog, filelog):
            raise error.ProgrammingError('expected filelog to clone()')

        return self._revlog.clone(tr, destrevlog._revlog, **kwargs)

class narrowfilelog(filelog):
    """Filelog variation to be used with narrow stores."""

    def __init__(self, opener, path, narrowmatch):
        super(narrowfilelog, self).__init__(opener, path)
        self._narrowmatch = narrowmatch

    def renamed(self, node):
        res = super(narrowfilelog, self).renamed(node)

        # Renames that come from outside the narrowspec are problematic
        # because we may lack the base text for the rename. This can result
        # in code attempting to walk the ancestry or compute a diff
        # encountering a missing revision. We address this by silently
        # removing rename metadata if the source file is outside the
        # narrow spec.
        #
        # A better solution would be to see if the base revision is available,
        # rather than assuming it isn't.
        #
        # An even better solution would be to teach all consumers of rename
        # metadata that the base revision may not be available.
        #
        # TODO consider better ways of doing this.
        if res and not self._narrowmatch(res[0]):
            return None

        return res

    def size(self, rev):
        # Because we have a custom renamed() that may lie, we need to call
        # the base renamed() to report accurate results.
        node = self.node(rev)
        if super(narrowfilelog, self).renamed(node):
            return len(self.read(node))
        else:
            return super(narrowfilelog, self).size(rev)

    def cmp(self, node, text):
        different = super(narrowfilelog, self).cmp(node, text)

        # Because renamed() may lie, we may get false positives for
        # different content. Check for this by comparing against the original
        # renamed() implementation.
        if different:
            if super(narrowfilelog, self).renamed(node):
                t2 = self.read(node)
                return t2 != text

        return different