hgext/largefiles/lfcommands.py

largefiles: don't verify largefile hashes on servers when processing statlfile

When changesets referencing largefiles are pushed then the corresponding
largefiles will be pushed too - unless the target already has them. The client
will use statlfile to make sure it only sends largefiles that the target
doesn't have. The server would however on every statlfile check that the
content of the largefile had the expected hash. What should be cheap thus
became an expensive operation that trashed the disk and the cache.

Largefile hashes are already checked by putlfile before being stored on the
server. A server should thus be able to keep its largefile store free of
errors - even more than it can keep revlogs free of errors. Verification should
happen when running 'hg verify' locally on the server. Rehashing every
largefile on every remote stat is too expensive.

Clients will also stat lfiles before downloading them. When the server verified
the hash in stat it meant that it had to read the file twice to serve it.

With this change the server will assume its own hashes are ok without checking
them on every statlfile.

Some consequences of this change:
- in case of server side corruption the problem will be detected by the
  existing check on the client side - not on server side
- clients that could upload an uncorrupted largefile when pushing will no
  longer magically heal the server (and break hardlinks) - a client will now
  only upload its uncorrupted files after the corrupted file has been removed
  on the server side
- client side verify will no longer report corruption in files it doesn't have

(Issue3123 discussed related problems - and how they have been fixed.)

# Copyright 2009-2010 Gregory P. Ward
# Copyright 2009-2010 Intelerad Medical Systems Incorporated
# Copyright 2010-2011 Fog Creek Software
# Copyright 2010-2011 Unity Technologies
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

'''High-level command function for lfconvert, plus the cmdtable.'''

import os
import shutil

from mercurial import util, match as match_, hg, node, context, error, \
    cmdutil, scmutil, commands
from mercurial.i18n import _
from mercurial.lock import release

import lfutil
import basestore

# -- Commands ----------------------------------------------------------

def lfconvert(ui, src, dest, *pats, **opts):
    '''convert a normal repository to a largefiles repository

    Convert repository SOURCE to a new repository DEST, identical to
    SOURCE except that certain files will be converted as largefiles:
    specifically, any file that matches any PATTERN *or* whose size is
    above the minimum size threshold is converted as a largefile. The
    size used to determine whether or not to track a file as a
    largefile is the size of the first version of the file. The
    minimum size can be specified either with --size or in
    configuration as ``largefiles.size``.

    After running this command you will need to make sure that
    largefiles is enabled anywhere you intend to push the new
    repository.

    Use --to-normal to convert largefiles back to normal files; after
    this, the DEST repository can be used without largefiles at all.'''

    if opts['to_normal']:
        tolfile = False
    else:
        tolfile = True
        size = lfutil.getminsize(ui, True, opts.get('size'), default=None)

    if not hg.islocal(src):
        raise util.Abort(_('%s is not a local Mercurial repo') % src)
    if not hg.islocal(dest):
        raise util.Abort(_('%s is not a local Mercurial repo') % dest)

    rsrc = hg.repository(ui, src)
    ui.status(_('initializing destination %s\n') % dest)
    rdst = hg.repository(ui, dest, create=True)

    success = False
    dstwlock = dstlock = None
    try:
        # Lock destination to prevent modification while it is converted to.
        # Don't need to lock src because we are just reading from its history
        # which can't change.
        dstwlock = rdst.wlock()
        dstlock = rdst.lock()

        # Get a list of all changesets in the source.  The easy way to do this
        # is to simply walk the changelog, using changelog.nodesbetween().
        # Take a look at mercurial/revlog.py:639 for more details.
        # Use a generator instead of a list to decrease memory usage
        ctxs = (rsrc[ctx] for ctx in rsrc.changelog.nodesbetween(None,
            rsrc.heads())[0])
        revmap = {node.nullid: node.nullid}
        if tolfile:
            lfiles = set()
            normalfiles = set()
            if not pats:
                pats = ui.configlist(lfutil.longname, 'patterns', default=[])
            if pats:
                matcher = match_.match(rsrc.root, '', list(pats))
            else:
                matcher = None

            lfiletohash = {}
            for ctx in ctxs:
                ui.progress(_('converting revisions'), ctx.rev(),
                    unit=_('revision'), total=rsrc['tip'].rev())
                _lfconvert_addchangeset(rsrc, rdst, ctx, revmap,
                    lfiles, normalfiles, matcher, size, lfiletohash)
            ui.progress(_('converting revisions'), None)

            if os.path.exists(rdst.wjoin(lfutil.shortname)):
                shutil.rmtree(rdst.wjoin(lfutil.shortname))

            for f in lfiletohash.keys():
                if os.path.isfile(rdst.wjoin(f)):
                    os.unlink(rdst.wjoin(f))
                try:
                    os.removedirs(os.path.dirname(rdst.wjoin(f)))
                except OSError:
                    pass

            # If there were any files converted to largefiles, add largefiles
            # to the destination repository's requirements.
            if lfiles:
                rdst.requirements.add('largefiles')
                rdst._writerequirements()
        else:
            for ctx in ctxs:
                ui.progress(_('converting revisions'), ctx.rev(),
                    unit=_('revision'), total=rsrc['tip'].rev())
                _addchangeset(ui, rsrc, rdst, ctx, revmap)

            ui.progress(_('converting revisions'), None)
        success = True
    finally:
        rdst.dirstate.clear()
        release(dstlock, dstwlock)
        if not success:
            # we failed, remove the new directory
            shutil.rmtree(rdst.root)

def _addchangeset(ui, rsrc, rdst, ctx, revmap):
    # Convert src parents to dst parents
    parents = _convertparents(ctx, revmap)

    # Generate list of changed files
    files = _getchangedfiles(ctx, parents)

    def getfilectx(repo, memctx, f):
        if lfutil.standin(f) in files:
            # if the file isn't in the manifest then it was removed
            # or renamed, raise IOError to indicate this
            try:
                fctx = ctx.filectx(lfutil.standin(f))
            except error.LookupError:
                raise IOError
            renamed = fctx.renamed()
            if renamed:
                renamed = lfutil.splitstandin(renamed[0])

            hash = fctx.data().strip()
            path = lfutil.findfile(rsrc, hash)

            # If one file is missing, likely all files from this rev are
            if path is None:
                cachelfiles(ui, rsrc, ctx.node())
                path = lfutil.findfile(rsrc, hash)

                if path is None:
                    raise util.Abort(
                        _("missing largefile \'%s\' from revision %s")
                         % (f, node.hex(ctx.node())))

            data = ''
            fd = None
            try:
                fd = open(path, 'rb')
                data = fd.read()
            finally:
                if fd:
                    fd.close()
            return context.memfilectx(f, data, 'l' in fctx.flags(),
                                      'x' in fctx.flags(), renamed)
        else:
            return _getnormalcontext(repo.ui, ctx, f, revmap)

    dstfiles = []
    for file in files:
        if lfutil.isstandin(file):
            dstfiles.append(lfutil.splitstandin(file))
        else:
            dstfiles.append(file)
    # Commit
    _commitcontext(rdst, parents, ctx, dstfiles, getfilectx, revmap)

def _lfconvert_addchangeset(rsrc, rdst, ctx, revmap, lfiles, normalfiles,
        matcher, size, lfiletohash):
    # Convert src parents to dst parents
    parents = _convertparents(ctx, revmap)

    # Generate list of changed files
    files = _getchangedfiles(ctx, parents)

    dstfiles = []
    for f in files:
        if f not in lfiles and f not in normalfiles:
            islfile = _islfile(f, ctx, matcher, size)
            # If this file was renamed or copied then copy
            # the largefile-ness of its predecessor
            if f in ctx.manifest():
                fctx = ctx.filectx(f)
                renamed = fctx.renamed()
                renamedlfile = renamed and renamed[0] in lfiles
                islfile |= renamedlfile
                if 'l' in fctx.flags():
                    if renamedlfile:
                        raise util.Abort(
                            _('renamed/copied largefile %s becomes symlink')
                            % f)
                    islfile = False
            if islfile:
                lfiles.add(f)
            else:
                normalfiles.add(f)

        if f in lfiles:
            dstfiles.append(lfutil.standin(f))
            # largefile in manifest if it has not been removed/renamed
            if f in ctx.manifest():
                fctx = ctx.filectx(f)
                if 'l' in fctx.flags():
                    renamed = fctx.renamed()
                    if renamed and renamed[0] in lfiles:
                        raise util.Abort(_('largefile %s becomes symlink') % f)

                # largefile was modified, update standins
                fullpath = rdst.wjoin(f)
                util.makedirs(os.path.dirname(fullpath))
                m = util.sha1('')
                m.update(ctx[f].data())
                hash = m.hexdigest()
                if f not in lfiletohash or lfiletohash[f] != hash:
                    try:
                        fd = open(fullpath, 'wb')
                        fd.write(ctx[f].data())
                    finally:
                        if fd:
                            fd.close()
                    executable = 'x' in ctx[f].flags()
                    os.chmod(fullpath, lfutil.getmode(executable))
                    lfutil.writestandin(rdst, lfutil.standin(f), hash,
                        executable)
                    lfiletohash[f] = hash
        else:
            # normal file
            dstfiles.append(f)

    def getfilectx(repo, memctx, f):
        if lfutil.isstandin(f):
            # if the file isn't in the manifest then it was removed
            # or renamed, raise IOError to indicate this
            srcfname = lfutil.splitstandin(f)
            try:
                fctx = ctx.filectx(srcfname)
            except error.LookupError:
                raise IOError
            renamed = fctx.renamed()
            if renamed:
                # standin is always a largefile because largefile-ness
                # doesn't change after rename or copy
                renamed = lfutil.standin(renamed[0])

            return context.memfilectx(f, lfiletohash[srcfname] + '\n', 'l' in
                fctx.flags(), 'x' in fctx.flags(), renamed)
        else:
            return _getnormalcontext(repo.ui, ctx, f, revmap)

    # Commit
    _commitcontext(rdst, parents, ctx, dstfiles, getfilectx, revmap)

def _commitcontext(rdst, parents, ctx, dstfiles, getfilectx, revmap):
    mctx = context.memctx(rdst, parents, ctx.description(), dstfiles,
                          getfilectx, ctx.user(), ctx.date(), ctx.extra())
    ret = rdst.commitctx(mctx)
    rdst.setparents(ret)
    revmap[ctx.node()] = rdst.changelog.tip()

# Generate list of changed files
def _getchangedfiles(ctx, parents):
    files = set(ctx.files())
    if node.nullid not in parents:
        mc = ctx.manifest()
        mp1 = ctx.parents()[0].manifest()
        mp2 = ctx.parents()[1].manifest()
        files |= (set(mp1) | set(mp2)) - set(mc)
        for f in mc:
            if mc[f] != mp1.get(f, None) or mc[f] != mp2.get(f, None):
                files.add(f)
    return files

# Convert src parents to dst parents
def _convertparents(ctx, revmap):
    parents = []
    for p in ctx.parents():
        parents.append(revmap[p.node()])
    while len(parents) < 2:
        parents.append(node.nullid)
    return parents

# Get memfilectx for a normal file
def _getnormalcontext(ui, ctx, f, revmap):
    try:
        fctx = ctx.filectx(f)
    except error.LookupError:
        raise IOError
    renamed = fctx.renamed()
    if renamed:
        renamed = renamed[0]

    data = fctx.data()
    if f == '.hgtags':
        data = _converttags (ui, revmap, data)
    return context.memfilectx(f, data, 'l' in fctx.flags(),
                              'x' in fctx.flags(), renamed)

# Remap tag data using a revision map
def _converttags(ui, revmap, data):
    newdata = []
    for line in data.splitlines():
        try:
            id, name = line.split(' ', 1)
        except ValueError:
            ui.warn(_('skipping incorrectly formatted tag %s\n'
                % line))
            continue
        try:
            newid = node.bin(id)
        except TypeError:
            ui.warn(_('skipping incorrectly formatted id %s\n'
                % id))
            continue
        try:
            newdata.append('%s %s\n' % (node.hex(revmap[newid]),
                name))
        except KeyError:
            ui.warn(_('no mapping for id %s\n') % id)
            continue
    return ''.join(newdata)

def _islfile(file, ctx, matcher, size):
    '''Return true if file should be considered a largefile, i.e.
    matcher matches it or it is larger than size.'''
    # never store special .hg* files as largefiles
    if file == '.hgtags' or file == '.hgignore' or file == '.hgsigs':
        return False
    if matcher and matcher(file):
        return True
    try:
        return ctx.filectx(file).size() >= size * 1024 * 1024
    except error.LookupError:
        return False

def uploadlfiles(ui, rsrc, rdst, files):
    '''upload largefiles to the central store'''

    if not files:
        return

    store = basestore._openstore(rsrc, rdst, put=True)

    at = 0
    ui.debug("sending statlfile command for %d largefiles\n" % len(files))
    retval = store.exists(files)
    files = filter(lambda h: not retval[h], files)
    ui.debug("%d largefiles need to be uploaded\n" % len(files))

    for hash in files:
        ui.progress(_('uploading largefiles'), at, unit='largefile',
                    total=len(files))
        source = lfutil.findfile(rsrc, hash)
        if not source:
            raise util.Abort(_('largefile %s missing from store'
                               ' (needs to be uploaded)') % hash)
        # XXX check for errors here
        store.put(source, hash)
        at += 1
    ui.progress(_('uploading largefiles'), None)

def verifylfiles(ui, repo, all=False, contents=False):
    '''Verify that every big file revision in the current changeset
    exists in the central store.  With --contents, also verify that
    the contents of each big file revision are correct (SHA-1 hash
    matches the revision ID).  With --all, check every changeset in
    this repository.'''
    if all:
        # Pass a list to the function rather than an iterator because we know a
        # list will work.
        revs = range(len(repo))
    else:
        revs = ['.']

    store = basestore._openstore(repo)
    return store.verify(revs, contents=contents)

def debugdirstate(ui, repo):
    '''Show basic information for the largefiles dirstate'''
    lfdirstate = lfutil.openlfdirstate(ui, repo)
    for file_, ent in sorted(lfdirstate._map.iteritems()):
        mode = '%3o' % (ent[1] & 0777 & ~util.umask)
        ui.write("%c %s %10d %s\n" % (ent[0], mode, ent[2], file_))

def cachelfiles(ui, repo, node, filelist=None):
    '''cachelfiles ensures that all largefiles needed by the specified revision
    are present in the repository's largefile cache.

    returns a tuple (cached, missing).  cached is the list of files downloaded
    by this operation; missing is the list of files that were needed but could
    not be found.'''
    lfiles = lfutil.listlfiles(repo, node)
    if filelist:
        lfiles = set(lfiles) & set(filelist)
    toget = []

    for lfile in lfiles:
        # If we are mid-merge, then we have to trust the standin that is in the
        # working copy to have the correct hashvalue.  This is because the
        # original hg.merge() already updated the standin as part of the normal
        # merge process -- we just have to update the largefile to match.
        if (getattr(repo, "_ismerging", False) and
             os.path.exists(repo.wjoin(lfutil.standin(lfile)))):
            expectedhash = lfutil.readstandin(repo, lfile)
        else:
            expectedhash = repo[node][lfutil.standin(lfile)].data().strip()

        # if it exists and its hash matches, it might have been locally
        # modified before updating and the user chose 'local'.  in this case,
        # it will not be in any store, so don't look for it.
        if ((not os.path.exists(repo.wjoin(lfile)) or
             expectedhash != lfutil.hashfile(repo.wjoin(lfile))) and
            not lfutil.findfile(repo, expectedhash)):
            toget.append((lfile, expectedhash))

    if toget:
        store = basestore._openstore(repo)
        ret = store.get(toget)
        return ret

    return ([], [])

def downloadlfiles(ui, repo, rev=None):
    matchfn = scmutil.match(repo[None],
                            [repo.wjoin(lfutil.shortname)], {})
    def prepare(ctx, fns):
        pass
    totalsuccess = 0
    totalmissing = 0
    for ctx in cmdutil.walkchangerevs(repo, matchfn, {'rev' : rev},
                                      prepare):
        success, missing = cachelfiles(ui, repo, ctx.node())
        totalsuccess += len(success)
        totalmissing += len(missing)
    ui.status(_("%d additional largefiles cached\n") % totalsuccess)
    if totalmissing > 0:
        ui.status(_("%d largefiles failed to download\n") % totalmissing)
    return totalsuccess, totalmissing

def updatelfiles(ui, repo, filelist=None, printmessage=True):
    wlock = repo.wlock()
    try:
        lfdirstate = lfutil.openlfdirstate(ui, repo)
        lfiles = set(lfutil.listlfiles(repo)) | set(lfdirstate)

        if filelist is not None:
            lfiles = [f for f in lfiles if f in filelist]

        printed = False
        if printmessage and lfiles:
            ui.status(_('getting changed largefiles\n'))
            printed = True
            cachelfiles(ui, repo, '.', lfiles)

        updated, removed = 0, 0
        for f in lfiles:
            i = _updatelfile(repo, lfdirstate, f)
            if i:
                if i > 0:
                    updated += i
                else:
                    removed -= i
            if printmessage and (removed or updated) and not printed:
                ui.status(_('getting changed largefiles\n'))
                printed = True

        lfdirstate.write()
        if printed and printmessage:
            ui.status(_('%d largefiles updated, %d removed\n') % (updated,
                removed))
    finally:
        wlock.release()

def _updatelfile(repo, lfdirstate, lfile):
    '''updates a single largefile and copies the state of its standin from
    the repository's dirstate to its state in the lfdirstate.

    returns 1 if the file was modified, -1 if the file was removed, 0 if the
    file was unchanged, and None if the needed largefile was missing from the
    cache.'''
    ret = 0
    abslfile = repo.wjoin(lfile)
    absstandin = repo.wjoin(lfutil.standin(lfile))
    if os.path.exists(absstandin):
        if os.path.exists(absstandin + '.orig') and os.path.exists(abslfile):
            shutil.copyfile(abslfile, abslfile + '.orig')
        expecthash = lfutil.readstandin(repo, lfile)
        if (expecthash != '' and
            (not os.path.exists(abslfile) or
             expecthash != lfutil.hashfile(abslfile))):
            if not lfutil.copyfromcache(repo, expecthash, lfile):
                # use normallookup() to allocate entry in largefiles dirstate,
                # because lack of it misleads lfilesrepo.status() into
                # recognition that such cache missing files are REMOVED.
                lfdirstate.normallookup(lfile)
                return None # don't try to set the mode
            else:
                # Synchronize largefile dirstate to the last modified time of
                # the file
                lfdirstate.normal(lfile)
            ret = 1
        mode = os.stat(absstandin).st_mode
        if mode != os.stat(abslfile).st_mode:
            os.chmod(abslfile, mode)
            ret = 1
    else:
        # Remove lfiles for which the standin is deleted, unless the
        # lfile is added to the repository again. This happens when a
        # largefile is converted back to a normal file: the standin
        # disappears, but a new (normal) file appears as the lfile.
        if os.path.exists(abslfile) and lfile not in repo[None]:
            util.unlinkpath(abslfile)
            ret = -1
    state = repo.dirstate[lfutil.standin(lfile)]
    if state == 'n':
        # When rebasing, we need to synchronize the standin and the largefile,
        # because otherwise the largefile will get reverted.  But for commit's
        # sake, we have to mark the file as unclean.
        if getattr(repo, "_isrebasing", False):
            lfdirstate.normallookup(lfile)
        else:
            lfdirstate.normal(lfile)
    elif state == 'r':
        lfdirstate.remove(lfile)
    elif state == 'a':
        lfdirstate.add(lfile)
    elif state == '?':
        lfdirstate.drop(lfile)
    return ret

def catlfile(repo, lfile, rev, filename):
    hash = lfutil.readstandin(repo, lfile, rev)
    if not lfutil.inusercache(repo.ui, hash):
        store = basestore._openstore(repo)
        success, missing = store.get([(lfile, hash)])
        if len(success) != 1:
            raise util.Abort(
                _('largefile %s is not in cache and could not be downloaded')
                    % lfile)
    path = lfutil.usercachepath(repo.ui, hash)
    fpout = cmdutil.makefileobj(repo, filename)
    fpin = open(path, "rb")
    fpout.write(fpin.read())
    fpout.close()
    fpin.close()
    return 0

# -- hg commands declarations ------------------------------------------------

cmdtable = {
    'lfconvert': (lfconvert,
                  [('s', 'size', '',
                    _('minimum size (MB) for files to be converted '
                      'as largefiles'),
                    'SIZE'),
                  ('', 'to-normal', False,
                   _('convert from a largefiles repo to a normal repo')),
                  ],
                  _('hg lfconvert SOURCE DEST [FILE ...]')),
    }

commands.inferrepo += " lfconvert"