mercurial/bookmarks.py

changelog: rework the delayupdate mechanism

The current way we use the 'delayupdate' mechanism is wrong. We call
'delayupdate' right after the transaction retrieval, then we call 'finalize'
right before calling 'tr.close()'. The 'finalize' call will -always- result in a
flush to disk, making the data available to all readers. But the 'tr.close()' may
be a no-op if the transaction is nested. This would result in data:

1) exposed to reader too early,
2) rolled back by other part of the transaction after such exposure

So we need to end up in a situation where we call 'finalize' a single time when
the transaction actually closes. For this purpose we need to be able to call
'delayupdate' and '_writepending' multiple times and 'finalize' once. This was
not possible with the previous state of the code.

This changeset refactors the code to makes this possible. We buffer data in memory
as much as possible and fall-back to writing to a ".a" file after the first call
to '_writepending'.

# Mercurial bookmark support code
#
# Copyright 2008 David Soria Parra <[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 mercurial.i18n import _
from mercurial.node import hex, bin
from mercurial import encoding, error, util, obsolete, lock as lockmod
import errno

class bmstore(dict):
    """Storage for bookmarks.

    This object should do all bookmark reads and writes, so that it's
    fairly simple to replace the storage underlying bookmarks without
    having to clone the logic surrounding bookmarks.

    This particular bmstore implementation stores bookmarks as
    {hash}\s{name}\n (the same format as localtags) in
    .hg/bookmarks. The mapping is stored as {name: nodeid}.

    This class does NOT handle the "current" bookmark state at this
    time.
    """

    def __init__(self, repo):
        dict.__init__(self)
        self._repo = repo
        try:
            for line in repo.vfs('bookmarks'):
                line = line.strip()
                if not line:
                    continue
                if ' ' not in line:
                    repo.ui.warn(_('malformed line in .hg/bookmarks: %r\n')
                                 % line)
                    continue
                sha, refspec = line.split(' ', 1)
                refspec = encoding.tolocal(refspec)
                try:
                    self[refspec] = repo.changelog.lookup(sha)
                except LookupError:
                    pass
        except IOError, inst:
            if inst.errno != errno.ENOENT:
                raise

    def recordchange(self, tr):
        """record that bookmarks have been changed in a transaction

        The transaction is then responsible for updating the file content."""
        tr.addfilegenerator('bookmarks', ('bookmarks',), self._write,
                            vfs=self._repo.vfs)
        tr.hookargs['bookmark_moved'] = '1'

    def write(self):
        '''Write bookmarks

        Write the given bookmark => hash dictionary to the .hg/bookmarks file
        in a format equal to those of localtags.

        We also store a backup of the previous state in undo.bookmarks that
        can be copied back on rollback.
        '''
        repo = self._repo
        if repo._bookmarkcurrent not in self:
            unsetcurrent(repo)

        wlock = repo.wlock()
        try:

            file = repo.vfs('bookmarks', 'w', atomictemp=True)
            self._write(file)
            file.close()

            # touch 00changelog.i so hgweb reloads bookmarks (no lock needed)
            try:
                repo.svfs.utime('00changelog.i', None)
            except OSError:
                pass

        finally:
            wlock.release()

    def _write(self, fp):
        for name, node in self.iteritems():
            fp.write("%s %s\n" % (hex(node), encoding.fromlocal(name)))

def readcurrent(repo):
    '''Get the current bookmark

    If we use gittish branches we have a current bookmark that
    we are on. This function returns the name of the bookmark. It
    is stored in .hg/bookmarks.current
    '''
    mark = None
    try:
        file = repo.opener('bookmarks.current')
    except IOError, inst:
        if inst.errno != errno.ENOENT:
            raise
        return None
    try:
        # No readline() in osutil.posixfile, reading everything is cheap
        mark = encoding.tolocal((file.readlines() or [''])[0])
        if mark == '' or mark not in repo._bookmarks:
            mark = None
    finally:
        file.close()
    return mark

def setcurrent(repo, mark):
    '''Set the name of the bookmark that we are currently on

    Set the name of the bookmark that we are on (hg update <bookmark>).
    The name is recorded in .hg/bookmarks.current
    '''
    if mark not in repo._bookmarks:
        raise AssertionError('bookmark %s does not exist!' % mark)

    current = repo._bookmarkcurrent
    if current == mark:
        return

    wlock = repo.wlock()
    try:
        file = repo.opener('bookmarks.current', 'w', atomictemp=True)
        file.write(encoding.fromlocal(mark))
        file.close()
    finally:
        wlock.release()
    repo._bookmarkcurrent = mark

def unsetcurrent(repo):
    wlock = repo.wlock()
    try:
        try:
            repo.vfs.unlink('bookmarks.current')
            repo._bookmarkcurrent = None
        except OSError, inst:
            if inst.errno != errno.ENOENT:
                raise
    finally:
        wlock.release()

def iscurrent(repo, mark=None, parents=None):
    '''Tell whether the current bookmark is also active

    I.e., the bookmark listed in .hg/bookmarks.current also points to a
    parent of the working directory.
    '''
    if not mark:
        mark = repo._bookmarkcurrent
    if not parents:
        parents = [p.node() for p in repo[None].parents()]
    marks = repo._bookmarks
    return (mark in marks and marks[mark] in parents)

def updatecurrentbookmark(repo, oldnode, curbranch):
    try:
        return update(repo, oldnode, repo.branchtip(curbranch))
    except error.RepoLookupError:
        if curbranch == "default": # no default branch!
            return update(repo, oldnode, repo.lookup("tip"))
        else:
            raise util.Abort(_("branch %s not found") % curbranch)

def deletedivergent(repo, deletefrom, bm):
    '''Delete divergent versions of bm on nodes in deletefrom.

    Return True if at least one bookmark was deleted, False otherwise.'''
    deleted = False
    marks = repo._bookmarks
    divergent = [b for b in marks if b.split('@', 1)[0] == bm.split('@', 1)[0]]
    for mark in divergent:
        if mark == '@' or '@' not in mark:
            # can't be divergent by definition
            continue
        if mark and marks[mark] in deletefrom:
            if mark != bm:
                del marks[mark]
                deleted = True
    return deleted

def calculateupdate(ui, repo, checkout):
    '''Return a tuple (targetrev, movemarkfrom) indicating the rev to
    check out and where to move the active bookmark from, if needed.'''
    movemarkfrom = None
    if checkout is None:
        curmark = repo._bookmarkcurrent
        if iscurrent(repo):
            movemarkfrom = repo['.'].node()
        elif curmark:
            ui.status(_("updating to active bookmark %s\n") % curmark)
            checkout = curmark
    return (checkout, movemarkfrom)

def update(repo, parents, node):
    deletefrom = parents
    marks = repo._bookmarks
    update = False
    cur = repo._bookmarkcurrent
    if not cur:
        return False

    if marks[cur] in parents:
        new = repo[node]
        divs = [repo[b] for b in marks
                if b.split('@', 1)[0] == cur.split('@', 1)[0]]
        anc = repo.changelog.ancestors([new.rev()])
        deletefrom = [b.node() for b in divs if b.rev() in anc or b == new]
        if validdest(repo, repo[marks[cur]], new):
            marks[cur] = new.node()
            update = True

    if deletedivergent(repo, deletefrom, cur):
        update = True

    if update:
        marks.write()
    return update

def listbookmarks(repo):
    # We may try to list bookmarks on a repo type that does not
    # support it (e.g., statichttprepository).
    marks = getattr(repo, '_bookmarks', {})

    d = {}
    hasnode = repo.changelog.hasnode
    for k, v in marks.iteritems():
        # don't expose local divergent bookmarks
        if hasnode(v) and ('@' not in k or k.endswith('@')):
            d[k] = hex(v)
    return d

def pushbookmark(repo, key, old, new):
    w = l = tr = None
    try:
        w = repo.wlock()
        l = repo.lock()
        tr = repo.transaction('bookmarks')
        marks = repo._bookmarks
        existing = hex(marks.get(key, ''))
        if existing != old and existing != new:
            return False
        if new == '':
            del marks[key]
        else:
            if new not in repo:
                return False
            marks[key] = repo[new].node()
        marks.recordchange(tr)
        tr.close()
        return True
    finally:
        lockmod.release(tr, l, w)

def compare(repo, srcmarks, dstmarks,
            srchex=None, dsthex=None, targets=None):
    '''Compare bookmarks between srcmarks and dstmarks

    This returns tuple "(addsrc, adddst, advsrc, advdst, diverge,
    differ, invalid)", each are list of bookmarks below:

    :addsrc:  added on src side (removed on dst side, perhaps)
    :adddst:  added on dst side (removed on src side, perhaps)
    :advsrc:  advanced on src side
    :advdst:  advanced on dst side
    :diverge: diverge
    :differ:  changed, but changeset referred on src is unknown on dst
    :invalid: unknown on both side
    :same:    same on both side

    Each elements of lists in result tuple is tuple "(bookmark name,
    changeset ID on source side, changeset ID on destination
    side)". Each changeset IDs are 40 hexadecimal digit string or
    None.

    Changeset IDs of tuples in "addsrc", "adddst", "differ" or
     "invalid" list may be unknown for repo.

    This function expects that "srcmarks" and "dstmarks" return
    changeset ID in 40 hexadecimal digit string for specified
    bookmark. If not so (e.g. bmstore "repo._bookmarks" returning
    binary value), "srchex" or "dsthex" should be specified to convert
    into such form.

    If "targets" is specified, only bookmarks listed in it are
    examined.
    '''
    if not srchex:
        srchex = lambda x: x
    if not dsthex:
        dsthex = lambda x: x

    if targets:
        bset = set(targets)
    else:
        srcmarkset = set(srcmarks)
        dstmarkset = set(dstmarks)
        bset = srcmarkset | dstmarkset

    results = ([], [], [], [], [], [], [], [])
    addsrc = results[0].append
    adddst = results[1].append
    advsrc = results[2].append
    advdst = results[3].append
    diverge = results[4].append
    differ = results[5].append
    invalid = results[6].append
    same = results[7].append

    for b in sorted(bset):
        if b not in srcmarks:
            if b in dstmarks:
                adddst((b, None, dsthex(dstmarks[b])))
            else:
                invalid((b, None, None))
        elif b not in dstmarks:
            addsrc((b, srchex(srcmarks[b]), None))
        else:
            scid = srchex(srcmarks[b])
            dcid = dsthex(dstmarks[b])
            if scid == dcid:
                same((b, scid, dcid))
            elif scid in repo and dcid in repo:
                sctx = repo[scid]
                dctx = repo[dcid]
                if sctx.rev() < dctx.rev():
                    if validdest(repo, sctx, dctx):
                        advdst((b, scid, dcid))
                    else:
                        diverge((b, scid, dcid))
                else:
                    if validdest(repo, dctx, sctx):
                        advsrc((b, scid, dcid))
                    else:
                        diverge((b, scid, dcid))
            else:
                # it is too expensive to examine in detail, in this case
                differ((b, scid, dcid))

    return results

def _diverge(ui, b, path, localmarks):
    if b == '@':
        b = ''
    # find a unique @ suffix
    for x in range(1, 100):
        n = '%s@%d' % (b, x)
        if n not in localmarks:
            break
    # try to use an @pathalias suffix
    # if an @pathalias already exists, we overwrite (update) it
    if path.startswith("file:"):
        path = util.url(path).path
    for p, u in ui.configitems("paths"):
        if u.startswith("file:"):
            u = util.url(u).path
        if path == u:
            n = '%s@%s' % (b, p)
    return n

def updatefromremote(ui, repo, remotemarks, path, trfunc, explicit=()):
    ui.debug("checking for updated bookmarks\n")
    localmarks = repo._bookmarks
    (addsrc, adddst, advsrc, advdst, diverge, differ, invalid, same
     ) = compare(repo, remotemarks, localmarks, dsthex=hex)

    status = ui.status
    warn = ui.warn
    if ui.configbool('ui', 'quietbookmarkmove', False):
        status = warn = ui.debug

    explicit = set(explicit)
    changed = []
    for b, scid, dcid in addsrc:
        if scid in repo: # add remote bookmarks for changes we already have
            changed.append((b, bin(scid), status,
                            _("adding remote bookmark %s\n") % (b)))
    for b, scid, dcid in advsrc:
        changed.append((b, bin(scid), status,
                        _("updating bookmark %s\n") % (b)))
    # remove normal movement from explicit set
    explicit.difference_update(d[0] for d in changed)

    for b, scid, dcid in diverge:
        if b in explicit:
            explicit.discard(b)
            changed.append((b, bin(scid), status,
                            _("importing bookmark %s\n") % (b)))
        else:
            db = _diverge(ui, b, path, localmarks)
            changed.append((db, bin(scid), warn,
                            _("divergent bookmark %s stored as %s\n")
                            % (b, db)))
    for b, scid, dcid in adddst + advdst:
        if b in explicit:
            explicit.discard(b)
            changed.append((b, bin(scid), status,
                            _("importing bookmark %s\n") % (b)))

    if changed:
        tr = trfunc()
        for b, node, writer, msg in sorted(changed):
            localmarks[b] = node
            writer(msg)
        localmarks.recordchange(tr)

def diff(ui, dst, src):
    ui.status(_("searching for changed bookmarks\n"))

    smarks = src.listkeys('bookmarks')
    dmarks = dst.listkeys('bookmarks')

    diff = sorted(set(smarks) - set(dmarks))
    for k in diff:
        mark = ui.debugflag and smarks[k] or smarks[k][:12]
        ui.write("   %-25s %s\n" % (k, mark))

    if len(diff) <= 0:
        ui.status(_("no changed bookmarks found\n"))
        return 1
    return 0

def validdest(repo, old, new):
    """Is the new bookmark destination a valid update from the old one"""
    repo = repo.unfiltered()
    if old == new:
        # Old == new -> nothing to update.
        return False
    elif not old:
        # old is nullrev, anything is valid.
        # (new != nullrev has been excluded by the previous check)
        return True
    elif repo.obsstore:
        return new.node() in obsolete.foreground(repo, [old.node()])
    else:
        # still an independent clause as it is lazyer (and therefore faster)
        return old.descendant(new)