annotate hgext/inotify/linuxserver.py @ 13158:9e7e24052745

merge: fast-forward merge with descendant

issue2538 gives a case where a changeset is merged with its child (which is on
another branch), and to my surprise the result is a real merge with two
parents, not just a "fast forward" "merge" with only the child as parent.

That is essentially the same as issue619.

Is the existing behaviour as intended and correct?

Or is the following fix correct?

Some extra "created new head" pops up with this fix, but it seems to me like
they could be considered correct. The old branch head has been superseeded by
changes on the other branch, and when the changes on the other branch is merged
back to the branch it will introduce a new head not directly related to the
previous branch head.

(I guess the intention with existing behaviour could be to ensure that the
changesets on the branch are directly connected and that no new heads pops up
on merges.)

# linuxserver.py - inotify status server for linux
#
# Copyright 2006, 2007, 2008 Bryan O'Sullivan <[e-mail]>
# Copyright 2007, 2008 Brendan Cully <[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 import osutil, util
import server
import errno, os, select, stat, sys, time

try:
    import linux as inotify
    from linux import watcher
except ImportError:
    raise

def walkrepodirs(dirstate, absroot):
    '''Iterate over all subdirectories of this repo.
    Exclude the .hg directory, any nested repos, and ignored dirs.'''
    def walkit(dirname, top):
        fullpath = server.join(absroot, dirname)
        try:
            for name, kind in osutil.listdir(fullpath):
                if kind == stat.S_IFDIR:
                    if name == '.hg':
                        if not top:
                            return
                    else:
                        d = server.join(dirname, name)
                        if dirstate._ignore(d):
                            continue
                        for subdir in walkit(d, False):
                            yield subdir
        except OSError, err:
            if err.errno not in server.walk_ignored_errors:
                raise
        yield fullpath

    return walkit('', True)

def _explain_watch_limit(ui, dirstate, rootabs):
    path = '/proc/sys/fs/inotify/max_user_watches'
    try:
        limit = int(file(path).read())
    except IOError, err:
        if err.errno != errno.ENOENT:
            raise
        raise util.Abort(_('this system does not seem to '
                           'support inotify'))
    ui.warn(_('*** the current per-user limit on the number '
              'of inotify watches is %s\n') % limit)
    ui.warn(_('*** this limit is too low to watch every '
              'directory in this repository\n'))
    ui.warn(_('*** counting directories: '))
    ndirs = len(list(walkrepodirs(dirstate, rootabs)))
    ui.warn(_('found %d\n') % ndirs)
    newlimit = min(limit, 1024)
    while newlimit < ((limit + ndirs) * 1.1):
        newlimit *= 2
    ui.warn(_('*** to raise the limit from %d to %d (run as root):\n') %
            (limit, newlimit))
    ui.warn(_('***  echo %d > %s\n') % (newlimit, path))
    raise util.Abort(_('cannot watch %s until inotify watch limit is raised')
                     % rootabs)

class pollable(object):
    """
    Interface to support polling.
    The file descriptor returned by fileno() is registered to a polling
    object.
    Usage:
        Every tick, check if an event has happened since the last tick:
        * If yes, call handle_events
        * If no, call handle_timeout
    """
    poll_events = select.POLLIN
    instances = {}
    poll = select.poll()

    def fileno(self):
        raise NotImplementedError

    def handle_events(self, events):
        raise NotImplementedError

    def handle_timeout(self):
        raise NotImplementedError

    def shutdown(self):
        raise NotImplementedError

    def register(self, timeout):
        fd = self.fileno()

        pollable.poll.register(fd, pollable.poll_events)
        pollable.instances[fd] = self

        self.registered = True
        self.timeout = timeout

    def unregister(self):
        pollable.poll.unregister(self)
        self.registered = False

    @classmethod
    def run(cls):
        while True:
            timeout = None
            timeobj = None
            for obj in cls.instances.itervalues():
                if obj.timeout is not None and (timeout is None
                                                or obj.timeout < timeout):
                    timeout, timeobj = obj.timeout, obj
            try:
                events = cls.poll.poll(timeout)
            except select.error, err:
                if err.args[0] == errno.EINTR:
                    continue
                raise
            if events:
                by_fd = {}
                for fd, event in events:
                    by_fd.setdefault(fd, []).append(event)

                for fd, events in by_fd.iteritems():
                    cls.instances[fd].handle_pollevents(events)

            elif timeobj:
                timeobj.handle_timeout()

def eventaction(code):
    """
    Decorator to help handle events in repowatcher
    """
    def decorator(f):
        def wrapper(self, wpath):
            if code == 'm' and wpath in self.lastevent and \
                self.lastevent[wpath] in 'cm':
                return
            self.lastevent[wpath] = code
            self.timeout = 250

            f(self, wpath)

        wrapper.func_name = f.func_name
        return wrapper
    return decorator

class repowatcher(server.repowatcher, pollable):
    """
    Watches inotify events
    """
    mask = (
        inotify.IN_ATTRIB |
        inotify.IN_CREATE |
        inotify.IN_DELETE |
        inotify.IN_DELETE_SELF |
        inotify.IN_MODIFY |
        inotify.IN_MOVED_FROM |
        inotify.IN_MOVED_TO |
        inotify.IN_MOVE_SELF |
        inotify.IN_ONLYDIR |
        inotify.IN_UNMOUNT |
        0)

    def __init__(self, ui, dirstate, root):
        server.repowatcher.__init__(self, ui, dirstate, root)

        self.lastevent = {}
        self.dirty = False
        try:
            self.watcher = watcher.watcher()
        except OSError, err:
            raise util.Abort(_('inotify service not available: %s') %
                             err.strerror)
        self.threshold = watcher.threshold(self.watcher)
        self.fileno = self.watcher.fileno
        self.register(timeout=None)

        self.handle_timeout()
        self.scan()

    def event_time(self):
        last = self.last_event
        now = time.time()
        self.last_event = now

        if last is None:
            return 'start'
        delta = now - last
        if delta < 5:
            return '+%.3f' % delta
        if delta < 50:
            return '+%.2f' % delta
        return '+%.1f' % delta

    def add_watch(self, path, mask):
        if not path:
            return
        if self.watcher.path(path) is None:
            if self.ui.debugflag:
                self.ui.note(_('watching %r\n') % path[self.prefixlen:])
            try:
                self.watcher.add(path, mask)
            except OSError, err:
                if err.errno in (errno.ENOENT, errno.ENOTDIR):
                    return
                if err.errno != errno.ENOSPC:
                    raise
                _explain_watch_limit(self.ui, self.dirstate, self.wprefix)

    def setup(self):
        self.ui.note(_('watching directories under %r\n') % self.wprefix)
        self.add_watch(self.wprefix + '.hg', inotify.IN_DELETE)

    def scan(self, topdir=''):
        ds = self.dirstate._map.copy()
        self.add_watch(server.join(self.wprefix, topdir), self.mask)
        for root, dirs, files in server.walk(self.dirstate, self.wprefix,
                                             topdir):
            for d in dirs:
                self.add_watch(server.join(root, d), self.mask)
            wroot = root[self.prefixlen:]
            for fn in files:
                wfn = server.join(wroot, fn)
                self.updatefile(wfn, self.getstat(wfn))
                ds.pop(wfn, None)
        wtopdir = topdir
        if wtopdir and wtopdir[-1] != '/':
            wtopdir += '/'
        for wfn, state in ds.iteritems():
            if not wfn.startswith(wtopdir):
                continue
            try:
                st = self.stat(wfn)
            except OSError:
                status = state[0]
                self.deletefile(wfn, status)
            else:
                self.updatefile(wfn, st)
        self.check_deleted('!')
        self.check_deleted('r')

    @eventaction('c')
    def created(self, wpath):
        if wpath == '.hgignore':
            self.update_hgignore()
        try:
            st = self.stat(wpath)
            if stat.S_ISREG(st[0]) or stat.S_ISLNK(st[0]):
                self.updatefile(wpath, st)
        except OSError:
            pass

    @eventaction('m')
    def modified(self, wpath):
        if wpath == '.hgignore':
            self.update_hgignore()
        try:
            st = self.stat(wpath)
            if stat.S_ISREG(st[0]):
                if self.dirstate[wpath] in 'lmn':
                    self.updatefile(wpath, st)
        except OSError:
            pass

    @eventaction('d')
    def deleted(self, wpath):
        if wpath == '.hgignore':
            self.update_hgignore()
        elif wpath.startswith('.hg/'):
            return

        self.deletefile(wpath, self.dirstate[wpath])

    def process_create(self, wpath, evt):
        if self.ui.debugflag:
            self.ui.note(_('%s event: created %s\n') %
                         (self.event_time(), wpath))

        if evt.mask & inotify.IN_ISDIR:
            self.scan(wpath)
        else:
            self.created(wpath)

    def process_delete(self, wpath, evt):
        if self.ui.debugflag:
            self.ui.note(_('%s event: deleted %s\n') %
                         (self.event_time(), wpath))

        if evt.mask & inotify.IN_ISDIR:
            tree = self.tree.dir(wpath)
            todelete = [wfn for wfn, ignore in tree.walk('?')]
            for fn in todelete:
                self.deletefile(fn, '?')
            self.scan(wpath)
        else:
            self.deleted(wpath)

    def process_modify(self, wpath, evt):
        if self.ui.debugflag:
            self.ui.note(_('%s event: modified %s\n') %
                         (self.event_time(), wpath))

        if not (evt.mask & inotify.IN_ISDIR):
            self.modified(wpath)

    def process_unmount(self, evt):
        self.ui.warn(_('filesystem containing %s was unmounted\n') %
                     evt.fullpath)
        sys.exit(0)

    def handle_pollevents(self, events):
        if self.ui.debugflag:
            self.ui.note(_('%s readable: %d bytes\n') %
                         (self.event_time(), self.threshold.readable()))
        if not self.threshold():
            if self.registered:
                if self.ui.debugflag:
                    self.ui.note(_('%s below threshold - unhooking\n') %
                                 (self.event_time()))
                self.unregister()
                self.timeout = 250
        else:
            self.read_events()

    def read_events(self, bufsize=None):
        events = self.watcher.read(bufsize)
        if self.ui.debugflag:
            self.ui.note(_('%s reading %d events\n') %
                         (self.event_time(), len(events)))
        for evt in events:
            if evt.fullpath == self.wprefix[:-1]:
                # events on the root of the repository
                # itself, e.g. permission changes or repository move
                continue
            assert evt.fullpath.startswith(self.wprefix)
            wpath = evt.fullpath[self.prefixlen:]

            # paths have been normalized, wpath never ends with a '/'

            if wpath.startswith('.hg/') and evt.mask & inotify.IN_ISDIR:
                # ignore subdirectories of .hg/ (merge, patches...)
                continue
            if wpath == ".hg/wlock":
                if evt.mask & inotify.IN_DELETE:
                    self.dirstate.invalidate()
                    self.dirty = False
                    self.scan()
                elif evt.mask & inotify.IN_CREATE:
                    self.dirty = True
            else:
                if self.dirty:
                    continue

                if evt.mask & inotify.IN_UNMOUNT:
                    self.process_unmount(wpath, evt)
                elif evt.mask & (inotify.IN_MODIFY | inotify.IN_ATTRIB):
                    self.process_modify(wpath, evt)
                elif evt.mask & (inotify.IN_DELETE | inotify.IN_DELETE_SELF |
                                 inotify.IN_MOVED_FROM):
                    self.process_delete(wpath, evt)
                elif evt.mask & (inotify.IN_CREATE | inotify.IN_MOVED_TO):
                    self.process_create(wpath, evt)

        self.lastevent.clear()

    def handle_timeout(self):
        if not self.registered:
            if self.ui.debugflag:
                self.ui.note(_('%s hooking back up with %d bytes readable\n') %
                             (self.event_time(), self.threshold.readable()))
            self.read_events(0)
            self.register(timeout=None)

        self.timeout = None

    def shutdown(self):
        self.watcher.close()

    def debug(self):
        """
        Returns a sorted list of relatives paths currently watched,
        for debugging purposes.
        """
        return sorted(tuple[0][self.prefixlen:] for tuple in self.watcher)

class socketlistener(server.socketlistener, pollable):
    """
    Listens for client queries on unix socket inotify.sock
    """
    def __init__(self, ui, root, repowatcher, timeout):
        server.socketlistener.__init__(self, ui, root, repowatcher, timeout)
        self.register(timeout=timeout)

    def handle_timeout(self):
        raise server.TimeoutException

    def handle_pollevents(self, events):
        for e in events:
            self.accept_connection()

    def shutdown(self):
        self.sock.close()
        try:
            os.unlink(self.sockpath)
            if self.realsockpath:
                os.unlink(self.realsockpath)
                os.rmdir(os.path.dirname(self.realsockpath))
        except OSError, err:
            if err.errno != errno.ENOENT:
                raise

    def answer_stat_query(self, cs):
        if self.repowatcher.timeout:
            # We got a query while a rescan is pending.  Make sure we
            # rescan before responding, or we could give back a wrong
            # answer.
            self.repowatcher.handle_timeout()
        return server.socketlistener.answer_stat_query(self, cs)

class master(object):
    def __init__(self, ui, dirstate, root, timeout=None):
        self.ui = ui
        self.repowatcher = repowatcher(ui, dirstate, root)
        self.socketlistener = socketlistener(ui, root, self.repowatcher,
                                             timeout)

    def shutdown(self):
        for obj in pollable.instances.itervalues():
            obj.shutdown()

    def run(self):
        self.repowatcher.setup()
        self.ui.note(_('finished setup\n'))
        if os.getenv('TIME_STARTUP'):
            sys.exit(0)
        pollable.run()