hgext/inotify/server.py

inotify: close most file descriptors when autostarting
Otherwise, operations that autostart while talking to an SSH repository
prevent SSH stderr from closing normally. This causes hangs at
the end of hg clone or hg pull -u.

# server.py - inotify status server
#
# 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, incorporated herein by reference.

from mercurial.i18n import _
from mercurial import osutil, util
import common
import errno, os, select, socket, stat, struct, sys, tempfile, time

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

class AlreadyStartedException(Exception): pass

def join(a, b):
    if a:
        if a[-1] == '/':
            return a + b
        return a + '/' + b
    return b

walk_ignored_errors = (errno.ENOENT, errno.ENAMETOOLONG)

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

def walk(repo, root):
    '''Like os.walk, but only yields regular files.'''

    # This function is critical to performance during startup.

    reporoot = root == ''
    rootslash = repo.root + os.sep

    def walkit(root, reporoot):
        files, dirs = [], []
        hginside = False

        try:
            fullpath = rootslash + root
            for name, kind in osutil.listdir(fullpath):
                if kind == stat.S_IFDIR:
                    if name == '.hg':
                        hginside = True
                        if reporoot:
                            continue
                        else:
                            break
                    dirs.append(name)
                elif kind in (stat.S_IFREG, stat.S_IFLNK):
                    path = join(root, name)
                    files.append((name, kind))

            yield hginside, fullpath, dirs, files

            for subdir in dirs:
                path = join(root, subdir)
                if repo.dirstate._ignore(path):
                    continue
                for result in walkit(path, False):
                    if not result[0]:
                        yield result
        except OSError, err:
            if err.errno not in walk_ignored_errors:
                raise
    for result in walkit(root, reporoot):
        yield result[1:]

def _explain_watch_limit(ui, repo, count):
    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(repo)))
    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')
                     % repo.root)

class Watcher(object):
    poll_events = select.POLLIN
    statuskeys = 'almr!?'

    def __init__(self, ui, repo, master):
        self.ui = ui
        self.repo = repo
        self.wprefix = self.repo.wjoin('')
        self.timeout = None
        self.master = master
        self.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)
        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.registered = True
        self.fileno = self.watcher.fileno

        self.repo.dirstate.__class__.inotifyserver = True

        self.tree = {}
        self.statcache = {}
        self.statustrees = dict([(s, {}) for s in self.statuskeys])

        self.watches = 0
        self.last_event = None

        self.eventq = {}
        self.deferred = 0

        self.ds_info = self.dirstate_info()
        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 dirstate_info(self):
        try:
            st = os.lstat(self.repo.join('dirstate'))
            return st.st_mtime, st.st_ino
        except OSError, err:
            if err.errno != errno.ENOENT:
                raise
            return 0, 0

    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[len(self.wprefix):])
            try:
                self.watcher.add(path, mask)
                self.watches += 1
            except OSError, err:
                if err.errno in (errno.ENOENT, errno.ENOTDIR):
                    return
                if err.errno != errno.ENOSPC:
                    raise
                _explain_watch_limit(self.ui, self.repo, self.watches)

    def setup(self):
        self.ui.note(_('watching directories under %r\n') % self.repo.root)
        self.add_watch(self.repo.path, inotify.IN_DELETE)
        self.check_dirstate()

    def wpath(self, evt):
        path = evt.fullpath
        if path == self.repo.root:
            return ''
        if path.startswith(self.wprefix):
            return path[len(self.wprefix):]
        raise 'wtf? ' + path

    def dir(self, tree, path):
        if path:
            for name in path.split('/'):
                tree.setdefault(name, {})
                tree = tree[name]
        return tree

    def lookup(self, path, tree):
        if path:
            try:
                for name in path.split('/'):
                    tree = tree[name]
            except KeyError:
                return 'x'
            except TypeError:
                return 'd'
        return tree

    def split(self, path):
        c = path.rfind('/')
        if c == -1:
            return '', path
        return path[:c], path[c+1:]

    def filestatus(self, fn, st):
        try:
            type_, mode, size, time = self.repo.dirstate._map[fn][:4]
        except KeyError:
            type_ = '?'
        if type_ == 'n':
            if not st:
                return '!'
            st_mode, st_size, st_mtime = st
            if size == -1:
                return 'l'
            if size and (size != st_size or (mode ^ st_mode) & 0100):
                return 'm'
            if time != int(st_mtime):
                return 'l'
            return 'n'
        if type_ in 'ma' and not st:
            return '!'
        if type_ == '?' and self.repo.dirstate._ignore(fn):
            return 'i'
        return type_

    def updatestatus(self, wfn, st=None, status=None):
        if st:
            status = self.filestatus(wfn, st)
        else:
            self.statcache.pop(wfn, None)
        root, fn = self.split(wfn)
        d = self.dir(self.tree, root)
        oldstatus = d.get(fn)
        isdir = False
        if oldstatus:
            try:
                if not status:
                    if oldstatus in 'almn':
                        status = '!'
                    elif oldstatus == 'r':
                        status = 'r'
            except TypeError:
                # oldstatus may be a dict left behind by a deleted
                # directory
                isdir = True
            else:
                if oldstatus in self.statuskeys and oldstatus != status:
                    del self.dir(self.statustrees[oldstatus], root)[fn]
        if self.ui.debugflag and oldstatus != status:
            if isdir:
                self.ui.note(_('status: %r dir(%d) -> %s\n') %
                             (wfn, len(oldstatus), status))
            else:
                self.ui.note(_('status: %r %s -> %s\n') %
                             (wfn, oldstatus, status))
        if not isdir:
            if status and status != 'i':
                d[fn] = status
                if status in self.statuskeys:
                    dd = self.dir(self.statustrees[status], root)
                    if oldstatus != status or fn not in dd:
                        dd[fn] = status
            else:
                d.pop(fn, None)

    def check_deleted(self, key):
        # Files that had been deleted but were present in the dirstate
        # may have vanished from the dirstate; we must clean them up.
        nuke = []
        for wfn, ignore in self.walk(key, self.statustrees[key]):
            if wfn not in self.repo.dirstate:
                nuke.append(wfn)
        for wfn in nuke:
            root, fn = self.split(wfn)
            del self.dir(self.statustrees[key], root)[fn]
            del self.dir(self.tree, root)[fn]

    def scan(self, topdir=''):
        self.handle_timeout()
        ds = self.repo.dirstate._map.copy()
        self.add_watch(join(self.repo.root, topdir), self.mask)
        for root, dirs, entries in walk(self.repo, topdir):
            for d in dirs:
                self.add_watch(join(root, d), self.mask)
            wroot = root[len(self.wprefix):]
            d = self.dir(self.tree, wroot)
            for fn, kind in entries:
                wfn = join(wroot, fn)
                self.updatestatus(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.updatestatus(wfn, None, status=status)
            else:
                self.updatestatus(wfn, st)
        self.check_deleted('!')
        self.check_deleted('r')

    def check_dirstate(self):
        ds_info = self.dirstate_info()
        if ds_info == self.ds_info:
            return
        self.ds_info = ds_info
        if not self.ui.debugflag:
            self.last_event = None
        self.ui.note(_('%s dirstate reload\n') % self.event_time())
        self.repo.dirstate.invalidate()
        self.scan()
        self.ui.note(_('%s end dirstate reload\n') % self.event_time())

    def walk(self, states, tree, prefix=''):
        # This is the "inner loop" when talking to the client.

        for name, val in tree.iteritems():
            path = join(prefix, name)
            try:
                if val in states:
                    yield path, val
            except TypeError:
                for p in self.walk(states, val, path):
                    yield p

    def update_hgignore(self):
        # An update of the ignore file can potentially change the
        # states of all unknown and ignored files.

        # XXX If the user has other ignore files outside the repo, or
        # changes their list of ignore files at run time, we'll
        # potentially never see changes to them.  We could get the
        # client to report to us what ignore data they're using.
        # But it's easier to do nothing than to open that can of
        # worms.

        if '_ignore' in self.repo.dirstate.__dict__:
            delattr(self.repo.dirstate, '_ignore')
            self.ui.note(_('rescanning due to .hgignore change\n'))
            self.scan()

    def getstat(self, wpath):
        try:
            return self.statcache[wpath]
        except KeyError:
            try:
                return self.stat(wpath)
            except OSError, err:
                if err.errno != errno.ENOENT:
                    raise

    def stat(self, wpath):
        try:
            st = os.lstat(join(self.wprefix, wpath))
            ret = st.st_mode, st.st_size, st.st_mtime
            self.statcache[wpath] = ret
            return ret
        except OSError:
            self.statcache.pop(wpath, None)
            raise

    def created(self, wpath):
        if wpath == '.hgignore':
            self.update_hgignore()
        try:
            st = self.stat(wpath)
            if stat.S_ISREG(st[0]):
                self.updatestatus(wpath, st)
        except OSError:
            pass

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

    def deleted(self, wpath):
        if wpath == '.hgignore':
            self.update_hgignore()
        elif wpath.startswith('.hg/'):
            if wpath == '.hg/wlock':
                self.check_dirstate()
            return

        self.updatestatus(wpath, None)

    def schedule_work(self, wpath, evt):
        self.eventq.setdefault(wpath, [])
        prev = self.eventq[wpath]
        try:
            if prev and evt == 'm' and prev[-1] in 'cm':
                return
            self.eventq[wpath].append(evt)
        finally:
            self.deferred += 1
            self.timeout = 250

    def deferred_event(self, wpath, evt):
        if evt == 'c':
            self.created(wpath)
        elif evt == 'm':
            self.modified(wpath)
        elif evt == 'd':
            self.deleted(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.schedule_work(wpath, 'c')

    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:
            self.scan(wpath)
        else:
            self.schedule_work(wpath, 'd')

    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.schedule_work(wpath, 'm')

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

    def handle_event(self, fd, event):
        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.master.poll.unregister(fd)
                self.registered = False
                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:
            wpath = self.wpath(evt)
            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)

    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.master.poll.register(self, select.POLLIN)
            self.registered = True

        if self.eventq:
            if self.ui.debugflag:
                self.ui.note(_('%s processing %d deferred events as %d\n') %
                             (self.event_time(), self.deferred,
                              len(self.eventq)))
            for wpath, evts in util.sort(self.eventq.items()):
                for evt in evts:
                    self.deferred_event(wpath, evt)
            self.eventq.clear()
            self.deferred = 0
        self.timeout = None

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

class Server(object):
    poll_events = select.POLLIN

    def __init__(self, ui, repo, watcher, timeout):
        self.ui = ui
        self.repo = repo
        self.watcher = watcher
        self.timeout = timeout
        self.sock = socket.socket(socket.AF_UNIX)
        self.sockpath = self.repo.join('inotify.sock')
        self.realsockpath = None
        try:
            self.sock.bind(self.sockpath)
        except socket.error, err:
            if err[0] == errno.EADDRINUSE:
                raise AlreadyStartedException(_('could not start server: %s')
                                              % err[1])
            if err[0] == "AF_UNIX path too long":
                tempdir = tempfile.mkdtemp(prefix="hg-inotify-")
                self.realsockpath = os.path.join(tempdir, "inotify.sock")
                try:
                    self.sock.bind(self.realsockpath)
                    os.symlink(self.realsockpath, self.sockpath)
                except (OSError, socket.error), inst:
                    try:
                        os.unlink(self.realsockpath)
                    except:
                        pass
                    os.rmdir(tempdir)
                    if inst.errno == errno.EEXIST:
                        raise AlreadyStartedException(_('could not start server: %s')
                                                      % inst.strerror)
                    raise
            else:
                raise
        self.sock.listen(5)
        self.fileno = self.sock.fileno

    def handle_timeout(self):
        pass

    def handle_event(self, fd, event):
        sock, addr = self.sock.accept()

        cs = common.recvcs(sock)
        version = ord(cs.read(1))

        sock.sendall(chr(common.version))

        if version != common.version:
            self.ui.warn(_('received query from incompatible client '
                           'version %d\n') % version)
            return

        names = cs.read().split('\0')

        states = names.pop()

        self.ui.note(_('answering query for %r\n') % states)

        if self.watcher.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.watcher.handle_timeout()

        if not names:
            def genresult(states, tree):
                for fn, state in self.watcher.walk(states, tree):
                    yield fn
        else:
            def genresult(states, tree):
                for fn in names:
                    l = self.watcher.lookup(fn, tree)
                    try:
                        if l in states:
                            yield fn
                    except TypeError:
                        for f, s in self.watcher.walk(states, l, fn):
                            yield f

        results = ['\0'.join(r) for r in [
            genresult('l', self.watcher.statustrees['l']),
            genresult('m', self.watcher.statustrees['m']),
            genresult('a', self.watcher.statustrees['a']),
            genresult('r', self.watcher.statustrees['r']),
            genresult('!', self.watcher.statustrees['!']),
            '?' in states and genresult('?', self.watcher.statustrees['?']) or [],
            [],
            'c' in states and genresult('n', self.watcher.tree) or [],
            ]]

        try:
            try:
                sock.sendall(struct.pack(common.resphdrfmt,
                                         *map(len, results)))
                sock.sendall(''.join(results))
            finally:
                sock.shutdown(socket.SHUT_WR)
        except socket.error, err:
            if err[0] != errno.EPIPE:
                raise

    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

class Master(object):
    def __init__(self, ui, repo, timeout=None):
        self.ui = ui
        self.repo = repo
        self.poll = select.poll()
        self.watcher = Watcher(ui, repo, self)
        self.server = Server(ui, repo, self.watcher, timeout)
        self.table = {}
        for obj in (self.watcher, self.server):
            fd = obj.fileno()
            self.table[fd] = obj
            self.poll.register(fd, obj.poll_events)

    def register(self, fd, mask):
        self.poll.register(fd, mask)

    def shutdown(self):
        for obj in self.table.itervalues():
            obj.shutdown()

    def run(self):
        self.watcher.setup()
        self.ui.note(_('finished setup\n'))
        if os.getenv('TIME_STARTUP'):
            sys.exit(0)
        while True:
            timeout = None
            timeobj = None
            for obj in self.table.itervalues():
                if obj.timeout is not None and (timeout is None or obj.timeout < timeout):
                    timeout, timeobj = obj.timeout, obj
            try:
                if self.ui.debugflag:
                    if timeout is None:
                        self.ui.note(_('polling: no timeout\n'))
                    else:
                        self.ui.note(_('polling: %sms timeout\n') % timeout)
                events = self.poll.poll(timeout)
            except select.error, err:
                if err[0] == errno.EINTR:
                    continue
                raise
            if events:
                for fd, event in events:
                    self.table[fd].handle_event(fd, event)
            elif timeobj:
                timeobj.handle_timeout()

def start(ui, repo):
    def closefds(ignore):
        # (from python bug #1177468)
        # close all inherited file descriptors
        # Python 2.4.1 and later use /dev/urandom to seed the random module's RNG
        # a file descriptor is kept internally as os._urandomfd (created on demand
        # the first time os.urandom() is called), and should not be closed
        try:
            os.urandom(4)
            urandom_fd = getattr(os, '_urandomfd', None)
        except AttributeError:
            urandom_fd = None
        ignore.append(urandom_fd)
        for fd in range(3, 256):
            if fd in ignore:
                continue
            try:
                os.close(fd)
            except OSError:
                pass

    m = Master(ui, repo)
    sys.stdout.flush()
    sys.stderr.flush()

    pid = os.fork()
    if pid:
        return pid

    closefds([m.server.fileno(), m.watcher.fileno()])
    os.setsid()

    fd = os.open('/dev/null', os.O_RDONLY)
    os.dup2(fd, 0)
    if fd > 0:
        os.close(fd)

    fd = os.open(ui.config('inotify', 'log', '/dev/null'),
                 os.O_RDWR | os.O_CREAT | os.O_TRUNC)
    os.dup2(fd, 1)
    os.dup2(fd, 2)
    if fd > 2:
        os.close(fd)

    try:
        m.run()
    finally:
        m.shutdown()
        os._exit(0)