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Python Open Source » Database » Python Remote Objects 
Python Remote Objects » Pyro 3.10 » Pyro » naming.py
#############################################################################
#
#  $Id: naming.py,v 2.64.2.25 2009/07/12 15:38:25 irmen Exp $
#  Pyro Name Server
#
#  This is part of "Pyro" - Python Remote Objects
#  which is (c) Irmen de Jong - irmen@users.sourceforge.net
#
#############################################################################

import sys, os, socket, time, traceback, errno
import dircache, shutil, SocketServer
import Pyro.constants, Pyro.core, Pyro.errors, Pyro.protocol, Pyro.util
if Pyro.util.supports_multithreading():
  import threading

NS_SYSCMD_LOCATION='location'
NS_SYSCMD_SHUTDOWN='shutdown'

Log = Pyro.util.Log

#############################################################################
#
# The Pyro NameServer Locator.
# Use a broadcast mechanism to find the broadcast server of the NS which
# can provide us with the URI of the NS.
# Can also perform direct lookup (no broadcast) if the host is specified.
# (in that case, the 'port' argument is the Pyro port, not a broadcast port).
#
#############################################################################

class NameServerLocator(object):
  def __init__(self, identification=None):
    Pyro.core._checkInit()  # init required
    self.identification=identification

  def sendSysCommand(self,request,host=None,port=None,trace=0,logerrors=1,bcaddr=None):
    try:
      # Try the 'first' name server.
      # Note that if no host is specified, a broadcast is used,
      # and that one is sent to both name servers in parallel.
      return self.__sendSysCommand(request, host, port, trace, logerrors, Pyro.constants.NSROLE_PRIMARY, bcaddr)
    except KeyboardInterrupt:
      raise
    except (socket.error, Pyro.errors.PyroError):
      if not port:
        # the 'first' name server failed, try the second
        try:
          result=self.__sendSysCommand(request, host, port, trace, logerrors, Pyro.constants.NSROLE_SECONDARY, bcaddr)
          # found the second!
          # switch config for first and second so that the second one (which we found) will now be tried first
          Pyro.config.PYRO_NS2_HOSTNAME, Pyro.config.PYRO_NS_HOSTNAME = Pyro.config.PYRO_NS_HOSTNAME, Pyro.config.PYRO_NS2_HOSTNAME
          Pyro.config.PYRO_NS2_PORT, Pyro.config.PYRO_NS_PORT = Pyro.config.PYRO_NS_PORT, Pyro.config.PYRO_NS2_PORT
          Pyro.config.PYRO_NS2_BC_PORT, Pyro.config.PYRO_NS_BC_PORT = Pyro.config.PYRO_NS_BC_PORT, Pyro.config.PYRO_NS2_BC_PORT
          Pyro.config.PYRO_NS2_BC_ADDR, Pyro.config.PYRO_NS_BC_ADDR = Pyro.config.PYRO_NS_BC_ADDR, Pyro.config.PYRO_NS2_BC_ADDR
          return result
        except (socket.error, Pyro.errors.PyroError):
          # Could not find using broadcast. Try the current host and localhost as well.
          # But only if there's no explicit host parameter given.
          if host:
            raise Pyro.errors.NamingError("could not find NameServer on host "+host)
          else:
            for host in (Pyro.protocol.getHostname(), "localhost"):
              if trace:
                print "Trying host",host
              Log.msg('NameServerLocator','Trying host',host)
              try:
                result=self.__sendSysCommand(request, host, port, trace, logerrors, Pyro.constants.NSROLE_PRIMARY)
                Pyro.config.PYRO_NS_HOSTNAME = host
                return result
              except Pyro.errors.ConnectionDeniedError:
                  raise
              except (socket.error, Pyro.errors.PyroError),x:
                pass
            else:
              raise Pyro.errors.NamingError("could not find NameServer")
      else:
        raise

  def __sendSysCommand(self,request,host=None,port=None,trace=0,logerrors=1,role=Pyro.constants.NSROLE_PRIMARY,bcaddr=None):
    HPB={Pyro.constants.NSROLE_PRIMARY: (Pyro.config.PYRO_NS_HOSTNAME, Pyro.config.PYRO_NS_PORT, Pyro.config.PYRO_NS_BC_PORT, Pyro.config.PYRO_NS_BC_ADDR),
         Pyro.constants.NSROLE_SECONDARY: (Pyro.config.PYRO_NS2_HOSTNAME, Pyro.config.PYRO_NS2_PORT, Pyro.config.PYRO_NS2_BC_PORT, Pyro.config.PYRO_NS2_BC_ADDR) }
    if not host:
      host=HPB[role][0]
    if port:
      port1=port2=port
    else:
      if not host:
        # select the default broadcast ports
        port1 = HPB[Pyro.constants.NSROLE_PRIMARY][2]
        port2 = HPB[Pyro.constants.NSROLE_SECONDARY][2]
      else:
        # select the default port (normal)
        port = HPB[role][1]
    # We must discover the location of the name server.
    # Pyro's NS can answer to broadcast requests.
    try:
      if host:
        # use direct lookup with PYROLOC: mechanism, no broadcast
        if trace:
          print 'Locator: contacting Pyro Name Server...'
        uri=Pyro.core.PyroURI(host,Pyro.constants.NAMESERVER_NAME,port,'PYROLOC')
        prox=Pyro.core.getProxyForURI(uri)
        prox._setIdentification(self.identification)
        if request==NS_SYSCMD_LOCATION:
          prox.ping()  # force resolving of PYROLOC: uri
          return prox.URI # return resolved uri
        elif request==NS_SYSCMD_SHUTDOWN:
          return prox._shutdown()
        else:
          raise ValueError("invalid command specified")

      # No host specified. Use broadcast mechanism
      if os.name=='java' and sys.version_info<(2,5):
        # jythons older than 2.5 don't have working broadcast
        msg="Skipping UDP broadcast (older jythons don't support this operation)"
        if trace:
          print msg
        raise Pyro.errors.PyroError(msg)
      if bcaddr:
        try:
          socket.gethostbyname(bcaddr)
        except socket.error:
          msg="invalid broadcast address '%s'" % bcaddr
          if trace:
            print msg
          raise ValueError(msg)
        destination1 = (bcaddr, port1)
        destination2 = (bcaddr, port2)
      else:
        destination1 = (Pyro.config.PYRO_NS_BC_ADDR or '<broadcast>', port1)
        destination2 = (Pyro.config.PYRO_NS2_BC_ADDR or '<broadcast>', port2)
      s = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
      if hasattr(socket,'SO_BROADCAST'):
        s.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
      
      if trace:
        print 'Locator: searching Pyro Name Server...'
      try:
        bc_retries=Pyro.config.PYRO_BC_RETRIES
        if bc_retries<0:
          bc_retries=sys.maxint-1
        bc_retries = min(sys.maxint-1, bc_retries)
        for i in xrange(bc_retries+1):
          # send request to both Pyro NS (if running in paired mode)
          s.sendto(request, destination1)
          if destination2!=destination1:
            s.sendto(request, destination2)
          timeout=min(sys.maxint,Pyro.config.PYRO_BC_TIMEOUT)
          if timeout<0:
            timeout=None
          ins,outs,exs = Pyro.protocol.safe_select([s],[],[s],timeout)
          if s in ins:
            # return the info of the first NS that responded.
            reply, fromaddr = s.recvfrom(1000)
            return reply
          if trace and i<Pyro.config.PYRO_BC_RETRIES:
            print 'Locator: retry',i+1
      finally:
        s.close()
    except socket.error,e:
      if logerrors:
        Log.error('NameServerLocator','network error:',e)
      if trace:
        print 'Locator: network error:',e
      raise
    if logerrors:
      Log.error('NameServerLocator','Name Server not responding to broadcast')
    raise Pyro.errors.PyroError('Name Server not responding')
  
  def detectNS(self,host=None,port=None,trace=0,bcaddr=None):
    # just try to detect an existing NS. Don't log errors
    return Pyro.core.PyroURI(self.sendSysCommand(NS_SYSCMD_LOCATION,host,port,trace,0,bcaddr))

  def getNS(self,host=None,port=None,trace=0,bcaddr=None):
    reply = self.sendSysCommand(NS_SYSCMD_LOCATION,host,port,trace,1,bcaddr)
    Log.msg('NameServerLocator','Name Server found:',reply)
    ns=NameServerProxy(Pyro.core.PyroURI(reply),self.identification)
    ns._setIdentification(self.identification)
    return ns
    

# NOTE: The NameServerProxy class below is hand crafted.
# This is because we want to enforce the default group name on all name
# arguments that are not absolute.
# In doing so, we make sure that each object name is passed as an
# absolute name (from the name space root) too. This is needed because
# the NS has no state and can only process absolute names for each request.
# Also, the PYRO_NS_DEFAULTGROUP configitem is used to expand non-absolute
# names to absolute names. Because this is done in the proxy, each
# client can have its own PYRO_NS_DEFAULTGROUP.

class NameServerProxy(object):
  def __init__(self,URI,identification=None,noconnect=0):
    self.URI = URI
    self.objectID = URI.objectID
    self.adapter = Pyro.protocol.getProtocolAdapter(self.URI.protocol)
    self.adapter.setIdentification(identification)
    if noconnect:
      self.adapter.URI=URI.clone()
    else:
      self.adapter.bindToURI(URI)
    self.adapter.setOneway(["_synccall"])
  def _release(self):
    if self.adapter:
      self.adapter.release()
      
  def __remoteinvoc(self, *args):
    try:
      if not self.adapter.connected():
        # rebind here, don't do it from inside the remoteInvocation because deadlock will occur
        self.adapter.bindToURI(self.URI)
      return self.adapter.remoteInvocation(*args)
    except Pyro.errors.ProtocolError,x:
      # The remote invocation failed. Try to find the NS again.
      Log.warn('NameServerProxy','Name Server communication problem:',x,' URI was:',self.URI)
      Log.msg('NameServerProxy','trying to find NS again...')
      self.URI=NameServerLocator().detectNS()
      self.objectID=self.URI.objectID
      self.adapter.bindToURI(self.URI)
      Log.msg('NameServerProxy','found NS at',self.URI,".... retry call")
      return self.adapter.remoteInvocation(*args)
      
  def ping(self):
    return self.__remoteinvoc('ping',0)
  def resync(self):
    return self.__remoteinvoc('resync',0)
  def register(self,name,URI):
    return self.__remoteinvoc('register',0,_expandName(name),URI)
  def resolve(self,name):
    return self.__remoteinvoc('resolve',0,_expandName(name))
  def flatlist(self):
    return self.__remoteinvoc('flatlist',0)
  def unregister(self,name):
    return self.__remoteinvoc('unregister',0,_expandName(name))
  def createGroup(self,gname):
    return self.__remoteinvoc('createGroup',0,_expandName(gname))
  def deleteGroup(self,gname):
    return self.__remoteinvoc('deleteGroup',0,_expandName(gname))
  def list(self,gname):
    return self.__remoteinvoc('list',0,_expandName(gname))
  def setMeta(self, name, meta):
    return self.__remoteinvoc('setMeta',0,_expandName(name),meta)
  def getMeta(self, name):
    return self.__remoteinvoc('getMeta',0,_expandName(name))
  def fullName(self,name):
    return _expandName(name)
  def _shutdown(self):
    return self.__remoteinvoc('_shutdown',0)
  def _setSystemMeta(self, name, meta):
    return self.__remoteinvoc('_setSystemMeta',0,_expandName(name),meta)
  def _getSystemMeta(self, name):
    return self.__remoteinvoc('_getSystemMeta',0,_expandName(name))
  def _setIdentification(self, ident):
    self.adapter.setIdentification(ident)
  def _resync(self, twinProxy):
    return self.adapter.remoteInvocation('_resync',0,twinProxy)
  def _synccall(self, *args):
    self.adapter.remoteInvocation('_synccall',Pyro.constants.RIF_Varargs, args)
  def _transferThread(self, newOwnerThread=None):
    pass # dummy function to retain API compatibility with Pyro 3.7
  def __copy__(self):
    # return a Non-connected copy of ourselves)
    proxyCopy = NameServerProxy(self.URI, noconnect=1)
    proxyCopy.adapter.setIdentification(self.adapter.getIdentification(), munge=False)   # copy identification info
    return proxyCopy
  def __deepcopy__(self, arg):
    raise Pyro.errors.PyroError("cannot deepcopy a nameserver proxy")
  def __getstate__(self):
    # for pickling, return a non-connected copy of ourselves:
    copy = self.__copy__()
    copy._release()
    return copy.__dict__
  def __setstate__(self, args):
    # this appears to be necessary otherwise pickle won't work
    self.__dict__=args
        

# Can be used to expand names to absolute names (NS proxy uses this)
# but user code should use the fullName method of the proxy.
def _expandName(name):
  if Pyro.config.PYRO_NS_DEFAULTGROUP[0]!=':':
    raise Pyro.errors.NamingError('default group name is not absolute')
  if name:
    if name[0]==':':
      return name
    return Pyro.config.PYRO_NS_DEFAULTGROUP+'.'+name
  else:
    return Pyro.config.PYRO_NS_DEFAULTGROUP


#############################################################################
#
#  The Name Server (a Pyro Object).
#
#  It has more methods than the ones available in the proxy (above)
#  but that is because the other methods are private and for internal
#  use only.
#
#############################################################################


class NameServer(Pyro.core.ObjBase):
  def __init__(self, role=Pyro.constants.NSROLE_SINGLE, identification=None):
    Pyro.core.ObjBase.__init__(self)
    self.root=NamedTree('<root>')
    self.lock=Pyro.util.getLockObject()
    self.role=role
    self.otherNS=None
    self.ignoreShutdown=False
    if role in (Pyro.constants.NSROLE_PRIMARY, Pyro.constants.NSROLE_SECONDARY):
      # for paired mode with identification, we need to remember the ident string
      adapter=Pyro.protocol.getProtocolAdapter("PYRO")
      adapter.setIdentification(identification)
      self.identification=adapter.getIdentification() # grab the munged ident
    # create default groups
    self.createGroup(':'+'Pyro')
    self.createGroup(Pyro.config.PYRO_NS_DEFAULTGROUP)
    Log.msg("NameServer","Running in",
     {Pyro.constants.NSROLE_SINGLE:"single",
      Pyro.constants.NSROLE_PRIMARY:"primary",
      Pyro.constants.NSROLE_SECONDARY:"secondary"}[self.role],"mode" )
      
  def _initialResyncWithTwin(self, twinProxy):
    if twinProxy:
      try:
        Log.msg("NameServer","Initial resync with other NS at",twinProxy.URI.address,"port",twinProxy.URI.port)
        print "Initial Resync with other NS at",twinProxy.URI.address,"port",twinProxy.URI.port
        # keep old NS (self) registration
        oldNSreg=self.resolve(Pyro.constants.NAMESERVER_NAME)
        proxyForMe=NameServerProxy(self.getProxy().URI,noconnect=1)
        proxyForMe.adapter.setIdentification(self.identification,munge=False) # set pre-munged ident
        self.root=twinProxy._resync(proxyForMe)
        # reset self registration
        try:
          self.unregister(Pyro.constants.NAMESERVER_NAME)
        except:
          pass
        self.register(Pyro.constants.NAMESERVER_NAME,oldNSreg)
        self.otherNS=twinProxy
        Log.msg("NameServer","database sync complete.")
        print "Database synchronized."
      except Pyro.errors.NamingError,x:
        print x
        raise
      
  def _removeTwinNS(self):
    self.otherNS=None
      
  def register(self,name,URI):
    (origname,name)=name,self.validateName(name)
    URI=self.validateURI(URI)
    self.lock.acquire()
    try:
      (group, name)=self.locateGrpAndName(name)
      if len(name or "")<1:
        raise Pyro.errors.NamingError('invalid name',origname)
      if isinstance(group,NameValue):
        raise Pyro.errors.NamingError('parent is no group', group.name)
      try:
        group.newleaf(name,URI)
        Log.msg('NameServer','registered',name,'with URI',str(URI))
        self._dosynccall("register",origname,URI)
      except KeyError:
        Log.msg('NameServer','name already exists:',name)
        raise Pyro.errors.NamingError('name already exists',name)
    finally:
      self.lock.release()

  def unregister(self,name):
    (origname,name)=name,self.validateName(name)
    self.lock.acquire()
    try:
      (group, name)=self.locateGrpAndName(name)
      if len(name or "")<1:
        raise Pyro.errors.NamingError('invalid name',origname)
      try:
        group.cutleaf(name)
        Log.msg('NameServer','unregistered',name)
        self._dosynccall("unregister",origname)
      except KeyError:
        raise Pyro.errors.NamingError('name not found',name)
      except ValueError:
        Log.msg('NameServer','attempt to remove a group:',name)
        raise Pyro.errors.NamingError('is a group, not an object',name)
    finally:
      self.lock.release()

  def resolve(self,name):
    # not thread-locked: higher performance and not necessary.
    name=self.validateName(name)
    try:
      branch=self.getBranch(name)
      if isinstance(branch,NameValue):
        return branch.value
      else:
        Log.msg('NameServer','attempt to resolve groupname:',name)
        raise Pyro.errors.NamingError('attempt to resolve groupname',name)
    except KeyError:
      raise Pyro.errors.NamingError('name not found',name)
    except AttributeError:
      raise Pyro.errors.NamingError('group not found',name)

  def flatlist(self):
    # return a dump
    self.lock.acquire()
    try:
      r=self.root.flatten()
    finally:
      self.lock.release()
    for i in xrange(len(r)):
      r[i]=(':'+r[i][0], r[i][1])
    return r

  def ping(self):
    # Just accept a remote invocation.
    # This method is used to check if NS is still running,
    # and also by the locator if a direct lookup is needed.
    pass

  # --- sync support (twin NS)
  def _resync(self, twinProxy):
    if self.role!=Pyro.constants.NSROLE_SINGLE:
      Log.msg("NameServer","resync requested from NS at",twinProxy.URI.address,"port",twinProxy.URI.port)
      print "Resync requested from NS at",twinProxy.URI.address,"port",twinProxy.URI.port
      self.otherNS=twinProxy
      self.lock.acquire()
      try:
        return self._getSyncDump()
      finally:
        self.lock.release()
    else:
      Log.warn("NameServer","resync requested from",twinProxy.URI,"but not running in correct mode")
      raise Pyro.errors.NamingError("The (other) NS is not running in 'primary' or 'secondary' mode")
  
  # remotely called:
  def _synccall(self, method, *args):
    # temporarily disable the other NS
    oldOtherNS, self.otherNS = self.otherNS, None
    getattr(self, method) (*args)
    self.otherNS = oldOtherNS
    
  def resync(self):
    if self.role==Pyro.constants.NSROLE_SINGLE:
      raise Pyro.errors.NamingError("NS is not running in 'primary' or 'secondary' mode")
    if self.otherNS:
      try:
        self._initialResyncWithTwin(self.otherNS)
        return
      except Exception:
        pass
    raise Pyro.errors.NamingError("cannot resync: twin NS is unknown or unreachable")

  # local helper:
  def _dosynccall(self, method, *args):
    if self.role!=Pyro.constants.NSROLE_SINGLE and self.otherNS:
      try:
        self.otherNS._synccall(method, *args)
      except Exception,x:
        Log.warn("NameServer","ignored error in _synccall - but removing other NS",x)
        self.otherNS=None
    
  # --- hierarchical naming support
  def createGroup(self,groupname):
    groupname=self.validateName(groupname)
    if len(groupname)<2:
      raise Pyro.errors.NamingError('invalid groupname', groupname)
    self.lock.acquire()
    try:
      (parent,name)=self.locateGrpAndName(groupname)
      if isinstance(parent,NameValue):
        raise Pyro.errors.NamingError('parent is no group', groupname)
      try:
        parent.newbranch(name)
        Log.msg('NameServer','created group',groupname)
        self._dosynccall("createGroup",groupname)
      except KeyError:
        raise Pyro.errors.NamingError('group already exists',name)
    finally:
      self.lock.release()

  def deleteGroup(self,groupname):
    groupname=self.validateName(groupname)
    if groupname==':':
      Log.msg('NameServer','attempt to deleteGroup root group')
      raise Pyro.errors.NamingError('not allowed to delete root group')
    self.lock.acquire()
    try:
      (parent,name)=self.locateGrpAndName(groupname)
      try:
        parent.cutbranch(name)
        Log.msg('NameServer','deleted group',name)
        self._dosynccall("deleteGroup",groupname)
      except KeyError:
        raise Pyro.errors.NamingError('group not found',groupname)
      except ValueError:
        raise Pyro.errors.NamingError('is no group',groupname)
    finally:
      self.lock.release()
      
  def list(self,groupname):
    # not thread-locked: higher performance and not necessary.
    if not groupname:
      groupname=':'
    groupname=self.validateName(groupname)
    try:
      return self.getBranch(groupname).list()
    except KeyError:
      raise Pyro.errors.NamingError('group not found',groupname)
    except AttributeError:
      raise Pyro.errors.NamingError('is no group',groupname)
      
  # --- meta info support
  def setMeta(self, name, meta):
    name=self.validateName(name)
    try:
      branch=self.getBranch(name)
      branch.setMeta(meta)
      self._dosynccall("setMeta",name,meta)
    except KeyError:
      raise Pyro.errors.NamingError('name not found',name)
    except AttributeError:
      raise Pyro.errors.NamingError('group not found',name)
  
  def getMeta(self, name):
    name=self.validateName(name)
    try:
      branch=self.getBranch(name)
      return branch.getMeta()
    except KeyError:
      raise Pyro.errors.NamingError('name not found',name)
    except AttributeError:
      raise Pyro.errors.NamingError('group not found',name)

  def _setSystemMeta(self, name, meta):
    name=self.validateName(name)
    try:
      branch=self.getBranch(name)
      branch.setSystemMeta(meta)
      self._dosynccall("_setSystemMeta",name,meta)
    except KeyError:
      raise Pyro.errors.NamingError('name not found',name)
    except AttributeError:
      raise Pyro.errors.NamingError('group not found',name)
  
  def _getSystemMeta(self, name):
    name=self.validateName(name)
    try:
      branch=self.getBranch(name)
      return branch.getSystemMeta()
    except KeyError:
      raise Pyro.errors.NamingError('name not found',name)
    except AttributeError:
      raise Pyro.errors.NamingError('group not found',name)

    # --- shut down the server
  def _shutdown(self):
    if self.ignoreShutdown:
      Log.msg('NameServer','received shutdown request, but shutdown is denied')
      return 'Shutdown request denied'
    else:
      Log.msg('NameServer','received shutdown request, will shutdown shortly')
      self.getDaemon().shutdown()
      return "Will shut down shortly"
        
  # --- private methods follow
  def _getSyncDump(self):
    return self.root

  def locateGrpAndName(self,name):
    # ASSUME name is absolute (from root) (which is required here)
    idx=name.rfind('.')
    if idx>=0:
      # name is hierarchical
      grpname=name[:idx]
      name=name[idx+1:]
      try:
        return (self.getBranch(grpname), name)
      except KeyError:
        raise Pyro.errors.NamingError('(parent)group not found',grpname)
    else:
      # name is in root
      return (self.root, name[1:])

  def getBranch(self,name):
    # ASSUME name is absolute (from root) (which is required here)
    name=name[1:]
    if name:
      return reduce(lambda x,y: x[y], name.split('.'), self.root)
    else:
      return self.root

  def validateName(self,name):
    if name[0]==':':
      if ('' not in name.split('.')):
        for i in name:
          if ord(i)<33 or ord(i)>126 or i=='\\':
            raise Pyro.errors.NamingError('invalid character(s) in name',name)
        return name
      else:
        raise Pyro.errors.NamingError('invalid name',name)
    else:
      # name is not absolute. Make it absolute.
      return _expandName(name)

  def validateURI(self,URI):
    if isinstance(URI, Pyro.core.PyroURI):
      return URI
    try:
      return Pyro.core.PyroURI(URI)
    except:
      raise Pyro.errors.NamingError('invalid URI',URI)

  def publishURI(self, uri, verbose=0):
    # verbose is not used - always prints the uri.
    uri=str(uri)
    print 'URI is:',uri
    try:
      f=open(Pyro.config.PYRO_NS_URIFILE,'w')
      f.write(uri+'\n'); f.close()
      print 'URI written to:',Pyro.config.PYRO_NS_URIFILE
      Log.msg('NameServer','URI written to',Pyro.config.PYRO_NS_URIFILE)
    except:
      Log.warn('NameServer','Couldn\'t write URI to',Pyro.config.PYRO_NS_URIFILE)

#############################################################################
#
#  NamedTree data type. Used for the hierarchical name server.
#
#############################################################################

class NameSpaceSystemMeta(object):
  def __init__(self, node, timestamp, owner):
    self.timestamp=timestamp
    self.owner=owner
    if isinstance(node, NamedTree):
      self.type=0  # tree
    else:
      self.type=1  # leaf
  def __str__(self):
    return "[type="+str(self.type)+" timestamp="+str(self.timestamp)+" owner="+str(self.owner)+"]"

    
# All nodes in the namespace (groups, or namevalue pairs--leafs) have
# a shared set of properties, most notably: meta information.
class NameSpaceNode(object):
  def __init__(self, name, meta, owner):
    self.name=name
    self.systemMeta = NameSpaceSystemMeta(self, time.time(), owner)
    self.userMeta = meta
  def getMeta(self):
    return self.userMeta
  def getSystemMeta(self):
    return self.systemMeta
  def setMeta(self,meta):
    self.userMeta=meta
  def setSystemMeta(self,meta):
    if isinstance(meta, NameSpaceSystemMeta):
      self.systemMeta=meta
    else:
      raise TypeError("system meta info must be NameSpaceSystemMeta object")

class NameValue(NameSpaceNode):
  def __init__(self, name, value=None, meta=None, owner=None):
    NameSpaceNode.__init__(self, name, meta, owner)
    self.value=value

class NamedTree(NameSpaceNode):
  def __init__(self, name, meta=None, owner=None):
    NameSpaceNode.__init__(self, name, meta, owner)
    self.branches={}
  def newbranch(self,name):
    if name in self.branches.keys():
      raise KeyError,'name already exists'
    t = NamedTree(name)
    self.branches[name]=t
    return t
  def newleaf(self,name,value=None):
    if name in self.branches.keys():
      raise KeyError,'name already exists'
    l = NameValue(name,value)
    self.branches[name]=l
    return l
  def cutleaf(self,name):
    if isinstance(self.branches[name], NameValue):
      del self.branches[name]
    else:
      raise ValueError,'not a leaf'
  def cutbranch(self,name):
    if isinstance(self.branches[name], NamedTree):
      del self.branches[name]
    else:
      raise ValueError,'not a branch'
  def __getitem__(self,name):
    return self.branches[name]
  def list(self):
    l=[]
    for (k,v) in self.branches.items():
      if isinstance(v, NamedTree):
        l.append( (k,0) )  # tree
      elif isinstance(v, NameValue):
        l.append( (k,1) )  # leaf
      else:
        raise ValueError('corrupt tree')
    return l
  def flatten(self,prefix=''):
    flat=[]
    for (k,v) in self.branches.items():
      if isinstance(v, NameValue):
        flat.append( (prefix+k, v.value) )
      elif isinstance(v, NamedTree):
        flat.extend(v.flatten(prefix+k+'.'))
    return flat
        

    
#############################################################################
#
#  The Persistent Name Server (a Pyro Object).
#  This implementation uses the hierarchical file system to
#  store the groups (as directories) and objects (as files).
#
#############################################################################

_PNS_META_SUFFIX=".ns_meta"

class PersistentNameServer(NameServer):
  def __init__(self, dbdir=None, role=Pyro.constants.NSROLE_SINGLE, identification=None):
    self.dbroot=os.path.join(Pyro.config.PYRO_STORAGE,dbdir or 'Pyro_NS_database')
    self._initdb_1()
    try:
      NameServer.__init__(self, role=role, identification=identification)
    except Pyro.errors.NamingError:
      pass
    self._initdb_2()

  def _initdb_1(self):
    # root is not a NamedTree but a directory
    try:
      os.mkdir(self.dbroot)
    except OSError,x:
      if x.errno not in (errno.EEXIST, errno.EBUSY):
        raise
  def _initdb_2(self):
    # make sure that the 2 initial groups (Pyro and Default) exist
    try: self.createGroup(':'+'Pyro')
    except Pyro.errors.NamingError: pass
    try: self.createGroup(Pyro.config.PYRO_NS_DEFAULTGROUP)
    except Pyro.errors.NamingError: pass

  def getDBDir(self):
    return self.dbroot

  def _initialResyncWithTwin(self, twinProxy):
    if twinProxy:
      Log.msg("NameServer","Initial resync with other NS at",twinProxy.URI.address,"port",twinProxy.URI.port)
      # keep old NS (self) registration
      oldNSreg=self.resolve(Pyro.constants.NAMESERVER_NAME)
      proxyForMe=NameServerProxy(self.getProxy().URI,noconnect=1)
      proxyForMe.adapter.setIdentification(self.identification,munge=False) # set pre-munged ident
      syncdump=twinProxy._resync(proxyForMe)
      self.otherNS = None   # temporarily disable twin NS ref
      # clear the old database
      Log.msg("NameServer","erasing old database",self.dbroot)
      shutil.rmtree(self.dbroot)
      self._initdb_1()   # phase 2 (creation of default groups) is not needed here
      Log.msg("NameServer","store sync database")
      for group,smeta,umeta in syncdump[0]:
        try:
          if group!=':':
            dirnam = self.translate(group)
            os.mkdir(dirnam)
          if smeta:
            self._setSystemMeta(group,smeta)
          if umeta:
            self.setMeta(group,umeta)
        except EnvironmentError,x:
          Log.warn("NameServer","problem creating group",group,x)
      for name,uri,smeta,umeta in syncdump[1]:
        try:
          origname,name=name,self.validateName(name)
          fn=self.translate(name)
          open(fn,'w').write(uri+'\n')
          if smeta:
            self._setSystemMeta(name,smeta)
          if umeta:
            self.setMeta(name,umeta)
        except Pyro.errors.NamingError,x:
          Log.warn("NameServer","problem registering name",name,x)
      # reset registration of self
      try:
        self.unregister(Pyro.constants.NAMESERVER_NAME)
      except:
        pass
      self.register(Pyro.constants.NAMESERVER_NAME,oldNSreg)
      self.otherNS=twinProxy
      Log.msg("NameServer","database sync complete.")
      print "Database synchronized."

  def register(self,name,URI):
    origname,name=name,self.validateName(name)
    URI=self.validateURI(URI)
    fn=self.translate(name)
    self.lock.acquire()
    try:
      if os.access(fn,os.R_OK):
        Log.msg('NameServer','name already exists:',name)
        raise Pyro.errors.NamingError('name already exists',name)
      try:
        open(fn,'w').write(str(URI)+'\n')
        self._dosynccall("register",origname,URI)
        Log.msg('NameServer','registered',name,'with URI',str(URI))
      except IOError,x:
        if x.errno==errno.ENOENT:
          raise Pyro.errors.NamingError('(parent)group not found')
        elif x.errno==errno.ENOTDIR:
          raise Pyro.errors.NamingError('parent is no group')
        else:
          raise Pyro.errors.NamingError(str(x))
    finally:
      self.lock.release()

  def unregister(self,name):
    origname,name=name,self.validateName(name)
    fn=self.translate(name)
    self.lock.acquire()
    try:
      try:
        os.remove(fn)
        self._dosynccall("unregister",origname)
        Log.msg('NameServer','unregistered',name)
      except OSError,x:
        if x.errno==errno.ENOENT:
          raise Pyro.errors.NamingError('name not found',name)
        elif x.errno==errno.EISDIR:
          Log.msg('NameServer','attempt to remove a group:',name)
          raise Pyro.errors.NamingError('is a group, not an object',name)
        else:
          raise Pyro.errors.NamingError(str(x))
    finally:
      self.lock.release()
      
  def resolve(self,name):
    # not thread-locked: higher performance and not necessary.
    name=self.validateName(name)
    fn = self.translate(name)
    try:
      return Pyro.core.PyroURI(open(fn).read())
    except IOError,x:
      if x.errno==errno.ENOENT:
        raise Pyro.errors.NamingError('name not found',name)
      elif x.errno==errno.EISDIR:
        Log.msg('NameServer','attempt to resolve groupname:',name)
        raise Pyro.errors.NamingError('attempt to resolve groupname',name)
      else:
        raise Pyro.errors.NamingError(str(x))

  def flatlist(self):
    dbroot=self.translate(':')
    self.lock.acquire()
    try:
      flat=[]
      for f in self._filelist(dbroot,dbroot):
        f=self._unescapefilename(f)
        flat.append((f, self.resolve(f)))
      return flat
    finally:
      self.lock.release()

  # --- hierarchical naming support
  def createGroup(self,groupname):
    groupname=self.validateName(groupname)
    dirnam = self.translate(groupname)
    self.lock.acquire()
    try:
      try:
        os.mkdir(dirnam)
        self._dosynccall("createGroup",groupname)
        Log.msg('NameServer','created group',groupname)
      except OSError,x:
        if x.errno in (errno.EEXIST, errno.EBUSY):
          raise Pyro.errors.NamingError('group already exists',groupname)
        elif x.errno == errno.ENOENT:
          raise Pyro.errors.NamingError('(parent)group not found')
        else:
          raise Pyro.errors.NamingError(str(x))
    finally:
      self.lock.release()

  def deleteGroup(self,groupname):
    groupname=self.validateName(groupname)
    if groupname==':':
      Log.msg('NameServer','attempt to deleteGroup root group')
      raise Pyro.errors.NamingError('not allowed to delete root group')
    dirnam = self.translate(groupname)
    self.lock.acquire()
    try:
      if not os.access(dirnam,os.R_OK):
        raise Pyro.errors.NamingError('group not found',groupname)
      try:
        shutil.rmtree(dirnam)
        self._dosynccall("deleteGroup",groupname)
        Log.msg('NameServer','deleted group',groupname)
      except OSError,x:
        if x.errno==errno.ENOENT:
          raise Pyro.errors.NamingError('group not found',groupname)
        elif x.errno==errno.ENOTDIR:
          raise Pyro.errors.NamingError('is no group',groupname)
        else:
          raise Pyro.errors.NamingError(str(x))
    finally:
      self.lock.release()
      
  def list(self,groupname):
    if not groupname:
      groupname=':'
    groupname=self.validateName(groupname)
    dirnam=self.translate(groupname)
    self.lock.acquire()
    try:
      if os.access(dirnam,os.R_OK):
        if os.path.isfile(dirnam):
          raise Pyro.errors.NamingError('is no group',groupname)
        else:
          l = dircache.listdir(dirnam)
          entries = []
          for e in l:
            if e.endswith(_PNS_META_SUFFIX):
              continue
            else:
              objname=self._unescapefilename(e)
              if os.path.isdir(os.path.join(dirnam,e)):
                entries.append((objname,0))    # dir has code 0
              else:
                entries.append((objname,1))    # leaf has code 1
          return entries
      raise Pyro.errors.NamingError('group not found',groupname)
    finally:
      self.lock.release()


  # --- private methods follow
  
  def _getSyncDump(self):
    def visitor(arg,dirname,names):
      shortdirname=dirname[len(self.dbroot)+len(os.path.sep):]
      if shortdirname.endswith(_PNS_META_SUFFIX):
        return
      name = ':'+shortdirname.replace(os.path.sep,'.')
      smeta=self._getSystemMeta(name)
      umeta=self.getMeta(name)
      arg[0].append( (name, smeta,umeta) )
      for n in names:
        if n.endswith(_PNS_META_SUFFIX):
          continue
        n=os.path.join(dirname,n)
        if os.path.isfile(n):
          v=open(n,'r').read().strip()
          name=':'+(n[len(self.dbroot)+len(os.path.sep):]).replace(os.path.sep,'.')
          smeta=self._getSystemMeta(name)
          umeta=self.getMeta(name)
          arg[1].append( (name, v, smeta,umeta) )
    result=( [], [] )   # (groups, names)
    os.path.walk(self.dbroot, visitor, result)
    return result

  def _unescapefilename(self, name):
    parts=name.split('\\')
    res=[parts[0]]
    myappend=res.append
    del parts[0]
    for item in parts:
      if item[1:2]:
        try:
          myappend(chr(int(item[:2], 16)) + item[2:])
        except ValueError:
          myappend('\\' + item)
      else:
        myappend('\\' + item)
    return "".join(res)
  def _escapefilename(self,name):
    name=name.replace(os.path.sep,'\\%02x' % ord(os.path.sep)) # escape path separators in the name
    name=name.replace(':','\\%02x' % ord(':')) # also get rid of any ':' 's
    return name
    
  # recursive file listing, output is like "find <path> -type f"
  # but using NS group separator chars
  def _filelist(self,root,path):
    try:
      (filez,dirz) = Pyro.util.listdir(path)
    except OSError:
      raise Pyro.errors.NamingError('group not found')
      
    files=[]
    for f in filez:
      if f.endswith(_PNS_META_SUFFIX):
        continue
      elif path==root:
        files.append(':'+f)
      else:
        p=path[len(root):].replace(os.sep, '.')
        files.append(':'+p+'.'+f)
    for d in dirz:
      files.extend(self._filelist(root,os.path.join(path,d)))
    return files

  # Pyro NS name to filesystem path translation
  def translate(self,name):
    if name[0]==':':
      name=name[1:]
    name=self._escapefilename(name)
    args=[self.dbroot]+name.split('.')
    return os.path.join(*args)

  def getBranch(self,name):
    tr = self.translate(name)
    if os.path.exists(tr):
      return PersistentNameSpaceNode(filename=tr+_PNS_META_SUFFIX)
    else:
      raise Pyro.errors.NamingError('name not found',name)

# XXX this is a bit of a hack. Only metadata is stored here,
# and it's only used from getBranch, which in turn is only used
# from the set/get meta functions.
class PersistentNameSpaceNode(NameSpaceNode):
  def __init__(self, filename, name=None, meta=None, owner=None):
    NameSpaceNode.__init__(self, name, meta, owner)
    self.filename=filename
    if not name:
      # print "INIT PERSISTENT NODE FROM FILE",self.filename
      # init from file
      try:
        (sysmeta, usermeta)=Pyro.util.getPickle().load(open(self.filename,"rb"))
        NameSpaceNode.setSystemMeta(self, sysmeta)
        NameSpaceNode.setMeta(self, usermeta)
      except Exception:
        pass # just use empty meta...
    else:
      # write to file
      self._writeToFile()
  def setMeta(self,meta):
    NameSpaceNode.setMeta(self, meta)
    self._writeToFile()
  def setSystemMeta(self,meta):
    NameSpaceNode.setSystemMeta(self, meta)
    self._writeToFile()
  def _writeToFile(self):
    # print "WRITE PERSISTENT NODE TO FILE",self.filename
    Pyro.util.getPickle().dump( (self.getSystemMeta(), self.getMeta()) , open(self.filename,"wb"), Pyro.config.PYRO_PICKLE_FORMAT)
    

    
#############################################################################
#
# The broadcast server which listens to broadcast requests of clients who
# want to discover our location, or send other system commands.
#
#############################################################################


class BroadcastServer(SocketServer.UDPServer):

  nameServerURI = ''  # the Pyro URI of the Name Server

  def __init__(self, addr, bcRequestHandler,norange=0):
    if norange:
      portrange=1
    else:
      portrange=Pyro.config.PYRO_PORT_RANGE
    (location,port)=addr
    for port in range(port, port+portrange):
      try:
        SocketServer.UDPServer.__init__(self, (location,port), bcRequestHandler)
        return      # got it!
      except socket.error:
        continue    # try the next port in the list
    raise    # port range exhausted... re-raise the socket error.
    
  def server_activate(self):
    self.requestValidator=lambda x,y: 1  # default: accept all
    self.shutdown=0        # should the server loop stop?
    self.preferredTimeOut=3.0  # preferred timeout for the server loop
      
  def setNS_URI(self,URI):
    self.nameServerURI=str(URI)
  def setRequestValidator(self, validator):
    self.requestValidator=validator
  def keepRunning(self, keep):
    self.ignoreShutdown = keep  # ignore shutdown requests (i.e. keep running?)

  def bcCallback(self,ins):
    for i in ins:
      i.handle_request()

  def verify_request(self, req, addr):
    return self.requestValidator(req, addr)

  def getServerSocket(self):
    return self.socket
  
    
class bcRequestHandler(SocketServer.BaseRequestHandler):
  def handle(self):
    Log.msg('BroadcastServer','incoming request from',str(self.client_address[0]))
    # request is a simple string
    cmd = self.request[0]
    if cmd==NS_SYSCMD_LOCATION:
      # somebody wants to know our location, give them our URI
      self.request[1].sendto(self.server.nameServerURI,self.client_address)
    elif cmd==NS_SYSCMD_SHUTDOWN:
      # we should die!?
      if self.server.ignoreShutdown:
        Log.msg('BroadcastServer','Shutdown ignored.')
        self.request[1].sendto('Shutdown request denied',self.client_address)
      else:
        Log.msg('BroadcastServer','Shutdown received.')
        print 'BroadcastServer received shutdown request... will shutdown shortly...'
        self.request[1].sendto('Will shut down shortly',self.client_address)
        self.server.shutdown=1
    else:
      Log.warn('BroadcastServer','Invalid command ignored:',cmd)

# The default BC request validator... accepts everything
# You must subclass this for your own validators
class BCReqValidator(object):
  def __call__(self, req, addr):
    (cmd,self.sock)=req
    self.addr=addr
    if cmd==NS_SYSCMD_LOCATION:
      return self.acceptLocationCmd()
    elif cmd==NS_SYSCMD_SHUTDOWN:
      return self.acceptShutdownCmd()
    else:
      return 0
  def reply(self,msg):
    self.sock.sendto(msg,self.addr)
  def acceptLocationCmd(self):
    return 1
  def acceptShutdownCmd(self):
    return 1


#############################################################################

class NameServerStarter(object):
  def __init__(self, identification=None):
    Pyro.core.initServer()
    self.identification=identification
    self.started = Pyro.util.getEventObject()
  def start(self, *args, **kwargs):      # see _start for allowed arguments
    kwargs["startloop"]=1
    self._start( *args, **kwargs )
  def initialize(self, *args, **kwargs):    # see _start for allowed arguments
    kwargs["startloop"]=0
    self._start( *args, **kwargs )
  def getServerSockets(self):
    result=self.daemon.getServerSockets()
    if self.bcserver:
      result.append(self.bcserver.getServerSocket())
    return result
  def waitUntilStarted(self,timeout=None):
    self.started.wait(timeout)
    return self.started.isSet()
  def _start(self,hostname=None, nsport=None, bcport=0, keep=0, persistent=0, dbdir=None, Guards=(None,None), allowmultiple=0, dontlookupother=0, verbose=0, startloop=1, role=(Pyro.constants.NSROLE_SINGLE,None), bcaddr=None, nobroadcast=False ):
    if nsport is None:
      if role[0]==Pyro.constants.NSROLE_SECONDARY:
        nsport=Pyro.config.PYRO_NS2_PORT
      else:
        nsport=Pyro.config.PYRO_NS_PORT
    if not bcport:
      if role[0]==Pyro.constants.NSROLE_SECONDARY:
        bcport=Pyro.config.PYRO_NS2_BC_PORT
      else:
        bcport=Pyro.config.PYRO_NS_BC_PORT
    if not bcaddr:
      if role[0]==Pyro.constants.NSROLE_SECONDARY:
        bcaddr=Pyro.config.PYRO_NS2_BC_ADDR
      else:
        bcaddr=Pyro.config.PYRO_NS_BC_ADDR
    otherNSuri=None

    try:
      if not dontlookupother:
        retries=Pyro.config.PYRO_BC_RETRIES
        timeout=Pyro.config.PYRO_BC_TIMEOUT
        Pyro.config.PYRO_BC_RETRIES=1
        Pyro.config.PYRO_BC_TIMEOUT=0.7
        try:
          otherNSuri=NameServerLocator().detectNS(bcaddr=bcaddr)
        except Pyro.errors.PyroError:
          pass
        else:
          print 'The Name Server appears to be already running on this segment.'
          print '(host:',otherNSuri.address,' port:',otherNSuri.port,')'
          if allowmultiple:
            print 'WARNING: starting another Name Server in the same segment!'
          elif role[0] in (Pyro.constants.NSROLE_PRIMARY, Pyro.constants.NSROLE_SECONDARY):
            pass
          else:
            msg='Cannot start multiple Name Servers in the same network segment.'
            print msg
            raise Pyro.errors.NamingError(msg)
  
        if role[0]!=Pyro.constants.NSROLE_SINGLE:
          print "Locating twin NameServer."
          # Do this before starting our own daemon, otherwise possible deadlock!
          # This step is done here to make pretty certain that one of both name
          # servers finds the other either *now*, or else later on (below).
          # If we omit this step here, deadlock may occur on the attempt below!
          otherNS = self.locateTwinNS(role, otherNSuri)
          if otherNS:
            print "Found twin NameServer at",otherNS.URI.address,"port",otherNS.URI.port
            role=(role[0], otherNS)
    
        Pyro.config.PYRO_BC_RETRIES=retries
        Pyro.config.PYRO_BC_TIMEOUT=timeout
      daemon = Pyro.core.Daemon(host=hostname, port=nsport,norange=1)
    except Pyro.errors.DaemonError,x:
      print 'The Name Server appears to be already running on this host.'
      print '(or somebody else occupies our port,',nsport,')'
      if hostname:
        print 'It could also be that the address \''+hostname+'\' is not correct.'
      print 'Name Server was not started!'
      raise

    if self.identification:
      daemon.setAllowedIdentifications([self.identification])
      print 'Requiring connection authentication.'
    if Guards[0]:
      daemon.setNewConnectionValidator(Guards[0])

    if persistent:
      ns=PersistentNameServer(dbdir,role=role[0], identification=self.identification)
      daemon.useNameServer(ns)
      NS_URI=daemon.connectPersistent(ns,Pyro.constants.NAMESERVER_NAME)
    else:
      ns=NameServer(role=role[0], identification=self.identification)
      daemon.useNameServer(ns)
      NS_URI=daemon.connect(ns,Pyro.constants.NAMESERVER_NAME)

    self.bcserver=None
    if nobroadcast:
      Log.msg('NS daemon','Not starting broadcast server due to config option')
      if verbose:
        print "Not starting broadcast server."
    else:
      # Try to start the broadcast server. Binding on the magic "<broadcast>"
      # address should work, but on some systems (windows) it doesn't.
      # Therefore we first try "<broadcast>", if that fails, try "".
      # If any address override is in place, use that ofcourse.
      notStartedError=""
      msg = daemon.validateHostnameAndIP()
      if msg:
        Log.msg('NS daemon','Not starting broadcast server because of issue with daemon IP address.')
        if verbose:
          print "Not starting broadcast server."
      else:
        if bcaddr:
          broadcastAddresses=[bcaddr]
        else:
          broadcastAddresses=["<broadcast>", "", "255.255.255.255"]
        for bc_bind in broadcastAddresses:
          try:
            self.bcserver = BroadcastServer((bc_bind,bcport),bcRequestHandler,norange=1)
            break
          except socket.error,x:
            notStartedError += str(x)+" "
        if not self.bcserver:
          print 'Cannot start broadcast server. Is somebody else occupying our broadcast port?'
          print 'The error(s) were:',notStartedError
          print '\nName Server was not started!'
          raise Pyro.errors.NamingError("cannot start broadcast server")
    
        if Guards[1]:
          self.bcserver.setRequestValidator(Guards[1])
        self.bcserver.keepRunning(keep)

    if keep:
      ns.ignoreShutdown=True
      if verbose:
        print 'Will ignore shutdown requests.'
    else:
      ns.ignoreShutdown=False
      if verbose:
        print 'Will accept shutdown requests.'

      print 'Name server listening on:',daemon.sock.getsockname()
      if self.bcserver:
        print 'Broadcast server listening on:',self.bcserver.socket.getsockname()
      message = daemon.validateHostnameAndIP()
      if message:
        print "\nWARNING:",message,"\n"

    if Guards[0] or Guards[1]:
      if verbose:
        print 'Using security plugins:'
      if Guards[0]:
        clazz=Guards[0].__class__
        if verbose:
          print '  NS new conn validator =',clazz.__name__,'from', clazz.__module__, ' ['+sys.modules.get(clazz.__module__).__file__+']'
      elif verbose: print '  default NS new conn validator'
      if Guards[1]:
        clazz=Guards[1].__class__
        if verbose:
          print '  BC request validator  =',clazz.__name__,'from', clazz.__module__, ' ['+sys.modules.get(clazz.__module__).__file__+']'
      elif verbose: print '  default BC request validator'

    ns.publishURI(NS_URI,verbose)

    if self.bcserver:
      self.bcserver.setNS_URI(NS_URI)
    Log.msg('NS daemon','This is the Pyro Name Server.')
    if persistent:
      Log.msg('NS daemon','Persistent mode, database is in',ns.getDBDir())
      if verbose:
        print 'Persistent mode, database is in',ns.getDBDir()
    Log.msg('NS daemon','Starting on',daemon.hostname,'port', daemon.port)
    if self.bcserver:
      Log.msg('NS daemon','Broadcast server on port',bcport)
    else:
      Log.msg('NS daemon','No Broadcast server')

    if role[0]==Pyro.constants.NSROLE_PRIMARY:
      print "Primary",
    elif role[0]==Pyro.constants.NSROLE_SECONDARY:
      print "Secondary",
    print 'Name Server started.'

    # If we run in primary or secondary mode, resynchronize
    # the NS database with the other name server.
    # Try again to look it up if it wasn't found before.
    
    if role[0]!=Pyro.constants.NSROLE_SINGLE:
      if not otherNS:
        # try again to contact the other name server
        print "Locating twin NameServer again."
        otherNS = self.locateTwinNS(role, otherNSuri)
        role=(role[0], otherNS)
      if otherNS:
        # finally got it, resync!
        print "Found twin NameServer at",otherNS.URI.address,"port",otherNS.URI.port
        ns._initialResyncWithTwin(otherNS)

    self.started.set()   # signal that we've started (for external threads)
    
    self.daemon=daemon
    if os.name!="java":
      daemon.setTimeout(20)

    if startloop:
      # I use a timeout here otherwise you can't break gracefully on Windoze
      try:
        if self.bcserver:
          daemon.requestLoop(lambda s=self: not s.bcserver.shutdown,
            self.bcserver.preferredTimeOut,[self.bcserver],self.bcserver.bcCallback)
          if self.bcserver.shutdown:
            self.shutdown(ns)
        else:
          daemon.requestLoop()
      except KeyboardInterrupt:
        Log.warn('NS daemon','shutdown on user break signal')
        print 'Shutting down on user break signal.'
        self.shutdown(ns)
      except:
        try:
          (exc_type, exc_value, exc_trb) = sys.exc_info()
          out = ''.join(traceback.format_exception(exc_type, exc_value, exc_trb)[-5:])
          Log.error('NS daemon', 'Unexpected exception, type',exc_type,
            '\n--- partial traceback of this exception follows:\n',
            out,'\n--- end of traceback')
          print '*** Exception occured!!! Partial traceback:'
          print out
          print '*** Resuming operations...'
        finally:  
          del exc_type, exc_value, exc_trb    # delete frame refs to allow proper GC

      Log.msg('NS daemon','Shut down gracefully.')
      print 'Name Server gracefully stopped.'


  def locateTwinNS(self, role, otherNSuri):
    try:
      retries=Pyro.config.PYRO_BC_RETRIES
      timeout=Pyro.config.PYRO_BC_TIMEOUT
      Pyro.config.PYRO_BC_RETRIES=1
      Pyro.config.PYRO_BC_TIMEOUT=1
      try:
        if role[1]:
          (host,port)=(role[1]+':').split(':')[:2]
          if len(port)==0:
            port=None
          else:
            port=int(port)
          otherNS=NameServerLocator(self.identification).getNS(host,port,trace=0)
        else:
          if otherNSuri:
            otherNS=NameServerLocator(self.identification).getNS(host=otherNSuri.address, port=otherNSuri.port, trace=0)
          else:
            if role[0]==Pyro.constants.NSROLE_PRIMARY:
              port=Pyro.config.PYRO_NS2_BC_PORT
            else:
              port=Pyro.config.PYRO_NS_BC_PORT
            otherNS=NameServerLocator(self.identification).getNS(host=None,port=port,trace=0)
        Log.msg("NameServerStarted","Found twin NS at",otherNS.URI)
        return otherNS
      except Pyro.errors.ConnectionDeniedError,x:
        raise
      except Exception,x:
        print "WARNING: Cannot find twin NS yet: ",x
        Log.msg("NameServerStarter","Cannot find twin NS yet:",x)
        return None
    finally:
      Pyro.config.PYRO_BC_RETRIES=retries
      Pyro.config.PYRO_BC_TIMEOUT=timeout
      

  def handleRequests(self,timeout=None):
    # this method must be called from a custom event loop
    if self.bcserver:
      self.daemon.handleRequests(timeout, [self.bcserver], self.bcserver.bcCallback)
      if self.bcserver.shutdown:
        self.shutdown()
    else:
      self.daemon.handleRequests(timeout)

  def shutdown(self, ns=None):
    if ns:
      # internal shutdown call with specified NS object
      daemon=ns.getDaemon()
    else:
      # custom shutdown call w/o specified NS object, use stored instance
      daemon=self.daemon
      ns=daemon.getNameServer()
      del self.daemon
    ns._removeTwinNS()
    daemon.disconnect(ns) # clean up nicely
    if self.bcserver:
      self.bcserver.shutdown=1
    daemon.shutdown()

def main(argv):
  Args = Pyro.util.ArgParser()
  Args.parse(argv,'hkmrvxn:p:b:c:d:s:i:1:2:')
  if Args.hasOpt('h'):
    print 'Usage: pyro-ns [-h] [-k] [-m] [-r] [-x] [-n hostname] [-p port] [-b bcport] [-c bcaddr]'
    print '          [-i identification] [-d [databasefile]] [-s securitymodule]'
    print '          [-1 [host:port]] [-2 [host:port]] [-v]'
    print '  where -p = NS server port (0 for auto)'
    print '        -n = non-default hostname to bind on'
    print '        -b = NS broadcast port'
    print '        -c = NS broadcast address override'
    print '        -x = do not start a broadcast listener'
    print '        -m = allow multiple instances in network segment'
    print '        -r = don\'t attempt to find already existing nameservers'
    print '        -k = keep running- do not respond to shutdown requests'
    print '        -d = use persistent database, provide optional storage directory'
    print '        -s = use given python module with security plugins'
    print '        -i = specify the required authentication ID'
    print '        -1 = runs this NS as primary, opt. specify where secondary is'
    print '        -2 = runs this NS as secondary, opt. specify where primary is'
    print '        -v = verbose output'
    print '        -h = print this help'
    raise SystemExit
  host = Args.getOpt('n',None)
  port = Args.getOpt('p',None)
  if port:
    port=int(port)
  bcport = int(Args.getOpt('b',0))
  bcaddr = Args.getOpt('c',None)
  nobroadcast = Args.hasOpt('x')
  
  role=Pyro.constants.NSROLE_SINGLE
  roleArgs=None
  if Args.hasOpt('1'):
    role=Pyro.constants.NSROLE_PRIMARY
    roleArgs=Args.getOpt('1')
  if Args.hasOpt('2'):
    role=Pyro.constants.NSROLE_SECONDARY
    roleArgs=Args.getOpt('2')

  ident = Args.getOpt('i',None)
  verbose = Args.hasOpt('v')
  keep=Args.hasOpt('k')
  allowmultiple=Args.hasOpt('m')
  dontlookupother=Args.hasOpt('r')

  try:
    dbdir = Args.getOpt('d')
    persistent = 1
  except KeyError:
    persistent = 0
    dbdir = None

  try:
    secmod = __import__(Args.getOpt('s'),locals(),globals())
    Guards = (secmod.NSGuard(), secmod.BCGuard())
  except ImportError,x:
    print 'Error loading security module:',x
    print '(is it in your python import path?)'
    raise SystemExit
  except KeyError:
    secmod = None
    Guards = (None,None)

  Args.printIgnored()
  if Args.args:
    print 'Ignored arguments:', ' '.join(Args.args)

  print '*** Pyro Name Server ***'
  if ident:
    starter=NameServerStarter(identification=ident)
  else:
    starter=NameServerStarter()

  try:
    starter.start(host,port,bcport,keep,persistent,dbdir,Guards,allowmultiple,dontlookupother,verbose,role=(role,roleArgs),bcaddr=bcaddr,nobroadcast=nobroadcast)
  except (Pyro.errors.NamingError, Pyro.errors.DaemonError),x:
    # this error has already been printed, just exit.
    pass


# allow easy starting of the NS by using python -m
if __name__=="__main__":
  main(sys.argv[1:])
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