fsMonitorServer.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
    OMERO.fs MonitorServer module.

    Copyright 2009 University of Dundee. All rights reserved.
    Use is subject to license terms supplied in LICENSE.txt

"""
import logging
import sys, traceback
import socket

import omero_ext.uuid as uuid # see ticket:3774

try:
    from hashlib import sha1 as sha
except:
    from sha import sha

# Third party path package. It provides much of the 
# functionality of os.path but without the complexity.
# Imported as pathModule to avoid potential clashes.
import path as pathModule

from fsMonitor import MonitorFactory

import omero.all
import omero.grid.monitors as monitors


class MonitorServerI(monitors.MonitorServer):
    """
        Co-ordinates a number of Monitors
        
        :group Constructor: __init__
        :group Methods exposed in Slice: createMonitor, startMonitor, stopMonitor, destroyMonitor,
            getMonitorState
        :group Other methods: _getNextMonitorId, callback
        
    """
    def __init__(self):
        """
            Intialise the instance variables.
        
        """
        self.log = logging.getLogger("fsserver."+__name__)
        #self.fsPrefix = 'omero-fs://' + socket.gethostbyname(socket.gethostname())
        #self.prefixLne = len(self.fsPrefix) ## Save calculating it each time?
        #: Numerical component of a Monitor Id
        self.monitorId = 0
        #: Dictionary of Monitors by Id
        self.monitors = {}
        #: Dictionary of MonitorClientI proxies by Id
        self.proxies = {}


    """
        Methods published in the slice interface omerofs.ice
    
    """
    def createMonitor(self, mType, eTypes, pMode, pathString, whitelist, blacklist, timeout, blockSize, ignoreSysFiles, ignoreDirEvents, proxy, current=None):
        """
            Create a the Monitor for a given path.
        
            :Parameters:
                mType : 
                    The type of monitor.
                    
                eTypes : 
                    A list of the event types to be monitored.          
                    
                pMode : 
                    The mode of directory monitoring: flat, recursive or following.

                pathString : string
                    A string representing a path to be monitored.
                  
                whitelist : list<string>
                    A list of extensions of interest.
                    
                blacklist : list<string>
                    A list of subdirectories to be excluded.

                timeout : float
                    A timeout used by some types of monitor.
                    
                blockSize : intt
                    Number of events to pack into one notification.
                    
                ignoreSysFiles : boolean
                    Flag. If true platform-dependent system files are ignored
                    
                ignoreDirEvents : boolean
                    Flag. If true directory events are ignored
                    
                proxy :
                    A proxy to be informed of events
                    
                current 
                    An ICE context, this parameter is required to be present
                    in an ICE interface method.
                       
            :return: Monitor Id.
            :rtype: string
            
        """
     
        monitorId = self._getNextMonitorId()

        try:
            # blockSize (0) and ignoreDirEvents (True) hardwired until slice is changed.
            self.monitors[monitorId] = MonitorFactory.createMonitor(mType, eTypes, pMode, pathString, 
                                            whitelist, blacklist, timeout, blockSize, 
                                            ignoreSysFiles, ignoreDirEvents, self, monitorId)

        except Exception, e:
            self.log.exception('Failed to create monitor: ')
            raise omero.OmeroFSError(reason='Failed to create monitor: ' + str(e))       

        self.proxies[monitorId] = proxy    

        self.log.info('Monitor id = ' + monitorId + ' created. Proxy: ' + str(proxy))

        return monitorId
    

    def startMonitor(self, id, current=None):
        """
            Start the Monitor with the given Id.
        
            :Parameters:
                id : string
                    A string uniquely identifying a Monitor.
                  
                current 
                    An ICE context, this parameter is required to be present
                    in an ICE interface method.
                       
            :return: Success status.
            :rtype: boolean
            
        """
        try:
            self.monitors[id].start()
            self.log.info('Monitor id = ' + id + ' started')
        except Exception, e:
            self.log.error('Monitor id = ' + id + ' failed to start: ' + str(e))
            raise omero.OmeroFSError(reason='Monitor id = ' + id + ' failed to start: ' + str(e))       
        

    def stopMonitor(self, id, current=None):
        """
            Stop the Monitor with the given Id.
        
            :Parameters:
                id : string
                    A string uniquely identifying a Monitor.
                  
                current 
                    An ICE context, this parameter is required to be present
                    in an ICE interface method.
                       
            :return: Success status.
            :rtype: boolean
            
        """
        try:
            self.monitors[id].stop()
            self.log.info('Monitor id = ' + id + ' stopped')
        except Exception, e:
            self.log.error('Monitor id = ' + id + ' failed to stop: ' + str(e))
            raise omero.OmeroFSError(reason='Monitor id = ' + id + ' failed to stop: ' + str(e))       


    def destroyMonitor(self, id, current=None):
        """
            Destroy the Monitor with the given Id.
        
            :Parameters:
                id : string
                    A string uniquely identifying a Monitor.
                  
                current 
                    An ICE context, this parameter is required to be present
                    in an ICE interface method.
                       
            :return: Success status.
            :rtype: boolean
            
        """
        try:
            del self.monitors[id]
            del self.proxies[id]
            self.log.info('Monitor id = ' + id + ' destroyed')
        except Exception, e:
            self.log.error('Monitor id = ' + id + ' not destroyed: ' + str(e))
            raise omero.OmeroFSError(reason='Monitor id = ' + id + ' not destroyed: ' + str(e))       

    def getMonitorState(self, id):
        """
            Get the state of a monitor.
            
            Return the state of an existing monitor.
            Raise an exception if the monitor does no exist.
        
        """
        self.log.info('Monitor id = ' + id + ' state requested')
        # *****  TO BE IMPLEMENTED  *****
        # If monitor exists return state
        # otherwise raise an exception (no subscription).
        # (and ICE exception implies no server)
        
        raise omero.OmeroFSError('Method not yet implemented.')
        
        
   
    def _getNextMonitorId(self):
        """
            Return next monitor ID and increment.
            
            The monitorID is a unique key to identify a monitor on the
            file system. In the present implementation this is a string 
            generated by uuid.uuid1()
            
            :return: Next monitor Id
            :rtype: string
            
        """
        return str(uuid.uuid1())
        
    def callback(self, monitorId, fileList):
        """
            Callback required by FSEvents.FSEventStream.
        
            :Parameters:

                    
            :return: No explicit return value.
            
        """

        eventList = []
        for fileEvent in fileList:
            info = monitors.EventInfo(fileEvent[0],fileEvent[1])
            eventList.append(info)
              
        proxy = self.proxies[monitorId]
        
        try:
            self.log.info('Event notification on monitor id= %s', monitorId)
            self.log.debug(' ...notifications are: %s', str(eventList))
            proxy.fsEventHappened(monitorId, eventList)
        except Exception, e:
            self.log.info('Callback to monitor id=' + monitorId + ' failed. Reason: ' + str(e))