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path: root/src/lib/Server/FileMonitor.py
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import logging
import os
import stat
from time import sleep, time

logger = logging.getLogger('Bcfg2.Server.FileMonitor')

def ShouldIgnore(event):
    '''Test if the event should be suppresed'''
    # FIXME should move event suppression out of the core
    if event.filename.split('/')[-1] == '.svn':
        return True
    if event.filename.endswith('~') or event.filename.endswith('.tmp') \
    or event.filename.startswith('#') or event.filename.startswith('.#'):
        #logger.error("Suppressing event for file %s" % (event.filename))
        return True
    return False

class Event(object):
    def __init__(self, request_id, filename, code):
        self.requestID = request_id
        self.filename = filename
        self.action = code

    def code2str(self):
        '''return static code for event'''
        return self.action


class GaminEvent(Event):
    '''
       This class provides an event analogous to
       python-fam events based on gamin sources
    '''
    def __init__(self, request_id, filename, code):
        Event.__init__(self, request_id, filename, code)
        action_map = {GAMCreated: 'created', GAMExists: 'exists',
                      GAMChanged: 'changed', GAMDeleted: 'deleted',
                      GAMEndExist: 'endExist', GAMMoved: 'moved'}
        if code in action_map:
            self.action = action_map[code]

class FileMonitor(object):
    '''File Monitor baseclass'''
    def __init__(self, debug=False):
        object.__init__(self)
        self.debug = debug
        self.handles = dict()

    def fileno(self):
        return 0

    def handle_one_event(self, event):
        if ShouldIgnore(event):
            return
        if event.requestID not in self.handles:
            logger.info("Got event for unexpected id %s, file %s" %
                        (event.requestID, event.filename))
            return
        if self.debug:
            logger.info("Dispatching event %s %s to obj %s" \
                        % (event.code2str(), event.filename,
                           self.handles[event.requestID]))
        try:
            self.handles[event.requestID].HandleEvent(event)
        except:
            logger.error("error in handling of gamin event for %s" % \
                         (event.filename), exc_info=1)

    def handle_event_set(self, lock=None):
        count = 1
        event = self.get_event()
        start = time()
        if lock:
            lock.acquire()
        try:
            self.handle_one_event(event)
            while self.pending():
                self.handle_one_event(self.get_event())
                count += 1
        except:
            pass
        if lock:
            lock.release()
        end = time()
        logger.info("Handled %d events in %.03fs" % (count, (end-start)))

    def handle_events_in_interval(self, interval):
        start = time()
        end = start + interval
        while time() < end:
            if self.pending():
                self.handle_event_set()
            else:
                sleep(0.5)

class Fam(FileMonitor):
    '''
       The fam object is a set of callbacks for
       file alteration events (FAM support)
    '''
    
    def __init__(self, debug=False):
        FileMonitor.__init__(self, debug)
        self.fm = _fam.open()

    def fileno(self):
        return self.fm.fileno()

    def AddMonitor(self, path, obj):
        '''add a monitor to path, installing a callback to obj.HandleEvent'''
        mode = os.stat(path)[stat.ST_MODE]
        if stat.S_ISDIR(mode):
            handle = self.fm.monitorDirectory(path, None)
        else:
            handle = self.fm.monitorFile(path, None)
        if obj != None:
            self.handles[handle.requestID()] = obj
        return handle.requestID()

    def pending(self):
        return self.fm.pending()

    def get_event(self):
        return self.fm.nextEvent()

class Gamin(FileMonitor):
    '''
       The fam object is a set of callbacks for
       file alteration events (Gamin support)
    '''
    def __init__(self, debug=False):
        FileMonitor.__init__(self, debug)
        self.mon = WatchMonitor()
        self.counter = 0
        self.events = []

    def fileno(self):
        return self.mon.get_fd()

    def queue(self, path, action, request_id):
        '''queue up the event for later handling'''
        self.events.append(GaminEvent(request_id, path, action))

    def AddMonitor(self, path, obj):
        '''add a monitor to path, installing a callback to obj.HandleEvent'''
        handle = self.counter
        self.counter += 1
        mode = os.stat(path)[stat.ST_MODE]
        if stat.S_ISDIR(mode):
            self.mon.watch_directory(path, self.queue, handle)
        else:
            self.mon.watch_file(path, self.queue, handle)
        self.handles[handle] = obj
        return handle

    def pending(self):
        return self.mon.event_pending()

    def get_event(self):
        self.mon.handle_one_event()
        return self.events.pop()

class Pseudo(FileMonitor):
    '''
       The fam object is a set of callbacks for
       file alteration events (static monitor support)
    '''
    
    def __init__(self, debug=False):
        FileMonitor.__init__(self, debug=False)
        self.pending_events = []

    def pending(self):
        return len(self.pending_events) != 0

    def get_event(self):
        return self.pending_events.pop()

    def AddMonitor(self, path, obj):
        '''add a monitor to path, installing a callback to obj.HandleEvent'''
        handleID = len(self.handles.keys())
        mode = os.stat(path)[stat.ST_MODE]
        handle = GaminEvent(handleID, path, 'exists')
        if stat.S_ISDIR(mode):
            dirList = os.listdir(path)
            self.pending_events.append(handle)
            for includedFile in dirList:
                self.pending_events.append(Event(handleID, includedFile, 'exists'))
            self.pending_events.append(Event(handleID, path, 'endExist'))
        else:
            self.pending_events.append(Event(handleID, path, 'exists'))
        if obj != None:
            self.handles[handleID] = obj
        return handleID


available = {}
try:
    from gamin import WatchMonitor, GAMCreated, GAMExists, GAMEndExist, GAMChanged, GAMDeleted, GAMMoved
    available['gamin'] = Gamin
except ImportError:
    # fall back to _fam
    pass
try:
    import _fam
    available['fam'] = Fam
except ImportError:
    pass
available['pseudo'] = Pseudo

for fdrv in ['gamin', 'fam', 'pseudo']:
    if fdrv in available:
        available['default'] = available[fdrv]
        break