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#!/usr/bin/env python
import threading
import time
from watchdog.observers.polling import PollingObserver
from dm.common.utility.loggingManager import LoggingManager
from dm.common.utility.configurationManager import ConfigurationManager
from dm.common.objects.observedFile import ObservedFile
from dm.common.utility.singleton import Singleton
from dmFileSystemEventHandler import DmFileSystemEventHandler
from fileProcessingManager import FileProcessingManager
class FileSystemObserver(threading.Thread,Singleton):
CONFIG_SECTION_NAME = 'FileSystemObserver'
MIN_FILE_PROCESSING_DELAY_IN_SECONDS_KEY = 'minfileprocessingdelayinseconds'
FILE_SYSTEM_EVENT_TIMEOUT_IN_SECONDS_KEY = 'filesystemeventtimeoutinseconds'
# Singleton.
__instanceLock = threading.RLock()
__instance = None
def __init__(self):
FileSystemObserver.__instanceLock.acquire()
try:
if FileSystemObserver.__instance:
return
FileSystemObserver.__instance = self
threading.Thread.__init__(self)
self.setName('FileSystemObserverThread')
self.logger = LoggingManager.getInstance().getLogger(self.__class__.__name__)
self.logger.debug('Initializing')
self.lock = threading.RLock()
self.eventFlag = threading.Event()
self.exitFlag = False
self.observedFileMap = {}
self.observer = PollingObserver()
self.eventHandler = DmFileSystemEventHandler(self)
self.observedWatchDict = {}
self.__configure()
self.fileProcessingManager = FileProcessingManager.getInstance()
self.logger.debug('Initialization complete')
finally:
FileSystemObserver.__instanceLock.release()
def __configure(self):
cm = ConfigurationManager.getInstance()
configItems = cm.getConfigItems(FileSystemObserver.CONFIG_SECTION_NAME)
self.logger.debug('Got config items: %s' % configItems)
self.minFileProcessingDelayInSeconds = int(cm.getConfigOption(FileSystemObserver.CONFIG_SECTION_NAME, FileSystemObserver.MIN_FILE_PROCESSING_DELAY_IN_SECONDS_KEY))
self.fileSystemTimeoutInSeconds = int(cm.getConfigOption(FileSystemObserver.CONFIG_SECTION_NAME, FileSystemObserver.FILE_SYSTEM_EVENT_TIMEOUT_IN_SECONDS_KEY))
def startObservingPath(self, path):
self.lock.acquire()
try:
self.logger.debug('Starting observer for %s' % path)
observedWatch = self.observer.schedule(self.eventHandler, path, recursive=True)
self.observedWatchDict[path] = observedWatch
finally:
self.lock.release()
def stopObservingPath(self, path):
self.lock.acquire()
try:
observedWatch = self.observedWatchDict.get(path)
if observedWatch:
self.logger.debug('Stopping observer for %s' % path)
self.observer.unschedule(observedWatch)
else:
self.logger.debug('Observer for %s is not active' % path)
finally:
self.lock.release()
def observedFileUpdated(self, path):
self.lock.acquire()
try:
observedFile = self.observedFileMap.get(path, ObservedFile(path=path))
observedFile.setLastUpdatedTimestampToNow()
self.observedFileMap[path] = observedFile
self.logger.debug('Observed file updated: %s', observedFile)
finally:
self.lock.release()
def checkObservedFilesForProcessing(self):
self.lock.acquire()
try:
now = time.time()
pathsForProcessing = []
for (path,observedFile) in self.observedFileMap.items():
timestamp = observedFile.get('lastUpdateTimestamp')
deltaT = now - timestamp
if deltaT > self.minFileProcessingDelayInSeconds:
self.logger.debug('File %s was last modified %s seconds ago, will process it.' % (path, deltaT))
pathsForProcessing.append(path)
return pathsForProcessing
finally:
self.lock.release()
def processObservedFile(self, path):
self.lock.acquire()
try:
self.logger.debug('Processing file %s' % path)
observedFile = self.observedFileMap.get(path)
if observedFile is not None:
del self.observedFileMap[path]
self.fileProcessingManager.processObservedFile(observedFile)
finally:
self.lock.release()
def start(self):
self.lock.acquire()
try:
self.logger.debug('Starting file observer thread')
threading.Thread.start(self)
self.logger.debug('Starting watchdog observer')
self.observer.start()
finally:
self.lock.release()
def run(self):
self.logger.debug('Starting thread: %s' % self.getName())
while True:
if self.exitFlag:
self.logger.debug('Exit flag set, %s done' % self.getName())
break
try:
self.logger.debug('Checking observed files')
pathsForProcessing = self.checkObservedFilesForProcessing()
for path in pathsForProcessing:
self.processObservedFile(path)
except Exception, ex:
self.logger.exception(ex)
self.eventFlag.wait(timeout=self.fileSystemTimeoutInSeconds)
def stop(self):
self.lock.acquire()
try:
self.logger.debug('Stopping watchdog observer')
self.observer.stop()
self.observer.join()
self.logger.debug('Stopping file observer thread')
self.exitFlag = True
self.eventFlag.set()
self.logger.debug('Event is set, joining thread')
threading.Thread.join(self)
self.logger.debug('Module stopped')
finally:
self.lock.release()
def setEvent(self):
self.lock.acquire()
try:
self.eventFlag.set()
finally:
self.lock.release()
def clearEvent(self):
self.lock.acquire()
try:
self.eventFlag.clear()
finally:
self.lock.release()
####################################################################
# Testing
if __name__ == '__main__':
fp = FileSystemObserver.getInstance()
fp.start()
time.sleep(30)
fp.stop()