InotifyDetector.py

__author__ = 'Manuela Kuhn <manuela.kuhn@desy.de>'


import os
import logging
from inotifyx import binding
from inotifyx.distinfo import version as __version__

import helperScript

constants = {}

for name in dir(binding):
    if name.startswith('IN_'):
        globals()[name] = constants[name] = getattr(binding, name)


# Source: inotifyx library code example
# Copyright (c) 2005 Manuel Amador
# Copyright (c) 2009-2011 Forest Bond
class InotifyEvent(object):
    '''
    InotifyEvent(wd, mask, cookie, name)

    A representation of the inotify_event structure.  See the inotify
    documentation for a description of these fields.
    '''

    wd = None
    mask = None
    cookie = None
    name = None

    def __init__(self, wd, mask, cookie, name):
        self.wd = wd
        self.mask = mask
        self.cookie = cookie
        self.name = name

    def __str__(self):
        return '%s: %s' % (self.wd, self.get_mask_description())

    def __repr__(self):
        return '%s(%s, %s, %s, %s)' % (
          self.__class__.__name__,
          repr(self.wd),
          repr(self.mask),
          repr(self.cookie),
          repr(self.name),
        )

    def get_mask_description(self):
        '''
        Return an ASCII string describing the mask field in terms of
        bitwise-or'd IN_* constants, or 0.  The result is valid Python code
        that could be eval'd to get the value of the mask field.  In other
        words, for a given event:

        >>> from inotifyx import *
        >>> assert (event.mask == eval(event.get_mask_description()))
        '''

        parts = []
        for name, value in constants.items():
            if self.mask & value:
                parts.append(name)
        if parts:
            return '|'.join(parts)
        return '0'


# Modification of the inotifyx example found inside inotifyx library
# Copyright (c) 2005 Manuel Amador
# Copyright (c) 2009-2011 Forest Bond
class InotifyDetector():
    paths      = []
    wd_to_path = {}
    fd         = None
    log        = None


    def __init__(self, paths):

        self.paths = paths
        self.log  = self.getLogger()
        self.fd  = binding.init()

        self.add_watch()


    def get_events(self, fd, *args):
        '''
        get_events(fd[, timeout])

        Return a list of InotifyEvent instances representing events read from
        inotify.  If timeout is None, this will block forever until at least one
        event can be read.  Otherwise, timeout should be an integer or float
        specifying a timeout in seconds.  If get_events times out waiting for
        events, an empty list will be returned.  If timeout is zero, get_events
        will not block.
        '''
        return [
          InotifyEvent(wd, mask, cookie, name)
          for wd, mask, cookie, name in binding.get_events(fd, *args)
        ]


    def getLogger(self):
        logger = logging.getLogger("inotifyDetector")
        return logger


    def add_watch(self):
        try:
            for path in self.paths:
                wd = binding.add_watch(self.fd, path)
                self.wd_to_path[wd] = path
                self.log.debug("Register watch for path:" + str(path) )
        except Exception as e:
            self.log.error("Could not register watch for path: " + str(path) )
            self.log.debug("Error was " + str(e))
            self.stop()


    def getNewEvent(self):

        eventMessageList = []
        eventMessage = {}

        events = self.get_events(self.fd)
        for event in events:
            path = self.wd_to_path[event.wd]
            parts = [event.get_mask_description()]
            parts = event.get_mask_description()
            parts_array = parts.split("|")

            if not event.name:
                return []

            is_dir     = ("IN_ISDIR" in parts_array)
            is_closed  = ("IN_CLOSE" in parts_array or "IN_CLOSE_WRITE" in parts_array)
            is_created = ("IN_CREATE" in parts_array)

            # if a new directory is created inside the monitored one,
            # this one has to be monitored as well
            if is_created and is_dir and event.name:
                dirname =  path + os.sep + event.name
                if dirname in self.paths:
                    self.log.debug("Directory already contained in path list: " + str(dirname))
                else:
                    wd = binding.add_watch(self.fd, dirname)
                    self.wd_to_path[wd] = dirname
                    self.log.info("Added new directory to watch:" + str(dirname))

            # only closed files are send
            if is_closed and not is_dir:
                parentDir    = path
                relativePath = ""
                eventMessage = {}

                if parentDir not in self.paths:
                    (parentDir,relDir) = os.path.split(parentDir)
                    relativePath += os.sep + relDir
                else:
                    # the event for a file /tmp/test/source/local/file1.tif is of the form:
                    # {
                    #   "sourcePath" : "/tmp/test/source/"
                    #   "relativePath": "local"
                    #   "filename"   : "file1.tif"
                    # }
                    eventMessage = {
                            "sourcePath"  : parentDir,
                            "relativePath": relativePath,
                            "filename"    : event.name
                            }
                    eventMessageList.append(eventMessage)

        return eventMessageList



    def process(self):
        try:
            try:
                while True:
                    self.getNewEvent()
            except KeyboardInterrupt:
                pass
        finally:
            self.stop()


    def stop(self):

        try:
            try:
                for wd in self.wd_to_path:
                    binding.rm_watch(self.fd, wd)
            except Exception as e:
                    self.log.error("Unable to remove watch.")
                    self.log.debug("Error was: " + str(e))
        finally:
            os.close(self.fd)




if __name__ == '__main__':
    logfilePath = "/tmp/log/inotifyDetector.log"

    #enable logging
    helperScript.initLogging(logfilePath, verbose)