Coverage for sparts/tasks/file : 88%

# Copyright (c) 2014, Facebook, Inc.  All rights reserved. 

# 

# This source code is licensed under the BSD-style license found in the 

# LICENSE file in the root directory of this source tree. An additional grant 

# of patent rights can be found in the PATENTS file in the same directory. 

# 

"""Tasks related for files and filesystems""" 

from .poller import PollerTask 

import errno 

import os 

from ..sparts import option 

class DirectoryWatcherTask(PollerTask): 

    """DirectoryWatcherTask watches for new, deleted, and modified files 

    The `IGNORE_INITIAL_FILES` attribute can be overridden to Flaase if you 

    do not want to receive a bunch of `onFileCreated` callbacks during startup. 

    This could be better implemented with the inotify/pyinotify API, but for 

    basic rapid prototyping, polling should be sufficient. 

    """ 

    PATH = '.' 

    path = option(default=lambda cls: cls.PATH, 

                  help='Directory path to watch [%(default)s]') 

    IGNORE_INITIAL_FILES = True 

    def onFileCreated(self, filename, stat): 

        """Override this to do custom processing when new files are created.""" 

        self.logger.debug('onFileCreated(%s, %s)', filename, stat) 

    def onFileDeleted(self, filename, old_stat): 

        """Override this to do custom processing when files are deleted.""" 

        self.logger.debug('onFileDeleted(%s, %s)', filename, old_stat) 

    def onFileChanged(self, filename, old_stat, new_stat): 

        """Override this to do custom processing when files are modified.""" 

        self.logger.debug('onFileChanged(%s, %s, %s)', filename, old_stat, new_stat) 

    def fetch(self): 

        """Overridden to stat a particular filesystem path""" 

        d = {} 

        root = self.path 

        contents = self.listdir(root) 

        for name in contents: 

            try: 

                d[name] = self.stat(os.path.join(root, name)) 

            except OSError as e: 

                # There is a race condition between listdir() and stat() where 

                # files might be deleted.  On ENOENT from a stat call, assume 

                # the file is gone.  Raise non-ENOENT exceptions 

54                if e.errno != errno.ENOENT: 

                    raise 

        return sorted(d.items()) 

    def onValueChanged(self, old_value, new_value): 

        """Overridden to track file statuses.""" 

        if old_value is None: 

            # For the first run, ignore pre-existing files by default. 

            # Override this class and set this to False if you want them. 

66            if self.IGNORE_INITIAL_FILES: 

                return 

            old_value = [] 

        old_value_dict = dict(old_value) 

        new_value_dict = dict(new_value) 

        for (name, old_stat) in old_value: 

            if name not in new_value_dict: 

                self.onFileDeleted(name, old_stat) 

            else: 

                new_stat = new_value_dict[name] 

70                if new_stat != old_stat: 

                    self.onFileChanged(name, old_stat, new_stat) 

        for (name, new_stat) in new_value: 

            if name not in old_value_dict: 

                self.onFileCreated(name, new_stat) 

    def listdir(self, path): 

        """Wrapper for making unittesting/mocking easier""" 

        return os.listdir(path) 

    def stat(self, path): 

        """Wrapper for making unittesting/mocking easier""" 

        return os.stat(path)