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Source code for galaxy.util.watcher

# TODO: this is largely copied from galaxy.tools.toolbox.galaxy and generalized, the tool-oriented watchers in that
# module should probably be updated to use this where possible

from __future__ import absolute_import

import logging
import os.path
import time

from six.moves import filter

try:
    from watchdog.events import FileSystemEventHandler
    from watchdog.observers import Observer
    from watchdog.observers.polling import PollingObserver
    can_watch = True
except ImportError:
    Observer = None
    FileSystemEventHandler = object
    PollingObserver = None
    can_watch = False

from galaxy.util.hash_util import md5_hash_file

log = logging.getLogger(__name__)


[docs]def get_observer_class(config_name, config_value, default, monitor_what_str): """ """ config_value = config_value or default config_value = str(config_value).lower() if config_value in ("true", "yes", "on", "auto"): expect_observer = True observer_class = Observer elif config_value == "polling": expect_observer = True observer_class = PollingObserver elif config_value in ('false', 'no', 'off'): expect_observer = False observer_class = None else: message = "Unrecognized value for %s config option: %s" % (config_name, config_value) raise Exception(message) if expect_observer and observer_class is None: message = "Watchdog library unavailable, cannot monitor %s." % monitor_what_str if config_value == "auto": log.info(message) else: raise Exception(message) return observer_class
[docs]def get_watcher(config, config_name, default="False", monitor_what_str=None, watcher_class=None, event_handler_class=None, **kwargs): config_value = getattr(config, config_name, None) observer_class = get_observer_class(config_name, config_value, default=default, monitor_what_str=monitor_what_str) if observer_class is not None: watcher_class = watcher_class or Watcher event_handler_class = event_handler_class or EventHandler return watcher_class(observer_class, event_handler_class, **kwargs) else: return NullWatcher()
[docs]class BaseWatcher(object):
[docs] def __init__(self, observer_class, even_handler_class, **kwargs): self.observer = None self.observer_class = observer_class self.event_handler = even_handler_class(self) self.monitored_dirs = {}
[docs] def start(self): if self.observer is None: self.observer = self.observer_class() self.observer.start() self.resume_watching()
[docs] def monitor(self, dir_path, recursive=False): self.monitored_dirs[dir_path] = recursive if self.observer is not None: self.observer.schedule(self.event_handler, dir_path, recursive=recursive)
[docs] def resume_watching(self): for dir_path, recursive in self.monitored_dirs.items(): self.monitor(dir_path, recursive)
[docs] def shutdown(self): if self.observer is not None: self.observer.stop() self.observer.join() self.observer = None
[docs]class Watcher(BaseWatcher):
[docs] def __init__(self, observer_class, event_handler_class, **kwargs): super(Watcher, self).__init__(observer_class, event_handler_class, **kwargs) self.path_hash = {} self.file_callbacks = {} self.dir_callbacks = {} self.ignore_extensions = {} self.require_extensions = {} self.event_handler = event_handler_class(self)
[docs] def watch_file(self, file_path, callback=None): file_path = os.path.abspath(file_path) dir_path = os.path.dirname(file_path) if dir_path not in self.monitored_dirs: if callback is not None: self.file_callbacks[file_path] = callback self.monitor(dir_path) log.debug("Watching for changes to file: %s", file_path)
[docs] def watch_directory(self, dir_path, callback=None, recursive=False, ignore_extensions=None, require_extensions=None): dir_path = os.path.abspath(dir_path) if dir_path not in self.monitored_dirs: if callback is not None: self.dir_callbacks[dir_path] = callback if ignore_extensions: self.ignore_extensions[dir_path] = ignore_extensions if require_extensions: self.require_extensions[dir_path] = require_extensions self.monitor(dir_path, recursive=recursive) log.debug("Watching for changes in directory%s: %s", ' (recursively)' if recursive else '', dir_path)
[docs]class EventHandler(FileSystemEventHandler):
[docs] def __init__(self, watcher): self.watcher = watcher
[docs] def on_any_event(self, event): self._handle(event)
def _extension_check(self, key, path): required_extensions = self.watcher.require_extensions.get(key) if required_extensions: return any(filter(path.endswith, required_extensions)) return not any(filter(path.endswith, self.watcher.ignore_extensions.get(key, []))) def _handle(self, event): # modified events will only have src path, move events will # have dest_path and src_path but we only care about dest. So # look at dest if it exists else use src. path = getattr(event, 'dest_path', None) or event.src_path path = os.path.abspath(path) callback = self.watcher.file_callbacks.get(path) if os.path.basename(path).startswith('.'): return if callback: ext_ok = self._extension_check(path, path) else: # reversed sort for getting the most specific dir first for key in reversed(sorted(self.watcher.dir_callbacks.keys())): if os.path.commonprefix([path, key]) == key: callback = self.watcher.dir_callbacks[key] ext_ok = self._extension_check(key, path) break if not callback or not ext_ok: return cur_hash = md5_hash_file(path) if cur_hash: if self.watcher.path_hash.get(path) == cur_hash: return else: time.sleep(0.5) if cur_hash != md5_hash_file(path): # We're still modifying the file, it'll be picked up later return self.watcher.path_hash[path] = cur_hash callback(path=path)
[docs]class NullWatcher(object):
[docs] def start(self): pass
[docs] def shutdown(self): pass
[docs] def watch_file(self, *args, **kwargs): pass
[docs] def watch_directory(self, *args, **kwargs): pass