--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.7/site-packages/galaxy/util/watcher.py	Sat May 02 07:14:21 2020 -0400
@@ -0,0 +1,190 @@
+# 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__)
+
+
+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
+
+
+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()
+
+
+class BaseWatcher(object):
+
+    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 = {}
+
+    def start(self):
+        if self.observer is None:
+            self.observer = self.observer_class()
+            self.observer.start()
+            self.resume_watching()
+
+    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)
+
+    def resume_watching(self):
+        for dir_path, recursive in self.monitored_dirs.items():
+            self.monitor(dir_path, recursive)
+
+    def shutdown(self):
+        if self.observer is not None:
+            self.observer.stop()
+            self.observer.join()
+            self.observer = None
+
+
+class Watcher(BaseWatcher):
+
+    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)
+
+    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)
+
+    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)
+
+
+class EventHandler(FileSystemEventHandler):
+
+    def __init__(self, watcher):
+        self.watcher = watcher
+
+    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)
+
+
+class NullWatcher(object):
+
+    def start(self):
+        pass
+
+    def shutdown(self):
+        pass
+
+    def watch_file(self, *args, **kwargs):
+        pass
+
+    def watch_directory(self, *args, **kwargs):
+        pass