Add libuv-based watcher

Fixes #821

powerline/lib/watcher/__init__.py

@@ -6,6 +6,7 @@ import sys
 from powerline.lib.watcher.stat import StatFileWatcher
 from powerline.lib.watcher.inotify import INotifyFileWatcher
 from powerline.lib.watcher.tree import TreeWatcher
+from powerline.lib.watcher.uv import UvFileWatcher, UvNotFound
 from powerline.lib.inotify import INotifyError
 
 
@@ -39,6 +40,9 @@ def create_file_watcher(pl, watcher_type='auto', expire_time=10):
 		# Explicitly selected inotify watcher: do not catch INotifyError then.
 		pl.debug('Using requested inotify watcher', prefix='watcher')
 		return INotifyFileWatcher(expire_time=expire_time)
+	elif watcher_type == 'uv':
+		pl.debug('Using requested uv watcher', prefix='watcher')
+		return UvFileWatcher()
 
 	if sys.platform.startswith('linux'):
 		try:
@@ -47,6 +51,12 @@ def create_file_watcher(pl, watcher_type='auto', expire_time=10):
 		except INotifyError:
 			pl.info('Failed to create inotify watcher', prefix='watcher')
 
+	try:
+		pl.debug('Using libuv-based watcher')
+		return UvFileWatcher()
+	except UvNotFound:
+		pl.debug('Failed to import pyuv')
+
 	pl.debug('Using stat-based watcher')
 	return StatFileWatcher()
 

powerline/lib/watcher/tree.py

@@ -7,6 +7,7 @@ from powerline.lib.monotonic import monotonic
 from powerline.lib.inotify import INotifyError
 from powerline.lib.path import realpath
 from powerline.lib.watcher.inotify import INotifyTreeWatcher, DirTooLarge, NoSuchDir, BaseDirChanged
+from powerline.lib.watcher.uv import UvTreeWatcher, UvNotFound
 
 
 class DummyTreeWatcher(object):
@@ -30,6 +31,8 @@ class TreeWatcher(object):
 	def get_watcher(self, path, ignore_event):
 		if self.watcher_type == 'inotify':
 			return INotifyTreeWatcher(path, ignore_event=ignore_event)
+		if self.watcher_type == 'uv':
+			return UvTreeWatcher(path, ignore_event=ignore_event)
 		if self.watcher_type == 'dummy':
 			return DummyTreeWatcher(path)
 		# FIXME
@@ -42,6 +45,10 @@ class TreeWatcher(object):
 				except (INotifyError, DirTooLarge) as e:
 					if not isinstance(e, INotifyError):
 						self.pl.warn('Failed to watch path: {0} with error: {1}'.format(path, e))
+			try:
+				return UvTreeWatcher(path, ignore_event=ignore_event)
+			except UvNotFound:
+				pass
 			return DummyTreeWatcher(path)
 		else:
 			raise ValueError('Unknown watcher type: {0}'.format(self.watcher_type))

powerline/lib/watcher/uv.py

@@ -0,0 +1,167 @@
+# vim:fileencoding=utf-8:noet
+from __future__ import (unicode_literals, absolute_import, print_function)
+
+from powerline.lib.path import realpath
+
+from collections import defaultdict
+from threading import RLock
+from functools import partial
+from threading import Thread
+
+import os
+
+
+class UvNotFound(NotImplementedError):
+	pass
+
+
+pyuv = None
+
+
+def import_pyuv():
+	global pyuv
+	if not pyuv:
+		try:
+			pyuv = __import__('pyuv')
+		except ImportError:
+			raise UvNotFound
+
+
+class UvThread(Thread):
+	daemon = True
+
+	def __init__(self, loop):
+		self.uv_loop = loop
+		super(UvThread, self).__init__()
+
+	def run(self):
+		while True:
+			self.uv_loop.run()
+
+	def join(self):
+		self.uv_loop.stop()
+		return super(UvThread, self).join()
+
+
+_uv_thread = None
+
+
+def start_uv_thread():
+	global _uv_thread
+	if _uv_thread is None:
+		loop = pyuv.Loop()
+		_uv_thread = UvThread(loop)
+		_uv_thread.start()
+	return _uv_thread.uv_loop
+
+
+class UvWatcher(object):
+	def __init__(self):
+		import_pyuv()
+		self.watches = {}
+		self.lock = RLock()
+		self.loop = start_uv_thread()
+
+	def watch(self, path):
+		with self.lock:
+			if path not in self.watches:
+				try:
+					self.watches[path] = pyuv.fs.FSEvent(
+						self.loop,
+						path,
+						partial(self._record_event, path),
+						pyuv.fs.UV_CHANGE | pyuv.fs.UV_RENAME
+					)
+				except pyuv.error.FSEventError as e:
+					code = e.args[0]
+					if code == pyuv.errno.UV_ENOENT:
+						raise OSError('No such file or directory: ' + path)
+					else:
+						raise
+
+	def unwatch(self, path):
+		with self.lock:
+			try:
+				watch = self.watches.pop(path)
+			except KeyError:
+				return
+		watch.close(partial(self._stopped_watching, path))
+
+	def __del__(self):
+		try:
+			lock = self.lock
+		except AttributeError:
+			pass
+		else:
+			with lock:
+				while self.watches:
+					path, watch = self.watches.popitem()
+					watch.close(partial(self._stopped_watching, path))
+
+
+class UvFileWatcher(UvWatcher):
+	def __init__(self):
+		super(UvFileWatcher, self).__init__()
+		self.events = defaultdict(list)
+
+	def _record_event(self, path, fsevent_handle, filename, events, error):
+		with self.lock:
+			self.events[path].append(events)
+			if events | pyuv.fs.UV_RENAME:
+				if not os.path.exists(path):
+					self.watches.pop(path).close()
+
+	def _stopped_watching(self, path, *args):
+		self.events.pop(path, None)
+
+	def __call__(self, path):
+		with self.lock:
+			events = self.events.pop(path, None)
+		if events:
+			return True
+		if path not in self.watches:
+			self.watch(path)
+			return True
+
+
+class UvTreeWatcher(UvWatcher):
+	is_dummy = False
+
+	def __init__(self, basedir, ignore_event=None):
+		super(UvTreeWatcher, self).__init__()
+		self.ignore_event = ignore_event or (lambda path, name: False)
+		self.basedir = realpath(basedir)
+		self.modified = True
+		self.watch_directory(self.basedir)
+
+	def watch_directory(self, path):
+		os.path.walk(path, self.watch_one_directory, None)
+
+	def watch_one_directory(self, arg, dirname, fnames):
+		try:
+			self.watch(dirname)
+		except OSError:
+			pass
+
+	def _stopped_watching(self, path, *args):
+		pass
+
+	def _record_event(self, path, fsevent_handle, filename, events, error):
+		if not self.ignore_event(path, filename):
+			self.modified = True
+			if events == pyuv.fs.UV_CHANGE | pyuv.fs.UV_RENAME:
+				# Stat changes to watched directory are UV_CHANGE|UV_RENAME. It 
+				# is weird.
+				pass
+			elif events | pyuv.fs.UV_RENAME:
+				if not os.path.isdir(path):
+					self.unwatch(path)
+				else:
+					full_name = os.path.join(path, filename)
+					if os.path.isdir(full_name):
+						# For some reason mkdir and rmdir both fall into this 
+						# category
+						self.watch_directory(full_name)
+
+	def __call__(self):
+		return self.__dict__.pop('modified', False)