cola/inotify.py

   1 # Copyright (c) 2008 David Aguilar
   2 """Provides an inotify plugin for Linux and other systems with pyinotify"""
   3
   4 import os
   5 import time
   6
   7 try:
   8     import pyinotify
   9     from pyinotify import ProcessEvent
  10     from pyinotify import WatchManager
  11     from pyinotify import Notifier
  12     from pyinotify import EventsCodes
  13     AVAILABLE = True
  14 except ImportError:
  15     ProcessEvent = object
  16     AVAILABLE = False
  17     pass
  18
  19 from PyQt4 import QtCore
  20
  21 import cola
  22 from cola import signals
  23 from cola import utils
  24 from cola.compat import set
  25
  26 INOTIFY_EVENT = QtCore.QEvent.User + 0
  27
  28
  29 _thread = None
  30 def start():
  31     global _thread
  32     if not AVAILABLE:
  33         if not utils.is_linux():
  34             return
  35         msg = ('inotify: disabled\n'
  36                'Note: install python-pyinotify to enable inotify.\n')
  37
  38         if utils.is_debian():
  39             msg += ('On Debian systems '
  40                     'try: sudo aptitude install python-pyinotify')
  41         cola.notifier().broadcast(signals.log_cmd, 0, msg)
  42         return
  43
  44     # Start the notification thread
  45     _thread = GitNotifier()
  46     _thread.start()
  47     msg = 'inotify support: enabled'
  48     cola.notifier().broadcast(signals.log_cmd, 0, msg)
  49     cola.notifier().broadcast(signals.inotify, True)
  50
  51
  52 def stop():
  53     if not has_inotify():
  54         return
  55     _thread.set_abort(True)
  56     _thread.quit()
  57     _thread.wait()
  58
  59
  60 def has_inotify():
  61     """Return True if pyinotify is available."""
  62     return AVAILABLE and _thread and _thread.isRunning()
  63
  64
  65 class EventReceiver(QtCore.QObject):
  66     def event(self, msg):
  67         """Overrides event() to handle custom inotify events."""
  68         if not AVAILABLE:
  69             return
  70         if msg.type() == INOTIFY_EVENT:
  71             cola.notifier().broadcast(signals.rescan)
  72             return True
  73         else:
  74             return False
  75
  76
  77 class FileSysEvent(ProcessEvent):
  78     """Generated by GitNotifier in response to inotify events"""
  79
  80     def __init__(self, parent):
  81         """Keep a reference to the QThread parent and maintain event state"""
  82         ProcessEvent.__init__(self)
  83         ## The Qt parent
  84         self._parent = parent
  85         ## Timer used to prevents notification floods
  86         self._last_event_time = time.time()
  87
  88     def process_default(self, event):
  89         """Notifies the Qt parent when actions occur"""
  90         ## Limit the notification frequency to 1 per second
  91         if time.time() - self._last_event_time > 1.0:
  92             self._parent.notify()
  93         self._last_event_time = time.time()
  94
  95
  96 class GitNotifier(QtCore.QThread):
  97     """Polls inotify for changes and generates FileSysEvents"""
  98
  99     def __init__(self, timeout=250):
 100         """Set up the pyinotify thread"""
 101         QtCore.QThread.__init__(self)
 102         self.setTerminationEnabled(True)
 103
 104         ## QApplication receiver of Qt events
 105         self._receiver = EventReceiver()
 106         ## Git command object
 107         self._git = cola.model().git
 108         ## pyinotify timeout
 109         self._timeout = timeout
 110         ## Path to monitor
 111         self._path = self._git.worktree()
 112         ## Signals thread termination
 113         self._abort = False
 114         ## Directories to watching
 115         self._dirs_seen = set()
 116         ## The inotify watch manager instantiated in run()
 117         self._wmgr = None
 118         ## Events to capture
 119         self._mask = (EventsCodes.ALL_FLAGS['IN_CREATE'] |
 120                       EventsCodes.ALL_FLAGS['IN_DELETE'] |
 121                       EventsCodes.ALL_FLAGS['IN_MODIFY'] |
 122                       EventsCodes.ALL_FLAGS['IN_MOVED_TO'])
 123
 124     def set_abort(self, abort):
 125         """Tells the GitNotifier to abort"""
 126         self._abort = abort
 127
 128     def notify(self):
 129         """Post a Qt event in response to inotify updates"""
 130         if not self._abort:
 131             event_type = QtCore.QEvent.Type(INOTIFY_EVENT)
 132             event = QtCore.QEvent(event_type)
 133             QtCore.QCoreApplication.postEvent(self._receiver, event)
 134
 135     def _watch_directory(self, directory):
 136         """Set up a directory for monitoring by inotify"""
 137         if not self._wmgr:
 138             return
 139         directory = os.path.realpath(directory)
 140         if not os.path.exists(directory):
 141             return
 142         if directory not in self._dirs_seen:
 143             self._wmgr.add_watch(directory, self._mask)
 144             self._dirs_seen.add(directory)
 145
 146     def _is_pyinotify_08x(self):
 147         """Is this pyinotify 0.8.x?
 148
 149         The pyinotify API changed between 0.7.x and 0.8.x.
 150         This allows us to maintain backwards compatibility.
 151         """
 152         if hasattr(pyinotify, '__version__'):
 153             if pyinotify.__version__[:3] == '0.8':
 154                 return True
 155         return False
 156
 157     def run(self):
 158         """Create the inotify WatchManager and generate FileSysEvents"""
 159         # Only capture events that git cares about
 160         self._wmgr = WatchManager()
 161         if self._is_pyinotify_08x():
 162             notifier = Notifier(self._wmgr, FileSysEvent(self),
 163                                 timeout=self._timeout)
 164         else:
 165             notifier = Notifier(self._wmgr, FileSysEvent(self))
 166         dirs_seen = set()
 167         added_flag = False
 168         # self._abort signals app termination.  The timeout is a tradeoff
 169         # between fast notification response and waiting too long to exit.
 170         while not self._abort:
 171             if not added_flag:
 172                 self._watch_directory(self._path)
 173                 # Register files/directories known to git
 174                 for filename in self._git.ls_files().splitlines():
 175                     directory = os.path.dirname(filename)
 176                     self._watch_directory(directory)
 177                 added_flag = True
 178             notifier.process_events()
 179             if self._is_pyinotify_08x():
 180                 check = notifier.check_events()
 181             else:
 182                 check = notifier.check_events(timeout=self._timeout)
 183             if check:
 184                 notifier.read_events()
 185         notifier.stop()