--- /dev/null
+#
+#
+
+# Copyright (C) 2006, 2007, 2008 Google Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+# General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301, USA.
+
+
+"""Module with helper classes and functions for daemons"""
+
+
+import select
+import signal
+import errno
+
+from ganeti import utils
+
+
+class Mainloop(object):
+ """Generic mainloop for daemons
+
+ """
+ def __init__(self):
+ self._io_wait = []
+ self._signal_wait = []
+ self.sigchld_handler = {}
+
+ def Run(self):
+ # TODO: Does not yet support adding new event sources while running
+ poller = select.poll()
+ for (owner, fd, conditions) in self._io_wait:
+ poller.register(fd, conditions)
+
+ self.sigchld_handler = utils.SignalHandler([signal.SIGCHLD])
+ try:
+ while True:
+ try:
+ io_events = poller.poll(1000)
+ except select.error, err:
+ # EINTR can happen when signals are sent
+ if err.args and err.args[0] in (errno.EINTR,):
+ io_events = None
+ else:
+ raise
+
+ if io_events:
+ # Check for I/O events
+ for (evfd, evcond) in io_events:
+ for (owner, fd, conditions) in self._io_wait:
+ if fd == evfd and evcond & conditions:
+ owner.OnIO(fd, evcond)
+
+ # Check whether signal was raised
+ if self.sigchld_handler.called:
+ for owner in self._signal_wait:
+ owner.OnSignal(signal.SIGCHLD)
+ self.sigchld_handler.Clear()
+ finally:
+ self.sigchld_handler.Reset()
+ self.sigchld_handler = None
+
+ def RegisterIO(self, owner, fd, condition):
+ """Registers a receiver for I/O notifications
+
+ The receiver must support a "OnIO(self, fd, conditions)" function.
+
+ @type owner: instance
+ @param owner: Receiver
+ @type fd: int
+ @param fd: File descriptor
+ @type condition: int
+ @param condition: ORed field of conditions to be notified
+ (see select module)
+
+ """
+ self._io_wait.append((owner, fd, condition))
+
+ def RegisterSignal(self, owner):
+ """Registers a receiver for signal notifications
+
+ The receiver must support a "OnSignal(self, signum)" function.
+
+ @type owner: instance
+ @param owner: Receiver
+
+ """
+ self._signal_wait.append(owner)