Rename "Domain" to "VM" in various class names

The name "Domain", though technically correct from a Libvirt
perspective, was unnecessarily confusing. Call the class instances what
they are, VMs.

node-daemon/pvcd/VMConsoleWatcherInstance.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+
+# VMConsoleWatcherInstance.py - Class implementing a console log watcher for PVC domains
+# Part of the Parallel Virtual Cluster (PVC) system
+#
+#    Copyright (C) 2018  Joshua M. Boniface <joshua@boniface.me>
+#
+#    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 3 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, see <https://www.gnu.org/licenses/>.
+#
+###############################################################################
+
+import os
+import sys
+import uuid
+import time
+import threading
+import libvirt
+
+from collections import deque
+
+import fcntl
+import signal
+
+import pvcd.log as log
+import pvcd.zkhandler as zkhandler
+
+class VMConsoleWatcherInstance(object):
+    # Initialization function
+    def __init__(self, domuuid, domname, zk_conn, config, logger, this_node):
+        self.domuuid = domuuid
+        self.domname = domname
+        self.zk_conn = zk_conn
+        self.config = config
+        self.logfile = '{}/{}.log'.format(config['console_log_directory'], self.domname)
+        self.console_log_lines = config['console_log_lines']
+        self.logger = logger
+        self.this_node = this_node
+
+        # Try to append (create) the logfile and set its permissions
+        open(self.logfile, 'a').close()
+        os.chmod(self.logfile, 0o600)
+
+        self.logdeque = deque(open(self.logfile), self.console_log_lines)
+
+        self.stamp = None
+        self.cached_stamp = None
+
+        # Set up the deque with the current contents of the log
+        self.last_loglines = None
+        self.loglines = None
+
+        # Thread options
+        self.thread = None
+        self.thread_stopper = threading.Event()
+
+    # Start execution thread
+    def start(self):
+        self.thread_stopper.clear()
+        self.thread = threading.Thread(target=self.run, args=(), kwargs={})
+        self.logger.out('Starting VM log parser', state='i', prefix='Domain {}:'.format(self.domuuid))
+        self.thread.start()
+
+    # Stop execution thread
+    def stop(self):
+        if self.thread and self.thread.isAlive():
+            self.logger.out('Stopping VM log parser', state='i', prefix='Domain {}:'.format(self.domuuid))
+            self.thread_stopper.set()
+            # Do one final flush
+            self.update()
+
+    # Main entrypoint
+    def run(self):
+        # Main loop
+        while not self.thread_stopper.is_set():
+            self.update()
+            time.sleep(0.5)
+
+    def update(self):
+        self.stamp = os.stat(self.logfile).st_mtime
+        if self.stamp != self.cached_stamp:
+            self.cached_stamp = self.stamp
+            self.fetch_lines()
+        # Update Zookeeper with the new loglines if they changed
+        if self.loglines != self.last_loglines:
+            zkhandler.writedata(self.zk_conn, { '/domains/{}/consolelog'.format(self.domuuid): self.loglines })
+            self.last_loglines = self.loglines
+
+    def fetch_lines(self):
+        self.logdeque = deque(open(self.logfile), self.console_log_lines)
+        self.loglines = ''.join(self.logdeque)