From 4ac0cdf084645e2aac15c2129bcbb1d414b4212c Mon Sep 17 00:00:00 2001
From: Michael Tremer <michael.tremer@ipfire.org>
Date: Sat, 4 Aug 2012 12:36:08 +0000
Subject: [PATCH] plugins: Restructure the plugin concept.

---
 collecty/plugins/base.py | 186 +++++++++++++++++++++++++++++----------
 1 file changed, 141 insertions(+), 45 deletions(-)

diff --git a/collecty/plugins/base.py b/collecty/plugins/base.py
index df2a7e5..183e4c5 100644
--- a/collecty/plugins/base.py
+++ b/collecty/plugins/base.py
@@ -19,76 +19,176 @@
 #                                                                             #
 ###############################################################################
 
+import logging
+import os
+import rrdtool
+import time
+
 from threading import Thread
 
+from ..constants import *
 from ..i18n import _
 
 class Plugin(Thread):
+	# The name of this plugin.
+	name = None
+
+	# A description for this plugin.
+	description = None
+
+	# The schema of the RRD database.
+	rrd_schema = None
+
+	# The default interval of this plugin.
+	default_interval = 60
+
 	def __init__(self, collecty, **kwargs):
 		Thread.__init__(self)
 		self.collecty = collecty
 
-		self.interval = int(kwargs.get("interval", 60))
+		# Check if this plugin was configured correctly.
+		assert self.name, "Name of the plugin is not set: %s" % self.name
+		assert self.description, "Description of the plugin is not set: %s" % self.description
+		assert self.rrd_schema
+
+		# Initialize the logger.
+		self.log = logging.getLogger("collecty.plugins.%s" % self.name)
+		self.log.propagate = 1
 
 		# Keepalive options
 		self.heartbeat = 2
-		self.killed = False
-
-		self.wakeup = self.interval / self.heartbeat
-
-		self.file = kwargs.get("file", None)
-		if not self.file.startswith("/"):
-			self.file = os.path.join("/var/rrd", self.file) 
+		self.running = True
 
 		self.data = []
 
+		# Create the database file.
 		self.create()
+
+		# Run some custom initialization.
+		self.init()
+
+		self.log.info(_("Successfully initialized."))
 	
 	def __repr__(self):
-		return "<Plugin %s>" % self._type
+		return "<Plugin %s>" % self.name
 	
 	def __str__(self):
-		return "Plugin %s %s" % (self._type, self.file)
-	
-	def run(self):
-		self.collecty.debug("%s started..." % self)
-		
-		c = 0
-		while True:
-			if self.killed:
-				self.update()
-				self.collecty.debug("%s stoppped..." % self)
-				return
+		return "Plugin %s %s" % (self.name, self.file)
+
+	@property
+	def interval(self):
+		"""
+			Returns the interval in milliseconds, when the read method
+			should be called again.
+		"""
+		# XXX read this from the settings
+
+		# Otherwise return the default.
+		return self.default_interval
+
+	@property
+	def file(self):
+		"""
+			The absolute path to the RRD file of this plugin.
+		"""
+		return os.path.join(DATABASE_DIR, "%s.rrd" % self.name)
 
-			if c == 0:
-				self.data.append(self.collect())
-				self.collecty.debug("%s collectd: %s..." % (self, self.data[-1]))
+	def create(self):
+		"""
+			Creates an empty RRD file with the desired data structures.
+		"""
+		# Skip if the file does already exist.
+		if os.path.exists(self.file):
+			return
 
-				self.update()
+		dirname = os.path.dirname(self.file)
+		if not os.path.exists(dirname):
+			os.makedirs(dirname)
 
-				c = self.wakeup
+		rrdtool.create(self.file, *self.rrd_schema)
 
-			c = c - 1
-			time.sleep(self.heartbeat)
+		self.log.debug(_("Created RRD file %s.") % self.file)
 
-	def shutdown(self):
-		self.killed = True
+	def info(self):
+		return rrdtool.info(self.file)
 
-	def time(self):
-		return int(time.time()) # Should return time as int in UTC
+	### Basic methods
+
+	def init(self):
+		"""
+			Do some custom initialization stuff here.
+		"""
+		pass
+
+	def read(self):
+		"""
+			Gathers the statistical data, this plugin collects.
+		"""
+		raise NotImplementedError
+
+	def submit(self):
+		"""
+			Flushes the read data to disk.
+		"""
+		# Do nothing in case there is no data to submit.
+		if not self.data:
+			return
+
+		self.collecty.debug(_("Saving data from %s...") % self)
+		rrdtool.update(self.file, *self.data)
+		self.data = []
 
-	def create(self):
-		if not os.path.exists(self.file):
-			rrdtool.create(self.file, *self._rrd)
+	def __read(self, *args, **kwargs):
+		"""
+			This method catches errors from the read() method and logs them.
+		"""
+		try:
+			return self.read(*args, **kwargs)
+
+		# Catch any exceptions, so collecty does not crash.
+		except Exception, e:
+			self.log.critical(_("Unhandled exception in read()!"), exc_info=True)
+
+	def __submit(self, *args, **kwargs):
+		"""
+			This method catches errors from the submit() method and logs them.
+		"""
+		try:
+			return self.submit(*args, **kwargs)
 
-	def update(self):
-		if self.data:
-			self.collecty.debug("%s saving data..." % self)
-			rrdtool.update(self.file, *self.data)
-			self.data = []
+		# Catch any exceptions, so collecty does not crash.
+		except Exception, e:
+			self.log.critical(_("Unhandled exception in submit()!"), exc_info=True)
+
+	def run(self):
+		self.log.debug(_("Started."))
 
-	def collect(self):
-		raise Exception, "Not implemented"
+		counter = 0
+		while self.running:
+			if counter == 0:
+				self.log.debug(_("Collecting..."))
+				self.__read()
+
+				self.log.debug(_("Sleeping for %.4fs.") % self.interval)
+
+				counter = self.interval / self.heartbeat
+
+			time.sleep(self.heartbeat)
+			counter -= 1
+
+		self.__submit()
+		self.log.debug(_("Stopped."))
+
+	def shutdown(self):
+		self.log.debug(_("Received shutdown signal."))
+		self.running = False
+
+	@property
+	def now(self):
+		"""
+			Returns the current timestamp in the UNIX timestamp format (UTC).
+		"""
+		return int(time.time())
 
 	def graph(self, file, interval=None):
 		args = [ "--imgformat", "PNG",
@@ -115,7 +215,3 @@ class Plugin(Thread):
 				args.append(item)
 
 			rrdtool.graph(file, *args)
-
-	def info(self):
-		return rrdtool.info(self.file)
-
-- 
2.39.2