From e4364b75b153981db0ea5aa41f681795e791935c Mon Sep 17 00:00:00 2001
From: Christopher Usher <chrusher@gmail.com>
Date: Tue, 7 May 2019 13:16:10 +0100
Subject: [PATCH] options to change where the node list is coming from

---
 backfiller/backfiller/main.py | 36 ++++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 13 deletions(-)

diff --git a/backfiller/backfiller/main.py b/backfiller/backfiller/main.py
index 837c3df..e42251d 100644
--- a/backfiller/backfiller/main.py
+++ b/backfiller/backfiller/main.py
@@ -1,5 +1,5 @@
 """Download segments from other nodes to catch stuff this node missed."""
-# TODO more logging, better exception handling
+# TODO more logging
 
 import datetime
 import errno
@@ -36,19 +36,27 @@ def encode_strings(o):
 		return o.encode('utf-8')
 	return o
 
-def get_nodes():
+def get_nodes(node_source=None):
 	"""List address of other wubloaders.
 	
 	This returns a list of the other wubloaders as strings of the form
 	'protocol://host:port/'"""
-	# either read a config file or query the database to get the addresses
-	# of the other nodes
-	# figure out some way that the local machine isn't in the list of returned
-	# nodes 
 
-	logging.info('Fetching list of other nodes')
 
-	nodes = []
+	if node_source == 'file':
+		logging.info('Fetching list of other nodes from file')
+		# read a config file
+		# should I allow any filename?
+		pass
+
+	elif node_source == 'database':
+		logging.info('Fetching list of other nodes from database')
+		# query the database
+		pass
+
+	else:
+		nodes = []
+	
 	return nodes
 
 
@@ -163,7 +171,7 @@ class BackfillerManager(object):
 
 	NODE_INTERVAL = 300 #seconds between updating list of nodes
 
-	def __init__(self, base_dir, stream, variants, static_nodes=[], start=None, run_once=False):
+	def __init__(self, base_dir, stream, variants, static_nodes=[], start=None, run_once=False, node_source=None):
 		"""Constructor for BackfillerManager.
 		Creates a manager for a given stream with specified variants. If
 		static_nodes is None, manager"""
@@ -173,6 +181,7 @@ class BackfillerManager(object):
 		self.static_nodes = static_nodes
 		self.start = start
 		self.run_once = run_once
+		self.node_source
 		self.stopping = gevent.event.Event()
 		self.logger = logging.getLogger("BackfillerManager({})".format(stream))
 		self.workers = {} # {node url: worker}
@@ -186,7 +195,7 @@ class BackfillerManager(object):
 
 	def start_worker(self, node):
 		"""Start a new worker for given node."""
-		worker = BackfillerWorker(self, self.base_dir, node)
+		worker = BackfillerWorker(self, node)
 		assert node not in self.workers, "Tried to start worker for node {!r} that already has one".format(node)
 		self.workers[node] = worker
 		gevent.spawn(worker.run)
@@ -198,7 +207,7 @@ class BackfillerManager(object):
 	def run(self):
 		self.logger.info('Starting')
 		while not self.stopping.is_set():
-			new_nodes = set(get_nodes() + self.static_nodes)
+			new_nodes = set(get_nodes(self.node_source) + self.static_nodes)
 			exisiting_nodes = set(self.workers.keys())
 			to_start = new_nodes - exisiting_nodes
 			for node in to_start:
@@ -322,7 +331,8 @@ class BackfillerWorker(object):
 
 							
 def main(base_dir='.', stream='', variants='', metrics_port=8002,
-	static_nodes='', backdoor_port=0, start=None, run_once=False):
+	static_nodes='', backdoor_port=0, start=None, run_once=False,
+	node_source=None):
 	"""Backfiller service."""
 
 	variants = variants.split(',') if variants else []
@@ -334,7 +344,7 @@ def main(base_dir='.', stream='', variants='', metrics_port=8002,
 		except ValueError:
 			start = dateutil.parser.parse(start)
 
-	manager = BackfillerManager(base_dir, stream, variants, static_nodes, start, run_once)
+	manager = BackfillerManager(base_dir, stream, variants, static_nodes, start, run_once, node_source)
 	gevent.signal(signal.SIGTERM, manager.stop)
 
 	common.PromLogCountsHandler.install()