State and check assumptions in Power.from_list()

monitoring/db/scripts/get_detailed_power.py

@@ -39,7 +39,14 @@ class Power:
 
 	@classmethod
 	def from_list(cls, data):
-		"""Assumes data is a list of tuples (timestamp, node, value)"""
+		"""
+		Returns a Power instance from a list of tuples (timestamp, node, value).
+
+		Assumptions:
+		 - data is sorted by timestamp first, then by node. Both ascending.
+		 - for each timestamp, there is the same set of nodes.
+		"""
+
 		idx_ts = 0; idx_node = 1; idx_value = 2
 		nodes = list(set([line[idx_node] for line in data]))
 		cls = Power(nodes)
@@ -54,9 +61,23 @@ class Power:
 			power = l[idx_value]
 			values[ts].append(power)
 
-		epochs = sorted(values.keys())
+		epochs = values.keys()
 		for epoch in epochs:
 			cls.insert_epoch(epoch, values[epoch])
+
+		# check implicit assumptions: 1) ts/epochs are sorted
+		e = list(epochs)
+		k = list(values.keys())
+		if not e == k:
+			print("Warning: Unexpected unsorted timestamps.")
+
+		# check implicit assumptions: 2) each line has #nodes values
+		nnodes = len(nodes)
+		for epoch in epochs:
+			actual = len(values[epoch])
+			if actual != nnodes:
+				print("Warning: Unexpected number of nodes ({actual}/{expected})".format(actual=actual, expected=nnodes))
+				break
 		
 		return cls