minor lints and cleanup to sharding

Author: naterush

casper/protocols/sharding/forkchoice.py

@@ -7,7 +7,7 @@ def get_max_weight_indexes(scores):
 
     max_score = max(scores.values())
 
-    assert max_score != 0, "max_score of a block should never be zero"
+    assert max_score > 0, "max_score should be greater than zero"
 
     max_weight_estimates = {e for e in scores if scores[e] == max_score}
 

casper/protocols/sharding/sharding_view.py

@@ -65,11 +65,11 @@ def set_child_starting_block(self, tip_block, parent_id, child_id):
 
     def select_random_shards(self, shards_forkchoice):
         """Randomly selects a shard to build on, and sometimes selects another child shard"""
-        shards_to_build_on = [r.choice([key for key in self.starting_blocks.keys()])]
-        if (r.randint(0, 1) == 1):
-            child = str(r.randint(0, 1))
-            if shards_to_build_on[0] + child in self.starting_blocks:
-                shards_to_build_on.append(shards_to_build_on[0] + child)
+        shards_to_build_on = [r.choice(list(self.starting_blocks.keys()))]
+        if r.choice([True, False]):
+            child_shard_id = shards_to_build_on[0] + str(r.randint(0, 1))
+            if child_shard_id in self.starting_blocks:
+                shards_to_build_on.append(child_shard_id)
 
         return set(shards_to_build_on)
 
@@ -113,18 +113,6 @@ def update_safe_estimates(self, validator_set):
         # check the safety of the top shard!
         pass
 
-        tip = None
-
-        while tip and tip != self.starting_blocks['']:
-            oracle = CliqueOracle(tip, self, validator_set)
-            fault_tolerance, _ = oracle.check_estimate_safety()
-
-            if fault_tolerance > 0:
-                self.starting_blocks[''] = tip
-                return tip
-
-            tip = tip.prev_block('')
-
     def _update_protocol_specific_view(self, message):
         """Given a now justified message, updates children and when_recieved"""
         assert message.hash in self.justified_messages, "...should not have seen message!"