vote_q proc pickle -> JSON msg migration part 1

Part 1 of a multi-phase commit to migrate the message format
of the vote queues from pickle to JSON.

This first part updates the processor to be able to read from
both the pickle and the JSON formats.

r2/r2/lib/db/queries.py

@@ -19,6 +19,7 @@
 # All portions of the code written by reddit are Copyright (c) 2006-2015 reddit
 # Inc. All Rights Reserved.
 ###############################################################################
+import json
 
 from r2.models import Account, Link, Comment, Report, LinksByAccount
 from r2.models.vote import cast_vote, get_votes, VotesByAccount
@@ -1852,12 +1853,26 @@ def _handle_vote(msg):
         timer = stats.get_timer("service_time." + stats_qname)
         timer.start()
 
-        #assert(len(msgs) == 1)
-        r = pickle.loads(msg.body)
-
-        uid, tid, dir, ip, vote_info, cheater = r
-        voter = Account._byID(uid, data=True)
-        votee = Thing._by_fullname(tid, data = True)
+        # Temporary shim: During queue message format transition,
+        # JSON payloads will be explicitly marked as such.
+        msg_headers = msg.properties.get("application_headers", {})
+        if msg_headers.get("format", "pickle") == "json":
+            vote = json.loads(msg.body)
+        else:
+            uid, tid, dir, ip, info, cheater = pickle.loads(msg.body)
+            vote = {
+                "uid": uid,
+                "tid": tid,
+                "dir": dir,
+                "ip": ip,
+                "info": info,
+                "cheater": cheater,
+                "event": None,
+            }
+            del uid, tid, dir, ip, info, cheater
+
+        voter = Account._byID(vote["uid"], data=True)
+        votee = Thing._by_fullname(vote["tid"], data=True)
         timer.intermediate("preamble")
 
         # Convert the naive timestamp we got from amqplib to a
@@ -1868,17 +1883,18 @@ def _handle_vote(msg):
         # I don't know how, but somebody is sneaking in votes
         # for subreddits
         if isinstance(votee, (Link, Comment)):
-            print (voter, votee, dir, ip, vote_info, cheater)
-            handle_vote(voter, votee, dir, ip, vote_info,
-                        cheater = cheater, foreground=True, timer=timer,
+            print (voter, votee, vote["dir"], vote["ip"], vote["info"],
+                   vote["cheater"])
+            handle_vote(voter, votee, vote["dir"], vote["ip"], vote["info"],
+                        cheater=vote["cheater"], foreground=True, timer=timer,
                         date=date)
 
         if isinstance(votee, Comment):
             update_comment_votes([votee])
             timer.intermediate("update_comment_votes")
 
         stats.simple_event('vote.total')
-        if cheater:
+        if vote["cheater"]:
             stats.simple_event('vote.cheater')
         timer.flush()