Periodically ping server to detect disconnection

In some cases, disconnection from the server can be unclean and won't be
noticed until the bot tries to send a message, which may never happen if
it did not disconnect during the game. To solve this problem, it will
now ping the server every 2 minutes by default, which will result in
a broken pipe error if the connection is dead. This won't be able to
detect netsplits where the server the bot is on stays online, because
those are impossible to correctly detect in every case.

This commit also adds a !latency command so that users can verify if the
bot is lagging.

messages/en.json

@@ -33,6 +33,7 @@
         "Give me a ping, Vasily. One ping only, please.",
         "Would you people please leave me alone? Seriously."
     ],
+    "latency": "{0:.3f} second{1}.",
     "lynch_reveal": [
         "The villagers, after much debate, finally decide on lynching \u0002{0}\u0002, who turned out to be... a{1} \u0002{2}\u0002.",
         "After a prolonged struggle, \u0002{0}\u0002 is forced to the gallows, and is discovered after death to be a{1} \u0002{2}\u0002.",

src/handler.py

@@ -3,6 +3,8 @@
 import base64
 import socket
 import sys
+import threading
+import time
 import traceback
 
 import botconfig
@@ -44,6 +46,13 @@ def unhandled(cli, prefix, cmd, *args):
     for fn in decorators.HOOKS.get(cmd, []):
         fn.caller(cli, prefix, *args)
 
+def ping_server(cli):
+    if var.SERVER_PING_INTERVAL > 0:
+        ts = time.time()
+        var.LAST_SERVER_PING = ts
+        cli.send("PING :{0}".format(ts))
+        threading.Timer(var.SERVER_PING_INTERVAL, ping_server, args=(cli,)).start()
+
 def connect_callback(cli):
     regaincount = 0
     releasecount = 0
@@ -81,6 +90,8 @@ def connect_callback(cli):
 
         users.Bot.change_nick(botconfig.NICK)
 
+        ping_server(cli)
+
     def mustregain(cli, server, bot_nick, nick, msg):
         nonlocal regaincount
 

src/settings.py

@@ -204,6 +204,9 @@ DEV_CHANNEL = ""
 DEV_PREFIX = ""
 PASTEBIN_ERRORS = False
 
+# How often to ping the server (in seconds) to detect unclean disconnection
+SERVER_PING_INTERVAL = 120
+LAST_SERVER_PING = None
 
 # TODO: move this to a game mode called "fixed" once we implement a way to randomize roles (and have that game mode be called "random")
 DEFAULT_ROLE = "villager"

src/wolfgame.py

@@ -46,7 +46,7 @@ import botconfig
 import src
 import src.settings as var
 from src.utilities import *
-from src import db, events, channels, users, hooks, logger, proxy, debuglog, errlog, plog
+from src import db, events, channels, users, handler, hooks, logger, proxy, debuglog, errlog, plog
 from src.decorators import command, cmd, hook, handle_error, event_listener, COMMANDS
 from src.messages import messages
 from src.warnings import *
@@ -481,7 +481,6 @@ def restart_program(cli, nick, chan, rest): # XXX: sighandler (top of file) also
     # handler now, but I'm keeping it for now just in case.
     var.RESTARTING = True
 
-
 @cmd("ping", pm=True)
 def pinger(cli, nick, chan, rest):
     """Check if you or the bot is still connected."""
@@ -491,6 +490,16 @@ def pinger(cli, nick, chan, rest):
         cmd_char=botconfig.CMD_CHAR,
         goat_action=random.choice(messages["goat_actions"])))
 
+@cmd("latency", pm=True)
+def latency(cli, nick, chan, rest):
+    handler.ping_server(cli)
+
+    @hook("pong", hookid=300)
+    def latency_pong(cli, server, target, ts):
+        lat = round(time.time() - var.LAST_SERVER_PING, 3)
+        reply(cli, nick, chan, messages["latency"].format(lat, "" if lat == 1 else "s"))
+        hook.unhook(300)
+
 @cmd("simple", raw_nick=True, pm=True)
 def mark_simple_notify(cli, nick, chan, rest):
     """Makes the bot give you simple role instructions, in case you are familiar with the roles."""