From ea6b2b98fb3d93f0bbee2001a5c358b1f84839d4 Mon Sep 17 00:00:00 2001
From: Victor Shyba <victor1984@riseup.net>
Date: Sat, 29 Sep 2018 23:53:40 -0300
Subject: [PATCH] refactor ping queue

---
 lbrynet/dht/node.py                          |  4 +-
 lbrynet/dht/protocol.py                      | 67 +++++++-------------
 tests/functional/dht/dht_test_environment.py |  4 +-
 3 files changed, 26 insertions(+), 49 deletions(-)

diff --git a/lbrynet/dht/node.py b/lbrynet/dht/node.py
index 096e46b91..a085ed1b2 100644
--- a/lbrynet/dht/node.py
+++ b/lbrynet/dht/node.py
@@ -644,10 +644,10 @@ class Node(MockKademliaHelper):
         defer.returnValue(None)
 
     def _refreshContacts(self):
-        self._protocol._ping_queue.enqueue_maybe_ping(*self.contacts, delay=0)
+        self._protocol._ping_queue.enqueue_maybe_ping(*self.contacts)
 
     def _refreshStoringPeers(self):
-        self._protocol._ping_queue.enqueue_maybe_ping(*self._dataStore.getStoringContacts(), delay=0)
+        self._protocol._ping_queue.enqueue_maybe_ping(*self._dataStore.getStoringContacts())
 
     @defer.inlineCallbacks
     def _refreshRoutingTable(self):
diff --git a/lbrynet/dht/protocol.py b/lbrynet/dht/protocol.py
index 3538269b6..0bfdbf953 100644
--- a/lbrynet/dht/protocol.py
+++ b/lbrynet/dht/protocol.py
@@ -1,7 +1,6 @@
 import logging
 import errno
 from binascii import hexlify
-from collections import deque
 
 from twisted.internet import protocol, defer
 from .error import BUILTIN_EXCEPTIONS, UnknownRemoteException, TimeoutError, TransportNotConnected
@@ -22,58 +21,36 @@ class PingQueue:
 
     def __init__(self, node):
         self._node = node
-        self._get_time = self._node.clock.seconds
-        self._queue = deque()
         self._enqueued_contacts = {}
         self._process_lc = node.get_looping_call(self._process)
 
     def enqueue_maybe_ping(self, *contacts, **kwargs):
-        schedule = self._get_time() + (kwargs.get('delay', constants.checkRefreshInterval))
+        no_op = (defer.succeed(None), lambda: None)
         for contact in contacts:
-            if contact not in self._enqueued_contacts:
-                self._enqueued_contacts[contact] = schedule
-                self._queue.append(contact)
+            self._enqueued_contacts.setdefault(contact, no_op)
+
+    @defer.inlineCallbacks
+    def _ping(self, contact):
+        if contact.contact_is_good:
+            return
+        try:
+            yield contact.ping()
+        except TimeoutError:
+            pass
+        except Exception as err:
+            log.warning("unexpected error: %s", err)
+        finally:
+            if contact in self._enqueued_contacts:
+                del self._enqueued_contacts[contact]
 
     def _process(self):
-        if not len(self._queue):
+        if not self._enqueued_contacts:
             return
-        contact = self._queue.popleft()
-        now = self._get_time()
-
-        # if the oldest contact in the queue isn't old enough to be pinged, add it back to the queue and return
-        if now < self._enqueued_contacts[contact]:
-            self._queue.appendleft(contact)
-            return
-
-        pinged = []
-        checked = []
-        while now > self._enqueued_contacts[contact]:
-            checked.append(contact)
-            if not contact.contact_is_good:
-                pinged.append(contact)
-            if not len(self._queue):
-                break
-            contact = self._queue.popleft()
-            if not now > self._enqueued_contacts[contact]:
-                checked.append(contact)
-
-        @defer.inlineCallbacks
-        def _ping(contact):
-            try:
-                yield contact.ping()
-            except TimeoutError:
-                pass
-            except Exception as err:
-                log.warning("unexpected error: %s", err)
-
-        d = defer.DeferredList([_ping(contact) for contact in pinged])
-
-        for contact in checked:
-            if contact in self._enqueued_contacts and contact in pinged:
-                del self._enqueued_contacts[contact]
-            elif contact not in self._queue:
-                self._queue.appendleft(contact)
-        return d
+        # spread pings across 60 seconds to avoid flood and/or false negatives
+        step = 60.0/float(len(self._enqueued_contacts))
+        for index, (contact, (call, _)) in enumerate(self._enqueued_contacts.items()):
+            if call.called and not contact.contact_is_good:
+                self._enqueued_contacts[contact] = self._node.reactor_callLater(index*step, self._ping, contact)
 
     def start(self):
         return self._node.safe_start_looping_call(self._process_lc, 60)
diff --git a/tests/functional/dht/dht_test_environment.py b/tests/functional/dht/dht_test_environment.py
index 8c431c5ec..7dd138dc0 100644
--- a/tests/functional/dht/dht_test_environment.py
+++ b/tests/functional/dht/dht_test_environment.py
@@ -47,8 +47,8 @@ class TestKademliaBase(unittest.TestCase):
         :param step: reactor tick rate (in seconds)
         """
         advanced = 0.0
+        self.clock._sortCalls()
         while advanced < n:
-            self.clock._sortCalls()
             if step:
                 next_step = step
             elif self.clock.getDelayedCalls():
@@ -120,7 +120,7 @@ class TestKademliaBase(unittest.TestCase):
         seed_dl = []
         seeds = sorted(list(self.seed_dns.keys()))
         known_addresses = [(seed_name, 4444) for seed_name in seeds]
-        for seed_dns in seeds:
+        for _ in range(len(seeds)):
             self._add_next_node()
             seed = self.nodes.pop()
             self._seeds.append(seed)