Read from DNS cache if within TTL #677

erikjohnston · Mar 31, 2016

No description provided.

Hmm, I tend to prefer to pass in the current time to these things to make testing easier.

As above wrt to passing in the current time, or using a mockable clock for getting the current time.

Now that resolve_service takes a clock, it might be worth using a mock clock here?
Also might be nice to have a test that checks that things expire.

erikjohnston · Apr 6, 2016

NegativeMjark · Apr 8, 2016

LGTM

erikjohnston assigned NegativeMjark Mar 31, 2016

oddvar added the in progress label Mar 31, 2016

richvdh deleted the erikj/dns_cache branch Dec 1, 2016

@@ -154,6 +156,12 @@ def connect(self, protocolFactory):
      @defer.inlineCallbacks
      def resolve_service(service_name, dns_client=client, cache=SERVER_CACHE):
+    +    cache_entry = cache.get(service_name, None)
+    +    if cache_entry:
+    +        if all(s.expires > int(time.time()) for s in cache_entry):

-    -                    host=ip,
-    -                    port=int(payload.port),
-    -                    priority=int(payload.priority),
-    -                    weight=int(payload.weight)
-    -                ))
+    +            for answer in answers:
+    +                if answer.type == dns.A and answer.payload:
+    +                    ip = answer.payload.dottedQuad()
+    +                    host_ttl = min(srv_ttl, answer.ttl)
+    +
+    +                    servers.append(_Server(
+    +                        host=ip,
+    +                        port=int(payload.port),
+    +                        priority=int(payload.priority),
+    +                        weight=int(payload.weight),
+    +                        expires=int(time.time()) + host_ttl,

              cache = {
-    -            service_name: [object()]
+    +            service_name: [entry]
              }
              servers = yield resolve_service(

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