From c61c0fc1d0aac94ccad531ad6841e3c99e02b90a Mon Sep 17 00:00:00 2001
From: Michal Cichra <michal@cichra.cz>
Date: Fri, 17 Mar 2017 12:46:57 +0100
Subject: [PATCH] [resolver] remove parallel dns query

lets delegate this work to a dns resolver like dnsmasq

it was broken and sometimes would return a string "killed" instead of
table with answers that would count as valid answer
---
 CHANGELOG.md                              |  1 +
 apicast/src/resty/resolver/dns_client.lua | 34 +----------------------
 2 files changed, 2 insertions(+), 33 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index cb50dcd80..f71860468 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -23,6 +23,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 ### Removed
 
 - Removed support for sending Request logs [PR #296](https://github.com/3scale/apicast/pull/296)
+- Support for parallel DNS query [PR #311](https://github.com/3scale/apicast/pull/311)
 
 ### Known Issues
 
diff --git a/apicast/src/resty/resolver/dns_client.lua b/apicast/src/resty/resolver/dns_client.lua
index dca7a964a..68e5fc81f 100644
--- a/apicast/src/resty/resolver/dns_client.lua
+++ b/apicast/src/resty/resolver/dns_client.lua
@@ -62,37 +62,6 @@ local function query(resolver, qname, opts, nameserver)
   return resolver:query(qname, opts)
 end
 
-local function parallel_query(resolvers, qname, opts)
-  local threads = {}
-  local n = #resolvers
-
-  if n < 1 then
-    return nil, 'no resolvers'
-  end
-
-  for i=1, n do
-    insert(threads, th_spawn(query, resolvers[i].resolver, qname, opts, resolvers[i].nameserver))
-  end
-
-  local answers, err
-
-  do
-    local found, ok
-    local i=1
-    repeat
-      ok, answers, err = th_wait(unpack(threads))
-      i = i + 1
-      found = ok and answers and not answers.errcode and not err
-    until found or i > n
-  end
-
-  for i=1, n do
-    th_kill(threads[i])
-  end
-
-  return answers, err
-end
-
 local function serial_query(resolvers, qname, opts)
   local answers, err
 
@@ -114,8 +83,7 @@ function _M.query(self, qname, opts)
     resolvers = self:init_resolvers()
   end
 
-  -- this is here so you can try the other one when suspicous something is wrong
-  return (parallel_query or serial_query)(resolvers, qname, opts)
+  return serial_query(resolvers, qname, opts)
 end
 
 return _M