fixed DNS query module, where uncaching entries was just trying to perform a different query after some time, until all record types (A and AAAA) were drained; this also clears the logic on when a tcp connection can't be established cuz EHOSTUNREACH

lib/httpx/connection.rb

@@ -61,7 +61,7 @@ module HTTPX
       channel.on(:reset) do
         @timeout.transition(:idle)
       end
-      channel.once(:unreachable) do
+      channel.on(:unreachable) do
         @resolver.uncache(channel)
         resolve_channel(channel)
       end

lib/httpx/resolver/https.rb

@@ -67,7 +67,7 @@ module HTTPX
     def resolve(channel = @channels.first, hostname = nil)
       return if @building_channel
       hostname = hostname || @queries.key(channel) || channel.uri.host
-      type = @_record_types[hostname].shift
+      type = @_record_types[hostname].first
       log(label: "resolver: ") { "query #{type} for #{hostname}" }
       begin
         request = build_request(hostname, type)
@@ -122,7 +122,9 @@ module HTTPX
       end
       if answers.empty?
         host, channel = @queries.first
+        @_record_types[host].shift
         if @_record_types[host].empty?
+          @_record_types.delete(host)
           emit_resolve_error(channel, host)
           return
         end

lib/httpx/resolver/native.rb

@@ -190,7 +190,9 @@ module HTTPX
 
       if addresses.empty?
         hostname, channel = @queries.first
+        @_record_types[hostname].shift
         if @_record_types[hostname].empty?
+          @_record_types.delete(hostname)
           emit_resolve_error(channel, hostname)
           return
         end
@@ -221,7 +223,7 @@ module HTTPX
       return unless @write_buffer.empty?
       hostname = hostname || @queries.key(channel) || channel.uri.host
       @queries[hostname] = channel
-      type = @_record_types[hostname].shift
+      type = @_record_types[hostname].first
       log(label: "resolver: ") { "query #{type} for #{hostname}" }
       begin
         @write_buffer << Resolver.encode_dns_query(hostname, type: RECORD_TYPES[type])

lib/httpx/resolver/resolver_mixin.rb

@@ -21,6 +21,7 @@ module HTTPX
       def uncache(channel)
         hostname = hostname || @queries.key(channel) || channel.uri.host
         Resolver.uncache(hostname)
+        @_record_types[hostname].shift
       end
 
       private