https resolver: close the http-2 connection on error

the connection was being kept open beyond the scope of the session
scope.

also, the connection wasn't deactivated after use, lingering in the
selector.

lib/httpx/resolver/https.rb

@@ -31,7 +31,7 @@ module HTTPX
     }.freeze
 
     def_delegators :@resolver_connection, :state, :connecting?, :to_io, :call, :close,
-                   :terminate, :inflight?, :handle_socket_timeout
+                   :closed?, :deactivate, :terminate, :inflight?, :handle_socket_timeout
 
     def initialize(_, options)
       super
@@ -109,6 +109,7 @@ module HTTPX
         reset_hostname(hostname)
         throw(:resolve_error, e) if connection.pending.empty?
         emit_resolve_error(connection, connection.peer.host, e)
+        close_or_resolve
       end
     end
 
@@ -118,6 +119,7 @@ module HTTPX
       hostname = @requests.delete(request)
       connection = reset_hostname(hostname)
       emit_resolve_error(connection, connection.peer.host, e)
+      close_or_resolve
     else
       # @type var response: HTTPX::Response
       parse(request, response)
@@ -144,6 +146,7 @@ module HTTPX
 
         unless @queries.value?(connection)
           emit_resolve_error(connection)
+          close_or_resolve
           return
         end
 
@@ -153,10 +156,12 @@ module HTTPX
         connection = reset_hostname(host)
 
         emit_resolve_error(connection)
+        close_or_resolve
       when :decode_error
         host = @requests.delete(request)
         connection = reset_hostname(host)
         emit_resolve_error(connection, connection.peer.host, result)
+        close_or_resolve
       end
     end
 
@@ -166,6 +171,7 @@ module HTTPX
         host = @requests.delete(request)
         connection = reset_hostname(host)
         emit_resolve_error(connection)
+        close_or_resolve
         return
 
       else
@@ -204,9 +210,7 @@ module HTTPX
           catch(:coalesced) { emit_addresses(connection, @family, addresses.map { |a| Resolver::Entry.new(a["data"], a["TTL"]) }) }
         end
       end
-      return if @connections.empty?
-
-      resolve
+      close_or_resolve(true)
     end
 
     def build_request(hostname)
@@ -249,5 +253,20 @@ module HTTPX
 
       connection
     end
+
+    def close_or_resolve(should_deactivate = false)
+      # drop already closed connections
+      @connections.shift until @connections.empty? || @connections.first.state != :closed
+
+      if (@connections - @queries.values).empty?
+        if should_deactivate
+          deactivate
+        else
+          disconnect
+        end
+      else
+        resolve
+      end
+    end
   end
 end

sig/resolver/https.rbs

@@ -40,6 +40,8 @@ module HTTPX
       def decode_response_body: (Response) -> dns_decoding_response
 
       def reset_hostname: (String hostname, ?reset_candidates: bool) -> Connection?
+
+      def close_or_resolve: (?bool should_deactivate) -> void
     end
   end
 end

sig/resolver/resolver.rbs

@@ -58,6 +58,8 @@ module HTTPX
       def emit_resolve_error: (Connection connection, ?String hostname, ?StandardError) -> void
 
       def resolve_error: (String hostname, ?StandardError?) -> (ResolveError | ResolveTimeoutError)
+
+      def close_or_resolve: () -> void
     end
   end
 end

test/support/requests/resolvers.rb

@@ -123,11 +123,16 @@ module Requests
       when :https
 
         define_method :"test_resolver_#{resolver_type}_get_request" do
-          session = HTTPX.plugin(SessionWithPool)
+          HTTPX.plugin(SessionWithPool).wrap do |http|
             uri = build_uri("/get")
-          response = session.head(uri, resolver_class: resolver_type, resolver_options: options.merge(use_get: true))
+            response = http.head(uri, resolver_class: resolver_type, resolver_options: options.merge(use_get: true))
             verify_status(response, 200)
             response.close
+            resolver_uri = URI(options[:uri])
+            resolver_conn = http.pool.connections.find { |c| c.origin.to_s == resolver_uri.origin }
+            assert resolver_conn, "https resolver connection should still be there"
+            assert resolver_conn.open?, "resolver connection should be kept around open"
+          end
         end
 
         define_method :"test_resolver_#{resolver_type}_unresolvable_servername" do
@@ -188,16 +193,20 @@ module Requests
         end
 
         define_method :"test_resolver_#{resolver_type}_no_answers" do
-          session = HTTPX.plugin(SessionWithPool)
+          HTTPX.plugin(SessionWithPool).wrap do |http|
             uri = URI(build_uri("/get"))
             resolver_class = Class.new(HTTPX::Resolver::HTTPS) do
               def parse_addresses(_, request)
                 super([], request)
               end
             end
-          response = session.head(uri, resolver_class: resolver_class, resolver_options: options.merge(record_types: %w[]))
+            response = http.head(uri, resolver_class: resolver_class, resolver_options: options.merge(record_types: %w[]))
             verify_error_response(response, HTTPX::ResolveError)
-          assert session.pool.connections.size == 1, "https resolver connection should still be there"
+            resolver_uri = URI(options[:uri])
+            resolver_conn = http.pool.connections.find { |c| c.origin.to_s == resolver_uri.origin }
+            assert resolver_conn, "https resolver connection should still be there"
+            assert resolver_conn.state == :closed, "resolver connection should have closed after error"
+          end
         end
       when :native
         define_method :"test_resolver_#{resolver_type}_tcp_request" do