Save connection options for conn.reset

Commit 016c17c introduced a regression, that leads to a host list duplication every time conn.reset is used.

Since the hosts are duplicated when resolve_hosts is called, the conn.coninfo_hash can not be used.
So the fix is to store the original hash of connection options for later use in conn.reset .

Fixes #586

ext/pg_connection.c

@@ -264,6 +264,7 @@ pgconn_s_allocate( VALUE klass )
 	RB_OBJ_WRITE(self, &this->decoder_for_get_copy_data, Qnil);
 	RB_OBJ_WRITE(self, &this->trace_stream, Qnil);
 	rb_ivar_set(self, rb_intern("@calls_to_put_copy_data"), INT2FIX(0));
+	rb_ivar_set(self, rb_intern("@iopts_for_reset"), Qnil);
 
 	return self;
 }

lib/pg/connection.rb

@@ -573,7 +573,9 @@ def encrypt_password( password, username, algorithm=nil )
 	# Resets the backend connection. This method closes the
 	# backend connection and tries to re-connect.
 	def reset
-		iopts = conninfo_hash.compact
+		# Use connection options from PG::Connection.new to reconnect with the same options but with renewed DNS resolution.
+		# Use conninfo_hash as a fallback when connect_start was used to create the connection object.
+		iopts = @iopts_for_reset || conninfo_hash.compact
 		if iopts[:host] && !iopts[:host].empty? && PG.library_version >= 100000
 			iopts = self.class.send(:resolve_hosts, iopts)
 		end
@@ -825,6 +827,7 @@ def new(*args)
 			iopts = PG::Connection.conninfo_parse(option_string).each_with_object({}){|h, o| o[h[:keyword].to_sym] = h[:val] if h[:val] }
 			iopts = PG::Connection.conndefaults.each_with_object({}){|h, o| o[h[:keyword].to_sym] = h[:val] if h[:val] }.merge(iopts)
 
+			iopts_for_reset = iopts
 			if iopts[:hostaddr]
 				# hostaddr is provided -> no need to resolve hostnames
 
@@ -838,6 +841,8 @@ def new(*args)
 
 			raise PG::ConnectionBad, conn.error_message if conn.status == PG::CONNECTION_BAD
 
+			# save the connection options for conn.reset
+			conn.instance_variable_set(:@iopts_for_reset, iopts_for_reset)
 			conn.send(:async_connect_or_reset, :connect_poll)
 			conn
 		end

spec/helpers.rb

@@ -678,8 +678,8 @@ def with_env_vars(**kwargs)
 	end
 
 	# Append or change 'rubypg_test' host entry in /etc/hosts to a given IP address
-	def set_etc_hosts(hostaddr)
-		system "sudo --non-interactive sed -i '/.* rubypg_test$/{h;s/.*/#{hostaddr} rubypg_test/};${x;/^$/{s//#{hostaddr} rubypg_test/;H};x}' /etc/hosts" or skip("unable to change /etc/hosts file")
+	def set_etc_hosts(hostaddr, hostname)
+		system "sudo --non-interactive sed -i '/.* #{hostname}$/{h;s/.*/#{hostaddr} #{hostname}/};${x;/^$/{s//#{hostaddr} #{hostname}/;H};x}' /etc/hosts" or skip("unable to change /etc/hosts file")
 	end
 end
 

spec/pg/connection_async_spec.rb

@@ -135,4 +135,25 @@ def interrupt_thread(exc=nil)
 		end
 	end
 
+	it "doesn't duplicate hosts in conn.reset", :without_transaction, :ipv6, :postgresql_10 do
+		set_etc_hosts "::1", "rubypg_test2 rubypg_test_ipv6"
+		set_etc_hosts "127.0.0.1", "rubypg_test2 rubypg_test_ipv4"
+		conn = described_class.connect( "postgres://rubypg_test2/test" )
+		conn.exec("select 1")
+		expect( conn.conninfo_hash[:host] ).to eq( "rubypg_test2,rubypg_test2" )
+		expect( conn.conninfo_hash[:hostaddr] ).to eq( "::1,127.0.0.1" )
+		expect( conn.conninfo_hash[:port] ).to eq( "#{@port},#{@port}" )
+		expect( conn.host ).to eq( "rubypg_test2" )
+		expect( conn.hostaddr ).to eq( "::1" )
+		expect( conn.port ).to eq( @port )
+
+		conn.reset
+		conn.exec("select 2")
+		expect( conn.conninfo_hash[:host] ).to eq( "rubypg_test2,rubypg_test2" )
+		expect( conn.conninfo_hash[:hostaddr] ).to eq( "::1,127.0.0.1" )
+		expect( conn.conninfo_hash[:port] ).to eq( "#{@port},#{@port}" )
+		expect( conn.host ).to eq( "rubypg_test2" )
+		expect( conn.hostaddr ).to eq( "::1" )
+		expect( conn.port ).to eq( @port )
+	end
 end

spec/pg/connection_spec.rb

@@ -1728,15 +1728,15 @@
 	end
 
 	it "refreshes DNS address while conn.reset", :without_transaction, :ipv6 do
-		set_etc_hosts "::1"
-		conn = described_class.connect( "postgres://rubypg_test/test" )
+		set_etc_hosts "::1", "rubypg_test1"
+		conn = described_class.connect( "postgres://rubypg_test1/test" )
 		conn.exec("select 1")
 
-		set_etc_hosts "127.0.0.1"
+		set_etc_hosts "127.0.0.1", "rubypg_test1"
 		conn.reset
 		conn.exec("select 1")
 
-		set_etc_hosts "::2"
+		set_etc_hosts "::2", "rubypg_test1"
 		expect do
 			conn.reset
 			conn.exec("select 1")