Use vio_is_connected to check connected state

.rubocop.yml

@@ -26,3 +26,10 @@ Style/TrailingCommaInLiteral:
 
 Style/TrivialAccessors:
   AllowPredicates: true
+
+Metrics/BlockLength:
+  Exclude:
+    - 'benchmark/setup_db.rb'
+    - '**/*.rake'
+    - 'spec/spec_helper.rb'
+    - 'spec/**/*_spec.rb'

.rubocop_todo.yml

@@ -19,11 +19,6 @@ Layout/IndentHeredoc:
 Metrics/AbcSize:
   Max: 90
 
-# Offense count: 31
-# Configuration parameters: CountComments, ExcludedMethods.
-Metrics/BlockLength:
-  Max: 860
-
 # Offense count: 1
 # Configuration parameters: CountBlocks.
 Metrics/BlockNesting:

ext/mysql2/client.c

@@ -16,7 +16,7 @@
 
 VALUE cMysql2Client;
 extern VALUE mMysql2, cMysql2Error, cMysql2TimeoutError;
-static VALUE sym_id, sym_version, sym_header_version, sym_async, sym_symbolize_keys, sym_as, sym_array, sym_stream;
+static VALUE sym_id, sym_version, sym_header_version, sym_async, sym_symbolize_keys, sym_as, sym_array, sym_stream, sym_has_vio_is_connected;
 static VALUE sym_no_good_index_used, sym_no_index_used, sym_query_was_slow;
 static ID intern_brackets, intern_merge, intern_merge_bang, intern_new_with_args;
 
@@ -25,10 +25,17 @@ static ID intern_brackets, intern_merge, intern_merge_bang, intern_new_with_args
     rb_raise(cMysql2Error, "MySQL client is not initialized"); \
   }
 
+#if defined(HAVE_VIO_IS_CONNECTED)
+ my_bool vio_is_connected(Vio *vio);
+ #define VIO_IS_CONNECTED(wrapper) vio_is_connected(wrapper->client->net.vio)
+#else
+ #define VIO_IS_CONNECTED(wrapper) 1
+#endif
+
 #if defined(HAVE_MYSQL_NET_VIO) || defined(HAVE_ST_NET_VIO)
-  #define CONNECTED(wrapper) (wrapper->client->net.vio != NULL && wrapper->client->net.fd != -1)
+  #define CONNECTED(wrapper) (wrapper->client->net.vio != NULL && wrapper->client->net.fd != -1 && VIO_IS_CONNECTED(wrapper))
 #elif defined(HAVE_MYSQL_NET_PVIO) || defined(HAVE_ST_NET_PVIO)
-  #define CONNECTED(wrapper) (wrapper->client->net.pvio != NULL && wrapper->client->net.fd != -1)
+  #define CONNECTED(wrapper) (wrapper->client->net.pvio != NULL && wrapper->client->net.fd != -1 && VIO_IS_CONNECTED(wrapper))
 #endif
 
 #define REQUIRE_CONNECTED(wrapper) \
@@ -946,6 +953,11 @@ static VALUE _mysql_client_options(VALUE self, int opt, VALUE value) {
  */
 static VALUE rb_mysql_client_info(RB_MYSQL_UNUSED VALUE klass) {
   VALUE version_info, version, header_version;
+#if defined(HAVE_VIO_IS_CONNECTED)
+  VALUE has_vio_is_connected = Qtrue;
+#else
+  VALUE has_vio_is_connected = Qfalse;
+#endif
   version_info = rb_hash_new();
 
   version = rb_str_new2(mysql_get_client_info());
@@ -957,6 +969,7 @@ static VALUE rb_mysql_client_info(RB_MYSQL_UNUSED VALUE klass) {
   rb_hash_aset(version_info, sym_id, LONG2NUM(mysql_get_client_version()));
   rb_hash_aset(version_info, sym_version, version);
   rb_hash_aset(version_info, sym_header_version, header_version);
+  rb_hash_aset(version_info, sym_has_vio_is_connected, has_vio_is_connected);
 
   return version_info;
 }
@@ -1454,14 +1467,15 @@ void init_mysql2_client() {
   rb_define_private_method(cMysql2Client, "connect", rb_mysql_connect, 8);
   rb_define_private_method(cMysql2Client, "_query", rb_mysql_query, 2);
 
-  sym_id              = ID2SYM(rb_intern("id"));
-  sym_version         = ID2SYM(rb_intern("version"));
-  sym_header_version  = ID2SYM(rb_intern("header_version"));
-  sym_async           = ID2SYM(rb_intern("async"));
-  sym_symbolize_keys  = ID2SYM(rb_intern("symbolize_keys"));
-  sym_as              = ID2SYM(rb_intern("as"));
-  sym_array           = ID2SYM(rb_intern("array"));
-  sym_stream          = ID2SYM(rb_intern("stream"));
+  sym_id                   = ID2SYM(rb_intern("id"));
+  sym_version              = ID2SYM(rb_intern("version"));
+  sym_header_version       = ID2SYM(rb_intern("header_version"));
+  sym_async                = ID2SYM(rb_intern("async"));
+  sym_symbolize_keys       = ID2SYM(rb_intern("symbolize_keys"));
+  sym_as                   = ID2SYM(rb_intern("as"));
+  sym_array                = ID2SYM(rb_intern("array"));
+  sym_stream               = ID2SYM(rb_intern("stream"));
+  sym_has_vio_is_connected = ID2SYM(rb_intern("has_vio_is_connected"));
 
   sym_no_good_index_used = ID2SYM(rb_intern("no_good_index_used"));
   sym_no_index_used      = ID2SYM(rb_intern("no_index_used"));

ext/mysql2/extconf.rb

@@ -106,6 +106,7 @@ def add_ssl_defines(header)
 add_ssl_defines(mysql_h)
 have_struct_member('MYSQL', 'net.vio', mysql_h)
 have_struct_member('MYSQL', 'net.pvio', mysql_h)
+have_func('vio_is_connected')
 
 # These constants are actually enums, so they cannot be detected by #ifdef in C code.
 have_const('MYSQL_ENABLE_CLEARTEXT_PLUGIN', mysql_h)

spec/mysql2/client_spec.rb

@@ -342,6 +342,20 @@ def run_gc
       @client.close
       expect(@client.closed?).to eql(true)
     end
+
+    it "should detect a closed connection" do
+      skip "libmysqlclient does not export vio_is_connected()" unless Mysql2::Client.info[:has_vio_is_connected]
+      connection_id = @client.thread_id
+      Thread.new do
+        sleep(0.1)
+        Mysql2::Client.new(DatabaseCredentials['root']).tap do |supervisor|
+          supervisor.query("KILL #{connection_id}")
+        end.close
+      end
+      expect(@client.query("SELECT 1").first["1"]).to eql(1)
+      sleep(0.2)
+      expect(@client.closed?).to be true
+    end
   end
 
   it "should not try to query closed mysql connection" do
@@ -573,7 +587,7 @@ def run_gc
       end
       expect do
         @client.query("SELECT SLEEP(1)")
-      end.to raise_error(Mysql2::Error, /Lost connection to MySQL server/)
+      end.to raise_error(Mysql2::Error)
 
       if RUBY_PLATFORM !~ /mingw|mswin/
         expect do