misc. sql/slave.cc & co. refactor

* `get_master_version_and_clock()` de-duplicate label using fall-through * `io_slave_killed()` & `check_io_slave_killed()`: * reüse the result from the level lower * add distinguishing docs * `try_to_reconnect()`: extract `'` from `if`-`else` * `handle_slave_io()`: Both `while`s have the same condition; looks like the outer `while` can simply be an `if`. * `connect_to_master()`: * assume `mysql_errno()` is not 0 on connection error * utilize 0’s falsiness in the loop * extend docs * `sql/sql_show.cc`: refactor SHOW ALL REPLICAS filter’s condition * `sql/mysqld.cc`: init `master-retry-count` with `master_retry_count` Reviewed-by: Kristian Nielsen <knielsen@knielsen-hq.org>

Author: ParadoxV5

mysql-test/include/check-testcase.inc

@@ -163,4 +163,3 @@ if (`SELECT COUNT(*)=1 FROM INFORMATION_SCHEMA.PLUGINS WHERE PLUGIN_NAME = 'wsre
 }
 
 --enable_query_log
-

sql/mysqld.cc

@@ -778,9 +778,9 @@ mysql_cond_t COND_server_started;
 int mysqld_server_started=0, mysqld_server_initialized= 0;
 File_parser_dummy_hook file_parser_dummy_hook;
 
-/* replication parameters, if master_host is not NULL, we are a slave */
+/* replication parameters */
 uint report_port= 0;
-ulong master_retry_count=0;
+ulong master_retry_count=100000;
 char *master_info_file;
 char *relay_log_info_file, *report_user, *report_password, *report_host;
 char *opt_relay_logname = 0, *opt_relaylog_index_name=0;
@@ -6817,7 +6817,7 @@ struct my_option my_long_options[]=
  {"master-retry-count", 0,
  "The number of tries the slave will make to connect to the master before giving up",
  &master_retry_count, &master_retry_count, 0, GET_ULONG,
- REQUIRED_ARG, 100000, 0, 0, 0, 0, 0},
+ REQUIRED_ARG, static_cast<longlong>(master_retry_count), 0, 0, 0, 0, 0},
 #ifdef HAVE_REPLICATION
  {"init-rpl-role", 0, "Set the replication role",
  &rpl_status, &rpl_status, &rpl_role_typelib,

sql/slave.cc

@@ -1308,14 +1308,15 @@ void end_slave()
  DBUG_VOID_RETURN;
 }
 
+/** @return whether the slave's Master_info is marked as killed */
 static bool io_slave_killed(Master_info* mi)
 {
  DBUG_ENTER("io_slave_killed");
-
  DBUG_ASSERT(mi->slave_running); // tracking buffer overrun
- if (mi->abort_slave || mi->io_thd->killed)
+ bool is_io_slave_killed= mi->abort_slave || mi->io_thd->killed;
+ if (is_io_slave_killed)
  DBUG_PRINT("info", ("killed"));
- DBUG_RETURN(mi->abort_slave || mi->io_thd->killed);
+ DBUG_RETURN(is_io_slave_killed);
 }
 
 /**
@@ -2600,10 +2601,6 @@ when it try to get the value of TIME_ZONE global variable from master.";
  DBUG_RETURN(0);
 
 network_err:
- if (master_res)
- mysql_free_result(master_res);
- DBUG_RETURN(2);
-
 slave_killed_err:
  if (master_res)
  mysql_free_result(master_res);
@@ -4377,15 +4374,13 @@ on this slave.\
 }
 
 
+/** Return io_slave_killed(); if it's `true`, also log the given `info`. */
 static bool check_io_slave_killed(Master_info *mi, const char *info)
 {
- if (io_slave_killed(mi))
- {
- if (info && global_system_variables.log_warnings)
- sql_print_information("%s", info);
- return TRUE;
- }
- return FALSE;
+ bool is_io_slave_killed= io_slave_killed(mi);
+ if (is_io_slave_killed && info && global_system_variables.log_warnings)
+ sql_print_information("%s", info);
+ return is_io_slave_killed;
 }
 
 /**
@@ -4430,11 +4425,10 @@ static int try_to_reconnect(THD *thd, MYSQL *mysql, Master_info *mi,
  {
  tmp.append(STRING_WITH_LEN("; GTID position '"));
  mi->gtid_current_pos.append_to_string(&tmp);
- if (mi->events_queued_since_last_gtid == 0)
- tmp.append(STRING_WITH_LEN("'"));
- else
+ tmp.append('\'');
+ if (mi->events_queued_since_last_gtid)
  {
- tmp.append(STRING_WITH_LEN("', GTID event skip "));
+ tmp.append(STRING_WITH_LEN(", GTID event skip "));
  tmp.append_ulonglong((ulonglong)mi->events_queued_since_last_gtid);
  }
  }
@@ -4678,7 +4672,7 @@ pthread_handler_t handle_slave_io(void *arg)
 
  DBUG_PRINT("info",("Starting reading binary log from master"));
  thd->set_command(COM_SLAVE_IO);
- while (!io_slave_killed(mi))
+ if (!io_slave_killed(mi))
  {
  const uchar *event_buf;
 
@@ -6931,20 +6925,21 @@ static int safe_connect(THD* thd, MYSQL* mysql, Master_info* mi)
 }
 
 
-/*
- SYNPOSIS
- connect_to_master()
-
- IMPLEMENTATION
- Try to connect until successful or slave killed or we have retried
- mi->retry_count times
+/**
+ @brief Re/connect to the master `mi`
+ @details
+ After preparations and config validations,
+ this repeatedly calls the low-level connection function (and logs statuses)
+ up to mi->retry_count times until success or when io_slave_killed().
+ @param reconnect
+ whether this connection is a new first-time or reconnects an existing one
+ @return errno: 1 if error or 0 if successful
 */
-
 static int connect_to_master(THD* thd, MYSQL* mysql, Master_info* mi,
  bool reconnect, bool suppress_warnings)
 {
  int slave_was_killed;
- int last_errno= -2; // impossible error
+ unsigned int last_errno= 0; // initialize with not-error
  mi->connects_tried= 0; // reset retry counter
  my_bool my_true= 1;
  DBUG_ENTER("connect_to_master");
@@ -7005,13 +7000,13 @@ static int connect_to_master(THD* thd, MYSQL* mysql, Master_info* mi,
  "terminated.");
  DBUG_RETURN(1);
  }
- while (!(slave_was_killed = io_slave_killed(mi)) &&
- (reconnect ? mysql_reconnect(mysql) != 0 :
- mysql_real_connect(mysql, mi->host, mi->user, mi->password, 0,
- mi->port, 0, client_flag) == 0))
+ while (!(slave_was_killed= io_slave_killed(mi)) &&
+ (reconnect ? mysql_reconnect(mysql) :
+ !mysql_real_connect(mysql, mi->host, mi->user, mi->password, 0,
+  mi->port, 0, client_flag)))
  {
- /* Don't repeat last error */
- if ((int)mysql_errno(mysql) != last_errno && !io_slave_killed(mi))
+ /* Don't repeat last error and don't report killed error */
+ if (mysql_errno(mysql) != last_errno && !io_slave_killed(mi))
  {
  last_errno=mysql_errno(mysql);
  suppress_warnings= 0;

sql/sql_show.cc

@@ -9226,18 +9226,12 @@ static int make_slave_status_old_format(THD *thd, ST_SCHEMA_TABLE *schema_table)
  for (uint i=0; !field_info->end_marker(); field_info++, i++)
  {
  if (all_slaves ||
- // not SLAVE_STATUS_COL_CONNECTION_NAME,
- // SLAVE_STATUS_COL_SLAVE_SQL_STATE
- // and less
- // SLAVE_STATUS_COL_RETRIED_TRANSACTIONS
- !(i <= SLAVE_STATUS_COL_SLAVE_SQL_STATE ||
- i >= SLAVE_STATUS_COL_RETRIED_TRANSACTIONS))
+ (i > SLAVE_STATUS_COL_SLAVE_SQL_STATE &&
+ i < SLAVE_STATUS_COL_RETRIED_TRANSACTIONS))
  {
  LEX_CSTRING field_name= field_info->name();
  Item_field *field= new (thd->mem_root)
  Item_field(thd, context, field_name);
- DBUG_ASSERT(all_slaves || (i > SLAVE_STATUS_COL_SLAVE_SQL_STATE &&
- i < SLAVE_STATUS_COL_RETRIED_TRANSACTIONS));
  if (!field || add_item_to_list(thd, field))
  return 1;
  }