slave.cc try_to_reconnect remove retry_counter

`try_to_reconnect()` wraps `safe_reconnect()` with logging, but the
latter already loops reconnection attempts up to `master_retry_count`
times with `mi->connect_retry`-msec sleeps inbetween.
This means `try_to_reconnect()` has been counting disconnects of the
replication session (since it doesn’t loop) while `safe_reconnect()`
was counting actual tries (which may be multiple per disconnect).
In practice, this outer counter’s only benefit was to override the edge
case `--master-retry-count=0` that the inner loop doesn’t cover with 1.

Author: ParadoxV5

sql/slave.cc

@@ -112,38 +112,29 @@ enum enum_slave_reconnect_actions
 
 enum enum_slave_reconnect_messages
 {
-  SLAVE_RECON_MSG_WAIT= 0,
-  SLAVE_RECON_MSG_KILLED_WAITING= 1,
-  SLAVE_RECON_MSG_AFTER= 2,
-  SLAVE_RECON_MSG_FAILED= 3,
-  SLAVE_RECON_MSG_COMMAND= 4,
-  SLAVE_RECON_MSG_KILLED_AFTER= 5,
+  SLAVE_RECON_MSG_AFTER,
+  SLAVE_RECON_MSG_FAILED,
+  SLAVE_RECON_MSG_COMMAND,
+  SLAVE_RECON_MSG_KILLED_AFTER,
   SLAVE_RECON_MSG_MAX
 };
 
 static const char *reconnect_messages[SLAVE_RECON_ACT_MAX][SLAVE_RECON_MSG_MAX]=
 {
   {
-    "Waiting to reconnect after a failed registration on master",
-    "Slave I/O thread killed while waiting to reconnect after a failed \
-registration on master",
     "Reconnecting after a failed registration on master",
     "failed registering on master, reconnecting to try again, \
 log '%s' at position %llu%s",
     "COM_REGISTER_SLAVE",
     "Slave I/O thread killed during or after reconnect"
   },
   {
-    "Waiting to reconnect after a failed binlog dump request",
-    "Slave I/O thread killed while retrying master dump",
     "Reconnecting after a failed binlog dump request",
     "failed dump request, reconnecting to try again, log '%s' at position %llu%s",
     "COM_BINLOG_DUMP",
     "Slave I/O thread killed during or after reconnect"
   },
   {
-    "Waiting to reconnect after a failed master event read",
-    "Slave I/O thread killed while waiting to reconnect after a failed read",
     "Reconnecting after a failed master event read",
     "Slave I/O thread: Failed reading log event, reconnecting to retry, \
 log '%s' at position %llu%s",
@@ -4396,20 +4387,18 @@ static bool check_io_slave_killed(Master_info *mi, const char *info)
 /**
   @brief Try to reconnect slave IO thread.
 
-  @details Terminates current connection to master, sleeps for
-  @c mi->connect_retry msecs and initiates new connection with
-  @c safe_reconnect(). Variable pointed by @c retry_count is increased -
+  @details Terminates current connection to master
+  and initiates new connection with safe_reconnect(), which sleeps for
+  @c mi->connect_retry msecs and increases @c mi->TODO for each attempt -
   if it exceeds @c master_retry_count then connection is not re-established
   and function signals error.
   Unless @c suppres_warnings is TRUE, a warning is put in the server error log
   when reconnecting. The warning message and messages used to report errors
-  are taken from @c messages array. In case @c master_retry_count is exceeded,
-  no messages are added to the log.
+  are taken from @c messages array.
 
   @param[in]     thd                 Thread context.
   @param[in]     mysql               MySQL connection.
   @param[in]     mi                  Master connection information.
-  @param[in,out] retry_count         Number of attempts to reconnect.
   @param[in]     suppress_warnings   TRUE when a normal net read timeout
                                      has caused to reconnecting.
   @param[in]     messages            Messages to print/log, see 
@@ -4420,23 +4409,14 @@ static bool check_io_slave_killed(Master_info *mi, const char *info)
 */
 
 static int try_to_reconnect(THD *thd, MYSQL *mysql, Master_info *mi,
-                            uint *retry_count, bool suppress_warnings,
+                            bool suppress_warnings,
                             const char *messages[SLAVE_RECON_MSG_MAX])
 {
   mi->slave_running= MYSQL_SLAVE_RUN_NOT_CONNECT;
-  thd->proc_info= messages[SLAVE_RECON_MSG_WAIT];
 #ifdef SIGNAL_WITH_VIO_CLOSE  
   thd->clear_active_vio();
 #endif
   end_server(mysql);
-  if ((*retry_count)++)
-  {
-    if (*retry_count > master_retry_count)
-      return 1;                             // Don't retry forever
-    slave_sleep(thd, mi->connect_retry, io_slave_killed, mi);
-  }
-  if (check_io_slave_killed(mi, messages[SLAVE_RECON_MSG_KILLED_WAITING]))
-    return 1;
   thd->proc_info = messages[SLAVE_RECON_MSG_AFTER];
   if (!suppress_warnings) 
   {
@@ -4497,7 +4477,6 @@ pthread_handler_t handle_slave_io(void *arg)
   MYSQL *mysql;
   Master_info *mi = (Master_info*)arg;
   Relay_log_info *rli= &mi->rli;
-  uint retry_count;
   bool suppress_warnings;
   int ret;
   rpl_io_thread_info io_info;
@@ -4511,7 +4490,6 @@ pthread_handler_t handle_slave_io(void *arg)
 
   DBUG_ASSERT(mi->inited);
   mysql= NULL ;
-  retry_count= 0;
 
   thd= new THD(next_thread_id()); // note that contructor of THD uses DBUG_ !
 
@@ -4661,7 +4639,7 @@ pthread_handler_t handle_slave_io(void *arg)
       Try to reconnect because the error was caused by a transient network
       problem
     */
-    if (try_to_reconnect(thd, mysql, mi, &retry_count, suppress_warnings,
+    if (try_to_reconnect(thd, mysql, mi, suppress_warnings,
                              reconnect_messages[SLAVE_RECON_ACT_REG]))
       goto err;
 
@@ -4678,7 +4656,7 @@ pthread_handler_t handle_slave_io(void *arg)
                               "while registering slave on master"))
     {
       sql_print_error("Slave I/O thread couldn't register on master");
-      if (try_to_reconnect(thd, mysql, mi, &retry_count, suppress_warnings,
+      if (try_to_reconnect(thd, mysql, mi, suppress_warnings,
                            reconnect_messages[SLAVE_RECON_ACT_REG]))
         goto err;
     }
@@ -4705,7 +4683,7 @@ pthread_handler_t handle_slave_io(void *arg)
     {
       sql_print_error("Failed on request_dump()");
       if (check_io_slave_killed(mi, NullS) ||
-        try_to_reconnect(thd, mysql, mi, &retry_count, suppress_warnings,
+        try_to_reconnect(thd, mysql, mi, suppress_warnings,
                          reconnect_messages[SLAVE_RECON_ACT_DUMP]))
         goto err;
       goto connected;
@@ -4764,13 +4742,12 @@ Stopping slave I/O thread due to out-of-memory error from master");
                      "%s", ER_THD(thd, ER_OUT_OF_RESOURCES));
           goto err;
         }
-        if (try_to_reconnect(thd, mysql, mi, &retry_count, suppress_warnings,
+        if (try_to_reconnect(thd, mysql, mi, suppress_warnings,
                              reconnect_messages[SLAVE_RECON_ACT_EVENT]))
           goto err;
         goto connected;
       } // if (event_len == packet_error)
 
-      retry_count=0;                    // ok event, reset retry counter
       thd->set_time_for_next_stage();
       THD_STAGE_INFO(thd, stage_queueing_master_event_to_the_relay_log);
       event_buf= mysql->net.read_pos + 1;