BUG#19402 SQL close to the size of the max_allowed_packet fails on the slave

A communication packet can also be a binlog event sent from the master to the slave.
To be sent by master dump and accepted by slave io thread both have to have
the value of max_allowed_packet bigger than one that client connection had.

In the patch there is the MAX possible replicatio header size estimation for events
in binlog that embedded user query. Only these events of query_log_event type, i.e
just plain queries, require attention. 


sql/log_event.h:
  MAX value of the header of the replication packet, i.e the value of exceeding
  the query string part.
sql/slave.cc:
  Private value of max allowed packet slave io, sql threads can accept from master.
  The value is increased by the MAX possible size of replication event header.
  
  Note, that my_net_init is redundant for slave io because the thread uses instance of
  NET struct, embedded into MYSQL, as a client to server. We have left old code and even
  increment, redundantly as well, thd->net.max_packet_size just for the sake of
  consistency. TODO: eliminate my_net_init from execution path of slave io.
sql/sql_repl.cc:
  Increasing the private max allowed packet that the dump thread reads from master
  binlog and sends to net. Note, that happened prior this writting to binlog is
  safe from the current artifact because it is done by steps that each chunk can not
  exceed @@global.max_allowed_packet.
mysql-test/r/rpl_packet.result:
  BitKeeper file /home/elkin/MySQL/TEAM/FIXES/4.1/bug19402-max_allowed/mysql-test/r/rpl_packet.result
mysql-test/t/rpl_packet-master.opt:
  BitKeeper file /net/koti/usr_rh9/home/elkin.rh9/MySQL/TEAM/FIXES/4.1/bug19402-max_allowed/mysql-test/t/rpl_packet-master.opt
mysql-test/t/rpl_packet-slave.opt:
  BitKeeper file /net/koti/usr_rh9/home/elkin.rh9/MySQL/TEAM/FIXES/4.1/bug19402-max_allowed/mysql-test/t/rpl_packet-slave.opt
mysql-test/t/rpl_packet.test:
  test examines repliation of a max-sized query when database name is set to have
  NAME_LEN bytes. This makes replication header size the maximum.

mysql-test/r/rpl_packet.result

+stop slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+reset master;
+reset slave;
+drop table if exists t1,t2,t3,t4,t5,t6,t7,t8,t9;
+start slave;
+select @@net_buffer_length, @@max_allowed_packet;
+@@net_buffer_length	@@max_allowed_packet
+1024	1024
+drop database if exists DB_NAME_OF_MAX_LENGTH_AKA_NAME_LEN_64_BYTES_____________________;
+Warnings:
+Note	1008	Can't drop database 'DB_NAME_OF_MAX_LENGTH_AKA_NAME_LEN_64_BYTES_____________________'; database doesn't exist
+create database DB_NAME_OF_MAX_LENGTH_AKA_NAME_LEN_64_BYTES_____________________;
+create table `t1` (`f1` LONGTEXT) ENGINE=MyISAM;
+INSERT INTO `t1`(`f1`) VALUES ('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1023');
+INSERT INTO `t1`(`f1`) VALUES ('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1024');
+ERROR 08S01: Got a packet bigger than 'max_allowed_packet' bytes
+select count(*) from `t1` /* must be 1 */;
+count(*)
+1
+drop database DB_NAME_OF_MAX_LENGTH_AKA_NAME_LEN_64_BYTES_____________________;

mysql-test/t/rpl_packet-master.opt

+-O max_allowed_packet=1024 -O net_buffer_length=1024

mysql-test/t/rpl_packet-slave.opt

+-O max_allowed_packet=1024 -O net_buffer_length=1024

mysql-test/t/rpl_packet.test

+#
+# Check replication protocol packet size handling
+# Bug#19402 SQL close to the size of the max_allowed_packet fails on slave
+#
+
+# max-out size db name 
+source include/master-slave.inc;
+
+let $db= DB_NAME_OF_MAX_LENGTH_AKA_NAME_LEN_64_BYTES_____________________;
+
+connection master;
+select @@net_buffer_length, @@max_allowed_packet;
+eval drop database if exists $db;
+eval create database $db;
+
+# alas, can't use eval here
+connect (master1,localhost,root,,DB_NAME_OF_MAX_LENGTH_AKA_NAME_LEN_64_BYTES_____________________);
+
+connection master1;
+create table `t1` (`f1` LONGTEXT) ENGINE=MyISAM;
+
+INSERT INTO `t1`(`f1`) VALUES ('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1023');
+
+--error 1153
+INSERT INTO `t1`(`f1`) VALUES ('aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa1024');
+
+save_master_pos;
+
+connection slave;
+sync_with_master;
+select count(*) from `t1` /* must be 1 */;
+
+connection master1;
+eval drop database $db;
+save_master_pos;
+
+connection slave;
+sync_with_master;
+
+# End of tests

sql/log_event.h

@@ -147,6 +147,12 @@ struct sql_ex_info
 #define EXEC_LOAD_HEADER_LEN   4
 #define DELETE_FILE_HEADER_LEN 4
 
+/* amount of byte is contribution of replicaton protocol to a query
+   received from user when the query goes to binlog */
+#define MAX_LOG_EVENT_HEADER   (LOG_EVENT_HEADER_LEN + /* write_header */ \
+				QUERY_HEADER_LEN     + /* write_data */   \
+				NAME_LEN + 1)
+
 /* 
    Event header offsets; 
    these point to places inside the fixed header.

sql/slave.cc

@@ -2618,6 +2618,8 @@ static int init_slave_thread(THD* thd, SLAVE_THD_TYPE thd_type)
     SYSTEM_THREAD_SLAVE_SQL : SYSTEM_THREAD_SLAVE_IO; 
   thd->host_or_ip= "";
   my_net_init(&thd->net, 0);
+  thd->variables.max_allowed_packet= global_system_variables.max_allowed_packet
+    + MAX_LOG_EVENT_HEADER;  /* reentering secured through using global */
   thd->net.read_timeout = slave_net_timeout;
   thd->master_access= ~(ulong)0;
   thd->priv_user = 0;
@@ -3143,16 +3145,20 @@ extern "C" pthread_handler_decl(handle_slave_io,arg)
     sql_print_error("Slave I/O thread: error in mysql_init()");
     goto err;
   }
-  
+
 
   thd->proc_info = "Connecting to master";
   // we can get killed during safe_connect
   if (!safe_connect(thd, mysql, mi))
+  {
     sql_print_information("Slave I/O thread: connected to master '%s@%s:%d',\
   replication started in log '%s' at position %s", mi->user,
-		    mi->host, mi->port,
-		    IO_RPL_LOG_NAME,
-		    llstr(mi->master_log_pos,llbuff));
+			  mi->host, mi->port,
+			  IO_RPL_LOG_NAME,
+			  llstr(mi->master_log_pos,llbuff));
+    /* post-net-init for slave */
+    mysql->net.max_packet_size= thd->net.max_packet_size+= MAX_LOG_EVENT_HEADER;
+  }
   else
   {
     sql_print_error("Slave I/O thread killed while connecting to master");

sql/sql_repl.cc

@@ -420,6 +420,8 @@ impossible position";
     goto err;
   }
   packet->set("\0", 1, &my_charset_bin);
+  /* dump thread  the whole header size of query_log_event */
+  thd->variables.max_allowed_packet+= MAX_LOG_EVENT_HEADER;
 
   while (!net->error && net->vio != 0 && !thd->killed)
   {