extern int mysqld_main(int argc, char **argv);int main(int argc, char **argv)
{return mysqld_main(argc, argv);
}

int mysqld_main(int argc, char **argv)
{//创建服务监听线程handle_connections_sockets();
}void handle_connections_sockets()
{//监听连接new_sock= mysql_socket_accept(key_socket_client_connection, sock,(struct sockaddr *)(&cAddr), &length);if (mysql_socket_getfd(sock) == mysql_socket_getfd(unix_sock))thd->security_ctx->set_host((char*) my_localhost);//创建连接create_new_thread(thd);
}//创建新线程处理处理用户连接
static void create_new_thread(THD *thd){thd->thread_id= thd->variables.pseudo_thread_id= thread_id++;//线程进了线程调度器MYSQL_CALLBACK(thread_scheduler, add_connection, (thd));   
}

static scheduler_functions one_thread_per_connection_scheduler_functions=
{0,                                     // max_threadsNULL,                                  // initinit_new_connection_handler_thread,    // init_new_connection_threadcreate_thread_to_handle_connection,    // add_connectionNULL,                                  // thd_wait_beginNULL,                                  // thd_wait_endNULL,                                  // post_kill_notificationone_thread_per_connection_end,         // end_threadNULL,                                  // end
};

void create_thread_to_handle_connection(THD *thd)
{if ((error= mysql_thread_create(key_thread_one_connection, &thd->real_id, &connection_attrib,handle_one_connection,(void*) thd))){}
}
//触发回调函数  handle_one_connection
pthread_handler_t handle_one_connection(void *arg)
{do_handle_one_connection(thd);
}
//继续处理
void do_handle_one_connection(THD *thd_arg){while (thd_is_connection_alive(thd)){mysql_audit_release(thd);if (do_command(thd))  break;  //这里的 do_command 继续处理}
}
//继续分发
bool do_command(THD *thd)
{return_value= dispatch_command(command, thd, packet+1, (uint) (packet_length-1));
}
bool dispatch_command(enum enum_server_command command, THD *thd, char* packet, uint packet_length)
{switch (command) {case COM_INIT_DB: ....  break;...case COM_QUERY:   //查询语句：  insert xxxxmysql_parse(thd, thd->query(), thd->query_length(), &parser_state);  //sql解析break;}
}
//sql解析模块
void mysql_parse(THD *thd, char *rawbuf, uint length, Parser_state *parser_state)
{error= mysql_execute_command(thd);
}

//继续执行
int mysql_execute_command(THD *thd)
{switch (lex->sql_command) {case SQLCOM_SELECT:  res= execute_sqlcom_select(thd, all_tables);  break;//这个 insert 就是我要追的case SQLCOM_INSERT:   res= mysql_insert(thd, all_tables, lex->field_list, lex->many_values,lex->update_list, lex->value_list,lex->duplicates, lex->ignore);}
}
//insert插入操作处理
bool mysql_insert(THD *thd,TABLE_LIST *table_list,List<Item> &fields, List<List_item> &values_list,List<Item> &update_fields, List<Item> &update_values, enum_duplicates duplic, bool ignore)
{while ((values= its++)){error= write_record(thd, table, &info, &update);}
}
//写入记录
int write_record(THD *thd, TABLE *table, COPY_INFO *info, COPY_INFO *update)
{if (duplicate_handling == DUP_REPLACE || duplicate_handling == DUP_UPDATE){// ha_write_row  重点是这个函数while ((error=table->file->ha_write_row(table->record[0]))){....}}
}

int handler::ha_write_row(uchar *buf)
{MYSQL_TABLE_IO_WAIT(m_psi, PSI_TABLE_WRITE_ROW, MAX_KEY, 0,{ error= write_row(buf); })
}//这是一个虚方法
virtual int write_row(uchar *buf __attribute__((unused)))
{return HA_ERR_WRONG_COMMAND;
}