mariadb/sql/rpl_utility.h

/*
   Copyright (c) 2006, 2010, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1335  USA */

#ifndef RPL_UTILITY_H
#define RPL_UTILITY_H

#ifndef __cplusplus
#error "Don't include this C++ header file from a non-C++ file!"
#endif

#include "sql_priv.h"
#include "m_string.h"                           /* bzero, memcpy */
#ifdef MYSQL_SERVER
#include "table.h"                              /* TABLE_LIST */
#endif
#include "mysql_com.h"

class Relay_log_info;
class Log_event;
class Rows_log_event;
struct rpl_group_info;
struct RPL_TABLE_LIST;

/**
  A table definition from the master.

  The responsibilities of this class is:
  - Extract and decode table definition data from the table map event
  - Check if table definition in table map is compatible with table
    definition on slave
 */

class table_def
{
  table_def(const table_def&) = default;
public:
  /**
    Constructor.

    @param types Array of types, each stored as a byte
    @param size  Number of elements in array 'types'
    @param field_metadata Array of extra information about fields
    @param metadata_size Size of the field_metadata array
    @param null_bitmap The bitmap of fields that can be null
    @param optional_metadata Optional metadata logged into Table Map Event
                             when binlog_row_metadata=FULL on master
    @param optional_metadata_len Length of optional_metadata
   */
  table_def(unsigned char *types, ulong size, uchar *field_metadata,
            int metadata_size, uchar *null_bitmap, uint16 flags,
            const uchar *optional_metadata, uint optional_metadata_len);


  /**
    Move constructor
    Since it deallocates a memory during destruction, we can't safely copy it.
    We should instead move it to zero m_memory in an old object
   */
  table_def(table_def &&tabledef)
  : table_def(tabledef)
  {
    tabledef.m_memory= NULL;
  }

  ~table_def();

  /**
    Return the number of fields there is type data for.

    @return The number of fields that there is type data for.
   */
  inline ulong size() const { return m_size; }


  /**
    Returns internal binlog type code for one field,
    without translation to real types.
  */
  enum_field_types binlog_type(ulong index) const
  {
    return static_cast<enum_field_types>(m_type[index]);
  }
  /*
    Return a representation of the type data for one field.

    @param index Field index to return data for

    @return Will return a representation of the type data for field
    <code>index</code>. Currently, only the type identifier is
    returned.
   */
  enum_field_types type(ulong index) const
  {
    DBUG_ASSERT(index < m_size);
    /*
      If the source type is MYSQL_TYPE_STRING, it can in reality be
      either MYSQL_TYPE_STRING, MYSQL_TYPE_ENUM, or MYSQL_TYPE_SET, so
      we might need to modify the type to get the real type.
    */
    enum_field_types source_type= binlog_type(index);
    uint16 source_metadata= m_field_metadata[index];
    switch (source_type)
    {
    case MYSQL_TYPE_STRING:
    {
      int real_type= source_metadata >> 8;
      if (real_type == MYSQL_TYPE_ENUM || real_type == MYSQL_TYPE_SET)
        source_type= static_cast<enum_field_types>(real_type);
      break;
    }

    /*
      This type has not been used since before row-based replication,
      so we can safely assume that it really is MYSQL_TYPE_NEWDATE.
    */
    case MYSQL_TYPE_DATE:
      source_type= MYSQL_TYPE_NEWDATE;
      break;

    default:
      /* Do nothing */
      break;
    }

    return source_type;
  }
#ifdef MYSQL_SERVER
  const Type_handler *field_type_handler(uint index) const;
#endif

  /*
    This function allows callers to get the extra field data from the
    table map for a given field. If there is no metadata for that field
    or there is no extra metadata at all, the function returns 0.

    The function returns the value for the field metadata for column at 
    position indicated by index. As mentioned, if the field was a type 
    that stores field metadata, that value is returned else zero (0) is 
    returned. This method is used in the unpack() methods of the 
    corresponding fields to properly extract the data from the binary log 
    in the event that the master's field is smaller than the slave.
  */
  uint16 field_metadata(uint index) const
  {
    DBUG_ASSERT(index < m_size);
    if (m_field_metadata_size)
      return m_field_metadata[index];
    else
      return 0;
  }

  /*
    This function returns whether the field on the master can be null.
    This value is derived from field->maybe_null().
  */
  inline my_bool maybe_null(uint index) const
  {
    DBUG_ASSERT(index < m_size);
    return (m_null_bits[(index / 8)] & (1 << (index % 8))) != 0;
  }

  /*
    This function returns the field size in raw bytes based on the type
    and the encoded field data from the master's raw data. This method can 
    be used for situations where the slave needs to skip a column (e.g., 
    WL#3915) or needs to advance the pointer for the fields in the raw 
    data from the master to a specific column.
  */
  uint32 calc_field_size(uint col, uchar *master_data) const;

  /**
     Compare the master table with an existing table on the slave and
     create a conversion map for fields that needs to be converted and
     update master_to_slave_error[] map with fields that does not
     exist on the slave or are not compatible with the field with the
     same name on the slave.

     If any fields need to be converted, a temporary conversion table
     is created with the fields that needs conversions

     @param thd
     @param rgi   Pointer to relay log info
     @param table Pointer to table to compare with.

     @return 0 ok
     @return 1 Something went wrong (OOM?)
  */
#ifndef MYSQL_CLIENT
  bool compatible_with(THD *thd, rpl_group_info *rgi,
                       RPL_TABLE_LIST *table) const;

  /**
   Create a virtual in-memory temporary table structure.

   @param thd Thread to allocate memory from.
   @param rli Relay log info structure, for error reporting.
   @param target_table Target table for fields.

   @return A pointer to a temporary table with memory allocated in the
           thread's memroot, NULL if the table could not be created

   The table structure has records and field array so that a row can
   be unpacked into the record for further processing.

   In the virtual table, each field that requires conversion will
   have a non-NULL value, while fields that do not require
   conversion will have a NULL value.

   Some information that is missing in the events, such as the
   character set for string types, are taken from the table that the
   field is going to be pushed into, so the target table that the data
   eventually need to be pushed into need to be supplied.

   Note that the fields generated in the conversion table are not guaranteed to
   align with the fields from this table_def. If the slave doesn't have the
   target field, we don't generate a field in the conversion_table, as it would
   serve no purpose. If the conversion table is referenced while iterating
   through this table_def, one needs a separate index to keep track of the
   conv_table fields, which are only incremented when the slave has that
   column. This can be checked using member variable master_to_slave_error:
   when an element in that array is 0, it means that field exists on the slave.
   See other member function of table_def compatible_with() for an example of
   this.
   */
  TABLE *create_conversion_table(THD *thd, rpl_group_info *rgi,
                                 RPL_TABLE_LIST *target_table) const;
#endif

private:
  unsigned char *m_type;  // Array of type descriptors
  uint m_size;           // Number of elements in the types array
  uint m_field_metadata_size;
  uint16 *m_field_metadata;
  uint16 m_flags;         // Table flags
  uchar *m_null_bits;
  uchar *m_memory;
public:
  LEX_CUSTRING optional_metadata;
  uint *master_to_slave_map;
  uint *master_to_slave_error;
  char **master_column_name;
};

/* Different errors when converting a field from master to slave */

#define SLAVE_FIELD_NAME_MISSING  1
#define SLAVE_FIELD_NR_MISSING    2
#define SLAVE_FIELD_UNKNOWN_TYPE  3
#define SLAVE_FIELD_WRONG_TYPE    4

#ifndef MYSQL_CLIENT
/**
   Extend the normal table list with a few new fields needed by the
   slave thread, but nowhere else.
 */
struct RPL_TABLE_LIST : public TABLE_LIST
{
  table_def m_tabledef;
  TABLE *m_conv_table;
  const Copy_field *m_online_alter_copy_fields;
  const Copy_field *m_online_alter_copy_fields_end;
  uint cached_key_nr;                  // [0..MAX_KEY] if set, ~0U if unset
  uint cached_usable_key_parts;
  bool m_tabledef_valid;
  bool master_had_triggers;
  LEX_CUSTRING optional_metadata;

  RPL_TABLE_LIST(const LEX_CSTRING *db_arg, const LEX_CSTRING *table_name_arg,
                 thr_lock_type thr_lock_type,
                 table_def &&tabledef, bool master_had_trigers)
    : TABLE_LIST(db_arg, table_name_arg, NULL, thr_lock_type),
      m_tabledef(std::move(tabledef)), m_conv_table(NULL),
      m_online_alter_copy_fields(NULL), m_online_alter_copy_fields_end(NULL),
      cached_key_nr(~0U), m_tabledef_valid(true),
      master_had_triggers(master_had_trigers)
  {
    optional_metadata.length= 0;
  }

  RPL_TABLE_LIST(TABLE *table, thr_lock_type lock_type, TABLE *conv_table,
                 table_def &&tabledef,
                 const Copy_field online_alter_copy_fields[],
                 const Copy_field *online_alter_copy_fields_end)
    : TABLE_LIST(table, lock_type),
      m_tabledef(std::move(tabledef)), m_conv_table(conv_table),
      m_online_alter_copy_fields(online_alter_copy_fields),
      m_online_alter_copy_fields_end(online_alter_copy_fields_end),
      cached_key_nr(~0U), m_tabledef_valid(true), master_had_triggers(false)
  {
    optional_metadata.length= 0;
  }
  bool create_column_mapping(rpl_group_info *rgi);
  bool give_compatibility_error(rpl_group_info *rgi, uint col);
  bool check_wrong_column_usage(rpl_group_info *rgi, MY_BITMAP *m_cols);
};


/* Anonymous namespace for template functions/classes */
CPP_UNNAMED_NS_START

  /*
    Smart pointer that will automatically call my_afree (a macro) when
    the pointer goes out of scope.  This is used so that I do not have
    to remember to call my_afree() before each return.  There is no
    overhead associated with this, since all functions are inline.

    I (Matz) would prefer to use the free function as a template
    parameter, but that is not possible when the "function" is a
    macro.
  */
  template <class Obj>
  class auto_afree_ptr
  {
    Obj* m_ptr;
  public:
    auto_afree_ptr(Obj* ptr) : m_ptr(ptr) { }
    ~auto_afree_ptr() { if (m_ptr) my_afree(m_ptr); }
    void assign(Obj* ptr) {
      /* Only to be called if it hasn't been given a value before. */
      DBUG_ASSERT(m_ptr == NULL);
      m_ptr= ptr;
    }
    Obj* get() { return m_ptr; }
  };

CPP_UNNAMED_NS_END

class Deferred_log_events
{
private:
  DYNAMIC_ARRAY array;
  Log_event *last_added;

public:
  Deferred_log_events(Relay_log_info *rli);
  ~Deferred_log_events();
  /* queue for exection at Query-log-event time prior the Query */
  int add(Log_event *ev);
  bool is_empty();
  bool execute(struct rpl_group_info *rgi);
  void rewind();
  bool is_last(Log_event *ev) { return ev == last_added; };
};

#endif

// NB. number of printed bit values is limited to sizeof(buf) - 1
#define DBUG_PRINT_BITSET(N,FRM,BS)                \
  do {                                             \
    char buf[256];                                 \
    uint i;                                        \
    for (i = 0 ; i < MY_MIN(sizeof(buf) - 1, (BS)->n_bits) ; i++) \
      buf[i] = bitmap_is_set((BS), i) ? '1' : '0'; \
    buf[i] = '\0';                                 \
    DBUG_PRINT((N), ((FRM), buf));                 \
  } while (0)

#endif /* RPL_UTILITY_H */