~drizzle-trunk/drizzle/development

/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-

 *  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

 *

 *  Copyright (C) 2008 Sun Microsystems

 *

 *  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  02110-1301  USA

 */

#ifndef DRIZZLED_SESSION_H

#define DRIZZLED_SESSION_H

/* Classes in mysql */

#include <drizzled/plugin/protocol.h>

#include <drizzled/sql_locale.h>

#include <drizzled/ha_trx_info.h>

#include <mysys/my_alloc.h>

#include <mysys/my_tree.h>

#include <drizzled/handler.h>

#include <drizzled/current_session.h>

#include <drizzled/sql_error.h>

#include <drizzled/file_exchange.h>

#include <drizzled/select_result_interceptor.h>

#include <drizzled/authentication.h>

#include <drizzled/db.h>

#include <drizzled/xid.h>

#include <netdb.h>

#include <string>

#include <bitset>

#define MIN_HANDSHAKE_SIZE      6

class Lex_input_stream;

class user_var_entry;

class CopyField;

class Table_ident;

extern char internal_table_name[2];

extern char empty_c_string[1];

extern const char **errmesg;

#define TC_HEURISTIC_RECOVER_COMMIT   1

#define TC_HEURISTIC_RECOVER_ROLLBACK 2

extern uint32_t tc_heuristic_recover;

/**

  The COPY_INFO structure is used by INSERT/REPLACE code.

  The schema of the row counting by the INSERT/INSERT ... ON DUPLICATE KEY

  UPDATE code:

    If a row is inserted then the copied variable is incremented.

    If a row is updated by the INSERT ... ON DUPLICATE KEY UPDATE and the

      new data differs from the old one then the copied and the updated

      variables are incremented.

    The touched variable is incremented if a row was touched by the update part

      of the INSERT ... ON DUPLICATE KEY UPDATE no matter whether the row

      was actually changed or not.

*/

typedef struct st_copy_info 

{

  ha_rows records; /**< Number of processed records */

  ha_rows deleted; /**< Number of deleted records */

  ha_rows updated; /**< Number of updated records */

  ha_rows copied;  /**< Number of copied records */

  ha_rows error_count;

  ha_rows touched; /* Number of touched records */

  enum enum_duplicates handle_duplicates;

  int escape_char, last_errno;

  bool ignore;

  /* for INSERT ... UPDATE */

  List<Item> *update_fields;

  List<Item> *update_values;

  /* for VIEW ... WITH CHECK OPTION */

} COPY_INFO;

typedef struct drizzled_lock_st

{

  Table **table;

  uint32_t table_count;

  uint32_t lock_count;

  THR_LOCK_DATA **locks;

} DRIZZLE_LOCK;

#include <drizzled/lex_column.h>

class select_result;

class Time_zone;

#define Session_SENTRY_MAGIC 0xfeedd1ff

#define Session_SENTRY_GONE  0xdeadbeef

#define Session_CHECK_SENTRY(session) assert(session->dbug_sentry == Session_SENTRY_MAGIC)

struct system_variables

{

  system_variables() {};

  /*

    How dynamically allocated system variables are handled:

    The global_system_variables and max_system_variables are "authoritative"

    They both should have the same 'version' and 'size'.

    When attempting to access a dynamic variable, if the session version

    is out of date, then the session version is updated and realloced if

    neccessary and bytes copied from global to make up for missing data.

  */

  ulong dynamic_variables_version;

  char * dynamic_variables_ptr;

  uint32_t dynamic_variables_head;  /* largest valid variable offset */

  uint32_t dynamic_variables_size;  /* how many bytes are in use */

  uint64_t myisam_max_extra_sort_file_size;

  uint64_t max_heap_table_size;

  uint64_t tmp_table_size;

  ha_rows select_limit;

  ha_rows max_join_size;

  uint64_t auto_increment_increment;

  uint64_t auto_increment_offset;

  uint64_t bulk_insert_buff_size;

  uint64_t join_buff_size;

  uint32_t max_allowed_packet;

  uint32_t myisam_stats_method;

  uint64_t max_error_count;

  uint64_t max_length_for_sort_data;

  size_t max_sort_length;

  uint64_t min_examined_row_limit;

  uint32_t net_buffer_length;

  uint32_t net_read_timeout;

  uint32_t net_retry_count;

  uint32_t net_wait_timeout;

  uint32_t net_write_timeout;

  bool optimizer_prune_level;

  bool log_warnings;

  bool engine_condition_pushdown;

  uint32_t optimizer_search_depth;

  /*

    Controls use of Engine-MRR:

      0 - auto, based on cost

      1 - force MRR when the storage engine is capable of doing it

      2 - disable MRR.

  */

  uint32_t optimizer_use_mrr;

  /* A bitmap for switching optimizations on/off */

  uint32_t optimizer_switch;

  uint32_t div_precincrement;

  uint64_t preload_buff_size;

  uint32_t read_buff_size;

  uint32_t read_rnd_buff_size;

  size_t sortbuff_size;

  uint32_t thread_handling;

  uint32_t tx_isolation;

  uint32_t completion_type;

  /* Determines which non-standard SQL behaviour should be enabled */

  uint32_t sql_mode;

  uint64_t max_seeks_for_key;

  size_t range_alloc_block_size;

  uint32_t query_alloc_block_size;

  uint32_t query_prealloc_size;

  uint32_t trans_alloc_block_size;

  uint32_t trans_prealloc_size;

  uint64_t group_concat_max_len;

  /* TODO: change this to my_thread_id - but have to fix set_var first */

  uint64_t pseudo_thread_id;

  StorageEngine *storage_engine;

  /* Only charset part of these variables is sensible */

  const CHARSET_INFO  *character_set_filesystem;

  /* Both charset and collation parts of these variables are important */

  const CHARSET_INFO	*collation_server;

  inline const CHARSET_INFO  *getCollation(void) 

  {

    return collation_server;

  }

  /* Locale Support */

  MY_LOCALE *lc_time_names;

  Time_zone *time_zone;

};

extern struct system_variables global_system_variables;

#include "sql_lex.h"

/**

 * Per-session local status counters

 */

typedef struct system_status_var

{

  uint64_t bytes_received;

  uint64_t bytes_sent;

  ulong com_other;

  ulong com_stat[(uint32_t) SQLCOM_END];

  ulong created_tmp_disk_tables;

  ulong created_tmp_tables;

  ulong ha_commit_count;

  ulong ha_delete_count;

  ulong ha_read_first_count;

  ulong ha_read_last_count;

  ulong ha_read_key_count;

  ulong ha_read_next_count;

  ulong ha_read_prev_count;

  ulong ha_read_rnd_count;

  ulong ha_read_rnd_next_count;

  ulong ha_rollback_count;

  ulong ha_update_count;

  ulong ha_write_count;

  ulong ha_prepare_count;

  ulong ha_savepoint_count;

  ulong ha_savepoint_rollback_count;

  /* KEY_CACHE parts. These are copies of the original */

  ulong key_blocks_changed;

  ulong key_blocks_used;

  ulong key_cache_r_requests;

  ulong key_cache_read;

  ulong key_cache_w_requests;

  ulong key_cache_write;

  /* END OF KEY_CACHE parts */

  ulong net_big_packet_count;

  ulong opened_tables;

  ulong opened_shares;

  ulong select_full_join_count;

  ulong select_full_range_join_count;

  ulong select_range_count;

  ulong select_range_check_count;

  ulong select_scan_count;

  ulong long_query_count;

  ulong filesort_merge_passes;

  ulong filesort_range_count;

  ulong filesort_rows;

  ulong filesort_scan_count;

  /*

    Number of statements sent from the client

  */

  ulong questions;

  /*

    IMPORTANT!

    SEE last_system_status_var DEFINITION BELOW.

    Below 'last_system_status_var' are all variables which doesn't make any

    sense to add to the /global/ status variable counter.

  */

  double last_query_cost;

} STATUS_VAR;

/*

  This is used for 'SHOW STATUS'. It must be updated to the last ulong

  variable in system_status_var which is makes sens to add to the global

  counter

*/

#define last_system_status_var questions

void mark_transaction_to_rollback(Session *session, bool all);

/**

 * Single command executed against this connection.

 *

 * @details

 *

 * One connection can contain a lot of simultaneously running statements,

 * some of which could be prepared, that is, contain placeholders.

 *

 * To perform some action with statement we reset Session part to the state  of

 * that statement, do the action, and then save back modified state from Session

 * to the statement. It will be changed in near future, and Statement will

 * be used explicitly.

 *

 * @todo

 *

 * The above comment is bullshit in Drizzle. See TODO markers on Session to

 * completely detach the inheritance of Session from Statement.

 */

class Statement

{

  Statement(const Statement &rhs);              /* not implemented: */

  Statement &operator=(const Statement &rhs);   /* non-copyable */

public:

  /**

   * List of items created in the parser for this query. Every item puts

   * itself to the list on creation (see Item::Item() for details))

   */

  Item *free_list;

  MEM_ROOT *mem_root; /**< Pointer to current memroot */

  /**

   * Uniquely identifies each statement object in thread scope; change during

   * statement lifetime.

   *

   * @todo should be const

   */

   uint32_t id;

  /*

    MARK_COLUMNS_NONE:  Means mark_used_colums is not set and no indicator to

                        handler of fields used is set

    MARK_COLUMNS_READ:  Means a bit in read set is set to inform handler

	                that the field is to be read. If field list contains

                        duplicates, then session->dup_field is set to point

                        to the last found duplicate.

    MARK_COLUMNS_WRITE: Means a bit is set in write set to inform handler

			that it needs to update this field in write_row

                        and update_row.

  */

  enum enum_mark_columns mark_used_columns;

  LEX *lex; /**< parse tree descriptor */

  /**

    Points to the query associated with this statement. It's const, but

    we need to declare it char * because all table handlers are written

    in C and need to point to it.

    Note that (A) if we set query = NULL, we must at the same time set

    query_length = 0, and protect the whole operation with the

    LOCK_thread_count mutex. And (B) we are ONLY allowed to set query to a

    non-NULL value if its previous value is NULL. We do not need to protect

    operation (B) with any mutex. To avoid crashes in races, if we do not

    know that session->query cannot change at the moment, one should print

    session->query like this:

      (1) reserve the LOCK_thread_count mutex;

      (2) check if session->query is NULL;

      (3) if not NULL, then print at most session->query_length characters from

      it. We will see the query_length field as either 0, or the right value

      for it.

    Assuming that the write and read of an n-bit memory field in an n-bit

    computer is atomic, we can avoid races in the above way.

    This printing is needed at least in SHOW PROCESSLIST and SHOW INNODB

    STATUS.

  */

  char *query;

  uint32_t query_length; /**< current query length */

  /**

    Name of the current (default) database.

    If there is the current (default) database, "db" contains its name. If

    there is no current (default) database, "db" is NULL and "db_length" is

    0. In other words, "db", "db_length" must either be NULL, or contain a

    valid database name.

    @note this attribute is set and alloced by the slave SQL thread (for

    the Session of that thread); that thread is (and must remain, for now) the

    only responsible for freeing this member.

  */

  char *db;

  uint32_t db_length; /**< Length of current schema name */

public:

  /* This constructor is called for backup statements */

  Statement() {}

  Statement(LEX *lex_arg, MEM_ROOT *mem_root_arg, uint32_t id_arg)

  :

    free_list(NULL), 

    mem_root(mem_root_arg),

    id(id_arg),

    mark_used_columns(MARK_COLUMNS_READ),

    lex(lex_arg),

    query(NULL),

    query_length(0),

    db(NULL),

    db_length(0)

  {}

  virtual ~Statement() {}

  inline void* alloc(size_t size)

  {

    return alloc_root(mem_root,size);

  }

  inline void* calloc(size_t size)

  {

    void *ptr;

    if ((ptr= alloc_root(mem_root,size)))

      memset(ptr, 0, size);

    return ptr;

  }

  inline char *strdup(const char *str)

  {

    return strdup_root(mem_root,str);

  }

  inline char *strmake(const char *str, size_t size)

  {

    return strmake_root(mem_root,str,size);

  }

  inline void *memdup(const void *str, size_t size)

  {

    return memdup_root(mem_root,str,size);

  }

  inline void *memdup_w_gap(const void *str, size_t size, uint32_t gap)

  {

    void *ptr;

    if ((ptr= alloc_root(mem_root,size+gap)))

      memcpy(ptr,str,size);

    return ptr;

  }

  /** Frees all items attached to this Statement */

  void free_items();

};

struct st_savepoint 

{

  struct st_savepoint *prev;

  char *name;

  uint32_t length;

  Ha_trx_info *ha_list;

};

extern pthread_mutex_t LOCK_xid_cache;

extern HASH xid_cache;

#include <drizzled/security_context.h>

#include <drizzled/open_tables_state.h>

#include <drizzled/internal_error_handler.h> 

#include <drizzled/diagnostics_area.h> 

/**

  Storage engine specific thread local data.

*/

struct Ha_data

{

  /**

    Storage engine specific thread local data.

    Lifetime: one user connection.

  */

  void *ha_ptr;

  /**

    0: Life time: one statement within a transaction. If @@autocommit is

    on, also represents the entire transaction.

    @sa trans_register_ha()

    1: Life time: one transaction within a connection.

    If the storage engine does not participate in a transaction,

    this should not be used.

    @sa trans_register_ha()

  */

  Ha_trx_info ha_info[2];

  Ha_data() :ha_ptr(NULL) {}

};

/**

 * Represents a client connection to the database server.

 *

 * Contains the client/server protocol object, the current statement

 * being executed, local-to-session variables and status counters, and

 * a host of other information.

 *

 * @todo

 *

 * Session should NOT inherit from Statement, but rather it should have a

 * vector of Statement object pointers which comprise the statements executed

 * on the Session.  Until this architectural change is done, we can forget

 * about parallel operations inside a session.

 *

 * @todo

 *

 * Make member variables private and have inlined accessors and setters.  Hide

 * all member variables that are not critical to non-internal operations of the

 * session object.

 */

class Session :public Statement, public Open_tables_state

{

public:

  /**

    Constant for Session::where initialization in the beginning of every query.

    It's needed because we do not save/restore Session::where normally during

    primary (non subselect) query execution.

  */

  static const char * const DEFAULT_WHERE;

  MEM_ROOT warn_root; /**< Allocation area for warnings and errors */

  Protocol *protocol;	/**< Pointer to the current protocol */

  HASH user_vars; /**< Hash of user variables defined during the session's lifetime */

  String packet; /**< dynamic buffer for network I/O */

  String convert_buffer; /**< A buffer for charset conversions */

  struct system_variables variables; /**< Mutable local variables local to the session */

  struct system_status_var status_var; /**< Session-local status counters */

  struct system_status_var *initial_status_var; /* used by show status */

  THR_LOCK_INFO lock_info; /**< Locking information for this session */

  THR_LOCK_OWNER main_lock_id; /**< To use for conventional queries */

  THR_LOCK_OWNER *lock_id; /**< If not main_lock_id, points to the lock_id of a cursor. */

  pthread_mutex_t LOCK_delete; /**< Locked before session is deleted */

  /**

   * A peek into the query string for the session. This is a best effort

   * delivery, there is no guarantee whether the content is meaningful.

   */

  char process_list_info[PROCESS_LIST_WIDTH+1];

  /**

   * A pointer to the stack frame of handle_one_connection(),

   * which is called first in the thread for handling a client

   */

  char *thread_stack;

  /**

    @note

    Some members of Session (currently 'Statement::db',

    'query')  are set and alloced by the slave SQL thread

    (for the Session of that thread); that thread is (and must remain, for now)

    the only responsible for freeing these 3 members. If you add members

    here, and you add code to set them in replication, don't forget to

    free_them_and_set_them_to_0 in replication properly. For details see

    the 'err:' label of the handle_slave_sql() in sql/slave.cc.

    @see handle_slave_sql

  */

  Security_context security_ctx;

  /**

    Used in error messages to tell user in what part of MySQL we found an

    error. E. g. when where= "having clause", if fix_fields() fails, user

    will know that the error was in having clause.

  */

  const char *where;

  /*

    One thread can hold up to one named user-level lock. This variable

    points to a lock object if the lock is present. See item_func.cc and

    chapter 'Miscellaneous functions', for functions GET_LOCK, RELEASE_LOCK.

  */

  uint32_t dbug_sentry; /**< watch for memory corruption */

  struct st_my_thread_var *mysys_var;

  /**

   * Type of current query: COM_STMT_PREPARE, COM_QUERY, etc. Set from

   * first byte of the packet in executeStatement()

   */

  enum enum_server_command command;

  uint32_t file_id;	/**< File ID for LOAD DATA INFILE */

  /* @note the following three members should likely move to Protocol */

  uint32_t client_capabilities; /**< What the client supports */

  uint16_t peer_port; /**< The remote (peer) port */

  uint32_t max_client_packet_length; /**< Maximum number of bytes a client can send in a single packet */

  time_t start_time;

  time_t user_time;

  uint64_t connect_utime;

  uint64_t thr_create_utime; /**< track down slow pthread_create */

  uint64_t start_utime;

  uint64_t utime_after_lock;

  thr_lock_type update_lock_default;

  /*

    Both of the following container points in session will be converted to an API.

  */

  /* container for handler's private per-connection data */

  Ha_data ha_data[MAX_HA];

  /* container for replication data */

  void *replication_data;

  struct st_transactions {

    SAVEPOINT *savepoints;

    Session_TRANS all;			// Trans since BEGIN WORK

    Session_TRANS stmt;			// Trans for current statement

    bool on;                            // see ha_enable_transaction()

    XID_STATE xid_state;

    /*

       Tables changed in transaction (that must be invalidated in query cache).

       List contain only transactional tables, that not invalidated in query

       cache (instead of full list of changed in transaction tables).

    */

    CHANGED_TableList* changed_tables;

    MEM_ROOT mem_root; // Transaction-life memory allocation pool

    void cleanup()

    {

      changed_tables= 0;

      savepoints= 0;

      free_root(&mem_root,MYF(MY_KEEP_PREALLOC));

    }

    st_transactions()

    {

      memset(this, 0, sizeof(*this));

      xid_state.xid.null();

      init_sql_alloc(&mem_root, ALLOC_ROOT_MIN_BLOCK_SIZE, 0);

    }

  } transaction;

  Field *dup_field;

  sigset_t signals;

  /* Tells if LAST_INSERT_ID(#) was called for the current statement */

  bool arg_of_last_insert_id_function;

  /*

    ALL OVER THIS FILE, "insert_id" means "*automatically generated* value for

    insertion into an auto_increment column".

  */

  /**

    This is the first autogenerated insert id which was *successfully*

    inserted by the previous statement (exactly, if the previous statement

    didn't successfully insert an autogenerated insert id, then it's the one

    of the statement before, etc).

    It can also be set by SET LAST_INSERT_ID=# or SELECT LAST_INSERT_ID(#).

    It is returned by LAST_INSERT_ID().

  */

  uint64_t first_successful_insert_id_in_prev_stmt;

  /**

    This is the first autogenerated insert id which was *successfully*

    inserted by the current statement. It is maintained only to set

    first_successful_insert_id_in_prev_stmt when statement ends.

  */

  uint64_t first_successful_insert_id_in_cur_stmt;

  /**

    We follow this logic:

    - when stmt starts, first_successful_insert_id_in_prev_stmt contains the

    first insert id successfully inserted by the previous stmt.

    - as stmt makes progress, handler::insert_id_for_cur_row changes;

    every time get_auto_increment() is called,

    auto_inc_intervals_in_cur_stmt_for_binlog is augmented with the

    reserved interval (if statement-based binlogging).

    - at first successful insertion of an autogenerated value,

    first_successful_insert_id_in_cur_stmt is set to

    handler::insert_id_for_cur_row.

    - when stmt goes to binlog,

    auto_inc_intervals_in_cur_stmt_for_binlog is binlogged if

    non-empty.

    - when stmt ends, first_successful_insert_id_in_prev_stmt is set to

    first_successful_insert_id_in_cur_stmt.

    List of auto_increment intervals reserved by the thread so far, for

    storage in the statement-based binlog.

    Note that its minimum is not first_successful_insert_id_in_cur_stmt:

    assuming a table with an autoinc column, and this happens:

    INSERT INTO ... VALUES(3);

    SET INSERT_ID=3; INSERT IGNORE ... VALUES (NULL);

    then the latter INSERT will insert no rows

    (first_successful_insert_id_in_cur_stmt == 0), but storing "INSERT_ID=3"

    in the binlog is still needed; the list's minimum will contain 3.

  */

  Discrete_intervals_list auto_inc_intervals_in_cur_stmt_for_binlog;

  /** Used by replication and SET INSERT_ID */

  Discrete_intervals_list auto_inc_intervals_forced;

  uint64_t limit_found_rows;

  uint64_t options; /**< Bitmap of options */

  int64_t row_count_func; /**< For the ROW_COUNT() function */

  ha_rows cuted_fields; /**< Count of "cut" or truncated fields. @todo Kill this friggin thing. */

  /** 

   * Number of rows we actually sent to the client, including "synthetic"

   * rows in ROLLUP etc.

   */

  ha_rows sent_row_count;

  /**

   * Number of rows we read, sent or not, including in create_sort_index()

   */

  ha_rows examined_row_count;

  /**

   * The set of those tables whose fields are referenced in all subqueries

   * of the query.

   *

   * @todo

   * 

   * Possibly this it is incorrect to have used tables in Session because

   * with more than one subquery, it is not clear what does the field mean.

   */

  table_map used_tables;

  /**

    @todo

    This, and some other variables like 'count_cuted_fields'

    maybe should be statement/cursor local, that is, moved to Statement

    class. With current implementation warnings produced in each prepared

    statement/cursor settle here.

  */

  List<DRIZZLE_ERROR> warn_list;

  uint32_t warn_count[(uint32_t) DRIZZLE_ERROR::WARN_LEVEL_END];

  uint32_t total_warn_count;

  Diagnostics_area main_da;

  /*

    Id of current query. Statement can be reused to execute several queries

    query_id is global in context of the whole MySQL server.

    ID is automatically generated from mutex-protected counter.

    It's used in handler code for various purposes: to check which columns

    from table are necessary for this select, to check if it's necessary to

    update auto-updatable fields (like auto_increment and timestamp).

  */

  query_id_t query_id;

  query_id_t warn_id;

  ulong col_access;

#ifdef ERROR_INJECT_SUPPORT

  ulong error_inject_value;

#endif

  /* Statement id is thread-wide. This counter is used to generate ids */

  uint32_t statement_id_counter;

  uint32_t rand_saved_seed1;

  uint32_t rand_saved_seed2;

  /**

    Row counter, mainly for errors and warnings. Not increased in

    create_sort_index(); may differ from examined_row_count.

  */

  uint32_t row_count;

  pthread_t real_id; /**< For debugging */

  my_thread_id thread_id;

  uint32_t tmp_table;

  uint32_t global_read_lock;

  uint32_t server_status;

  uint32_t open_options;

  uint32_t select_number; /**< number of select (used for EXPLAIN) */

  /* variables.transaction_isolation is reset to this after each commit */

  enum_tx_isolation session_tx_isolation;

  enum_check_fields count_cuted_fields;

  enum killed_state

  {

    NOT_KILLED,

    KILL_BAD_DATA,

    KILL_CONNECTION,

    KILL_QUERY,

    KILLED_NO_VALUE /* means none of the above states apply */

  };

  killed_state volatile killed;

  bool some_tables_deleted;

  bool no_errors;

  bool password;

  /**

    Set to true if execution of the current compound statement

    can not continue. In particular, disables activation of

    CONTINUE or EXIT handlers of stored routines.

    Reset in the end of processing of the current user request, in

    @see mysql_reset_session_for_next_command().

  */

  bool is_fatal_error;

  /**

    Set by a storage engine to request the entire

    transaction (that possibly spans multiple engines) to

    rollback. Reset in ha_rollback.

  */

  bool transaction_rollback_request;

  /**

    true if we are in a sub-statement and the current error can

    not be safely recovered until we left the sub-statement mode.

    In particular, disables activation of CONTINUE and EXIT

    handlers inside sub-statements. E.g. if it is a deadlock

    error and requires a transaction-wide rollback, this flag is

    raised (traditionally, MySQL first has to close all the reads

    via @see handler::ha_index_or_rnd_end() and only then perform

    the rollback).

    Reset to false when we leave the sub-statement mode.

  */

  bool is_fatal_sub_stmt_error;

  /** for IS NULL => = last_insert_id() fix in remove_eq_conds() */

  bool substitute_null_with_insert_id;

  bool cleanup_done;

  bool abort_on_warning;

  bool got_warning; /**< Set on call to push_warning() */

  bool no_warnings_for_error; /**< no warnings on call to my_error() */

  /** set during loop of derived table processing */

  bool derived_tables_processing;

  bool tablespace_op; /**< This is true in DISCARD/IMPORT TABLESPACE */

  /** Used by the sys_var class to store temporary values */

  union

  {

    bool bool_value;

    uint32_t uint32_t_value;

    int32_t int32_t_value;

    uint64_t uint64_t_value;

  } sys_var_tmp;

  /**

    Character input stream consumed by the lexical analyser,

    used during parsing.

    Note that since the parser is not re-entrant, we keep only one input

    stream here. This member is valid only when executing code during parsing,

    and may point to invalid memory after that.

  */

  Lex_input_stream *m_lip;

  /** session_scheduler for events */

  void *scheduler;

  /** Place to store various things */

  void *session_marker;

  /** Keeps a copy of the previous table around in case we are just slamming on particular table */

  Table *cached_table;

  /**

    Points to info-string that we show in SHOW PROCESSLIST

    You are supposed to call Session_SET_PROC_INFO only if you have coded

    a time-consuming piece that MySQL can get stuck in for a long time.

    Set it using the  session_proc_info(Session *thread, const char *message)

    macro/function.

  */

  inline void set_proc_info(const char *info)

  { 

    proc_info= info;

  }

  inline const char* get_proc_info() const

  {

    return proc_info;

  }

  inline void setReplicationData (void *data)

  {

    replication_data= data;

  }

  inline void *getReplicationData () const

  {

    return replication_data;

  }

  /** Returns the current query ID */

  inline query_id_t getQueryId()  const

  {

    return query_id;

  }

  /** Returns the current query text */

  inline const char *getQueryString()  const

  {

    return query;