@ -452,8 +452,10 @@ public:
class Server_side_cursor ;
/*
State of a single command executed against this connection .
/**
@ class Statement
@ brief State of a single command executed against this connection .
One connection can contain a lot of simultaneously running statements ,
some of which could be :
- prepared , that is , contain placeholders ,
@ -471,10 +473,6 @@ class Statement: public ilink, public Query_arena
Statement ( const Statement & rhs ) ; /* not implemented: */
Statement & operator = ( const Statement & rhs ) ; /* non-copyable */
public :
/* FIXME: these must be protected */
MEM_ROOT main_mem_root ;
LEX main_lex ;
/*
Uniquely identifies each statement object in thread scope ; change during
statement lifetime . FIXME : must be const
@ -525,10 +523,10 @@ public:
public :
/* This constructor is called for backup statements */
Statement ( ) { clear_alloc_root ( & main_mem_root ) ; }
Statement ( ) { }
Statement ( enum enum_state state_arg , ulong id _arg,
ulong alloc_block_size , ulong prealloc_size ) ;
Statement ( LEX * lex_arg , MEM_ROOT * mem_root _arg,
enum enum_state state_arg , ulong id_arg ) ;
virtual ~ Statement ( ) ;
/* Assign execution context (note: not all members) of given stmt to self */
@ -540,7 +538,7 @@ public:
} ;
/*
/**
Container for all statements created / used in a connection .
Statements in Statement_map have unique Statement : : id ( guaranteed by id
assignment in Statement : : Statement )
@ -620,6 +618,10 @@ bool xid_cache_insert(XID *xid, enum xa_states xa_state);
bool xid_cache_insert ( XID_STATE * xid_state ) ;
void xid_cache_delete ( XID_STATE * xid_state ) ;
/**
@ class Security_context
@ brief A set of THD members describing the current authenticated user .
*/
class Security_context {
public :
@ -651,7 +653,7 @@ public:
} ;
/*
/**
A registry for item tree transformations performed during
query optimization . We register only those changes which require
a rollback to re - execute a prepared statement or stored procedure
@ -662,7 +664,7 @@ struct Item_change_record;
typedef I_List < Item_change_record > Item_change_list ;
/*
/**
Type of prelocked mode .
See comment for THD : : prelocked_mode for complete description .
*/
@ -671,7 +673,7 @@ enum prelocked_mode_type {NON_PRELOCKED= 0, PRELOCKED= 1,
PRELOCKED_UNDER_LOCK_TABLES = 2 } ;
/*
/**
Class that holds information about tables which were opened and locked
by the thread . It is also used to save / restore this information in
push_open_tables_state ( ) / pop_open_tables_state ( ) .
@ -774,14 +776,17 @@ public:
}
} ;
/* class to save context when executing a function or trigger */
/**
@ class Sub_statement_state
@ brief Used to save context when executing a function or trigger
*/
/* Defines used for Sub_statement_state::in_sub_stmt */
# define SUB_STMT_TRIGGER 1
# define SUB_STMT_FUNCTION 2
class Sub_statement_state
{
public :
@ -856,7 +861,8 @@ public:
} ;
/*
/**
@ class THD
For each client connection we create a separate thread with THD serving as
a thread / connection descriptor
*/
@ -1700,6 +1706,22 @@ public:
private :
/** The current internal error handler for this thread, or NULL. */
Internal_error_handler * m_internal_handler ;
/**
The lex to hold the parsed tree of conventional ( non - prepared ) queries .
Whereas for prepared and stored procedure statements we use an own lex
instance for each new query , for conventional statements we reuse
the same lex . ( @ see mysql_parse for details ) .
*/
LEX main_lex ;
/**
This memory root is used for two purposes :
- for conventional queries , to allocate structures stored in main_lex
during parsing , and allocate runtime data ( execution plan , etc . )
during execution .
- for prepared queries , only to allocate runtime data . The parsed
tree itself is reused between executions and thus is stored elsewhere .
*/
MEM_ROOT main_mem_root ;
} ;
unknown
19 years ago