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A review comment for the fix for Bug#46672.

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Remove unnecessary need_reopen loops.
This commit is contained in:
Konstantin Osipov
2010-03-13 13:58:27 +03:00
parent 42b7812898
commit 9cb8a98216
14 changed files with 231 additions and 371 deletions
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60
sql/sql_handler.cc
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@ -405,6 +405,56 @@ bool mysql_ha_close(THD *thd, TABLE_LIST *tables)
}
/**
A helper class to process an error from mysql_lock_tables().
HANDLER READ statement's attempt to lock the subject table
may get aborted if there is a pending DDL. In that case
we close the table, reopen it, and try to read again.
This is implicit and obscure, since HANDLER position
is lost in the process, but it's the legacy server
behaviour we should preserve.
*/
class Sql_handler_lock_error_handler: public Internal_error_handler
{
public:
virtual
bool handle_condition(THD *thd,
uint sql_errno,
const char *sqlstate,
MYSQL_ERROR::enum_warning_level level,
const char* msg,
MYSQL_ERROR **cond_hdl);
bool need_reopen() const { return m_need_reopen; };
void init() { m_need_reopen= FALSE; };
private:
bool m_need_reopen;
};
/**
Handle an error from mysql_lock_tables().
Ignore ER_LOCK_ABORTED errors.
*/
bool
Sql_handler_lock_error_handler::
handle_condition(THD *thd,
uint sql_errno,
const char *sqlstate,
MYSQL_ERROR::enum_warning_level level,
const char* msg,
MYSQL_ERROR **cond_hdl)
{
*cond_hdl= NULL;
if (sql_errno == ER_LOCK_ABORTED)
m_need_reopen= TRUE;
return m_need_reopen;
}
/*
Read from a HANDLER table.
@ -442,7 +492,7 @@ bool mysql_ha_read(THD *thd, TABLE_LIST *tables,
uint num_rows;
uchar *UNINIT_VAR(key);
uint UNINIT_VAR(key_len);
bool need_reopen;
Sql_handler_lock_error_handler sql_handler_lock_error;
DBUG_ENTER("mysql_ha_read");
DBUG_PRINT("enter",("'%s'.'%s' as '%s'",
tables->db, tables->table_name, tables->alias));
@ -506,8 +556,12 @@ retry:
thd->open_tables= hash_tables->table;
lock= mysql_lock_tables(thd, &thd->open_tables, 1, 0, &need_reopen);
sql_handler_lock_error.init();
thd->push_internal_handler(&sql_handler_lock_error);
lock= mysql_lock_tables(thd, &thd->open_tables, 1, 0);
thd->pop_internal_handler();
/*
In 5.1 and earlier, mysql_lock_tables() could replace the TABLE
object with another one (reopen it). This is no longer the case
@ -517,7 +571,7 @@ retry:
/* Restore previous context. */
thd->open_tables= backup_open_tables;
if (need_reopen)
if (sql_handler_lock_error.need_reopen())
{
mysql_ha_close_table(thd, hash_tables);
goto retry;