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mariadb/sql/transaction.cc
Konstantin Osipov 946fad3502 Draft patch that fixes and a sketches test cases for: 
Bug#20837 Apparent change of isolation level during transaction,
Bug#46527 COMMIT AND CHAIN RELEASE does not make sense,
Bug#53343 completion_type=1, COMMIT/ROLLBACK AND CHAIN don't 
preserve the isolation level
Bug#53346 completion_type has strange effect in a stored 
procedure/prepared statement

Make thd->tx_isolation mean strictly "current transaction 
isolation level"
Make thd->variables.tx_isolation mean "current session isolation
level".
The current transaction isolation level is now established
at transaction start. If there was a SET TRANSACTION
ISOLATION LEVEL statement, the value is taken from it.
Otherwise, the session value is used.
A change in a session value, made while a transaction is active,
whereas still allowed, no longer has any effect on the
current transaction isolation level. This is an incompatible
change.
A change in a session isolation level, made while there is
no active transaction, overrides SET TRANSACTION statement,
if there was any.
Changed the impelmentation to not look at @@session.completion_type
in the parser, and thus fixed Bug#53346.
Changed the parser to not allow AND NO CHAIN RELEASE,
and thus fixed Bug#46527.
Changed the transaction API to take the current transaction
isolation level into account:
- BEGIN/COMMIT now do preserve the current transaction
isolation level if chaining is on.
- implicit commit, XA COMMIT or XA ROLLBACK or autocommit don't.
2010-05-07 20:28:59 +04:00

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/* Copyright (C) 2008 Sun/MySQL
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
#ifdef USE_PRAGMA_IMPLEMENTATION
#pragma implementation // gcc: Class implementation
#endif
#include "sql_priv.h"
#include "transaction.h"
#include "rpl_handler.h"
/* Conditions under which the transaction state must not change. */
static bool trans_check(THD *thd)
{
enum xa_states xa_state= thd->transaction.xid_state.xa_state;
DBUG_ENTER("trans_check");
if (unlikely(thd->in_sub_stmt))
my_error(ER_COMMIT_NOT_ALLOWED_IN_SF_OR_TRG, MYF(0));
if (xa_state != XA_NOTR)
my_error(ER_XAER_RMFAIL, MYF(0), xa_state_names[xa_state]);
else
DBUG_RETURN(FALSE);
DBUG_RETURN(TRUE);
}
/**
Mark a XA transaction as rollback-only if the RM unilaterally
rolled back the transaction branch.
@note If a rollback was requested by the RM, this function sets
the appropriate rollback error code and transits the state
to XA_ROLLBACK_ONLY.
@return TRUE if transaction was rolled back or if the transaction
state is XA_ROLLBACK_ONLY. FALSE otherwise.
*/
static bool xa_trans_rolled_back(XID_STATE *xid_state)
{
if (xid_state->rm_error)
{
switch (xid_state->rm_error) {
case ER_LOCK_WAIT_TIMEOUT:
my_error(ER_XA_RBTIMEOUT, MYF(0));
break;
case ER_LOCK_DEADLOCK:
my_error(ER_XA_RBDEADLOCK, MYF(0));
break;
default:
my_error(ER_XA_RBROLLBACK, MYF(0));
}
xid_state->xa_state= XA_ROLLBACK_ONLY;
}
return (xid_state->xa_state == XA_ROLLBACK_ONLY);
}
/**
Begin a new transaction.
@note Beginning a transaction implicitly commits any current
transaction and releases existing locks.
@param thd Current thread
@param flags Transaction flags
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_begin(THD *thd, uint flags)
{
int res= FALSE;
DBUG_ENTER("trans_begin");
if (trans_check(thd))
DBUG_RETURN(TRUE);
thd->locked_tables_list.unlock_locked_tables(thd);
DBUG_ASSERT(!thd->locked_tables_mode);
if (thd->in_multi_stmt_transaction_mode() ||
(thd->variables.option_bits & OPTION_TABLE_LOCK))
{
thd->variables.option_bits&= ~OPTION_TABLE_LOCK;
thd->server_status&= ~SERVER_STATUS_IN_TRANS;
res= test(ha_commit_trans(thd, TRUE));
}
thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_KEEP_LOG);
thd->transaction.all.modified_non_trans_table= FALSE;
if (res)
DBUG_RETURN(TRUE);
/*
Release transactional metadata locks only after the
transaction has been committed.
*/
thd->mdl_context.release_transactional_locks();
thd->variables.option_bits|= OPTION_BEGIN;
thd->server_status|= SERVER_STATUS_IN_TRANS;
if (flags & MYSQL_START_TRANS_OPT_WITH_CONS_SNAPSHOT)
res= ha_start_consistent_snapshot(thd);
DBUG_RETURN(test(res));
}
/**
Commit the current transaction, making its changes permanent.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_commit(THD *thd)
{
int res;
DBUG_ENTER("trans_commit");
if (trans_check(thd))
DBUG_RETURN(TRUE);
thd->server_status&= ~SERVER_STATUS_IN_TRANS;
res= ha_commit_trans(thd, TRUE);
if (res)
/*
if res is non-zero, then ha_commit_trans has rolled back the
transaction, so the hooks for rollback will be called.
*/
RUN_HOOK(transaction, after_rollback, (thd, FALSE));
else
RUN_HOOK(transaction, after_commit, (thd, FALSE));
thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_KEEP_LOG);
thd->transaction.all.modified_non_trans_table= FALSE;
thd->lex->start_transaction_opt= 0;
DBUG_RETURN(test(res));
}
/**
Implicitly commit the current transaction.
@note A implicit commit does not releases existing table locks.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_commit_implicit(THD *thd)
{
bool res= FALSE;
DBUG_ENTER("trans_commit_implicit");
if (trans_check(thd))
DBUG_RETURN(TRUE);
if (thd->in_multi_stmt_transaction_mode() ||
(thd->variables.option_bits & OPTION_TABLE_LOCK))
{
/* Safety if one did "drop table" on locked tables */
if (!thd->locked_tables_mode)
thd->variables.option_bits&= ~OPTION_TABLE_LOCK;
thd->server_status&= ~SERVER_STATUS_IN_TRANS;
res= test(ha_commit_trans(thd, TRUE));
}
thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_KEEP_LOG);
thd->transaction.all.modified_non_trans_table= FALSE;
/*
Upon implicit commit, reset the current transaction
isolation level. We do not care about
@@session.completion_type since it's documented
to not have any effect on implicit commit.
*/
thd->tx_isolation= (enum_tx_isolation) thd->variables.tx_isolation;
DBUG_RETURN(res);
}
/**
Rollback the current transaction, canceling its changes.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_rollback(THD *thd)
{
int res;
DBUG_ENTER("trans_rollback");
if (trans_check(thd))
DBUG_RETURN(TRUE);
thd->server_status&= ~SERVER_STATUS_IN_TRANS;
res= ha_rollback_trans(thd, TRUE);
RUN_HOOK(transaction, after_rollback, (thd, FALSE));
thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_KEEP_LOG);
thd->transaction.all.modified_non_trans_table= FALSE;
thd->lex->start_transaction_opt= 0;
DBUG_RETURN(test(res));
}
/**
Commit the single statement transaction.
@note Note that if the autocommit is on, then the following call
inside InnoDB will commit or rollback the whole transaction
(= the statement). The autocommit mechanism built into InnoDB
is based on counting locks, but if the user has used LOCK
TABLES then that mechanism does not know to do the commit.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_commit_stmt(THD *thd)
{
DBUG_ENTER("trans_commit_stmt");
int res= FALSE;
if (thd->transaction.stmt.ha_list)
{
res= ha_commit_trans(thd, FALSE);
if (! thd->in_active_multi_stmt_transaction())
thd->tx_isolation= (enum_tx_isolation) thd->variables.tx_isolation;
}
if (res)
/*
if res is non-zero, then ha_commit_trans has rolled back the
transaction, so the hooks for rollback will be called.
*/
RUN_HOOK(transaction, after_rollback, (thd, FALSE));
else
RUN_HOOK(transaction, after_commit, (thd, FALSE));
DBUG_RETURN(test(res));
}
/**
Rollback the single statement transaction.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_rollback_stmt(THD *thd)
{
DBUG_ENTER("trans_rollback_stmt");
if (thd->transaction.stmt.ha_list)
{
ha_rollback_trans(thd, FALSE);
if (thd->transaction_rollback_request && !thd->in_sub_stmt)
ha_rollback_trans(thd, TRUE);
if (! thd->in_active_multi_stmt_transaction())
thd->tx_isolation= (enum_tx_isolation) thd->variables.tx_isolation;
}
RUN_HOOK(transaction, after_rollback, (thd, FALSE));
DBUG_RETURN(FALSE);
}
/* Find a named savepoint in the current transaction. */
static SAVEPOINT **
find_savepoint(THD *thd, LEX_STRING name)
{
SAVEPOINT **sv= &thd->transaction.savepoints;
while (*sv)
{
if (my_strnncoll(system_charset_info, (uchar *) name.str, name.length,
(uchar *) (*sv)->name, (*sv)->length) == 0)
break;
sv= &(*sv)->prev;
}
return sv;
}
/**
Set a named transaction savepoint.
@param thd Current thread
@param name Savepoint name
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_savepoint(THD *thd, LEX_STRING name)
{
SAVEPOINT **sv, *newsv;
DBUG_ENTER("trans_savepoint");
if (!(thd->in_multi_stmt_transaction_mode() || thd->in_sub_stmt) ||
!opt_using_transactions)
DBUG_RETURN(FALSE);
sv= find_savepoint(thd, name);
if (*sv) /* old savepoint of the same name exists */
{
newsv= *sv;
ha_release_savepoint(thd, *sv);
*sv= (*sv)->prev;
}
else if ((newsv= (SAVEPOINT *) alloc_root(&thd->transaction.mem_root,
savepoint_alloc_size)) == NULL)
{
my_error(ER_OUT_OF_RESOURCES, MYF(0));
DBUG_RETURN(TRUE);
}
newsv->name= strmake_root(&thd->transaction.mem_root, name.str, name.length);
newsv->length= name.length;
/*
if we'll get an error here, don't add new savepoint to the list.
we'll lose a little bit of memory in transaction mem_root, but it'll
be free'd when transaction ends anyway
*/
if (ha_savepoint(thd, newsv))
DBUG_RETURN(TRUE);
newsv->prev= thd->transaction.savepoints;
thd->transaction.savepoints= newsv;
/*
Remember the last acquired lock before the savepoint was set.
This is used as a marker to only release locks acquired after
the setting of this savepoint.
Note: this works just fine if we're under LOCK TABLES,
since mdl_savepoint() is guaranteed to be beyond
the last locked table. This allows to release some
locks acquired during LOCK TABLES.
*/
newsv->mdl_savepoint = thd->mdl_context.mdl_savepoint();
DBUG_RETURN(FALSE);
}
/**
Rollback a transaction to the named savepoint.
@note Modifications that the current transaction made to
rows after the savepoint was set are undone in the
rollback.
@note Savepoints that were set at a later time than the
named savepoint are deleted.
@param thd Current thread
@param name Savepoint name
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_rollback_to_savepoint(THD *thd, LEX_STRING name)
{
int res= FALSE;
SAVEPOINT *sv= *find_savepoint(thd, name);
DBUG_ENTER("trans_rollback_to_savepoint");
if (sv == NULL)
{
my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "SAVEPOINT", name.str);
DBUG_RETURN(TRUE);
}
if (ha_rollback_to_savepoint(thd, sv))
res= TRUE;
else if (((thd->variables.option_bits & OPTION_KEEP_LOG) ||
thd->transaction.all.modified_non_trans_table) &&
!thd->slave_thread)
push_warning(thd, MYSQL_ERROR::WARN_LEVEL_WARN,
ER_WARNING_NOT_COMPLETE_ROLLBACK,
ER(ER_WARNING_NOT_COMPLETE_ROLLBACK));
thd->transaction.savepoints= sv;
/*
Release metadata locks that were acquired during this savepoint unit.
*/
if (!res)
thd->mdl_context.rollback_to_savepoint(sv->mdl_savepoint);
DBUG_RETURN(test(res));
}
/**
Remove the named savepoint from the set of savepoints of
the current transaction.
@note No commit or rollback occurs. It is an error if the
savepoint does not exist.
@param thd Current thread
@param name Savepoint name
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_release_savepoint(THD *thd, LEX_STRING name)
{
int res= FALSE;
SAVEPOINT *sv= *find_savepoint(thd, name);
DBUG_ENTER("trans_release_savepoint");
if (sv == NULL)
{
my_error(ER_SP_DOES_NOT_EXIST, MYF(0), "SAVEPOINT", name.str);
DBUG_RETURN(TRUE);
}
if (ha_release_savepoint(thd, sv))
res= TRUE;
thd->transaction.savepoints= sv->prev;
DBUG_RETURN(test(res));
}
/**
Starts an XA transaction with the given xid value.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_xa_start(THD *thd)
{
enum xa_states xa_state= thd->transaction.xid_state.xa_state;
DBUG_ENTER("trans_xa_start");
if (xa_state == XA_IDLE && thd->lex->xa_opt == XA_RESUME)
{
bool not_equal= !thd->transaction.xid_state.xid.eq(thd->lex->xid);
if (not_equal)
my_error(ER_XAER_NOTA, MYF(0));
else
thd->transaction.xid_state.xa_state= XA_ACTIVE;
DBUG_RETURN(not_equal);
}
/* TODO: JOIN is not supported yet. */
if (thd->lex->xa_opt != XA_NONE)
my_error(ER_XAER_INVAL, MYF(0));
else if (xa_state != XA_NOTR)
my_error(ER_XAER_RMFAIL, MYF(0), xa_state_names[xa_state]);
else if (thd->locked_tables_mode || thd->in_active_multi_stmt_transaction())
my_error(ER_XAER_OUTSIDE, MYF(0));
else if (xid_cache_search(thd->lex->xid))
my_error(ER_XAER_DUPID, MYF(0));
else if (!trans_begin(thd))
{
DBUG_ASSERT(thd->transaction.xid_state.xid.is_null());
thd->transaction.xid_state.xa_state= XA_ACTIVE;
thd->transaction.xid_state.rm_error= 0;
thd->transaction.xid_state.xid.set(thd->lex->xid);
xid_cache_insert(&thd->transaction.xid_state);
DBUG_RETURN(FALSE);
}
DBUG_RETURN(TRUE);
}
/**
Put a XA transaction in the IDLE state.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_xa_end(THD *thd)
{
DBUG_ENTER("trans_xa_end");
/* TODO: SUSPEND and FOR MIGRATE are not supported yet. */
if (thd->lex->xa_opt != XA_NONE)
my_error(ER_XAER_INVAL, MYF(0));
else if (thd->transaction.xid_state.xa_state != XA_ACTIVE)
my_error(ER_XAER_RMFAIL, MYF(0),
xa_state_names[thd->transaction.xid_state.xa_state]);
else if (!thd->transaction.xid_state.xid.eq(thd->lex->xid))
my_error(ER_XAER_NOTA, MYF(0));
else if (!xa_trans_rolled_back(&thd->transaction.xid_state))
thd->transaction.xid_state.xa_state= XA_IDLE;
DBUG_RETURN(thd->transaction.xid_state.xa_state != XA_IDLE);
}
/**
Put a XA transaction in the PREPARED state.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_xa_prepare(THD *thd)
{
DBUG_ENTER("trans_xa_prepare");
if (thd->transaction.xid_state.xa_state != XA_IDLE)
my_error(ER_XAER_RMFAIL, MYF(0),
xa_state_names[thd->transaction.xid_state.xa_state]);
else if (!thd->transaction.xid_state.xid.eq(thd->lex->xid))
my_error(ER_XAER_NOTA, MYF(0));
else if (ha_prepare(thd))
{
xid_cache_delete(&thd->transaction.xid_state);
thd->transaction.xid_state.xa_state= XA_NOTR;
my_error(ER_XA_RBROLLBACK, MYF(0));
}
else
thd->transaction.xid_state.xa_state= XA_PREPARED;
DBUG_RETURN(thd->transaction.xid_state.xa_state != XA_PREPARED);
}
/**
Commit and terminate the a XA transaction.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_xa_commit(THD *thd)
{
bool res= TRUE;
enum xa_states xa_state= thd->transaction.xid_state.xa_state;
DBUG_ENTER("trans_xa_commit");
if (!thd->transaction.xid_state.xid.eq(thd->lex->xid))
{
XID_STATE *xs= xid_cache_search(thd->lex->xid);
res= !xs || xs->in_thd;
if (res)
my_error(ER_XAER_NOTA, MYF(0));
else
{
res= xa_trans_rolled_back(xs);
ha_commit_or_rollback_by_xid(thd->lex->xid, !res);
xid_cache_delete(xs);
}
DBUG_RETURN(res);
}
if (xa_trans_rolled_back(&thd->transaction.xid_state))
{
if ((res= test(ha_rollback_trans(thd, TRUE))))
my_error(ER_XAER_RMERR, MYF(0));
}
else if (xa_state == XA_IDLE && thd->lex->xa_opt == XA_ONE_PHASE)
{
int r= ha_commit_trans(thd, TRUE);
if ((res= test(r)))
my_error(r == 1 ? ER_XA_RBROLLBACK : ER_XAER_RMERR, MYF(0));
}
else if (xa_state == XA_PREPARED && thd->lex->xa_opt == XA_NONE)
{
if (thd->global_read_lock.wait_if_global_read_lock(thd, FALSE, FALSE))
{
ha_rollback_trans(thd, TRUE);
my_error(ER_XAER_RMERR, MYF(0));
}
else
{
res= test(ha_commit_one_phase(thd, 1));
if (res)
my_error(ER_XAER_RMERR, MYF(0));
thd->global_read_lock.start_waiting_global_read_lock(thd);
}
}
else
{
my_error(ER_XAER_RMFAIL, MYF(0), xa_state_names[xa_state]);
DBUG_RETURN(TRUE);
}
thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_KEEP_LOG);
thd->transaction.all.modified_non_trans_table= FALSE;
thd->server_status&= ~SERVER_STATUS_IN_TRANS;
xid_cache_delete(&thd->transaction.xid_state);
thd->transaction.xid_state.xa_state= XA_NOTR;
DBUG_RETURN(res);
}
/**
Roll back and terminate a XA transaction.
@param thd Current thread
@retval FALSE Success
@retval TRUE Failure
*/
bool trans_xa_rollback(THD *thd)
{
bool res= TRUE;
enum xa_states xa_state= thd->transaction.xid_state.xa_state;
DBUG_ENTER("trans_xa_rollback");
if (!thd->transaction.xid_state.xid.eq(thd->lex->xid))
{
XID_STATE *xs= xid_cache_search(thd->lex->xid);
if (!xs || xs->in_thd)
my_error(ER_XAER_NOTA, MYF(0));
else
{
xa_trans_rolled_back(xs);
ha_commit_or_rollback_by_xid(thd->lex->xid, 0);
xid_cache_delete(xs);
}
DBUG_RETURN(thd->stmt_da->is_error());
}
if (xa_state != XA_IDLE && xa_state != XA_PREPARED && xa_state != XA_ROLLBACK_ONLY)
{
my_error(ER_XAER_RMFAIL, MYF(0), xa_state_names[xa_state]);
DBUG_RETURN(TRUE);
}
/*
Resource Manager error is meaningless at this point, as we perform
explicit rollback request by user. We must reset rm_error before
calling ha_rollback(), so thd->transaction.xid structure gets reset
by ha_rollback()/THD::transaction::cleanup().
*/
thd->transaction.xid_state.rm_error= 0;
if ((res= test(ha_rollback_trans(thd, TRUE))))
my_error(ER_XAER_RMERR, MYF(0));
thd->variables.option_bits&= ~(OPTION_BEGIN | OPTION_KEEP_LOG);
thd->transaction.all.modified_non_trans_table= FALSE;
thd->server_status&= ~SERVER_STATUS_IN_TRANS;
xid_cache_delete(&thd->transaction.xid_state);
thd->transaction.xid_state.xa_state= XA_NOTR;
DBUG_RETURN(res);
}
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