@ -52,6 +52,8 @@
# include "access/xact.h"
# include "access/xlog.h"
# include "catalog/catalog.h"
# include "catalog/pg_authid.h"
# include "commands/dbcommands.h"
# include "miscadmin.h"
# include "pgstat.h"
# include "storage/proc.h"
@ -2970,6 +2972,118 @@ CountOtherDBBackends(Oid databaseId, int *nbackends, int *nprepared)
return true ; /* timed out, still conflicts */
}
/*
* Terminate existing connections to the specified database . This routine
* is used by the DROP DATABASE command when user has asked to forcefully
* drop the database .
*
* The current backend is always ignored ; it is caller ' s responsibility to
* check whether the current backend uses the given DB , if it ' s important .
*
* It doesn ' t allow to terminate the connections even if there is a one
* backend with the prepared transaction in the target database .
*/
void
TerminateOtherDBBackends ( Oid databaseId )
{
ProcArrayStruct * arrayP = procArray ;
List * pids = NIL ;
int nprepared = 0 ;
int i ;
LWLockAcquire ( ProcArrayLock , LW_SHARED ) ;
for ( i = 0 ; i < procArray - > numProcs ; i + + )
{
int pgprocno = arrayP - > pgprocnos [ i ] ;
PGPROC * proc = & allProcs [ pgprocno ] ;
if ( proc - > databaseId ! = databaseId )
continue ;
if ( proc = = MyProc )
continue ;
if ( proc - > pid ! = 0 )
pids = lappend_int ( pids , proc - > pid ) ;
else
nprepared + + ;
}
LWLockRelease ( ProcArrayLock ) ;
if ( nprepared > 0 )
ereport ( ERROR ,
( errcode ( ERRCODE_OBJECT_IN_USE ) ,
errmsg ( " database \" %s \" is being used by prepared transaction " ,
get_database_name ( databaseId ) ) ,
errdetail_plural ( " There is %d prepared transaction using the database. " ,
" There are %d prepared transactions using the database. " ,
nprepared ,
nprepared ) ) ) ;
if ( pids )
{
ListCell * lc ;
/*
* Check whether we have the necessary rights to terminate other
* sessions . We don ' t terminate any session untill we ensure that we
* have rights on all the sessions to be terminated . These checks are
* the same as we do in pg_terminate_backend .
*
* In this case we don ' t raise some warnings - like " PID %d is not a
* PostgreSQL server process " , because for us already finished session
* is not a problem .
*/
foreach ( lc , pids )
{
int pid = lfirst_int ( lc ) ;
PGPROC * proc = BackendPidGetProc ( pid ) ;
if ( proc ! = NULL )
{
/* Only allow superusers to signal superuser-owned backends. */
if ( superuser_arg ( proc - > roleId ) & & ! superuser ( ) )
ereport ( ERROR ,
( errcode ( ERRCODE_INSUFFICIENT_PRIVILEGE ) ,
( errmsg ( " must be a superuser to terminate superuser process " ) ) ) ) ;
/* Users can signal backends they have role membership in. */
if ( ! has_privs_of_role ( GetUserId ( ) , proc - > roleId ) & &
! has_privs_of_role ( GetUserId ( ) , DEFAULT_ROLE_SIGNAL_BACKENDID ) )
ereport ( ERROR ,
( errcode ( ERRCODE_INSUFFICIENT_PRIVILEGE ) ,
( errmsg ( " must be a member of the role whose process is being terminated or member of pg_signal_backend " ) ) ) ) ;
}
}
/*
* There ' s a race condition here : once we release the ProcArrayLock ,
* it ' s possible for the session to exit before we issue kill . That
* race condition possibility seems too unlikely to worry about . See
* pg_signal_backend .
*/
foreach ( lc , pids )
{
int pid = lfirst_int ( lc ) ;
PGPROC * proc = BackendPidGetProc ( pid ) ;
if ( proc ! = NULL )
{
/*
* If we have setsid ( ) , signal the backend ' s whole process
* group
*/
# ifdef HAVE_SETSID
( void ) kill ( - pid , SIGTERM ) ;
# else
( void ) kill ( pid , SIGTERM ) ;
# endif
}
}
}
}
/*
* ProcArraySetReplicationSlotXmin
*
Amit Kapila
6 years ago