@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $ PostgreSQL : pgsql / src / interfaces / libpq / fe - connect . c , v 1.288 2004 / 10 / 29 19 : 30 : 02 momjian Exp $
* $ PostgreSQL : pgsql / src / interfaces / libpq / fe - connect . c , v 1.289 2004 / 10 / 30 23 : 11 : 26 tgl Exp $
*
* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
*/
@ -2189,19 +2189,55 @@ PQresetPoll(PGconn *conn)
return PGRES_POLLING_FAILED ;
}
/*
* PQcancelGet : get a PGcancel structure corresponding to a connection .
*
* A copy is needed to be able to cancel a running query from a different
* thread . If the same structure is used all structure members would have
* to be individually locked ( if the entire structure was locked , it would
* be impossible to cancel a synchronous query becuase the structure would
* have to stay locked for the duration of the query ) .
*/
PGcancel *
PQgetCancel ( PGconn * conn )
{
PGcancel * cancel ;
if ( ! conn )
return NULL ;
if ( conn - > sock < 0 )
return NULL ;
cancel = malloc ( sizeof ( PGcancel ) ) ;
if ( cancel = = NULL )
return NULL ;
memcpy ( & cancel - > raddr , & conn - > raddr , sizeof ( SockAddr ) ) ;
cancel - > be_pid = conn - > be_pid ;
cancel - > be_key = conn - > be_key ;
return cancel ;
}
/* PQfreeCancel: free a cancel structure */
void
PQfreeCancel ( PGcancel * cancel )
{
if ( cancel )
free ( cancel ) ;
}
/*
* PQrequestCancel : attempt to request cancellation of the current operation .
* PQcancel and PQrequestCancel : attempt to request cancellation of the
* current operation .
*
* The return value is TRUE if the cancel request was successfully
* dispatched , FALSE if not ( in which case conn - > errorMessage is set ) .
* dispatched , FALSE if not ( in which case an error message is available ) .
* Note : successful dispatch is no guarantee that there will be any effect at
* the backend . The application must read the operation result as usual .
*
* XXX it was a bad idea to have the error message returned in
* conn - > errorMessage , since it could overwrite a message already there .
* Would be better to return it in a char array passed by the caller .
*
* CAUTION : we want this routine to be safely callable from a signal handler
* ( for example , an application might want to call it in a SIGINT handler ) .
* This means we cannot use any C library routine that might be non - reentrant .
@ -2210,59 +2246,40 @@ PQresetPoll(PGconn *conn)
* error messages with strcpy / strcat is tedious but should be quite safe .
* We also save / restore errno in case the signal handler support doesn ' t .
*
* NOTE : this routine must not generate any error message longer than
* INITIAL_EXPBUFFER_SIZE ( currently 256 ) , since we dare not try to
* expand conn - > errorMessage !
* internal_cancel ( ) is an internal helper function to make code - sharing
* between the two versions of the cancel function possible .
*/
int
PQrequestCancel ( PGconn * conn )
static int
internal_cancel ( SockAddr * raddr , int be_pid , int be_key ,
char * errbuf , int errbufsize )
{
int save_errno = SOCK_ERRNO ;
int tmpsock = - 1 ;
char sebuf [ 256 ] ;
int maxlen ;
struct
{
uint32 packetlen ;
CancelRequestPacket cp ;
} crp ;
/* Check we have an open connection */
if ( ! conn )
return FALSE ;
if ( conn - > sock < 0 )
{
strcpy ( conn - > errorMessage . data ,
" PQrequestCancel() -- connection is not open \n " ) ;
conn - > errorMessage . len = strlen ( conn - > errorMessage . data ) ;
# ifdef WIN32
WSASetLastError ( save_errno ) ;
# else
errno = save_errno ;
# endif
return FALSE ;
}
/*
* We need to open a temporary connection to the postmaster . Use the
* information saved by connectDB to do this with only kernel calls .
* We need to open a temporary connection to the postmaster . Do
* this with only kernel calls .
*/
if ( ( tmpsock = socket ( conn - > raddr . addr . ss_family , SOCK_STREAM , 0 ) ) < 0 )
if ( ( tmpsock = socket ( raddr - > addr . ss_family , SOCK_STREAM , 0 ) ) < 0 )
{
strcpy ( conn - > errorMessage . data ,
" PQrequestCancel() -- socket() failed: " ) ;
StrNCpy ( errbuf , " PQcancel() -- socket() failed: " , errbufsize ) ;
goto cancel_errReturn ;
}
retry3 :
if ( connect ( tmpsock , ( struct sockaddr * ) & conn - > raddr . addr ,
conn - > raddr . salen ) < 0 )
if ( connect ( tmpsock , ( struct sockaddr * ) & raddr - > addr ,
raddr - > salen ) < 0 )
{
if ( SOCK_ERRNO = = EINTR )
/* Interrupted system call - we'll just try again */
goto retry3 ;
strcpy ( conn - > errorMessage . data ,
" PQrequestCancel() -- connect() failed: " ) ;
StrNCpy ( errbuf , " PQcancel() -- connect() failed: " , errbufsize ) ;
goto cancel_errReturn ;
}
@ -2274,8 +2291,8 @@ retry3:
crp . packetlen = htonl ( ( uint32 ) sizeof ( crp ) ) ;
crp . cp . cancelRequestCode = ( MsgType ) htonl ( CANCEL_REQUEST_CODE ) ;
crp . cp . backendPID = htonl ( conn - > be_pid ) ;
crp . cp . cancelAuthCode = htonl ( conn - > be_key ) ;
crp . cp . backendPID = htonl ( be_pid ) ;
crp . cp . cancelAuthCode = htonl ( be_key ) ;
retry4 :
if ( send ( tmpsock , ( char * ) & crp , sizeof ( crp ) , 0 ) ! = ( int ) sizeof ( crp ) )
@ -2283,8 +2300,7 @@ retry4:
if ( SOCK_ERRNO = = EINTR )
/* Interrupted system call - we'll just try again */
goto retry4 ;
strcpy ( conn - > errorMessage . data ,
" PQrequestCancel() -- send() failed: " ) ;
StrNCpy ( errbuf , " PQcancel() -- send() failed: " , errbufsize ) ;
goto cancel_errReturn ;
}
@ -2316,21 +2332,90 @@ retry5:
return TRUE ;
cancel_errReturn :
strcat ( conn - > errorMessage . data , SOCK_STRERROR ( SOCK_ERRNO , sebuf , sizeof ( sebuf ) ) ) ;
strcat ( conn - > errorMessage . data , " \n " ) ;
conn - > errorMessage . len = strlen ( conn - > errorMessage . data ) ;
if ( tmpsock > = 0 )
/*
* Make sure we don ' t overflow the error buffer . Leave space for
* the \ n at the end , and for the terminating zero .
*/
maxlen = errbufsize - strlen ( errbuf ) - 2 ;
if ( maxlen > = 0 )
{
strncat ( errbuf , SOCK_STRERROR ( SOCK_ERRNO , sebuf , sizeof ( sebuf ) ) ,
maxlen ) ;
strcat ( errbuf , " \n " ) ;
}
if ( tmpsock > = 0 )
closesocket ( tmpsock ) ;
# ifdef WIN32
WSASetLastError ( save_errno ) ;
WSASetLastError ( save_errno ) ;
# else
errno = save_errno ;
errno = save_errno ;
# endif
}
return FALSE ;
}
/*
* PQcancel : request query cancel
*
* Returns TRUE if able to send the cancel request , FALSE if not .
*
* On failure , an error message is stored in * errbuf , which must be of size
* errbufsize ( recommended size is 256 bytes ) . * errbuf is not changed on
* success return .
*/
int
PQcancel ( PGcancel * cancel , char * errbuf , int errbufsize )
{
if ( ! cancel )
{
StrNCpy ( errbuf , " PQcancel() -- no cancel object supplied " , errbufsize ) ;
return FALSE ;
}
return internal_cancel ( & cancel - > raddr , cancel - > be_pid , cancel - > be_key ,
errbuf , errbufsize ) ;
}
/*
* PQrequestCancel : old , not thread - safe function for requesting query cancel
*
* Returns TRUE if able to send the cancel request , FALSE if not .
*
* On failure , the error message is saved in conn - > errorMessage ; this means
* that this can ' t be used when there might be other active operations on
* the connection object .
*
* NOTE : error messages will be cut off at the current size of the
* error message buffer , since we dare not try to expand conn - > errorMessage !
*/
int
PQrequestCancel ( PGconn * conn )
{
int r ;
/* Check we have an open connection */
if ( ! conn )
return FALSE ;
if ( conn - > sock < 0 )
{
StrNCpy ( conn - > errorMessage . data ,
" PQrequestCancel() -- connection is not open \n " ,
conn - > errorMessage . maxlen ) ;
conn - > errorMessage . len = strlen ( conn - > errorMessage . data ) ;
return FALSE ;
}
r = internal_cancel ( & conn - > raddr , conn - > be_pid , conn - > be_key ,
conn - > errorMessage . data , conn - > errorMessage . maxlen ) ;
if ( ! r )
conn - > errorMessage . len = strlen ( conn - > errorMessage . data ) ;
return r ;
}
/*
* pqPacketSend ( ) - - convenience routine to send a message to server .
Tom Lane
21 years ago