@ -356,7 +356,7 @@ static const internalPQconninfoOption PQconninfoOptions[] = {
{ " target_session_attrs " , " PGTARGETSESSIONATTRS " ,
DefaultTargetSessionAttrs , NULL ,
" Target-Session-Attrs " , " " , 11 , /* sizeof("read-write") = 11 */
" Target-Session-Attrs " , " " , 15 , /* sizeof("prefer-standby") = 15 */
offsetof ( struct pg_conn , target_session_attrs ) } ,
/* Terminating entry --- MUST BE LAST */
@ -583,6 +583,8 @@ pqDropServerData(PGconn *conn)
conn - > pstatus = NULL ;
conn - > client_encoding = PG_SQL_ASCII ;
conn - > std_strings = false ;
conn - > default_transaction_read_only = PG_BOOL_UNKNOWN ;
conn - > in_hot_standby = PG_BOOL_UNKNOWN ;
conn - > sversion = 0 ;
/* Drop large-object lookup data */
@ -1389,33 +1391,46 @@ connectOptions2(PGconn *conn)
}
/*
* Resolve special " auto " client_encoding from the locale
*/
if ( conn - > client_encoding_initial & &
strcmp ( conn - > client_encoding_initial , " auto " ) = = 0 )
{
free ( conn - > client_encoding_initial ) ;
conn - > client_encoding_initial = strdup ( pg_encoding_to_char ( pg_get_encoding_from_locale ( NULL , true ) ) ) ;
if ( ! conn - > client_encoding_initial )
goto oom_error ;
}
/*
* Validate target_session_attrs option .
* validate target_session_attrs option , and set target_server_type
*/
if ( conn - > target_session_attrs )
{
if ( strcmp ( conn - > target_session_attrs , " any " ) ! = 0
& & strcmp ( conn - > target_session_attrs , " read-write " ) ! = 0 )
if ( strcmp ( conn - > target_session_attrs , " any " ) = = 0 )
conn - > target_server_type = SERVER_TYPE_ANY ;
else if ( strcmp ( conn - > target_session_attrs , " read-write " ) = = 0 )
conn - > target_server_type = SERVER_TYPE_READ_WRITE ;
else if ( strcmp ( conn - > target_session_attrs , " read-only " ) = = 0 )
conn - > target_server_type = SERVER_TYPE_READ_ONLY ;
else if ( strcmp ( conn - > target_session_attrs , " primary " ) = = 0 )
conn - > target_server_type = SERVER_TYPE_PRIMARY ;
else if ( strcmp ( conn - > target_session_attrs , " standby " ) = = 0 )
conn - > target_server_type = SERVER_TYPE_STANDBY ;
else if ( strcmp ( conn - > target_session_attrs , " prefer-standby " ) = = 0 )
conn - > target_server_type = SERVER_TYPE_PREFER_STANDBY ;
else
{
conn - > status = CONNECTION_BAD ;
appendPQExpBuffer ( & conn - > errorMessage ,
libpq_gettext ( " invalid %s value: \" %s \" \n " ) ,
" target_settion_attrs " ,
" target_sess ion_attrs " ,
conn - > target_session_attrs ) ;
return false ;
}
}
else
conn - > target_server_type = SERVER_TYPE_ANY ;
/*
* Resolve special " auto " client_encoding from the locale
*/
if ( conn - > client_encoding_initial & &
strcmp ( conn - > client_encoding_initial , " auto " ) = = 0 )
{
free ( conn - > client_encoding_initial ) ;
conn - > client_encoding_initial = strdup ( pg_encoding_to_char ( pg_get_encoding_from_locale ( NULL , true ) ) ) ;
if ( ! conn - > client_encoding_initial )
goto oom_error ;
}
/*
* Only if we get this far is it appropriate to try to connect . ( We need a
@ -2057,6 +2072,10 @@ connectDBStart(PGconn *conn)
conn - > try_next_host = true ;
conn - > status = CONNECTION_NEEDED ;
/* Also reset the target_server_type state if needed */
if ( conn - > target_server_type = = SERVER_TYPE_PREFER_STANDBY_PASS2 )
conn - > target_server_type = SERVER_TYPE_PREFER_STANDBY ;
/*
* The code for processing CONNECTION_NEEDED state is in PQconnectPoll ( ) ,
* so that it can easily be re - executed if needed again during the
@ -2250,6 +2269,9 @@ PQconnectPoll(PGconn *conn)
/* These are reading states */
case CONNECTION_AWAITING_RESPONSE :
case CONNECTION_AUTH_OK :
case CONNECTION_CHECK_WRITABLE :
case CONNECTION_CONSUME :
case CONNECTION_CHECK_STANDBY :
{
/* Load waiting data */
int n = pqReadData ( conn ) ;
@ -2274,9 +2296,8 @@ PQconnectPoll(PGconn *conn)
/* Special cases: proceed without waiting. */
case CONNECTION_SSL_STARTUP :
case CONNECTION_NEEDED :
case CONNECTION_CHECK_WRITABLE :
case CONNECTION_CONSUME :
case CONNECTION_GSS_STARTUP :
case CONNECTION_CHECK_TARGET :
break ;
default :
@ -2311,15 +2332,28 @@ keep_going: /* We will come back to here until there is
int ret ;
char portstr [ MAXPGPATH ] ;
if ( conn - > whichhost + 1 > = conn - > nconnhost )
if ( conn - > whichhost + 1 < conn - > nconnhost )
conn - > whichhost + + ;
else
{
/*
* Oops , no more hosts . An appropriate error message is already
* set up , so just set the right status .
* Oops , no more hosts .
*
* If we are trying to connect in " prefer-standby " mode , then drop
* the standby requirement and start over .
*
* Otherwise , an appropriate error message is already set up , so
* we just need to set the right status .
*/
goto error_return ;
if ( conn - > target_server_type = = SERVER_TYPE_PREFER_STANDBY & &
conn - > nconnhost > 0 )
{
conn - > target_server_type = SERVER_TYPE_PREFER_STANDBY_PASS2 ;
conn - > whichhost = 0 ;
}
else
goto error_return ;
}
conn - > whichhost + + ;
/* Drop any address info for previous host */
release_conn_addrinfo ( conn ) ;
@ -3550,28 +3584,131 @@ keep_going: /* We will come back to here until there is
case CONNECTION_CHECK_TARGET :
{
/*
* If a read - write connection is required , see if we have one .
*
* Servers before 7.4 lack the transaction_read_only GUC , but
* by the same token they don ' t have any read - only mode , so we
* may just skip the test in that case .
* If a read - write , read - only , primary , or standby connection
* is required , see if we have one .
*/
if ( conn - > sversion > = 70400 & &
conn - > target_session_attrs ! = NULL & &
strcmp ( conn - > target_session_attrs , " read-write " ) = = 0 )
if ( conn - > target_server_type = = SERVER_TYPE_READ_WRITE | |
conn - > target_server_type = = SERVER_TYPE_READ_ONLY )
{
bool read_only_server ;
/*
* We use PQsendQueryContinue so that conn - > errorMessage
* does not get cleared . We need to preserve any error
* messages related to previous hosts we have tried and
* failed to connect to .
* If the server didn ' t report
* " default_transaction_read_only " or " in_hot_standby " at
* startup , we must determine its state by sending the
* query " SHOW transaction_read_only " . Servers before 7.4
* lack the transaction_read_only GUC , but by the same
* token they don ' t have any read - only mode , so we may
* just assume the results .
*/
conn - > status = CONNECTION_OK ;
if ( ! PQsendQueryContinue ( conn ,
" SHOW transaction_read_only " ) )
goto error_return ;
conn - > status = CONNECTION_CHECK_WRITABLE ;
return PGRES_POLLING_READING ;
if ( conn - > sversion < 70400 )
{
conn - > default_transaction_read_only = PG_BOOL_NO ;
conn - > in_hot_standby = PG_BOOL_NO ;
}
if ( conn - > default_transaction_read_only = = PG_BOOL_UNKNOWN | |
conn - > in_hot_standby = = PG_BOOL_UNKNOWN )
{
/*
* We use PQsendQueryContinue so that
* conn - > errorMessage does not get cleared . We need
* to preserve any error messages related to previous
* hosts we have tried and failed to connect to .
*/
conn - > status = CONNECTION_OK ;
if ( ! PQsendQueryContinue ( conn ,
" SHOW transaction_read_only " ) )
goto error_return ;
/* We'll return to this state when we have the answer */
conn - > status = CONNECTION_CHECK_WRITABLE ;
return PGRES_POLLING_READING ;
}
/* OK, we can make the test */
read_only_server =
( conn - > default_transaction_read_only = = PG_BOOL_YES | |
conn - > in_hot_standby = = PG_BOOL_YES ) ;
if ( ( conn - > target_server_type = = SERVER_TYPE_READ_WRITE ) ?
read_only_server : ! read_only_server )
{
/* Wrong server state, reject and try the next host */
if ( conn - > target_server_type = = SERVER_TYPE_READ_WRITE )
appendPQExpBufferStr ( & conn - > errorMessage ,
libpq_gettext ( " session is read-only \n " ) ) ;
else
appendPQExpBufferStr ( & conn - > errorMessage ,
libpq_gettext ( " session is not read-only \n " ) ) ;
/* Close connection politely. */
conn - > status = CONNECTION_OK ;
sendTerminateConn ( conn ) ;
/*
* Try next host if any , but we don ' t want to consider
* additional addresses for this host .
*/
conn - > try_next_host = true ;
goto keep_going ;
}
}
else if ( conn - > target_server_type = = SERVER_TYPE_PRIMARY | |
conn - > target_server_type = = SERVER_TYPE_STANDBY | |
conn - > target_server_type = = SERVER_TYPE_PREFER_STANDBY )
{
/*
* If the server didn ' t report " in_hot_standby " at
* startup , we must determine its state by sending the
* query " SELECT pg_catalog.pg_is_in_recovery() " . Servers
* before 9.0 don ' t have that function , but by the same
* token they don ' t have any standby mode , so we may just
* assume the result .
*/
if ( conn - > sversion < 90000 )
conn - > in_hot_standby = PG_BOOL_NO ;
if ( conn - > in_hot_standby = = PG_BOOL_UNKNOWN )
{
/*
* We use PQsendQueryContinue so that
* conn - > errorMessage does not get cleared . We need
* to preserve any error messages related to previous
* hosts we have tried and failed to connect to .
*/
conn - > status = CONNECTION_OK ;
if ( ! PQsendQueryContinue ( conn ,
" SELECT pg_catalog.pg_is_in_recovery() " ) )
goto error_return ;
/* We'll return to this state when we have the answer */
conn - > status = CONNECTION_CHECK_STANDBY ;
return PGRES_POLLING_READING ;
}
/* OK, we can make the test */
if ( ( conn - > target_server_type = = SERVER_TYPE_PRIMARY ) ?
( conn - > in_hot_standby = = PG_BOOL_YES ) :
( conn - > in_hot_standby = = PG_BOOL_NO ) )
{
/* Wrong server state, reject and try the next host */
if ( conn - > target_server_type = = SERVER_TYPE_PRIMARY )
appendPQExpBufferStr ( & conn - > errorMessage ,
libpq_gettext ( " server is in hot standby mode \n " ) ) ;
else
appendPQExpBufferStr ( & conn - > errorMessage ,
libpq_gettext ( " server is not in hot standby mode \n " ) ) ;
/* Close connection politely. */
conn - > status = CONNECTION_OK ;
sendTerminateConn ( conn ) ;
/*
* Try next host if any , but we don ' t want to consider
* additional addresses for this host .
*/
conn - > try_next_host = true ;
goto keep_going ;
}
}
/* We can release the address list now. */
@ -3617,6 +3754,14 @@ keep_going: /* We will come back to here until there is
case CONNECTION_CONSUME :
{
/*
* This state just makes sure the connection is idle after
* we ' ve obtained the result of a SHOW or SELECT query . Once
* we ' re clear , return to CONNECTION_CHECK_TARGET state to
* decide what to do next . We must transiently set status =
* CONNECTION_OK in order to use the result - consuming
* subroutines .
*/
conn - > status = CONNECTION_OK ;
if ( ! PQconsumeInput ( conn ) )
goto error_return ;
@ -3627,26 +3772,26 @@ keep_going: /* We will come back to here until there is
return PGRES_POLLING_READING ;
}
/*
* Call PQgetResult ( ) again to consume NULL result .
*/
/* Call PQgetResult() again until we get a NULL result */
res = PQgetResult ( conn ) ;
if ( res ! = NULL )
{
PQclear ( res ) ;
conn - > status = CONNECTION_CONSUME ;
goto keep_going ;
return PGRES_POLLING_READING ;
}
/* We can release the address list now. */
release_conn_addrinfo ( conn ) ;
/* We are open for business! */
conn - > status = CONNECTION_OK ;
return PGRES_POLLING_OK ;
conn - > status = CONNECTION_CHECK_TARGET ;
goto keep_going ;
}
case CONNECTION_CHECK_WRITABLE :
{
/*
* Waiting for result of " SHOW transaction_read_only " . We
* must transiently set status = CONNECTION_OK in order to use
* the result - consuming subroutines .
*/
conn - > status = CONNECTION_OK ;
if ( ! PQconsumeInput ( conn ) )
goto error_return ;
@ -3658,61 +3803,102 @@ keep_going: /* We will come back to here until there is
}
res = PQgetResult ( conn ) ;
if ( res & & ( PQresultStatus ( res ) = = PGRES_TUPLES_OK ) & &
if ( res & & PQresultStatus ( res ) = = PGRES_TUPLES_OK & &
PQntuples ( res ) = = 1 )
{
char * val ;
char * val = PQgetvalue ( res , 0 , 0 ) ;
val = PQgetvalue ( res , 0 , 0 ) ;
/*
* " transaction_read_only = on " proves that at least one
* of default_transaction_read_only and in_hot_standby is
* on , but we don ' t actually know which . We don ' t care
* though for the purpose of identifying a read - only
* session , so satisfy the CONNECTION_CHECK_TARGET code by
* claiming they are both on . On the other hand , if it ' s
* a read - write session , they are certainly both off .
*/
if ( strncmp ( val , " on " , 2 ) = = 0 )
{
/* Not writable; fail this connection. */
PQclear ( res ) ;
conn - > default_transaction_read_only = PG_BOOL_YES ;
conn - > in_hot_standby = PG_BOOL_YES ;
}
else
{
conn - > default_transaction_read_only = PG_BOOL_NO ;
conn - > in_hot_standby = PG_BOOL_NO ;
}
PQclear ( res ) ;
/* Append error report to conn->errorMessage. */
appendPQExpBufferStr ( & conn - > errorMessage ,
libpq_gettext ( " session is read-only \n " ) ) ;
/* Finish reading messages before continuing */
conn - > status = CONNECTION_CONSUME ;
goto keep_going ;
}
/* Close connection politely. */
conn - > status = CONNECTION_OK ;
sendTerminateConn ( conn ) ;
/* Something went wrong with "SHOW transaction_read_only" . */
if ( res )
PQclear ( res ) ;
/*
* Try next host if any , but we don ' t want to consider
* additional addresses for this host .
*/
conn - > try_next_host = true ;
goto keep_going ;
}
/* Append error report to conn->errorMessage. */
appendPQExpBufferStr ( & conn - > errorMessage ,
libpq_gettext ( " \" SHOW transaction_read_only \" failed \n " ) ) ;
/* Close connection politely. */
conn - > status = CONNECTION_OK ;
sendTerminateConn ( conn ) ;
/* Try next host. */
conn - > try_next_host = true ;
goto keep_going ;
}
/* Session is read-write, so we're good. */
case CONNECTION_CHECK_STANDBY :
{
/*
* Waiting for result of " SELECT pg_is_in_recovery() " . We
* must transiently set status = CONNECTION_OK in order to use
* the result - consuming subroutines .
*/
conn - > status = CONNECTION_OK ;
if ( ! PQconsumeInput ( conn ) )
goto error_return ;
if ( PQisBusy ( conn ) )
{
conn - > status = CONNECTION_CHECK_STANDBY ;
return PGRES_POLLING_READING ;
}
res = PQgetResult ( conn ) ;
if ( res & & PQresultStatus ( res ) = = PGRES_TUPLES_OK & &
PQntuples ( res ) = = 1 )
{
char * val = PQgetvalue ( res , 0 , 0 ) ;
if ( strncmp ( val , " t " , 1 ) = = 0 )
conn - > in_hot_standby = PG_BOOL_YES ;
else
conn - > in_hot_standby = PG_BOOL_NO ;
PQclear ( res ) ;
/*
* Finish reading any remaining messages before being
* considered as ready .
*/
/* Finish reading messages before continuing */
conn - > status = CONNECTION_CONSUME ;
goto keep_going ;
}
/*
* Something went wrong with " SHOW transaction_read_only " . We
* should try next addresses .
*/
/* Something went wrong with "SELECT pg_is_in_recovery()". */
if ( res )
PQclear ( res ) ;
/* Append error report to conn->errorMessage. */
appendPQExpBufferStr ( & conn - > errorMessage ,
libpq_gettext ( " test \" SHOW transaction_read_only \" failed \n " ) ) ;
libpq_gettext ( " \" SELECT pg_is_in_recovery() \" failed \n " ) ) ;
/* Close connection politely. */
conn - > status = CONNECTION_OK ;
sendTerminateConn ( conn ) ;
/* Try next address */
conn - > try_next_addr = true ;
/* Try next host. */
conn - > try_next_host = true ;
goto keep_going ;
}
@ -3859,6 +4045,8 @@ makeEmptyPGconn(void)
conn - > setenv_state = SETENV_STATE_IDLE ;
conn - > client_encoding = PG_SQL_ASCII ;
conn - > std_strings = false ; /* unless server says differently */
conn - > default_transaction_read_only = PG_BOOL_UNKNOWN ;
conn - > in_hot_standby = PG_BOOL_UNKNOWN ;
conn - > verbosity = PQERRORS_DEFAULT ;
conn - > show_context = PQSHOW_CONTEXT_ERRORS ;
conn - > sock = PGINVALID_SOCKET ;
Tom Lane
5 years ago