database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-07-14 08:21:07 +03:00
Code Activity

Simplify code by getting rid of SPI_push, SPI_pop, SPI_restore_connection.

Browse Source 
The idea behind SPI_push was to allow transitioning back into an
"unconnected" state when a SPI-using procedure calls unrelated code that
might or might not invoke SPI.  That sounds good, but in practice the only
thing it does for us is to catch cases where a called SPI-using function
forgets to call SPI_connect --- which is a highly improbable failure mode,
since it would be exposed immediately by direct testing of said function.
As against that, we've had multiple bugs induced by forgetting to call
SPI_push/SPI_pop around code that might invoke SPI-using functions; these
are much harder to catch and indeed have gone undetected for years in some
cases.  And we've had to band-aid around some problems of this ilk by
introducing conditional push/pop pairs in some places, which really kind
of defeats the purpose altogether; if we can't draw bright lines between
connected and unconnected code, what's the point?

Hence, get rid of SPI_push[_conditional], SPI_pop[_conditional], and the
underlying state variable _SPI_curid.  It turns out SPI_restore_connection
can go away too, which is a nice side benefit since it was never more than
a kluge.  Provide no-op macros for the deleted functions so as to avoid an
API break for external modules.

A side effect of this removal is that SPI_palloc and allied functions no
longer permit being called when unconnected; they'll throw an error
instead.  The apparent usefulness of the previous behavior was a mirage
as well, because it was depended on by only a few places (which I fixed in
preceding commits), and it posed a risk of allocations being unexpectedly
long-lived if someone forgot a SPI_push call.

Discussion: <20808.1478481403@sss.pgh.pa.us>
This commit is contained in:
Tom Lane
2016-11-08 17:39:45 -05:00
parent 577f0bdd2b
commit 1833f1a1c3
12 changed files with 105 additions and 493 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
src/pl/plpython/plpy_exec.c
View File

@ -1103,8 +1103,6 @@ PLy_abort_open_subtransactions(int save_subxact_level)
RollbackAndReleaseCurrentSubTransaction();
SPI_restore_connection();
subtransactiondata = (PLySubtransactionData *) linitial(explicit_subtransactions);
explicit_subtransactions = list_delete_first(explicit_subtransactions);

13
src/pl/plpython/plpy_spi.c
View File

@ -516,12 +516,6 @@ PLy_spi_subtransaction_commit(MemoryContext oldcontext, ResourceOwner oldowner)
ReleaseCurrentSubTransaction();
MemoryContextSwitchTo(oldcontext);
CurrentResourceOwner = oldowner;
/*
* AtEOSubXact_SPI() should not have popped any SPI context, but just in
* case it did, make sure we remain connected.
*/
SPI_restore_connection();
}
void
@ -541,13 +535,6 @@ PLy_spi_subtransaction_abort(MemoryContext oldcontext, ResourceOwner oldowner)
MemoryContextSwitchTo(oldcontext);
CurrentResourceOwner = oldowner;
/*
* If AtEOSubXact_SPI() popped any SPI context of the subxact, it will
* have left us in a disconnected state. We need this hack to return to
* connected state.
*/
SPI_restore_connection();
/* Look up the correct exception */
entry = hash_search(PLy_spi_exceptions, &(edata->sqlerrcode),
HASH_FIND, NULL);

7
src/pl/plpython/plpy_subxactobject.c
View File

@ -7,7 +7,6 @@
#include "postgres.h"
#include "access/xact.h"
#include "executor/spi.h"
#include "utils/memutils.h"
#include "plpython.h"
@ -213,12 +212,6 @@ PLy_subtransaction_exit(PyObject *self, PyObject *args)
CurrentResourceOwner = subxactdata->oldowner;
pfree(subxactdata);
/*
* AtEOSubXact_SPI() should not have popped any SPI context, but just in
* case it did, make sure we remain connected.
*/
SPI_restore_connection();
Py_INCREF(Py_None);
return Py_None;
}