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

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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

78
src/pl/plperl/plperl.c
View File

@ -3057,12 +3057,6 @@ plperl_spi_exec(char *query, int limit)
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();
}
PG_CATCH();
{
@ -3078,13 +3072,6 @@ plperl_spi_exec(char *query, int limit)
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();
/* Punt the error to Perl */
croak_cstr(edata->message);
@ -3296,12 +3283,6 @@ plperl_spi_query(char *query)
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();
}
PG_CATCH();
{
@ -3317,13 +3298,6 @@ plperl_spi_query(char *query)
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();
/* Punt the error to Perl */
croak_cstr(edata->message);
@ -3382,12 +3356,6 @@ plperl_spi_fetchrow(char *cursor)
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();
}
PG_CATCH();
{
@ -3403,13 +3371,6 @@ plperl_spi_fetchrow(char *cursor)
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();
/* Punt the error to Perl */
croak_cstr(edata->message);
@ -3543,12 +3504,6 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
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();
}
PG_CATCH();
{
@ -3574,13 +3529,6 @@ plperl_spi_prepare(char *query, int argc, SV **argv)
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();
/* Punt the error to Perl */
croak_cstr(edata->message);
@ -3694,12 +3642,6 @@ plperl_spi_exec_prepared(char *query, HV *attr, int argc, SV **argv)
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();
}
PG_CATCH();
{
@ -3715,13 +3657,6 @@ plperl_spi_exec_prepared(char *query, HV *attr, int argc, SV **argv)
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();
/* Punt the error to Perl */
croak_cstr(edata->message);
@ -3823,12 +3758,6 @@ plperl_spi_query_prepared(char *query, int argc, SV **argv)
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();
}
PG_CATCH();
{
@ -3844,13 +3773,6 @@ plperl_spi_query_prepared(char *query, int argc, SV **argv)
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();
/* Punt the error to Perl */
croak_cstr(edata->message);