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postgresql/contrib/intarray/_intbig_gist.c
Tom Lane 8aac9759bb Remove unnecessary pfree() in g_intbig_compress(). 
GiST compress functions (like all GiST opclass functions) are
supposed to be called in short-lived memory contexts, so that
minor memory leaks in them are not of concern, and indeed
explicit pfree's are likely slightly counterproductive.
But this one in g_intbig_compress() is more than
slightly counterproductive, because it's guarded by
"if (in != DatumGetArrayTypeP(entry->key))" which means
that if this test succeeds, we've detoasted the datum twice.
(And to add insult to injury, the extra detoast result is
leaked.)  Let's just drop the whole stanza, relying on the
GiST temporary context mechanism to clean up in good time.

The analogous bit in g_int_compress() is
       if (r != (ArrayType *) DatumGetPointer(entry->key))
           pfree(r);
which doesn't have the gratuitous-detoast problem so
I left it alone.  Perhaps there is a case for removing
unnecessary pfree's more widely, but I'm not sure if it's
worth the code churn.

The potential extra decompress seems expensive enough to
justify calling this a (minor) performance bug and
back-patching.

Konstantin Knizhnik, Matthias van de Meent, Tom Lane

Discussion: https://postgr.es/m/CAEze2Wi86=DxErfvf+SCB2UKmU2amKOF60BKuJOX=w-RojRn0A@mail.gmail.com
2023-07-13 13:07:51 -04:00

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/*
* contrib/intarray/_intbig_gist.c
*/
#include "postgres.h"
#include <math.h>
#include "_int.h"
#include "access/gist.h"
#include "access/reloptions.h"
#include "access/stratnum.h"
#include "port/pg_bitutils.h"
#define GETENTRY(vec,pos) ((GISTTYPE *) DatumGetPointer((vec)->vector[(pos)].key))
/*
** _intbig methods
*/
PG_FUNCTION_INFO_V1(g_intbig_consistent);
PG_FUNCTION_INFO_V1(g_intbig_compress);
PG_FUNCTION_INFO_V1(g_intbig_decompress);
PG_FUNCTION_INFO_V1(g_intbig_penalty);
PG_FUNCTION_INFO_V1(g_intbig_picksplit);
PG_FUNCTION_INFO_V1(g_intbig_union);
PG_FUNCTION_INFO_V1(g_intbig_same);
PG_FUNCTION_INFO_V1(g_intbig_options);
PG_FUNCTION_INFO_V1(_intbig_in);
PG_FUNCTION_INFO_V1(_intbig_out);
Datum
_intbig_in(PG_FUNCTION_ARGS)
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot accept a value of type %s", "intbig_gkey")));
PG_RETURN_VOID(); /* keep compiler quiet */
}
Datum
_intbig_out(PG_FUNCTION_ARGS)
{
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("cannot display a value of type %s", "intbig_gkey")));
PG_RETURN_VOID(); /* keep compiler quiet */
}
static GISTTYPE *
_intbig_alloc(bool allistrue, int siglen, BITVECP sign)
{
int flag = allistrue ? ALLISTRUE : 0;
int size = CALCGTSIZE(flag, siglen);
GISTTYPE *res = (GISTTYPE *) palloc(size);
SET_VARSIZE(res, size);
res->flag = flag;
if (!allistrue)
{
if (sign)
memcpy(GETSIGN(res), sign, siglen);
else
memset(GETSIGN(res), 0, siglen);
}
return res;
}
/*********************************************************************
** intbig functions
*********************************************************************/
static bool
_intbig_overlap(GISTTYPE *a, ArrayType *b, int siglen)
{
int num = ARRNELEMS(b);
int32 *ptr = ARRPTR(b);
CHECKARRVALID(b);
while (num--)
{
if (GETBIT(GETSIGN(a), HASHVAL(*ptr, siglen)))
return true;
ptr++;
}
return false;
}
static bool
_intbig_contains(GISTTYPE *a, ArrayType *b, int siglen)
{
int num = ARRNELEMS(b);
int32 *ptr = ARRPTR(b);
CHECKARRVALID(b);
while (num--)
{
if (!GETBIT(GETSIGN(a), HASHVAL(*ptr, siglen)))
return false;
ptr++;
}
return true;
}
Datum
g_intbig_same(PG_FUNCTION_ARGS)
{
GISTTYPE *a = (GISTTYPE *) PG_GETARG_POINTER(0);
GISTTYPE *b = (GISTTYPE *) PG_GETARG_POINTER(1);
bool *result = (bool *) PG_GETARG_POINTER(2);
int siglen = GET_SIGLEN();
if (ISALLTRUE(a) && ISALLTRUE(b))
*result = true;
else if (ISALLTRUE(a))
*result = false;
else if (ISALLTRUE(b))
*result = false;
else
{
int32 i;
BITVECP sa = GETSIGN(a),
sb = GETSIGN(b);
*result = true;
LOOPBYTE(siglen)
{
if (sa[i] != sb[i])
{
*result = false;
break;
}
}
}
PG_RETURN_POINTER(result);
}
Datum
g_intbig_compress(PG_FUNCTION_ARGS)
{
GISTENTRY *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
int siglen = GET_SIGLEN();
if (entry->leafkey)
{
GISTENTRY *retval;
ArrayType *in = DatumGetArrayTypeP(entry->key);
int32 *ptr;
int num;
GISTTYPE *res = _intbig_alloc(false, siglen, NULL);
CHECKARRVALID(in);
if (ARRISEMPTY(in))
{
ptr = NULL;
num = 0;
}
else
{
ptr = ARRPTR(in);
num = ARRNELEMS(in);
}
while (num--)
{
HASH(GETSIGN(res), *ptr, siglen);
ptr++;
}
retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
gistentryinit(*retval, PointerGetDatum(res),
entry->rel, entry->page,
entry->offset, false);
PG_RETURN_POINTER(retval);
}
else if (!ISALLTRUE(DatumGetPointer(entry->key)))
{
GISTENTRY *retval;
int i;
BITVECP sign = GETSIGN(DatumGetPointer(entry->key));
GISTTYPE *res;
LOOPBYTE(siglen)
{
if ((sign[i] & 0xff) != 0xff)
PG_RETURN_POINTER(entry);
}
res = _intbig_alloc(true, siglen, sign);
retval = (GISTENTRY *) palloc(sizeof(GISTENTRY));
gistentryinit(*retval, PointerGetDatum(res),
entry->rel, entry->page,
entry->offset, false);
PG_RETURN_POINTER(retval);
}
PG_RETURN_POINTER(entry);
}
static int32
sizebitvec(BITVECP sign, int siglen)
{
return pg_popcount(sign, siglen);
}
static int
hemdistsign(BITVECP a, BITVECP b, int siglen)
{
int i,
diff,
dist = 0;
LOOPBYTE(siglen)
{
diff = (unsigned char) (a[i] ^ b[i]);
/* Using the popcount functions here isn't likely to win */
dist += pg_number_of_ones[diff];
}
return dist;
}
static int
hemdist(GISTTYPE *a, GISTTYPE *b, int siglen)
{
if (ISALLTRUE(a))
{
if (ISALLTRUE(b))
return 0;
else
return SIGLENBIT(siglen) - sizebitvec(GETSIGN(b), siglen);
}
else if (ISALLTRUE(b))
return SIGLENBIT(siglen) - sizebitvec(GETSIGN(a), siglen);
return hemdistsign(GETSIGN(a), GETSIGN(b), siglen);
}
Datum
g_intbig_decompress(PG_FUNCTION_ARGS)
{
PG_RETURN_DATUM(PG_GETARG_DATUM(0));
}
static int32
unionkey(BITVECP sbase, GISTTYPE *add, int siglen)
{
int32 i;
BITVECP sadd = GETSIGN(add);
if (ISALLTRUE(add))
return 1;
LOOPBYTE(siglen)
sbase[i] |= sadd[i];
return 0;
}
Datum
g_intbig_union(PG_FUNCTION_ARGS)
{
GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
int *size = (int *) PG_GETARG_POINTER(1);
int siglen = GET_SIGLEN();
int32 i;
GISTTYPE *result = _intbig_alloc(false, siglen, NULL);
BITVECP base = GETSIGN(result);
for (i = 0; i < entryvec->n; i++)
{
if (unionkey(base, GETENTRY(entryvec, i), siglen))
{
result->flag |= ALLISTRUE;
SET_VARSIZE(result, CALCGTSIZE(ALLISTRUE, siglen));
break;
}
}
*size = VARSIZE(result);
PG_RETURN_POINTER(result);
}
Datum
g_intbig_penalty(PG_FUNCTION_ARGS)
{
GISTENTRY *origentry = (GISTENTRY *) PG_GETARG_POINTER(0); /* always ISSIGNKEY */
GISTENTRY *newentry = (GISTENTRY *) PG_GETARG_POINTER(1);
float *penalty = (float *) PG_GETARG_POINTER(2);
GISTTYPE *origval = (GISTTYPE *) DatumGetPointer(origentry->key);
GISTTYPE *newval = (GISTTYPE *) DatumGetPointer(newentry->key);
int siglen = GET_SIGLEN();
*penalty = hemdist(origval, newval, siglen);
PG_RETURN_POINTER(penalty);
}
typedef struct
{
OffsetNumber pos;
int32 cost;
} SPLITCOST;
static int
comparecost(const void *a, const void *b)
{
return ((const SPLITCOST *) a)->cost - ((const SPLITCOST *) b)->cost;
}
Datum
g_intbig_picksplit(PG_FUNCTION_ARGS)
{
GistEntryVector *entryvec = (GistEntryVector *) PG_GETARG_POINTER(0);
GIST_SPLITVEC *v = (GIST_SPLITVEC *) PG_GETARG_POINTER(1);
int siglen = GET_SIGLEN();
OffsetNumber k,
j;
GISTTYPE *datum_l,
*datum_r;
BITVECP union_l,
union_r;
int32 size_alpha,
size_beta;
int32 size_waste,
waste = -1;
int32 nbytes;
OffsetNumber seed_1 = 0,
seed_2 = 0;
OffsetNumber *left,
*right;
OffsetNumber maxoff;
BITVECP ptr;
int i;
SPLITCOST *costvector;
GISTTYPE *_k,
*_j;
maxoff = entryvec->n - 2;
nbytes = (maxoff + 2) * sizeof(OffsetNumber);
v->spl_left = (OffsetNumber *) palloc(nbytes);
v->spl_right = (OffsetNumber *) palloc(nbytes);
for (k = FirstOffsetNumber; k < maxoff; k = OffsetNumberNext(k))
{
_k = GETENTRY(entryvec, k);
for (j = OffsetNumberNext(k); j <= maxoff; j = OffsetNumberNext(j))
{
size_waste = hemdist(_k, GETENTRY(entryvec, j), siglen);
if (size_waste > waste)
{
waste = size_waste;
seed_1 = k;
seed_2 = j;
}
}
}
left = v->spl_left;
v->spl_nleft = 0;
right = v->spl_right;
v->spl_nright = 0;
if (seed_1 == 0 || seed_2 == 0)
{
seed_1 = 1;
seed_2 = 2;
}
/* form initial .. */
datum_l = _intbig_alloc(ISALLTRUE(GETENTRY(entryvec, seed_1)), siglen,
GETSIGN(GETENTRY(entryvec, seed_1)));
datum_r = _intbig_alloc(ISALLTRUE(GETENTRY(entryvec, seed_2)), siglen,
GETSIGN(GETENTRY(entryvec, seed_2)));
maxoff = OffsetNumberNext(maxoff);
/* sort before ... */
costvector = (SPLITCOST *) palloc(sizeof(SPLITCOST) * maxoff);
for (j = FirstOffsetNumber; j <= maxoff; j = OffsetNumberNext(j))
{
costvector[j - 1].pos = j;
_j = GETENTRY(entryvec, j);
size_alpha = hemdist(datum_l, _j, siglen);
size_beta = hemdist(datum_r, _j, siglen);
costvector[j - 1].cost = abs(size_alpha - size_beta);
}
qsort(costvector, maxoff, sizeof(SPLITCOST), comparecost);
union_l = GETSIGN(datum_l);
union_r = GETSIGN(datum_r);
for (k = 0; k < maxoff; k++)
{
j = costvector[k].pos;
if (j == seed_1)
{
*left++ = j;
v->spl_nleft++;
continue;
}
else if (j == seed_2)
{
*right++ = j;
v->spl_nright++;
continue;
}
_j = GETENTRY(entryvec, j);
size_alpha = hemdist(datum_l, _j, siglen);
size_beta = hemdist(datum_r, _j, siglen);
if (size_alpha < size_beta + WISH_F(v->spl_nleft, v->spl_nright, 0.00001))
{
if (ISALLTRUE(datum_l) || ISALLTRUE(_j))
{
if (!ISALLTRUE(datum_l))
memset(union_l, 0xff, siglen);
}
else
{
ptr = GETSIGN(_j);
LOOPBYTE(siglen)
union_l[i] |= ptr[i];
}
*left++ = j;
v->spl_nleft++;
}
else
{
if (ISALLTRUE(datum_r) || ISALLTRUE(_j))
{
if (!ISALLTRUE(datum_r))
memset(union_r, 0xff, siglen);
}
else
{
ptr = GETSIGN(_j);
LOOPBYTE(siglen)
union_r[i] |= ptr[i];
}
*right++ = j;
v->spl_nright++;
}
}
*right = *left = FirstOffsetNumber;
pfree(costvector);
v->spl_ldatum = PointerGetDatum(datum_l);
v->spl_rdatum = PointerGetDatum(datum_r);
PG_RETURN_POINTER(v);
}
Datum
g_intbig_consistent(PG_FUNCTION_ARGS)
{
GISTENTRY *entry = (GISTENTRY *) PG_GETARG_POINTER(0);
ArrayType *query = PG_GETARG_ARRAYTYPE_P(1);
StrategyNumber strategy = (StrategyNumber) PG_GETARG_UINT16(2);
/* Oid subtype = PG_GETARG_OID(3); */
bool *recheck = (bool *) PG_GETARG_POINTER(4);
int siglen = GET_SIGLEN();
bool retval;
/* All cases served by this function are inexact */
*recheck = true;
if (ISALLTRUE(DatumGetPointer(entry->key)))
PG_RETURN_BOOL(true);
if (strategy == BooleanSearchStrategy)
{
retval = signconsistent((QUERYTYPE *) query,
GETSIGN(DatumGetPointer(entry->key)),
siglen,
false);
PG_FREE_IF_COPY(query, 1);
PG_RETURN_BOOL(retval);
}
CHECKARRVALID(query);
switch (strategy)
{
case RTOverlapStrategyNumber:
retval = _intbig_overlap((GISTTYPE *) DatumGetPointer(entry->key),
query, siglen);
break;
case RTSameStrategyNumber:
if (GIST_LEAF(entry))
{
int i,
num = ARRNELEMS(query);
int32 *ptr = ARRPTR(query);
BITVECP dq = palloc0(siglen),
de;
while (num--)
{
HASH(dq, *ptr, siglen);
ptr++;
}
de = GETSIGN((GISTTYPE *) DatumGetPointer(entry->key));
retval = true;
LOOPBYTE(siglen)
{
if (de[i] != dq[i])
{
retval = false;
break;
}
}
pfree(dq);
}
else
retval = _intbig_contains((GISTTYPE *) DatumGetPointer(entry->key),
query, siglen);
break;
case RTContainsStrategyNumber:
case RTOldContainsStrategyNumber:
retval = _intbig_contains((GISTTYPE *) DatumGetPointer(entry->key),
query, siglen);
break;
case RTContainedByStrategyNumber:
case RTOldContainedByStrategyNumber:
/*
* This code is unreachable as of intarray 1.4, because the <@
* operator has been removed from the opclass. We keep it for now
* to support older versions of the SQL definitions.
*/
if (GIST_LEAF(entry))
{
int i,
num = ARRNELEMS(query);
int32 *ptr = ARRPTR(query);
BITVECP dq = palloc0(siglen),
de;
while (num--)
{
HASH(dq, *ptr, siglen);
ptr++;
}
de = GETSIGN((GISTTYPE *) DatumGetPointer(entry->key));
retval = true;
LOOPBYTE(siglen)
{
if (de[i] & ~dq[i])
{
retval = false;
break;
}
}
}
else
{
/*
* Unfortunately, because empty arrays could be anywhere in
* the index, we must search the whole tree.
*/
retval = true;
}
break;
default:
retval = false;
}
PG_FREE_IF_COPY(query, 1);
PG_RETURN_BOOL(retval);
}
Datum
g_intbig_options(PG_FUNCTION_ARGS)
{
local_relopts *relopts = (local_relopts *) PG_GETARG_POINTER(0);
init_local_reloptions(relopts, sizeof(GISTIntArrayBigOptions));
add_local_int_reloption(relopts, "siglen",
"signature length in bytes",
SIGLEN_DEFAULT, 1, SIGLEN_MAX,
offsetof(GISTIntArrayBigOptions, siglen));
PG_RETURN_VOID();
}
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