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Remove bms_first_member().

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This function has been semi-deprecated ever since we invented
bms_next_member().  Its habit of scribbling on the input bitmapset
isn't great, plus for sufficiently large bitmapsets it would take
O(N^2) time to complete a loop.  Now we have the additional problem
that reducing the input to empty while leaving it still accessible
would violate a planned invariant.  So let's just get rid of it,
after updating the few extant callers to use bms_next_member().

Patch by me; thanks to Nathan Bossart and Richard Guo for review.

Discussion: https://postgr.es/m/1159933.1677621588@sss.pgh.pa.us
This commit is contained in:
Tom Lane
2023-03-02 11:34:29 -05:00
parent 2f80c95740
commit 462bb7f128
9 changed files with 23 additions and 70 deletions
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42
src/backend/nodes/bitmapset.c
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@@ -982,48 +982,6 @@ bms_join(Bitmapset *a, Bitmapset *b)
return result;
}
/*
* bms_first_member - find and remove first member of a set
*
* Returns -1 if set is empty. NB: set is destructively modified!
*
* This is intended as support for iterating through the members of a set.
* The typical pattern is
*
* while ((x = bms_first_member(inputset)) >= 0)
* process member x;
*
* CAUTION: this destroys the content of "inputset". If the set must
* not be modified, use bms_next_member instead.
*/
int
bms_first_member(Bitmapset *a)
{
int nwords;
int wordnum;
if (a == NULL)
return -1;
nwords = a->nwords;
for (wordnum = 0; wordnum < nwords; wordnum++)
{
bitmapword w = a->words[wordnum];
if (w != 0)
{
int result;
w = RIGHTMOST_ONE(w);
a->words[wordnum] &= ~w;
result = wordnum * BITS_PER_BITMAPWORD;
result += bmw_rightmost_one_pos(w);
return result;
}
}
return -1;
}
/*
* bms_next_member - find next member of a set
*