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Modify various power 2 calculations to use new helper functions

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First pass of modifying various places that obtain the next power of 2 of
a number and make them use the new functions added in pg_bitutils.h
instead.

This also removes the _hash_log2() function. There are no longer any
callers in core. Other users can swap their _hash_log2(n) call to make use
of pg_ceil_log2_32(n).

Author: David Fetter, with some minor adjustments by me
Reviewed-by: John Naylor, Jesse Zhang
Discussion: https://postgr.es/m/20200114173553.GE32763%40fetter.org
This commit is contained in:
David Rowley
2020-04-08 16:55:03 +12:00
parent 50a38f6517
commit d025cf88ba
7 changed files with 32 additions and 62 deletions
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27
src/include/lib/simplehash.h
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@@ -57,6 +57,8 @@
* backwards, unless they're empty or already at their optimal position.
*/
#include "port/pg_bitutils.h"
/* helpers */
#define SH_MAKE_PREFIX(a) CppConcat(a,_)
#define SH_MAKE_NAME(name) SH_MAKE_NAME_(SH_MAKE_PREFIX(SH_PREFIX),name)
@@ -215,27 +217,6 @@ SH_SCOPE void SH_STAT(SH_TYPE * tb);
#ifndef SIMPLEHASH_H
#define SIMPLEHASH_H
/* FIXME: can we move these to a central location? */
/* calculate ceil(log base 2) of num */
static inline uint64
sh_log2(uint64 num)
{
int i;
uint64 limit;
for (i = 0, limit = 1; limit < num; i++, limit <<= 1)
;
return i;
}
/* calculate first power of 2 >= num */
static inline uint64
sh_pow2(uint64 num)
{
return ((uint64) 1) << sh_log2(num);
}
#ifdef FRONTEND
#define sh_error(...) pg_log_error(__VA_ARGS__)
#define sh_log(...) pg_log_info(__VA_ARGS__)
@@ -259,7 +240,7 @@ SH_COMPUTE_PARAMETERS(SH_TYPE * tb, uint32 newsize)
size = Max(newsize, 2);
/* round up size to the next power of 2, that's how bucketing works */
size = sh_pow2(size);
size = pg_nextpower2_64(size);
Assert(size <= SH_MAX_SIZE);
/*
@@ -434,7 +415,7 @@ SH_GROW(SH_TYPE * tb, uint32 newsize)
uint32 startelem = 0;
uint32 copyelem;
Assert(oldsize == sh_pow2(oldsize));
Assert(oldsize == pg_nextpower2_64(oldsize));
Assert(oldsize != SH_MAX_SIZE);
Assert(oldsize < newsize);