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[subset] Optimize set iteration by caching the last found page map index.

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Reuse it if possible on consecutive calls to next(). Will signifcantly speed up cases where the entire set is iterated. In local testing iterating a very large set was 10x faster.
This commit is contained in:
Garret Rieger 2021-05-20 16:22:04 -07:00 committed by Behdad Esfahbod
parent 1bb00cd54b
commit 2c137045dc
1 changed files with 28 additions and 9 deletions
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37
src/hb-set.hh
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@ -220,6 +220,7 @@ struct hb_set_t
hb_object_header_t header;
bool successful; /* Allocations successful */
mutable unsigned int population;
mutable unsigned int last_page_lookup;
hb_sorted_vector_t<page_map_t> page_map;
hb_vector_t<page_t> pages;
@ -227,6 +228,7 @@ struct hb_set_t
{
successful = true;
population = 0;
last_page_lookup = 0;
page_map.init ();
pages.init ();
}
@ -238,6 +240,7 @@ struct hb_set_t
void fini_shallow ()
{
population = 0;
last_page_lookup = 0;
page_map.fini ();
pages.fini ();
}
@ -742,27 +745,43 @@ struct hb_set_t
return *codepoint != INVALID;
}
page_map_t map = {get_major (*codepoint), 0};
unsigned int i;
page_map.bfind (map, &i, HB_BFIND_NOT_FOUND_STORE_CLOSEST);
if (i < page_map.length && page_map[i].major == map.major)
unsigned int major = get_major (*codepoint);
unsigned int i = last_page_lookup;
if (unlikely (i >= page_map.length || (page_map.arrayZ[i]).major != major))
{
if (pages[page_map[i].index].next (codepoint))
page_map_t map = {major, 0};
page_map.bfind (map, &i, HB_BFIND_NOT_FOUND_STORE_CLOSEST);
if (i >= page_map.length) {
*codepoint = INVALID;
return false;
}
}
page_map_t &current = page_map.arrayZ[i];
if (likely (current.major == major))
{
if (pages.arrayZ[current.index].next (codepoint))
{
*codepoint += page_map[i].major * page_t::PAGE_BITS;
return true;
*codepoint += current.major * page_t::PAGE_BITS;
last_page_lookup = i;
return true;
}
i++;
}
for (; i < page_map.length; i++)
{
hb_codepoint_t m = pages[page_map[i].index].get_min ();
const page_map_t &current = page_map.arrayZ[i];
hb_codepoint_t m = pages.arrayZ[current.index].get_min ();
if (m != INVALID)
{
*codepoint = page_map[i].major * page_t::PAGE_BITS + m;
*codepoint = current.major * page_t::PAGE_BITS + m;
last_page_lookup = i;
return true;
}
}
last_page_lookup = 0;
*codepoint = INVALID;
return false;
}