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

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;
}