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Speedup getBlockNodeIdMapping by up to factor 4 by using a fixed size…

… mapping array
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sapier sapier
sapier authored and sapier committed Jun 8, 2014
1 parent 2625323 commit 5d06bdf8ac3b38b1ffb400fd771a245589d92ad1
Showing with 10 additions and 6 deletions.
  1. +10 −6 src/mapblock.cpp
@@ -452,10 +452,16 @@ s16 MapBlock::getGroundLevel(v2s16 p2d)
*/
// List relevant id-name pairs for ids in the block using nodedef
// Renumbers the content IDs (starting at 0 and incrementing
// use static memory requires about 65535 * sizeof(int) ram in order to be
// sure we can handle all content ids. But it's absolutely worth it as it's
// a speedup of 4 for one of the major time consuming functions on storing
// mapblocks.
static content_t getBlockNodeIdMapping_mapping[USHRT_MAX];
static void getBlockNodeIdMapping(NameIdMapping *nimap, MapNode *nodes,
INodeDefManager *nodedef)
{
std::map<content_t, content_t> mapping;
memset(getBlockNodeIdMapping_mapping, 0xFF, USHRT_MAX * sizeof(content_t));

std::set<content_t> unknown_contents;
content_t id_counter = 0;
for(u32 i=0; i<MAP_BLOCKSIZE*MAP_BLOCKSIZE*MAP_BLOCKSIZE; i++)
@@ -464,16 +470,14 @@ static void getBlockNodeIdMapping(NameIdMapping *nimap, MapNode *nodes,
content_t id = CONTENT_IGNORE;

// Try to find an existing mapping
std::map<content_t, content_t>::iterator j = mapping.find(global_id);
if(j != mapping.end())
{
id = j->second;
if (getBlockNodeIdMapping_mapping[global_id] != 0xFFFF) {
id = getBlockNodeIdMapping_mapping[global_id];
}
else
{
// We have to assign a new mapping
id = id_counter++;
mapping.insert(std::make_pair(global_id, id));
getBlockNodeIdMapping_mapping[global_id] = id;

const ContentFeatures &f = nodedef->get(global_id);
const std::string &name = f.name;

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