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Codechange: Sort EngineOverrideManager for fast lookups.

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Allows quickly finding the EngineID given the type, grfid and local id of an engine, instead a linear scan.

This can reduce loading time when lots of engines are present and also affects performance in-game.
Lookup can be on the order of 10000 times faster.
This commit is contained in:
Peter Nelson
2024-11-21 22:05:08 +00:00
committed by Peter Nelson
parent 01d1ea6264
commit f56b6756f1
5 changed files with 112 additions and 59 deletions
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32
src/saveload/engine_sl.cpp
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@@ -189,11 +189,25 @@ struct EIDSChunkHandler : ChunkHandler {
{
SlTableHeader(_engine_id_mapping_desc);
uint index = 0;
for (EngineIDMapping &eid : _engine_mngr.mappings) {
SlSetArrayIndex(index);
/* Count total entries needed for combined list. */
size_t total = 0;
for (const auto &mapping : _engine_mngr.mappings) {
total += std::size(mapping);
}
/* Combine per-type mappings into single list for all types. */
std::vector<EngineIDMapping> temp;
temp.reserve(total);
for (const auto &mapping : _engine_mngr.mappings) {
temp.insert(std::end(temp), std::begin(mapping), std::end(mapping));
}
/* Sort combined list by EngineID */
std::ranges::sort(temp, std::less{}, &EngineIDMapping::engine);
for (EngineIDMapping &eid : temp) {
SlSetArrayIndex(eid.engine);
SlObject(&eid, _engine_id_mapping_desc);
index++;
}
}
@@ -201,11 +215,13 @@ struct EIDSChunkHandler : ChunkHandler {
{
const std::vector<SaveLoad> slt = SlCompatTableHeader(_engine_id_mapping_desc, _engine_id_mapping_sl_compat);
_engine_mngr.mappings.clear();
_engine_mngr.mappings = {};
while (SlIterateArray() != -1) {
EngineIDMapping *eid = &_engine_mngr.mappings.emplace_back();
SlObject(eid, slt);
int index;
while ((index = SlIterateArray()) != -1) {
EngineIDMapping eid;
SlObject(&eid, slt);
_engine_mngr.SetID(eid.type, eid.internal_id, eid.grfid, eid.substitute_id, index);
}
}
};