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Performance Improvement: Use a cache which caches result for getFacePositions.

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This greatly reduce the number of std::list generated by caching the result, which is always constant for each radius selected.
In the callgrind map, you will see original:
  * 3.3M calls to std::list for 9700 calls to getFacePositions
In the modified version, you will see:
  * 3.3K calls to std::list for 6900 call to getFacePositions
Callgrind map is here: #2321

it's a huge performance improvement to l_find_node_near
This commit is contained in:
Loic Blot 2015-02-15 17:30:38 +01:00
parent ed04e8e9e4
commit 7c8793cbea
4 changed files with 81 additions and 68 deletions
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114
src/util/numeric.cpp
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@ -20,79 +20,84 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#include "numeric.h"
#include "mathconstants.h"
#include "../log.h"
#include "log.h"
#include "../constants.h" // BS, MAP_BLOCKSIZE
#include <string.h>
#include <iostream>
std::map<u16, std::vector<v3s16> > FacePositionCache::m_cache;
// Calculate the borders of a "d-radius" cube
void getFacePositions(std::list<v3s16> &list, u16 d)
std::vector<v3s16> FacePositionCache::getFacePositions(u16 d)
{
if(d == 0)
{
list.push_back(v3s16(0,0,0));
if (m_cache.find(d) != m_cache.end())
return m_cache[d];
generateFacePosition(d);
return m_cache[d];
}
void FacePositionCache::generateFacePosition(u16 d)
{
m_cache[d] = std::vector<v3s16>();
if(d == 0) {
m_cache[d].push_back(v3s16(0,0,0));
return;
}
if(d == 1)
{
if(d == 1) {
/*
This is an optimized sequence of coordinates.
*/
list.push_back(v3s16( 0, 1, 0)); // top
list.push_back(v3s16( 0, 0, 1)); // back
list.push_back(v3s16(-1, 0, 0)); // left
list.push_back(v3s16( 1, 0, 0)); // right
list.push_back(v3s16( 0, 0,-1)); // front
list.push_back(v3s16( 0,-1, 0)); // bottom
m_cache[d].push_back(v3s16( 0, 1, 0)); // top
m_cache[d].push_back(v3s16( 0, 0, 1)); // back
m_cache[d].push_back(v3s16(-1, 0, 0)); // left
m_cache[d].push_back(v3s16( 1, 0, 0)); // right
m_cache[d].push_back(v3s16( 0, 0,-1)); // front
m_cache[d].push_back(v3s16( 0,-1, 0)); // bottom
// 6
list.push_back(v3s16(-1, 0, 1)); // back left
list.push_back(v3s16( 1, 0, 1)); // back right
list.push_back(v3s16(-1, 0,-1)); // front left
list.push_back(v3s16( 1, 0,-1)); // front right
list.push_back(v3s16(-1,-1, 0)); // bottom left
list.push_back(v3s16( 1,-1, 0)); // bottom right
list.push_back(v3s16( 0,-1, 1)); // bottom back
list.push_back(v3s16( 0,-1,-1)); // bottom front
list.push_back(v3s16(-1, 1, 0)); // top left
list.push_back(v3s16( 1, 1, 0)); // top right
list.push_back(v3s16( 0, 1, 1)); // top back
list.push_back(v3s16( 0, 1,-1)); // top front
m_cache[d].push_back(v3s16(-1, 0, 1)); // back left
m_cache[d].push_back(v3s16( 1, 0, 1)); // back right
m_cache[d].push_back(v3s16(-1, 0,-1)); // front left
m_cache[d].push_back(v3s16( 1, 0,-1)); // front right
m_cache[d].push_back(v3s16(-1,-1, 0)); // bottom left
m_cache[d].push_back(v3s16( 1,-1, 0)); // bottom right
m_cache[d].push_back(v3s16( 0,-1, 1)); // bottom back
m_cache[d].push_back(v3s16( 0,-1,-1)); // bottom front
m_cache[d].push_back(v3s16(-1, 1, 0)); // top left
m_cache[d].push_back(v3s16( 1, 1, 0)); // top right
m_cache[d].push_back(v3s16( 0, 1, 1)); // top back
m_cache[d].push_back(v3s16( 0, 1,-1)); // top front
// 18
list.push_back(v3s16(-1, 1, 1)); // top back-left
list.push_back(v3s16( 1, 1, 1)); // top back-right
list.push_back(v3s16(-1, 1,-1)); // top front-left
list.push_back(v3s16( 1, 1,-1)); // top front-right
list.push_back(v3s16(-1,-1, 1)); // bottom back-left
list.push_back(v3s16( 1,-1, 1)); // bottom back-right
list.push_back(v3s16(-1,-1,-1)); // bottom front-left
list.push_back(v3s16( 1,-1,-1)); // bottom front-right
m_cache[d].push_back(v3s16(-1, 1, 1)); // top back-left
m_cache[d].push_back(v3s16( 1, 1, 1)); // top back-right
m_cache[d].push_back(v3s16(-1, 1,-1)); // top front-left
m_cache[d].push_back(v3s16( 1, 1,-1)); // top front-right
m_cache[d].push_back(v3s16(-1,-1, 1)); // bottom back-left
m_cache[d].push_back(v3s16( 1,-1, 1)); // bottom back-right
m_cache[d].push_back(v3s16(-1,-1,-1)); // bottom front-left
m_cache[d].push_back(v3s16( 1,-1,-1)); // bottom front-right
// 26
return;
}
// Take blocks in all sides, starting from y=0 and going +-y
for(s16 y=0; y<=d-1; y++)
{
for(s16 y=0; y<=d-1; y++) {
// Left and right side, including borders
for(s16 z=-d; z<=d; z++)
{
list.push_back(v3s16(d,y,z));
list.push_back(v3s16(-d,y,z));
if(y != 0)
{
list.push_back(v3s16(d,-y,z));
list.push_back(v3s16(-d,-y,z));
for(s16 z=-d; z<=d; z++) {
m_cache[d].push_back(v3s16(d,y,z));
m_cache[d].push_back(v3s16(-d,y,z));
if(y != 0) {
m_cache[d].push_back(v3s16(d,-y,z));
m_cache[d].push_back(v3s16(-d,-y,z));
}
}
// Back and front side, excluding borders
for(s16 x=-d+1; x<=d-1; x++)
{
list.push_back(v3s16(x,y,d));
list.push_back(v3s16(x,y,-d));
if(y != 0)
{
list.push_back(v3s16(x,-y,d));
list.push_back(v3s16(x,-y,-d));
for(s16 x=-d+1; x<=d-1; x++) {
m_cache[d].push_back(v3s16(x,y,d));
m_cache[d].push_back(v3s16(x,y,-d));
if(y != 0) {
m_cache[d].push_back(v3s16(x,-y,d));
m_cache[d].push_back(v3s16(x,-y,-d));
}
}
}
@ -100,10 +105,9 @@ void getFacePositions(std::list<v3s16> &list, u16 d)
// Take the bottom and top face with borders
// -d<x<d, y=+-d, -d<z<d
for(s16 x=-d; x<=d; x++)
for(s16 z=-d; z<=d; z++)
{
list.push_back(v3s16(x,-d,z));
list.push_back(v3s16(x,d,z));
for(s16 z=-d; z<=d; z++) {
m_cache[d].push_back(v3s16(x,-d,z));
m_cache[d].push_back(v3s16(x,d,z));
}
}