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Performance Improvement: Use a cache which caches result for getFaceP…
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…ositions.

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
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@nerzhul
nerzhul committed Feb 16, 2015
1 parent ed04e8e commit 7c8793c
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Showing 4 changed files with 81 additions and 68 deletions.
13 changes: 5 additions & 8 deletions src/clientiface.cpp
View file
Expand Up @@ -59,7 +59,7 @@ void RemoteClient::ResendBlockIfOnWire(v3s16 p)
}
}

void RemoteClient::GetNextBlocks(
void RemoteClient::GetNextBlocks (
ServerEnvironment *env,
EmergeManager * emerge,
float dtime,
Expand Down Expand Up @@ -182,18 +182,15 @@ void RemoteClient::GetNextBlocks(
//bool queue_is_full = false;

s16 d;
for(d = d_start; d <= d_max; d++)
{
for(d = d_start; d <= d_max; d++) {
/*
Get the border/face dot coordinates of a "d-radiused"
box
*/
std::list<v3s16> list;
getFacePositions(list, d);
std::vector<v3s16> list = FacePositionCache::getFacePositions(d);

std::list<v3s16>::iterator li;
for(li=list.begin(); li!=list.end(); ++li)
{
std::vector<v3s16>::iterator li;
for(li = list.begin(); li != list.end(); ++li) {
v3s16 p = *li + center;

/*
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5 changes: 2 additions & 3 deletions src/script/lua_api/l_env.cpp
View file
Expand Up @@ -530,9 +530,8 @@ int ModApiEnvMod::l_find_node_near(lua_State *L)
}

for(int d=1; d<=radius; d++){
std::list<v3s16> list;
getFacePositions(list, d);
for(std::list<v3s16>::iterator i = list.begin();
std::vector<v3s16> list = FacePositionCache::getFacePositions(d);
for(std::vector<v3s16>::iterator i = list.begin();
i != list.end(); ++i){
v3s16 p = pos + (*i);
content_t c = env->getMap().getNodeNoEx(p).getContent();
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114 changes: 59 additions & 55 deletions src/util/numeric.cpp
View file
Expand Up @@ -20,90 +20,94 @@ 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));
}
}
}

// 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));
}
}

Expand Down
17 changes: 15 additions & 2 deletions src/util/numeric.h
View file
Expand Up @@ -25,10 +25,23 @@ with this program; if not, write to the Free Software Foundation, Inc.,
#include "../irr_v3d.h"
#include "../irr_aabb3d.h"
#include <list>
#include <map>
#include <vector>
#include <algorithm>

// Calculate the borders of a "d-radius" cube
void getFacePositions(std::list<v3s16> &list, u16 d);

/*
* This class permits to cache getFacePosition call results
* This reduces CPU usage and vector calls
*/
class FacePositionCache
{
public:
static std::vector<v3s16> getFacePositions(u16 d);
private:
static void generateFacePosition(u16 d);
static std::map<u16, std::vector<v3s16> > m_cache;
};

class IndentationRaiser
{
Expand Down

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