mongo-debian/db/geo/core.h
2011-09-14 17:08:06 +02:00

520 lines
15 KiB
C++

// core.h
/**
* Copyright (C) 2008 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include "../../pch.h"
#include "../jsobj.h"
#include <cmath>
#ifndef M_PI
# define M_PI 3.14159265358979323846
#endif
namespace mongo {
class GeoBitSets {
public:
GeoBitSets() {
for ( int i=0; i<32; i++ ) {
masks32[i] = ( 1 << ( 31 - i ) );
}
for ( int i=0; i<64; i++ ) {
masks64[i] = ( 1LL << ( 63 - i ) );
}
for ( unsigned i=0; i<16; i++ ) {
unsigned fixed = 0;
for ( int j=0; j<4; j++ ) {
if ( i & ( 1 << j ) )
fixed |= ( 1 << ( j * 2 ) );
}
hashedToNormal[fixed] = i;
}
}
int masks32[32];
long long masks64[64];
unsigned hashedToNormal[256];
};
extern GeoBitSets geoBitSets;
class GeoHash {
public:
GeoHash()
: _hash(0),_bits(0) {
}
explicit GeoHash( const char * hash ) {
init( hash );
}
explicit GeoHash( const string& hash ) {
init( hash );
}
static GeoHash makeFromBinData(const char *bindata, unsigned bits) {
GeoHash h;
h._bits = bits;
h._copy( (char*)&h._hash , bindata );
h._fix();
return h;
}
explicit GeoHash( const BSONElement& e , unsigned bits=32 ) {
_bits = bits;
if ( e.type() == BinData ) {
int len = 0;
_copy( (char*)&_hash , e.binData( len ) );
assert( len == 8 );
_bits = bits;
}
else {
cout << "GeoHash bad element: " << e << endl;
uassert(13047,"wrong type for geo index. if you're using a pre-release version, need to rebuild index",0);
}
_fix();
}
GeoHash( unsigned x , unsigned y , unsigned bits=32) {
init( x , y , bits );
}
GeoHash( const GeoHash& old ) {
_hash = old._hash;
_bits = old._bits;
}
GeoHash( long long hash , unsigned bits )
: _hash( hash ) , _bits( bits ) {
_fix();
}
void init( unsigned x , unsigned y , unsigned bits ) {
assert( bits <= 32 );
_hash = 0;
_bits = bits;
for ( unsigned i=0; i<bits; i++ ) {
if ( isBitSet( x , i ) ) _hash |= geoBitSets.masks64[i*2];
if ( isBitSet( y , i ) ) _hash |= geoBitSets.masks64[(i*2)+1];
}
}
void unhash_fast( unsigned& x , unsigned& y ) const {
x = 0;
y = 0;
char * c = (char*)(&_hash);
for ( int i=0; i<8; i++ ) {
unsigned t = (unsigned)(c[i]) & 0x55;
y |= ( geoBitSets.hashedToNormal[t] << (4*(i)) );
t = ( (unsigned)(c[i]) >> 1 ) & 0x55;
x |= ( geoBitSets.hashedToNormal[t] << (4*(i)) );
}
}
void unhash_slow( unsigned& x , unsigned& y ) const {
x = 0;
y = 0;
for ( unsigned i=0; i<_bits; i++ ) {
if ( getBitX(i) )
x |= geoBitSets.masks32[i];
if ( getBitY(i) )
y |= geoBitSets.masks32[i];
}
}
void unhash( unsigned& x , unsigned& y ) const {
unhash_fast( x , y );
}
/**
* @param 0 = high
*/
static bool isBitSet( unsigned val , unsigned bit ) {
return geoBitSets.masks32[bit] & val;
}
GeoHash up() const {
return GeoHash( _hash , _bits - 1 );
}
bool hasPrefix( const GeoHash& other ) const {
assert( other._bits <= _bits );
if ( other._bits == 0 )
return true;
long long x = other._hash ^ _hash;
x = x >> (64-(other._bits*2));
return x == 0;
}
string toString() const {
StringBuilder buf( _bits * 2 );
for ( unsigned x=0; x<_bits*2; x++ )
buf.append( _hash & geoBitSets.masks64[x] ? "1" : "0" );
return buf.str();
}
string toStringHex1() const {
stringstream ss;
ss << hex << _hash;
return ss.str();
}
void init( const string& s ) {
_hash = 0;
_bits = s.size() / 2;
for ( unsigned pos=0; pos<s.size(); pos++ )
if ( s[pos] == '1' )
setBit( pos , 1 );
}
void setBit( unsigned pos , bool one ) {
assert( pos < _bits * 2 );
if ( one )
_hash |= geoBitSets.masks64[pos];
else if ( _hash & geoBitSets.masks64[pos] )
_hash &= ~geoBitSets.masks64[pos];
}
bool getBit( unsigned pos ) const {
return _hash & geoBitSets.masks64[pos];
}
bool getBitX( unsigned pos ) const {
assert( pos < 32 );
return getBit( pos * 2 );
}
bool getBitY( unsigned pos ) const {
assert( pos < 32 );
return getBit( ( pos * 2 ) + 1 );
}
BSONObj wrap() const {
BSONObjBuilder b(20);
append( b , "" );
BSONObj o = b.obj();
assert( o.objsize() == 20 );
return o;
}
bool constrains() const {
return _bits > 0;
}
bool canRefine() const {
return _bits < 32;
}
void move( int x , int y ) {
assert( _bits );
_move( 0 , x );
_move( 1 , y );
}
void _move( unsigned offset , int d ) {
if ( d == 0 )
return;
assert( d <= 1 && d>= -1 ); // TEMP
bool from, to;
if ( d > 0 ) {
from = 0;
to = 1;
}
else {
from = 1;
to = 0;
}
unsigned pos = ( _bits * 2 ) - 1;
if ( offset == 0 )
pos--;
while ( true ) {
if ( getBit(pos) == from ) {
setBit( pos , to );
return;
}
if ( pos < 2 ) {
// overflow
for ( ; pos < ( _bits * 2 ) ; pos += 2 ) {
setBit( pos , from );
}
return;
}
setBit( pos , from );
pos -= 2;
}
assert(0);
}
GeoHash& operator=(const GeoHash& h) {
_hash = h._hash;
_bits = h._bits;
return *this;
}
bool operator==(const GeoHash& h ) const {
return _hash == h._hash && _bits == h._bits;
}
bool operator!=(const GeoHash& h ) const {
return !( *this == h );
}
bool operator<(const GeoHash& h ) const {
if( _hash != h._hash ) return _hash < h._hash;
return _bits < h._bits;
}
GeoHash& operator+=( const char * s ) {
unsigned pos = _bits * 2;
_bits += strlen(s) / 2;
assert( _bits <= 32 );
while ( s[0] ) {
if ( s[0] == '1' )
setBit( pos , 1 );
pos++;
s++;
}
return *this;
}
GeoHash operator+( const char * s ) const {
GeoHash n = *this;
n+=s;
return n;
}
GeoHash operator+( string s ) const {
return operator+( s.c_str() );
}
void _fix() {
static long long FULL = 0xFFFFFFFFFFFFFFFFLL;
long long mask = FULL << ( 64 - ( _bits * 2 ) );
_hash &= mask;
}
void append( BSONObjBuilder& b , const char * name ) const {
char buf[8];
_copy( buf , (char*)&_hash );
b.appendBinData( name , 8 , bdtCustom , buf );
}
long long getHash() const {
return _hash;
}
unsigned getBits() const {
return _bits;
}
GeoHash commonPrefix( const GeoHash& other ) const {
unsigned i=0;
for ( ; i<_bits && i<other._bits; i++ ) {
if ( getBitX( i ) == other.getBitX( i ) &&
getBitY( i ) == other.getBitY( i ) )
continue;
break;
}
return GeoHash(_hash,i);
}
private:
static void _copy( char * dst , const char * src ) {
for ( unsigned a=0; a<8; a++ ) {
dst[a] = src[7-a];
}
}
long long _hash;
unsigned _bits; // bits per field, so 1 to 32
};
inline ostream& operator<<( ostream &s, const GeoHash &h ) {
s << h.toString();
return s;
}
class GeoConvert {
public:
virtual ~GeoConvert() {}
virtual void unhash( const GeoHash& h , double& x , double& y ) const = 0;
virtual GeoHash hash( double x , double y ) const = 0;
};
class Point {
public:
Point( const GeoConvert * g , const GeoHash& hash ) {
g->unhash( hash , _x , _y );
}
explicit Point( const BSONElement& e ) {
BSONObjIterator i(e.Obj());
_x = i.next().number();
_y = i.next().number();
}
explicit Point( const BSONObj& o ) {
BSONObjIterator i(o);
_x = i.next().number();
_y = i.next().number();
}
Point( double x , double y )
: _x( x ) , _y( y ) {
}
Point() : _x(0),_y(0) {
}
GeoHash hash( const GeoConvert * g ) {
return g->hash( _x , _y );
}
double distance( const Point& p ) const {
double a = _x - p._x;
double b = _y - p._y;
// Avoid numerical error if possible...
if( a == 0 ) return abs( _y - p._y );
if( b == 0 ) return abs( _x - p._x );
return sqrt( ( a * a ) + ( b * b ) );
}
/**
* Distance method that compares x or y coords when other direction is zero,
* avoids numerical error when distances are very close to radius but axis-aligned.
*
* An example of the problem is:
* (52.0 - 51.9999) - 0.0001 = 3.31965e-15 and 52.0 - 51.9999 > 0.0001 in double arithmetic
* but:
* 51.9999 + 0.0001 <= 52.0
*
* This avoids some (but not all!) suprising results in $center queries where points are
* ( radius + center.x, center.y ) or vice-versa.
*/
bool distanceWithin( const Point& p, double radius ) const {
double a = _x - p._x;
double b = _y - p._y;
if( a == 0 ) {
//
// Note: For some, unknown reason, when a 32-bit g++ optimizes this call, the sum is
// calculated imprecisely. We need to force the compiler to always evaluate it correctly,
// hence the weirdness.
//
// On some 32-bit linux machines, removing the volatile keyword or calculating the sum inline
// will make certain geo tests fail. Of course this check will force volatile for all 32-bit systems,
// not just affected systems.
if( sizeof(void*) <= 4 ){
volatile double sum = _y > p._y ? p._y + radius : _y + radius;
return _y > p._y ? sum >= _y : sum >= p._y;
}
else {
// Original math, correct for most systems
return _y > p._y ? p._y + radius >= _y : _y + radius >= p._y;
}
}
if( b == 0 ) {
if( sizeof(void*) <= 4 ){
volatile double sum = _x > p._x ? p._x + radius : _x + radius;
return _x > p._x ? sum >= _x : sum >= p._x;
}
else {
return _x > p._x ? p._x + radius >= _x : _x + radius >= p._x;
}
}
return sqrt( ( a * a ) + ( b * b ) ) <= radius;
}
string toString() const {
StringBuilder buf(32);
buf << "(" << _x << "," << _y << ")";
return buf.str();
}
double _x;
double _y;
};
extern const double EARTH_RADIUS_KM;
extern const double EARTH_RADIUS_MILES;
// Technically lat/long bounds, not really tied to earth radius.
inline void checkEarthBounds( Point p ) {
uassert( 14808, str::stream() << "point " << p.toString() << " must be in earth-like bounds of long : [-180, 180), lat : [-90, 90] ",
p._x >= -180 && p._x < 180 && p._y >= -90 && p._y <= 90 );
}
inline double deg2rad(double deg) { return deg * (M_PI/180); }
inline double rad2deg(double rad) { return rad * (180/M_PI); }
// WARNING: _x and _y MUST be longitude and latitude in that order
// note: multiply by earth radius for distance
inline double spheredist_rad( const Point& p1, const Point& p2 ) {
// this uses the n-vector formula: http://en.wikipedia.org/wiki/N-vector
// If you try to match the code to the formula, note that I inline the cross-product.
// TODO: optimize with SSE
double sin_x1(sin(p1._x)), cos_x1(cos(p1._x));
double sin_y1(sin(p1._y)), cos_y1(cos(p1._y));
double sin_x2(sin(p2._x)), cos_x2(cos(p2._x));
double sin_y2(sin(p2._y)), cos_y2(cos(p2._y));
double cross_prod =
(cos_y1*cos_x1 * cos_y2*cos_x2) +
(cos_y1*sin_x1 * cos_y2*sin_x2) +
(sin_y1 * sin_y2);
if (cross_prod >= 1 || cross_prod <= -1) {
// fun with floats
assert( fabs(cross_prod)-1 < 1e-6 );
return cross_prod > 0 ? 0 : M_PI;
}
return acos(cross_prod);
}
// note: return is still in radians as that can be multiplied by radius to get arc length
inline double spheredist_deg( const Point& p1, const Point& p2 ) {
return spheredist_rad(
Point( deg2rad(p1._x), deg2rad(p1._y) ),
Point( deg2rad(p2._x), deg2rad(p2._y) )
);
}
}