GeoSearch::GeoSearch(Collection* collection,
TwoDAccessMethod* accessMethod,
const Point& startPt,
int numWanted,
MatchExpression* filter,
double maxDistance,
GeoDistType type)
: GeoHopper(collection, accessMethod, numWanted, startPt, filter, maxDistance, type),
_start(accessMethod->getParams().geoHashConverter->hash(startPt.x, startPt.y)),
_numWanted(numWanted),
_type(type),
_params(accessMethod->getParams()) {
_nscanned = 0;
_found = 0;
if(_maxDistance < 0){
_scanDistance = numeric_limits<double>::max();
} else if (type == GEO_PLANE) {
_scanDistance = maxDistance + _params.geoHashConverter->getError();
} else if (type == GEO_SPHERE) {
checkEarthBounds(startPt);
// TODO: consider splitting into x and y scan distances
_scanDistance = computeXScanDistance(startPt.y,
rad2deg(_maxDistance) + _params.geoHashConverter->getError());
}
verify(_scanDistance > 0);
}
GeoCircleBrowse::GeoCircleBrowse(const TwoDParams& params, TwoDAccessMethod* accessMethod)
: GeoBrowse(accessMethod, "circle", params.filter, params.gq.uniqueDocs()) {
_converter = accessMethod->getParams().geoHashConverter;
const CapWithCRS& cap = *params.gq.getGeometry()._cap;
_startPt = cap.circle.center;
_start = _converter->hash(_startPt);
_maxDistance = cap.circle.radius;
if (FLAT == cap.crs) {
_type = GEO_PLANE;
xScanDistance = _maxDistance + _converter->getError();
yScanDistance = _maxDistance + _converter->getError();
} else {
_type = GEO_SPHERE;
yScanDistance = rad2deg(_maxDistance) + _converter->getError();
xScanDistance = computeXScanDistance(_startPt.y, yScanDistance);
}
// Bounding box includes fudge factor.
// TODO: Is this correct, since fudge factor may be spherically transformed?
_bBox._min = Point(_startPt.x - xScanDistance, _startPt.y - yScanDistance);
_bBox._max = Point(_startPt.x + xScanDistance, _startPt.y + yScanDistance);
ok();
}
static R2Annulus projectBoundsToTwoDDegrees(R2Annulus sphereBounds) {
const double outerDegrees = rad2deg(sphereBounds.getOuter() / kRadiusOfEarthInMeters);
const double innerDegrees = rad2deg(sphereBounds.getInner() / kRadiusOfEarthInMeters);
const double maxErrorDegrees = computeXScanDistance(sphereBounds.center().y, outerDegrees);
return R2Annulus(sphereBounds.center(),
max(0.0, innerDegrees - maxErrorDegrees),
outerDegrees + maxErrorDegrees);
}
/**
* 2d indices don't handle wrapping so we can't use them for queries that wrap.
*/
static bool twoDWontWrap(const Circle& circle, const IndexEntry& index) {
GeoHashConverter::Parameters hashParams;
Status paramStatus = GeoHashConverter::parseParameters(index.infoObj, &hashParams);
verify(paramStatus.isOK()); // we validated the params on index creation
GeoHashConverter conv(hashParams);
// FYI: old code used flat not spherical error.
double yscandist = rad2deg(circle.radius) + conv.getErrorSphere();
double xscandist = computeXScanDistance(circle.center.y, yscandist);
bool ret = circle.center.x + xscandist < 180
&& circle.center.x - xscandist > -180
&& circle.center.y + yscandist < 90
&& circle.center.y - yscandist > -90;
return ret;
}
/**
* 2d indices don't handle wrapping so we can't use them for queries that wrap.
*/
static bool twoDWontWrap(const Circle& circle, const IndexEntry& index) {
// XXX: where does this really belong
GeoHashConverter::Parameters params;
params.bits = static_cast<unsigned>(fieldWithDefault(index.infoObj, "bits", 26));
params.max = fieldWithDefault(index.infoObj, "max", 180.0);
params.min = fieldWithDefault(index.infoObj, "min", -180.0);
double numBuckets = (1024 * 1024 * 1024 * 4.0);
params.scaling = numBuckets / (params.max - params.min);
GeoHashConverter conv(params);
// FYI: old code used flat not spherical error.
double yscandist = rad2deg(circle.radius) + conv.getErrorSphere();
double xscandist = computeXScanDistance(circle.center.y, yscandist);
bool ret = circle.center.x + xscandist < 180
&& circle.center.x - xscandist > -180
&& circle.center.y + yscandist < 90
&& circle.center.y - yscandist > -90;
return ret;
}
void GeoSearch::exec() {
if(_numWanted == 0) return;
/*
* Search algorithm
* 1) use geohash prefix to find X items
* 2) compute max distance from want to an item
* 3) find optimal set of boxes that complete circle
* 4) use regular btree cursors to scan those boxes
*/
// Part 1
{
do {
long long f = found();
verify(f <= 0x7fffffff);
fillStack(maxPointsHeuristic, _numWanted - static_cast<int>(f), true);
processExtraPoints();
} while(_state != DONE && _state != DONE_NEIGHBOR &&
found() < _numWanted &&
(!_prefix.constrains() ||
_params.geoHashConverter->sizeEdge(_prefix) <= _scanDistance));
// If we couldn't scan or scanned everything, we're done
if(_state == DONE){
expandEndPoints();
return;
}
}
// Part 2
{
// Find farthest distance for completion scan
double farDist = farthest();
if(found() < _numWanted) {
// Not enough found in Phase 1
farDist = _scanDistance;
}
else if (_type == GEO_PLANE) {
// Enough found, but need to search neighbor boxes
farDist += _params.geoHashConverter->getError();
}
else if (_type == GEO_SPHERE) {
// Enough found, but need to search neighbor boxes
farDist = std::min(_scanDistance,
computeXScanDistance(_near.y,
rad2deg(farDist))
+ 2 * _params.geoHashConverter->getError());
}
verify(farDist >= 0);
// Find the box that includes all the points we need to return
_want = Box(_near.x - farDist, _near.y - farDist, farDist * 2);
// Remember the far distance for further scans
_scanDistance = farDist;
// Reset the search, our distances have probably changed
if(_state == DONE_NEIGHBOR){
_state = DOING_EXPAND;
_neighbor = -1;
}
// Do regular search in the full region
do {
fillStack(maxPointsHeuristic);
processExtraPoints();
}
while(_state != DONE);
}
expandEndPoints();
}
